A model of transplantation of a joint surface, that is, the patella, was studied in rabbits. The fate of the various components of this composite graft was compared in autografts and homografts in unsensitized and sensitized animals and in homografts in animals treated with an immunosuppressive agent. The effects of immobilization alone were noted and the changes occurring from two weeks to one year were evaluated. In general the articular cartilage fared well regardless of the genetic relationship of host and donor or the immune status of the host. A major technical difficulty lay in faults of healing of the soft tissues leading to joint-surface malalignment which adversely influenced the fate of the transplant. Suggestions are offered to reduce the incidence of this complication but in future applications of the model technical failures should not be included in end-result evaluation.

A self-limited but intense soft-tissue infiltration with inflammatory cells occurred in the unmodified homografts. Revascularization of the bone nucleus was also considerably delayed in these animals. Drug-induced immunosuppression favorably affected both the soft-tissue reaction and the rate of revascularization. These findings are discussed in the light of present clinical needs and current knowledge of the immune response to cartilage homografts.