[Problems concerning bone union influenced by heat generated in osteotomy (author's transl)].

The author experimentally investigated in rabbits how the heat generated by bone saws affected bone union in osteotomy. Radiographic and soft X-ray findings revealed that recovery of the lesion in every bone shaft after osteotomy was marked in all. However, the time required to obtain complete recovery of the lesion differed depending on the instruments used. That is to say, it required 3 weeks after surgery by means of Gigli's saw, 4 weeks by means of Stryker bone saw and lower speed bur (2,000 rpm) and 6 weeks by means of higher speed bur (18,000 rpm). Recovery of lesion by bone cut with each bone saw on the unscalded side was one or two weeks earlier than that in the scalded side. This was also proved on histopathological findings. With regard to the disappearance of osteocytes in the bone cortex at the cut surfaces of bones, micrometric findings revealed that there was a great difference between the scalded and the unscalded side in every group except in the group where a Gigli's saw was used. However, almost no difference was observed on the unscalded side among every bone saw. According to scanning electron microscopic findings at every surface cut with various bone saws, collagen fiber was preserved on the unscalded side where physiological saline solution was sprayed. Particularly, the collagen fiber appeared to be torn off in the case of lower speed bur (2,000 rpm), the cut surface was well uniform in the case of higher speed bur (18,000 rpm). Thus, I have learnt that we do not need to give much attention to the kind of instrument, if effort using physiological saline solution, are made to avoid the heat generated by bone saws when osteotomy is done.