Center-of-pressure total trajectory length is a complementary measure to maximum excursion to better differentiate multidirectional standing limits of stability between individuals with incomplete spinal cord injury and able-bodied individuals

Abstract

BackgroundSensorimotor impairments secondary to a spinal cord injury affect standing postural balance. While quasi-static postural balance impairments have been documented, little information is known about dynamic postural balance in this population. The aim of this study was to quantify and characterize dynamic postural balance while standing among individuals with a spinal cord injury using the comfortable multidirectional limits of stability test and to explore its association with the quasi-static standing postural balance test.MethodsSixteen individuals with an incomplete spinal cord injury and sixteen able-bodied individuals participated in this study. For the comfortable multidirectional limits of stability test, participants were instructed to lean as far as possible in 8 directions, separated by 45° while standing with each foot on a forceplate and real-time COP visual feedback provided. Measures computed using the center of pressure (COP), such as the absolute maximal distance reached (COPmax) and the total length travelled by the COP to reach the maximal distance (COPlength), were used to characterize performance in each direction. Quasi-static standing postural balance with eyes open was evaluated using time-domain measures of the COP. The difference between the groups and the association between the dynamic and quasi-static test were analyzed.ResultsThe COPlength of individuals with SCI was significantly greater (p ≤ 0.001) than that of able-bodied individuals in all tested directions except in the anterior and posterior directions (p ≤ 0.039), indicating an increased COP trajectory while progressing towards their maximal distance. The COPmax in the anterior direction was significantly smaller for individuals with SCI. Little association was found between the comfortable multidirectional limits of stability test and the quasi-static postural balance test (r ≥ −0.658).ConclusionStanding dynamic postural balance performance in individuals with an incomplete spinal cord injury can be differentiated from that of able-bodied individuals with the comfortable limits of stability test. Performance among individuals with an incomplete spinal cord injury is characterized by lack of precision when reaching. The comfortable limits of stability test provides supplementary information and could serve as an adjunct to the quasi-static test when evaluating postural balance in an incomplete spinal cord injury population.

Balance Confidence Is Related to Features of Balance and Gait in Individuals with Chronic Stroke

“…Changes in the position of the COP contribute to the control of the position of the body's centre of mass [26]. Balance confidence has been found to be associated with impaired control of quiet standing in individuals with sub-acute stroke, with a negative relationship between balance confidence and antero-posterior COP excursion during quiet standing [11].…”

Postural Control Strategy After Incomplete Spinal Cord Injury: Effect of Sensory Inputs on Trunk-leg Movement Coordination

“…A significant challenge for individuals with iSCI is to maintain postural stability while recovering walking function [7]. iSCI affects the ability to safely stand and perform functional activities in this position [8]. The literature has reported a high occurrence of falling among the SCI population, with up to 78% of these individuals experience at least one fall post-rehabilitation [9][10][11].…”

“…Falls can lead to injuries and hospitalization [9], restriction in community participation [10,12,13], and a fear of falling [14]. One of the major factors contributing to falls in this population is the loss of balance [8,13], highlighting the lack of effective postural control in individuals with iSCI. Furthermore, greater postural control in this population is highly related with a more normal gait pattern, higher stride speed, less reliance on supervision or physical assistance, and more functional ambulatory status [2].…”

“…Effective postural control is obtained via the integration of sensory information [7] and the interaction of the body with the changing environment [9]. Due to the sensory and motor impairments at and below the level of the lesion post-SCI [8], sensory reweighting may be affected.…”

“…Quantitative evaluation of postural stability is usually performed using measures based on the displacement of the center-of-pressure (COP) on a force-platform [8] or using measures based on center-of-mass (COM) acceleration from an inertial measurement unit (IMU) on the lower trunk [18,19]. Previous studies have used COP-based measures to investigate limits of stability [8] and the effect of sensory information on postural stability [7] post-SCI. The over-reliance on visual cues while walking and standing due to impaired somatosensation was highlighted [7,16].…”