Lower- and Upper-Body Control during standing for Individuals with SCI

Lee, Jae 1; Yoo, Jaeeun 1; Chan, Katherine 2; Unger, Janelle 3; Musselman, Kristin 2; Masani, Kei 1

1. The Institute of Biomaterials & Biomedical Engineering, University of Toronto; 2. Department of Physical Therapy, University of Toronto; 3. Rehabilitation Science, University of Toronto

Introduction

Individuals with incomplete spinal cord injury (iSCI) often suffer from impaired ability to maintain balance during standing. Since it is known that the coordination between the upper and the lower body plays an important role in stabilizing the body for able-bodied (AB) individuals, we hypothesize that individuals with iSCI do not sustain upper- and lower- body coordination, causing difficulties in maintaining their balance. Here in this study, we tested the coordination of the body using kinematic and kinetic analyses during standing for individuals with iSCI.

Method

Twelve young AB individuals (6 female and 6 male; 25.6±5.3 years old), eleven individuals with SCI (6 female and 5 male; 59.5±11.6 years old), and eleven age- and gender- matched AB individuals participated. The participants were instructed to perform quiet standing for 150 seconds with their eyes open and closed. We only present the eyes open condition here due to the limited space. Using motion capture and force platform systems, we measured the kinematics and kinetics data. Out of the eleven individuals with SCI, only data from eight participants were analyzed due to technical difficulties. We calculated the center-of-mass (COM) of the lower body (hip-knee-feet), upper body (head-hip) and the whole-body, as well as the upper and the lower body segment angles. The root-mean square of the acceleration data were used to quantify the fluctuation. We also evaluated the coordination between the two segments using the coordination index, based on our previous study. The analysis of variance (ANOVA) with Tukey HSD as the post-hoc analysis was used to compare the measures among the three groups.

Result

We found that the whole-body COM linear accelerations were significantly different among the three groups (ANOVA: p = 0.020). The post-hoc analysis revealed that the COM acceleration in iSCI was significantly larger than the other two groups  (AB-young vs iSCI: p=0.032 and AB-matched vs iSCI: p = 0.035), indicating that iSCI participants have compromised balancing abilities. We also found that the lower body angular acceleration was larger for iSCI participants than for AB participants (ANOVA: p=0.014; AB-young vs iSCI: p=0.036 and AB-matched vs iSCI: p = 0.017). On the contrary, the upper body fluctuations was not different between individuals with SCI and AB participants (ANOVA: p=0.100; AB-young vs iSCI: p=0.136 and AB-matched vs iSCI: p = 0.138). The coordination index was not different among the three groups (ANOVA: p=0.783).

Conclusion

We demonstrated that individuals with iSCI sway more during standing, indicating that they have compromised ability to maintain balance. Despite this instability, the lower- and upper- body  coordination was equivalent to AB participants. This instability is caused by the reduced control in their ankle joints. Therefore, improving ankle control would be critical in improving their overall standing balance.