A novel registration method for computer-assisted total knee arthroplasty using a patient-specific registration guide.

Total knee arthroplasty (TKA) is a surgical method for replacing a degenerated or diseased knee joint that can no longer perform daily functions with an artificial knee implant. In TKA, the artificial knee implant should be inserted such that it aligns well with the mechanical axis of the leg. Thus, precise bone cutting is essential. To improve TKA outcomes, a registration process is performed to locate the predetermined bone cutting area by calculating the position and posture of the femur and tibia. In this article, we propose a patient-specific registration guide that is able to significantly reduce registration time and effort without loss of accuracy. Furthermore, the patient-specific registration guide can be implemented with real-time registration, allowing continuous surgical information to be provided without the insertion of any tracking devices. The precision and accuracy of the proposed registration guide were confirmed through animal tests with a digitizer, stereo camera, and linear motion generator. The error of our registration method, including measurement and guide attachment errors, reached a maximum of 0.321 mm for one pair of cow legs.