Abstract
Two cases of osteochondromatosis have been presented. Roentgenograms of the cases showed many calcified loose bodies in the joint and atrophy of bone. Loose bodies were attached by pedicles to the synovial membrane which was in the form of a papillary fold. The articular surface was normal. In the pathological study, the peripheral layer of the loose bodies was generally fibrous connective tissue, in which some part of the synovial membrane remained. Its interior was composed of fibrous, hyaline cartilage. The central areas showed new bone-like formation and degeneration of the cartilage cells. The etiology of osteochondromatosis is unknown. Several theories have been advanced in an attempt to account for the metaplasia of the synovial membrane. In one case of the subject there was a history of trauma of the right hip joint, in the other case the patient had suffered from chronic arthritis of the left knee joint.
In addition to its predisposition toward neoplasma, osteochondromatosis may develop after trauma or chronic arthritis.
