Autogenous and homogenous transplants of articular cartilage and cancellous bone were performed on the knees of dogs. If the transplants did not exceed five millimeters in thickness and if they were subjected to physiological function, the transplanted articular cartilage, both autogenous and homogenous, was still viable 772 days after transplantation, as shown by gross and microscopic examination.

The cancellous bone in both types of transplant did not survive, but was subsequently gradually resorbed and replaced in a physiological manner by new appositional bone surrounding the transplanted bone without evidence of foreign-body reaction. In the cases examined it was clear that the host accepted the non-living bone trabeculae as a template surrounding the trabeculae with a layer of living bone, thus ensuring acceptance of the transplanted bone. The transplanted marrow died and was replaced first, by granulation tissue, and then, by marrow cells from the host.

Autogenous transplants of similar grafts to muscle and homogenous transplants to the knee with the graft countersunk below the joint surface were absorbed, thus indicating the importance of function in the survival of transplanted tissue.

Similar transplants in human beings have shown rather encouraging results but too few cases have been followed long enough to justify reporting these now.

It is concluded that the thickness of the transplant is critical and that unless the implant is subjected to the stimuli of normal physiological function it will not survive.