| Total knee arthroplasty is performed to relieve pain and improve function in individuals with degenerative joint disease. Surgical technique affects the long term success of this procedure; improper alignment can lead to loss of motion, accelerated wear, and even dislocation of the implants. Surgical navigation systems have been developed to help orthopaedic surgeons achieve accurate implant alignment, and the use of these systems has expanded in recent years. However, the performance of the algorithms used to determine implant alignment in navigation systems has not been rigorously evaluated.; To address this challenge, we created a surgical navigation system for total knee arthroplasty. We used the system to assess the accuracy of algorithms that locate the center of the hip and ankle joints, key landmarks used in implant alignment. We developed and evaluated the performance of a "pivoting" algorithm that estimates the location of the hip joint center from motion data with greater accuracy and less sensitivity to noise than previous algorithms. We also tested and refined methods that locate the center of the ankle. These studies improved the accuracy of core algorithms for navigation systems.; We used our navigation system as a measurement tool to study surgical technique and knee kinematics. We discovered that a common method employed by navigation systems to establish femoral rotational alignment, identifying the location of the epicondyles with a digitizing probe, was no more reliable than traditional methods and that all techniques were highly variable. These findings emphasized the need for future refinements in navigation technology to improve implant rotational alignment.; We performed the first intra-operative characterizations of the kinematics of advanced osteoarthritic knees before and after total knee arthroplasty. Advanced osteoarthritic knees displayed abnormal varus/valgus rotations, a reduced "screw-home" motion, and a normal anterior-posterior motion of the femur on the tibia. Following total knee arthroplasty, normal varus/valgus rotations were not restored, the "screw-home" motion was not changed, but an abnormal anterior translation of the femur in early flexion was introduced.; This dissertation advances the scientific development and clinical applications of orthopaedic surgical navigation. |
