Successful orthotopic free autogenous joint grafts in the dog

Thirty free autogenous metacarpal and 26 phalangeal articular cartilages were transplanted in the forefoot of dogs. The graft in each case included the articular surface and a minimal amount of supporting subchondral bone. The majority of the metacarpal grafts retained a normal gross, microscopic, and radioautographic appearance, some for up to 1 year after transplantation. In contradistinction, all of the phalangeal grafts failed, probably because their flatt surface made it impossible to maintain adequate fixation to the host bed. As a result the majority of these grafts became displaced. Analysis of the incorporation of the metacarpal grafts into the host bed showed that this occurred when there was no significant period during which the articular cartilage was without subchondral support. The situation is different in the case of joint grafts with a larger amount of subchondral bone. In these, during the time that this necrotic bone is being resorbed and replaced by normal viable bone, the articular cartilage has extremely limited subchondral support.