National Joint Registry for England and Wales 4th Annual Report

Transcription

1 National Joint Registry ISSN National Joint Registry for England and Wales 4th Annual Report

2 Prepared by The NJR Centre, Hemel Hempstead Peter Drury Julia Morrison Claire Newell Dr Martin Pickford Martin Royall Mike Swanson Lynn May, M&M Communications Royal College of Surgeons Clinical Effectiveness Unit Jan van der Meulen Nokuthaba Sibanda The Department of Health The NJR Steering Committee This document is available in PDF format for download on the NJR website.

3 Contents Chairman s Introduction 07 Vice-Chairman s Introduction 08 Executive Summary 09 Part 1 1. Introduction Annual Report The National Joint Registry Progress Challenges Progress Key Figures Developments NJR Stakeholders, Support and Governance Information, Communication and Monitoring Finance Income and Expenditure Changes to the Levy Taking The NJR Forward Improving Data Quality and Completeness Service Development The Future NJR Steering Committee 29 Appendices Appendix 1 NJR Steering Committee 2006/07 31 Appendix 2 NJR Steering Committee Terms of Reference 34 Appendix 3 Regional Clinical Coordinators 35 Appendix 4 Regional Clinical Coordinators Network Terms of Reference 36 Appendix 5 NJR Services to Stakeholders 37 Appendix 6 NJR Units Not Returning Data in 2006/07 38 Appendix 7 Supporting Data for Figures 39 Appendix 8 Locations of Audit and Training Meetings 41 Tables Table 1 Provider: distribution of operations by type (hip or knee) and provider organisation, NJR records, 2004/05 to 2006/07 Figures Figure 1 NJR Compliance: , based on levies from implant sales Figure 2 NJR Consent: quarterly analysis of total records received and those with patient consent, 2003/ /07 Figure 3 NJR Linkability: analysis of total records received and those for which NHS numbers have been traced, 2003/ /07 Figure 4 Total: hip and knee joint replacement operations entered on the NJR, 2003/04 to 2006/07, recorded by country in which the operation took place Figure 5 Type: hip and knee joint replacement operations entered on the NJR, 2003/04 to 2006/07, recorded by type of operation Figure 6 Provider: distribution of hip and knee replacement operations by provider organisation, NJR records, for the three years 2004/05 to 2006/07 4th Annual Report 03

4 Part 2 1. Introduction Compliance and Linkage to the Hospital Episode Statistics Database Compliance for Procedures Undertaken in Linkage of NJR Procedures to HES Episodes Overview of Hip and Knee Replacement Procedures, Hospitals and Treatment Centres Participating in the NJR Hip Replacement Procedures Knee Replacement Procedures Hip Replacement Procedures Hip Replacement Procedures, Outcomes Following Primary Hip Replacement, Knee Replacement Procedures Knee Replacement Procedures, Outcomes Following Primary Knee Replacements, Prostheses Used in Hip and Knee Replacement Procedures Prostheses Used in Hip Procedures Prostheses Used in Knee Procedures Cement Use Bone Substitute Use 111 Appendices Appendix 1 Assessment Criteria for Total Hip Prostheses Utilised by the Orthopaedic Data Evaluation Panel (ODEP) 128 Tables Table 2.1 Hip or knee joint replacement procedures carried out in England between 1 April 2003 and 30 September 2006 that were linked to a HES episode, by provider type Table 2.2 Comparison of patient, procedure and provider type for HES-linked and non HES-linked hip replacement procedures, 1 April 2003 to 30 September 2006 Table 2.3 Comparison of patient, procedure and provider type for HES-linked and non HES-linked knee replacement procedures, 1 April 2003 to 30 September 2006 Table 3.1 Total number of hospitals and Treatment Centres in England and Wales able to participate in the NJR and proportion actually participating in 2006 Table 3.2 Number of participating hospitals according to number of procedures entered over the 2006 data collection period Table 3.3 Patient characteristics and procedure details according to type of provider for hip procedures in 2006 Table 3.4 Patient characteristics and procedure details according to type of provider for knee procedures in 2006 Table 4.1 Patient characteristics for primary hip replacement procedures in 2006, according to type of procedure Table 4.2 Age and gender for primary hip replacements in 2006 Table 4.3 Characteristics of surgical practice for primary hip replacement procedures in 2006, according to type of procedure Table 4.4 Thromboprophylaxis regime for primary hip replacement patients prescribed at time of operation, according to procedure Table 4.5 Reported untoward intra-operative events for primary hip replacement patients in 2006 according to procedure type Table 4.6 Patient characteristics for hip revision procedures in 2006, according to procedure type Table 4.7 Indication for surgery for hip revision procedures in 2004 to National Joint Registry

5 Table 4.8 Components removed during hip revision procedures in 2006 Table 4.9 Components used during single stage hip revision procedures in 2006 Table 4.10 Types of hip re-operation other than revisions in 2006 Table 4.11 Characteristics of patients undergoing hip re-operations other than revision Table 4.12 Revision at 1 year for primary hip replacement procedures undertaken between 1 April 2003 and 30 September 2006 that were linked to a HES episode Table 4.13 Causes of failure for primary hip replacement implants undertaken between 1 April 2003 and 30 September 2006 that were linked to a HES episode and had a revision also linked to a HES episode Table 4.14 Mortality rates and age-and-gender-standardised mortality ratios at 1 year following primary hip replacement for procedures linked to a HES `episode, Table 4.15 Mortality at 1 year for primary hip replacement procedures undertaken between 1 April 2003 and 30 June 2006 that were linked to a HES episode Table 4.16 Length of hospital stay following admission for a primary hip replacement for procedures linked to a HES episode Table 4.17 Length of hospital stay following admission for a primary hip procedure according to age and gender for procedures linked to a HES episode, Table 5.1 Patient characteristics for primary knee replacement procedures in 2006, according to type of procedure Table 5.2 Age and gender for primary knee replacements in 2006 Table 5.3 Characteristics of surgical practice for primary knee replacement procedures in 2006, according to type of procedure Table 5.4 Thromboprophylaxis regime for primary knee replacement patients prescribed at time of operation, according to procedure Table 5.5 Reported untoward intra-operative events for primary knee replacement patients in 2006 according to procedure type Table 5.6 Patient characteristics for knee revision procedures in 2006, according to procedure type Table 5.7 Combinations of implants removed during Single and 2-Stage Knee Revision procedures in 2006 Table 5.8 Types of knee re-operations entered into the NJR database Table 5.9 Characteristics of patients undergoing knee re-operations other than revision Table 5.10 Revision at 1 year for primary knee replacement procedures undertaken between 1 April 2003 and 30 September 2006 that were linked to a HES episode Table 5.11 Causes of failure for primary knee replacement implants undertaken between 1 April 2003 and 30 September 2006 that were linked to a HES episode and had a revision also linked to a HES episode Table 5.12 Mortality rates and age-and-gender-standardised mortality ratios at 1 year following primary knee replacement for procedures linked to a HES episode, Table 5.13 Mortality at 1 year for primary knee replacement procedures undertaken between 1 April 2003 and 30 June 2006 that were linked to a HES episode Table 5.14 Length of hospital stay (days) following admission for a primary knee replacement for procedures linked to a HES episode, Table 6.1 Frequency of material chosen for femoral heads in procedures performed in 2006 Table 6.2 Frequency of femoral head sizes for procedures performed in 2006 Table 6.3 Tibial insert type 2006 Table 6.4 Type of cement used in hip and knee replacement procedure cement entered into the NJR in 2006 Table 6.5 Cemented cup brands entered during 2006 for hip replacements Table 6.6 Cementless cup brands entered during 2006 for hip replacements Table 6.7 Cemented stem brands entered during 2006 for hip replacements Table 6.8 Cementless stem brands entered during 2006 for hip replacements Table 6.9 Brands of resurfacing heads entered into the NJR in 2006 Table 6.10 Procedures using a resurfacing cup with a conventional stem in 2006 Table 6.11 Top 20 Cup - Stem combinations recorded in the NJR in 2006 Table 6.12 Total Condylar knee brands entered into the NJR in 2006 for total knee replacements and hybrid and revision procedures 4th Annual Report 05

6 Table 6.13 Unicondylar knee brands entered into the NJR in 2006 for unicondylar knee procedures Table 6.14 Patello-femoral joint brands entered into the NJR in 2006 for patello-femoral joint replacement procedures Table 6.15 Fixed and rotating hinged knee brands 2006 Table 6.16 Brands of antibiotic bone cement entered into the NJR in 2006 Table 6.17 Brands of non-antibiotic bone cement entered into the NJR in 2006 Table 6.18 Brands of synthetic bone substitute entered into the NJR in 2006 Figures Figure 2.1 Flow chart illustrating linkage of the NJR with HES Figure 3.1 Number of participating hospitals by number of procedures, Figure 3.2 Primary hip procedures by provider type Figure 3.3 Primary knee procedures by provider type Figure 4.1 Type of primary hip replacement procedure undertaken between 2004 and 2006 Figure 4.2 Age and gender for primary hip replacement patients in 2006 Figure 4.3 Revision rate estimates for HES-linked primary hip replacement procedures, Figure 4.4 Revision rate estimates by age for HES-linked primary hip replacement procedures, Figure 4.5 Revision rate estimates for male and female patients with HES-linked primary hip replacement procedures Figure 4.6 Revision rate estimates for the five most commonly used hip cemented stem brands, Figure 4.7 Revision rate estimates for the three most commonly used hip cementless stem brands, Figure 4.8 Revision rate estimates for the five most commonly used hip cemented cup brands, Figure 4.9 Revision rate estimates for the three most commonly used hip cementless cup brands, Figure 4.10 Revision rate estimates for the most commonly used brand of hip resurfacing prostheses, Figure 4.11 Mortality for patients with and those without any thromboprophylaxis prescribed at the time of primary hip replacement, Figure 5.1 Revision rate estimates for HES-linked primary knee replacement procedures, Figure 5.2 Revision rate estimates by age for HES-linked primary knee replacement procedures, Figure 5.3 Survival to revision and revision rates for male and female patients with HES-linked primary knee replacement procedures, Figure 5.4 Revision rate estimates for the five most commonly used brands of total condylar knee prostheses, Figure 5.5 Revision rate estimates for the most commonly used brand of unicondylar knee prostheses, Figure 5.6 Revision rates comparing use and non-use of minimally invasive surgery in unicondylar knee procedures, Figure 5.7 Mortality for patients with and those without any thromboprophylaxis prescribed at the time of primary knee replacement, Glossary National Joint Registry

7 Chairman s Introduction Bill Darling C.B.E. D.L. F.R.Pharm.S. It is my pleasure, as Chairman of the National Joint Registry Steering Committee, to introduce our 4th Annual Report. It covers the period from April 2006 to March 2007 with a report on the analysis of data on hip and knee joint replacement operations held on the National Joint Registry in Part 2. I believe this Annual Report will prove to be of greater value to all stakeholders than its three predecessors. As the NJR data base continues to expand the quality, type and value of analysis now available from the NJR has increased significantly. We have made solid progress in a number of areas. In particular NJR Reports Online went live in October 2006 tailored to the specific needs of surgeons and hospital data managers providing access to data in the form of pre-built reports with reports for hospital management planned for the near future. During the year the NJR Information Bureau responded to a large number of requests for information, providing accessibility to data whilst at all times protecting patient and clinician confidentiality. Work on improving patient consent and compliance continues with our targets for June 2008 remaining at 90% and 95% respectively. The number of records now in the registry is close to 450,000. We have seen an increase in the level of patient consent and work is underway to help units produce forms which will allow consent to be obtained at the same time as permission to operate. The key issue of Linkability has been moved to the top of the agenda. Work is ongoing to link the NJR data to that held in the Hospital Episode Statistics (HES) and the Patient Episode Database for Wales (PEDW) which will facilitate a more detailed analysis of the data, in particular relating to revisions and outcomes. This is demonstrated in Part 2 of the Report which looks at NJR and HES linked data, increasing the ability to link revision operations to primary hip and knee joint replacement operations for patients on the NJR database. This will significantly assist survivorship analysis and will be a priority for the year 2007/08. During the year a number of hospitals began to use the NJR data for clinical audit and started to review practice in their hospital in comparison with practice nationally and in doing so seeking to improve the patient care they provide. A development which I welcome and which I hope others will adopt. Once again I record my thanks to Professor Paul Gregg who has given me great support during this year. I would also like to thank the members of the Steering Committee for their commitment and hard work to move the database forward. A key component of this progress has been the work of the Regional Clinical Coordinators who have continued to show great enthusiasm for the project. My thanks also go to the NJR Regional Coordinators; I know that their practical advice, support and guidance to orthopaedic units and other stakeholders has been much appreciated. The input of the Department of Health has been significant and in particular I would like to thank Ramila Mistry and Kate Wortham for all their help and support. Finally I record my thanks to Northgate Information Solutions whose technical expertise has enabled us to make so much progress this year and positioned us to make very real advances during Bill Darling Chairman, NJR Steering Committee 4th Annual Report 07

8 Vice-Chairman s Introduction As Vice-Chairman of the National Joint Registry Steering Committee, I am pleased to introduce Part 2 of the 4th Annual Report. Management of the National Joint Registry was awarded to a new Contractor, Northgate Information Solutions, from the 1 April Despite this significant change, we have made solid progress in a number of areas, as indicated in the Chairman s Introduction to the 4th Annual Report. Compliance and patient consent continue to improve and I am hopeful that by June 2008 our targets of 95% and 90% respectively will be achieved. A major new development has been the work to link consented NJR records to those held in Hospital Episode Statistics (HES). This should improve, dramatically, the ability to link primary procedures with subsequent revisions and, in the future, provide the opportunity of measuring other outcomes following total joint replacement surgery. Already, using this methodology, survivorship analyses for various types of total joint replacement procedures and brands of prostheses have been produced and are published, for the first time, in this Report. In particular, survivorship analysis for a significant number of hip resurfacing procedures has been performed and the results compared with more conventional hip replacement procedures. Data on unicondylar knee prostheses, mortality and its relation to thromboprophylaxis and length of stay are also presented. I believe our surgeons should be justly proud of the results which are published in this Section, particularly those relating to mortality and survivorship. I know that some believe that progress has been slower than wished for, but it is a credit to the progress that has been made, that the size of our National Joint Registry now covers almost 400 orthopaedic units, and is larger than other National Registries, for example the Swedish and Australian Registries. I wish to add my sincere thanks to those of Bill Darling, Chairman of the National Joint Registry Steering Committee, to all those who have contributed to the ongoing development of the National Joint Registry. In particular, I wish to thank Bill for all his hard work both within and outside the Committee and, of course, our surgeons for entering their data and hope that they will continue to do so. Finally, we do wish to encourage the use of NJR data for research and audit purposes. Potentially, we now have an extremely large and important database. Anyone wishing to pursue this possibility should write to the National Joint Registry Centre, following which they will be advised of the appropriate procedure. Paul Gregg Vice-Chairman, NJR Steering Committee 08 National Joint Registry

9 Executive Summary The National Joint Registry 4th Annual Report is the formal public report of the National Joint Registry for the period 1 April 2006 to 31 March In addition it contains an analysis of the data held on the Registry. The National Joint Registry (NJR) was established to improve care for patients who require hip and knee joint replacement implants and surgery. It does this by collecting data that can be used to measure the long-term effectiveness of implants used in hip and knee joint replacement surgery and information about the surgical procedures involved. The work programme of the NJR Centre in England and Wales is set and overseen by the NJR Steering Committee, working with the Department of Health as an advisory non-departmental public body. Part 1 Part 1 of this document reports on the performance and developments of the Registry during the financial year 2006/07. It provides an account of the work, composition and funding of the NJR Steering Committee and indicates key areas for future development. Key achievements and developments during the year 2006/07 included: recording 131,378 hip and knee joint replacement operations, which represented 81% 1 of such operations undertaken in NHS and independent healthcare units in England and Wales and brought the total recorded on the Registry to 433,319 by 31 March 2007 publishing a detailed analysis of data collected by the Registry increasing the number of records with patient consent to personal information being included on the Registry, from 78% in the final quarter of 2005/06 to 83% by end of 2006/07 increasing the number of records with both patient consent and the patient s NHS number, from 58% (as shown in NJR 3rd Annual Report) to 69%. Data capture has been improved by: increasing direct, on-site support for individual hospitals and treatment centres to help them set up or improve processes for submitting information introducing close monitoring of all units to identify those which may require support in improving compliance with NJR requirements gaining retrospective exemption from the Health and Social Care Act 2001, Section 60, which restricted use of the personal details of patients for whom a response of don t know had been allocated in the records patients being asked for consent to provide their personal details to the NJR at the same time as giving their consent to undergo surgery. Information held on the Registry has been made more accessible by: launching NJR ReportsOnline for surgeons and hospital data managers, which provides information about operations, case mix and implant usage improving NJR StatsOnline publishing the NJR Annual Report 2005/06 and 3rd Annual Clinical Report reporting on NJR data and services in its newsletter Joint Approach producing a starter pack of information for new unit staff. Additional developments include: devising a new, shorter, easier to use dataset for introduction in 2007/08, subject to formal approval progressing links with Hospital Episode Statistics (HES) patient records to make more data available for analysis for operations carried out on NHS patients in England holding and attending a range of events for stakeholders during 2007/08 the patient record linkage will be extended to NHS patients treated in Wales using Patient Episodes Database Wales (PEDW) a planned extension to the NJR to cover Northern Ireland. 1 Number of operations recorded on NJR relative to sales of implants between 1 April 2006 and 31 March th Annual Report 09

10 Part 2 Part 2 of the NJR 4th Annual Report summarises the data for hip and knee procedures carried out between 1 January to 31 December 2006 in England and Wales and entered into the NJR by 28 February It also includes a description of outcomes after hip and knee replacement, based on procedures entered into the NJR since the start of data collection in April 2003 that were linked to records in the Hospital Episode Statistics database. NJR compliance in 2006 The total number of levies collected between 1 January and 31 December 2006 was 154,066 and the total number of hip or knee replacement procedures reported to the NJR was 122,442 (116,046 in England and 6,396 in Wales). This suggests that the compliance rate was 79% for procedures carried out during the 2006 calendar year in the NHS and the independent sector, which is an improvement compared with 77% in 2005 and 60% in Overview of hip and knee procedures carried out in 2006 In 2006, NHS and independent sector hospitals and treatment centres (392 in England and 23 in Wales) were open and 393 (95%) submitted data to the NJR. On average, 112 hip replacements and 99 knee replacements were recorded per participating healthcare unit. The NJR recorded 61,456 hip replacement procedures, of which 10% were revisions or re-operations, and 60,986 knee replacement procedures, of which 8% were revisions or re-operations undertaken between 1 January and 31 December Of the hip procedures, 65% were carried out in NHS hospitals, 25% in independent hospitals, 5% in NHS treatment centres and 4% in independent sector treatment centres. Corresponding percentages for knee procedures were 67% in NHS hospitals, 21% in independent hospitals, 7% in NHS treatment centres and 5% in independent sector treatment centres. There was an increase in patients with mild or incapacitating disease prior to surgery in primary hip and knee replacement procedures. The percentage of patients with mild disease or more severe comorbidity increased gradually from 68% in 2004 to 76% in 2006 in patients undergoing primary hip replacement, and from 74% in 2004 to 82% in 2006 in patients undergoing primary knee replacement. 155 different brands of acetabular cups and 176 different brands of femoral stems were recorded, compared with 110 cups and 129 stems in 2005 and 88 cups and 101 stems in Of all procedures with the cup and stem brand reported in 2006, 22% used mixed and matched cup-stem combinations. The relative frequencies of the different knee procedure types have largely remained unchanged since brands of total condylar knee prostheses were recorded. In addition, there were 13 brands of unicondylar prostheses, 7 brands of patello-femoral replacement prostheses and 12 brands of hinged prostheses. The number of brands for each prosthesis type remained more or less the same compared with However, there was an increase of about 50% compared with 2004 in the number of brands used for knee replacement. Outcome of hip and knee procedures carried out between 1 April 2003 and 30 September 2006 Revision rates, mortality and length of stay were analysed using data obtained from linkage of the NJR to the Hospital Episode Statistics (HES) database, with special attention given to hip resurfacing and unicondylar knee replacement. The HES database records procedures undertaken in England and includes only patients treated in NHS hospitals, in NHS treatment centres, and those treated in independent hospitals and independent sector treatment centres with NHS funding. When interpreting the revision rates, one should take into account that not all revision procedures that occurred may have been identified through the linkage process. Furthermore, when comparing revision rates with other national registries, one should take into account that there may be differences in the definition of a revision and that re-operations may have been included by some registries. Of all 355,480 hip or knee replacement procedures recorded in HES and carried out between April 2003 and September 2006 at NHS hospitals and NHS treatment centres, or in the independent sector and funded by the NHS, 187,220 (53%) could be linked to the NJR. Linkage was not possible for procedures that were not recorded in the NJR (non-compliance) or for those recorded procedures for which patient identifiers were not available. There has been a trend towards more cementless total hip replacement procedures and fewer cemented procedures since Cementless hip replacements increased gradually from 21% in 2004 to 30% in 2006 and cemented replacements declined from 53% in 2004 to 48% in These are the figures for the calendar year, 1 January 2006 to 31 December 2006 and will vary from figures quoted for the financial year 1 April 2006 to 31 March 2007 elsewhere in the Report 10 National Joint Registry

11 The number of procedures that could be linked differed between provider types. About 70% of hip or knee replacement procedures undertaken at NHS hospitals or NHS treatment centres could be linked, compared with only about a quarter of those carried out at independent sector treatment centres, and less than 10% of those carried out in independent hospitals. Therefore, the HES-linked procedures are most representative of procedures undertaken at NHS hospitals and NHS treatment centres in England. The overall revision rate for primary hip replacement was 0.7% (95% CI 3 : 0.6% to 0.7%) at 1 year and 1.3% (95% CI: 1.2% to 1.5%) at 3 years. Procedure type was found to be the most influential factor on implant survival following primary hip replacement. 1 year revision rates after hip resurfacing (1.6%, 95% CI: 1.3% to 2.0%) were five times higher than cemented total hip replacement (0.3%, 95% CI: 0.3% to 0.4%). After adjusting for patient age, gender, general medical condition and provider type, hip resurfacing procedures were found to still have a statistically significantly higher revision rate (hazard ratio 4.6, 95% CI 3.4 to 6.2) within 1 year compared with cemented total hip replacement. There was evidence that a large number of the failures of hip resurfacing prostheses were in older female patients, indicating the need for careful patient choice. Analysis of longer term survival is necessary to establish the comparative long term performance of hip resurfacing. The average length of hospital stay after a primary hip replacement was 9.1 days. The shortest length of hospital stay was found in patients undergoing hip resurfacing, with an average stay of 6.3 days. Following primary knee replacement, patients stayed on average 8.1 days in hospital. After unicondylar knee replacement, length of stay was only 5.9 days. In this Report it was possible to present analyses of short-term outcomes only up to 3 years following primary hip or knee replacement on account of length of follow-up that the NJR allows at the present time. Analysis of longer term outcomes are necessary to establish whether the results seen persist. Furthermore, the analyses were based on data obtained from the linkage of NJR with HES, an exercise that was undertaken for the first time in this Report and in which linkage was not possible for all recorded procedures. The results presented should be interpreted with these factors in mind. The overall revision rate for primary knee replacement was 0.4% (95% CI 0.3% to 0.4%) at 1 year and 1.4% (95% CI: 1.2% to 1.6%) at 3 years. Revision rates at 1 year were similar between cemented total knee and unicondylar knee primary replacements. 0.3% of cemented knee replacements needed revision within 1 year, compared with 0.4% of unicondylar knee replacements. Mortality at 1 year was 1.9% after hip replacement and 1.6% after knee replacement, which is less than half of that observed in the age-matched and sex-matched general population in England and Wales. These differences demonstrate that patients who undergo hip or knee joint replacement are a highly select group. A thromboprophylaxis regime was prescribed for 74,868 (98%) of primary hip replacement patients and 76,581 (98%) of primary knee replacement patients. There was no difference in mortality up to 1 year following primary hip or knee replacement between patients for whom thromboprophylaxis was prescribed and patients for whom none was prescribed. 3 CI: Confidence Interval (Statistical Term) 4th Annual Report 11

12 Part 1 1. Introduction 12 National Joint Registry

13 1.1 Annual Report This is the fourth annual report of the National Joint Registry (NJR), which provides information about hip and knee replacement operations in England and Wales within both the NHS and independent healthcare sector. This information is valuable to surgeons, patients, members of the public and the manufacturers of hip and knee implants (artificial joints). NJR collects information that can be used to help improve care and treatment through information on surgical practice and on the hip and knee implants used in joint replacement surgery. The Report has been divided into two sections for ease of reference - a general outline of the work on the NJR and an analysis of the operations recorded by the Registry. Part 1 a review of progress made on the NJR during the financial year 1 April 2006 to 31 March 2007 and its plans to increase still further the value of its information in the future. Part 2 an analysis of the data recorded in the calendar year 1 January and 31 December 2006 and, using information recorded on NJR since April 2003, it focuses on: linked primary and revision operations; hip resurfacing; unicondylar knee replacement and mortality rates. The quality of the information received is very important to the NJR as it affects the level of detail the NJR is able to give to those who are interested in its findings (a list of stakeholders can be found in Section 2.5). To support the collection and use of data, it is important that data collection and entry into NJR is made as easy as possible and that information held on NJR is available when required (see Section 2.4 for developments in these areas) Management and funding The NJR has been managed by Northgate Information Solutions (UK) Ltd since April 2006, under a contract with the Department of Health, and is funded through a levy raised on the sale of hip and knee replacement implants (further information regarding funding is available in Section 5 Part 2). The NJR s Steering Committee (NJRSC), which was set up in October 2002, is an advisory non-departmental public body. A list of NJRSC members and members declarations of interest is contained in Appendix 1 with the Terms of Reference detailed in Appendix 2. Further information about the NJRSC s work during 2006/07 is featured in Section The National Joint Registry The NJR was set up in October 2002 and began collecting data on hip and knee replacement operations in April The NJR was set up to improve patient care by finding out more about hip and knee joint replacement implants and surgery. It is doing this by building up a database of information. The aim is for the Registry to be able to provide information for patients, surgeons, hospitals, manufacturers and healthcare regulatory agencies on implant performance, joint replacement surgery and best surgical practice. The NJR can only achieve its aims if it has a timely and continuous supply of high quality information about the operations that are carried out. This information makes it possible to monitor the performance and long-term effectiveness of hip and knee replacement surgery and the implants, known as prostheses, used. The information on NJR is made available to surgeons, patients, the public and the manufacturers of replacement joints to help improve care and treatment in the future. Data is provided to the NJR by NHS and independent healthcare providers throughout England and Wales. By 31 March 2007 it had received 433,319 records. 4th Annual Report 13

14 Part 1 2. Progress 14 National Joint Registry

15 2.1 Challenges The success of the NJR is reliant on meeting three main challenges: improving the completeness and quality of the information held on the Registry; reducing the burden of data entry on hospitals and units supplying the information and making information held on NJR available for better patient care. The continuing challenges on data completeness and quality are to ensure: all hip and knee joint replacement operations carried out in England and Wales are recorded on the NJR the recorded information is of good quality patient consent is given for data to be stored and used to achieve the aims of the NJR. Over the last four years the level at which these data challenges have been met has increased significantly (see point 2.2). During 2006/07 the NJR Centre improved the way in which on-site support to individual NHS and independent healthcare hospitals and treatment centres (known as units) is managed and prioritised. (Examples of these improvements are detailed at Section 2.5 under the heading, Regional Coordinators). There are three ways of measuring these areas of data quality and completeness: compliance the percentage of records submitted to the NJR compared with the total number of hip and knee replacement operations carried out in England and Wales, also referred to as case ascertainment target 95% by June 2008 consent the percentage of records submitted to the NJR with consent given by patients for use of their personal information 4 target 90% by June 2008 linkability the percentage of records that have patient consent and the patient s NHS number so that all operations performed on the same patient can be linked. The goals of the NJR will only be achieved if operations on the same patient can be successfully linked target 90% by June In addition to addressing these targets, the NJR Centre s work during 2006/07 centred on: making it easier for records to be submitted sharing best practice through workshops for staff involved in the administration of NJR in NHS and independent healthcare units and encouraging them to share ideas. Regional Coordinators have also been active in sharing information about the most effective processes during their visits to units where submission of data to NJR is poor making information more easily accessible to surgeons, staff in units using the NJR and hospital management. NJR ReportsOnline has been implemented, giving local, summary information about the NJR, for example, case mix and implant usage for surgeons. Reports have been designed for hospital managers and will be implemented in 2007/08 improving performance monitoring. These initiatives, which are designed to help ensure that the commitment of stakeholders to NJR is maintained, will be progressed further during the year ahead. More work will be undertaken to improve still further the information available to stakeholders, for example, through the links being developed with other NHS systems. 2.2 Progress Progress on these challenges during 2006/07 is considered across the different areas Data completeness and quality compliance All NHS and independent healthcare units in England and Wales are asked to submit details of their hip and knee replacement operations. The method used to monitor compliance with this request is to compare the number of levies raised from the sale of implants to the number of submissions from units. Figure 1(overleaf) illustrates the compliance rate (case ascertainment) across all units over the last four years. Compliance increased significantly over the first three years of the NJR. In 2003/04, from 156,354 operations 5 which took place, 62,191 operations were recorded on the NJR giving a compliance rate of approximately 40%, but by 2005/06, the rate had risen to 82%, 132,578 of 161,000 operations. The rate decreased slightly during 2006/07 to 81.3%, 131,378 of just under 158,000 operations against an apparent decrease in the number of operations performed in England and Wales based on the levies collected from implants sold. Of the units expected to submit data to the NJR 11 failed to submit any records during 2006/07. These are listed in Appendix 6. 4 Personal information includes NHS number, surname, date of birth and postcode 5 Operations this is an estimate of the number of hip and knee joint replacement operations performed in England and Wales based on the number of levies collected on implants sold 6 This is for the financial year from 1 April 2006 to 31 March th Annual Report 15

16 NJR Records 180, , , , ,000 80,000 60,000 90% 80% 70% 60% 50% 40% 30% Consent Rate (%) Figure 1 NJR Compliance: , based on levies from implant sales Source: Operations entered on NJR 1 April March 2007 and levy submissions to NJR by implant suppliers and manufacturers. For supporting data see Appendix 7 40,000 20, / /05 Year 2005/ /07 20% 10% 0 % Number of NJR Operations Levy Compliance Consent Why is it important for patients to give consent? By consenting to the inclusion of their personal details on the NJR database, patients enable more accurate study of the outcomes of hip and knee replacement operations. In turn, this means the NJR is able to provide information that can be used to: improve awareness of the outcomes of replacement surgery help patients obtain the best clinical care for joint replacement surgery look at the performance of implants and help identify any brand of implant showing high failure rates improve surgical practice including information that can be used to identify best surgical practice help NHS and other healthcare organisations to make best use of their resources. Patients must give consent for their personal details to be used on the NJR database and once they understand the purpose of the NJR, they rarely refuse to give consent when asked. Recording a patient s personal details, including their NHS number, enables the linking of operations for that patient that have either been carried out already or may be carried out in the future. This will enable problems either with implants or surgical techniques to be identified at an early stage and the appropriate action taken. This information on NJR will also enable hospitals to be identified and assisted when they need to recall patients who have received an implant that is suspected of failing to perform as expected. The rates of patient consent are published monthly on the NJR website in NJR StatsOnline ( The percentage of records submitted to the NJR with the necessary consent rose from 78% (29,238 of 37,416 NJR records) in 2005/06 Quarter 4 (1 January to 31 March 2006), to 83% (30,746 of 36,862 NJR records) in 2006/07 Quarter 4 (1 January to 31 March 2007). Figure 2 (right) shows the pattern of patient consent over the last four years. A consent rate of approximately 64%, 39,433 from 61,781 recorded operations was reported in the NJR s first year; this dipped to below 60%,16,273 of 27,249 recorded operations during the second quarter of 2004/05 but it has risen virtually every quarter since then. Further improvement is needed in order to achieve the target of 90% by June At present, when submitting records, participating units may choose from three options for patient consent: yes, no and don t know. During 2006/07, of 131,378 records submitted to the NJR, 6% (7,680) included a no response and 13% (16,551) don t know. It is likely that many of the don t know and no responses arise because either the patient has not been asked for consent or the completed consent form was not available at the time of entering the record. 16 National Joint Registry

17 Figure 2 Number of operations on NJR and number with consent 40,000 35,000 30,000 25,000 20,000 15,000 10,000 90% 80% 70% 60% 50% 40% 30% 20% Consent Rate (%) NJR Consent: quarterly analysis of total records received and those with patient consent, 2003/ /07 Source: Operations entered on NJR 1 April March For supporting data see Appendix 7 5,000 10% Number of Operations 0 0 % Number of Consent Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 2003/ / / /07 Consent Rate Section 60 exemption During the year in view, the NJR Centre was granted exemption 7 by the Patient Information Advisory Group (PIAG) from some of the requirements of the Health and Social Care Act 2001, Section 60. This means that for all the records submitted to NJR with a don t know response regarding consent, a patient s personal details may be recorded for the purposes of improving linkability of NJR records with other records on the same patient. However, if a patient later refuses consent, their personal details will be removed from the NJR records. The data entry system was altered on 31 March 2007 to support this change. The exemption is retrospective, enabling the NJR Centre to begin to improve the linkability of previous years records Changes to the consent process The NJR Centre has been looking at ways to help units with the patient consent process. During 2006/07 it was confirmed that NJR consent can be sought at the same time as consent to operate, providing it is made clear to patients that receiving treatment is not dependent on giving consent for their data to be stored on the NJR. This removes the problems associated with having to seek consent from patients for their personal details to be placed on the NJR at a different time from their consent to operate. Work has started on local consent to operate forms to enable units to have approved text which they can add to their own, local consent to operate forms Linkability Linkability enables comparisons to be drawn between operations, for example, by looking at the primary (first) hip or knee joint replacement operation and the subsequent revisions or re-operations on the same joint in the same patient. The accuracy of findings from the NJR depends on having a sufficiently high number of NJR records containing patient information that will allow the NJR record to be linked to another record of the same patient. In order for records to be linked, patient consent is required for the storage of personal information. Records must include either the patient s NHS number or their surname, date of birth and postcode, so that the NHS number can be traced through the National Strategic Tracing Service (NSTS). The percentage of linkable records held on the NJR from 2003/04 to 2006/07 is shown in Figure 3. The level has improved significantly from 45% (27,807) of the 61,781 records submitted in 2003/04 to 60% (79,733) of 132,191 records two years later in 2005/06 and 69% (90,502) of 130,927 records submitted in 2006/07. Further work will be needed to reach the target of 90% by June Plans include use of mandatory information on the data collection form and using other NHS databases (HES and PEDW) to help find the NHS number. 7 This is an annual exemption and has to be re-applied for each year 4th Annual Report 17

18 140,000 80% Figure 3 Number of records submitted and with NHS number after NSTS search 120, ,000 80,000 60,000 40,000 20,000 70% 60% 50% 40% 30% 20% 10% NJR Linkability: analysis of total records received and those for which NHS numbers have been traced, 2003/ /07 Source: Operations entered on NJR 1 April March For supporting data see Appendix / /05 Year 2005/ /07 0 % Number of Operations Number with NHS Number LinkageRate 2.3 Key Figures On the record NJR records include the following information about each operation: patient details (if patient consent is recorded) hospital surgeon operation surgical approach any untoward event which may have occurred during the operation Operation totals Since the launch of the NJR in April 2003, a total of 433,319 hip and knee joint replacement operations in England and Wales has been recorded on the NJR. During the first year, 2003/04, the number of operations reported was 62,189; with this rising to 107,172 in 2004/05 and 132,577 in 2005/06. However, in 2006/07, the figure for the year dropped slightly, to 131,378, which is 1,199 (0.9%) fewer than the previous year. This represents a minor decrease in compliance (fewer operations recorded on NJR). See Appendix 7 for supporting data. Figure 4 (right) shows the total number of operations recorded on NJR in England and Wales each year from 2003/04 to 2006/07. It shows that the figures for Wales have increased each year and that, in 2006/07, for the first time, the number of knee joint replacement operations was greater than the number of hip joint replacement operations in both countries. In England, during 2006/07, 61,940 knee operations and 61,849 hip operations were recorded on the NJR; whilst in Wales, the figures were 3,683 for hip operations and 3,906 for knee operations. 18 National Joint Registry

19 Number of Operations 70,000 60,000 50,000 40,000 30,000 20,000 Figure 4 Total: hip and knee joint replacement operations entered on the NJR, 2003/04 to 2006/07, recorded by country in which the operation took place Source: Operations entered on NJR 1 April March ,000 0 England Hip Wales Hip 2003/04 32, /05 53,513 1, /06 63,595 2, /07 61,849 3,683 England Hip Wales Hip England Knee 28,450 50,606 62,959 61,940 England Knee Wales Knee 692 1,448 3,033 3,906 Wales Knee Operations by year and country Total operations: 2003/04 62, /05 107, /06 132, /07 131, Operation types Hip and knee joint replacement operations take three forms: primary the first time a joint is replaced revision an operation that involves the removal and replacement of one or more components of a joint replacement The greatest number of operations is of the primary kind. In 2006/07, for example, 121,102 (92%) of the 131,378 operations recorded were primary operations; only 9,592 (7%) were revisions and 684 (0.5%) re-operations. During the NJR s first two years, the number of primary hip joint replacement operations that were recorded outnumbered the number of primary knee joint replacement operations recorded; however, that trend was reversed in both 2005/06 and 2006/07. In 2005/06 primary knee joint replacement operations exceeded primary joint replacement hip operations by more than 2,500 (4.4%) and last year, this figure rose to more than 3,000 (5.4%). Figure 5 (overleaf) shows the number of operations by type from 2003/04 to 2006/07. (Note, hip and knee joint replacement re-operations where not collected in 2003/04). re-operation other than revision - an operation following either a primary or revision operation that does not require any joint implants to be removed or replaced, for example, if an implant needs to be re-aligned or has become loose. 4th Annual Report 19

20 Number of Operations 70,000 60,000 50,000 40,000 30,000 20,000 Figure 5 Type: hip and knee joint replacement operations entered on the NJR, 2003/04 to 2006/07, recorded by type of operation Source: Operations entered on NJR 1 April March , / / / /07 Hip Primary Hip Primary Knee Primary Revision Hip Revision Knee Hip Re-operation Knee Re-operation 30,036 27,911 3,012 1,232 n/a n/a 49,687 49,567 5,186 2, ,000 62,616 6,237 3, ,952 62,150 6,272 3, Knee Primary Revision Hip Revision Knee Hip Re-operation Knee Re-operation Operations by year and joint/type Total operations: 2003/04 Hip: 33,048 Knee: 29, /05 Hip: 55,118 Knee: 52, /06 Hip: 66,585 Knee: 65, /07 Hip: 65,532 Knee: 65, Where did the operations take place? In total, of the 433,319 operations recorded over the last four years, 415,133 (96%) were carried out in England and 18,183 (4%) in Wales. During 2006/07, England carried out 123,789 (94%) and Wales 7,589 (6%), as shown in Figure 4 (above). Patients in England may have their hip and knee joint replacement operations with one of four different types of organisation: NHS hospital NHS Treatment Centre Independent healthcare hospital Independent Treatment Centre There are no NHS or independent treatment centres in Wales. To date, most of the 433,319 operations recorded on NJR were carried out in an NHS hospital: 264,578 (61% of all operations) in England and 13,905 (3% of all operations) in Wales. Independent healthcare hospitals have undertaken 119,590 (28%) of the recorded operations in England and 4,278 (1%) in Wales. The number of hip and knee joint replacement operations 20 National Joint Registry

21 carried out at treatment centres in England has continued to increase. NHS treatment centres have carried out 18,287 (4%) of the operations over the last four years, whilst independent healthcare treatment centres have carried out 12,681 (3%). For supporting data see Appendix 7. The number of operations carried out in treatment centres has risen steadily over the last three years (see Table 1, overleaf). Of the 107,172 recorded operations in 2004/05, 3,202 (3%) were at NHS treatment centres and 1,852 (2%) at independent treatment centres, while of the 131,378 recorded in 2006/07, 7,572 (6%) were at NHS treatment centres and 6,383 (5%) at independent treatment centres. During the same period (see Figure 6 below), the proportion of hip and knee joint replacement operations recorded on NJR in NHS hospitals remained relatively unchanged (69,300 (64%) in 2004/05 and 86,979 (66%) in 2006/07) but the proportion in independent hospitals dropped, from 32,818 (31%) in 2004/05 and 39,635 (30%) in 2005/06 to 30,444 (23%) in 2006/07. The proportion of hip joint replacement operations recorded at NHS hospitals during this period was much the same at 39,474 (33%), while knee joint replacements rose slightly from 32,199 (32%) to 41,117 (34%). The corresponding decrease in operations at independent hospitals shows a drop from 17,703 (17%) hip and 15,115 (14%) knee in 2004/05 to 16,499 (13%) hip and 13,945 (11%) knee joint replacement operations in 2006/07. Further analysis of the types of organisation in which patients have hip and knee joint replacement operations is provided in Figure 6 (below) and Table 1 (overleaf). Figure 6 Provider: distribution of hip and knee replacement operations by provider organisation, NJR records, for the three years 2004/05 to 2006/ / /07 Independent Treatment Centres 4,114 3% Independent Hospitals 39,635 30% Independent Treatment Centres 6,383 5% NHS Hospitals 81,534 61% NHS Treatment Centres 7,294 6% NHS Treatment Centres 7,572 6% 2004/05 Independent Treatment Centres 1,852 2% NHS Treatment Centres 3,202 3% Independent Hospitals 30,444 23% NHS Hospitals 86,979 66% Independent Hospitals 32,818 31% NHS Hospitals 69,300 65% Source: Operations entered on NJR 1 April March For supporting data see Appendix 7. 4th Annual Report 21

22 Table 1 Provider: distribution of operations by type (hip or knee) and provider organisation, NJR records, 2004/05 to 2006/07 Number of Operations 2004/ / /07 NHS Hospital Independent Hospital NHS Treatment Centre Independent Treatment Centre Total Hip 35,040 17,703 1, ,118 Knee 34,260 15,115 1,654 1,025 52,054 Total 69,300 32,818 3,202 1, ,172 Hip 40,600 20,647 3,403 1,935 66,585 Knee 40,934 18,988 3,891 2,179 65,992 Total 81,534 39,635 7,294 4, ,577 Hip 42,658 16,499 3,425 2,950 65,532 Knee 44,321 13,945 4,147 3,433 65,846 Total 86,979 30,444 7,572 6, ,378 Source: Operations entered on NJR 1 April March Developments Reducing workload for stakeholders Data entry can be a burden on stretched resources, which is why the NJR Centre has developed a number of measures to reduce the effort involved in capturing and inputting data. These measures should help to increase compliance rates further and improve data quality Reviewing the information requested The NJR received the records of a high proportion of the total number of hip and knee joint replacement operations in England and Wales. However, the amount of detail in the records submitted to NJR was variable. Units provide information to the NJR using a special on-line form. During 2006/07 the NJR Centre reviewed responses to the dataset and found that, unless a question was mandatory, the requested information was not provided in many instances. Following the review the NJR Centre was keen to improve the dataset in order to: obtain all the information vital to the achievement of NJR goals make it simpler for the units to use. The result is a proposed new, shorter dataset (MDSv3) in which all questions are mandatory. This proposed dataset has been approved by the NJR Steering Committee and, during 2007/08, will be submitted to the Review of Central Returns (ROCR) 8 for the approval required before it can be put into practice Bulk upload To help reduce the burden of entering information into different databases, it is possible for units to collect NJR data through their own computer system and transfer it as a block of multiple data records, at regular intervals, to the NJR database. This bulk upload facility saves time spent manually inputting data to the NJR and helps to preserve data quality. In total 1,014 records were uploaded through bulk upload during 2005/06 and 2,555 records in 2006/07. Improvements will be made in the short term to ensure that it can transfer component data with longer term solutions to be explored Components database The number of different implant component parts recorded on the NJR exceeds 50,000 and continues to grow. NJR needs up to date information on all implants used in England and Wales so that units can record the implant used accurately on the Registry. Implant suppliers are required to enter details of all new components onto the NJR before any are sold, but this is not happening routinely. In addition, a system of barcode scanning enables hospital staff automatically to enter implant details onto the NJR, which saves them time and helps to preserve data quality. Some suppliers have made changes to barcode formats without informing the NJR, which has reduced the number of implants with information that can be scanned into NJR. The NJR Centre has been working closely with suppliers to overcome these problems and will continue to do so in 2007/08. 8 ROCR is charged with minimising the burden of all ongoing and one-off central information requirements on the NHS. Only data collections that have been approved by ROCR are added to the list of authorised central returns published on the Internet 22 National Joint Registry

23 2.5 NJR Stakeholders, Support, and Governance This section outlines the numerous stakeholders who have an interest in the outcomes of the work undertaken by the NJR. It also describes the organisations and individuals who guide the work of the NJR, champion the NJR to hospital managers and clinicians, and who work with hospitals to ensure that good quality information is submitted to the NJR Stakeholders The information held on NJR is of interest to numerous individuals and organisations and the NJR Centre is committed to working with these stakeholders in order to provide them with a valuable information service tailored to their individual needs NJR stakeholders Patients and patient groups Orthopaedic surgeons and professional bodies, including the British Orthopaedic Association, British Hip Society, British Association of Surgery of the Knee and Royal College of Surgeons Hospital staff, including theatre nurses, data entry staff and hospital management Other healthcare professionals practitioners with a special interest in orthopaedics, including nurses, physiotherapists, occupational therapists, GPs and arthroplasty practitioners Industry orthopaedic implant suppliers and manufacturers and the Association of British Healthcare Industries NHS management and commissioners NHS trusts, NHS foundation trusts, primary care trusts, strategic health authorities, Welsh NHS regions, GPs and practice-based commissioners Public health specialists, epidemiologists and other researchers Independent healthcare management the Independent Healthcare Advisory Service, independent hospitals and independent treatment centres NHS Supply Chain Regulatory bodies, including the Medicines and Healthcare Regulatory Agency, Healthcare Commission, National Patient Safety Agency and National Institute for Health and Clinical Excellence Government Ministers, Department of Health and Welsh Assembly Other stakeholders such as the Scottish Executive NJR Steering Committee members Priorities During 2006/07 the NJR Centre s work focused on its targets for compliance, consent and linkability. Stakeholders with whom the NJR Centre worked most closely on this initiative were orthopaedic surgeons, management and staff responsible for the NJR process and those routinely requiring information from NJR The NJR Centre is committed to continuing this level of engagement which: supports and encourages units to submit good quality data ensures that it fully understands the information requirements of these stakeholders and delivers on them wherever possible helps key stakeholders to access and use NJR information to improve patient care. In addition, the NJR Centre will be working with a wider range of stakeholders during 2007/ Regional Coordinators The NJR Centre has six Regional Coordinators (RCs), each providing direct, on-site support to approximately 70 units. The RCs provide a critical link between NJR users and the NJR Centre. Their two-way communications role involves feeding back information about stakeholder requirements and issues while passing on to the units information about NJR developments RC duties include: helping units to set up or improve processes for submitting information providing training to unit staff to ensure they can access information helping units to make best use of NJR information by publicising all new aspects of the system including NJR StatsOnline and NJR ReportsOnline and encouraging them to use the Information Bureau provided by the NJR Centre sharing best practice among units monitoring unit performance helping units to improve their performance where this is as a result of poor compliance and consent rates. On-site support by the RCs to individual NHS and independent healthcare hospitals and treatment centres has been improved in the year in question. RCs now have access during site visits to up to date information about the progress of hospitals and treatment centres in terms of the NJR s own performance indicators and are able to identify trends. 4th Annual Report 23

24 2.5.7 Regional Clinical Coordinators In addition to Regional Coordinators there are NJR Regional Clinical Coordinators (RCCs), who are consultant orthopaedic surgeons. These are honorary posts with the primary role to act as NJR local champions, working with colleagues and teams in units within their area to ensure that the purpose and benefits of the NJR are understood and to encourage compliance with NJR data requirements. The RCCs are provided with regular reports about the overall performance of units in their area. They work closely with RCs, providing advice and support that will enable them to assist individual units to improve performance. The RCC Network advises the NJR Centre on orthopaedic matters and met four times during 2006/07. All members were involved in the review of the NJR dataset (see Section 2.4). The RCC Network Chair is an RCC who is appointed to the post following interview by the Department of Health. The RCC Network Chair has an observer seat on the NJR Steering Committee. During the year in view, a change in the RCC Network was necessary in order to tie in with England s new SHA (Strategic Health Authority) structure. There are now two RCCs per SHA and one per Welsh NHS region. New terms of reference were drafted for RCCs (see Appendix 4). Following a review it was decided to absorb the work of the NJR Outlier Performance Advisory Group (NOPAG), Editorial Board, Patient Reported Outcomes Measurement Study and Research Sub-Committees into the work of the Steering Committee. This ensured that all NJR Steering Committee members had an opportunity to contribute to the full range of work. Firmer links were forged with the RCC Network through the assignment of the three surgeon members of the NJRSC to support their RCC colleagues. An observer seat has been provided on the NJRSC for the RCC Network Chair and minutes between the RCC Network and the NJR Steering Committee continued to be exchanged. 2.6 Information, Communication and Monitoring Keeping stakeholders informed The need to provide timely and accurate information to stakeholders is a priority and the NJR Centre is making information available in a variety of ways. During 2006/07 it introduced a performance management system to help manage the information submitted to, and held, on NJR. This enabled the NJR Centre to make the improvements outlined below NJR Steering Committee The programme of work for the NJR is set and monitored by the NJR Steering Committee (NJRSC) in conjunction with the Department of Health. The NJRSC met four times during 2006/07. The minutes of the meetings are posted on the NJR website ( steeringcomm/sc_index.htm). In October 2006, the NJR Steering Committee adopted its new constitution in line with its re-designation from departmental committee to advisory non-departmental public body. The term of office for all but one member of the Steering Committee expired in 2006/07, with the last one ending on 30 April The Committee s current members were appointed by the Appointments Commission during 2006/07 on behalf of the Secretary of State for Health following a formal recruitment process (for a list of full members and observers see Appendix 1 and NJR website ex.htm). Recruitment was targeted towards Northern Ireland, as well as England and Wales, reflecting the intention to extend the geographical area of the NJR to include Northern Ireland. A patient representative member was appointed from Northern Ireland and one from Wales. An induction day was provided for Steering Committee members on 21 September NJR ReportsOnline Information about operations, case mix and implant usage can now be found in a range of reports for surgeons and hospital data managers. These are published in NJR ReportsOnline, which went live in October 2006 and enables surgeons not only to look at all the operations they have performed but also to study the different types of operation (case mix) and the profile (e.g. age and sex) of the patients undergoing the surgery. They may also look at the type and number of implants they have used for those procedures. They may see this information for each of the hospitals with which they are registered. Access is controlled so that only a surgeon can see surgeon reports and only surgeons can see information about the operations that they themselves have undertaken. In addition, the reports are anonymised so that patients cannot be identified from the information provided. Surgeons are, however, entitled to see any NJR data relating to a patient in their care Performance monitoring New management reports closely monitor all aspects of the performance of units in terms of their entry of data on NJR (compliance) and patient consent, helping to focus on the support required from the NJR Centre for individual units. 24 National Joint Registry

25 2.6.3 NJR StatsOnline NJR StatsOnline is accessible to all through the NJR website ( and provides information, updated monthly, on all independent healthcare and NHS hospitals and treatment centres in England and Wales that carry out hip and knee joint replacements. This information includes the total number of operations submitted to the NJR, the number of hip and knee joint replacement procedures and the percentage of records that have NJR patient consent. The format of NJR StatsOnline was changed during 2006/07 to reflect England s new SHA (Strategic Health Authority) structure and to provide information based on operation date as well as submission date. During the year ahead, NJR StatsOnline will be enhanced with further information to enable more effective comparisons to be made between operations. In addition, information will be provided to enable comparisons to be made at national, SHA, NHS trust and unit (hospital and treatment centre) levels Information Bureau The NJR Centre provides an Information Bureau, which supplies tabulations or extracts of NJR data and other NJR information in response to specific requests. All information is released with due regard to patient and clinician confidentiality and, in the case of implant information, to commercially sensitive information. An NJR Information Sharing and Governance Protocol, outlining the operations and guidelines for the release of information 9, is due to be published on the NJR website during Communications Communication with NJR stakeholders during the year in view involved: increased direct support for units contributing low levels of data or data with unacceptably low rates of patient consent holding the initial regional workshop and presenting at orthopaedic audit and training meetings to inform stakeholders of planned service developments and to encourage participation in the NJR NJR Centre staff attending audit and training meetings in a number of hospitals, see Appendix 8 publicising planned developments for the service through attendance at conferences including the British Orthopaedic Association, British Hip Society and British Association for Surgery of the Knee in addition to the Nuffield Hospitals Conference and Training Seminar Publications Several publications were produced during 2006/07, reporting on NJR data or services. These publications, which may be found on the NJR website, included: National Joint Registry Annual Report 2005/06 National Joint Registry 3rd Annual Clinical Report one issue of the NJR Newsletter, Joint Approach a starter pack of information about the NJR, guidelines and user manuals for new unit staff HES links During 2006/07 the NJR Centre made progress on a method of linking with HES patient records that date back to This work is important as it will: make available more data that can be used for analysis of NJR data improve outcomes based analysis for stakeholders Communications strategy The NJR Centre has started work on a communications strategy to assess the most effective ways of communicating with stakeholders, including orthopaedic surgeons, senior NHS and independent healthcare managers, unit staff, suppliers, regulatory agencies and patients. New patient information posters for out-patient departments and pre-operative assessment sessions are planned for enable more accurate monitoring of compliance with NJR data requirements. A similar link is planned be implemented between the NJR and PEDW. 9 The Department of Health (DH) is the Data Controller, Northgate Information Solutions Ltd is the Data Processor on behalf of the DH as the holder of the contract for the management of the NJR 4th Annual Report 25

26 Part 1 3. Finance 26 National Joint Registry

27 3.1 Income and Expenditure The NJR is self-financing, funded by a levy raised on the sale of hip and knee implants to NHS and independent healthcare providers in England and Wales. The rate of the levy is set by the Health Minister and is subject to a Memorandum of Understanding between the Department of Health, the National Assembly for Wales, the Independent Healthcare Forum and the Association of British Healthcare Industries Orthopaedic Special Interest Section. Income to the NJR for 2006/07 was 2,618, and expenditure for the same period was 2,057, Members of the NJRSC and the RCC Network are volunteers and do not receive payment for their work. However, they are reimbursed for any travel and subsistence expense incurred while attending meetings. The total expenditure for members expenses during 2006/07 was 18, Changes to the Levy The levy was reduced from 25 to 23 on 1 June 2006 and, following a review by the NJRSC and the Health Minister, it will be further reduced to 20 from 1 June th Annual Report 27

28 Part 1 4. Taking the NJR Forward 28 National Joint Registry

29 4.1 Improving Data Quality and Completeness To deliver the NJR aims it is essential that the data held on the Registry is complete and of good quality. As detailed earlier in this document, the targets set involve reaching the following levels by June 2008: 95% compliance (case ascertainment) the proportion of all hip and knee joint replacement operations for which records are submitted to the NJR 90% consent the proportion of records submitted to the NJR which include patient consent to store personal details 90% linkability the proportion of records submitted to NJR with information which would allow them to be linked to other records on the same patient for analysis purposes. 4.2 Service Development Reference has been made in this Report to a number of developments, which are summarised here. Subject to approval, implementation of a new dataset (MDSv3), which will reduce the amount of data required from units and improve NJR data. 4.3 The Future The intention is to extend the geographical area covered by the NJR to include Northern Ireland. The NJR Centre will monitor the development and progress of NJR in relation to other national hip and knee joint replacement registries and take action as appropriate in discussion with the NJRSC and Department of Health. Regional Clinical Coordinators will continue to be the local champions of the NJR, working closely with NJR Regional Coordinators. 4.4 NJR Steering Committee The Committee membership under the new constitution was completed by 1 May 2007, allowing new and existing members to work together to fulfil NJRSC s role as an advisory non-departmental public body. It will continue to work with the Department of Health to set the work programme for, and oversee the activities of, the NJR, advising Health Ministers, hospitals and suppliers as required. Linking NJR data to HES and PEDW data to provide more information for analysis. Continuing to improve the data and information made available through NJR StatsOnline and NJR ReportsOnline. Developing communications and working relationships with orthopaedic surgeons, healthcare management, patients and other stakeholders. Looking at ways to improve integration of the NJR with other databases to reduce the need to enter the same data several times and to ensure that it is able to keep pace with future developments such as the National Programme for IT (Information Technology) 10. Improving the NJR website so that information may be more easily found and enhancing communication with other key stakeholders. 10 The National Programme for IT (NPfIT) will improve patient care by creating an NHS Care Records Service to improve access to patient information across the NHS, making it easier and faster for GPs and other primary care staff to book hospital appointments for patients, providing a system for electronic transmission of prescriptions and ensuring that the IT infrastructure can meet NHS needs now and in the future 4th Annual Report 29

30 Part 1 Appendices 30 National Joint Registry

31 Appendix 1 NJR Steering Committee 2006/ NJR Steering Committee Composition As an advisory non-departmental public body, the composition of the NJRSC is: Chair 1 Orthopaedic surgeons 3 Patient Representative Groups 2 Implant manufacturer/supplier industry 2 Public health/epidemiology 1 NHS organisation management 1 Independent healthcare provider 1 Practitioner with special interest in orthopaedic care who is a GP, nurse or allied health professional (physiotherapist or occupational therapist) Membership as at 30 September 2006 Membership including members appointed under the previous constitution. Mr William Darling Professor Paul Gregg Mrs Judy Murray Mr Martyn Porter Mr Tim Wilton Ms Christine Miles Mr Michael Borroff Mr Ken Bateman Ms Christine Edwards Mr Colin Thomson Professor Alex MacGregor Chair Vice Chair British Orthopaedic Association British Hip Society British Society for Surgery of the Knee NHS Trust Management Orthopaedic Device Industry Orthopaedic Device Industry Patient Group (Arthritis Care) Patient Group (All Wales Community Health Councils) Public Health and Epidemiology Miss Carolyn Naisby Practitioner with Special Interest in Orthopaedics (from 1 July 2006) Mrs Ros Gray Independent Healthcare Sector (from 1 July to 15 September 2006) 4th Annual Report 31

32 Membership from 1 October 2006 With members appointed under new constitution as post became vacant: Mr William Darling Chair Professor Paul Gregg Orthopaedic Surgeon Vice Chair (from 31 January 2007) Mr Martyn Porter Orthopaedic Surgeon Mr Tim Wilton British Society for Surgery of the Knee (to 30 April 2007)* Mrs Patricia Durkin Representing Patients (from 1 March 2007) Mr Colin Thomson Mr Michael Borroff Miss Carolyn Naisby Miss Mary Cowern Professor Alex MacGregor Patient Group (All Wales Community Health Councils) (to 28 February 2007) Orthopaedic Device Industry Practitioner with Special Interest in Orthopaedics Representing Patients Public Health and Epidemiology Mr Anthony Lowther Orthopaedic Manufacturing/Supply Industry (From 1 October 2006) Mr Andrew Woodhead NHS Trust Management (From 4 January 2007) Mrs Patricia Cassidy Independent Healthcare Sector (From 19 April 2007) 1.3 Attenders The following have regularly attended NJRSC meetings: Mr Andy Smallwood Mr Andy Crosbie Ms Ramila Mistry Ms Kate Wortham Mrs Christine Miles NHS Purchasing and Supply Agency (PASA) now NHS Supply Chain Medicines and Healthcare Products Regulatory Agency (MHRA) Department of Health Department of Health Welsh Assembly Government * Mr Keith Tucker joins as Orthopaedic Surgeon from 1 May National Joint Registry

33 1.4 NJR Steering Committee Members Declarations of Interest Mr Michael Borroff Chair of ABHI Orthopaedics Special Interest Section and currently employed by DePuy International Ltd manufacturer of orthopaedic prostheses. Mr Ken Bateman Mrs Patricia Cassidy Miss Mary Cowern Mr William Darling Mrs Patricia Durkin Ms Christine Edwards Mrs Ros Gray Professor Paul Gregg Vice-chair of Orthopaedics Special Interest Section of Association of British Healthcare Industries (ABHI). Employed by Smith & Nephew Orthopaedics UK Ltd. Group Clinical Director, Nuffield Hospitals. None Managing Director J, M and W Darling Ltd, Managing Director Galen Pharmacy Ltd. Chair South Tyneside Standard Committee. CHKS Health Care Consultancy fee paid work and share holder. None Group Clinical Director, Nuffield Hospitals. Consultant Orthopaedic Surgeon at South Tees Hospitals NHS Trust. Unit receives research/audit funding from DePuy International Ltd, StrykerUK and Smith & Nephew plc. Orthopaedic advisor for Capio Healthcare. Professor Alexander MacGregor Professor of Chronic Disease Epidemiology, University of East Anglia. Consultant Rheumatologist at Norfolk and Norwich University Hospital NHS Trust. Mr Anthony Lowther Ms Christine Miles Mrs Judy Murray Miss Carolyn Naisby Mr Martyn Porter Mr Colin Thomson Mr J Keith Tucker Mr Tim Wilton Mr Andrew Woodhead Sales Director UK and Eire with Zimmer Ltd, manufacturer of orthopaedic prostheses. Director of Delivery & Support Unit Wales and employee of BroMorgannwg NHS Trust. Trauma and Orthopaedic Consultant, Royal Glamorgan Hospital. Consultant Physiotherapist, City Hospitals Sunderland NHS Foundation Trust. Consultant Orthopaedic Surgeon Wrightington, Wigan and Leigh NHS Trust. Work at a unit that has received financial support from DePuy International for clinical and RSA studies for Elite Plus femoral stem and C-stem. Has acted as Consultant to DePuy International for development of a hip femoral stem (C-stem AMT). None Consultant Orthopaedic Surgeon Norfolk and Norwich University Hospital NHS Trust, various sources of financial support for research undertaken by orthopaedic department. Paid royalties by Johnson and Johnson Orthopaedic more than 5 years ago for contribution to design of hip prostheses. All royalties paid to orthopaedic charity. Consultant Orthopaedic Surgeon, Derby Royal Infirmary. Chief Executive Royal National Orthopaedic Hospital NHS Trust. 4th Annual Report 33

34 Appendix 2 NJR Steering Committee Terms of Reference 11 The National Joint Registry Steering Committee (NJRSC) is responsible for: Setting the programme of work for the NJR Centre, in conjunction with the Department of Health. Ensuring that appropriate stakeholders are involved in and consulted on the work of the NJR Centre, as appropriate. Recommending any significant changes to the contract between the contractor responsible for the NJR Centre and the Department of Health, including consideration of value for money. Monitoring the codes of conduct applied to the contractor in its relationship with other key stakeholders (orthopaedic units within NHS and independent healthcare organisations and with the orthopaedic implant industry). Monitoring the delivery and quality of the work of the NJR against the contract in conjunction with the Department of Health. Monitoring the inclusion, closure and performance of orthopaedic units contributing data to the NJR. Providing advice about the performance of prostheses and best surgical practice to ministers, the Department of Health, the National Assembly for Wales, providers of orthopaedic services and, in the future, Northern Ireland Department of Health Social Services and Public. Reviewing the NJR levy on an annual basis with the Department of Health and making recommendations to ministers on the amount at which it should be set. Providing an Annual Report to ministers on the work of the NJR and, with ministerial agreement, to make the Report available in both English and Welsh. Facilitating, where appropriate, the use of NJR data for research purposes. Adhering to the terms of the Code of Practice for National Joint Registry Steering Committee Members 12 and the Code of Practice Register of Interests For further information about the NJRSC rules, publication scheme, chair and members duties and roles, code of practice for members and declaration of interests, see the NJR Steering Committee Members Handbook, available from the NJR website ( under information on the NJR Steering Committee 12 See Section 4 of the NJR Steering Committee Members Handbook 13 See Section 5 of the NJR Steering Committee Members Handbook 34 National Joint Registry

35 Appendix 3 Regional Clinical Coordinators Regional Clinical Coordinators (RCCs) Mr Peter Howard - RCC Chair South West Strategic Health Authority Mr Evert Smith Mr Nick Fiddian West Midlands Strategic Health Authority Mr David Dunlop Mr Ian D M dos Remedios North West Strategic Health Authority Mr Glyn Thomas Mr David Sochart North East Strategic Health Authority Mr John Anderson Professor Andrew McCaskie East of England Strategic Health Authority Mr Matthew Porteous Mr Godfrey Charnley South Central Strategic Health Authority Mr John Britton South East Coast Strategic Health Authority Mr Hagen Jahnich Mr Guy Selmon East Midlands Strategic Health Authority Mr Colin Esler Mr Peter Howard London Strategic Health Authority Mr Mark Rowntree Mr Gareth Scott Yorkshire and Humberside Strategic Health Authority Mr Ian Stockley Mid and West Wales Mr David Woodnutt North Wales Mr Glynne Andrew South East Wales Mr Robin Rice 4th Annual Report 35

36 Appendix 4 Regional Clinical Coordinators Network Terms of Reference The National Joint Registry Regional Clinical Coordinators Network (NJR RCC Network) RCC members have a responsibility to: Facilitate and improve NJR compliance and patient consent rates and the quality of data submitted to the NJR by individual NHS Trusts and private healthcare providers in their region 14. Establish regular interaction with relevant NJR Regional Coordinators (RCs) to achieve the RCC role. Assist the Regional Co-ordinators to encourage and support the poorly performing NHS Trusts and private healthcare providers in their region to submit the required NJR data. Provide input to determining appropriate reporting, analysis and interpretation of their region s data and the overall NJR data. Facilitate feedback of NJR data to their region s NHS Trusts and private healthcare providers orthopaedic surgeons, hospital managers and other appropriate stakeholders on a monthly to quarterly basis. Host training roadshows and regional seminars to raise awareness of the NJR and feedback information. Communicate between the regionally based hospitals/ orthopaedic units / treatment centres and the NJRSC, NJR Centre (contractor) and DH to achieve the aims of NJR. Provide continued support to the functioning of the NJR. Attend the NJR RCC Network meetings on a regular basis and contribute. Provide representation at meetings/committees for NJR at regional & national level as required. Provide representation on organising committees for NJR-related events. Note: In considering issues at national level, NJR RCC Network meeting will adopt a UK perspective, which will include taking account of differences between England, Wales and Northern Ireland, and of the status of devolved and non-devolved matters. 14 Region means SHA in England, Region in Wales and Northern Ireland 36 National Joint Registry

37 Appendix 5 NJR Services to Stakeholders NJR 1st, 2nd, and 3rd Annual Reports available on website (3rd released in 2 documents shortly after the British Orthopaedic Association (BOA) Annual Congress in September 2006) NJR website ( provides all key information about the NJR for both the public and the healthcare staff NJR StatsOnline available to NHS units and Independent Healthcare Sector units in England and Wales. Provides easy to view information about unit performance against key performance indicators and benchmarking of performance against other units, Strategic Health Authorities and nationally. NJR StatsOnline is subject to continuous review and enhancement NJR ReportsOnline launched October 2006, providing reports to key staff about operations undertaken in units, the implants used, and other, management information NJR newsletter: Joint Approach November 2006 Ability to be able to access non-patient identifiable information Bar code reader to assist data entry Detailed, real time information for the Regional Coordinators to enable them to provide direct support to units and to identify any potential problems and intervene early Patient consent Good practice guides and case studies NJR patient consent leaflet and patient information leaflets printed and distributed regularly to all units Attendance at conferences and exhibitions to inform units and staff of the role and benefits of the NJR Regional Workshops and Roadshows to inform stakeholders of service development and plans, seek unit feedback and ideas, and to allow the direct sharing of best practice between units An Information Bureau which provides information regularly to such stakeholders as NHS Supply Chain and on an ad hoc basis, including requests made under the Freedom of Information Act Surgical professions (including British Orthopaedic Association, Royal College of Surgeons), patients and public, industry (orthopaedic implant suppliers), public health specialists and epidemiologists, hospital/unit staff, NHS and independent healthcare management (including Independent Healthcare Advisory Service), NHS Supply Chain, Medicines and Healthcare Products Regulatory Agency (MHRA), NJR Steering Committee, Department of Health, Welsh Assembly, others All stakeholders Department of Health, Welsh Assembly Government, surgical professions, patients and public, hospital staff including data entry staff, NHS and independent healthcare management Surgeons, suppliers, and NJR staff in hospitals Surgical professions (including BOA and RCS), hospital staff and data entry staff Surgical professions (including BOA and RCS) Hospital data entry staff Surgeons, Hospital data entry staff. NHS and independent healthcare management Hospital and data entry staff, NHS and independent healthcare management Patients and public, hospital and data entry staff and independent healthcare management Surgeons, NHS and Independent Healthcare unit management and NJR staff, suppliers and manufacturers of implants Hospital staff, including surgeons All stakeholders, including members of the public 4th Annual Report 37

38 Appendix 6 NJR Units Not Returning Data in 2006/07 The following NHS and independent healthcare providers made no returns to NJR between 1 April 2006 and 31 March Any unit that only performs trauma hip and knee replacements are omitted from the list below. Name of Trust Barking, Havering and Redbridge Hospitals NHS Trust Bolton Hospitals NHS Trust Bromley Hospitals NHS Trust Leeds Teaching Hospitals NHS Trust Newham University Hospital NHS Trust University College London Hospitals NHS Foundation Trust Wrightington, Wigan and Leigh NHS Trust Surrey and Sussex Healthcare NHS Trust Hospital name Harold Wood Hospital The Royal Bolton Hospital Princess Royal University Hospital Leeds General Infirmary Gateway Surgical Centre University College Hospital Royal Albert Edward Infirmary Crawley Hospital 38 National Joint Registry

39 Appendix 7 Supporting Data for Figures 7.1 Supporting data for Figure 1 NJR Compliance: , based on levies from implant sales Year NJR records Levy Compliance (%) 2003/04 62, ,354 40% 2004/05 107, ,725 69% 2005/06 132, ,960 82% 2006/07 131, ,522 81% 7.2 Supporting data for Figure 2 NJR Consent: quarterly analysis of total records received and those with patient consent, 2003/ /07 Year Quarter Number of operations on NJR Number of operations on NJR with consent Consent rate (%) 2003/04 Q1 8,158 5,468 67% Q2 13,964 8,744 63% Q3 16,071 10,516 65% Q4 23,998 14,705 61% 2004/05 Q1 23,931 14,390 60% Q2 27,369 16,273 59% Q3 24,902 16,513 66% Q4 30,970 21,658 70% 2005/06 Q1 32,268 21,895 68% Q2 30,742 22,262 72% Q3 32,021 24,581 77% Q4 37,547 29,238 78% 2006/07 Q1 31,128 24,728 79% Q2 30,538 24,498 80% Q3 32,734 26,724 82% Q4 36,978 30,746 83% 4th Annual Report 39

40 7.3 Supporting data for Figure 3 NJR Linkability: analysis of total records received and those for which NHS numbers have been traced, 2003/ /07 Year Number of operations Number with NHS Number traced Linkage rate (%) 2003/04 62,191 27,807 45% 2004/05 107,172 51,580 48% 2005/06 132,578 79,733 60% 2006/07 131,378 90,502 69% 7.4 Supporting data for Figure 6 - Provider: distribution of hip and knee replacement operations by provider organisation, NJR records, for the three years 2004/05 to 2006/07 NHS Treatment Centre NHS hospitals Independent hospitals Independent Treatment Centre Total 2003/ ,669 20, , /05 3,202 69,300 32,818 1, , /06 7,294 81,535 39,635 4, , /07 7,572 86,979 30,444 6, , National Joint Registry

41 Appendix 8 Locations of Audit and Training Meetings Withybush Hospital Sandwell Hospital Royal United Hospital in Bath London Clinic (Pembrokeshire and Derwen NHS Trust) (Sandwell and West Birmingham Hospitals NHS Trust) (Bath Royal United Hospital NHS Trust) (Independent healthcare company) 4th Annual Report 41

42 Part 2 1. Introduction 42 National Joint Registry

43 Part 2 of the NJR 4th Annual Report summarises the data for hip and knee procedures carried out between 1 January to 31 December 2006 in England and Wales and entered into the NJR by 28 February The Annual Report also includes a description of outcomes after hip or knee replacement, based on procedures entered into the NJR since the start of data collection in April 2003 with, for the first time, a more extensive analysis than was possible previously. It is possible to provide analyses of outcomes, such as revision and mortality, based on the number of joint replacements that have been entered into the NJR since April 2003 and the length of time that the NJR now allows patients to be followed up after their joint replacement. The ability to determine whether patients have had a revision of their joint replacement has been further enhanced by linking the NJR data with records from the Hospital Episode Statistics (HES) database for this Report. HES is an administrative database of all NHS or privately funded admissions to NHS hospitals in England, as well as admissions of NHS funded patients treated in the independent sector. Data from the mortality registry of the Office for National Statistics (ONS) is also included in HES. The NJR provides information about the procedure, such as the surgical practice followed and the type and brand of prostheses used. The HES database provides post-operative information that is not available in the NJR, such as the length of hospital stay. Furthermore, the availability of data on all hospital admission episodes for a given patient in HES provides information about whether revision surgery has been carried out and about any other re-admission that may be related to the primary replacement procedure. The linked database therefore offers a unique opportunity to study outcomes after joint replacement that would not be available from either database alone. Based on analyses of the linked NJR-HES data on hip and knee replacements carried out in England, mortality and revision rates are presented as a function of time after surgery. The impact of patient characteristics, the type of procedure as well as the type of provider, is also explored. Furthermore, revision rates are presented for a number of frequently used prostheses brands. Special attention has been given to the outcomes after hip resurfacing and unicondylar knee replacement. The outcomes after these types of replacements have been compared against alternative types. All the comparisons described above were carried out using multivariable analyses in order to take into account that patients treated in the NHS might differ from those treated in the independent sector, or that those undergoing a particular type of joint replacement procedure, such as hip resurfacing or a unicondylar knee replacement, might differ from patients undergoing other types of procedures. A comparison of revision rates after hip and knee replacement against results presented in other national registries will also be provided. This is the first time that linkage between NJR and a hospital administrative database has been undertaken. Linkage has been performed using the HES database. HES contains record level details of procedures carried out in England that are funded by the NHS or independently funded and undertaken in the NHS. The reduced coverage of HES relative to NJR means that this linkage will not include independently funded procedures undertaken in independent sector centres, and will also exclude all procedures undertaken in Wales. In future, subject to appropriate approvals, data for patients who have undergone hip or knee replacement procedures in Wales will be included in the outcome analyses through a similar linkage process using the Patient Episode Database for Wales (PEDW), the Welsh equivalent of HES. The limited coverage of the linked database means that care should be taken in generalising the results of the outcome analyses to all hip and knee replacement procedures in England and Wales, particularly when comparing provider types. Differences in patient characteristics, procedure and provider types between the linked database and those that could not be linked are explored in the Report (Section 2). A brief description of compliance and linkage of the NJR with HES is made in Section 2, with the aim of establishing whether the quality of the data presented in the Report is such that it can be considered to be representative of joint replacement practice in England and Wales. Section 3 then gives an overview of the numbers of hip and knee procedures carried out in 2006 in England and Wales according to the type of provider (e.g. NHS, treatment centre and independent sector) and source of funding. The succeeding two Sections first present the characteristics of patients who underwent a joint replacement, the type of replacement and surgical technique used for procedures in Outcomes in terms of revision of the prostheses, mortality and length of hospital stay of the patient are then presented for procedures in the NJR-HES linked database. The results are presented separately for hip and knee replacement, with special attention given to hip resurfacing and unicondylar knee replacement. The last Section presents the types and brands of prostheses that were used in In order to establish trends over time, in each Section the data presented for 2006 are compared with NJR data entered in 2004 and 2005 (see previous Annual Reports). The text in each Section summarises the detailed results presented in Tables at the end of the Section, with appropriate references given to the relevant Table. 4th Annual Report 43

44 Part 2 2. Compliance and Linkage to the Hospital Episode Statistics Database 44 National Joint Registry

45 The level of completeness of joint procedures reported to the NJR is an important factor that determines whether the results presented in the Annual Report can be considered to be representative of joint replacement practice in England and Wales. In this section, the rate of compliance, which is defined as the proportion of all joint procedures undertaken in England and Wales in 2006 that were entered into the NJR by 28 February 2007 is presented. The outcome analyses presented in the Report were based on the procedures entered in the NJR since the start of data collection in April 2003 that were also in the HES-linked database. The characteristics of these procedures are summarised in this Section and compared to those of the procedures that could not be linked to a HES episode. 2.1 Compliance for Procedures Undertaken in 2006 A levy is collected to cover the costs of the NJR at each sale of a specific hip or knee component. A single leviable component is used for most joint procedures. A levy might not be collected in exceptional cases, such as when custom-made implants are used or when a revision operation does not involve removal and replacement of the leviable component. However, a comparison of the number of joint replacements reported to the NJR with the number of levies collected gives a reasonable approximation of the rate of compliance (case ascertainment). 2.2 Linkage of NJR Procedures to HES Episodes Hip and knee joint procedures carried out in England and Wales in the NHS as well as the independent sector have been entered into the NJR since 1 April At the time of analyses, data from HES was available for hospital admissions up to 30 September In this first undertaking of linkage between the NJR and a hospital administrative database, only those procedures carried out in England and entered in to HES were used in the linkage. In future, procedures entered into PEDW, the equivalent of HES for procedures undertaken in Wales, will also be linked with the NJR. Therefore, for this Annual Report, only those procedures undertaken between 1 April 2003 and 30 September 2006 at centres in England could potentially be linked to a HES episode. Furthermore, the HES database includes only those procedures funded by the NHS or those that are independently funded and undertaken in NHS hospitals. Consequently, the limited coverage of HES relative to the NJR means that linkage will not be possible for independently funded procedures undertaken at independent sector centres in England, or for all procedures undertaken in Wales. The total number of levies collected in England and Wales from 1 January to 31 December 2006 was 154,066 and the total number of hip and knee joint procedures reported to the NJR was 122,442. This suggests that the compliance rate was 79% for procedures carried out during the 2006 calendar year in the NHS and the independent sector. Compared with previous years, the rate of compliance has improved. The compliance rate was 77% in 2005 (124,036 procedures out of 161,735 levies collected) and 60% in 2004 (93,885 procedures out of 155,450 levies collected). 4th Annual Report 45

46 Figure 2.1 Flow chart illustrating linkage of the NJR with HES NJR 361,471 hip or knee joint replacements entered since April 2003 (England only) HES 355,480 hip or knee joint replacements since April 2003 (Procedures in the NHS and NHS funded procedures in the Independent Sector in England only) 337,908 primary procedures 23,563 revisions and other re-operations 327,557 primary procedures 27,923 revisions and other re-operations NJR HES LINKAGE 173,350 linked primary procedures 1,015 first revision procedures (excluding re-operations) identified in HES Revision rates Mortality Length of stay 46 National Joint Registry

47 2.2.1 Linkage process Figure 2.1 shows a flow chart illustrating the process of linkage of NJR procedures to HES episodes. Linkage of an NJR procedure to a HES episode was attempted using the local hospital number and NHS Trust code, provided the date of operation recorded in the NJR was within the episode start and end dates in HES. An NJR procedure was classified as being HES-linked if linkage to a HES episode was achieved using this linkage method Coverage of linked procedures All analyses of revision rates, mortality and length of stay were based on procedures that were linked to a HES episode. Revisions were used in the estimation of revision rates only if the corresponding primary procedure was included in the linked database. Therefore, only those revisions undertaken since April 2003 and recorded in HES were included. Details of how revisions were identified are given in Sections 4.2 and 5.2. An issue of concern is the potential for systematic differences between the patients whose procedures were HES-linked and those who were not HES-linked (see Table 2.1) Tables 2.2 and 2.3 show a comparison of characteristics between HES-linked and non-hes linked procedures for hip and knee joint replacements. The non-hes linked procedures in Tables 2.1 to 2.3 exclude the procedures undertaken in Wales, for which linkage was not possible. However, as funding is not a mandatory field and not completely reported, it was not possible to exclude from the non-hes linked procedures all privately funded procedures undertaken in the independent sector, for which linkage was also not possible. Of all 355,480 hip or knee replacement procedures recorded in HES between April 2003 and September 2006 and undertaken at NHS hospitals and NHS treatment centres, or undertaken in the independent sector and funded by the NHS, 187,220 (52%) were included in the linked database. However, the number of procedures linked differed between provider types. Slightly more than 70% of hip or knee replacement procedures undertaken at NHS hospitals or treatment centres were linked to a HES episode (Table 2.1). Fewer procedures were linked for Independent Sector Treatment Centres (ISTCs) (27% for hip replacements, 24% for knee replacements) and independent hospitals (6% for hip replacements, 8% for knee replacements). Therefore, the HES-linked procedures are more representative of procedures undertaken in NHS hospitals and Treatment Centres. Of all HES-linked procedures, 4% of hip (3,232) or knee (4,034) replacements were undertaken at independent hospitals (Tables 2.2 and 2.3). In comparison, of the non-hes linked procedures 60% (54,480) of hip replacements and 55% (45,147) of knee replacements were undertaken at independent hospitals. A comparison of patient characteristics between the HES-linked procedures and those that were not HES-linked showed that differences in the types of patients between these two groups of procedures were marginal (Tables 3.2 and 3.3). The differences between HES-linked and non-hes-linked procedures should be borne in mind when interpreting the results presented in the rest of the Report. 4th Annual Report 47

48 2 Compliance and Linkage to the Hospital Episode Statistics Database Table 2.1 Hip or knee joint replacement procedures carried out in England between 1 April 2003 and 30 September 2006 that were linked to a HES episode, by provider type Provider type NHS hospitals Independent hospitals NHS TCs Independent TCs All provider types Total* HES-linked procedures Total* HES-linked Total* HES-linked Total* HES-linked Total* procedures procedures procedures HES-linked procedures n % n % n % n % n % Hip joint replacements Total hip replacement using cement 55,550 40,803 73% 26,960 1,729 6% 3,157 1,948 62% 1, % 87,627 45,053 51% Total hip replacement not using cement 24,071 18,504 77% 12, % 2,270 1,724 76% 1, % 40,547 21,346 53% Hybrid or reverse hybrid total hip replacement 15,804 10,187 64% 8, % 1, % % 25,863 11,446 44% Hip resurfacing 8,247 6,074 74% 7, % % % 16,373 6,723 41% Revisions and other re-operations 11,357 8,053 71% 2, % % % 14,071 8,389 60% Total 115,029 83,621 73% 57,712 3,232 6% 7,366 4,929 67% 4,374 1,175 27% 184,481 92,957 50% Knee joint replacements Total knee replacement using cement 88,729 66,798 75% 37,377 3,057 8% 7,039 4,874 69% 4,416 1,009 23% 137,561 75,738 55% Total knee replacement not using cement 7,047 5,318 75% 3, % % % 11,575 6,517 56% Hybrid total knee replacement 1, % % % % 2,490 1,262 50% Unicondylar knee replacement 8,426 4,187 50% 5, % % % 13,986 4,531 32% Patello-femoral replacement 1, % % % % 1, % Revisions and other re-operations 7,628 5,285 69% 1, % % % 9,492 5,481 58% Total 114,358 83,232 73% 49,181 4,034 8% 8,461 5,802 69% 4,990 1,195 24% 176,990 94,263 53% * The total number of procedures presented excludes procedures undertaken in Wales as these procedures were not HES-linkable (see Section 2.2) 48 National Joint Registry

49 Table 2.2 Comparison of patient, procedure and provider type for HES-linked and non HES-linked hip replacement procedures, 1 April 2003 to 30 September 2006 * Linked to a HES episode Not linked to a HES episode Total number of procedures that were HES-linkable * Total 92,957 91, ,481 Age, years (consenting patients only) n 74,931 54, ,513 Mean (sd) 68 (12) 68 (12) 68 (12) Interquartile range Gender (consenting patients only) n n % n % n % Male 30,577 41% 22,017 40% 52,594 41% Female 44,350 59% 32,573 60% 76,923 59% Patient physical status P1 Fit and healthy 21,929 24% 29,652 32% 51,581 28% P2 Mild disease not incapacitating 55,935 60% 51,873 57% 107,808 58% P3 Incapacitating systemic disease 14,272 15% 9,435 10% 23,707 13% P4 Life threatening disease 750 1% 532 1% 1,282 1% P5 Expected to die within 24hrs 71 <1% 32 <1% 103 <1% Procedure type THR using cement 45,053 48% 42,574 47% 87,627 48% THR not using cement 21,346 23% 19,201 21% 40,547 22% Hybrid or reverse hybrid THR 11,446 12% 14,417 16% 25,863 14% Primary resurfacing 6,723 7% 9,650 11% 16,373 9% Revision 8,389 9% 5,682 6% 14,071 8% Provider type NHS hospital 83,621 90% 31,408 34% 115,029 62% Independent hospital 3,232 4% 54,480 60% 57,712 31% NHS Treatment Centre 4,929 5% 2,437 3% 7,366 4% Independent Treatment Centre 1,175 1% 3,199 3% 4,374 2% * The non HES-linked procedures exclude those procedures undertaken in Wales as these were not linkable to HES (see Section 2.2) 4th Annual Report 49

50 Table 2.3 Comparison of patient, procedure and provider type for HES-linked and non HES-linked knee replacement procedures, 1 April 2003 to 30 September 2006 * Linked to a HES episode Not linked to a HES episode Total number of procedures that were HES-linkable* Total 94,263 82, ,990 Age, years (consenting patients only) n 75,600 48, ,507 Mean (sd) 70 (10) 69 (11) 70 (10) Interquartile range Gender (consenting patients only) n n % n % n % Male 32,650 43% 21,470 44% 54,120 44% Female 42,945 57% 27,442 56% 70,387 57% Patient physical status P1 Fit and healthy 17,518 19% 22,626 27% 40,144 23% P2 Mild disease not incapacitating 61,070 65% 51,348 62% 112,418 64% P3 Incapacitating systemic disease 15,062 16% 8,451 10% 23,513 13% P4 Life threatening disease 560 1% 270 <1% 830 <1% P5 Expected to die within 24hrs 53 <1% 32 <1% 85 <1% Procedure type TKR using cement 75,738 80% 61,823 74% 137,561 78% TKR not using cement 6,517 7% 5,058 6% 11,575 7% Hybrid or reverse hybrid TKR 1,262 1% 1,228 1% 2,490 1% Unicondylar knee replacement 4,531 5% 9,455 11% 13,986 8% Patello-femoral replacement 734 1% 1,152 1% 1,886 1% Revision 5,481 6% 4,011 5% 9,492 5% Provider type NHS hospital 83,232 88% 31,126 38% 114,358 65% Independent hospital 4,034 4% 45,147 55% 49,181 28% NHS Treatment Centre 5,802 6% 2,659 3% 8,461 5% Independent Treatment Centre 1,195 1% 3,795 5% 4,990 3% * The non HES-linked procedures exclude those procedures undertaken in Wales as these were not linkable to HES (see Section 2.2) 50 National Joint Registry

51 4th Annual Report 51

52 Part 2 3. Overview of Hip and Knee Replacement Procedures, National Joint Registry

53 This summarises the numbers of hip and knee replacement procedures undertaken in England and Wales between 1 January 2006 and 31 December 2006 and entered into the NJR by 28 February The procedures are summarised according to the type of hospital or treatment centre, funding and patient characteristics. 3.1 Hospitals and Treatment Centres Participating in the NJR During the 2006 data collection period, hospitals and treatment centres (TCs) were open, and of these 393 (95%) submitted at least one hip or knee procedure into the NJR (Table 3.1). The compliance rate of 79% (determined from the number of leviable components) was lower than the 95% centre participation rate, indicating that not all procedures at the participating centres were recorded. On average, 112 hip replacements and 99 knee replacements were recorded per unit over the year, although the numbers varied from 1 procedure to over 1000 procedures (Table 3.2). 3.3 Knee Replacement Procedures Table 3.4 summarises the patient characteristics and procedure details of knee replacements according to type of provider. Independent hospitals performed more unicondylar knee replacement procedures (Figure 3.3) compared with any other type of provider. As was observed for hip replacement procedures, there were more revision procedures at NHS hospitals (6%) than at any other type of provider (3% overall). The revision procedures undertaken at NHS hospitals comprised 80% of all revision procedures. Explicit comparisons of patient characteristics for knee replacement procedures carried out in 2006 with those in 2004 and 2005 are reported in Section 5.1. Compared with previous years, there was an overall reduction in the number of centres reporting fewer than 100 procedures in a year and an increase in centres reporting more than 400 procedures in a year (Figure 3.1). 3.2 Hip Replacement Procedures This section summarises the patient characteristics and procedure details of hip replacements according to the type of provider (Table 3.2). 93% of patients at independent hospitals and independent sector Treatment Centres, compared with 81% at NHS units, were graded as fit and healthy or with mild disease according to the American Society of Anaesthesiologists (ASA) grade system. Nearly all (98%) of procedures undertaken at ISTCs were primary procedures and over half of these were cemented procedures. Independent hospitals performed more primary resurfacing procedures (Figure 3.2) compared with other provider types. There were more revision procedures undertaken at NHS hospitals (12%) than at any other type of provider (5% overall). The revision procedures undertaken at NHS hospitals comprise 81% of all revision procedures. Explicit comparisons of patient characteristics for hip replacement procedures carried out in 2006 with those in 2004 and 2005 are reported in Section This is for the calendar year 1 January to 31 January th Annual Report 53

54 Figure 3.1 Number of participating hospitals by number of procedures, Hip procedures Number of hospitals < Number of operations 140 Knee procedures Number of hospitals < Number of operations 54 National Joint Registry

55 100% 90% Figure 3.2 Primary hip procedures by provider type 80% 70% Percentage 60% 50% 40% 30% Cemented 20% Cementless 10% Hybrid 0 NHS Hospital NHS Treatment Centre Independent Hospital Independent Treatment Centre Resurfacing 100% 90% Figure 3.3 Primary knee procedures by provider type 80% 70% Percentage 60% 50% 40% 30% 20% Hybrid Cemented Patello-Femoral 10% Cementless 0 NHS Hospital NHS Treatment Centre Independent Hospital Independent Treatment Centre Unicondylar 4th Annual Report 55

56 3 Overview of Hip and Knee Replacement Procedures, 2006 Table 3.1 Total number of hospitals and Treatment Centres in England and Wales able to participate in the NJR and proportion actually participating in Total (England and Wales) Participating in the NJR 2006 n % NHS hospitals % England Wales Independent hospitals % England Wales 6 6 NHS Treatment Centres % England Wales 0 0 Independent Treatment Centres % England Wales % 56 National Joint Registry

57 Table 3.2 Number of participating hospitals according to number of procedures entered over the 2006 data collection period 2006 Number of procedures recorded in NJR in 2006 Total number of hospitals < Average number per unit Min Max All Operations Hospitals entering hip replacements ,253 Hospitals entering knee replacements ,388 Primary Operations Hospitals entering primary hip replacements ,167 Hospitals entering primary knee replacements ,352 Total number of hospitals Average number per unit Min Max Revision/Re-operation Hospitals entering revision/re-operation hip replacements Hospitals entering revision/re-operation knee replacements Number of procedures recorded in NJR in 2005 Total number of hospitals < Average number per unit Min Max All Operations Hospitals entering hip replacements ,226 Hospitals entering knee replacements ,429 Primary Operations Hospitals entering primary hip replacements ,037 Hospitals entering primary knee replacements ,396 Total number of hospitals Average number per unit Min Max Revision/Re-operation Hospitals entering revision/re-operation hip replacements Hospitals entering revision/re-operation knee replacements th Annual Report 57

58 Table 3.3 Patient characteristics and procedure details according to type of provider for hip procedures in Provider type NHS hospitals Independent hospitals NHS Treatment Centres Independent Treatment Centres Total n % n % n % n % n % Total 39,924 n/a 15,585 n/a 3,343 n/a 2,604 n/a 61,456 n/a Patient physical status P1 Fit and healthy 7,244 18% 5,062 32% % % 13,689 22% P2 Mild disease, not incapacitating 24,992 63% 9,344 60% 2,155 64% 1,896 73% 38,387 62% P3 Incapacitating systemic disease 7,289 18% 1,119 7% % 113 4% 8,903 14% P4 Life threatening disease 370 1% 49 0% 13 0% 2 0% 434 1% P5 Not expected to survive 24 hours 29 0% 11 0% 2 0% 1 0% 43 0% Procedure type Primary procedure 34,985 88% 14,694 94% 3,117 93% 2,556 98% 55,352 90% Total hip replacement using cement 16,585 47% 6,101 42% 1,141 37% 1,486 58% 25,313 46% Total hip replacement not using cement 9,961 28% 4,375 30% 1,217 39% % 16,416 30% Hybrid or reverse hybrid total replacement 5,372 15% 2,001 14% % 186 7% 8,027 14% Primary resurfacing 3,067 9% 2,217 15% 291 9% 21 1% 5,596 10% Revision procedure % 872 6% 223 7% 39 1% 5,821 9% Hip Single Stage Revision % % % 4,953 85% Hip Revision (Stage 1 of 2) 306 7% 32 4% 3 1% 2 5% 343 6% Hip Revision (Stage 2 of 2) 396 8% 56 6% 9 4% 5 13% 466 8% Hip Girdlestone 54 1% 3 0% 1 0% 1 3% 59 1% Re-operation other than revision 252 1% 19 0% 3 0% 9 0% 283 0% Bilateral or unilateral Bilateral 100 0% 164 1% 2 0% 2 0% 268 0% Unilateral 39, % 15,421 99% 3, % 2, % 61, % Primary procedure complexity ** Hip primary 33,146 83% 14,260 91% 2,983 89% 2,518 97% 52,902 86% Hip complex primary 1,839 5% 434 3% 134 4% 38 1% 2,445 4% Funding ** NHS funding 32,911 96% 2,772 21% 2,957 99% 2, % 41,110 78% Independent funding 1,212 4% 10,163 79% 25 1% 0 0% 11,395 22% Not recorded 5,801 n/a 2,650 n/a 361 n/a 134 n/a 8,946 n/a ** Optional field 58 National Joint Registry

59 Table 3.4 Patient characteristics and procedure details according to type of provider for knee procedures in Provider type NHS hospitals Independent hospitals NHS Treatment Centres Independent Treatment Centres Total n % n % n % n % n % Total 40,964 n/a 13,030 n/a 4,002 n/a 2,990 n/a 60,986 n/a Patient physical status P1 Fit and healthy 5,987 15% 3,321 25% % % 10,515 17% P2 Mild disease, not incapacitating 27,441 67% 8,643 66% 2,920 73% 2,243 75% 41,247 68% P3 Incapacitating systemic disease 7,271 18% 1,024 8% % 129 4% 8,899 15% P4 Life threatening disease 239 1% 32 0% 14 0% 1 0% 286 0% P5 Not expected to survive 24 hours 26 0% 10 0% 3 0% 0 0% 39 0% Procedure type Primary procedure 38,245 93% 12,495 96% 3,909 98% 2,948 99% 57,597 94% Total knee replacement using cement 32,096 84% 9,502 76% 3,287 84% 2,741 93% 47,626 83% Total knee replacement not using cement 2,542 7% 1,035 8% % 133 5% 4,088 7% Hybrid total replacement 356 1% 271 2% 70 2% 5 0% 702 1% Unicondylar knee replacement 2,846 7% 1,475 12% 150 4% 62 2% 4,533 8% Patello-femoral replacement 405 1% 212 2% 24 1% 7 0% 648 1% Revision procedure 2,445 6% 497 4% 84 2% 22 1% 3,048 5% Single Stage Revision 1,763 72% % 68 81% 17 77% 2,242 74% Revision (Stage 1 of 2) % 40 8% 6 7% 3 14% % Revision (Stage 2 of 2) % 60 12% 10 12% 2 9% % Amputation 2 0% 1 0% 0 0% 0 0% 3 0% Conversion to arthrodesis 11 0% 2 0% 0 0% 0 0% 13 0% Re-operation other than revision 274 1% 38 0% 9 0% 0 0% 321 1% Bilateral or unilateral Bilateral 266 1% 350 3% 0 0% 2 0% 618 1% Unilateral 40,698 99% 12,680 97% 4, % 2, % 60,368 99% Primary procedure complexity ** Knee primary 36,923 90% 12,220 94% 3,822 96% 2,927 98% 55,893 92% Knee complex primary 1,322 3% 271 2% 87 2% 21 1% 1,701 3% Funding ** NHS funding 33,853 98% 3,507 33% 3, % 2, % 43,780 85% Independent funding 623 2% 7,193 67% 12 0% 0 0% 7,828 15% Not recorded 6,488 n/a 2,330 n/a 396 n/a 164 n/a 9,378 n/a ** Optional field 4th Annual Report 59

60 Part 2 4. Hip Replacement Procedures 60 National Joint Registry

61 60% Figure 4.1 Type of primary hip replacement procedure undertaken between 2004 and % 40% Percentage 30% 20% THR using cement THR not using cement 10% Hybrid or reverse hybrid THR Q Q Q Q Q Q Q Q Q Q Q Q4 Hip resurfacing 4.1 Hip Replacement Procedures, 2006 This section summarises the patient characteristics and surgical details of all 55,352 primary, 5,821 revision and 283 re-operation hip replacement procedures undertaken between 1 January and 31 December 2006 and entered into the NJR by 28 February Fields for which data entry is optional are indicated in the tables of results. All optional fields, apart from untoward intra-operative events, were reported in more than 80% of procedures Patient characteristics Age and gender were recorded only for those patients who gave consent (82%) for their personal identifiers to be entered into the NJR. The average age was 68 years and about 60% of the patients were female (Table 4.1). On average, female patients were older than male patients at the time of their primary hip replacement (69 years vs 66 years respectively, Table 4.2). Patients undergoing a resurfacing procedure were the youngest at an average age of 55 years (See Figure 4.2) Primary hip replacement procedures, 2006 Almost half of the 55,352 primary hip replacement procedures undertaken in 2006 were cemented total hip replacements (THR) and 5,596 (10%) were hip resurfacing procedures (Table 4.1). Compared with previous years, there has been a reduction in the use of cemented THR procedures and hybrid or reverse hybrid procedures and a corresponding increase in the use of cementless procedures (Figure 4.1). The greatest changes were a reduction in cemented procedures from 53% during 2004 to 48% during 2006, and an increase in cementless procedures from 21% during 2004 to 30% during th Annual Report 61

62 60% 50% Female Figure 4.2 Age and gender for primary hip replacement patients in % Percentage 30% 20% <55 years 10% years years 0 Cemented THR Uncemented THR Hybrid THR Hip Resurfacing >75 years According to the American Society of Anaesthesiologists (ASA) grade system, about a quarter of patients undergoing a primary hip replacement in 2006 were graded as being fit and healthy prior to surgery. The single largest indication recorded for surgery was osteoarthritis, recorded in 94% of procedures. Compared to previous years, the patient characteristics described above have largely remained unchanged. However, there has been an increase in hip operations in patients with mild or incapacitating disease. For example, procedures in patients with mild disease increased from 57% in 2004 to 63% in Surgical techniques The surgical techniques used in procedures undertaken in 2006 are summarised in Table 4.3. Patients were mainly positioned laterally. The lateral position was used more frequently in hybrid and resurfacing procedures than in cemented and cementless procedures. The most frequently used incision approach was posterior for cementless, hybrid and resurfacing procedures and lateral for cemented procedures. Use of minimally invasive surgery (MIS) was greatest in cementless procedures, although it was used in less than a tenth of all procedures. Compared with previous years, there has been an increase in the use of a lateral patient position, a posterior incision approach and a reduction in the use of cemented prostheses. The use of a lateral patient position increased from 83% in 2004 to 88% in 2006, while the use of a posterior incision approach increased from 39% in 2004 to 46% in The reduction in the use of cemented stems from 77% in 2004 to 69% in 2006 and from 56% to 47% in the use of cemented cups is consistent with the reduction seen in the overall number of cemented procedures (Figure 4.1) Thromboprophylaxis The most frequently prescribed chemical method was low molecular weight heparin, and TED stockings were the most frequently prescribed mechanical method (Table 4.4). Each of these methods was prescribed for use after about 60% of all procedures. There has been an increase in procedures in which both chemical and mechanical methods are prescribed from 50% in 2004 to 61% in The increase can partly be attributed to similar changes in the prescription of low molecular weight heparin, which increased from 50% to 60%, and TED stockings which increased from 53% to 61%. A marginal increase was also seen in the prescription of a foot pump from 24% in 2004 to 28% in National Joint Registry

63 60% 50% Male Figure 4.2 (continued) Age and gender for primary hip replacement patients in % Percentage 30% 20% <55 years 10% years years 0 Cemented THR Uncemented THR Hybrid THR Hip Resurfacing >75 years Untoward intra-operative events Untoward intra-operative events were reported in 1% of procedures (Table 4.5). Completion of the data field requesting these events was not mandatory and the default option, which held when the field was not completed, was that no untoward intra-operative event occurred. Of the 625 untoward events reported, about a third were calcar cracks. Compared with previous years, the pattern of untoward intra-operative events has largely remained the same Hip revisions, 2006 A total of 5,821 hip revision procedures were reported. This includes 466 (8%) procedures that were Stage 2 of a two-stage revision process and which have been excluded from the rest of the section. Of the remaining 5,355 procedures (Table 4.6), 4,953 (93%) were single stage revision procedures, 343 (6%) were Stage 1 of a two-stage process and 59 (1%) were Girdlestone type procedures. Compared with previous years, there has been no change in the types of revision procedures carried out Patient characteristics Table 4.6 summarises patient characteristics for the 5,355 hip revision procedures (excluding Stage 2 procedures) undertaken in Compared with previous years, the patient characteristics shown in Table 4.6 have largely remained unchanged. However, changes were seen in the general medical condition of patients and indications for revision. There was a reduction in patients who were fit and healthy prior to surgery, with a corresponding increase in patients with mild or incapacitating disease. For example, procedures in patients with mild disease increased from 57% in 2004 to 59% in A similar pattern was seen in primary hip replacement procedures. With regard to the indication for surgery among two-stage revision procedures (Table 4.7), there was, for example, a reduction in revision for aseptic loosening from 44% in 2004 to 22% in th Annual Report 63

64 Components removed and components used Both the acetabular and femoral components were removed in over half of all revision procedures (Table 4.8). However, comparing the different types of revision procedures indicates that both components were more likely to be removed during a two-stage revision process or with a hip Girdlestone type procedure than during a single stage revision. About a third of the femoral or acetabular components used during single stage revision procedures were cemented (Table 4.9) Hip re-operations other than revision, 2006 A total of 341 re-operation procedures following an initial hip replacement were recorded. Of all re-operations, 15% involved socket augmentation and 15% were reported as wound exploration (Table 4.10). 60% of the re-operations had other descriptions outside of the list of options given and included closed reduction of dislocation, exchange of femoral head and application of a posterior lipped augmentation device (PLAD) used in socket augmentation. The characteristics of patients undergoing a hip re-operation in 2006 are shown in Table The average age of the patients was 71 years and over half of the patients were female (58%). A physical status of fit and healthy or mild disease, not incapacitating was declared for 68% of hip patients. 4.2 Outcomes Following Primary Hip Replacement, This section presents analyses of revision and mortality rates as well as length of stay for primary hip replacement procedures, with special attention given to revision of hip resurfacing procedures. The analyses are based on data on hip replacement procedures undertaken between 1 April 2003 and 30 September 2006 that were linked to an episode in the HES database. As explained in Section 2.2, the linked procedures were those undertaken in England, and mainly in NHS hospitals. A description of the linkage process, as well as the patient characteristics of the linked procedures in also included in Section Revision This section summarises survival to revision of implants used in primary hip replacement procedures that were linked to a HES procedure. All 76,576 primary hip replacement procedures in the NJR that were undertaken between 1 April 2003 and 30 September 2006 and linked to a HES episode that was also defined as a primary hip replacement procedure were identified. Of the linked primary hip replacement procedures, 72,534 (95%) were undertaken at NHS hospitals and NHS treatment centres and 4,042 (5%) were undertaken in the independent sector. In HES, primary hip replacements for the patients with linked procedures were identified using the following OPCS-4 16 procedure codes: W371 Primary total prosthetic replacement of hip joint using cement W381 Primary total prosthetic replacement of hip joint not using cement W391 Primary total prosthetic replacement of hip joint not elsewhere classified W581 Primary resurfacing arthroplasty of joint Some patients had two primary hip replacement procedures, one on each side, which occurred on different dates and were both linked to a HES record. In such cases, to avoid including a patient twice in the linked database, only the earliest primary procedure was retained. For each patient with a linked primary procedure, all hospital episodes recorded in HES succeeding the primary procedure were identified. From these succeeding episodes, the first hip revision that occurred on the same side as the primary was then identified in HES. Where the side of the primary or the revision was not recorded, the first revision that occurred after the primary procedure was assumed to be a revision of that primary. In HES, revision procedures were identified using the procedure codes W373, W383, W393 and W582 (with Z843 hip joint) indicating revision of a cemented, cementless, unclassified and hip resurfacing primary procedure, respectively. In addition, revision codes indicating conversion from one type of replacement to another, as well as attention to the replacement joint in which there was renewal of the prosthesis, were also identified as revisions. Codes indicating other types of attention to the hip replacement joint, such as correction of displacement of prosthesis, were considered to be re-operations and were not included. Using the revisions identified in HES as described above, revision rates were then estimated for various patient characteristics, as well as procedure and provider types. The revision rates were estimated using the Kaplan-Meier survival analysis method that allows prostheses that are followed up for unequal lengths of time after implant to be included. 16 Office of Population, Censuses and Surveys: Classification of Surgical Operations and Procedures, 4th Revision 64 National Joint Registry

65 Figure 4.3 Revision rate estimates for HES-linked primary hip replacement procedures, Analysis time (years from operation) Revision rate (95% Cl) Procedures type (n) 3 months 1 year 3 years Cemented THR Cemented (41,232) Cementless (19,022) Hybrid (10,120) Resurfacing (6,202) 0.2% (0.1% 0.2%) 0.5% (0.5% 0.7%) 0.3% (0.2% 0.4%) 0.9% (0.7% 1.2%) 0.3% (0.3% 0.4%) 1.0% (0.8% 1.1%) 0.7% (0.5% 0.9%) 1.6% (1.3% 2.0%) 0.9% (0.7% 1.1%) 1.9% (1.6% 2.3%) 1.4% (1.1% 1.9%) 2.4% (2.0% 3.0%) Hybrid THR Cementless THR Hip Resurfacing Procedure type The overall revision rate following primary hip replacement was 0.7% (95% CI 0.6% 0.7%) at 1 year and 1.3% (95% CI 1.2% 1.5%) at 3 years. Figure 4.3 shows estimates of implant survival to revision by procedure type, together with revision rates at 3 months, 1 year and 3 years following primary hip replacement. Resurfacing procedures have a statistically significantly higher rate of revision compared to THR procedures, a difference that is already apparent within the first 3 months after replacement. Analyses of longer term survival, which has not been possible in this Report on account of the limited follow-up time allowed by the NJR, is necessary to establish the comparative performance of hip resurfacing in the long term. 4th Annual Report 65

66 Kaplan-Meier survival estimate Age <55 years Age 55+ years Figure 4.4 Revision rate estimates by age for HES-linked primary hip replacement procedures, Cemented THR Hybrid THR Cementless THR Analysis time (years from operation) Analysis time (years from operation) Hip Resurfacing 1 year revision rates (95% Cl) [n=8,982] 1 year revision rates (95% Cl) [n=67,593] Cemented THR Cementless THR Hybrid THR Hip resurfacing 0.4% (0.2% - 0.9%) 0.7% (0.4% - 1.1%) 0.6% (0.3% - 1.3%) 1.2% (0.9% - 1.7%) Cemented THR Cementless THR Hybrid THR Hip resurfacing 0.3% (0.3% - 0.4%) 1.0% (0.9% - 1.2%) 0.7% (0.5% - 0.9%) 2.0% (1.6% - 1.7%) Age and gender A difference in age and gender distribution was found among primary hip replacement procedures undertaken in 2006 (Section 4.1.1). The influence of these two factors on revision rates following primary hip replacement is explored in this section. Figure 4.4 shows revision rates for patients aged less than 55 years and those aged 55 or older, separately. The only age-related difference in revision rates was observed in patients who underwent hip resurfacing. In these patients, the revision rate was higher in patients aged 55 and over and this difference was pronounced in the early postoperative period. Figure 4.5 shows revision rates for female and male patients separately. The revision rate for hip resurfacing procedures was statistically significantly higher than that for other procedure types among female patients. Table 4.12 shows the results of a multivariable analysis in which the impact of patient age, gender and physical status, as well as procedure and provider type on 1-year revision rates was assessed. The crude rate is not adjusted for other factors. For example, the crude revision rates shown for the procedure types do not take into account that patients undergoing hip resurfacing are on average younger than those undergoing other types of procedures. A multivariable model can be used to adjust simultaneously for important confounding factors, such as age and gender, when comparing rates for different procedure types. The hazard ratio for a given factor level in Table 4.12 is a ratio of the risk of revision within 1 year after replacement among those implants that have not yet failed, relative to the risk for the reference level (shown by a hazard ratio of 1) of that factor. For example, the hazard ratio shown for hip resurfacing compares the risk of revision within 1 year for a patient who undergoes a resurfacing procedure relative to that of another patient of the same age, gender and physical status who undergoes a cemented procedure. Likewise, the hazard ratio shown for hybrid hip replacements compares the risk of revision for hybrid procedures relative to cemented procedures. The hazard ratios presented in Table 4.12 suggest that procedure type is the most influential factor on implant survival following primary hip replacement. Hip resurfacing procedures have statistically significantly higher revision rates than cemented THR procedures, after adjusting for age, gender, ASA grade and provider type. The results shown in Figures 4.4 and 4.5 suggest that a large number of the failures in hip resurfacing procedures contributing to their relatively higher revision rate occur in older female patients. 66 National Joint Registry

67 Kaplan-Meier survival estimate Female Male Figure 4.5 Revision rate estimates for male and female patients with HES-linked primary hip replacement procedures Cemented THR Hybrid THR Cementless THR Analysis time (years from operation) Analysis time (years from operation) Hip Resurfacing 1 year revision rates (95% Cl) [n=45,680] 1 year revision rates (95% Cl) [n=30,868] Cemented THR 0.3% (0.3% - 0.4%) Cemented THR 0.6% (0.5% - 0.7%) Cementless THR 1.1% (0.9% - 1.3%) Cementless THR 1.1% (0.9% - 1.4%) Hybrid THR 0.6% (0.5% - 0.9%) Hybrid THR 0.9% (0.7% - 1.3%) Hip resurfacing 2.1% (1.5% - 2.8%) Hip resurfacing 1.6% (1.2% - 2.1%) Comparison of revision rates with other national registries A comparison of revision rates seen in the NJR with those reported in other national registries showed that the rates reported in the NJR were generally lower than those reported elsewhere 17,18,19. However, there were differences in the definition of what a revision is across registries, with some registries including re-operations as revisions. Furthermore, revisions were specified for different time periods and it has been shown in that revision rates have improved significantly over time Revision rates for the most frequently used implant brands Figures 4.6 and 4.7 show revision rates for cemented and cementless stems, respectively for the most frequently used brands. There were no statistically significant differences among the different brands of stems. 17 Australian Orthopaedic Association National Joint Replacement Registry Annual Report /aoanjrrreport_2006.pdf 18 The Norwegian Arthroplasty Register, The Swedish Hip Arthroplasty Register Annual Report th Annual Report 67

68 Kaplan-Meier survival estimate Figure 4.6 Revision rate estimates for the five most commonly used hip cemented stem brands, Analysis time (years from operation) Revision rate (95% Cl) Brand (n) 3 months 1 year 3 years C-Stem C-Stem (4,826) 0.1% (0.06% - 0.3%) 0.4% (0.3% - 0.7%) 1.2% (0.8% - 1.8%) Exeter Charnley (7,835) CPT (3,081) Exeter (23,725) Stanmore Modular (1,260) 0.1% (0.06% - 0.2%) 0.3% (0.1% - 0.5%) 0.2% (0.1% - 0.2%) 0.2% (0.07% - 0.6%) 0.3% (0.2% - 0.4%) 0.7% (0.4% - 1.1%) 0.4% (0.3% - 0.5%) 0.3% (0.1% - 0.8%) 0.8% (0.6% - 1.2%) 1.0% (0.7% - 1.6%) 0.8% (0.6% - 1.1%) 1.3% (0.4% - 4.3%) Charnley Stanmore Modular CPT Kaplan-Meier survival estimate Figure 4.7 Revision rate estimates for the three most commonly used hip cementless stem brands, Analysis time (years from operation) Revision rate (95% Cl) Brand (n) 3 months 1 year 3 years Corail ABG II (1,091) Corail (5,230) Furlong (5,927) 0.9% (0.5% - 1.7%) 0.3% (0.2% - 0.5%) 0.6% (0.4% - 0.8%) 1.2% (0.7% - 2.1%) 0.6% (0.4% - 0.9%) 1.1% (0.9% - 1.5%) 1.6% (0.9% - 2.7%) 1.2% (0.8% - 1.9%) 2.2% (1.7% - 2.8%) Furlong HAC ABG II 68 National Joint Registry

69 Kaplan-Meier survival estimate Figure 4.8 Revision rate estimates for the five most commonly used hip cemented cup brands, Analysis time (years from operation) Revision rate (95% Cl) Brand (n) 3 months 1 year 3 years Charnley Charnley (5,010) 0.06% (0.02% - 0.2%) 0.2% (0.1% - 0.4%) 0.8% (0.5% -1.3%) Contemporary Charnley Ogee (3,921) 0.1% (0.05% - 0.3%) Contemporary (6,424) 0.2% (0.2% - 0.4%) Eliet Plus Ogee (6,013) 0.08% (0.03% - 0.2%) Exeter Duration (3,712) 0.3% (0.1% - 0.5%) 0.4% (0.2% - 0.6%) 0.4% (0.2% - 0.6%) 0.3% (0.2% - 0.4%) 0.5% (0.3% - 0.8%) 0.9% (0.6% -1.4%) 0.9% (0.6% -1.5%) 1.0% (0.6% -1.6%) 1.3% (0.7% - 2.3%) Exeter Duration Charnley Ogee Elite Plus Ogee 4th Annual Report 69

70 Kaplan-Meier survival estimate Figure 4.9 Revision rate estimates for the three most commonly used hip cementless cup brands, Analysis time (years from operation) Revision rate (95% Cl) Brand (n) 3 months 1 year 3 years CSF CSF (5,692) 0.6% (0.4% - 0.8%) 1.1% (0.8% - 1.4%) 2.1% (1.6% - 2.7%) Duraloc Duraloc (2,991) Trilogy (4,104) 0.5% (0.3% - 0.8%) 0.6% (0.4% - 0.9%) 0.8% (0.5% - 1.2%) 1.1% (0.8% - 1.4%) 1.6% (1.1% - 2.3%) 1.5% (1.1% - 2.1%) Trilogy Resurfacing procedures This section presents results of detailed analyses of hip resurfacing procedures, focusing on revision rates for the most commonly used brand, the causes of failure compared with other types of primary hip replacement, as well as revision of procedures where a large modular head was used with a regular stem and a resurfacing cup. Figure 4.10 shows revision rates for the Birmingham Hip Resurfacing (BHR) prosthesis, which is the most frequently used brand. There were insufficient procedures performed to allow reliable estimates of revision rates to be obtained for other brands of hip resurfacing prostheses Causes of failure Figure 4.3 showed that hip resurfacing procedures have a higher rate of revision, particularly in the early post-operative period. The causes of failure for the different primary procedure types are shown in Table The cause of failure for each primary procedure was determined from the indication for surgery for the corresponding revision procedure. The most common causes of failure for hip resurfacing procedures were peri-prosthetic fractures and pain. In comparison, the most common causes of failure for cemented THR procedures were aseptic loosening and infection Use of large modular heads with regular stems and resurfacing cups Recent trends (see Section 6.1.4) show an increase in the use of a resurfacing cup with a conventional stem and a large metal-on-metal modular femoral head. However, the number of procedures carried out is insufficient to allow a reliable estimation of revision rates to be made. 70 National Joint Registry

71 Kaplan-Meier survival estimate Figure 4.10 Revision rate estimates for the most commonly used brand of hip resurfacing prostheses, Analysis time (years from operation) Revision rate (95% Cl) Brand (n) 1 year 2 years 3 years BHR (4,148) 1.2% (0.9% - 1.6%) 1.6% (1.3% - 2.2%) 1.8% (1.4% - 2.4%) Mortality This section summarises mortality rates for primary hip replacement patients for all 76,317 procedures undertaken between 1 April 2003 and 30 June 2006 that were linked to a HES record. At the time of analysis, dates of death were only available up to 30 June 2006 and only those procedures undertaken up to this date could therefore be analysed. The mortality rate of primary hip replacement patients was 1.9% (95% CI 1.8% - 2.0%) at 1 year and 5.0% (95% CI 4.7% - 5.3%) at 3 years. Mortality rates at 1 year following primary hip replacement were compared with that of the general population of England and Wales, using age and gender adjusted standardised mortality ratio (SMR) (Table 4.14). The comparison showed that mortality among hip replacement patients is less than half of that observed in a general age-matched and sex-matched population, with the overall SMR (comparison of observed and expected deaths) being 0.46 (95% CI ). Table 4.15 shows the results of a multivariable analysis of mortality at 1 year (see Section for an explanation of multivariable analyses and hazard ratios). After adjusting for confounding factors, mortality at 1 year remains higher for older patients and those in a poor general medical condition, but lower for female than male patients. Mortality at 1 year following primary hip resurfacing is lower than that following cemented total hip replacement after adjusting for age, gender and patient physical status. However, most patients undergoing hip resurfacing are under 65 years of age and are graded as fit and healthy (see Tables 4.1 and 4.2), which complicates interpretation of the results. 4th Annual Report 71

72 Kaplan-Meier survival estimate Figure 4.11 Mortality for patients with and those without any thromboprophylaxis prescribed at the time of primary hip replacement, Analysis time (months from operation) Mortality rate (95% Cl) 3 months 6 months 1 year None prescribed None prescribed [n=1,446] Chemical only [n=19,484] 0.7% (0.4% - 1.3%) 0.7% (0.6% - 0.9%) 1.1% (0.6% - 1.7%) 1.2% (1.0% - 1.3%) 1.9% (1.3% - 2.8%) 1.9% (1.7% - 2.1%) Mechanical only Chemical only Both types Mechanical only [n=13,183] 0.8% (0.6% - 1.0%) 1.2% (1.0% - 1.4%) 2.0% (1.8% - 2.3%) Both types [n=42,204] 0.7% (0.6% - 0.8%) 1.1% (1.0% - 1.2%) 1.8% (1.7% - 2.0%) Thromboprophylaxis Mortality rates up to 1 year following primary hip replacement were compared between patients with different types of thromboprophylaxis prescribed at the time of surgery, including those for whom none was prescribed. There were no statistically significant differences in mortality between the different types prescribed (Figure 4.11) Length of stay This section presents results for the analysis of length of hospital stay following admission for a primary hip replacement procedure among procedures linked to a HES episode. Table 4.16 gives the average length of stay for patients with particular characteristics, as well as by procedure and provider type. The average length of stay was calculated as the total number of bed days divided by the number of patients. The average length of stay following primary hip replacement was 9.1 days. Length of stay is influenced by several factors, including those shown in Table Valid comparison of length of stay across procedure type requires adjustment for differences in patient characteristics. For example, patients who undergo hip resurfacing procedures are on average younger than those who undergo total hip replacement, and this difference in average age should be taken into account 72 National Joint Registry

73 in comparing the length of stay across different procedure types. The difference in average length of stay shown for each factor in Table 4.16 is adjusted for the other factors in the table. Patients who underwent a primary hip resurfacing procedure stayed in hospital an average 6.3 days, compared with 9.7 days following a cemented THR a difference of about 3 days. The adjusted difference between hip resurfacing and cemented THR procedures in the average length of stay was 1 day. The smaller difference seen after adjustment suggests that differences in length of stay between procedure types are, at least in part, related to patient characteristics and provider types. The average length of stay is also shown separately for male and female patients and in terms of whether they were younger (< 55 years) and older (> 55 years) (Table 4.17). Across the four groups, older patients stayed, on average, 2 days longer than younger patients, while female patients stayed, on average, 1 day longer than male patients. 4th Annual Report 73

74 4 Hip Replacement Procedures Table 4.1 Patient characteristics for primary hip replacement procedures in 2006, according to type of procedure 2006 Patient procedure Total replacement using cement Total replacement not using cement Hybrid or reverse hybrid total replacement Primary resurfacing Total Total 25,313 16,416 8,027 5,596 55,352 Age, years (consenting patients only) n* 20,720 13,588 6,578 4,539 45,425 Mean (sd) 73 (9) 65 (11) 68 (11) 55 (9) 68 (11) Interquartile range n % n % n % n % n % Gender (consenting patients only) n* 20,776 n/a 13,611 n/a 6,587 n/a 4,552 n/a 45,526 n/a Female 13,677 66% 7,742 57% 4,097 62% 1,634 36% 27,150 60% Male 7,099 34% 5,869 43% 2,490 38% 2,918 64% 18,376 40% Patient physical status P1 Fit and healthy 4,020 16% 4,366 27% 1,609 20% 2,818 50% 12,813 23% P2 Mild disease not incapacitating 17,000 67% 9,968 61% 5,264 66% 2,577 46% 34,809 63% P3 Incapacitating systemic disease 4,083 16% 1,985 12% 1,096 14% 188 3% 7,352 13% P4 Life threatening disease 202 1% 82 0% 52 1% 10 0% 346 1% P5 Expected to die within 24hrs 8 0% 15 0% 6 0% 3 0% 32 0% Indications for surgery ** Osteoarthritis 23,920 94% 15,294 93% 7,387 92% 5,380 96% 51,981 94% Ankylosing spondylitis 73 0% 71 0% 14 0% 21 0% 179 0% Avascular necrosis 654 3% 559 3% 284 4% 128 2% 1,625 3% Congenital dislocation/dysplasia of hip 136 1% 339 2% 167 2% 168 3% 810 1% Failed hemi-arthroplasty 74 0% 31 0% 26 0% 0 0% 131 0% Failed internal fixation 187 1% 155 1% 89 1% 5 0% 436 1% Fractured acetabulum 43 0% 42 0% 39 0% 17 0% 141 0% Fractured neck of femur 397 2% 241 1% 139 2% 3 0% 780 1% Other hip trauma 24 0% 51 0% 12 0% 16 0% 103 0% Other inflammatory arthropathy 107 0% 79 0% 52 1% 13 0% 251 0% Perthes 18 0% 58 0% 26 26% 19 0% 121 0% Previous arthrodesis 6 0% 8 0% 8 0% 0 0% 22 0% Infection 14 0% 19 0% 11 0% 5 0% 49 0% Psoriatic arthropathy 10 0% 14 0% 7 0% 1 0% 32 0% Seropositive rheumatoid arthritis 233 1% 100 1% 74 1% 14 0% 421 1% Slipped upper femoral epiphesis 22 0% 71 0% 42 1% 52 1% 187 0% Other 319 1% % 106 1% 69 1% 657 1% Side Bilateral 48 0% 130 1% 26 0% 64 1% 268 0% Left, unilateral 11,304 45% 7,527 46% 3,646 45% 2,590 46% 25,067 45% Right, unilateral 13,961 55% 8,759 53% 4,355 54% 2,942 53% 30,017 54% * Age and gender reported for consenting patients only (82% of primary procedures) ** More than one indication may be recorded 74 National Joint Registry

75 Table 4.2 Age and gender for primary hip replacements in Patient procedure Total replacement using cement Total replacement not using cement Hybrid or reverse hybrid total replacement Primary resurfacing Overall Average age by gender * Female n 13,643 n/a 7,729 n/a 4,090 n/a 1,628 n/a 27,090 n/a Mean (sd), interquartile range 73 (9) (11) (11) (9) (11) Male n 7,076 n/a 5,859 n/a 2,488 n/a 2,910 n/a 18,333 n/a Mean (sd), interquartile range 72 (9) (11) (11) (9) (11) Age group by gender * n % n % n % n % n % Female < 45 years 116 1% 306 4% 96 2% % 744 3% years 283 2% % 296 7% % 1,959 7% years 1,768 13% 2,473 32% % % 5,905 22% years 5,094 37% 2,672 35% 1,483 36% 113 7% 9,362 35% years 5,359 39% 1,290 17% 1,038 25% 12 1% 7,699 28% > 85 years 1,023 8% 184 2% 212 5% 2 <1% 1,421 5% Male < 45 years 100 1% 326 6% 87 4% % 858 5% years 206 3% % 203 8% % 1,873 10% years 1,086 15% 1,905 33% % 1,342 46% 4,958 27% years 3,019 43% 2,178 37% % % 6,509 36% years 2,307 33% % % 19 1% 3,588 20% > 85 years 358 5% 97 2% 89 4% 3 <1% 547 3% * Age and gender reported for consenting patients only (82% of primary procedures) 4th Annual Report 75

76 Table 4.3 Characteristics of surgical practice for primary hip replacement procedures in 2006, according to type of procedure 2006 Patient procedure Total replacement using cement Total replacement not using cement Hybrid or reverse hybrid total replacement Primary resurfacing Total n % n % n % n % n % Total 25,313 n/a 16,416 n/a 8,027 n/a 5,596 n/a 55,352 n/a Laminar flow theatre ** Yes 21,238 98% 14,027 98% 6,976 98% 4,701 98% 46,942 98% No 478 2% 333 2% 169 2% 110 2% 1,090 2% Not recorded 3,597 n/a 2,056 n/a 882 n/a 785 n/a 7,320 n/a Patient position Lateral 21,097 83% 14,327 87% 7,607 95% 5,425 97% 48,456 88% Supine 4,216 17% 2,089 13% 420 5% 171 3% 6,896 12% Incision Anterior/Antero-lateral 4,392 17% 3,159 19% 1,022 13% 441 8% 9,014 16% Lateral (inc Hardinge) 11,592 46% 5,735 35% 2,519 31% % 20,740 37% Posterior 9,329 37% 7,522 46% 4,486 56% 4,261 76% 25,598 46% Trochanteric osteotomy Yes 1,140 5% 242 1% 87 1% 122 2% 1,591 3% No 24,173 95% 16,174 99% 7,940 99% 5,474 98% 53,761 97% Complex osteotomy Yes 259 1% 52 0% 9 0% 30 1% 350 1% No 25,054 99% 16, % 8, % 5,566 99% 55,002 99% Minimally invasive surgery ** Yes 924 4% 1,619 11% 386 5% 264 5% 3,193 6% No 22,015 96% 12,855 89% 7,088 95% 4,633 95% 46,591 94% Not recorded 2,374 n/a 1,942 n/a 553 n/a 699 n/a 5,568 n/a Incision length ** Greater than 10cm 19,050 89% 10,857 80% 6,323 89% 4,453 95% 40,683 87% Up to 10cm 2,308 11% 2,753 20% % 215 5% 6,018 13% Not recorded 3,955 n/a 2,806 n/a 962 n/a 928 n/a 8,651 n/a Image guided surgery ** Yes 94 0% 107 1% 31 0% 57 1% 289 1% No 22, % 13,955 99% 7, % 4,653 99% 48,114 99% Not recorded 2,957 n/a 2,354 n/a 752 n/a 886 n/a 6,949 n/a 76 National Joint Registry

77 Table 4.3 (continued) 2006 Patient procedure Total replacement using cement Total replacement not using cement Hybrid or reverse hybrid total replacement Primary resurfacing Total n % n % n % n % n % Total 25,313 n/a 16,416 n/a 8,027 n/a 5,596 n/a 55,352 n/a Femoral bonegraft used ** Yes 100 0% 141 1% 18 0% 33 1% 292 1% No 25, % 16,275 99% 8, % 5,563 99% 55,060 99% Acetabular bonegraft used ** Yes 644 3% 701 4% 479 6% 158 3% 1,982 4% No 24,669 97% 15,715 96% 7,548 94% 5,438 97% 53,370 96% Femoral cement used Yes 25, % 0 0% 7,646 95% 4,986 89% 37,945 69% No 0 0% 16, % 381 5% % 17,407 31% Acetabular cement used Yes 25, % 0 0% 385 5% 284 5% 25,982 47% No 0 0% 16, % 7,642 95% 5,312 95% 29,370 53% ** Optional field 4th Annual Report 77

78 Table 4.4 Thromboprophylaxis regime for primary hip replacement patients prescribed at time of operation, according to procedure 2006 Patient procedure Total replacement using cement Total replacement not using cement Hybrid or reverse hybrid total replacement Primary resurfacing Total Total 25,313 n/a 16,416 n/a 8,027 n/a 5,596 n/a 55,352 n/a n % n % n % n % n % Aspirin 6,085 24% 3,752 23% 2,447 30% 1,528 27% 13,812 25% Chloroquinine 11 0% 5 0% 0 0% 1 0% 17 0% Low dose heparin 266 1% 508 3% 182 2% 149 3% 1,105 2% Low molecular weight heparin 16,092 64% 9,831 60% 4,305 54% 2,716 49% 32,944 60% Pentasaccharide 161 1% 165 1% 58 1% 55 1% 439 1% Warfarin 458 2% 210 1% 164 2% 140 3% 972 2% Other chemical 393 2% 258 2% 109 1% 267 5% 1,027 2% Foot pump 6,595 26% 4,931 30% 2,420 30% 1,480 26% 15,426 28% Intermittent calf compression 6,315 25% 3,772 23% 1,915 24% 1,230 22% 13,232 24% TED stockings 14,712 58% 10,265 63% 5,094 63% 3,506 63% 33,577 61% Other mechanical 225 1% 133 1% 79 1% 35 1% 472 1% None recorded 98 0% 149 1% 18 0% 21 0% 286 1% Table 4.5 Reported untoward intra-operative events ** for primary hip replacement patients in 2006 according to procedure type 2006 Patient procedure Total replacement using cement Total replacement not using cement Hybrid or reverse hybrid total replacement Primary resurfacing Total Total 25,313 n/a 16,416 n/a 8,027 n/a 5,596 n/a 55,352 n/a n % n % n % n % n % None specified 25,067 99% 16,167 98% 7,952 99% 5, % 54,766 99% Total specified Calcar crack 46 17% % 21 25% 1 6% % Pelvic penetration 82 31% 16 6% 10 12% 1 6% % Shaft fracture 14 5% 17 7% 6 7% 0 0% 37 6% Shaft penetration 6 2% 5 2% 5 6% 1 6% 17 3% Trochanteric fracture 57 22% 44 17% 19 23% 0 0% % Other 60 23% 44 17% 23 27% 14 82% % NB: More than one event may be recorded for a patient ** Optional field 78 National Joint Registry

79 Table 4.6 Patient characteristics for hip revision procedures in 2006, according to procedure type 2006 Patient procedure Hip Single Stage Revision Hip Revision (Stage 1 of 2) Hip Girdlestone Total Total 4, ,355 Age, years (consenting patients only) n * 3, ,027 Mean (sd) 70 (12) 68 (12) 70 (15) 70 (12) Interquartile range n % n % n % n % Gender (consenting patients only) n * 3,765 n/a 234 n/a 34 n/a 4,033 n/a Female 2,187 58% % 19 56% 2,327 58% Male 1,578 42% % 15 44% 1,706 42% Patient physical status P1 Fit and healthy % 48 14% 2 3% % P2 Mild disease not incapacitating 2,928 59% % 31 53% 3,141 59% P3 Incapacitating systemic disease 1,207 24% % 23 39% 1,334 25% P4 Life threatening disease 66 1% 8 2% 3 5% 77 1% P5 Expected to die within 24hrs 10 0% 1 0% 0 0% 11 0% Indications for surgery ** Aseptic loosening 3,139 63% 76 22% 13 22% 3,228 60% Lysis 1,044 21% 52 15% 10 17% 1,106 21% Pain % 58 17% 16 27% 1,056 20% Dislocation/subluxation % 11 3% 11 19% % Periprosthetic fracture 397 8% 13 4% 4 7% 414 8% Infection 93 2% % 36 61% 407 8% Malalignment 325 7% 6 2% 0 0% 331 6% Fractured acetabulum 94 2% 3 1% 1 2% 98 2% Fractured stem 75 2% 5 1% 0 0% 80 1% Fractured femoral head 23 0% 0 0% 0 0% 23 0% Incorrect sizing/head socket mismatch 43 1% 3 1% 0 0% 46 1% Wear of acetabular component % 8 2% 1 2% % Dissociation of liner 60 1% 0 0% 0 0% 60 1% Other 281 6% 9 3% 4 7% 294 5% Side Bilateral 0 0% 0 0% 0 0% 0 0% Left, unilateral 2,484 50% % 24 41% 2,686 50% Right, unilateral 2,469 50% % 35 59% 2,669 50% * Age and gender reported for consenting patients only (75% of revision procedures) ** More than one indication may be recorded 4th Annual Report 79

80 Table 4.7 Indication for surgery for hip revision procedures in 2004 to 2006 Indications for Single Stage Revision hips Total 3,016 5,104 4,953 n % n % n % Aseptic loosening 1,994 66% 3,330 65% 3,139 63% Lysis % 1,120 22% 1,044 21% Pain % % % Infection 46 2% 84 2% 93 2% Indications for Two Stage Revision hips Total n % n % n % Aseptic loosening 90 44% 90 29% 76 22% Lysis 44 22% 57 18% 52 15% Pain 33 16% 42 13% 58 17% Infection % % % Table 4.8 Components removed during hip revision procedures in Patient procedure Hip Single Stage Revision Hip Revision (Stage 1 of 2) Hip Girdlestone Total Total 4, ,355 n % n % n % n % Both components (acetabular and femoral) 2,555 52% % 42 71% 2,889 54% Acetabular component +/- femoral head 1,252 25% 11 3% 3 5% 1,266 24% Femoral component alone % 29 8% 9 15% % Femoral head alone 155 3% 0 0% 0 0% 155 3% None 146 3% 11 3% 5 8% 162 3% 80 National Joint Registry

81 Table 4.9 Components used during single stage hip revision procedures in Hip Single Stage Revision Total 4,953 n % Femoral component cemented Yes 1,734 35% No 2,487 50% Not revised % Acetabular component cemented Yes 1,626 33% No 2,961 60% Not revised 366 7% ** Optional field Table 4.10 Types of hip re-operation other than revisions in Total 314 Type of re-operation * n % Socket augmentation 43 15% Wound exploration 43 15% Open reduction of dislocation 25 9% ORIF ** femur 17 6% Excision of heterotopic bone 7 2% ORIF ** trochanter 5 2% Focal bone graft only (femur) 4 1% Focal bone graft only (acetabulum) 1 0% Other procedure % * A procedure can have more than one type of re-operation recorded. There were 314 operations recorded for 283 procedures. ** ORIF = Open Reduction Internal Fixation 4th Annual Report 81

82 Table 4.11 Characteristics of patients undergoing hip re-operations other than revision 2006 Total 283 Age, years (consenting patients only) n * 168 Mean (sd) 71(12) Interquartile range n % Gender (consenting patients only) n* 168 n/a Female 97 58% Male 71 42% Patient physical status P1 Fit and healthy 32 11% P2 Mild disease, not incapacitating % P3 Incapacitating systemic disease 88 31% P4 Life threatening disease 3 1% P5 Expected to die within 24hrs 0 0% Side Bilateral 0 0% Left, unilateral % Right, unilateral % * Age and gender reported for consenting patients only (59% of re-operation procedures) 82 National Joint Registry

83 Table 4.12 Revision at 1 year for primary hip replacement procedures undertaken between 1 April 2003 and 30 September 2006 that were linked to a HES episode 20 Factor Category Number of patients Number revised within 1 year Crude revision rate 21 (95% CI) Hazard ratio (95% CI) 22 < 65 years 26, % (0.8% - 1.1%) 1.0 Age years 27, % (0.6% - 0.8%) 1.0 ( ) 75 + years 22, % (0.5% - 0.7%) 1.0 ( ) Gender Male 30, % (0.8% - 1.0%) 1.0 Female 45, % (0.5% - 0.7%) 0.8 ( ) Patient physical status P1 Fit and healthy 18, % (0.5% - 0.8%) 1.0 P2 Mild disease not incapacitating 46, % (0.7% - 0.8%) 1.6 ( ) P3+ Incapacitating systemic disease or worse 11, % (0.7% - 1.1%) 2.0 ( ) Total replacement using cement 41, % (0.3% - 0.4%) 1.0 Procedure type Total replacement not using cement 19, % (0.8% - 1.1%) 2.9 ( ) Hybrid total replacement 10, % (0.5% - 0.9%) 1.9 ( ) Hip resurfacing 6, % (1.3% - 2.0%) 5.0 ( ) NHS hospital 68, % (0.7% - 0.8%) 1.0 Provider type Independent hospital 2, % (0.2% - 0.7%) 0.6 ( ) NHS Treatment Centre 4, % (0.3% - 0.8%) 0.7 ( ) Independent Treatment Centre 1, % (0.1% - 0.9%) 0.5 ( ) 20 Procedures linked to a HES episode were those undertaken in England and mainly in NHS hospitals (see Section 2.2 of Part 2) 21 Calculated using the Kaplan-Meier survival analysis method 22 Relative hazard of revision within 1 year of primary hip replacement compared to a patient with a reference level of the factor (hazard ratio=1), adjusted for all other factors included in the analyses 4th Annual Report 83

84 Table 4.13 Causes of failure for primary hip replacement implants undertaken between 1 April 2003 and 30 September 2006 that were linked to a HES episode 23 and had a revision also linked to a HES episode THR using cement THR not using cement Primary hip procedure Hybrid THR Hip Resurfacing Total 151 n/a 191 n/a 72 n/a 82 n/a 496 n/a Cause of failure Periprosthetic fracture 9 6% 19 10% 10 14% 30 37% 68 14% Pain 11 7% 19 10% 15 11% 19 23% 60 12% Aseptic loosening 36 24% 41 21% 14 19% 16 20% % Infection 44 29% 25 13% 18 25% 6 7% 93 19% Malalignment 17 11% 31 16% 6 8% 4 5% 58 12% Dislocation/subluxation 32 21% 47 25% 16 22% 3 4% 98 20% Lysis 7 5% 7 4% 6 8% 1 4% 21 4% Fractured stem 3 2% 6 3% 1 1% 3 4% 13 3% Fractured acetabulum 1 <1% 0 0% 1 1% 1 1% 98 2% Fractured femoral head 1 <1% 6 3% 0 0% 1 1% 8 2% Incorrect sizing/head socket mismatch 1 <1% 3 2% 1 1% 1 1% 6 1% Wear of acetabular component 0 0% 3 2% 1 1% 0 0% 4 1% Dissociation of liner 0 0% 3 2% 0 0% 0 0% 3 1% Other 7 5% 11 6% 2 3% 15 18% 35 7% Total 23 Procedures linked to a HES episode were those undertaken in England and mainly in NHS hospitals (see Section 2.2 of Part 2) Table 4.14 Mortality rates and age-and-gender-standardised mortality ratios at 1 year following primary hip replacement for procedures linked to a HES episode 24, Procedure type Number of procedures Deaths Rate 25 (95% CI) SMR (95% CI) Total 45, % (1.8% - 2.0%) 0.46 ( ) Cemented THR 25, % (2.2% - 2.5%) 0.46 ( ) Cementless THR 10, % (1.4% - 1.8%) 0.49 ( ) Hybrid THR 6, % (1.3% - 1.9%) 0.42 ( ) Hip resurfacing 3, % (0.3% - 0.6%) 0.39 ( ) 24 Procedures linked to a HES episode were those undertaken in England and mainly in NHS hospitals (see Section 2.2 of Part 2) 25 Calculated using the Kaplan-Meier survival analysis method 84 National Joint Registry

85 Table 4.15 Mortality at 1 year for primary hip replacement procedures undertaken between 1 April 2003 and 30 June 2006 that were linked to a HES episode 26 Factor Category Number of patients Number dying within 1 year Hazard ratio 27 (95% CI) < 65 years 25, Age years 27, ( ) 75+ years 22, ( ) Gender Male 30, Female 45, ( ) Patient physical status P1 Fit and healthy 18, P2 Mild disease not incapacitating 45, ( ) P3+ Incapacitating systemic disease or worse 11, ( ) Total replacement using cement 41, Procedure type Total replacement not using cement 18, ( ) Hybrid total replacement 10, ( ) Hip resurfacing 5, ( ) NHS hospital 68,239 1, Provider type Independent hospital 2, ( ) NHS Treatment Centre 4, ( ) Independent Treatment Centre 1, ( ) 26 Procedures linked to a HES episode were those undertaken in England and mainly in NHS hospitals (see Section 2.2 of Part 2) 27 Relative hazard of death within 1 year of primary hip replacement compared to a patient with a reference level of the factor (hazard ratio=1), adjusted for all other factors included in the analyses 4th Annual Report 85

86 Table 4.16 Length of hospital stay following admission for a primary hip replacement for procedures linked to a HES episode 28, Factor Category Number of patients Average length of stay (days) (95% CI) Adjusted difference in average LOS* (days) (95% CI) <45 years 2, ( ) years 6, ( ) -0.3 (-0.7 _ 0.1) Age years 18, ( ) -0.2 (-0.5 _ 0.1) years 28, ( ) 0.5 (0.2 _ 0.9) years 20, ( ) 2.8 (2.4 _ 3.2) 85+ years 3, ( ) 6.4 (6.0 _ 6.8) Gender Male 32, ( ) 0.0 Female 47, ( ) 0.6 (0.4 _ 0.7) Patient physical status P1 - Fit and healthy 19, ( ) 0.0 P2 - Mild disease not incapacitating 48, ( ) 0.6 (0.5 _ 0.8) P3 - Incapacitating systemic disease 11, ( ) 3.5 (3.3 _ 3.7) P4 - Life threatening disease ( ) 6.7 (6.0 _ 7.4) Total replacement using cement 43, ( ) 0.0 Procedure type Total replacement not using cement 20, ( ) 0.02 (-0.1_ 0.2) Hybrid total replacement 10, ( ) 0.2 (0.03 _ 0.4) Hip resurfacing 6, ( ) -1.0 (-1.2 _ -0.7) NHS hospital 71, ( ) 0.0 Provider type Independent hospital 3, ( ) -2.5 (-2.9 _ -2.2) NHS Treatment Centre 4, ( ) -3.5 (-4.0 _ -3.0) Independent Treatment Centre 1, ( ) -2.6 (-2.8 _ -2.3) * Difference in average length of stay compared to reference level (average difference=0 days) after adjusting for other factors 28 Procedures linked to a HES episode were those undertaken in England and mainly in NHS hospital (see Section 2.2 of Part 2) 86 National Joint Registry

87 Table 4.17 Length of hospital stay following admission for a primary hip procedure according to age and gender for procedures linked to a HES episode 29, Patient characteristics Female < 55 years Female > 55 years Male < 55 years Male > 55 years Total Total 4, , , , , Procedure type n Mean (days) Interquartile range (days) n Mean (days) Interquartile range (days) n Mean (days) Interquartile range (days) n Mean (days) Interquartile range (days) n Mean (days) Interquartile range (days) THR using cement THR not using cement Hybrid or reverse hybrid THR Hip resurfacing , , , , , , , , , , , , , , , , Procedures linked to a HES episode were those undertaken in England and mainly in NHS hospital (see Section 2.2 of Part 2) 4th Annual Report 87

88 Part 2 5. Knee Replacement Procedures 88 National Joint Registry

89 5.1 Knee Replacement Procedures, 2006 This section summarises the patient characteristics of all 57,597 primary, 3,048 revision and 341 re-operation knee replacement procedures undertaken between 1 January 2006 and 31 December 2006 and entered into the NJR by 28 February Fields for which data entry is optional are indicated in the tables of results. All optional fields, apart from untoward intra-operative events, were reported in more than 80% of procedures Primary knee replacement procedures, 2006 Over 80% of the 57,597 primary knee replacement procedures undertaken in 2006 were cemented total knee replacement (TKR) procedures and 4,533 (8%) were unicondylar knee replacements (Table 5.1). Compared with previous years the types of primary knee replacement procedures undertaken have largely remained the same Patient characteristics The average age was 70 years and 57% of the patients were female. Patients undergoing a patello-femoral replacement were the youngest, at an average age of 61 years, with three-quarters of these being female. On average, female patients were one year older than male patients at the time of their primary knee replacement (70 years and 69 years, respectively, Table 5.2). According to the American Society of Anaesthesiologists (ASA) grade system,18% of the patients undergoing a primary knee replacement procedure were graded as fit and healthy (Table 5.1). The single largest indication recorded for surgery was osteoarthritis, recorded in 97% of all primary procedures. Compared with previous years, the patient characteristics described above have largely remained unchanged. However, there has been an increase in patients with mild or incapacitating disease prior to surgery. For example, patients with mild disease increased from 62% in 2004 to 68% in A similar trend in the recorded ASA grade of patients was seen in primary hip replacement procedures Surgical techniques The most common surgical approach was the medial parapatellar, used in over 90% of procedures (Table 5.3). Where recorded minimally invasive surgery (MIS) was used in over half of unicondylar knee replacement procedures, compared with use in 3% of all other types of knee replacement procedures. Compared with previous years, the surgical techniques used in primary knee replacements have largely remained unchanged. There was, however, an increase in the use of MIS in unicondylar knee replacements from 37% in 2004 to 56% in Thromboprophylaxis The most frequently prescribed chemical method was low molecular weight heparin, and TED stockings were the most frequently prescribed mechanical method (Table 5.4). Compared with previous years, there has been an increase in the prescription of a combined chemical and mechanical regime from 49% in 2004 to 60% in The increase can be attributed to similar changes in the prescription of low molecular weight heparin, which increased from 49% in 2004 to 57% in 2006, and TED stockings which increased from 55% in 2004 to 62% in A marginal increase was also seen in the prescription of a foot pump from 24% in 2004 to 28% in A similar trend in the prescribed thromboprophylaxis regime was found in primary hip replacement procedures Untoward intra-operative events Table 5.5 shows that untoward intra-operative events were rare, reported in 0.5% of procedures. Completion of the data field requesting these events was not mandatory and the default option, which held when the field was not completed, was that no untoward intra-operative event occurred. Of the 265 untoward events reported, over a third were fractures. Compared with previous years, the frequency and pattern of untoward intra-operative events has largely remained the same Knee revisions, 2006 A total of 3,048 knee revision procedures were reported. This includes 431 (14%) procedures that were Stage 2 of a two-stage revision procedure that have been excluded from the rest of the section. Of the remaining 2,617 procedures, 2,242 (86%) were single stage revision operations and 359 (14%) were Stage 1 of a two-stage process (Table 5.6). A further 16 (<1%) procedures were recorded, comprising 13 conversions of previous knee replacements to arthrodesis and 3 knee amputations. Compared with previous years, there has been no change in the types of revision procedures carried out Patient characteristics The mean age of knee revision patients was 70 years (Table 5.6). There were more female (52%) than male patients (48%). Aseptic loosening was the most common indication for single stage revision and infection was the most common indication for two-stage revision. Compared with previous years, the patient characteristics described above have largely remained the same. However, there was an increase in patients with mild or incapacitating disease. For example, procedures in patients with mild disease increased from 59% in 2004 to 64% in Components removed In three-quarters of the revision procedures, the femoral and tibial components were both removed (Table 5.7). 4th Annual Report 89

90 Figure 5.1 Revision rate estimates for HES-linked primary knee replacement procedures, Analysis time (years from operation) Revision rate (95% Cl) Procedure type (n) 1 year 1 year Cemented TKR Cemented (68,904) Cementless (5,904) Unicondylar (4,110) 0.3% (0.3% - 0.4%) 0.3% (0.2% - 0.6%) 0.5% (0.3% - 0.8%) 1.3% (1.2% - 1.5%) 1.5% (1.0% - 2.0%) 2.4% (1.4% - 4.1%) Unicondylar Cementless TKR Knee re-operations other than revision, 2006 A total of 341 knee re-operation procedures undertaken after an initial knee replacement were recorded. Of all re-operations, 178 (52%) involved resurfacing of the patella and 44 (13%) were reported as manipulation under anaesthesia (Table 5.8). 29% of the re-operations had other descriptions outside of the list of options given and included exchange of the tibial insert. The characteristics of patients undergoing a knee re-operation in 2006 are shown in Table 5.9. The average age of the patients was 69 years and half of these were female. 5.2 Outcomes Following Primary Knee Replacement, This section presents analyses of revision, mortality rates and length of stay for primary knee replacement procedures. Particular emphasis is also given to revision of unicondylar knee replacements. The analyses are based on procedures undertaken between 1 April 2003 and 30 September 2006 that were linked to an episode in the HES database. As explained in Section 2.2, the linked procedures were those undertaken in England, and mainly in NHS hospitals. A description of the linkage process, as well as the patient characteristics of the linked procedures is also included in Section Revision All 80,696 primary knee replacement procedures in the NJR that were undertaken between 1 April 2003 and 30 September 2006 and linked to a HES episode that was also defined as a primary knee replacement procedure were identified. Of the linked primary knee replacement procedures, 75,944 (94%) were undertaken at NHS hospitals and NHS treatment centres and 4,752 (6%) were undertaken in the independent sector. In HES, primary knee replacements for the patients with linked procedures were identified using the following OPCS-4 procedure codes: W401 Primary total prosthetic replacement of knee joint using cement. W411 Primary total prosthetic replacement of knee joint not using cement. W421 Primary total prosthetic replacement of knee joint not elsewhere classified (nec). W581 Primary resurfacing arthroplasty of joint (used only if procedure code Z846 (knee joint) is also specified). W521 Primary prosthetic replacement of articulation of bone using cement nec. 90 National Joint Registry

91 Kaplan-Meier survival estimate Age <65 years Age 65+ years Figure 5.2 Revision rate estimates by age for HES-linked primary knee replacement procedures, Cemented TKR Analysis time (years from operation) Analysis time (years from operation) Cementless TKR Unicondylar 1 year revision rates (95% Cl) [n=18,189] 1 year revision rates (95% Cl) [n=58,335] Cemented TKR Cementless TKR Unicondylar 0.5% (0.4% - 0.6%) 0.5% (0.2% - 1.1%) 0.8% (0.4% - 1.4%) Cemented TKR Cementless TKR Unicondylar 0.3% (0.3% - 0.4%) 0.3% (0.2% - 0.6%) 0.4% (0.2% - 0.8%) Some patients had two primary knee replacement procedures, one on each side, which occurred on different dates and were both linked to a HES record. In such cases, to avoid including a patient twice in the linked database, only the earliest primary procedure was retained. For each linked patient, all hospital episodes recorded in HES that succeeded the primary procedure were identified. From these succeeding episodes, the first knee revision that occurred on the same side as the primary procedure was then identified in HES. Where the side of the primary or the revision was not given, the first revision that occurred after the primary procedure was assumed to be a revision of that primary. In HES, revision procedures were identified using the procedure codes W403, W413, W423, W582 (only with Z846) and W523 indicating revision of a cemented, cementless, unclassified, knee resurfacing, and replacement of articulation of bone primary procedure, respectively. In addition, revision codes indicating conversion from one type of replacement to another, as well as attention to the replacement joint in which there was renewal of the prosthesis, were also identified as revisions. Codes indicating other types of attention to the hip replacement joint, such as correction of displacement of prosthesis, were considered to be re-operations and were not included as revisions. Using the revisions identified in HES as described above, revision rates were then estimated for various patient characteristics, as well as procedure and provider types. The number of linked hybrid total knee replacements and patello-femoral replacements was too low to allow reliable estimates of revision rates to be obtained and these procedures are therefore excluded from the results presented below. Revision rates were estimated using the Kaplan-Meier survival analysis method that allows prostheses that are followed up for unequal lengths of time after implant to be included Procedure type The overall revision rate for primary knee replacement was 0.4% (95% CI 0.3% to 0.4%) at 1 year and 1.4% (95%CI: 1.2% to 1.6%) at 3 years. Figure 5.1 shows estimates of implant survival to revision by procedure type, together with revision rates within 1 year and 3 years following primary knee replacement Age and gender Figure 5.2 shows revision rates by procedure type for patients aged less than 65 years and those aged 65 and over, separately. Revision rates in older patients were lower than those in younger patients. 4th Annual Report 91

92 Kaplan-Meier survival estimate Female Male Figure 5.3 Survival to revision and revision rates for male and female patients with HES-linked primary knee replacement procedures, Cemented TKR Analysis time (years from operation) 1 year revision rates (95% Cl) [n=45,467] Analysis time (years from operation) 1 year revision rates (95% Cl) [n=33,415] Cementless TKR Unicondylar replacement Cemented TKR 0.3% (0.3% - 0.4%) Cemented TKR 0.4% (0.3% - 0.5%) Cementless TKR 0.2% (0.1% - 0.5%) Cementless TKR 0.6% (0.3% - 1.0%) Unicondylar 0.3% (0.1% - 0.7%) Unicondylar 0.8% (0.4% - 1.3%) Figure 5.3 shows revision rates for female and male patients separately. Revision rates were lower in female patients than in male patients, but the differences were not statistically significant. 92 National Joint Registry

93 Figure 5.4 Revision rate estimates for the five most commonly used brands of total condylar knee prostheses, Analysis time (years from operation) Revision rate (95% Cl) Brand (n) 1 year 3 years AGC AGC (10,203) 0.3% (0.2% - 0.5%) 1.2% (0.9% - 1.6%) Kinemax Kinemax (5,091) Nexgen (9,857) PFC Sigma (26,833) Scorpio (5,386) 0.3% (0.3% - 0.7%) 0.2% (0.1% - 0.3%) 0.4% (0.3% - 0.5%) 0.3% (0.2% - 0.5%) 1.6% (1.2% - 2.2%) 0.8% (0.5% - 1.2%) 1.3% (1.1% - 1.6%) 1.6% (1.0% - 2.5%) Nexgen PFC Sigma Scorpio Table 5.10 shows the results of a multivariable analysis in which the impact of patient age, gender and physical status, as well as procedure and provider type on 1-year revision rates is explored (see Section for an explanation of multivariable analyses and hazard ratios). There was no significant difference in revision rates across the different procedure types after adjusting for age, gender, physical status and provider type Revision rates for most frequently used implant brands Figure 5.4 shows revision rates for the five most commonly used brands of total condylar knee replacement prostheses. There were no statistically significant differences in 1 and 3-year revision rates among the different brands Comparison of revision rates with other registries A comparison of revision rates in the NJR with those reported in other national registries showed that the rates reported in the NJR were generally lower than those reported elsewhere 30,31,32. However, there were differences in the definition of what a revision is across registries, with some registries including re-operations with revisions. Furthermore, revisions were specified for different time periods and it has been shown that revision rates have improved significantly over time. 30 Australian Orthopaedic Association National Joint Replacement Registry Annual Report documents/aoanjrrreport_2006.pdf 31 The Norwegian Arthroplasty Register, Swedish Knee Arthroplasty Register Annual Report th Annual Report 93

94 Figure 5.5 Revision rate estimates for the five most commonly used brands of total condylar knee prostheses, Analysis time (years from operation) Revision rate (95% Cl) Brand (n) Oxford III (2,664) 1 year 0.6% (0.3% - 1.1%) 3 years 2.6% (1.3% - 5.3%) Unicondylar knee replacement procedures This section presents results of detailed analyses of unicondylar knee procedures, focusing on revision rates for the most commonly used brand of prostheses, causes of failure compared to other types of primary knee replacement as well as revision rates of procedures where minimally invasive surgery was used. Figure 5.5 shows revision rates for the Oxford III unicondylar knee prostheses, which is the most frequently used brand. There were insufficient procedures performed to allow reliable estimates of revision rates to be obtained for other brands of unicondylar knee prostheses Causes of failure Table 5.11 shows causes of failure for different primary knee replacement procedure types. The most common causes of failure for unicondylar knee procedures were aseptic loosening and pain. In comparison, the most common cause of failure for cemented TKR procedures was infection Use of minimally invasive surgery Recent trends show an increase in the use of minimally invasive surgery (MIS) in unicondylar knee replacement (Section ). Figure 5.6 shows revision rates for unicondylar knee replacement procedures in which MIS was used and those in which conventional methods were used. There were no statistically significant differences in 1 year revision rates following unicondylar knee replacement between procedures in which MIS was used and procedures in which conventional methods were used. 94 National Joint Registry

95 Figure 5.6 Revision rates comparing use and non-use of minimally invasive surgery in unicondylar knee procedures, Analysis time (years from operation) MIS use (n) Revision rate (95% Cl) 1 year Minimally invasive surgery used Minimally invasive surgery not used MIS used (1,581) MIS not used (2,142) 0.2% (0.1% - 0.9%) 0.8% (0.4% - 1.6%) Mortality This section summarises mortality rates for primary knee replacement patients for procedures undertaken between 1 April 2003 and 30 June 2006 that were linked to a HES record. At the time of analyses, dates of death were only available up to 30 June 2006 and only those procedures undertaken up to this date could therefore be analysed. The mortality rate of primary knee replacement patients was 1.6% (95% CI 1.5% - 1.7%) at 1 year and 5.1% (95% CI 4.7% - 5.5%) at 3 years. Mortality rates at 1 year following primary knee replacement were compared with those of the general population of England and Wales using age and sex adjusted standardised mortality ratios (Table 5.12). The comparison showed that mortality among knee replacement patients is about a third of that observed in the general age and sex-matched population, with the overall SMR being 0.35 (95% CI ). Table 5.13 shows mortality rates at 1 year following a primary knee replacement by patient age, sex and physical status as well as procedure and provider type, together with results of a multivariable analysis (see Section for an explanation of multivariable analyses and hazard ratios). After adjusting for confounding factors, mortality within 1 year remains higher for older patients and those in a poor general medical condition, but lower for female than male patients. Mortality at 1 year following unicondylar knee replacement is lower than that following cemented total knee replacement after adjusting for age, sex and patient physical status. However, interpretation of the results is complicated by the differences in patient characteristics across the procedure types Thromboprophylaxis Mortality rates up to 1 year following primary knee replacement were compared between patients with different types of thromboprophylaxis prescribed at the time of surgery, including those for whom none was prescribed. There were no statistically significant differences in mortality between the different types prescribed (Figure 5.7). 4th Annual Report 95

96 Figure 5.7 Mortality for patients with and those without any thromboprophylaxis prescribed at the time of primary knee replacement, Analysis time (years from operation) Mortality rate (95% Cl) 3 months 6 months 1 year None prescribed None prescribed [n=1,376] Chemical only [n=19,033] 0.5% (0.3% - 1.1%) 0.6% (0.5% - 0.7%) 0.9% (0.5% - 1.6%) 0.9% (0.8% - 1.1%) 2.0% (1.4% - 2.9%) 1.6% (1.4% - 1.8%) Chemical only Mechanical only Both types Mechanical only [n=14,150] 0.5% (0.4% - 0.6%) 0.8% (0.6% - 0.9%) 1.5% (1.3% - 1.8%) Both types [n=43,399] 0.5% (0.5% - 0.6%) 0.9% (0.8% - 1.0%) 1.6% (1.5% - 1.8%) Length of stay This section presents results for the analysis of length of hospital stay following admission for primary knee replacement procedures linked to a HES episode. Table 5.14 gives the average length of stay for several patient characteristics, as well as procedure and provider type. The average length of stay was calculated as the total number of bed days divided by the number of patients. TKR procedure a difference of about 2 days. The difference in the average length of stay between the two procedure types remained the same after adjusting for the other factors (shown in Table 5.14). The average length of stay following primary knee replacement was 8.1 days. The length of stay is influenced by several factors, including those shown in Table Patients who undergo unicondylar knee replacement procedures are on average younger than those who undergo total knee replacement, and this difference in average age should be taken into account in comparing the length of stay across different procedure types. The difference in average length of stay shown for each factor in Table 5.14 is adjusted for the other factors in the table. Patients stayed on average, 5.9 days following a primary unicondylar knee replacement compared with an average of 8.3 days following a cemented 96 National Joint Registry

97 5 Knee Replacement Procedures Table 5.1 Patient characteristics for primary knee replacement procedures in 2006, according to type of procedure 2006 Patient procedure Total replacement using cement Total replacement not using cement Hybrid Unicondylar knee replacement Patello-femoral replacement Total 47,626 4, , ,597 Age, years (consenting patients only) n * 38,908 n/a 3,194 n/a 591 n/a 3,754 n/a 495 n/a 46,942 n/a Mean (sd) 71 (9) n/a 69 (10) n/a 69 (10) n/a 65 (10) n/a 61 (12) n/a 70 (10) n/a Interquartile range n/a n/a n/a n/a n/a n/a n % n % n % n % n % n % Gender (consenting patients only) n * 38,995 n/a 3,202 n/a 591 n/a 3,766 n/a 495 n/a 47,049 n/a Male 16,422 42% 1,511 47% % 1,894 50% % 20,215 43% Female 22,573 58% 1,691 53% % 1,872 50% % 26,834 57% Patient physical status P1 Fit and healthy 7,646 16% % % 1,263 28% % 10,086 18% Total P2 Mild disease not incapacitating P3 Incapacitating systemic disease P4 Life threatening disease P5 Expected to die within 24hrs 32,671 69% 2,663 65% % 2,918 64% % 39,108 68% 7,057 15% % 86 12% 341 8% 44 7% 8,117 14% 218 0% 17 0% 2 0% 10 0% 2 0% 249 0% 34 0% 2 0% 0 0% 1 0% 0 0% 37 0% Indications for surgery ** Osteoarthritis 46,074 97% 3,978 97% % 4,496 99% % 55,850 97% Avascular necrosis 207 0% 6 0% 6 1% 39 1% 1 0% 259 0% Other inflammatory arthopathy 278 1% 18 0% 7 1% 2 0% 1 0% 306 1% Infection 34 0% 4 0% 2 0% 2 0% 0 0% 42 0% Rheumatoid arthritis 1,098 2% 85 2% 11 2% 3 0% 3 0% 1,200 2% Trauma 271 1% 28 1% 10 1% 8 0% 5 1% 322 1% Other 440 1% 48 1% 12 2% 20 0% 20 3% 540 1% Side Bilateral 359 1% 66 2% 14 2% 135 3% 36 6% 610 1% Left, unilateral 22,399 47% 1,899 46% % 2,207 49% % 27,094 47% Right, unilateral 24,868 52% 2,123 52% % 2,191 48% % 29,893 52% * Age and gender reported for consenting patients only (82% of primary procedures) ** More than one indication may be recorded 4th Annual Report 97

98 Table 5.2 Age and gender for primary knee replacements in Patient procedure Total replacement using cement Total replacement not using cement Hybrid total replacement Unicondylar knee replacement Patello-femoral replacement Overall Average age by gender * Female n 22,526 n/a 1,686 n/a 325 n/a 1,870 n/a 373 n/a 26,780 n/a Mean (sd), Interquartile range 71 (9) (10) (10) (10) (11) (10) Male n 16,377 n/a 1,508 n/a 266 n/a 1,883 n/a 122 n/a 20,156 n/a Mean(sd), Interquartile range 70 (9) (9) (11) (9) (13) (9) Age group by gender * n % n % n % n % n % n % Female < 45 years 136 1% 24 1% 1 0% 29 2% 28 8% 218 1% years 975 4% 108 6% 23 7% % 98 26% 1,495 6% years 4,672 21% % 96 30% % % 5,997 22% years 8,470 38% % % % 86 23% 9,807 37% years 7,166 32% % 88 27% % 31 8% 8,039 30% > 85 years 1,107 5% 62 4% 17 5% 30 2% 8 2% 1,224 5% Male < 45 years 125 1% 8 1% 9 3% 30 2% 14 11% 186 1% years 704 4% 86 6% 25 9% % 26 21% 1,062 5% years 3,951 24% % 67 25% % 27 22% 5,206 26% years 6,461 39% % 92 35% % 33 27% 7,781 39% years 4,572 28% % 65 24% % 18 15% 5,279 26% > 85 years 564 3% 40 3% 8 3% 26 1% 4 3% 642 3% * Age and gender reported for consenting patients only (82% of primary procedures) 98 National Joint Registry

99 Table 5.3 Characteristics of surgical practice for primary knee replacement procedures in 2006, according to type of procedure 2006 Patient procedure Total replacement using cement Total replacement not using cement Hybrid Unicondylar knee replacement Patello-femoral replacement Total Total 47,626 4, , ,597 n % n % n % n % n % n % Laminar flow theatre ** Yes 40,382 98% 3,241 97% % 3,853 97% % 48,602 98% No 854 2% 108 3% 45 7% 104 3% 16 3% 1,127 2% Not recorded 6,390 n/a 739 n/a 74 n/a 576 n/a 89 n/a 7,868 n/a Surgical approach Lateral parapatellar 646 1% 67 2% 9 1% 141 3% 42 6% 905 2% Medial parapatellar 44,032 92% 3,775 92% % 4,131 91% % 53,081 92% Sub-vastus 736 2% 83 2% 80 11% 48 1% 11 2% 958 2% Other 2,212 5% 163 4% 12 2% 213 5% 53 8% 2,653 5% Minimally invasive surgery ** Yes 1,178 3% 116 3% 8 1% 2,216 56% 48 9% 3,566 7% No 41,412 97% 3,384 97% % 1,745 44% % 47,658 93% Not recorded 5,036 n/a 588 n/a 56 n/a 572 n/a 121 n/a 6,373 n/a Image guided surgery ** Yes 771 2% 166 5% 7 1% 103 3% 8 2% 1,055 2% No 41,724 98% 3,335 95% % 3,834 97% % 50,053 98% Not recorded 5,131 n/a 587 n/a 51 n/a 596 n/a 124 n/a 6,489 n/a Femoral bonegraft used ** Yes 136 0% 27 1% 6 1% 1 0% 0 0% 170 0% No 47, % 4,061 99% % 4, % % 57, % Tibial bonegraft used ** Yes 139 0% 33 1% 5 1% 3 0% 0 0% 180 0% No 47, % 4,055 99% % 4, % % 57, % Femoral cement used Yes 47, % 8 0% % 4,427 98% % 52,787 92% No 1 0% 4, % % 106 2% 65 10% 4,810 8% Tibial cement used Yes 47, % 9 0% % 4,424 98% 0 0% 52,629 91% No 2 0% 4, % % 109 2% % 4,968 9% Patella cement used Yes 20,157 46% 180 5% % % % 21,606 42% No 23,216 54% 3,183 95% % 2,607 90% 76 13% 29,516 58% Not recorded 6,248 n/a 628 n/a 42 n/a 986 n/a 11 n/a 7,915 n/a ** Optional field 4th Annual Report 99

100 Table 5.4 Thromboprophylaxis regime for primary knee replacement patients prescribed at time of operation, according to procedure 2006 Patient procedure Total replacement using cement Total replacement not using cement Hybrid Unicondylar knee replacement Patello-femoral replacement Total Total 47,626 4, , ,597 n % n % n % n % n % n % Aspirin 12,419 26% 1,013 25% % 1,173 26% % 14,886 26% Chloroquinine 25 0% 4 0% 0 0% 2 0% 0 0% 31 0% Low dose heparin 906 2% 93 2% 6 1% 46 1% 6 1% 1,057 2% Low molecular weight heparin 27,739 58% 2,240 55% % 2,306 51% % 32,924 57% Pentasaccharide 281 1% 2 0% 1 0% 42 1% 4 1% 330 1% Warfarin 578 1% 44 1% 9 1% 33 1% 8 1% 672 1% Other chemical 495 1% 21 1% 6 1% 28 1% 9 1% 559 1% Foot pump 13,118 28% 1,594 39% % 1,083 24% % 16,319 28% Intermittent calf compression 11,149 23% 1,285 31% % 1,272 28% % 14,031 24% TED stockings 29,044 61% 2,881 70% % 2,800 62% % 35,649 62% Other mechanical 473 1% 18 0% 6 1% 28 1% 13 2% 538 1% None 586 1% 21 1% 2 0% 34 1% 9 1% 652 1% Table 5.5 Reported untoward intra-operative events ** for primary knee replacement patients in 2006 according to procedure type 2006 Patient procedure Total replacement using cement Total replacement not using cement Hybrid Unicondylar knee replacement Patello-femoral replacement Total Total 47,626 4, , ,597 n % n % n % n % n % n % None specified 47, % 4, % % 4, % % 57, % Total specified 227 n/a 14 n/a 6 n/a 15 n/a 3 n/a 265 n/a Fracture % % % % 0 0.0% % Patella tendon avulsion % 1 7.1% % 0 0.0% 0 0.0% % Ligament injury % 0 0.0% 0 0.0% 1 6.7% 0 0.0% % Other % % % % % % NB: More than one event may be recorded for a patient ** Optional field 100 National Joint Registry

101 Table 5.6 Patient characteristics for knee revision procedures in 2006, according to procedure type 2006 Patient procedure Knee Single Stage Revision Knee Revision (Stage 1 of 2) Knee conversion to arthrodesis Knee amputation Total Total 2, ,617 Age, years (consenting patients only) n * 1, ,002 Mean (sd) 70 (10) 70 (10) 78 (6) (10) Interquartile range n/a n % n % n % n % n % Gender (consenting patients only) n * 1,742 n/a 259 n/a 8 n/a 1 n/a 2,010 n/a Male % % 4 50% 0 n/a % Female % % 4 50% 1 n/a 1,047 52% Patient physical status P1 Fit and healthy % 41 11% 1 8% 0 0% % P2 Mild disease, not incapacitating P3 Incapacitating systemic disease 1,446 64% % 5 38% 0 0% 1,668 64% % 98 27% 6 46% 3 100% % P4 Life threatening disease 25 1% 3 1% 1 8% 0 0% 29 1% P5 Not expected to survive 24 hours 0 0% 0 0% 0 0% 0 0% 0 0% Indications for surgery ** Aseptic loosening 1,020 45% 43 12% 2 15% 0 0% 1,065 41% Pain % 27 8% 1 8% 0 0% % Lysis % 56 16% 1 8% 0 0% % Wear of polyethylene component % 13 4% 0 0% 0 0% % Instability % 20 6% 2 15% 0 0% % Infection 74 3% % 8 62% 1 33% % Malalignment % 9 3% 0 0% 0 0% 223 9% Dislocation/subluxation 151 7% 5 1% 0 0% 0 0% 156 6% Periprosthetic fracture 91 4% 6 2% 0 0% 0 0% 97 4% Stiffness 123 5% 12 3% 3 23% 1 33% 139 5% Implant fracture 43 2% 2 1% 0 0% 0 0% 45 2% Component dissociation 56 2% 4 1% 0 0% 0 0% 60 2% Other 191 9% 13 4% 2 15% 1 33% 207 8% Side Bilateral 2 <1% 0 0% 0 0% 0 0% 2 <1% Left, unilateral 1,076 48% % 6 4% 1 33% 1,263 48% Right, unilateral 1,164 51% % 7 54% 2 67% 1,352 52% * Age and gender reported for consenting patients only (77% of revision procedures) ** More than one indication may be recorded 4th Annual Report 101

102 Table 5.7 Combinations of implants removed during Single and 2-Stage Knee Revision procedures in Patient procedure Knee Single Stage Revision Knee Revision (Stage 1 of 2) Total Total 2, ,601 n % n % n % Femoral component and not tibial component 185 8% 6 2% 191 7% Tibial component and not femoral component 146 7% 3 1% 149 6% Femoral component + tibial component 1,656 74% % 1,986 76% Other combination (not femoral or tibial component) % 20 6% % Table 5.8 Types of knee re-operations entered into the NJR database 2006 Total 380 Type of re-operation * n % Resurfacing of patella % Manipulation under anaesthesia 44 13% Washout 18 5% Wound debridement 21 6% Soft tissue repair/realignment 12 4% ORIF ** peri-prosthetic fracture 7 2% Other procedure % * A procedure can have more than one type of re-operation recorded. There were 380 re-operations recorded for 341 procedures ** ORIF = Open Reduction Internal Fixation 102 National Joint Registry

103 Table 5.9 Characteristics of patients undergoing knee re-operations other than revision 2006 Total 341 Age, years (consenting patients only) n Mean (sd) Interquartile range Gender (consenting patients only) n Male Female Patient physical status P1 Fit and healthy P2 Mild disease, not incapacitating P3 Incapacitating systemic disease P4 Life threatening disease P5 Not expected to survive 24 hours Side Bilateral Left, unilateral Right, unilateral (11) n % 50% 50% 14% 63% 22% 1% <1% 1% 44% 55% * Age and gender reported for consenting patients only (69% of re-operation procedures) 4th Annual Report 103

104 Table 5.10 Revision at 1 year for primary knee replacement procedures undertaken between 1 April 2003 and 30 September 2006 that were linked to a HES episode 33 Factor Category Number of patients Number revised within 1 year Crude revision rate 34 (95% CI) Hazard ratio 35 (95% CI) Age < 65 years 20, % (0.4% - 0.6%) years 30, % (0.3% - 0.4%) 0.8 ( ) 75+ years 27, % (0.2% - 0.4%) 0.7 ( ) Gender Male 33, % (0.4% - 0.5%) 1.0 Female 45, % (0.3% - 0.4%) 0.7 ( ) Patient physical status P1 Fit and healthy P2 Mild disease not incapacitating P3+ Incapacitating systemic disease or worse 14,965 51,141 12, % (0.3% - 0.5%) 0.3% (0.3% - 0.4%) 0.4% (0.3% - 0.6%) ( ) 1.2 ( ) Procedure type Total replacement using cement Total replacement not using cement 68,904 5, % (0.3% - 0.4%) 0.4% (0.2% - 0.6%) ( ) Unicondylar replacement 4, % (0.3% - 0.8%) 1.3 ( ) Provider NHS hospital 69, % (0.3% - 0.4%) 1.0 type Independent hospital 3, % (0.2% - 0.7%) 1.0 ( ) NHS Treatment Centre 4, % (0.1% - 0.5%) 0.7 ( ) Independent Treatment Centre 1, % ( ) - 33 Procedures linked to a HES episode were those undertaken in England and mainly in NHS hospital (see Section 2.2 of Part 2) 34 Calculated using the Kaplan-Meier survival analysis method 35 Relative hazard of revision within 1 year of primary knee replacement compared to a patient with a reference level of the factor (hazard ratio=1), adjusted for all other factors included in the analyses 104 National Joint Registry

105 Table 5.11 Causes of failure for primary knee replacement implants undertaken between 1 April 2003 and 30 September 2006 that were linked to a HES episode 36 and had a revision also linked to a HES episode Primary knee procedure TKR using cement TKR not using cement Unicondylar knee replacement Total Total Cause of failure Aseptic loosening 60 18% 9 24% 22 32% 91 20% Pain 43 13% 9 24% 22 32% 74 17% Instability 34 10% 7 19% 6 9% 47 10% Infection % 6 16% 5 7% % Dislocation/subluxation 11 3% 3 8% 4 6% 18 4% Malalignment 19 5% 6 16% 3 4% 28 6% Periprosthetic fracture 10 3% 1 3% 3 4% 14 3% Wear of polyethylene component 6 2% 0 0% 2 3% 8 2% Lysis 14 4% 1 3% 1 1% 16 4% Stiffness 23 7% 1 3% 2 1% 26 6% Implant fracture 1 <1% 0 0% 1 1% 2 <1% Component dissociation 2 <1% 1 3% 1 1% 4 1% Other 15 4% 2 5% 11 16% 28 6% 36 Procedures linked to a HES episode were those undertaken in England and mainly in NHS hospitals (see Section 2.2) Table 5.12 Mortality rates and age-and-gender-standardised mortality ratios at 1 year following primary knee replacement for procedures linked to a HES episode 37, Procedure type Number of procedures Deaths Rate 38 (95% CI) SMR (95% CI) Total Cemented TKR Cementless TKR Unicondylar replacement 44,115 38,113 3,461 2, % (1.5% - 1.7%) 1.7% (1.6% - 1.8%) 1.5% (1.2% - 1.9%) 0.7% (0.5% - 1.0%) 0.35( ) 0.36 ( ) 0.35 ( ) 0.17 ( ) 37 Procedures linked to a HES episode were those undertaken in England and mainly in NHS hospitals (see Section 2.2 of Part 2) 38 Calculated using the Kaplan-Meier survival analysis method 4th Annual Report 105

106 Table 5.13 Mortality at 1 year for primary knee replacement procedures undertaken between 1 April 2003 and 30 June 2006 that were linked to a HES episode 39 Factor Category Number of patients Number dying within 1 year Hazard ratio 40 (95% CI) Age < 65 years 20, years 30, ( ) 75+ years 26, ( ) Gender Male 32, Female 44, ( ) Patient physical status P1 Fit and healthy P2 Mild disease not incapacitating P3+ Incapacitating systemic disease or worse 15,028 50,333 12, ( ) 2.2 ( ) Procedure type Total replacement using cement Total replacement not using cement 66,428 5, ( ) Hybrid total replacement 1, ( ) Unicondylar knee replacement 4, ( ) Patello-femoral knee replacement ( ) Provider type NHS hospital Independent hospital 68,449 3, ( ) NHS Treatment Centre 4, ( ) Independent Treatment Centre 1, ( ) 39 Procedures linked to a HES episode were those undertaken in England and mainly in NHS hospital (see Section 2.2 of Part 2) 40 Relative hazard of death within 1 year of primary knee replacement compared to a patient with a reference level of the factor (hazard ratio=1), adjusted for all other factors included in the analyses 106 National Joint Registry

107 Table 5.14 Length of hospital stay (days) following admission for a primary knee replacement for procedures linked to a HES episode 41, Factor Category Number of patients Average length of stay (days) (95% CI) Adjusted difference in average LOS * (days) (95% CI) Age < 65 years 24, ( ) years 36, ( ) 0.5 ( ) years 27, ( ) 1.7 ( ) 85+ years 3, ( ) 4.3 ( ) Gender Male 39, ( ) 0.0 Female 52, ( ) 0.3 ( ) Patient physical status P1 Fit and healthy P2 Mild disease not incapacitating P3 Incapacitating systemic disease 17,311 59,785 14, ( ) 8.2 ( ) 10.4 ( ) ( ) 1.6 ( ) P4 Life threatening disease ( ) 3.2 ( ) Procedure type Total replacement using cement Total replacement not using cement 73,967 6, ( ) 8.1 ( ) ( ) Hybrid total replacement 1, ( ) -0.3 ( ) Unicondylar knee replacement 4, ( ) -2.1 (-2.3 _ -2.0) Patello-femoral replacement ( ) -1.2 (-1.6 _ -0.8) Provider type NHS hospital Independent hospital 81,072 4, ( ) 6.2 ( ) (-2.2 _ -1.9) NHS Treatment Centre 5, ( ) -1.6 (-1.7 _ -1.4) Independent Treatment Centre 1, ( ) -2.7 (-3.1 _ -2.5) 41 Procedures linked to a HES episode were those undertaken in England and mainly in NHS hospital (see Section 2.2 of Part 2) 4th Annual Report 107

108 Part 2 6. Prostheses Used in Hip and Knee Replacement Procedures 108 National Joint Registry

109 6.1 Prostheses Used in Hip Procedures In 2006, 155 different brands of acetabular cups and 176 different brands of femoral stems were recorded: an increase of 36% over 2005 for both stems and cups. This was a result of new suppliers entering the market, the introduction of new brands by existing suppliers and/or improved reporting Background In the NJR 2nd Annual Report of 2004 (pages available on NJR website, a full description was given of the National Institute for Health and Clinical Excellence (NICE) guidance on the selection of prostheses for primary total hip replacement and hip resurfacing arthroplasty, and the subsequent setting up of the Orthopaedic Data Evaluation Panel (ODEP). ODEP provides an independent assessment of clinical outcomes data, submitted by implant manufacturers, on the compliance of brands of total hip and hip resurfacing prostheses with the NICE benchmarks for the effectiveness of primary total hip prostheses. ODEP s main function is to provide an independent assessment of the clinical outcomes data, submitted by manufacturers of prostheses, on the compliance of brands of total hip and hip resurfacing prostheses, with the NICE benchmarks for the effectiveness of primary total hip prostheses. ODEP produced criteria for assessing compliance of products with the NICE guidance. NICE has indicated that the situation will be reviewed in Results of ODEP assessments The ODEP committee reviewed the clinical data submissions and as a result, 54 (40%) brands of femoral stems and 50 (49%) brands of acetabular cups received ODEP ratings. There are however, 52 (51%) brands of acetabular cup and 79 (60%) brands of femoral stem currently being used in England and Wales for which no data has been submitted to the ODEP committee. Some of these may be components intended for revision surgery and therefore not covered by the ODEP rating, but this is currently being investigated. The latest listings for all brands currently being used by hospitals in England and Wales can be seen by visiting the ODEP website on Analysis of results Analysis of the summary data shows that the usage of products meeting the full ten year (10A) benchmark as recommended by NICE is as follows: Cemented Stems: 69.0% (made up of 11 brands out of 72 recorded on NJR). Cementless Stems: 70.6% (made up 8 brands out of 63 recorded on NJR). Cemented Cups: 42.6% (made up 9 brands out of 51 recorded on NJR). Cementless Cups: 4.8% (made up 1 brand out of 51 recorded on NJR). These percentages are only based on clinical outcomes data already submitted to the ODEP committee. Manufacturers may submit additional data that could result in these percentages being revised in the future. Comparison with the 2005 figures shows that the usage of cemented and cementless stems fully compliant with NICE guidelines is similar to 2006, but there has been a decline in the usage of fully compliant cemented and cementless cups Brand sales of conventional total hips and resurfacing prostheses Tables show the most frequently used brands in England and Wales during 2006, as assessed by their rate of entry into NJR. The level of assessment according to ODEP criteria is given in the final column. Table 6.10 provides a summary of procedures where brands of re-surfacing acetabular cups have been used in combination with a conventional stem and a large metal-on-metal femoral head. This represents a 92% increase on last year Combinations of cups and stems For 48,274 hip replacement procedures in the 2006 data, both the cup and stem brand was known, and a total of 776 different combinations of cup and stem brands were recorded. This represents a 2% decrease over The combinations entered into the NJR are listed in Table The most common cup-stem combination was the Exeter V40 stem combined with the Contemporary Duration cup. Highlighted in Table 6.11 are those combinations where the stem manufacturer is different from the cup manufacturer a practice known as mixing and matching. Of the 48,274 procedures included in this chapter, 10,622 (22%) used mixed and matched cup-stem combinations, approximately 3% fewer than in 2005 and th Annual Report 109

110 Table 6.1 Frequency of material chosen for femoral heads in procedures performed in 2006 Table 6.2 Frequency of femoral head sizes for procedures performed in 2006 Material Number of procedures % Head size Number of procedures % 47,103 Metal 35, % Alumina 11, % Zirconia % Total 47,103 47, mm 1, % 26.00mm 2, % 28.00mm 31, % 32.00mm 5, % Other size 5, % Total 47, Femoral head material and size Table 6.1 (above) shows the relative usage of different femoral head materials in patients of different age groups. This year, the ceramic category has been further split into Alumina and Zirconia. The figures are very similar to those in 2005 and 2004 and demonstrate that there has been no change in surgical practice. Table 6.2 (above right) shows the frequency of the different femoral head sizes. The main change compared with 2005 is an increase in the use of heads classified as Other size and an increase in the use of 36mm heads for metal-on-metal articulations. Over half of these Other sized heads were implanted with a resurfacing cup Summary The total number of brands of acetabular cups and femoral stems recorded in NJR has increased significantly. There are 155 brands of acetabular cups (88 in 2004, 110 in 2005) and 176 brands of femoral stems (101 in 2004, 129 in 2005). Although these figures show 22 new cup and 28 new stem brands, none of the brands recorded in 2004 failed to appear in In addition to conventional re-surfacing procedures, there have been almost 3,000 procedures entered into the NJR whereby a re-surfacing cup has been used in conjunction with a large modular head and a conventional stem. Material of femoral heads used in 2006 are very similar to 2004, however, the size of femoral heads used shows an increase in the larger head sizes other head sizes and 32mm. 6.2 Prostheses Used in Knee Procedures Prostheses entered into the NJR 54 brands of total condylar knee prostheses were recorded. In addition, there were 13 brands of unicondylar prostheses, 7 brands of patello-femoral replacement prostheses and 12 brands of hinged prostheses. The number of brands for each prosthesis type either remained the same or increased slightly compared with Table 6.12 shows the brands of total condylar knee replacement prostheses recorded most frequently for TKR and hybrid procedures. Brands of unicondylar prostheses are shown in Table brands of patello-femoral joint replacements were entered into the NJR in 2006 (Table 6.14). Brands of hinged prostheses entered on NJR are shown in Table Usage of fixed versus mobile bearing tibial inserts Tibial inserts recorded in total condylar procedures were predominantly fixed bearing (85%, 44,333) of all procedures using tibial inserts (an increase of 2% on 2005), compared with 15% (7,751) involving mobile bearing tibial inserts, as shown in Table National Joint Registry

111 Table 6.3 Tibial insert type 2006 Tibial insert type All patients % 52,084 Fixed Bearing 44, % Mobile Bearing 7, % 52,084 Table 6.4 Type of cement used in hip and knee replacement procedure cement entered into NJR in 2006 Cement type Hip procedures % Knee procedures % All procedures % 38,758 50,416 89,174 Antibiotic 34, % 47, % 82, % Non Antibiotic 4, % 2, % 6, % 38,758 n/a 50,416 n/a 89,174 n/a 6.3 Cement Use The majority (92%) of procedures involving cement used antibiotic-loaded rather than non antibiotic (Table 6.4), virtually the same as in 2004 and Manufacturers of antibiotic-loaded cement and non-antibiotic cement are given in Tables 6.16 and More than one packet of cement could be entered for a particular procedure. For knee procedures, between 1 and 6 packets were entered for a single procedure. For hip procedures, up to 12 packets were entered. 6.4 Bone Substitute Use Table 6.18 lists the manufacturers of bone substitutes for hip and knee procedures in Although the use of synthetic bone substitute remained relatively low, such products were reported as being used in 494 procedures during 2006, nearly 10% more than 2005 and almost three times as many as in One or two units of bone substitute were recorded for a single knee procedure, whilst up to 5 packets were entered for a hip procedure. 4th Annual Report 111

112 Table 6.5 Cemented cup brands entered during 2006 for hip replacements Manufacturer Brand Total procedures % ODEP rating 25,690 Stryker Howmedica Osteonics CONTEMPORARY 5, % 5A DePuy ELITE PLUS OGEE 4, % 10A DePuy CHARNLEY CEMENTED CUP 2, % 10A Stryker Howmedica Osteonics EXETER DURATION 2, % 10A DePuy CHARNLEY OGEE 1, % 10A DePuy ELITE PLUS CEMENTED CUP 1, % 5B Zimmer ZCA 1, % 7A Smith & Nephew OPERA 1, % 5B Zimmer LOW PROFILE MULLER % DePuy WROBLESKI GOLF BALL % 3B DePuy ULTIMA CEMENTED CUP % 7A Corin CENATOR CEMENTED CUP % 3A Biomet STANMORE-ARCOM % 10A Biomet APOLLO % Pre-entry Biomet M2A CEMENTED CUP % Pre-entry Stryker Howmedica Osteonics ODC % Joint Replacement Instrumentation Ltd FURLONG CEMENTED CUP % 10B Zimmer ZIMMER CEMENTED CUP % 7B Waldemar Link LINK FLANGE CUP % Smith & Nephew REFLECTION CEMENTED % 10A Waldemar Link INTERPLANTA % 10A Biomet ARCOM SHP % 5B Zimmer METASUL-WEBER % 3A Endo Plus (UK) Limited PE-PLUS % 10C Biomet BIOMET MULLER % 5B B Braun / Aesculap CHIRULEN % Zimmer CENTERPULSE MULLER % Zimmer METASUL-MULLER % Mathys Orthopaedics Ltd CCB MATHYS % 10A Implants International EDINBURGH CUP % Biomet CMK CEMENTED CUP % Waldemar Link SNAP FIT % Corin HI-NEK CEMENTED CUP % Smith & Nephew SP % DePuy ELITE PLUS FLANGED % 5B Corin CTI CEMENTED CUP 11 Orthodynamics/Symbios ORTHODYNAMICS 11 7B Stryker Howmedica Osteonics EXETER CEMENTED CUP 10 10A Zimmer SPC 8 Zimmer HEDROCEL ELLIPTICAL 5 Biomet MAINSTREAM MULLER CEMENTED CUP 4 Implants International CCB National Joint Registry

113 Table 6.5 (continued) Manufacturer Brand Total procedures % ODEP rating Implants International MARATHON 4 Biomet ETERNITY CEMENTED CUP 3 DePuy HYLAMER OGEE 3 Ortho-ID POLAR CEMENTED CUP 3 Biomet HEDROCEL ELLIPTICAL 2 Finsbury FREEMAN CUP FINSBURY 2 10C Corin METALOK CEMENTED CUP 1 DePuy ENDURANCE CEMENTED CUP 1 Sovereign Medical BICANA CUP 1 Total 25,690 4th Annual Report 113

114 Table 6.6 Cementless cup brands entered during 2006 for hip replacements Manufacturer Brand Total procedures % ODEP rating 24,979 DePuy PINNACLE 5, % 3A Stryker Howmedica Osteonics TRIDENT 4, % 3A Zimmer TRILOGY 4, % 7A Joint Replacement Instrumentation Ltd CSF 3, % 10B DePuy DURALOC CEMENTLESS CUP 1, % 10A Endo Plus (UK) Limited EPF-PLUS % 3A Smith & Nephew REFLECTION CEMENTLESS % 7B Stryker Howmedica Osteonics ABG II CEMENTLESS CUP % 3A Biomet EXCEED % 3A Zimmer ALLOFIT % 5A Zimmer TRABECULAR METAL CEMENTLESS CUP % Pre-entry Joint Replacement Instrumentation Ltd FURLONG CEMENTLESS CUP % 10B B Braun / Aesculap PLASMACUP CEMENTLESS CUP % Unacceptable Biomet MALLORY-HEAD CEMENTLESS CUP % 5B Stryker Howmedica Osteonics SECURE FIT CEMENTLESS CUP % 5A Endo Plus (UK) Limited BICON-PLUS % 7A Wright Medical UK Ltd ANCAFIT CEMENTLESS CUP % 3A Endo Plus (UK) Limited POLAR CEMENTLESS CUP % Biomet ALIZE % 7B Zimmer CLS CEMENTLESS CUP % 10C Surgicraft SPLIT CUP % Wright Medical UK Ltd LINEAGE % Pre-entry Amplitude SATURNE % 3B Mathys Orthopaedics Ltd MATHYS CEMENTLESS CUP % Pre-entry Biomet BIHAPRO % 7B Corin DC-FIT % Waldemar Link MCMINN % Mathys Orthopaedics Ltd SELEXYS % Finsbury SLF CEMENTLESS CUP (FINSBURY) % 10C Wright Medical UK Ltd PROCOTYL % Biomet UNIVERSAL II % Unacceptable DePuy J-LOC % Zimmer FITMORE % 7B DePuy S-ROM CEMENTLESS CUP % 3A Joint Replacement Instrumentation Ltd FRF % 3A Biomet BIOMEX 12 Pre-entry Wright Medical UK Ltd MATHYS CEMENTLESS CUP 7 DePuy ULTIMA CEMENTLESS CUP 6 3A Biomet M2A CEMENTLESS CUP 4 Pre-entry Biomet PAR 5 RINOWL CEMENTLESS CUP 4 Waldemar Link PRESSFIT 4 DePuy OCTOPUS 2 Endo Plus (UK) Limited BOFOR National Joint Registry

115 Table 6.6 (continued) Manufacturer Brand Total procedures % ODEP rating Implants International RM CEMENTLESS CUP (IMPLANT INTERNATIONAL) 2 Orthodynamics/Symbios NOVAE STICK 2 Waldemar Link DAVIS CEMENTLESS CUP 2 Biomet RANAWAT/BURSTEIN 1 Mathys Orthopaedics Ltd RM CEMENTLESS CUP (MATHYS) 1 10B Orthodynamics/Symbios NOVAE 1 Stryker Howmedica Osteonics RESTORATION GAP2 1 Wright Medical UK Ltd TRANSCEND 1 Total 24,979 4th Annual Report 115

116 Table 6.7 Cemented stem brands entered during 2006 for hip replacements Manufacturer Brand Total procedures % ODEP rating 33,637 Stryker Howmedica Osteonics EXETER 17, % 10A DePuy C-STEM CEMENTED STEM 3, % 7B DePuy CHARNLEY CEMENTED STEM 3, % 10A Zimmer CPT 2, % 7A Biomet STANMORE MODULAR % 10A Zimmer MS % 5B Biomet TAPERLOC CEMENTED STEM % Waldemar Link SP II CEMENTED STEM % 10A DePuy ELITE PLUS CEMENTED STEM % 5A Joint Replacement Instrumentation Ltd FURLONG CEMENTED STEM % 10C Zimmer ZMR CEMENTED STEM % Zimmer MULLER STR STEM % 10A Zimmer P10 MULLER % 10A Smith & Nephew SPECTRON % 10A Endo Plus (UK) Limited CPS-PLUS % 3A Zimmer VERSYS CEMENTED STEM % 3A Zimmer MEM % 10A DePuy ULTIMA CEMENTED STEM % 10C Corin TAPERFIT CEMENTED STEM % 5B Smith & Nephew CPCS % Pre-entry Corin OXFORD UNIVERSAL HIP (CORIN) CEMENTED STEM % Zimmer REVITAN CEMENTED STEM % DePuy SUMMIT CEMENTED STEM % Pre-entry Biomet OLYMPIA % 5B Biomet BIMETRIC CEMENTED STEM % 10A Biomet MODULAR INTERLOC % Biomet MONOBLOC STANMORE % 10A Waldemar Link MP NECK CEMENTED STEM % B Braun / Aesculap CENTRAMENT % 3B Finsbury ADEPT CEMENTED STEM % Pre-entry Biomet AURA II CEMENTED STEM % Pre-entry B Braun / Aesculap BICONTACT CEMENTED STEM % 10C Biomet CMK CEMENTED STEM % 10C Zimmer THRUST PLATE % Implants International EDINBURGH % Zimmer MAYO CEMENTED STEM % Mathys Orthopaedics Ltd CCA CEMENTED STEM % 10A Wright Medical UK Ltd PROFEMUR CEMENTED STEM % Pre-entry Corin TRIFIT CEMENTED STEM % Biomet OXFORD UNIVERSAL HIP (BIOMET) CEMENTED STEM % Corin CENATOR CEMENTED STEM % 3A Corin HI-NEK CEMENTED STEM % Zimmer VERSYS HERITAGE % Pre-entry 116 National Joint Registry

117 Table 6.7 (continued) Manufacturer Brand Total procedures % ODEP rating Endo Plus (UK) Limited SLR-PLUS CEMENTED STEM % B Braun / Aesculap PREVISION CEMENTED STEM 12 Corin CTI CEMENTED STEM 12 DePuy WROBLESKI RESECTION 9 Corin CENTRAFIX 8 Finsbury FREEMAN CEMENTED FINSBURY 7 10C Biomet KENT HIP 6 DePuy HOWSE II 6 B Braun / Aesculap EXCIA-CEMENTED 5 Orthodynamics/Symbios LMT 5 7B Stryker Howmedica Osteonics GMRS 5 B Braun / Aesculap HUCKSTEP CEMENTED STEM 4 DePuy ENGAGE 4 Smith & Nephew TRI TAPER CEMENTED STEM 4 Van Straten Medical CUSTOM DEVICE 4 Waldemar Link MEGA SYSTEM 4 Van Straten Medical ECOFIT 3 Biomet MALLORY-HEAD CEMENTED STEM 2 Endo Plus (UK) Limited ENDOPLUS CEMENTED 2 Orthodynamics/Symbios CANNULOK CEMENTED STEM 2 Stryker Howmedica Osteonics ACCOLADE CEMENTED 2 B Braun / Aesculap METHA CEMENTED 1 DePuy CHARNLEY EVOLUTION CEMENTED STEM 1 DePuy LPS 1 Implants International AJS 1 Implants International MARATHON CEMENTED STEM 1 Smith & Nephew ECHELON CEMENTED STEM 1 Stanmore Implants Worldwide STANMORE MODULAR 1 Total 33,637 4th Annual Report 117

118 Table 6.8 Cementless stem brands entered during 2006 for hip replacements Manufacturer Brand Total Procedures % ODEP rating 18,506 DePuy CORAIL 6, % 10A Joint Replacement Instrumentation Ltd FURLONG HAC 3, % 10A Endo Plus (UK) Limited SL-PLUS CEMENTLESS STEM 1, % 10A Smith & Nephew SYNERGY CEMENTLESS STEM % 5A Stryker Howmedica Osteonics ABG II CEMENTLESS STEM % 5B Stryker Howmedica Osteonics OMNIFIT CEMENTLESS STEM % 10A Zimmer CLS CEMENTLESS STEM % 10A Stryker Howmedica Osteonics ACCOLADE % 3B Zimmer VERSYS CEMENTLESS STEM % 3A Biomet BIMETRIC CEMENTLESS STEM % 10A DePuy S-ROM CEMENTLESS STEM % 7B Biomet MAINSTREAM MULLER CEMENTLESS STEM % Pre-entry Biomet TAPERLOC CEMENTLESS STEM % 10B Wright Medical UK Ltd PROFEMUR CEMENTLESS STEM % Pre-entry DePuy SUMMIT CEMENTLESS STEM % 3A DePuy KAR % B Braun / Aesculap BICONTACT CEMENTLESS STEM % 10C DePuy SOLUTION CEMENTLESS STEM % Biomet AURA II CEMENTLESS STEM % Pre-entry Finsbury FREEMAN CEMENTLESS % 10C Waldemar Link DAVIES CEMENTLESS STEM % Smith & Nephew ECHELON CEMENTLESS STEM % DePuy REEF % Wright Medical UK Ltd ANCAFIT CEMENTLESS STEM % 3A Orthodynamics/Symbios CANNULOK CEMENTLESS STEM % DePuy AML % 10B Zimmer ZWEYMULLER % 10A Stryker Howmedica Osteonics RESTORATION CEMENTLESS STEM % Zimmer ALLOCLASSIC CEMENTLESS STEM % 10A Biomet BIHAPRO MK III % 7B Mathys Orthopaedics Ltd CBC % Pre-entry Corin PROXIMA % 5A Biomet CONELOCK % Corin C FIT % DePuy IPS % 5A Corin PANATOMIC CEMENTLESS STEM % DePuy PROXIMA % Mathys Orthopaedics Ltd TWINSYS CEMENTLESS STEM % Pre-entry Smith & Nephew BIRMINGHAM HEAD RESECTION STEM % B Braun / Aesculap EXCIA % 3A Smith & Nephew ANTHOLOGY % Corin TRIFIT CEMENTLESS STEM 9 Biomet MALLORY-HEAD CEMENTLESS STEM 5 10B 118 National Joint Registry

119 Table 6.8 (continued) Manufacturer Brand Total Procedures % ODEP rating International Orthopaedics Ltd HACTIV 5 Pre-entry Stryker Howmedica Osteonics ABG I CEMENTLESS STEM 5 7A Waldemar Link CFP 4 Zimmer WAGNER CONE 4 3B Stryker Howmedica Osteonics CALCAR REP 3 Surgicraft ESOP 3 Zimmer ANATOMIC 3 Biomet REACH 2 Corin HI-NEK CEMENTLESS STEM 2 Orthodynamics/Symbios BRADLEY 2 Stryker Howmedica Osteonics GMRS CEMENTLESS 2 Zimmer MAYO CEMENTLESS STEM 2 5A B Braun / Aesculap HUCKSTEP CEMENTLESS STEM 1 B Braun / Aesculap METHA 1 Corin ALPHA FIT 1 DePuy REPLICA 1 Endo Plus (UK) Limited ENDOPLUS CEMENTLESS HIP 1 Endo Plus (UK) Limited ENDOPLUS CEMENTLESS REVISION STEM 1 Zimmer ZMR CEMENTLESS STEM 1 Total 18,506 4th Annual Report 119

120 Table 6.9 Brands of resurfacing heads entered into the NJR in 2006 Manufacturer Brand Total procedures % ODEP rating 6,314 Smith & Nephew BHR RESURFACING HEAD 3, % 7A Corin CORMET 2000 RESURFACING HEAD % 3A DePuy ASR RESURFACING HEAD % Pre-entry Zimmer DUROM RESURFACING HEAD % Pre-entry Wright Medical UK Ltd CONSERVE % 3A Finsbury ADEPT RESURFACING HEAD % Pre-entry Biomet RECAP RESURFACING HEAD % Pre-entry Stryker Howmedica Osteonics MITCH TRH % Pre-entry International Orthopaedics Ltd ICON % Pre-entry Van Straten Medical ACCIS RESURFACING HEAD % Tricon/Medacta CORNWALL RESURFACING HEAD % Pre-entry Total 6, National Joint Registry

121 Table 6.10 Procedures using a resurfacing cup with a conventional stem in 2006 Manufacturer Brand Total Procedures % 2,856 DePuy ASR RESURFACING CUP % Smith & Nephew BHR RESURFACING CUP % Zimmer DUROM RESURFACING CUP % Biomet RECAP RESURFACING CUP % Finsbury ADEPT RESURFACING CUP % Corin CORMET 2000 RESURFACING CUP % Midland Medical Technologies Ltd BHR RESURFACING CUP % Wright Medical UK Ltd CONSERVE PLUS % Stryker Howmedica Osteonics MITCH TRH CUP 4 0.1% Tricon/Medacta ESKA RESURFACING CUP 1 Total 2,856 4th Annual Report 121

122 Table 6.11 Top 20 Cup - Stem combinations recorded in the NJR in 2006 Stem manufacturer Stem brand Cup manufacturer Cup Brand Number of procedures 48,264 % Mix and match? Stryker Howmedica Osteonics EXETER V40 Stryker Howmedica Osteonics CONTEMPORARY 5, % No DePuy CORAIL DePuy PINNACLE 4, % No Joint Replacement Instrumentation Ltd FURLONG HAC Joint Replacement Instrumentation Ltd CSF 3, % No Stryker Howmedica Osteonics EXETER V40 Stryker Howmedica Osteonics TRIDENT 2, % No Stryker Howmedica Osteonics EXETER V40 DePuy ELITE PLUS OGEE 2, % Yes Stryker Howmedica Osteonics EXETER V40 Stryker Howmedica Osteonics EXETER DURATION 1, % No DePuy CHARNLEY CEMENTED STEM DePuy CHARNLEY CEMENTED CUP 1, % No DePuy CHARNLEY CEMENTED STEM DePuy CHARNLEY OGEE 1, % No Stryker Howmedica Osteonics EXETER V40 Zimmer TRILOGY 1, % Yes Zimmer CPT Zimmer TRILOGY % No DePuy C-STEM CEMENTED STEM DePuy ELITE PLUS OGEE % No Zimmer CPT Zimmer ZCA % No DePuy C-STEM CEMENTED STEM DePuy ELITE PLUS CEMENTED CUP % No Stryker Howmedica Osteonics EXETER V40 DePuy ELITE PLUS CEMENTED CUP % Yes DePuy CORAIL DePuy DURALOC CEMENTLESS CUP % No Endo Plus (UK) Limited SL-PLUS CEMENTLESS STEM Endo Plus (UK) Limited EPF-PLUS % No Stryker Howmedica Osteonics ACCOLADE Stryker Howmedica Osteonics TRIDENT % No DePuy C-STEM CEMENTED STEM Smith & Nephew OPERA % Yes Zimmer VERSYS CEMENTLESS STEM Zimmer TRILOGY % No DePuy C-STEM CEMENTED STEM DePuy PINNACLE % No Other 10, % No Other 5, % Yes 122 National Joint Registry

123 Table 6.12 Total Condylar knee brands entered into NJR in 2006 for total knee replacements and hybrid and revision procedures Manufacturer Brand Total procedures % 52,099 DePuy PFC SIGMA BICONDYLAR KNEE 18, % Zimmer NEXGEN 6, % Biomet AGC 6, % Stryker Howmedica Osteonics SCORPIO 4, % Smith & Nephew GENESIS 2 2, % Endo Plus (UK) Limited ENDOPLUS BICONDYLAR KNEE 2, % DePuy LCS 2, % Stryker Howmedica Osteonics KINEMAX 2, % Smith & Nephew PROFIX 1, % Wright Medical UK Ltd ADVANCE BICONDYLAR KNEE % Biomet MAXIM % Finsbury MRK % Wright Medical UK Ltd INSALL-BURSTEIN % Stryker Howmedica Osteonics TRIATHLON % Corin ROTAGLIDE % Zimmer NK2 BICONDYLAR KNEE % Exactech (UK) Ltd OPTETRAK % B Braun / Aesculap COLUMBUS % Zimmer INSAL-BURSTEIN % Zimmer FS % Biomet VANGUARD % Van Straten Medical CCI % B Braun / Aesculap E-MOTION BICONDYLAR KNEE % Biomet CKS % Zimmer INNEX % Corin ROTAGLIDE % Biomet ALPINA % Waldemar Link TACK % Smith & Nephew LEGION % Joint Replacement Instrumentation Ltd JRI BICONDYLAR KNEE % Finsbury DBK % Biomet OXFORD TMK % Smith & Nephew JOURNEY 22 Corin AMC 21 Implants International ST LEGER 17 Sovereign Medical CCI 16 Wright Medical UK Ltd ADVANTIM 15 Orthopaedic Surgical Implants Ltd ACTIVE BICONDYLAR KNEE 11 Intavent - Orthofix OPTETRAK 6 Endo Plus (UK) Limited TC PLUS 5 Smith & Nephew GENESIS 4 Smith & Nephew RENASYS BICONDYLAR KNEE 4 Zimmer SAL 3 4th Annual Report 123

124 Table 6.12 (continued) Manufacturer Brand Total procedures % DePuy AMK 3 DePuy PFC BICONDYLAR KNEE 3 Wright Medical UK Ltd AVANCE 2 v Zimmer NATURAL KNEE 2 Amplitude SCORE 1 Biomet RHK 1 Biomet ROCC 1 Finsbury FS Mathys Orthopaedics Ltd MATHYS BICONDYLAR KNEE 1 Wright Medical UK Ltd 913 SYSTEM 1 Total 52,099 Table 6.13 Unicondylar knee brands entered into the NJR in 2006 for unicondylar knee procedures Manufacturer Brand Total procedures % Cemented Cementless 5,338 Biomet OXFORD III 3, % Yes Yes Zimmer MG UNI % Yes No DePuy PRESERVATION % Yes No Corin ACM/UNIGLIDE % Yes Yes Waldemar Link SLED % Yes No Stryker Howmedica Osteonics EUIS % Yes No Smith & Nephew GENESIS UNI % Yes Yes Endo Plus (UK) Limited UC-PLUS % Yes No Mathys Orthopaedics Ltd MATHYS UNICONDYLAR KNEE % Yes Yes Biomet OXFORD UNI 6 0.1% Yes No B Braun / Aesculap E-MOTION UNICONDYLAR KNEE 5 0.1% Yes Yes Wright Medical UK Ltd ADVANCE UNICONDYLAR KNEE 4 0.1% Yes Yes Biomet REPICCI 1 Yes Yes Total 5, National Joint Registry

125 Table 6.14 Patello-femoral joint brands entered into the NJR in 2006 for patello-femoral joint replacement procedures Manufacturer Brand Total procedures % 495 Stryker Howmedica Osteonics AVON % Wright Medical UK Ltd FPV % Smith & Nephew COMPETITOR % Waldemar Link LUBINUS PF 7 1.4% Corin LEICESTER 4 0.8% Wright Medical UK Ltd WRIGHT MEDICAL PF 4 0.8% Biomet PERFORMANCE PF 1 0.2% Total 495 Table 6.15 Fixed and rotating hinged knee brands 2006 Manufacturer Brand Total procedures % 677 Waldemar Link ENDO ROTATING HINGE % Stryker Howmedica Osteonics MRH % Zimmer NEXGEN HINGE TYPE % DePuy NOILES % Biomet BIRMINGHAM ROT HINGE % Biomet STANMORE HINGE % Endo Plus (UK) Limited RT PLUS % Stanmore Implants Worldwide SMILES HINGED/LINKED KNEE % Waldemar Link MC 8 1.2% Waldemar Link ENDO HINGE 6 0.9% Biomet OSS 4 0.6% Wright Medical UK Ltd GUARDIAN HINGED/LINKED KNEE 4 0.6% Total 677 4th Annual Report 125

126 Table 6.16 Brands of antibiotic bone cement entered into the NJR in 2006 Manufacturer Brand Number % 103,540 Schering-Plough PALACOS ANTIBIOTIC 32, % Heraeus Medical PALACOS ANTIBIOTIC 30, % DePuy CMW ANTIBIOTIC LOADED CEMENT 13, % Stryker Howmedica Osteonics SIMPLEX ANTIBIOTIC 12, % Biomet PALACOS ANTIBIOTIC 11, % DePuy CMW BONE CEMENT 1, % Heraeus Medical PALACOS ANTIBIOTIC % Heraeus Medical PALAMED % Biomet OSTEOPAL ANTIBIOTIC % Biomet CMW ANTIBIOTIC LOADED CEMENT 40 DePuy SMARTSET/ENDURANCE 38 Biomet OPTIVAC REGULAR 15 DePuy CEMVAC ANTIBIOTIC LOADED CEMENT 4 Smith and Nephew WRIGHT MEDICAL BONE CEMENT 1 Total 103,540 Table 6.17 Brands of non-antibiotic bone cement entered into the NJR in 2006 Manufacturer Brand Number % 8,676 Stryker Howmedica Osteonics SIMPLEX 3, % Schering-Plough PALACOS 2, % DePuy CMW BONE CEMENT 1, % Biomet PALACOS 1, % Heraeus Medical PALACOS % DePuy SMARTSET % Corin CORIPLAST % Biomet OSTEOPAL % Zimmer SULCEM 2 Joint Replacement Instrumentation Ltd SULCEM 1 Total 8, National Joint Registry

127 Table 6.18 Brands of synthetic bone substitute entered into the NJR in 2006 Manufacturer Brand Number % 494 Endo Plus (UK) Limited ENDOPLUS BONE SUBSTITUTE % Stryker Howmedica Osteonics BONESAVE % Wright Medical UK Ltd OSTEOSET % Synthes DBX % ApaTech Products APATECH BONE SUBSTITUTE % Corin BIOFUSE % Endo Plus (UK) Limited ALLOGRAN (ENDOPLUS) 8 1.6% Synthes SYNTHES BONE SUBSTITUTE 8 1.6% Endo Plus (UK) Limited STIMULAN (ENDOPLUS) 6 1.2% Stryker Howmedica Osteonics SCORPIO 6 1.2% DePuy CONDUIT 4 0.8% Joint Replacement Instrumentation Ltd JRI BONE SUBSTITUTE 4 0.8% Biomet ENDOBON 2 0.4% Surgicraft SURGICRAFT 2 0.4% DePuy GRAFTON 1 0.2% Endo Plus (UK) Limited B-GRAN 1 0.2% Quadrant Medical Ltd CORTOSS 1 0.2% Total 494 4th Annual Report 127

128 Part 2 Appendices 128 National Joint Registry

129 Appendix 1 Assessment Criteria for Total Hip Prostheses Utilised by the Orthopaedic Data Evaluation Panel (ODEP) Pre-entry benchmark products Entry benchmark Full benchmark Manufacturers are requested to keep ODEP informed of all commercially available prostheses that are involved in postmarket clinical follow-up studies. (This need not include products still in development) The details should consist of: Number of centres Number of surgeons Number of patients 3 years Level A Acceptable evidence Failure rate of 3% or less Kaplan Meier survivorship submitted 95% confidence intervals to include benchmark All UK implanting centres identified All product failures identified A list provided of all studies (published or unpublished) including all initiated by the manufacturer All English and Welsh data now being entered into NJR 5 years Level A Acceptable evidence Failure rate of 5% or less Kaplan Meier survivorship submitted 95% confidence intervals to include benchmark All UK implanting centres identified Data beyond developing centre submitted A list provided of all studies (published or unpublished) including all initiated by the manufacturer All English and Welsh data now being entered into NJR 7 years Level A Acceptable evidence Failure rate of 7% or less Kaplan Meier survivorship submitted 95% confidence intervals to include benchmark All UK implanting centres identified Data beyond developing centre/s submitted A list provided of all studies (published or unpublished) including all initiated by the manufacturer All English and Welsh data now being entered into NJR 10 years Level A Strong evidence Failure rate of 10% or less Cohort of more than 500 joints at start of study All product failures identified Kaplan Meier survivorship at 10 years on acceptable size cohort Registry data or multicentre (3 or more centres including non developing) Methodology of study All UK implanting centres identified ODEP will then list these products for surgeons information Level B Weak evidence Acceptable failure rate Study results submitted Failures identified Level B Weak evidence Acceptable failure rate Study results submitted Failures identified Level B Weak evidence Acceptable failure rate Study results submitted Failures identified Level B Reasonable evidence Failure rate of 10% or less Multicentre (more than one) data submitted Data beyond developing centre/s submitted Level C Weak evidence (products given two years to improve data or they are deemed unacceptable) Failure rate of 10% or less Study results submitted Products that do not meet the benchmark should only be used as part of a clinical trial Unacceptable evidence Unacceptable evidence Unacceptable evidence Unacceptable evidence Entry benchmark 4th Annual Report 129

130 Glossary 130 National Joint Registry

131 A Acetabular component Acetabular cup (hip) Acetabular prosthesis Arthroplasty ASA The portion of a total hip replacement prosthesis that is inserted into the acetabulum the socket part of a ball and socket joint See Acetabular component See Acetabular component A procedure where natural joint, or part of a natural joint, is replaced by an artificial prosthesis American Society of Anaesthesiology (ASA) scoring system for grading the overall physical condition of the patient as fit and healthy, mild disease, not incapacitating, incapacitating system disease or life threatening disease B Bilateral operation Brand (of prosthesis) Operation performed on both sides, e.g. left and right knee procedures carried out during a single operation The brand of a prosthesis (or implant) is the manufacturer s product name, e.g. the Charnley brand for hips, the Rotaglide Plus brand for knees C Case ascertainment Case mix Cement gun Cement pressuriser Compliance Cup Proportion of all relevant joint replacement procedures performed in England and Wales that are entered in the NJR Term used to describe the variation in the surgical practice in terms of factors such as indications for surgery, patient age, sex etc A pressurised container used to insert bone cement into bony cavities A device used to aid surgeon in optimising the strength of adhesion between bone cement and bone The percentage of all total joint procedures which were performed in an individual unit that have been entered into the NJR within any given period See Acetabular component D Data collections periods for annual report analysis The NJR Annual Report Part 1 is about data collected between 1 April 2006 and 31 March 2007 the 2006/07 financial year The NJR Annual Report Part 2 analyses data on hip and knee procedures undertaken between 1 January and 31 December 2006 inclusive the 2006 Calendar year Data quality Completeness, accuracy and linkability of NJR data F Femoral component (hip) Femoral component (knee) Femoral head Part of total hip joint that is inserted into the femur (thigh bone) of the patient. It normally consists of a stem and head (ball) Portion of a knee prosthesis that is used to replace the articulating surface of the femur (thigh bone) Ball shaped portion of the femur that forms part of the ball and socket hip joint 4th Annual Report 131

132 Femoral prosthesis Femoral stem Portion of a total joint replacement used to replace damaged parts of the femur (thigh bone) See Femoral component (hip) H Head Healthcare provider Hybrid procedure See Femoral head NHS or independent sector organisation that provides healthcare, in the case of the NJR, orthopaedic hip and knee replacement surgery Joint replacement procedure where cement is used on one articulated surface and the other is cementless I Image guided surgery Indication (for surgery) Surgery performed by the surgeon, using real time images (normally x-rays) to help the alignment and positioning of prosthetic components Reason for surgery. The NJR system allows for more than one indication to be recorded L Laminar flow (in theatres) Levy Linkable percentage Linkable procedures System which ensures a continuous flow of clean air around the patient during surgical procedures Additional payment placed on the sales of specific hip and knee implants to cover the costs associated with on-going operations and development of the NJR Linkable percentage is an estimate of the percentage of all relevant procedures that have been entered into the NJR and may be linked via NHS number to other procedures performed on the same patient Procedures entered into the NJR database that are linkable to a patient s previous or subsequent procedures by the patient s NHS number M MDS MDS 1 (MDSv1) MDS 2 (MDSv2) Minimally invasive surgery (MIS) Mixing and matching Modular Minimum data set, the set of data fields collected by the NJR. Some of the data fields are mandatory (i.e. they must be filled in). Fields that relate to patient personal details must only be completed where informed patient consent has been obtained Minimum data set version one, used to collect data from 1 April MDS 1 closed to new data entry on 1 April 2005 Minimum data set version two, introduced on 1 April MDS 2 replaced MDS 1 as official data set on 1 June 2004 Surgery performed using special instruments that allow very small incisions to be made in the tissues of the patient Also know as cross-breeding. Hip replacement procedure where a surgeon chooses to implant a femoral component (incorporating a metallic or ceramic modular head) from one manufacturer with an acetabular component (incorporating a polyethylene bearing surface) from another Component composed of more than one piece, e.g. a modular acetabular cup shell component N NHS NICE benchmark NJR National Health Service See ODEP ratings National Joint Registry for England and Wales. Since 1 April 2003, the NJR has collected and analysed data on hip and knee replacements. It covers both the NHS and independent healthcare sectors to ensure complete recording of national activity in England and Wales 132 National Joint Registry

133 NJR Centre NJR StatsOnline NSTS National co-ordinating centre for the NJR Web facility for viewing and downloading NJR statistics on NHS Strategic Tracing Service. Used to source missing NHS numbers and to determine when patients recorded on the NJR have died O ODEP ODEP ratings OPCS-4 P PASA Patella resurfacing Patello-femoral knee replacement Patello-femoral prosthesis (knee) Patient consent Patient physical status Patient procedure PEDW Primary hip/knee replacement Posterior Lipped Augmentation Device (PLAD) Prosthesis Pulsatile lavage Orthopaedic Data Evaluation Panel of the NHS Purchasing and Supply Agency (PASA) ODEP ratings are the criteria for prostheses for primary total hip replacement product categorisation against NICE benchmarks. The categorisation based on the NICE benchmarks for products pre-entry benchmark (products commercially available that are involved in postmarket clinical follow-up studies); entry benchmark (3 years, 5 years and 7 years; level A acceptable evidence, level B weak evidence); full benchmark (10 years; level A strong evidence, level B reasonable evidence, level C weak evidence). Under each year is a level that is unacceptable evidence, where product should only be used as part of a clinical trial Office of Population, Censuses and Surveys: Classification of Surgical Operations and Procedures, 4th Revision NHS Purchasing and Supply Agency Replacement of the surface of the patella (knee cap) with a prosthesis Procedure involving replacement of femoral condyles and resurfacing of the patella Two piece knee prosthesis that provides a prosthetic articulation surface between the patella and femoral condyles Patient personal details may only be submitted to the NJR where explicit informed patient consent has been given. If a patient does not give consent only the anonymous operation and implant data may be submitted See ASA Type of procedure carried out on a patient e.g. primary total prosthetic replacement using cement Patient Episode Database Wales, the Welsh equivalent to Hospital Episode Statistics (HES) in England First total joint replacement operation performed on any individual patient Special design of cup Orthopaedic implant using joint replacement procedures, e.g. at total hip or a unicondylar knee Pulsed jet of sterile water used to clean the bony surfaces prior to the implantation of a total joint replacement R Re-operation other than revision Resurfacing (hip) Reverse hybrid procedure (hip) Revision hip/knee replacement Procedures following a primary replacement that do not require component removal or replacement Resurfacing of the femoral head with a surface replacement femoral prosthesis and insertion of an acetabular cup with or without cement Hip procedure where the acetabular prosthesis is cemented and the femoral prosthesis is not cemented Operation performed to remove and replace one or more components of a total joint prosthesis for whatever reason 4th Annual Report 133

134 S Socket augmentation Stem Surgical approach Dislocation of the joint See Femoral component (hip) Surgical technique used by a surgeon to expose the bone prior to joint replacement whilst minimising the damage to surrounding tissues T TED stockings THR Thromboprophylaxis TKR Total condylar knee Treatment centre (TC) Trochanter Trochanteric osteotomy Type (of prosthesis) Pressurised stockings worn by patients following surgery. These help to prevent blood clots forming in the blood vessels of the legs Total hip replacement (total hip arthroplasty). Replacement of the femoral head with a stemmed femoral prosthesis and the insertion of an acetabular cup, with or without cement Drug or other post-operative regime prescribed to patients with the aim of preventing blood clot formation in the postoperative period Total knee replacement (total knee arthroplasty). Replacement of both tibial and both femoral condyles, with or without resurfacing of the patella and with or without cement Type of knee prosthesis that replaces the complete contact area between the femur and the tibia of a patient Treatment centres are dedicated units that offer elective and short stay surgery and diagnostic procedures in specialities such as ophthalmology, orthopaedic and a range of other conditions. These include hip and knee replacements. Treatment centres may be NHS or privately funded Bony protuberance of the femur found just below the femoral head Temporary incision of the trochanter, used to aid exposure of hip joint during some types of total hip replacement Type of prosthesis is the generic description of a prosthesis e.g. modular cemented stem (hip), patella-femoral joint (knee) U Unicondylar arthroplasty Unicondylar knee replacement Unilateral operation Replacement of one tibial condylar and one femoral condyl, with or without resurfacing of the patella See Unicondylar arthroplasty Operation performed on one side only e.g. left hip 134 National Joint Registry

135 NJR Centre Contact Details National Joint Registry Northgate Information Solutions (UK) Ltd Peoplebuilding 2 Peoplebuilding Estate Maylands Avenue Hemel Hempstead Hertfordshire HP2 4NW Telephone Fax [email protected] Website 4th Annual Report 135

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