Biomechanics for Trabecular Architecture and Fracture Mechanism of Osteoporotic Cancellous Bone

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Osteoporosis decreases a bone density and makes it easy to cause fracture of bones. Bone density is a so-called isotropic varriable. Therefore, bone density can not present a difference of strength that depends on a distinction of anisotropy of the architecture.The femoral neck fracture occurs by force with various directions and intensity. In spite of this, the neck fracture type is limited to 2 kinds of in the typical and the crescent fracture type. This reason is a cause that osteoporosis changes a trabecular architecture (size and shapes of the cell structures). Simultaneously, we compared compression ultimate strengh and the histomorphometric parameters of the lateral, the principal compressive group and the medial cancellous bone in the femoral heads. Then we explained the fracture mechanisms which osteoporosis induces the typical fracture type of the intracapsular femoral neck fracture. Other hand, also we measured the bone mineral density (BMD) of the lumbar veretebrae and the every part in the proximal femur of osteoporosis patients by the DEXA.We analyzed correlation between BMD and the mechanical strength of the cancellous bone that were obtained through the experiment. As a result, it understood as long as we judges with only BMD,even we point out a tendency toward osteoporosis, it is impossible to predict a fracture while designating a place like a femoral neck and a vertebral body.A degree of anisotropy of the cancellous bone is possible estimation from the simple X-rays images by way of computer image processing. So we will be able to construct a prevention diagnosis system of bone fractures by judging and integrating the accumulation result of the mechanical properties which come from BMD and the anisotropy of the cancellous structures.