Application of Radiostereometric Analysis (RSA) to Triathlon Knee Components Inserted Using the OtisMed Custom-fit Total Knee Replacement System

The OtisMed Custom-fit system for total knee replacements replaces conventional surgical techniques for templating and intra-operative instrumentation with a preoperative virtual surgery process that utilizes 3D models of the affected knee from a pre-operative MRI or CT image. The 3D model of the affected knee is processed with a proprietary algorithm that virtually alters it to its pre-arthritic state by filling articular defects, removing osteophytes, and approximating the joint surface. The software then shape matches the knee replacement femoral and tibial components to the preathritic knee model and aligns the femoral component to the functional flexion-extension axis of the femur. The final preoperative step is the machining of custom biocompatible plastic cutting blocks that fit the arthritic knee. These cutting blocks are used during the knee replacement surgery to guide the bone cuts so that the replacement components are aligned for the individual patient.

In this study we propose to compare patients who have received total knee replacement components with the OtisMed Custom-fit procedure to those who have had the same components implanted in the conventional manner with Computer Assisted Surgery (CAS). The primary outcome will be micromotion of tibial and femoral implants at 1 and 2 years after surgery. Secondary outcomes will include subjective outcomes, accelerometric gait analysis, bone mineral density, full leg alignment, change in intra-operative frontal plane alignment, intra-operative deviations from the surgical plan, surgery duration, OR turnover time, number of instrument pans used, and length of hospital stay.