Vascularized osteochondral allografts in a canine model.

The aims of this paper, carried out in dogs, are to develop the surgical techniques involved in transplantation of the knee, and to study the effects of the immunosuppressnat drugs, cyclosporin, on the fate of allografts taken from unrelated animals. The survival and structure of the grafts were evaluated by serial radiological examinations and radioactive bone scans and by repeated biopsy. The growth of donor and recipient bones were assessed by tetracycline labelling and their structure and viability by histological examination. In vascularized autografts as a pilot study, three months after operation, 4 animals showed apparently normal joints and only minor atrophy of their thigh muscles. By contrast all 3 dogs with allografts rejected the graft within the first 5 days had to be sacrified. In the final group, 3 dogs were given vascularized allogtafts and administration of cyclosporin started at the time of operation and continued for 3 months. At 3 months after grafting, all dogs showed bony union and a constant and active uptake of radioactive tracer in the graft. Histologically, the grafts showed viable chondrocytes and osteocytes, and active turn-over of the bone until withdrawl of cyclosporin. After withdrawl of cyclosporin, the grafts were rejected rapidly.