Investigation of Wear Behavior of Biopolymers for Total Knee Replacements Through Invitro Experimentation

The average life span of knee prosthesis used in Total Knee Replacement (TKR) is approximately 10 to 15 years. Literature indicates that the reasons for implant failures include wear, infection, instability, and stiffness. However, the majority of failures are due to wear and tear of the prosthesis. The most common biopolymer used in TKR  is Ultra High Molecular Weight Polyethylene (UHMWPE). Prevailing research reports that implants are restrained by tiny UHMWPE debris generated by long term friction between the femoral component and polyethylene articulating surface. This necessitates an alternative material with high wear-resistance to reduce the wear rate. Polyether ether ketone (PEEK) is one of the biopolymers expected to possess better mechanical properties and biocompatibility with surrounding tissue and hence can be suitable for orthopedic applications. In this regard, a study on UHMWPE and PEEK biopolymers was carried out and tribological behavior was examined. The effect of process parameters such as normal load and speed on the tribological performance of biopolymers were evaluated. The experiment plan was designed as per Taguchi’s Design of Experiments methodology. An empirical relation between wear and process parameters was established using linear regression analysis. Microanalysis and failure analysis of worn-out surfaces of both the biopolymers was carried out using  Scanning Electron Microscopy(SEM). Results exhibit that UHMWPE had deep grooves as compared to finer grooves on PEEK indicating a low wear rate in the latter. This was also supported by the experimental results suggesting PEEK as a suitable alternative biopolymer for TKR.