Orthotic-Style Off-Loading Wheelchair Seat Cushion Reduces Interface Pressure Under Ischial Tuberosities and Sacrococcygeal Regions

Objective: To assess the efficacy of an off-loading wheelchair seat cushion in removing pressure from high-risk ischial tuberosities and the coccyx/sacrum in wheelchair sitting.

Design: Repeated-measures design.

Setting: Private research laboratory.

Participants: Manual wheelchair users with chronic spinal cord injuries (N=10).

Interventions: Three configurations of an off-loading wheelchair seat cushion compared with a flotation style (10-cm air inflation) wheelchair seat cushion.

Main outcome measures: Outcome measures included peak pressure index (PPI), ischial tuberosity peak pressures, and the dispersion index or ratio of pressures under the ischial and sacral regions to the total of all pressures recorded.

Results: PPI and ischial tuberosities peak pressure ranged from a low of 39±18 and 68±46mmHg in the fully off-loaded cushion to a high of 97±30 and 106±34mmHg, respectively, for the flotation style cushion (2-way analysis of variance main effect across 4 conditions, P<.001). Dispersion index ranged from a low of 8%±3% in the fully off-loaded cushion to a high of 16%±3% in the flotation style cushion. Pairwise comparisons yielded significance in all cushion-pair analyses (P<.05 after multiple corrections).

Conclusions: The force-removal approach of this orthotic off-loading cushion design effectively reduces a known extrinsic risk factor for pressure ulcers-interface pressure-in the high-risk ischial tuberosity and sacral/coccygeal regions of the buttocks.