大腿骨にみられる身体運動抑制の影響

―下腿を切断した高齢男性の一例―

抄録

Human femora obtained from a cadaver of a 70-year-old man were examined by means of bone histometry, image-analysis on X-ray radiographs and a mechanical strength test in order to investigate the effects of disuse on the femora. The patient had been bedfast for seven months until his death because of an amputation of the left lower leg due to a diabetic intractable ulcer on the foot caused by a burn. Other detail records of the medical and the life-style history were also examined.
A marked atrophy of the muscles of the hip and thigh was observed on the amputated side. The macroscopic shape and proportion of the femora were not significantly different between both sides. The results of bending strength test at the mid shaft, disclosed a marked mechanical fragility on the amputated side. The cortical bone area in the shaft showed no significant difference between both sides. However, the degree of bone loss was more pronounced at the anterior region of both shafts. The trabecular bone at the femoral head showed a marked atrophy on the amputated side, especially at the principal compressive group of the trabecular bone. This atrophy was thought to be due to the absence of the compressive stress because of the disuse caused by the amputation. A trabecular bone atrophy was also observed on the normal side and its degree of atrophy was greater than that of agematched values. The multiple systemic factors such as the diabetes and the bedfast condition might had influenced on the bone metabolism in this case, therefore the careful examination of the systemic conditions was required to disclose the effects of local mechanical conditions on the bone metabolism.