Acutely Normalizing Walking Speed Does Not Normalize Gait Biomechanics Post-Anterior Cruciate Ligament Reconstruction

Abstract

Aberrant gait biomechanics in individuals with anterior cruciate ligament reconstruction (ACLR) are linked to posttraumatic osteoarthritis (PTOA) development, indicating a need to normalize gait biomechanics to prevent PTOA. ACLR individuals walk slower than uninjured controls and slower speeds are associated with aberrant gait biomechanics. Yet, it is unclear if increasing walking speed normalizes gait biomechanics post-ACLR. Purpose To determine the effect of acutely increasing walking speed on gait biomechanics in ACLR individuals compared to their habitual speed and uninjured matched-controls. Methods Gait biomechanics were collected on 30 ACLR individuals (20 females, age: 22.0 ± 4.2 years, BMI: 24.0 ± 3.0 kg·m-2) at their habitual speed and at 1.3 m·s-1, a speed similar to controls, and 30 uninjured matched-controls (age: 21.9 ± 3.8, BMI: 23.6 ± 2.5) at their habitual speed. Functional waveform analyses compared biomechanics between: i) walking at habitual speed vs 1.3 m·s-1 in ACLR individuals; and ii) ACLR individuals at 1.3 m·s-1 vs controls. Results In the ACLR group, there were no statistically significant biomechanical differences between walking at habitual speed (1.18 ± 0.12 m·s-1) and 1.3 m·s-1 (1.29 ± 0.05 m·s-1). Compared with controls (habitual speed: 1.34 ± 0.12 m·s-1), the ACLR group while walking at 1.3 m·s-1 exhibited smaller vertical ground reaction force (vGRF) during early and late stance (13-28, 78-90% stance phase), greater midstance vGRF (47-61%), smaller early-to-midstance knee flexion angle (KFA; 1-44%), greater mid-to-late stance KFA (68-73, 96-101%), greater internal knee abduction moment (69-101%), and smaller internal knee extension moment (4-51, 88-96%). Conclusions Increasing walking speed to a speed similar to uninjured controls did not elicit significant changes to gait biomechanics, and ACLR individuals continued to demonstrate biomechanical profiles that are associated with PTOA development and differ from controls.