Leg Length Discrepancy: Dynamic Balance Response during Gait

Area of Science:

• Biomechanics
• Human Movement Analysis
• Orthopedics

Background:

• Dynamic balance is crucial for daily activities and fall prevention.
• Leg length discrepancy (LLD) is a common condition affecting posture and gait.
• Existing research lacks experimental data on LLD's impact on dynamic stability during walking.

Purpose of the Study:

• To investigate the effects of simulated leg length discrepancy (LLD) on dynamic stability during walking.
• To analyze changes in ground reaction forces (GRF), center of pressure (COP), and center of mass (COM) with varying LLD.
• To establish a quantifiable relationship between LLD magnitude and stability parameters.

Main Methods:

• Eighteen healthy subjects walked at controlled speeds (1.0-2.0 m/s).
• Simulated LLD was introduced using insoles ranging from 0.5 cm to 4.0 cm under one foot.
• Data collected using force plates and motion analysis, focusing on VGRF, COP, and COM trajectories.

Main Results:

• Greater forces were exerted on the shorter leg during single-leg stance.
• LLD significantly altered the displacement of COM trajectories in medial-lateral (ML) and vertical directions.
• COP distribution shifted towards the shorter leg, and significant changes in COP-COM distance were observed in the ML direction.

Conclusions:

• Leg length discrepancy demonstrably affects dynamic stability during walking.
• The study provides evidence for significant changes in gait parameters with LLD, particularly from 2.5 cm upwards.
• Findings contribute to understanding LLD's role in balance control and fall risk assessment.