Surgery of a Rare Case of Multiple Synovial Osteochondromatosis of the Hip Joint.

INTRODUCTION: Primary synovial osteochondromatosis of the hip is a benign disorder, which is not frequently seen clinically. The characteristic of this disease is proliferation of synovium and formation of loose bodies inside the joint. It is known that only the loose bodies derived from synovium were called synovial osteochondromatosis. Although it can take place in any joint, the knee is most commonly affected, involvement of the hip joint is relatively rare. We report a young man who has multiple synovial osteochondromatosis in his left hip.

CASE REPORT: A 21-year-old young man, who had progressive pain and functional impairment of his left hip, came to our hospital. He complained that 2 years ago, he began to feel painful of his left hip joint when walking and squatting. Physical examination found that the motion range of the hip was obviously limited, with internal rotation, abduction in particular. The Harris hip score was just 38 points. X-ray shew multiple osteochondromatosis with mild degenerative osteoarthritis existing inside the hip joint. Magnetic resonance imaging shew that the synovial osteochondromatosis intersperse inside the hip joint. During the operation, posterolateral incision of the hip was chosen with dislocation of the femoral head for total exposure of the hip joint to debride extensive loose bodies and proliferative synovial tissue. Pulse irrigation was applied to flush out the residuals. More than 872 of osteochondromatosis were removed out of the hip joint (some small ones were sucked during the operation). The size of the loose bodies ranged from 3 cm × 3 cm × 2.5 cm to 0.2 cm × 0.2 cm × 0.15 cm. Post-operation radiography shew most pathological tissues were taken out. After the operation, the patient rehabilitated fast. The pain relieved and he could bear weight and walked 3 days postoperatively. 1 and 3 months postoperatively, the patient came to us for visit, and he said that he just had a relatively satisfactory function of his affected hip. He could walk, slowly run, and squat freely. But sometimes he could feel a bit painful on his left hip joint after long walking and fatigue. And sometimes he could feel and hear mild crepitus on the left hip joint. 12 months later, the patient came again and complained that the pain of his operated hip became a bit more serious than before since about 20 days ago. The range (internal rotation, abduction in particular) of this hip joint could not live up to normal, compared with the uninvolved hip in physical examination. X-ray shew osteoarthritis had become a bit severer. The patient accepted the suggestion of prospective total hip replacement.

CONCLUSION: Multiple synovial osteochondromatosis is not a very uncommon condition. However, there may be unusual presentations. It can take place in any joint, the knee is most commonly affected, however, involvement of the hip joint is relatively rare as was seen in our patient.