Effects of Sliding on the Stress State in UHMWPE Joint Replacement Components

Wear of ultra-high molecular weight polyethylene (UHMWPE) joint replacement components has become increasingly common as a long term problem in total joint arthroplasty. Retrieval studies have found pitting, delamination, and general wear as frequent modes of failure (Kilgus et al., 1991). Cyclic sliding is more likely to produce the fatigue damage observed than are normal and rolling contact loads (Blunn et al., 1991). It has also been suggested that the important parameter for propagation of surface cracks is the maximum principal stress, while the important value for subsurface crack propagation is the maximum shear (Tresca) stress (Bartel et al., 1986). A number of researchers have used experimental and finite element analyses to quantify the high stress state in UHMWPE components. The objective of this study was to investigate the effects of relative sliding motion between representative total knee components on the stress state in the polyethylene component using finite element analysis (FEA) and nonlinear material properties for UHMWPE.