The development of loose bodies in human joints.

Loose bodies in joints in 119 patients were analyzed histopathologically. A gradual growth in size and configuration of different specimens was due to surface proliferative changes of chondroblasts and osteoblasts. Cartilaginous layering was present in 86.6 per cent of the cases. Osseous layering was present in 79.8 per cent of the cases. Resorption within the new layers of cartilage and bone was manifested both by viable osteoclasts on the surfaces of many specimens and previously formed resorption cavities which had been refilled by the layering phenomenon. Refilled resorption cavities were present in 68.1 per cent of the cases while osteoclasts were observed in 49.6 per cent. It is proposed that osteoblastic and osteoclastic differentiation and function is not dependent upon a blood supply since the specimens from the 119 cases were free of any synovial attachments. Revascularization which occurred when free osteochondral bodies became reattached to the synovium was a distinct process that was differentiated from the accretion and resorption that was observed in the free specimens. Calcification occurred within the necrotic portions of both the nidus and deeper new layers of any particular specimen. Dystrophic calcification was observed histologically in 91.6 per cent of the cases.