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Corrective Insoles Enhance Center of Mass Stability During Stair Descent in Individuals with Leg Length Discrepancy

Authors :

Kasra Alborzi¹ Alireza Hashemi Oskouei² Pouya Mansouri³ Seyed Mehran Ayati Najafabadi⁴

1- دانشکده مهندسی پزشکی، دانشگاه صنعتی سهند، تبریز، ایران 2- دانشکده مهندسی پزشکی، دانشگاه صنعتی سهند، تبریز، ایران 3- دانشکده مهندسی پزشکی، دانشگاه صنعتی سهند، تبریز، ایران 4- دانشکده مهندسی پزشکی، دانشگاه صنعتی سهند، تبریز، ایران

Keywords :

Dynamic Balance،Leg Length Discrepancy،Stair Descent

Abstract :

Leg length discrepancy (LLD) is linked to reduced dynamic stability and significant changes in gait biomechanics. This study quantified center of mass (COM) trajectory and sway measures in individuals with leg length discrepancy during stair descent, with and without corrective insoles, to determine whether such orthotic intervention can mitigate postural control deficits and improve stability. Ten male participants with structural leg length discrepancy (30 ± 10 mm) completed stair descent trials with and without custom corrective insoles. Three-dimensional kinematics were recorded at 100 Hz using a seven-camera motion capture system, with COM trajectories computed for sagittal, frontal, and transverse planes. The insole height matched the measured discrepancy plus 10%, and trials were repeated three times per condition. Independent t‑tests compared sway-related COM parameters between conditions, with significance set at p < 0.05. In the frontal plane, corrective insole usage during stair descent in individuals with leg length discrepancy yielded significant improvements in balance control, with range of motion and maximum deviation of the center of mass reduced by 37.7% and 37.9%, respectively (p < 0.04, p < 0.03). In the transverse plane, decreases of 44.6% in range of motion and 58.1% in maximum deviation (p < 0.030, p < 0.030) indicated enhanced rotational stability. Sagittal plane measures demonstrated small, non‑significant reductions (p > 0.05). Corrective insoles substantially minimized frontal and transverse plane sway, supporting their application as a non‑invasive, cost‑efficient strategy to enhance dynamic stability in individuals with leg length discrepancy during stair descent.