Effect of Leg Length Discrepancy On Joint Contact Force During Gait Using Motion Tracking System: A Pilot Test

Abstract

Leg length discrepancy (LLD) often leads to a distraction of everyday routine, especially to a person with an active lifestyle. Normally, as there is a discrepancy between leg, the kinematic (i.e. gait pattern) as well as kinetic parameters (i.e. joint stresses) throughout the lower limb will be changed. This alteration will later develop more problems if it remains untreated. However, the way of treatments depending on the level of discrepancy. This pilot study aims to examine the effect of stress distribution on the LLD. There are two subjects participate; the true LLD, and simulated LLD. The true LLD comes from the patient with a history of Total Hip Replacements acts as a control subject to verify the simulated subject (healthy subject with no history of orthopaedic surgery), meets the exacts behaviour of real LLD. Nine levels of LLD are implemented, starting from 0cm up to 4cm with 0.5cm interval each. To analyse the joint reaction force, inverse dynamic modelling software was used, Freebody v2.1. As the results obtained, it is shown that ankle gives greater peak value, following by hip, tibiofemoral, and patellofemoral joint. An implication of this study is the possibility that the subject tries to compensate the LLD posture during gait. Hence, reduce the contact within the joint, so the contact area of the ankle become smaller resulting greater stress.