Heelstrike and the pathomechanics of osteoarthrosis: a simulation study

A simulation model and trajectory matching method were developed to investigate the differences between two swing phase gait patterns; one giving rise to a large impulse at heelstrike, the other giving a small impulse. Subtle changes in the kinematics of the swing leg dramatically reduced the vertical contact velocity of the ankle at the moment of heelstrike. Phasing of the hip flexor muscles at the start of swing was responsible for the level of impulse observed at heelstrike.