Recent advance in the transplantation of human organs are widely applied in many fields, despite little progress was made in orthopedic surgery in the bone and joint transplantation. Experimental studies on bone or joint transplantation have been reported enormously with variable results. Many authors used only small part of cartilage, epiphyseal plate or osteochondral graft and some authors studied the fate of massive autogenous and homogenous bone graft including articular surfaces, but few workers have reported on transplantation of whole bone including articular cartilage, epiphyseal plate, cancellous and cortical bone, and compared the result with autograft and fresh and frozen homograft.
This expermient was undertaken for the study of autogenous, and fresh and deep-freezed homogenous transplantation of distal portion of femur including articular cartilage and epiphyseal plate in rabbits. The distal femur was exposed and completely freed of its soft tissue attachment and osteotomized at a one and half centimeter above the epiphyseal plate. Eighty young rabbits were divided into three groups: thirty for autograft, thirty for fresh homograft and twenty for deepfreezed homograft. The distal femur was replaced in situ in autograft and exchanged between two animals in fresh homograft. In group of deep-freezed homograft, the distal femur which was stored at -20 degrees centigrade for two weeks before it was replaced in a rabbit of similar weight. These animals were sacrificed at intervals varying from one to twelve weeks and longitudinal section of distal half of femurs were prepared for histological examination, and the results were observed as follows.
1. In the autograft, the articular cartilage retained normal appearance except for reduced stain-ability of the chondrocytes until eight weeks, and early fibrillary degeneration appeared in the periphery in twelve weeks. In the fresh and deep-freezed homograft, almost similar findings were observed, which suggest the articular cartilage were rather resistive to immune reaction.
2. The epiphyseal plate continued normal growth in early stages in all groups, but in fresh homograft, the germinal cell layer underwent necrosis in four weeks and eventually fused in twelve weeks, In deep-freezed homograft, normal growth continued until eight weeks and partially fused in twel~~e weeks, which findings are not much different from autograft.
3 In autograft, solid bony union at grafted site was obtained in eight weeks, and in fresh homograft, satisfactory union process continued until four weeks and then gradually delayed in healing with some necrosis at twelve weeks. In deep-freezed homograft, very little difference in the timing and character of the union was noted from autograft.
4. The satisfactory result in the growth at epiphyseal plate and in fracture healing in deepfreezed homograft are suggestive of deep-freezing may destroy the antigenicity of bone homograft.
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