INTRAOPERATIVE ASSESSMENT OF KNEE KINEMATICS USING NAVIGATION

Abstract

Intraoperative assessment of knee kinematics should help surgeons optimizing total knee replacement. The purpose of this work was to validate information delivered by an adapted navigation system in 10 healthy cadaver knees and to investigate kinematics of 10 osteoarthritic (OA) knees in patients undergoing total knee replacement. The system displayed the magnitude of axial rotation, the position of the instantaneous centre of axial rotation and the displacements of the condyles. Successive cycles from full extension to 140° of fiexion in the same knee produced a mean external rotation of 19.7±10°, which was correlated to knee fiexion (r=0,60±0.2 in healthy knees, r=0.79±0.14 in OA knees). The center of axial rotation migrated posteriorly an average of 8.2 mm in both groups. The posterior displacements were 4.0 ±5.4 mm in healthy and 5±6.3 mm in OA knees for the medial condyle, and 20.9±9.1 mm in healthy and 20.3±10 mm in OA knees for the lateral condyle. The medial condyle lifted off beyond 110° of fiexion. Results in healthy knees were consistent with those obtained using fiuoroscopy and dynamic MRI. The kinematics of healthy and of OA knees with an intact anterior cruciate ligament did not differ significantly.