Relationship between asymmetrical sciatic pressure and buttocks shear forces during usage of wheelchair with reclining function

Abstract

The purpose of this study was to clarify the relationship between asymmetrical sciatic support, seat posture angle, and buttocks shear forces during usage of reclining wheelchairs. Participants included 11 healthy adult men (20.8 ± 0.6 years old). There were no left-right differences in sciatic pressures (no difference) for control conditions. Cushions with different left-right thicknesses were applied to create sciatic pressure asymmetries (difference) in the experimental condition. A shear force was then applied to the buttocks under each condition. Measurements were performed on the right and left girth during the return to an upright position (RUP) from a starting position in which the back-support was reclined. The initial upright position (IUP) was 10 degrees vertical from the original position. The shear force applied to the buttocks was measured and the rate of change was calculated based on the initial value determined during the IUP. As a result, the left side gluteal displacement force change rate was significantly higher under difference (experimental) conditions. These findings suggest that when a reclining wheelchair is used, asymmetrical sciatic support exacerbates the relationship between higher seat pressures, adding more significant shear forces to the buttocks.