Related Experiment Video
Updated: Mar 21, 2026

A Teleoperated Robotic System-Assisted Percutaneous Transiliac-Transsacral Screw Fixation Technique
Published on: January 6, 2023
Orthotic-Style Off-Loading Wheelchair Seat Cushion Reduces Interface Pressure Under Ischial Tuberosities and
Barbara Crane1, Michael Wininger2, Evan Call3
1Department of Rehabilitation Sciences, University of Hartford, West Hartford, CT.
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.
Related Concept Videos
Spinal Nerves: Plexus II
The Lumbar Plexus
The lumbar plexus is situated within the lumbar region of the back and is primarily formed by the first four lumbar spinal nerves (L1 to L4). This plexus extends its branches into several nerves, including the...
Inflammatory Bowel Disease V: Surgical Management
Here are some common surgical interventions for IBD:
Muscles of the Pelvic Floor and Perineum
Perineal Layer
The perineum is a diamond-shaped area below the pelvic diaphragm, divided into an anterior urogenital triangle that contains the external genitals and a posterior anal triangle housing the anus. The urogenital...

