Joint space widening in synovial chondromatosis of the hip.

BACKGROUND

One of the radiographic findings in synovial chondromatosis of the hip is widening of the joint space between the femoral head and the acetabulum, although the cause and sequelae of the widening are unclear.

METHODS

Between May 1991 and June 2005, twenty-one patients with synovial chondromatosis of the hip were treated with open synovectomy and removal of osteochondral fragments. Joint space widening was assessed on radiographs made preoperatively, immediately after surgery, and at the time of follow-up. The changes of the radiographic joint space width were evaluated during the mean follow-up period of 5.9 years (range, 2.3 to 12.3 years).

RESULTS

Twelve patients had joint space widening on preoperative radiographs of the hip. Medial joint space widening was seen in three patients, and both medial and superior joint space widening was evident in nine patients. Compared with the medial and superior joint spaces in the unaffected, contralateral hip, those in the affected hip were wider by an average of 44.7% and 35.9%, respectively. The medial joint space widths of the affected hip decreased slightly during the early postoperative period; however, widened joint spaces were persistent at the final follow-up visit, without other important changes. The superior joint space widths did not show substantial changes throughout the postoperative follow-up period.

CONCLUSIONS

Joint space widening is a recognized radiographic finding in primary synovial chondromatosis of the hip. Although there was persistence of joint space widening after synovectomy in all patients, this joint space widening did not influence the clinical results at the time of follow-up.