[Experimental studies of osteochondral allografts].

It is important to know the possibilities of allogenic transplantation of the joint in the present modes of the artificial joint replacement. In order to clarify the fate of osteochondral allograft, an experimental study of fresh "shell" transplantation was made on the femoral head of the dogs. Fifteen adult mongrels, around 15 kg in weight, were used as a recipient, and the same number as a donor. Special instruments of the same sized male and female reamer were made to cut an osteochondral shell with 2 to 4 mm thickness. Transplanted animals were killed at the interval from 2 weeks to 3 years. Femoral heads from the transplanted side and the opposite side for control were observed by histo-morphometric techniques. Usual decalcified sections were stained with H-E and safranin-O to observe the articular cartilage, and undecalcified ground specimens were made to understand the remodeling of the subchondral bone. The underlying subchondral bone was completely remodeled by 1 year, the grafted shells were well adapted and fixed to the host bone. Although a number of cartilage cells on the superficial layer were decreased from an early stage, the whole articular cartilage could possess its original thickness and well functioned for three years. However, in some animals, the pannus formation and chondrolytic reaction which is thought to be an immunological rejection were observed at the margin of the grafted articular cartilage. This experiment has demonstrated that allogenic osteochondral graft with 2 to 4 mm thickness was very successful even on the femoral head, and clinical trials might be expected if the histocompatibility of the tissue is settled.