Ein Materialgesetz zur Beschreibung des Alterungsprozesses kortikaler Knochen

Abstract

Healthy bone is constantly being remodelled. This leads, especially at advanged ages, to a decreasing specific strain energy at fracture, and, simultaneously,a decrease of the cross section. This causes a increasing risk of fracture. Osteoporosis is a systematic bone disease, which accelerate these processes dramatically.In this paper a simple damage model is developed, which is able to differentiate between the natural aging process and the osteoporotic loss and damge of bone. The secant modulus of dead bone in bending is calculated, unsing published data of 46 people on both sexes and different ages. Using histological measurements, the damage parameters of the homogenised microstructure as well as existing microcracks and their growth are identified. The individual mechanical parameter of living patients are found by multiple linear regression of the histological measurement, which can be obtained from a minimal invasive biopsy. If the calculated individual stress-strain curve plotted against the measured cross section, the individual fracture load can be predicted. By comparing this loading with the average, age-related loading, the fracture risk of patients can be specified as an indication for osteoporosis.