Background
Oxidized zirconium (OxZr) has demonstrated excellent mechanical properties in vitro when used against articular cartilage; less coefficient of friction and less chondral damage have been found when compared with cobalt–chromium (CoCr) implants. However, controversy exists as to whether implants with a zirconium femoral component articulate safely with a native patella in total knee arthroplasty (TKA). To answer this question, the clinical and radiographic results were analysed from a group of patients who underwent a TKA with patella retention; the OxZr versus CoCr femoral components were compared.