Biphasic finite element modelling of contract mechanics of hemi-of human hip joint. Part II: Polycarbonate urethane on cartilage contact

Poroelastic finite element study was performed to compare the contact mechanics of employing different biomaterials such as metal and polycarbonate urethane for hemiarthroplasty hip resurfacing. The effects of loading, radial clearance and cartilage thickness on the predicted maximum contact pressure and pore pressure were investigated in this study. The femoral component, considered in part 1, was modified on the bearing surface by using a polycarbonate urethane layer with thickness of 2 mm to investigate the effect of soft bearing material against the articular cartilage. The stress distributions within the components of hemiarthroplasty of hip joint were also studied. The most significant effect on the predicted maximum contact pressure and pore pressure for metal on cartilage and polycarbonate urethane on cartilage models was found to be cartilage thickness in this study. Therefore it was concluded that because of cartilage degeneration by time, using soft femoral component decreased the predicted maximum contact pressure and pore pressure on cartilage in this study. Varying the radial clearance between femoral component and articular cartilage and applied load did not show a significant effect on the contact mechanics between metal on cartilage and polycarbonate urethane on cartilage models. Also a comparison of the predicted maximum von Mises stresses within the components of metal on cartilage and polycarbonate urethane on cartilage models had only small differences, ranged from 0 to 10%.