The original protocol intended to perform clinical assessment using the Nottingham Knee Score and the Knee Society Clinical rating system pre-and post-operatively, at six months, 1 year, and annually thereafter. Per Protocol Amendment 01 (effective June 18, 1999) clinical data would also be collected via the SF-12 questionnaire. Radiological evaluation would also use the Knee Society scoring system at the same time points. However, data collected included only the SF-12 and Oxford Knee Scores, comparing change from baseline at 6, 12, and 24 months after surgery.