Porous Lattice Structure of Femoral Stem for Total Hip Arthroplasty

Abstract

Total Hip Arthroplasty (THA) is one of the most successful surgeries in trauma and orthopaedics providing pain relief and restoring the quality of life of young and elderly patients. Despite the advances of implant design to augment the effectiveness of the THA, problems have arisen since the life expectancy of a patient with a hip implant does not pair with that of the prosthesis. Current hip prostheses are mostly dense, and therefore, are stiffer by possessing a higher Young’s modulus. Continuous and cyclic loads originated from daily life activity may cause bone resorption and stress shielding thus provoking aseptic loosening, which in time leads to revision. A femoral stem featuring a porous lattice structure is proposed as design to allow bone ingrowth, reduce stiffness, transport and direct body loads. Three computational models were evaluated: 1) healthy femur, femur implanted with 2) commercial femoral stem, and 3) femoral stem with porous lattice structure. The load simulating a person standing in one foot was applied to the head of the femur, and on the head of the femoral stem, the forces of the abductor muscles were applied over the greater trochanter. Results are shown in terms of stress, strain, and deformation. The femur implanted with the porous stem showed a slight reduction of stress, strain and deformation in the femur, suggesting a better distribution and transport of the load along the femoral structure.