It is now well recognized that many different complex factors are involved in the problems of joint reconstruction. This paper attempts to deal with only one of these factors, the machanism of the formation of a cartilaginous surface covering the bone ends within the joint.
This kind of process is seen in other tissues, such as bone, nerve and blood vessels. In the reconstitution of these tissues, transplants do not themselves proliferate to replace deficiencies. Rather do they behave as a matrix into which the specific cells of the host grow.
There is a possibility that cartilage implanted into a site of potential cartilage formation such as a joint may act in a somewhat similar way, determing the path of growth of host cartilage cells and moulding the shape of the resulting cartilage mass, while the implant itself undergoes gradual dissolution.
The hipp joint of rabbit was chosen to be subjected to weight bearing. 39 rabbits were used, and a standard technique of operation, post operative care, biopsy and histology was performed. In this
paper, in order to get 26 cartilage cups, 13 rabbits were sacrificed, then, under ether anaesthesia cartilage implantation had been done in 26 cases over the denuded femoral heads. After the operation a plaster was applied from pelvis to lower extremity.
Among 26 cases, 8 (30 per cent) has expired due to hemorrhage or shock. Remaining 18 cases were sacrificed 2 weeks, 3 weeks, 8 weeks, and 12 weeks following surgery, and obtained specimens to study in details. The results are as follows.
1) New reactive tissue, formed over the raw bony surface in the joint is transformed to cartilaginous tissue by the effects of, lack of vascularity, mechanical stress and strain due to. the .body._ weight, and gliding movement. The tissue is consists of mesenchymal cells or fibroblasts derived
from periosteum, endosteum, undifferentiated marrow cells, and synovial membrane.
2) The graft may stimulate potential cartilage forming tissue to proliferate mesenchymal cells and fibroblasts to be converted into cartilage. And it may mould the shape of the resulting cartilage mass.
3) The mesenchymal cells and fibroblasts infiltrated into the graft make metaplastic changes to the chondroblasts. On the other hand, the implanted graft is progressively invaded by cells and fibers, and undergoesgradua dissolution. The normal hyaline cartilage is located at the weight bearing portion, while a section taken from the non-weight-bearing portion shows increased fibrous tissue.
4) Degenerative changes in :its cells and matrix or inflammatory cellular response have not been observed, but in very early stage, as transitory manifestation, some blood cells are scattered around the surgical wound.
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