Operative treatment of primary synovial osteochondromatosis of the hip.

BACKGROUND Primary synovial osteochondromatosis of the hip, a rare benign condition characterized by multiple intra-articular osteochondral loose bodies and synovial hyperplasia, may result in mechanical symptoms and degenerative arthritis if untreated. The purpose of this study was to report the results of arthrotomy alone or combined with anterior dislocation of the hip to perform synovectomy and removal of loose bodies in patients with this condition. METHODS We retrospectively reviewed a consecutive series of twenty-one patients (twenty-one hips) with primary synovial osteochondromatosis of the hip treated with open surgical débridement. On the basis of the extent of extra-articular involvement as seen on preoperative magnetic resonance imaging, eight of the twenty-one patients underwent synovectomy and removal of loose bodies following anterior dislocation of the hip and thirteen underwent the same procedure with arthrotomy alone. At a mean of 4.4 years postoperatively, the patients were assessed clinically and radiographically with special attention to disease recurrence, osteoarthritis progression, and surgical complications. RESULTS The mean Harris hip score for the entire series of patients improved from 58 points preoperatively to 91 points at the time of the latest follow-up. Eighteen of the twenty-one patients had a good or excellent clinical result, and seventeen patients were satisfied with the result of the surgery. The clinical scores, patient satisfaction scores, and radiographic grades of osteoarthritis at the time of the latest follow-up did not differ significantly between the group treated with dislocation and the group treated without dislocation. Symptomatic disease recurred in two of the thirteen hips treated with arthrotomy alone and in none of the hips that had undergone dislocation. However, the surgical complication rate was higher in the group treated with dislocation than it was in the group treated without dislocation (p = 0.042). While patients with some signs of mild osteoarthritis at the initial procedure had a higher rate of osteoarthritis progression, severe osteoarthritis requiring arthroplasty had developed in only one patient at the time of follow-up. CONCLUSIONS At a mean of 4.4 years postoperatively, we found that open synovectomy and removal of loose bodies for the treatment of primary synovial osteochondromatosis of the hip is a reliable procedure that can effectively relieve symptoms. Our results also indicated that synovial osteochondromatosis may recur in patients with extensive involvement who are treated with synovectomy alone without dislocation of the hip; however, surgical complications are more likely to occur in patients managed with anterior dislocation of the hip and synovectomy.