Based on the CT data, a medical treatment FE model of hip joint prosthesis with stepped stem was rebuilt according the anatomy of the hip joint. Under the loads of 1.5 times standard body weight (70kg), the mechanical behavior of the treatment model was calculated, and the influence of step structure and distribution for stepped stem on femur stress and stability of total hip replacement were analyzed by three-dimensional finite element analysis (3D-FEA). The results show that the step structure changs the bone stress transmission on the interface of stepped stem and femur, and benefits to reduce stress-shielding in the femur. For the same distribution of step, the reduction of stress-shielding for raised stepped stem is better than that for concave stepped stem. The raised stepped stem of which the steps is distributed one of third part of the stem is of the best effect of reduction of stress shielding in all of the analysis models, and is a beneficial mechanical design to relieves osteoporosis or osteopenia of femur caused by stress-shielding and improve the reliability of it in clinic.
Adult ; Arthroplasty, Replacement, Hip ; methods ; Biomechanical Phenomena ; Computer Simulation ; Equipment Failure Analysis ; Finite Element Analysis ; Hip Prosthesis ; Humans ; Imaging, Three-Dimensional ; Male ; Models, Biological ; Prosthesis Design ; Stress, Mechanical ; Tomography, Spiral Computed ; Weight-Bearing ; physiology