[Femoral osteotomy for severe hip osteoarthritis: an actuarial analysis of results].

INTRODUCTION

In cases of severe hip osteoarthritis in young patients, the intertrochanteric osteotomy can delay total hip arthroplasty. The main advantage of the osteotomy is to preserve the bone stock. The main disadvantages are the lasting postoperative invalidity and the varying longterm success rate. Our aim was to quantify these disadvantages using survivorship analysis.

MATERIAL AND METHODS

The study included 64 patients (65 osteotomies) ranging from 16 to 68 years. The osteotomies were performed between 1975 and 1987. The osteoarthritis was stage III or IV, with a joint space less than 50 per cent. Osteoarthritis was primitive in 25 cases and secondary in the others. The osteotomy always included a medial displacement of the shaft according to the principle of Mac Murray's procedure, but also 22 cases (33.8 per cent) had a varus angulation and 19 (29.2 per cent) a valgus angulation. The preoperative pain score according to the Merle d'Aubigné (MDA) grading was 2.6 (1 to 4) and the global functional score was 11.1 (5 to 15). The patients were reviewed in 1991 and examined clinically and radiographically.

RESULTS

The results of the 65 cases were distributed into 3 groups: -29 cases having reached the follow-up without difficulty, -7 patients were lost for follow-up examination, 6 of these latter than 9 years, -29 patients taking osteotomy failure as a pain lesser than the 3 MDA score. The postoperative delay to obtain the best functional result was 6 to 24 months (mean: 13.65). This result ranged from 5 to 17 MDA score (mean: 15) with pain ranging from 2 to 6 (mean: 5). The survivorship analysis curve showed 67.5 +/- 19.5 per cent survival for all osteotomies to the interval of 9-10 years. There were 3 types of results: -3 early failures (4.6 per cent) one because of a deep infection, -in 7 cases, after a short initial functional improvement, there was a progressive degradation leading to failure in 3.7 years (2 to 6 years), -55 cases with a lasting period of functional improvement, 26 osteotomies leading to failure in 3.5 to 15 postoperative years and, 29 cases having reached the follow-up (7 to 16 years mean 10 years). There was radiographic improvement of the osteoarthritis increasing the joint space in 59 cases (90.7 per cent). There was no radiographic improvement in the 6 other cases, including the 2 functional failures. The functional degradation appeared parallel to the radiographic degradation leading to a decrease of joint space to 90 per cent. We tested differences between various groups using Log Rank test. We found no difference in survival between the 3 different types of osteotomy.

DISCUSSION

The results of this study can help to choose between intertrochanteric osteotomy and THA in the case of severe osteoarthritis. The best functional result of the osteotomy is in one postoperative year, with a mean MDA score of 15 and a mean pain score of 5. It appears that we do not predict the duration of functional improvement, the patient has 2/3 chances that this improvement reaches 10 years.