Custom-Fit Total Knee Arthroplasty (OtisKnee) Results in Malalignment

We report on 4 patients who underwent total knee arthroplasty with OtisKnee system (OtisMed, Hayward, Calif). An image-free computer navigation system was used to evaluate the deformities and the recommended cuts. The recommended custom cuts were as follows: valgus/varus cuts on the femur (5.5° valgus to 0.5° varus) in reference to the mechanical axis, flexion cuts on the femur (4°-9° of flexion); femoral rotation was within 1° of the epicondylar axis; valgus/varus cut on the tibia (3° of valgus to 7.5° of varus); tibial slope (5.5° of anterior slope to 0.5° of posterior slope). The custom OtisKnee system guides recommended alignment of the components that was more than 3° off of mechanical axis. The potential for malalignment with this system places implants at high risk of early failure.