Wear properties of poly-ether-ether-ketone bearing combinations under zero and cross shear kinematics in total knee arthroplasty.

Poly-ether-ether-ketone (PEEK), having shown favorable biocompatibility in spinal applications is being considered as an alternative biomaterial in orthopaedics, either as part of an all-polymer bearing couple, or a replacement for the metallic component in hard-on-soft bearings. Throughout the literature ultra-high molecular weight polyethylene exhibits a range of wear behavior dependent upon the amount of cross shear (CS) present in the bearing motion; in comparison, the behavior of PEEK bearing combinations subject to cross shear conditions is less understood. The aim of this study was to investigate the effect of cross shear on PEEK-on-PEEK and PEEK-on-Metal bearing couples. Wear tests were conducted using a four station pin-on-plate rig capable of uni-directional motion (zero cross shear) and multidirectional motion (cross shear); reciprocation (1 Hz), rotation (0 or 1 Hz), with gravimetric wear analysis used to determine the wear factors. The combined wear factors from the PEEK pins articulating on either PEEK or metal plates in this study suggest that it is preferable to use PEEK-on-Metal bearing couples under zero cross shear kinematic conditions and PEEK-on-PEEK for high cross shear applications. PEEK appears to demonstrate a CS dependency when articulating on hard surfaces. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 445-453, 2019.