CAULFIELD VIC 3162 AUSTRALIA

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2 REHAB Tech- Monash Rehabilitation Technology Research Unit assume no liability for any claim of adverse effects resulting from misapplication of the information presented here in. While every effort is made to ensure the accuracy of the guide no responsibility or liability will be taken for any inaccuracies. REHABTech is finance and supported by In collaboration with Copyright 1998 All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording or any information storage and retrieval system, without permission in writing from the publisher. Requests for permission to make copies of any part of the work should be addressed to: REHAB Tech- Monash Rehabilitation Technology Research Unit C/- C.G.M.C Kooyong Road CAULFIELD VIC 3162 AUSTRALIA

3 Maximising Component Service Life A prosthesis or orthosis is a device which consists of mechanical and or electrical components which need to be serviced and maintained. The same as any other complex device. When taking a quality approach to using components in a prosthetic and orthotic environment the following are general steps which the provider will incorporate to ensure mechanical integrity of the completed device. This process is in addition to the clinical requirements which will also govern the review of a patient. The aim is to maximise the safe life of the component. 1. Establish information required for choosing a device including Prescription Physical patient details Patient s environment Patient activity Patient compliance 2. Choose known quality devices Compliance to international standards Proven industry practice Other quality related assurance mechanisms 3. Correct procedures for fitting and assembly Appropriate staff to handle relevant steps of procedure Adhere to manufacturer s instructions Use proven industry practices Use recommended sundry items: Always use correct tool Use correct materials, adhesives, solvents, lubricants etc Use correct fasteners and assembly techniques 4. Establish service life and service intervals (compared to patient s clinical review) for the device Based on minimum service intervals including manufacturer s information and warranty Patient activity, environment, prescription and compliance Estimated service life of component after going through steps 1, 2 and 3 Information on service intervals and any component warning signs which may be expected Set review date and action to be taken with regard to servicing 5. Document all aspects of the above Including patient acknowledgment of step 4 6. On review, inspect device Modify estimated inspection interval 7. Repeat 4 6 until service life is reached.

4 Component Service Life Flow Diagram 1 Establish Information required for Chooing a device 2 Choose Known Quality Devices 3 Use correct procedures for fitting and assembly 4 Establish "Service Life" & "Service intervals" 5 Document all previous steps 6 Review and Inspect Yes Is component Safe & in "Service Life" No 7 Discard Component

5 Details On Maximising Component Service Life When deciding the service life of a component we need to know the history of the component, i.e: how many times it was loaded and unloaded, not just how old in terms of weeks, months or years. This does not necessarily depend on whether it was used on the same patient. 1. Establish patient information required for choosing a device: How many steps does the patient take per month? Will this increase or decrease in 6 months (how was this calculated rehab physio on discharge using FIM, other counters or estimated?) Patient weight/height, activity level, alignment, walking and use pattern. Environment for use: (consider dust, salt, isolated environment, carry loads, wet, cold, heat, chemical; sweet, etc) Patient compliance (ability to monitor device or keep future appointments, understanding of requirements) 2. Choose known quality devices: Basis of choice inclusion in the TechGUIDE, compliance to ISO etc. Compliance to other standards on sound professional judgement Avoid choosing due to: hearsay, free sample, cheap, appears similar to a good product, give it a go, what was in stock, fitted some does not appear to be a problem, what is easy, Do not use components for tasks that they were not designed for Quality Assurance requirements 3. Correct procedures for fitting and assembly: Briefly inspect component, if cracks, rust, cross threading or other failure is apparent discard component, (even if brand new ). Use correct and properly operating tools Adhere to any procedures specified by the manufacture. Use correct materials, adhesives, solvents, lubricants etc. Use correct fasteners and assembly techniques, including Loctite and torque settings. Check for scratches and wear marks. Check for grime build up and unexplained noises (patient feedback). Use proven industry practices.

6 Do s and don ts of fitting and assembly. Do not clamp pylons in vices. use old screws and bolts. use incorrect screws and bolts (including threads, head ends and finish). over torque screws and bolts. grind pylons. unduly force components together. use screw driver to open up pylon adaptors. grind and heat bolts, there by changing their properties. drill holes in pylons bend sharp curves in uprights Do use correct cutting tools. use Loctite. discard failed components. look for component faults regularly. use correct torques, with a torque wrench. carefully store fibre composite components. use pylon cutter for carbon fibre pylons. drill snug fit holes for rivets or fasteners. USE COMMON SENSE. 4. Establish service intervals and service life What standard has the component been tested to? What load has it been tested to? Does this vary with manufacturer s load? Look at manufacturer s recommendations ( including adjustments and lubrication) What is the warranty period? Inspect prior to this. How close is the patient to the component limits? What is the component history? Both specific and component type history (experience/failure reports). How will environment factors effect limits? Consider a wearing in review for new items ( equivalent to 1500 Km service in a car). Decide on a minimum inspection interval? Why was this chosen? (ISO testing has 2-3 x 10 6 cycles of regular walking for specified load category 60 Kg, 80 Kg and 100 Kg. ISPO77 testing has 10 6 cycles for regular walking of 105 Kg person.) Car Analogy Requirements: Engine tune every 20,000 km Brakes 50,000 km Tyres 60,000 km Suspension 120,000 km Car warranty is 60,000 km or three years Expected servicing schedule First service 1500 km to check everything is all right 10,000 km to see what is happening and if service intervals are correct Then if OK service at 20,000 km, 30,000 km etc The car is not replaced at the end of the warranty and with servicing has an expected life of 300,000 km ( 5 x times warranty period).

7 5. Document all aspects of the above steps: Patient file Component log, inventory system Mark/identify components with permanent markers, paint pens etc. Patient acknowledgment including: Discuss how device is expected to perform What to do if unusual clicks, noises, etc occur If environment changes (at the beach leg gets wet etc) Ensure patient has a Care for prosthesis book. 6. On review, inspect device Steps in review of components in use. Patient feedback Look for signs of wear, dust, grime, foreign matter, dirt, water, rust and noises. Follow any procedures specified by the manufacturer. Look for signs of problems. Use WD40, RP7 or similar to help remove screws. Clean surfaces in WD40, RP7, metho or kerosene bath. Look for marks or cracks using dye penetrant or, good light with 10X magnification. Concentrate on problem areas. Are the holes still round? Are the threads OK? Are shafts and bearings OK? Has wear caused slack or wobble in the system? If any of these are faulty, replace component. Are there any cracks? If found discard component. Is there any rust,? Treat as cracks. Can continue use if the component: performs its function? is safe? still in its expected service life If yes to all these queries, can reuse. If a component is still to be to be used the date of the inspection, along with who performed the inspection, should be recorded. Re assemble using correct tools, torques and to manufactures recommendations. Replace consumables; bolts, screws, bearings, bumpers, rubbers, etc Mark component with identity. Document what has been done, include service life, in patients file and/or component file. If reusing component go to step 4 and set next inspection date. If in doubt throw it out.

8 7. Repeat steps 4 to 6 until service life is reached What should the next inspection interval be? why? Is the component at its maximum service life? If yes discard. Is patient going to continue with component? If no go back to step 3. Do 4 to 6 until service life is finished. Examples Which situation leaves you liable? (1) If a component is on a patient who will do 1 x million cycles in six months, and you will see them next in 12 months. or (2) Component use on Patient A (who will do 1 million cycles in 4 years), has it for three months, then you reuse the component. Component on Patient B (who will do 1 million in 4 years) and you will see them in 12 months. (1) Common practice but negligent. (2) Uncommon practice yet safe and professional. Real life case: 50 year old lady weighing 85 Kg. Prosthetist described her activity level as low - medium. Pylon fractured after 8 months use. Reasons for failure. Pylon failed by fatigue. Placing the pylon in a vice during assembly initiated the fatigue crack starting fracture. The pylon should never have been fitted to a prosthesis, as it was structurally compromised prior to use. Use correct tools for assembly. The pylon should have been replaced earlier during a routine inspection. No routine inspection occurred. The prosthetist misjudged the activity level of the patient or the patient increased their activity level. Either way the prosthetist had no way of modifying inspection intervals for the patient as none had been set. Even though the pylon would be expected to last 2-3 x 10 6 it failed well short of this due to a scratch in the assembly stage. If an inspection interval had been set prior to this failure the pylon could have been replaced prior to fracture and new inspection intervals set due to different activity level.

9 Kneeling endoskeletal trans femoral breaks foam covers in 3 months so go to exoskeletal. What happens to components? As the components are probably early in their service life use (3 x patients steps per month) after inspection they may be classified as safe to be reused with a reduced service life. Young active patient goes from stance knee to hydraulic. What happens to stance knee? This depends on how long into the service life the knee has gone and how close to the maximum limit of the component. If the remaining service life is low discard, otherwise it may be reused after inspection. What happens to inspection intervals of the new prosthesis. The inspection intervals may decrease due to the extra maintenance required on the hydraulic unit. Interim requires stance knee for patient. Used one in stock. Should it be used? This depends on the remaining service life of the knee in stock and the expected use on the patient. If the patient use (number steps and weight) is less than the remaining service life the knee is suitable, assuming the knee has been monitored and inspected. Patient never comes back for review? Has no time for repairs? This requires choosing components with longer inspection intervals if possible. Using components at a heavier weight category is also a good idea. However patients must be made aware that failure to adhere to reviews leaves them at risk of injuring themselves. Patients with no time for repairs either finish the repair properly or do not start it. Let patients know it is at their risk and responsibility. Patient on border of components limits. Increase inspection intervals and expect shorter service life. Consider using heavier rated components especially if active or they carry lots of equipment. Component used in process of check walk? Depends on how long the components is to be used. If only for 30 minutes (a hundred steps or so) under supervision, just a brief inspection to ensure no cracks, rust, cross threading or other failure is apparent. If to be used longer or without supervision the component should be treated like all others. Only used if the service life is greater than the expected usage.