Effects of Orthotic Insoles on Gait Kinematics and Low Back Pain in Subjects with Mild Leg Length Discrepancy.

BACKGROUND Mild leg length discrepancy (LLD) increases the biomechanical asymmetry during gait, which leads to low back pain (LBP). Orthotic insoles (OI) with a directly integrated heel lift were used to reduce this asymmetry and thus the associated LBP. The aim of this study was to analyze the biomechanical adaptations of the locomotor apparatus during gait and the subjective pain ratings before and after the establishment of OI use. METHODS Eight subjects with mild LLD ({less than or equal to} 2.0 cm) underwent 3-dimensional biomechanical analysis while walking, before and after 3 weeks of OI use. LBP was assessed separately before both measurement sessions using a visual analogue scale. RESULTS The analysis of the kinematic parameters highlighted individual adaptations. The symmetry index (SI) of Robinson indicated that OI had no significant effect on the kinematic gait parameters and an unpredictable effect across subjects. OI use significantly and systematically (in all subjects) reduced LBP (P < 0.05), which was correlated with changes in ankle kinematics (P = 0.02, r = 0.80). CONCLUSIONS The effects of OI on gait symmetry are unpredictable and specific to each subject's individual manner of biomechanical compensation. The reduction in LBP seems associated with the improved ankle kinematics during gait.