Chair configuration and balance control in persons with spinal cord injury

Objective: To study whether chair configuration influences sitting balance in persons with spinal cord injury (SCI). Design: Cross-sectional group study. Setting: Rehabilitation centers and hospital rehabilitation departments. Patients: Ten complete high thoracic SCI (level T2-T8) patients, 10 complet e low thoracic SCI (T9-T12) patients, and 10 matched able-bodied controls. SCI participants had completed their active rehabilitation at least 6 month s before the study. Interventions: A balance-changing (forward) reaching task while seated in f our differently configured chairs. Tilt angle (7 degrees and 12 degrees) an d reclination angle (22 degrees) were varied relative to a standard chair c onfiguration (10 degrees reclination). Main Outcome Measures: Maximal unsupported reaching distance, center-of-pre ssure displacement and muscle activity. Results: Although no significant difference in actively controllable reach was found in controls or in subjects with low SCI, sitting balance improved in all chairs relative to the standard chair. Ability to control displacem ent of arms and trunk during reaching improved. No apparent need for additi onal postural muscle activity was found. Persons with high SCI did not impr ove their sitting balance. They were unable to control a shift in body mass larger than the one induced by arm movement. However, they had less muscle activity after backrest reclination or tilting the chair backwards. Conclusions: The tested chairs had an overall positive effect. However, for individually tailored chair configurations factors other than those invest igated should be considered.