The Danger of Walking with Socks: Evidence from Kinematic Analysis in People with Progressive Multiple Sclerosis

Abstract

Multiple sclerosis (MS) is characterized by gait impairments and severely impacts the quality of life. Technological advances in biomechanics offer objective assessments of gait disabilities in clinical settings. Here we employed wearable sensors to measure electromyography (EMG) and body acceleration during walking and to quantify the altered gait pattern between people with progressive MS (PwPMS) and healthy controls (HCs). Forty consecutive patients attending our department as in-patients were examined together with fifteen healthy controls. All subjects performed the timed 10 min walking test (T10MW) using a wearable accelerator and 8 electrodes attached to bilateral thighs and legs so that body acceleration and EMG activity were recorded. The T10MWs were recorded under three conditions: standard (wearing shoes), reduced grip (wearing socks) and increased cognitive load (backward-counting dual-task). PwPMS showed worse kinematics of gait and increased muscle coactivation than controls at both the thigh and leg levels. Both reduced grip and increased cognitive load caused a reduction in the cadence and velocity of the T10MW, which were correlated with one another. A higher coactivation index at the thigh level of the more affected side was positively correlated with the time of the T10MW (r = 0.5, p < 0.01), Expanded Disability Status Scale (EDSS) (r = 0.4, p < 0.05), and negatively correlated with the cadence (r = -0.6, p < 0.001). Our results suggest that excessive coactivation at the thigh level is the major determinant of the gait performance as the disease progresses. Moreover, demanding walking conditions do not influence gait in controls but deteriorate walking performances in PwPMS, thus those conditions should be prevented during hospital examinations as well as in homecare environments.

Keywords: T10MW; accelerator; gait analysis; inertial sensor; kinematics; multiple sclerosis; surface EMG.

Figure 1

Inter- and intra group comparisons of spatiotemporal parameters. Significant group differences in time (a), cadence (b), velocity (c) and step size (d) were found in all three conditions. Intra-group comparison between shoes and socks conditions also showed significant differences in time (e), cadence (f), velocity (g), and step length (h) in PwPMS, while only step length in the HCs. For the comparison of single and dual tasks, longer time (i), lower velocity (k), and shorter step length (l) was found when PwPMS were performing a DT compared to performing a single task, while in the HCs only significantly reduced cadence (j) was found. *: p < 0.01 in post hoc analysis ((a–d): between-group comparison; (j–l): within-group comparisons).

Figure 2

The inter-group difference of the coactivation index. Two-way ANOVA showed significant group difference of coactivation in both the MA and LA side in RF-BF (a,b) and GM-TA (c,d), while no significant difference was found among conditions. *: p < 0.01 in posthoc analyses.

Figure 3

The correlations among kinematics and clinical assessments when the walking conditions changed for PwPMS. (a,b): x-axis: the difference between the shoes and the socks conditions (socks minus shoes); y-axis: the difference between the single task and DT conditions (single minus DT, both performed with shoes). Positive correlations were found in velocity (r = 0.3662, p = 0.0141) and cadence (r = 0.4158, p = 0.0076) between the differences of the shoes vs. socks condition and the single vs. DT conditions. (c,d): A significant negative correlation was found between the BBS scores and the time increases from shoe to sock conditions (r = −0.3901, p = 0.0141), and a trend correlation was found with time increases of single versus dual tasks (r = −0.3247, p = 0.0437).