In thirty cases of synovial osteochondromatosis studied clinically and
pathologically, the process appeared to follow a temporal sequence
characterized by three recognizable phases (1) active intrasynovial disease
only, with no loose bodies; (2) transitional lesions with both active
intrasynovial proliferation and free loose bodies; and (3) multiple free
osteochondral bodies with no demonstrable intrasynovial disease. If gross
examination at the time of surgery shows that the disease is in the third
phase, it would appear that synovectomy may not be necessary. However,
extrasynovial intra-articular cartilaginous lesions may persist after
synovectomy in the other two phases and may grow, causing recurrence of
clinical symptoms in the absence of new intrasynovial disease.