Intraoperative passive flexion kinematics of osteoarthritic knees before and after mobile bearing PCR-TKA

Ⓡsystem used in this study is an image-free navigation system. Two trackers equipped with reference arrays was implanted in the distal femur and in the proximal tibia. Based on the kinematic and anatomical registration data, three-dimensional relationship between the tracker and each of the femur and the tibia was computed. TKA procedure was carried out using the resection block attached to this navigation system. Kinematic analysis using the navigation system Intra-operative passive flexion kinematics were measured by the Orthopilot Ⓡ system and analyzed by dedicated software (OrthoPilot TKA Version4.2 Kobe version). The software allows anatomical and kinematic acquisitions and provides real-time display of knee alignment during surgery and standard kinematic evaluations. With the help of this system, three dimensional tibio-femoral kinematics could be continuously monitored though range of motion with a sampling rate of 5/sec or at each of 10-degrees increments during flexion. Kinematic recording was preformed both before and after TKA implantation. During the kinematic measurement, an assistant surgeon held the thigh to align it perpendicularly while the operating surgeon gently held the heel and passively moved the knee from full extension to full flexion inducing unconstrained motion. The kinematic measurement for the TKA implanted knee was performed after repair of the parapatellar arthrotomy and skin closure.