[Effect of aging on compressive strength of lumbar trabecular bone in hemodialyzed and non-hemodialyzed patients].

In order to clarify the effect of aging and bone mineral content on the compressive strength of lumbar trabecular bone, the third lumbar vertebral body (L3) was analyzed by mechanical and chemical tests in hemodialyzed (HD) and non-hemodialyzed (non-HD) patients. L3 was removed from 40 non-HD patients and 10 HD patients at autopsy. Cylindrical trabecular bone samples from L3 were analyzed by compression test, relaxation test and Brinel's test. Bone mineral content was based on Ca, P and Mg measured after incineration of the samples. In non-HD patients, a significant age-related decrease was observed in both Brinel's hardness (HBS) (r = -0.470) and Young's modulus (Qo) (r = -0.527), and there was a significant increase in age and viscoelasticity (B) (r = 0.439). HBS and Qo in about 50 percent of HD patients were larger than those in non-HD patients. C-PTH in HD patients showed a significant positive correlation with HBS and with Qo. Bone Ca content of the 50-69-year-old non-HD patients was 81 percent of that in the patients in their 40s and the content in the patients aged over 70 years was 55.5 percent of that in the patients in their 40s. In non-HD patients, the P/Ca and Mg/Ca weight ratios of bone were nearly constant regardless of age or sex. However, bone P/Ca and Mg/Ca weight ratios were relatively large in 80 percent of the HD patients. Bone Ca content exhibited a significant positive correlation with HBS (r = 0.399) and with bone mineral density measured by quantitative computed tomography (QCT) (r = 0.819). In conclusion, it was indicated that bone mineral content and compressive strength of trabecular bone decreased with aging, and that biomechanical competence in HD patients was much more prominent along with elevated C-PTH.