J Japanese Soc for Clin Biomech and Related Res, 23: 423-428, 2002

Fukuda Y, Tsuda E, Loh JC, Debski RE, Fu FH, Woo SL-Y


The purpose of this study was to show the center of axial tibial rotation at various different knee flexions during valgus torque thought to be the main load in pivot shift test.

Nine cadaveric knee specimens were tested using the robotic/universal force/moment sensor (UFS) testing system. Four pin markers were inserted into the proximal tibia. Their positions and a reference tibial point were determined by a mechanical digitizer (Microscibe, accurate to 0.1mm) and registered with respect to the UFS coordinate system. A valgus torque of 10 N-m was applied to the intact knee at full extension, 15°, 30°, 45°, 60°, and 90° of flexion and the remaining 5-DOF knee kinematics were recorded. The ACL was then transected. The same valgus torque was applied to the ACL-deficient knee and the change in knee kinematics was again recorded at each flexion angle. The center of axial tibial rotation was determined from a roentgenogram of the proximal tibial by calculating the knee kinematics from the 4 pin markers and the reference tibial point. The location of the centers at different knee flexion angles was normalized based on the tibial geometry.

With increasing knee flexion, the center of axial tibial rotation moved from the posterior intercondylar fossa towards the medical tibial spine in the intact ACL However, for the ACL-deficient knee, the center of rotation remained around the medial collateral ligament (MCL) insertion site at 15° and 30° of flexion. With further flexion, it moved towards the medial tibial spine, which was approximately the same location as for the intact knee.

We developed a new technique to show the center of axial tibial rotation in our research center. During valgus torque, the anterior tibial translation in the intact and ACL-deficient knee was restrained by the ACL and MCL, respectively. This method might be useful for evaluating the knee after ACL replacement.