Some of the cells in autogenous whole joints remain viable following transplantation. The bone is rapidly revascularized and the dead bone is replaced with new bone. The deeper layers of cartilage cells remain viable, but some degeneration of the articular surface usually results.
All of the cells in delayed homogenous transplants and most of the cells in direct homogenous whole-joint transplants die. Revascularization and active osteogenesis are slow. The grafts unite and function satisfactorily for six to eight months, but degenerative changes similar to those seen in aseptic necrosis begin between four and six months after transplantation. These changes may progress to complete disintegration of the joint.
Since similar changes occur in direct homogenous transplants as in delayed homogenous transplants, the method of preservation apparently is not the important factor in the early degenerative changes. The factor that produces these degenerative changes, which are so much greater than those in autogenous whole-joint transplants, has not been determined but is probably related to a type-specific physicochemical structure of bone.
The writer has had no experience in using whole-joint transfers clinically, but from the experimental data at hand he believes that one could expect satisfactory results from autogenous transfers, particularly in non-weight-bearing joints, such as the small joints of the hand. Homogenous joint transplants, direct or delayed, heal satisfactorily, unite to the host bone, and are technically feasible. Possibly in non-weight-bearing joints, with good cooperation by the patient, satisfactory clinical results might be obtained. In most instances, however, and particularly in weight-bearing joints, long-term good results are not to be expected at present. It is hoped that further investigative work will reveal methods of accurately matching bone types and thus make such massive homogenous transfers as entire joints acceptable.