Spherocentric arthroplasty of the knee. Clinical experience with an average four-year follow-up

We studied eighty-two consecutive spherocentric total knee arthroplasties with an average follow-up of four years (range, two to six years). All patients had either severe preoperative instability or deformity, or both. The over-all functional improvement and symptomatic relief were excellent. Knees with preoperative instability did as well as those with preoperative deformity that were stable. The knees with preoperative valgus deformity were the most likely to have postoperative wound problems or transient nerve palsy, while those with preoperative varus deformity were much more likely to have loosening. Postoperative limb alignment of 7 to 9 degrees of valgus angulation protected against lucency and loosening. No new cases of lucency or loosening appeared after two and one-half years. The infection rate was 4 per cent and the rate of failure due to loosening was 5 per cent. The over-all reoperation rate was 9 per cent. Nine patients (with eleven arthroplasties) died during the follow-up period.