The Triathlon® Cruciate Retaining (CR) Total Knee System components are for use in cemented total knee arthroplasty for painful, disabling joint disease of the knee resulting from non-inflammatory degenerative joint disease (including osteoarthritis, traumatic arthritis or avascular necrosis) or rheumatoid arthritis (excluded from this study according to protocol). The components are designed to improve range of motion (ROM) and stability. This study serves to demonstrate that subjects have reduced pain, increased ROM and improved stability following implantation with the Triathlon Cruciate Retaining (CR) Total Knee System as compared to the historical control.