Several Researches Of Physical Problem In Osteoporosis

Osteoporosis is one of the most common diseases among the old people, which the risk of fractures is increased along with decreasing of bone masses and changing of micro-construct, however, the fracture in patients with osteoporosis may have concern with the quantities and masses of bone. This paper aims at the physical problem in osteoporosis to serve for clinic, which is correlated with the biomechanical simulation of cancellous bone, diagnosis method and standard, biophysical treatment. Some of the results are compared with that obtained from experiments to explain the clinical phenomenon as well as to provide physical proof and direction for clinical appliance. Main studies are show below:1. The material mechanical characteristics of cancellous bone are depended on its microstructure. The volume fraction ratio of cancellous bone is an important parameter in all characteristics describing microstructure. Appearance density of cancellous bone can be predicted from the volume fraction ratio because there existed a strong positive correlation between the appearance density and volume fraction ratio. After finishing the pathology slice, a two-dimension histogram segment method has employed to determine the distribution characteristics of the volume fraction ratio. We find that the cancellous bone volume fraction ratio is gradually increased along the axial direction of femur and approaching to the compact bone, but almost constant along the transversal direction. Cancellous bone is modeled as atransversely isotropic, liquid saturated porous solid. The two-dimension histogram segment method can be used to relatively determine the distribution characteristics of cancellous bone ratio from different directions. The distribution characteristics can provide experiment dates for mechanical simulation of cancellous bone.2. Using homogenization theory to predict mechanical properties of bone is a worth job, which is only in its beginning. In this chapter, the homogenization method of predicting composite material macro elastic modulus is introduced in detail. The homogenization is one mathematic method with strict theory base. Using the homogenization method, the relationship between the microstructure and the composite macro properties can be formed. Two models are proposed to simulate the microstructure of trabecular bones, and the homogenization theory and finite element method are employed to calculate the macro-equivalent Young' s modulus of trabecular bone. The macro-equivalent Young' s modulus of different trabecular bones simulated by two cell models and their relations to the volume fraction ratio(VFR) of bone materials are computed and compared to the experimental date given in literatures. It is also discussed how to apply the cell models in different trabecular bones. The results show that the methods and two cell models proposed in this paper can simulate microstructures of trabecular bones and compute material.3. Prevention of osteoporotic bone fractures requires accurate diagnostic methods to detect the increase in bone fragility at an early stage of osteoporosis. However, today's bone fracture risk prediction, primarily based on bone density measurement, is not sufficiently precise. In this chapter, we investigate the relationship between BMD, VBMD and vertebral compressive intensity. BMD, BMC, AREA, HEIGHT of 8 cadavericvertebral spines were evaluated with DEXA and be separated into individual vertebral bodies. The volumes of vertebral bodies were measured and the values of VBMD were calculated. According to their BMD, all vertebral bodies were divided into 3 groups: normal group; osteoporotic group and serious osteoporotic group. The strengths and stiffness of those vertebral bodies were measured, it was suggested that the axial compression strength and stiffness were correlated to BMD and VBMD, especially related to VBMD. The VBMD was a significant value to diagnosis osteoporosis in clinic.4. There is increasing evidence that, in addition to bone density, also the bone micro-architecture...