In pedestrian injury biomechanics, knees and lower legs are highly recruited, leading to joint damage and bones failures. Safety improvements should mainly focus on knee ligaments injury minimization. To investigate the corresponding injury mechanisms and postulate on injury criteria risk, both experimental and finite element simulation approaches were performed. The lower limb behavior was first studied in lateral bending and then in lateral shearing impact tests in order to isolate injury mechanisms effects. The tests consisted in evaluating lower limb forces and kinematic through a 37kg guided impact with velocities ranged between 15 & 20kph. 35 tests were performed on isolated PMHS lower limbs. Response corridors for the time history about the mean response curve ± one standard deviation with the Maltese procedure were established. The observed damages were contact injuries (head of fibula and lateral tibial condyle fractures), ligament injuries (cruciates and collaterals ligaments according to the tests) and bone fractures (extra and diaphysis). These experimental tests were simulated using a finite element model of the lower limb (with extended impact velocities). The model response analysis (bone Von Mises stress levels, Ligaments global and local strain levels, knee rotation and shearing measurements) was performed during each step of the impact chronology. It leads to postulate on injury criteria for knee soft tissues based on the knee ultimate lateral bending (~16°) and shearing levels (~15mm). These approaches by coupling PMHS experimentation and numerical simulation ensure an accurate description of pedestrian lower limb trauma in terms of injury chronology and threshold. These results were also relevant with accidentology and clinical knowledge, especially with the evaluated potential injuries.