[Arthroplasty of the hip after bone fusion. Report of 13 cases].

The authors have realized this surgical procedure upon 68 patients from 1978 to 1987. The fusion was badly tolerated or initiated a decompensation in the lumbar spine, in the knees, or in the opposite hip. This type of arthroplasty is difficult because the usual anatomical marks are changed and a pre-operative schedule is necessary to restore a satisfactory abductor strength. Special implants are needed to fit the frequent femoral dystrophies. 57 patients (62 hips) have been reviewed four to five years after operation. The functional improvement was important in the lumbar spine, not as much in the knees and in the opposite hip. The result upon the operated hip was satisfying for the mobility (average flexion: 78 degrees) and for the pain which disappeared apart from scarce complications. But, the stability was not as good with 20 per cent insufficiencies of the gluteus medius, implying for these patients the use of a walking-stick, the impossibility of standing on one leg, and the Trendelenburg sign. The state of the gluteus medius is the condition of a successful operation. The electromyogram performed before the operation may show a denervation; in this case, a choice must be done between an osteotomy of femoral correction and an arthroplasty implying a risk of instability which would be said to the patient.