Neglected synovial osteochondromatosis of the elbow: a rare case

BACKGROUND Synovial osteochondromatosis is a benign metaplastic proliferative disorder of the synovium characterised by the formation of multiple cartilaginous nodules in the synovium, many of which detach and become loose bodies. The disease is characteristically monoarticular, most commonly involving the knee. A site in the elbow was first reported in 1918 by Henderson, but any joint may be involved. Very few cases of synovial osteochondromatosis of the elbow have been reported in the literature. The presenting symptoms are usually diffuse discomfort in the affected joint and decreased range of motion with an accompanying gritty or locking sensation. The treatment of choice is excision of the synovium and removal of the loose bodies. CASE PRESENTATION We report a rare neglected case covering a 32-year period of a locally aggressive synovial osteochondromatosis of the elbow in a 47-year-old man. Clinical examination revealed a significant increase in size of the left elbow compared to the contralateral one. The simple radiographs and the computed tomography showed multiple rounded, calcified bodies widespread throughout the elbow joint. At surgery we removed and counted a total of 312 loose bodies, varying in size from a few millimeters to 3 cm. The evaluation at 6 months postoperatively showed marked reduction in the volume of the elbow, improvement of extension and flexion and an increase of the Mayo elbow performance score from 50 points before surgery to 80 points at 6 months postoperative. CONCLUSION Synovial osteochondromatosis is an uncommon condition characterized by the formation of multiple nodules of hyaline cartilage within the sub-synovial connective tissue. The differential diagnosis includes chronic articular infection, osteoarthritis, pigmented villonodular synovitis, mono-articular inflammatory arthritis and periarticular neoplasms like synovial sarcoma. The treatment of choice is excision of the synovium and removal of the loose bodies. The prognosis is good, but recurrences may occur if the removal is incomplete.