We experienced two cases of synovial osteochondromatosis of the hip.
Case 1, a 12-year old boy complained of limitation in his right hip motion. Roentgenograms showed many small calcified or ossified particles in the right hip joint. We performed synovectomy, and found the hip joint to be filled with more than two hundred calcified loose bodies. Range of motion of the hip recovered after surgery. Microscopic examination, revealed the synovium to have an osseous and cartilaginous lesion.
Case 2, a 24-year-old man complained of right coxalgia and limitation of right hip motion since he was 20 years old. Roentgenograms showed right hip joint space narrowing and osteoporosis. Hip tuberculosis or pigmented villonodular synovitis was Suspected. However, gadolinium (Gd) enhanced MRI with fat suppression showed enhanced hypertrophic synovium and no enhanced nodular lesion in the synovium. Therefore, this case was diagnosed as synovial oeteochondromatosis of the hip joint. Synovectomy revealed hypertrophy of the synovium, and osteochondromatosis were seen matted within the synovium. There were no loose bodies in the joint space. However, this case achieved only a small improvement in his range of motion post-operatively. Microscopic examination, the synovium had many cartilaginous lesions, but there was few ossiferous lesion.
We consider that Gd enhanced MRI with fat suppression is useful for the early diagnosis of synovial osteochondromatosis that has not been ossified.