Design And Biomechanics Analysis Of Several Individual Prosthesis

Femur is the important load-bearing structure of human,it has the important responsibility to bear upper body weight and running and sports. However,the influence of external forces and disease often lead the upper femur segment irreversible lesions. Total hip replacement is one of the way to restore upper femur function. The word's population is more than 6 billion,there will be more 0.5 million patients choose total hip replacement.The implanted effect of artificial femoral stem is closely linked to their exposure mechanical environment and the stem's force conditions were impacted by the stem form. Currently used in clinical with the common shape and were selected by experience. The doctor didn't consider the bone mechanical properties of patient effect to the prostheses after total hip replacement. This article is to carry out studies on this problem.Because most femoral stems in Chinese clinical were imported from abroad in particular USA products,so we should check the bone mineral density of China and America to juxtapose. It is found that compared American average BMD and Chinese people BMD the maximum difference is 40%,lower limitation is 30%. The difference rate of BMD mainly distribute in the range of 20 percent. So we should choose the centralized area value for calculation.Three-dimensional finite element model with two materials properties of femur was established,four prostheses model was designed and was compared with a popular prostheses on the market. It is found that the different prostheses design need different BMD and have the different effects on femur with different BMD. Prostheses adaptability was different according to the different judgment of prostheses.After the finite analysis the style 1 model was discarded because it cause an excessive stress in the proximal femur. It is found that different criterion will correspond to different prostheses. When using stress or strain as the criterion the style 4 model is suitable the BMD in the range of 0.69-0.77 g/cm3 in the area of the greater trochanter of femur. When using strain energy as the criterion,style 2 model is suitable the BMD in the range of 0.780-0.862 g/cm3 in the area of the greater trochanter of femur. When using strain energy density as the criterion,style 3 model is suitable the BMD in the range of 0.657-0.780 g/cm3 and 0.862-0.985 g/cm3 in the area of the greater trochanter of femur. Therefore the prostheses selection and design should be fully aware of the prostheses geometry effects by BMD. As many consider mechanical criterion of prostheses.