Stress adaptation in femoral bone is an important indicator to predict bone behavior and remodeling after arthroplasty, computationally. Presence of prosthesis stem in the affected limb has created mismatching materials in the femoral shaft which alters the load distribution. The changes are not only reflected on the operated limb but also to the non-operated limb as well. In this study, biomechanical evaluations of the lower limbs were established using the finite element method. Bone adaptation was predicted computationally for both limbs on the resulting principal stress and bone mineral density to predict the stress shielding and bone remodeling phenomenon. Computed tomography (CT-based) images of a 79-years old female patient with hip osteoarthritis were used in developing the three dimensional inhomogeneous lower limb model. Then, the affected hip joint was cut off and replaced with total hip artroplasty (THA) which consists of acetabular cup, liner, femoral ball and prosthesis stem. A distributed load of 60kg was applied in the cross sectional region of lumbar vertebra and totally fixed at the distal end of the limbs to present a quiet standing position. Results showed that the stress adaptation was predicted at both the operated and non-operated limb in THA model. The proximal region of the operated limb indicated the highest stress changes which lead to bone resorption while the distal region had a possibility of bone thickening. Findings of bone remodeling analysis also estimated high changes of bone mineral density in the operating limb over 5 years.
Keywords: lower limbs, total hip arthroplasty, stress adaptation, bone remodeling, finite element analysis