Inter-segmental coordination amplitude and variability differences during gait in patients with Ehlers-Danlos syndrome and healthy adults

Background: There is limited research examining gait and inter-segmental coordination in patients with EhlersDanlos syndrome. The objective was to compare lower extremity inter-segmental coordination amplitude and variability during gait between patients with Ehlers-Danlos syndrome and healthy adults. Methods: This cross-sectional study included participants with Ehlers-Danlos syndrome (n = 13) and healthy adults (n = 14). Gait data were acquired using a motion capture system and force plates. Participants ambulated at self-selected speeds for five trials. Inter-segmental coordination was quantified using continuous relative phase, which examined the dynamic interaction between the thigh-shank and shank-foot paired segments (i.e. phase space relation). A 2-way mixed analysis of variance examined the effects of groups (Ehlers-Danlos and healthy) and gait phases (stance and swing phase) on inter-segmental coordination amplitude and between-trial variability. Effect sizes were calculated using Cohen's d. Findings: The Ehlers-Danlos group had greater inter-segmental coordination variability compared to the healthy group for foot-shank and shank-thigh segment pairs in the sagittal plane over stance and swing phases (P = 0.04; small to large effect sizes). The Ehlers-Danlos group also had greater variability in the frontal plane at the foot shank segment pair during stance phase (P = 0.03; large effect). There were no differences in inter-segmental coordination amplitude between groups (P = 0.06 to 0.85). Interpretation: Patients with Ehlers-Danlos syndrome have more variability between gait trials in lower limb motor coordination than healthy adults. This may be related to the impaired proprioception, reduced strength, pain, or slower gait speed seen in this population.