Abstract
Methods
There were 106 men and 94 women (mean age 65 years; 22 - 85). 69 patients had inflammatory arthritis and 131 osteo-arthritis. 27 patients (13 B-P, 14 STAR) had a pre-operative varus/valgus deformity greater than or equal to 20 degrees. Mean follow-up was 48 months (36-72).
Results
Ten patients had died from unrelated cause with satisfactory final outcome assessment. Thirteen ankles (4 STAR, 9 B-P) required revision surgery. The causes of failure were: early deep infection (1 STAR), recurrent deformity (1 STAR, 4BP) aseptic loosening (1STAR, 4 BP), implant failure (1STAR, 1 BP). Six revised ankles (5BP, 1STAR) had pre-operative varus/valgus deformity of 20 degrees or more. AOFAS score for pain improved from 0 to 35 and for function from 30 to 43. There was no difference between the two groups. Pre-operative range of movement was predictive of the final range of movement. Radiographic assessment showed that 30 patients (17BP, 13 STAR) had recurrent deformity (edge loading) as shown by the UHMWPE insert no longer articulating congruently with the metallic components. 14 ankles (8BP, 6 STAR) from this group had pre-operative deformity of 20 degrees or more.
Conclusion
Patients with severe pre-operative deformity had a significant evidence of edge loading and failure resulting in revision surgery. BP replacements failed more frequently than STAR replacements but most BP failures were in ankles with severe pre-operative deformity.
