Stress shielding in uncemented hip implants: a study using finite element analysis

Abstract

<p>The finite element method and modeling has become very important in various simulations and analysis of orthopedic implants. Researchers are using this technique exclusively for stress simulations and fracture predictions. Hip implants show a considerable degree of stress shielding after significant amount of time after implantation. So, the aim of this study is to compare simulated stress analysis results for various hip implants which are commercially available. Dne of two type of prostheses (Le. uncemented) was being used for analysis. The results gave idea about the degree of stress shielding in various hip implants which lead to design optimization to avoid stress shielding. The total hip prosthesis must be securely attached within the skeleton for good function. There are two methods to secure the fixation of the total hip prosthesis to the skeleton. These methods are bone cement and cementless techniques. In the bone cement total hip technique, bone cement is used for fixation of the prosthesis to the skeleton. In the cementless technique, the total hip is directly fixed into the bed prepared in the skeleton. If the stem shape design leads to high stresses in fixation areas of the prosthesis, fracture in short term or fatigue failure in long term of the prosthesis quite likely occurs. This phenomena of generation of higher stresses after implantation is referred to as STRESS SHIELDING of hip implants. So, a computational study was performed using finite element analysis (FEA) of three dimensional solid hip implant models. Four different hip implant models were utilized to compare the von mises stress generated after simultaion. The parameters examined were the magnitude of von mises stress and the area having highest magnitude stress which should be accounted for during total hip implant design as well as in the practice of arthroplasties. A static analysis was performed for all 4 hip designs using CoCr alloy.</p><p>This presentation occurred at the Wright State University Campus-Wide Celebration of Research, Scholarship and Creative Activities on April 16, 2010</p>