Factors influencing joint-preserving operations in the treatment of the late stages of osteoarthritis of the hip.

Between November 1983 and December 1992, 136 hips (119 patients) with coxarthritis were operated on using joint-preserving techniques based on the rationale of Pauwels' osteotomy. The criterion for selection was a patient in whom the height of the joint space in the weight-bearing area of the hip was less than 1 mm. The mean age at operation was 48 years and the mean follow-up 109 months (60 to 171). Hips were categorised using Bombelli's classification of osteoarthritis, into atrophic and non-atrophic types. The endpoint was defined as that at which the height of the joint space became less than 1 mm again. The Kaplan-Meier curve showed that the rate of survival of the non-atrophic group was significantly better than that of the atrophic group. Cox's proportional hazard model indicated that the factors influencing the results of joint-preserving operations included Bombelli's classification, postoperative incongruence of the joint and the height of the joint space.