An experimental method for assessing the tolerance to bending moment in the lateral direction of the extended knee joint has been developed. The load response of the lower extremity was measured by means of force transducers. The bending moment transferred through the entire knee joint was calculated, and the motion of the specimen registered by high speed photography. The bending moment in the lateral direction at the first sign of damage of the entire extended knee joint was determined. Damages were assessed by both measuring the knee joint condition, and dissecting the knee region. Seventeen tests were carried out under dynamic conditions. The first and most common damage type to the entire knee joint in this loading configuration was stretching and rupture or avulsion of the medial collateral ligament (MCL). These damages are generated by identical mechanisms, that is to say tensional forces acting on the medial knee structures. The mean peak moment correlated with this damage mechanism was 101 (about 21) Nm for an impact velocity of 16 km/h, and 123 (about 35) Nm for an impact velocity of 20 km/h. The mechanisms caused damage of the knee joint, when the lower extremity was bent approximately 10 degrees in the lateral direction at the knee joint.
Abstract