Wear performance of all-polymer PEEK articulations for a cervical total level arthroplasty system

Pin-on-plate wear testing of polyetheretherketone (PEEK) was performed in a PEEK-on-PEEK configuration to explore the tribology of this rather uncommon contact configuration. To illustrate its possible application, a total level cervical arthroplasty system was described. Also, it was noted that previous pin-on-plate and simulator studies of this type of material pairing had been conducted. The present study continued the protocol of testing under an adverse loading regime that was originally introduced by Austin et al. to investigate the sensitivity of all-polymer PEEK articulations to previous wear damage. A gravimetric wear assessment protocol was used that avoided vacuum drying. The lower wear of polyacrylonitrile carbon fibre-reinforced PEEK compared with unfilled PEEK, as found by many other studies, was confirmed. PEEK was shown to have remarkably low wear despite previous adverse load testing. The coefficient of friction was found to be quite high (up to 0.5) and this might have clinical implications. Finally, it was noted that the comparison of wear factors and wear amounts from the present study (and other previous studies) with those of the very similar study by Scholes and Unsworth suggested that their laboratory model might be overstating the wear of all-polymer PEEK articulations for potential applications in orthopaedic tribology.