The effect of seat tilting on pelvic position, balance control, and compensatory postural muscle use in paraplegic subjects

Objective: To study the effect of seat tilting on pelvic tilt, balance control, and postural muscle use in persons with a thoracic spinal cord injury (SCI). Design: Cross-sectional group study. Setting: Rehabilitation centers and rehabilitation hospital departments. Patients: Ten complete high thoracic SCI (level T2-8) patients, 10 complete low thoracic SCI (level T9-12) patients, and 10 matched able-bodied controls. Intervention: A 10 degrees forward inclination of the seat. Main Outcome Measures: Pelvic tilt, center of pressure displacement, and muscle activity. Results: Anterior tilting of the pelvis as a result of forward inclination of the seat could not be shown, either in persons with or without SCI. Balance control was not influenced by forward inclination of the seat. Participants' overall muscle activity decreased while they were seated in the chair with the forwardly inclined seat. Conclusions: Evidence provided by the kinematic and electromyographic data is not sufficient to develop a protocol for wheelchair prescription on the basis of pelvic positioning.