Etiology-specific ankle dorsiflexion limitation reorganizes stance-phase biomechanics during barefoot gait: a time-resolved SPM1D and EMG study.

Purpose: This study aimed to comparatively analyze the lower-limb biomechanical differences between two populations with ankle dorsiflexion limitation during the stance phase of gait, thereby providing a scientific basis for clinical rehabilitation and athletic training.

Methods

12 males with congenital ankle dorsiflexion limitation and 12 males with acquired ankle dorsiflexion limitation, along with 12 healthy male controls were recruited into the study. Group differences in lower-limb kinematics, kinetics and surface electromyography (sEMG) during barefoot walking were subjected to statistical analysis using one-dimensional Statistical Parametric Mapping (SPM1D).

Results

The Congenital Ankle Dorsiflexion-Limited Cohort (CDFL) had greater ankle dorsiflexion during the support phase (22-42%) than the Acquired Ankle Dorsiflexion-Limited Cohort (ADFL) (p = 0.003), with increased terminal plantar flexion torque and positive power, and higher average activation intensity of the gastrocnemius medialis (GM), while the power trajectory was close to that of the control group. The ADFL had higher plantar flexion torque during 0-83% of the gait cycle ( p = 0.001), increased knee flexion throughout the gait cycle ( p = 0.014), and elevated negative knee power and positive hip power in the middle and late stages, with increased average activation intensity of the rectus femoris (RF) and decreased activation intensity of the GM and tibialis anterior (TA).

Conclusions

This study revealed phenotype-specific gait adaptations associated with different etiologies of ankle dorsiflexion limitation, ADFL predominantly exhibited a proximal-compensation pattern, whereas those with CDFL favored a distal strategy. These findings argue for etiology-tailored rehabilitation - strengthening ankle push-off and distal-proximal coordination in ADFL, and prioritizing terminal push-off and lateral stability in CDFL.