The effect of vary varus malalignment on knee adduction moment during walking of human normal gait

This research aims to study the effect of varus malalignment to knee adduction moment (KAM) during walking using 3D gait simulation. KAM is the product of frontal ground reaction force and frontal lever arm; it is a major cause of pain at the lateral knee that is the general symptom of osteoarthritis (OA). For treatment, lateral fixed wedge insole and variable-stiffness shoes were used to treat OA patient for many years. The device helps reduce KAM while walking by shifting the center of pressure (CoP) from medial side to lateral side. Therefore, shifting CoP to lateral side for reducing frontal lever arm was incorporated into the design of the treatment devices for OA patient. In this paper, program simulation “Adams life module” was used to create 3D human model and simulate 3D gait to observe changes of KAM while vary the adduction angle between thigh and tibia. The simulation model was created based on normal gait profile data during the movement of the model. The result obtained from the simulation showed that the varus malalignment plays important roles on KAM. Increasing of the adduction angle leads to the higher value of peak KAM during walking.