Effect of Tilt-in-Space and Reclining Angles of Wheelchairs on Normal Force and Shear Force in the Gluteal Region.

Healthcare workers need to educate patients regarding proper sitting positions to prevent pressure injuries in the elderly and disabled. The purpose of this study was to investigate the differences in normal and shear force in the gluteal region using the combination of tilt-in-space and reclining functions of wheelchairs. Twelve healthy subjects were recruited. Protocols for 15 wheelchair tilt-in-space and reclining angles, including three reclining angles (0°, 10°, and 20°) and five tilt-in-space (0°, 5°, 10°, 15°, and 20°), were randomly assigned. To measure the amount of normal and shear force applied to the gluteal region while sitting on a wheelchair, a force plate was placed on the seat to measure the seat reaction force. For statistical analysis, a two-factor analysis of variance, with tilt-in-space and reclining, was performed for each normal and shear force. The normal force showed a significant decrease with increased reclining angle. For the shear force combined with sagittal and lateral components, the 10° tilt-in-space showed a significant decrease compared to other conditions. The combination of 20° reclining and 10° tilt-in-space angles may decrease both normal and shear force in the gluteal region while sitting. These findings may help wheelchair-dependent individuals avoid pressure injuries.