Individuals with Unilateral Transfemoral Amputation Rely More on Hip Compensation When Walking in Low Ambient Light Environment

Background and/or Objectives: To examine the effects of ambient lighting on hip joint kinetics and kinematics in individuals with unilateral transfemoral amputation (TFA) during walking.

Design: cross-sectional study.

Setting : Controlled laboratory environment.

Participants : We recruited 10 individuals with unilateral TFA (6 male, age= 36.9 ± 10.4). Participants walked at a self-selected speed (0.73± 0.1 m/s) under light-on and light-off conditions on an instrumented split-belt treadmill.

Interventions: not applicable

Main Outcome Measures: Peak sagittal and frontal plane hip biomechanics during the stance phase, as well as hip angles at peak internal joint moments. Internal joint moments were normalized to body weight and height (%BW*HT). A two-way repeated measure multivariate analysis of variance was performed to compare outcome measures between limbs, lighting conditions, and their interaction. The α level was set at 0.05.

Results: Across both lighting conditions, the TFA limbs displayed lower peak hip flexion (HF) (p= 0.003, η2= 0.637, limb difference= 8.8°) and lower HF at peak hip extension moment (HEM) (p < 0.001, η2= 0.823, limb difference= 19.8°) compared to their intact limbs. A significant interaction effect was observed for peak HEM (p= 0.003, η2= 0.645), with post-hoc analyses indicating greater intact limb peak HEM in the light-off condition (p= 0.014, light condition difference= 0.32 %BW*HT). No other significant result was observed.

Conclusions: Current findings provide initial insights into the effect of ambient light on joint biomechanics in individuals with unilateral TFA. Consist with prior evidence, the intact limbs not only compensated for the TFA limbs but demonstrated even greater joint loading under low-light conditions. These findings highlighted the need for developing targeted interventions that address environmental lighting challenges to improve walking strategies in individuals with TFA.