Simulation of initial frontside and backside wear rates in a modular acetabular component with multiple screw holes

A sliding distance-based finite element formulation was implemented to pred ict initial wear rates at the front and back surfaces of a commercially ava ilable modular polyethylene component during in vitro loading conditions. W e found that contact area, contact stress, and wear at the back surface wer e more sensitive to the liner/shell conformity than the presence of multipl e screw holes. Furthermore, backside linear and volumetric wear rates were at least three orders of magnitude less than respective wear estimates at t he articulating surface. This discrepancy was primarily attributed to the d ifference in maximum sliding distances at the articulating surfaces (measur ed in mm) versus the back surface (measured in mu m). This is the first stu dy in which backside wear has been quantified and explicitly compared with frontside wear using clinically relevant metrics established for the articu lating surface. The results of this study suggest that with a polished meta l shell, the presence of screw holes does not substantially increase abrasi ve backside wear when compared with the effects of backside nonconformity. (C) 1999 Elsevier Science Ltd. All rights reserved.