Vertical ground reaction force-based analysis of powered exoskeleton-assisted walking in persons with motor-complete paraplegia.

OBJECTIVE: To use vertical ground reaction force (vGRF) to show the magnitude and pattern of mechanical loading in persons with spinal cord injury (SCI) during powered exoskeleton-assisted walking. RESEARCH DESIGN: A cross-sectional study was performed to analyze vGRF during powered exoskeleton-assisted walking (ReWalk™: Argo Medical Technologies, Inc, Marlborough, MA, USA) compared with vGRF of able-bodied gait. SETTING: Veterans Affairs Medical Center. PARTICIPANTS: Six persons with thoracic motor-complete SCI (T1-T11 AIS A/B) and three age-, height-, weight- and gender-matched able-bodied volunteers participated. INTERVENTIONS: SCI participants were trained to ambulate over ground using a ReWalk™. vGRF was recorded using the F-Scan™ system (TekScan, Boston, MA, USA). OUTCOME MEASURES: Peak stance average (PSA) was computed from vGRF and normalized across all participants by percent body weight. Peak vGRF was determined for heel strike, mid-stance, and toe-off. Relative linear impulse and harmonic analysis provided quantitative support for analysis of powered exoskeletal gait. RESULTS: Participants with motor-complete SCI, ambulating independently with a ReWalk™, demonstrated mechanical loading magnitudes and patterns similar to able-bodied gait. Harmonic analysis of PSA profile by Fourier transform contrasted frequency of stance phase gait components between able-bodied and powered exoskeleton-assisted walking. CONCLUSION: Powered exoskeleton-assisted walking in persons with motor-complete SCI generated vGRF similar in magnitude and pattern to that of able-bodied walking. This suggests the potential for powered exoskeleton-assisted walking to provide a mechanism for mechanical loading to the lower extremities. vGRF profile can be used to examine both magnitude of loading and gait mechanics of powered exoskeleton-assisted walking among participants of different weight, gait speed, and level of assist.

Adaptation of computerized posturography to assess seated balance in persons with spinal cord injury.

BACKGROUND: The ability to retain or improve seated balance function after spinal cord injury (SCI) may mean the difference between independence and requiring assistance for basic activities of daily living. Compared with assessments of standing and walking balance, seated balance assessments remain relatively underemphasized and under-utilized. OBJECTIVE: To optimize tools for assessing seated balance deficits and recovery in SCI. DESIGN: Cross-sectional observational study of different methods for assessing seated balance function. SETTING: Veterans Affairs Center of Excellence for the Medical Consequences of Spinal Cord Injury. PARTICIPANTS: Seven able-bodied volunteers, seven participants with chronic motor-complete thoracic SCI. INTERVENTIONS: A computerized pressure-plate apparatus designed for testing standing balance was adapted into a seated balance assessment system. OUTCOME MEASURES: Seated section of Berg Balance Scale; modified functional reach test; and two posturography tests: limits of stability and clinical test of sensory integration on balance. RESULTS: Seated posturography demonstrated improved correlation with neurological level of lesion compared to that of routinely applied subjective clinical tests. CONCLUSION: Seated posturography represents an appealing outcome measure that may be applied toward the measurement of functional changes in response to various rehabilitation interventions in individuals with paralysis.