Contact mechanics analysis of natural hip joints and their artificial implants

Contact mechanics of natural hip joint and their artificial implants were investigated by using three dimensional anatomic and two and three dimensional axisymmetric finite element models in this study. Also two dimensional axisymmetric finite element models were created to investigate the effects of mesh size, loading, radial clearance, thickness of articular cartilage or cup etc. on contact mechanics of hip joint.It was concluded that loading has the most significant effect on contact mechanics of natural hip joint, loading and radial clearance have the most significant effect on contact mechanics of hemi-resurfacing arthroplasty of hip joint and radial clearance has the most significant effect on contact mechanics of metal-on-metal hip resurfacing arthroplasty.Stress analysis on bone were demonstrated that the stress shielding was occurred by implanting of femoral component and stress shielding has increased by using prosthesis in both sides of hip joint. However, stress shielding observed in both hemi-resurfacing and total resurfacing arthroplasty was lower than observed in total hip replacements.Clinical studies on hemi-resurfacing arthroplasty were indicated that a metal component on natural articular cartilage causes cartilage degeneration and thigh pain. Therefore, a compliant elastomeric material was applied to bearing surface of femoral component and a significant reduction in the predicted contact pressure on articular cartilage was observed by using this design.