Improvements of pedestrian leg protection should focus on knee ligaments damage and bone failure minimization. One method is to study injury mechanisms by focusing on the relationships between ultimate lateral bending and shearing at the knee level and potential ligament damage. A specific analysis of the LLMS model of the lower limb was used in pure lateral shearing and bending impact tests. The ultimate knee lateral bending and shearing for potential failure of ligaments (posterior cruciate, medial collateral, cruciates and tibial collateral) was evaluated to be close to 16° and 15 mm respectively.