Patellar crepitus and clunk following posterior cruciate substituting total knee arthroplasty is a persistent problem with a reported incidence as high as 14%. The development of this complication necessitates additional surgery in some patients. Numerous etiologies have been reported including design of the femoral component. Due to a higher than desired incidence of patellar crepitus with the PFC Sigma PS TKA, design modifications of the trochlear groove of the femoral component were introduced with the release of the PFC Sigma HP PS femoral component. The purpose of the proposed study is to evaluate the incidence of patellar crepitus after posterior cruciate substituting TKA utilizing the PFC Sigma vs. the PFC Sigma HP PS femoral components.