Abstract
BACKGROUND: Ankle sprains, the most common sports injury, often progress to functional ankle instability (FAI), characterized by recurrent instability and neuromuscular deficits. This study utilizes three-dimensional (3D) gait analysis system to quantify lower limb biomechanical alterations in FAI during gait, aiming to identify objective markers for guiding targeted rehabilitation strategies. STUDY DESIGN: This case-control study enrolled 31 matched subject pairs (FAI subjects vs. healthy controls) through propensity score matching based on stringent inclusion/exclusion criteria. Demographic data were collected, and functional assessments including the Cumberland Ankle Instability Tool (CAIT), American Orthopedic Foot and Ankle Society (AOFAS) scale, and Visual Analog Scale (VAS) for pain were administered. 3D gait analysis was performed using an infrared motion capture system (BTS SMART-D 400) to quantify biomechanical parameters characterizing FAI-related gait abnormalities. RESULTS: In individuals with FAI gait quality is significantly compromised, predominantly evidenced by alterations in pelvic tilt (P < 0.05, r = - 0.67, 95% CI [- 4.75, - 1.95]), as well as deviations in hip ad-abduction (P < 0.05, r = 0.44, 95% CI [- 3.80, - 0.20]). This condition is further characterized by a marked reduction in sagittal plane flexion of the hip joint (P < 0.05, r = - 0.44, 95% CI [0.60, 8.25]) and a decrease in the maximum dorsiflexion of the ankle joint (P < 0.05, r = - 2.56, 95% CI [- 3.76, 0.50]). Additionally, there is an observed increase in the dorsiflexion angle at the forefoot (P < 0.05, r = - 11.04, 95% CI [1.36,4.94]), coupled with a decrease in the dorsiflexion angle at the hindfoot (P < 0.05, r = - 13.16, 95% CI [0.25,4.10]). CONCLUSIONS: Post-traumatic degradation of peripheral sensorimotor feedback following ankle injury induces central nervous system-mediated motor control reorganization, resulting in altered movement strategies that manifest through modified kinematic coordination patterns across the hip, knee, and ankle joints.