Wen P, Zhang Y, Hao L, et al. - In this analysis, the biomechanical influence of necrosis area on the collapse of the femoral head by finite element analysis was explored. Researcher obtained CT and MRI data from the hip joint of a healthy volunteer to develop a finite element (FE) model of a normal hip. Subsequently, the normal model and computer software according to China-Japan Friendship Hospital (CJFH) classification for ONFH was applied to develop five categories of osteonecrosis FE models. They examined collapse indices of each model by FE method, involving the displacement, peak von Mises stress and stress index of the simulated necrotic area as well as the lateral pillar contact area of the femoral head to acetabular. Compared with those of type M, C, and L1, the study found that the collapse indices of the femoral heads of type L2 and L3 FE models were significantly higher. In addition, different areas of necrosis result in varied effect on the femoral head collapse.