Effect of seat inclination on seated pressures of individuals with spinal cord injury.

Background And Purpose: Manual wheelchair configurations commonly include "squeezing" the wheelchair frame to improve balance for users with spinal cord injuries. This squeezing is achieved by lowering the rear portion of the seat relative to the front of the seat while maintaining the same back angle. The study's purpose was to examine the effect of increasing posterior seat inclination on buttock interface pressures.

Subjects: Nine male and 5 female subjects (mean age=37 years, SD=11.2, range=19-55) with complete thoracic or lumbar spinal cord injury were tested.

Methods: Subjects sat on a pressure mat placed over a foam cushion. Pressure readings were taken at seat angles reflecting seat height decreases of 0, 5.1, 7.6, and 10.2 cm (0, 2, 3, and 4 in) of the rear of the seat relative to the front of the seat. An analysis of variance and a Duncan multiple range test were used for data analysis.

Results: No meaningful differences were found in measurements of interface pressure (dispersion index, contact area, and seat pressure index), total force on seat, or peak pressure index with posterior seat inclination.

Discussion And Conclusion: The data indicate no meaningful evidence that squeezing a wheelchair frame increases seat interface pressures.