ADAPTIVE FINITE-ELEMENT MODELING OF LONG-TERM POLYETHYLENE WEAR IN TOTAL HIP-ARTHROPLASTY

Adaptive remeshing capability was added to an existing sliding-distanc e-coupled finite element model of polyethylene wear in total hip arthr oplasty. This augmentation allowed earlier postoperative wear simulati on to be extended to the clinically more significant long-term regimen (as long as 20 years). Loads and femoral head excursions were taken f rom a physically validated gait analysis model of a patient with an in strumented total hip replacement. For otherwise identical 22, 28, and 32 mm components, the least volumetric wear but the mast linear wear o ccurred for the 22 mm head. When the polyethylene thickness in a 22 mm component was reduced to the same as that in a 32 mm component, the v olumetric wear rate for the 22 mm component was still much less than t hat for the larger component, indicating that sliding distance (head s ize), rather than polyethylene liner thickness, was primarily responsi ble for the difference in rates. A ''28 mm'' series, for which head si zes were varied across the range of currently accepted industrial tole rances, showed that although initial wear rates were greatest for the least congruent articulations, the long-term volumetric wear was nearl y the same, regardless of initial clearance.