軟骨移植についての実験的研究

抄録

Plastic and reconstructive surgery of the facial structures often requires the use of hard grafting materials to serve as supporting structures or to produce elevations of the skin surface. Among such grafting materials, autogenous cartilage grafts are probably the most widely employed. because of their obvious advantages. Autografting of cartilage, however, may not always be successful due to such factors as infection of the recipient site, the general condition of the patient, the condition of the graft, mechanical stimulation at the site of the graft, exposure of the graft, or when removed cartilage pieces are reinserted, and autografting also subjects the patient to the additional stress of obtaining the graft from other parts of the body. Actually, such conditions are interrelated and manifested in a complicated fashion in most instances. As. very few detailed studies of the effects of the condition of the implanted cartilage have been made, an experimental study of the effects of mechanical stimulation of the grafted site and exposure of the cartilage graft was undertaken in rabbits.
The experimental autografts, taken from the costal cartilage and the auricular cartilage of rabbits, weighing about 2 kilograms each, were mostly transplanted to the most frequent site of implantation of such grafts in clinical cases; that is, below the periosteum of the nose. To observe the effects of active mechanical irritation of the grafted cartilage, the back of the animal. under the skin was also selected for the recipient site.
As cartilage for grafts are usually shaped into different forms according to the purpose for which they are used, the experimental grafts were also shaped into various simple forms to observe the relation between the shape of the graft and its eventual condition. Auricular cartilage grafts were also implanted in the bone to investigate the reactions between the bone and cartilage. In all the experiments cartilage autografts with and without perichondrium were used.
The effects of mechanical irritation were studied by transplanting costal cartilage autografts. to the subcutaneous tissue of the back and auricular cartilage autografts below the dorsum of the nose subperiosteally. After varying periods the regions of the implanted grafts were massaged with the fingers for a period of one week. Rapid absorption of the cartilage grafts. occurred the earlier the mechanical irritation was started after the operation, but rapid absorption could be prevented by waiting for about two weeks before commencing massage of thegrafted area. The auricular cartilage autografts transplanted subperiosteally under the dorsum of the nose appeared to be more pronouncedly affected by the mechanical irritation than the costal cartilage autografts placed under the skin of the back of the animals.
The effects of exposure of the cartilage grafts after transplantation were studied with both costal and auricular cartilage, which were implanted subperiosteally below the dorsum of the nose and then partially exposed after varying periods. Removal of the grafts one week after exposure revealed degenerative changes marked by necrosis of the exposed surfaces of the grafts. in practically all of the specimens. The auricular catilage grafts, in particular, had become separated from the recipient bed, showing necrotic changes of both surfaces, and there was a tendency for the exposed recipient sites to be covered by growth of skin from the edges. Late exposure of the implanted cartilage produced stronger degenerative changes than when the graft was exposed in an earlier period. In the event of exposure of the grafted cartilage in actual clinical cases, therefore, immediate covering of the exposed surface with skin or other tissue that will provide nourishment and sufficient pressure to assure close contact of the graft to the recipient site are advisable.