We performed 52 cemented ankle arthroplasties for

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1 Ankle arthroplasty for rheumatoid arthritis and osteoarthritis PROSPECTIVE LONG-TERM STUDY OF CEMENTED REPLACEMENTS Hakon Kofoed, Torben S. Sørensen From Frederiksberg Hospital,Copenhagen, Denmark We performed 52 cemented ankle arthroplasties for painful osteoarthritis (OA) (25) or rheumatoid arthritis (RA) (27) using an ankle prosthesis with a near-anatomical design. We assessed the patients radiologically and clinically for up to 14 years using an ankle scoring system. The preoperative median scores were 29 for the OA group and 25 for the RA group and at ten years were 93.5 and 83, respectively. Six ankles in the OA group and five in the RA group required revision or arthrodesis. Survivorship analysis of the two groups showed no significant differences with 72.7% survival for the OA group and 75.5% for the RA group at 14 years. J Bone Joint Surg [Br] 1998;80-B: Received 4 August 1997; Accepted after revision 31 October 1997 There has been only one study of more than 50 cases which has reported the long-term results of cemented ankle arthroplasty over ten years. 1 No difference was found between patients with OA and RA, which is contrary to results from smaller series of other first-generation constrained prostheses 2-5 in which true comparisons were not made. The estimated survival rate of the arthroplasty was 61% at 15 years, and further use of the prosthesis was abandoned although pain or function were not analysed. We describe a prospective study over 14 years of patients with OA and RA which analyses the clinical and radiological differences between the groups and the long-term survivorship of the prosthesis. H. Kofoed, MD, Consultant Orthopaedic Surgeon, Lecturer in Orthopaedics T. S. Sørensen, MD, Consultant Orthopaedic Surgeon Orthopaedic Clinic, Frederiksberg Hospital, University Hospital of Copenhagen, Nordre Fasanvej 57, DK-2000 Copenhagen, Denmark. Correspondence should be sent to Dr H. Kofoed at 30 Norasvej, DK-2920 Charlottenlund, Denmark British Editorial Society of Bone and Joint Surgery X/98/28243 $2.00 Patients and Methods Between 1981 and 1989 we performed 52 ankle arthroplasties for painful OA or RA. There were 24 patients with OA (25 ankles) and 23 with RA (27 ankles). The median age for those with OA was 61 years (34 to 76) and with RA 55 years (45 to 83). There were no significant differences between the two groups of patients with regard to age and gender. The non-commercial ankle prosthesis consisted of either a two-piece device (1981 to 1985, OA/RA: 12/13) or a three-piece arrangement with a meniscal bearing (1986 to 1989, OA/RA: 13/14). The shape of the components was the same (Fig. 1). The talar implant was an anatomically-shaped metal cap with medial and lateral flanges to cover the medial and lateral facets of the talus. It had a ridge on the upper surface for lateral stabilisation against the tibial component. On the undersurface there was a centrally-placed fin which was inserted in the middle of the dome of the talus. The tibial component had two parallel bars on the upper surface to allow fixation of the component to the subchondral bone of the distal tibia, and the articular surface had a corresponding groove. The prosthesis was congruent, with cylindrical movement allowing for a certain degree of torque except in the neutral position. From 1986 the tibial component was split into a metal-gliding plate carrying the parallel bars and a polyethylene meniscus of the same shape as the lower part of the former tibial component. The metal parts were manufactured from stainless steel. The operative technique was the same for both components which were inserted through an anterior approach under spinal or epidural analgesia and a tourniquet. 6 Antibiotics were given preoperatively to all patients. The tibial and the talar components were fixed with bone cement. Figure 2 shows both prostheses at a follow-up of ten years. The postoperative care was similar for all patients. We used the same ankle evaluation system before operation and at follow-up (Table I). 6 Patients were examined annually and on each occasion radiographs were taken under image intensification. The preoperative films were analysed for ankle axis, bone deficiency, and the presence or absence of arthritis of the talocalcaneal joint. The ankle axis was defined as normal if it was within 3 of varus and 5 of valgus from the vertical axis. Failure of the ankle 328 THE JOURNAL OF BONE AND JOINT SURGERY

2 ANKLE ARTHROPLASTY FOR RHEUMATOID ARTHRITIS AND OSTEOARTHRITIS 329 Fig. 1 The ankle prosthesis. Left: the talar component. Right: the tibial component showing the upper surface (above) and the articular surface with the glide plate and meniscus (below). arthroplasty was defined as revision or arthrodesis. Statistical analysis. We used non-parametric statistics for the analysis of changes during follow-up and for comparison of the two groups of patients. 7 Friedman s test was used within each group of patients to analyse changes in scores during follow-up. Only patients followed every year during the periods in question (six and ten years) were used in the tests. When there was a significant difference, the annual scores were compared with the first-year values as the control. The Mann-Whitney test was used for the comparison of score values between the two groups of patients, and the chi-squared test to compare failure rates. The level of significance was set at Survival analysis of the arthroplasties was performed according to the method of Murray, Carr and Bulstrode. 8 Results Nine patients (nine ankles), four with OA and five with RA, died during the follow-up period from causes unrelated to the ankle arthroplasty. The median time from operation to Fig. 2a Fig. 2b Radiographs after ten years showing the two-component prosthesis (a,b) and the three-component with a meniscal element (c,d). Fig. 2c Fig. 2d VOL. 80-B, NO. 2, MARCH 1998

3 330 H. KOFOED, T. S. SØRENSEN Table I. Scoring system used throughout the study Score Pain No pain 50 Starting pain 40 Pain walking levels 35 Occasional pain 35 Loading pain always 15 Pain at rest or spontaneously 0 Function Tip-toe walking 3 Heel walking 3 One-leg standing 6 No use of walking support 6 No use of stabilising foot wear 6 Normal cadence during staircase walking 6 Mobility (max 20) Flexion (degrees) > to 29 3 <15 1 Extension (degrees) > to 9 3 <5 1 Supination (degrees) > to 29 2 <15 1 Pronation (degrees) > to 19 2 <10 1 Valgus during loading (degrees) <5 2 5 to 10 1 >10 0 Varus during loading (degrees) <4 2 4 to 7 1 >7 0 Evaluation Excellent 85 to 100 Good 75 to 84 Fair 70 to 74 Not acceptable <70 death was 7.5 years (2 to 10). One patient with OA (one ankle) was lost to further follow-up after three years. Eleven ankles (11 patients), six with OA and five with RA (p > 0.6), were considered to be failures because revision (five ankles) or arthrodesis (six ankles) had been required. The median time from operation to revision or arthrodesis was four years (0.8 to 7.3) for OA and five years (4.2 to 8.8) for RA. The remaining patients (41 ankles) were followed for a median time of nine years (6 to 14). Table II gives the survivorship analysis for the arthroplasties and Figure 3 shows the survivorship curves for OA and RA with 95% confidence limits. The score values for pain, function and mobility were all significantly improved by the operation; this applied equally for OA and RA, but the preoperative and postoperative scores of function were lower in patients with RA (Table III). In the OA group we followed 13 ankles annually for six years and eight of these every year for ten years and in the RA group 15 were followed for six years and seven every year for ten years. The median pain, function and mobility scores were unchanged for all patients (Table IV). There was no development of secondary osteoarthritis of the subtalar joints in patients with OA. Spontaneous bony ankylosis of the talocalcaneal joints occurred in five of the 27 ankles with RA during the follow-up. Complications. There was one deep infection in one patient with RA at five years which was treated by arthrodesis. Other failures were treated by revision (5) or arthrodesis (5). Discussion It has often been claimed that ankle arthroplasty, if used at all, should be reserved for patients with polyarthritis who have small physical demands. Those with OA should not be offered the operation because the prosthesis may fail rapidly; 2,9 arthrodesis should normally be used. These statements have been based on evidence from retrospective studies of ankle arthrodesis which have been compared with the short- and middle-term results of early studies on ankle arthroplasty. The latter were mediocre possibly due to technical complications, the inability to correct the tibiopedal axis and incongruent or unstable prostheses. Incongruent and multi-axial designs (TPR, Irvine, Newton) or designs which are too constrained (Oregon, Bech- Steefee) have shown inferior results compared with congruent designs with cylindrical motion (St. Georg, ICLH, Mayo). Some previous series have shown moderately successful medium-term results after cemented arthroplasty. 1,10-13 Controversy remains as to whether the results are better for OA than RA. Our results showed only slight clinical differences in ankle arthroplasty for the two groups and there was no difference in the survival rate. The effectiveness of the prosthesis in relieving pain was the same in both groups. Overall, 88.5% of patients were virtually without ankle pain for activities of daily living. It was also noticed that in both OA and RA the results assessed at one year persisted. Radiological analysis showed that patients with OA did not develop subtalar arthritis, a problem seen commonly after ankle arthrodesis. 14,15 The results of previous studies on ankle arthrodesis have been very variable Rheumatoid arthritis seems to have the worst outcome after this procedure, 21,22 but OA also has a high failure rate of about 20% nonunion and about 15% deep infection. 17 Only two studies have compared ankle arthrodesis with arthroplasty, 22,23 and they found better results for the latter. The indication for each operation is still to be defined. In our series of cemented ankle arthroplasties followed for 14 years and performed for both OA and RA, 75% survived. These results have to be compared with an 85% survival rate at ten years for cementless prostheses. 24 Ankle THE JOURNAL OF BONE AND JOINT SURGERY

4 ANKLE ARTHROPLASTY FOR RHEUMATOID ARTHRITIS AND OSTEOARTHRITIS 331 Table II. Life table for ankle arthroplasties in osteoarthritis (OA) and rheumatoid arthritis (RA) Years Annual Annual since Number Lost to Number failure rate success rate Survival rate operation at start Failure Withdrawn follow-up at risk (%) (%) (%) Osteoarthritis 0 to to to to to to to to to to to to to to Rheumatoid arthritis 0 to to to to to to to to to to to to to to Fig. 3a Fig. 3b Comparative survivorship analysis of OA (a) and RA (b) with 95% confidence limits. Table III. Median (range) preoperative and postoperative scores at one year Preoperative Postoperative Total Pain Function Mobility Total Pain Function Mobility OA (8 to 47) (0 to 15) (0 to 21) (7 to 16) (70 to 98) (35 to 50) (15 to 30) (11 to 18) RA (7 to 37) (0 to 15) (0 to 12) (6 to 13) (74 to 98) (40 to 50) (12 to 30) (12 to 18) p value <0.05 NS <0.01 NS <0.02 NS <0.01 NS VOL. 80-B, NO. 2, MARCH 1998

5 332 H. KOFOED, T. S. SØRENSEN Table IV. Median (range) total scores for 41 ankle arthroplasties followed for up to ten years. The 11 arthroplasties considered as failures are excluded. For the statistical analyses (see text), only the score values for the patients followed every year during the period in question (six or ten years) were used Follow-up year Osteoarthritis Number Median Range 71 to to to to to to to to to to 96 Rheumatoid arthritis Number Median Range 77 to to to to to to to to to to 98 prostheses which use biological fixation have been shown to give better results than cemented prostheses. 25,26 Instruments and a surgical technique designed to achieve better alignment, together with a cementless version of the present prosthesis, may increase survivorship. The results may then compare with those obtained for replacement arthroplasty of other joints. Although none of the authors have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article, benefits have been or will be received but are directed solely to a research fund, educational institution, or other non-profit institution with which one or more of the authors is associated. References 1. Kitaoka IIB, Patzer GL, Ilstrup DM, Wallrichs SL. Survivorship analysis of the Mayo total ankle arthroplasty. J Bone Joint Surg [Am] 1994;76-A: Murray WR, Pfeffinger LI, Teasdale RD. Total ankle arthroplasty: a joint too far (abst). J Bone Joint Surg [Br] 1981;63-B: Bolton-Maggs BG, Sudlow RA, Freeman MAR. Total ankle arthroplasty: a long-term review of the London Hospital experience. J Bone Joint Surg [Br] 1985;67-B: Jensen NC, Krøner K. Total ankle joint replacement: a clinical follow-up. Orthopedics 1992;15: Hay SM, Smith TW. Total ankle arthroplasty: a long-term review. Foot 1994;4: Kofoed H. Cylindrical cemented ankle arthroplasty: a prospective series with long-term follow-up. Foot Ankle Int 1995;16: Siegel S, Castellan NJ Jr. Nonparametric statistics for the behavioural sciences. Sydney: 2nd ed., McGraw-Hill Book Co, Murray DW, Carr AJ, Bulstrode C. Survival analysis of joint replacements. J Bone Joint Surg [Br] 1993;75-B: Hamblen DL. Editorial. Can the ankle joint be replaced? J Bone Joint Surg [Br] 1985;67-B: Engelbrecht E. Ersatz der grossen körpergelenke (ausser hüfte). Der Chirurg 1981;52: Kirkup J. Richard Smith ankle arthroplasty. J R Soc Med 1985;78: Johnson KA. Replacement arthroplasty of the foot and ankle: total ankle arthroplasty. In: Johnson KA, ed. Surgery of the foot and ankle. New York: Raven Press, 1989: Carlsson ÅS, Henricson A, Linder L, Nilsson J-Å, Redlund- Johnell I. A survival analysis of 52 Bath & Wessex ankle replacements. Foot 1994;4: Kenwright J. Arthrodesis of the knee and ankle joint. Thesis. Oxford, Leicht P, Kofoed H. Subtalar arthrosis following ankle arthrodesis. Foot 1992;2: Lance E, Paval A, Fries I, Larsen I, Patterson RL Jr. Arthrodesis of the ankle joint: a follow-up study. Clin Orthop 1979;142: Morrey BF, Wicdeman GP. Complications and long-term results of ankle arthrodeses following trauma. J Bone Joint Surg [Am] 1980; 62-A: Davis RJ, Millis MB. Ankle arthrodesis in the management of traumatic ankle arthrosis: a long-term retrospective study. J Trauma 1980;20: Lynch AF, Bourne RB, Rorabeck CH. The long-term results of ankle arthrodesis. J Bone Joint Surg [Br] 1988;70-B: Moran CG, Pinder IM, Smith SR. Ankle arthrodesis in rheumatoid arthritis: 30 cases followed for 5 years. Acta Orthop Scand 1991;62: Cracchiolo A III, Cimino WR, Lian G. Arthrodesis of the ankle in patients who have rheumatoid arthritis. J Bone Joint Surg [Am] 1992; 74-A: McGuire MR, Kyle RF, Gustilo RB, Premer RF. Comparative analysis of ankle arthroplasty versus ankle arthrodesis. Clin Orthop 1988;226: Kofoed II, Stürup J. Comparison of ankle arthroplasty and arthrodesis: a prospective series with long-term follow-up. Foot 1994;4: Takakura Y, Tanaka Y, Sugimoto K, Tamai S, Masuhara K. Ankle arthroplasty: a comparative study of cemented metal and uncemented ceramic prostheses. Clin Orthop 1990;252: Takakura Y. Results of total ankle arthroplasty, symposium: surgical management of ankle arthritis. Kaohsiung, Taiwan. First Academic Congress of Asian C.I.P., 1996: Buechel FF, Pappas MJ. Survivorship and clinical evauation of cementless, meniscal-bearing total ankle replacements. Semin Arthroplasty 1992;3: THE JOURNAL OF BONE AND JOINT SURGERY