Response Analysis of Bone Mass of Proximal Femur to Surface Replacement of Hip Joint

Total hip joint replacement is the prevailing surgical treatment of painful joint diseases. In classical THR, both parts of the joint (acetabulum and femoral head) are replaced by prosthesis. Classic THR gives good results as regards the relief of pain and improved mobility of elderly patients (over 65 years). Problematic is the application of the replacement in younger and active patients. Surface replacement has been proposed as one of the possibilities of preventing THR. The correct function of hip joint implant is associated also with correct function of bone mass, where is placed. Therefore the aim of this article is stress-strain analysis of two hip joint variant with stochastic material data properties of computational model. From the output of CT scanner model of geometry were created. Cancellous bone of proximal femur was divided into the 18 regions where were bone modelled by isotropic, linear and elastic model. Material properties were known from literature. Whole model was loaded by force, corresponding to load by standing on one leg. Values of Youngs modulus were assumed by normal distribution in each region. The problem was solved in the ANSYS program system. Stochastic analysis was done with OptiSLang software. From stress-strain analysis of two variants a few points of proximal femur (physiological and resurfaced hip) were picked for stochastic analysis. These points were characterized by maximal and minimal principal stress and by Von misses stress. Thanks to this work we can describe: loading in each region of bone mass, variations of stresses in each points of geometry and sensitivity of input data (material properties, loading) to output data (strain-stress).