Over 80,000 knee replacement procedures were performed in 2013 in the UK alone and a total knee replacement (TKR) remains the “gold standard”, incorporating a metal femoral component, rounded at the end to mimic the natural anatomy of the joint, and a flatter polyethylene tibial insert placed within a metal tibial tray. Partial, or unicompartmental, knee replacements are also performed with the medial, lateral of patello-femoral parts of the knee replaced.
There is a need for understanding the failure modes and mechanisms that occur in knee replacements in order to improve the success of knee replacements. Identifying the surgical, implant and patient (SIP) factors that lead to failure will help in management of current patients and improve outcome for future patients.
UHMWPE is the original gold standard polyethylene material in both knees and hips however in order to enhance wear resistance and resistance to oxidation, a number of different types of polyethylene have been introduced, including crosslinked and those with antioxidants such as vitamin E. Whilst the modification of polyethylene components in hip and knee implants has generally presented with encouraging clinical results, the long-term behaviour of these is unclear and the variables influencing polyethylene damage are unknown.
Charitable funding from the Helios ENDO-Klinik Orthopaedic Hospital in Hamburg, Germany has enabled us to purchase a Fourier Transform Infrared Spectroscopy (FTIR) machine to investigated the oxidation of new and retrieved polyethylene samples.