Cyclogram-Based Joint Symmetry Assessment After Utilization of a Foot Drop Stimulator During Post-stroke Hemiplegic Gait

: In the absence of standardized symmetry assessments, quantifying symmetry based on the kinematic evolution of lower extremity joints can elucidate gait irregularities. The objective was to develop a novel cyclogram based symmetry (CBS) method to quantify lower extremity joints' symmetry and assess the effect of 6-month utilization of foot drop stimulator (FDS) on CBS of the lower limbs during hemiplegic gait post stroke. Twenty-four participants (13 stroke and 11 healthy controls (HC)) performed 10 walking trials at a free cadence on level ground. Symmetry values were computed using geometric properties of bilateral cyclograms obtained from normalized sagittal ankle, knee and hip kinematics. CBS and traditional temporospatial symmetry values were compared between the two groups using independent sample t-test. Effect of FDS utilization on symmetry was assessed by paired sample t- test computed at baseline and 6-month follow up. The CBS method successfully showed that the HC group was significantly more symmetrical at the ankle (p=0.001), knee (p=0.001) and hip (p<0.005) compared with the stroke group. The stroke group showed significant increment in hip symmetry with FDS at baseline but did not show any significant CBS changes at follow up. Pearson correlations revealed that hip and knee CBS had a significant influence on overall walking speed. The CBS method presents a unique approach to calculate symmetry based on the kinematics of lower extremities during gait.