Simple Gait Symmetry Measures Based on Foot Angular Velocity: Analysis in Post Stroke Patients.

In this paper, we propose symmetry measures for post stroke assessment based on gait signal profiles from inertial sensors. Ten healthy controls and eight post stroke patients performed 6-Minute Walk Tests while wearing an inertial sensor on top of each shoe. Symmetry measures based on the linear correlation and the normalized sample distance between left and right foot pitch angular velocity showed high discriminating power to differentiate post stroke gait from healthy controls (Cliff's D = 0.95, Wilcoxon test p<0.001). The proposed symmetry measures are simple to estimate and do not require spatiotemporal gait parameters while they provide comparable discriminating power than symmetry measures based on spatiotemporal gait characteristics such as maximum angular velocity and stance ratio of each cycle. The proposed symmetry measures have the potential for generalization in wearable sensor based gait symmetry assessment.

Gait Symmetry Assessment with a Low Back 3D Accelerometer in Post-Stroke Patients.

Gait asymmetry is an important marker of mobility impairment post stroke. This study proposes a new gait symmetry index (GSI) to quantify gait symmetry with one 3D accelerometer at L3 (GSIL3). GSIL3 was evaluated with 16 post stroke patients and nine healthy controls in the Six-Minute-Walk-Test (6-MWT). Discriminative power was evaluated with Wilcoxon test and the effect size (ES) was computed with Cliff's Delta. GSIL3 estimated during the entire 6-MWT and during a short segment straight walk (GSIL3straight) have comparable effect size to one another (ES = 0.89, p < 0.001) and to the symmetry indices derived from feet sensors (|ES| = [0.22, 0.89]). Furthermore, while none of the indices derived from feet sensors showed significant differences between post stroke patients walking with a cane compared to those able to walk without, GSIL3 was able to discriminate between these two groups with a significantly lower value in the group using a cane (ES = 0.70, p = 0.02). In addition, GSIL3 was strongly associated with several symmetry indices measured by feet sensors during the straight walking cycles (Spearman correlation: |ρ| = [0.82, 0.88], p < 0.05). The proposed index can be a reliable and cost-efficient post stroke gait symmetry assessment with implications for research and clinical practice.