Stability of Contemporary Knee Arthroplasty

Total joint replacement is an efficacious treatment for osteoarthritis of hips and knees. Both total knee replacement (TKR) and total hip replacements (THR) have excellent implant survivorship. However, patient satisfaction is lower in TKR than THR. A possible cause of the discrepancy is the unnatural knee kinematics after TKR. Various implants designs have been developed to solve the problem. However, most of their designs are based on experimental data and little has been studied about their actual performance in vivo. In this study, the investigators will analyze the in vivo stability of the Global Medacta Knee Sphere (GMK Sphere) implant. Migration of the implants will be monitored with a high precision measuring method called Radiostereometric Analysis (RSA). The investigators assume the investigators study will contribute the development of more satisfying knee implants.