Relationship of Seat Interface Pressure to Change in Center of Pressure During Manual Wheelchair Pressure Redistribution Maneuvers

Manual wheelchair users (MWUs) are at high risk of developing pressure injuries (PIs) from prolonged static sitting. Clinical practice guidelines suggest periodic pressure redistribution (PR) to mitigate this risk. Prior work has demonstrated that a wheelchair seat pan instrumented with force sensors can track the change in center of pressure (CoP) as MWUs perform PR and use this measurement to infer the direction and degree of a PR. This study's objective was to quantify the relationship between change in CoP and reduction in seat interface pressure (SIP) under the ischial tuberosities for commonly practiced PR maneuvers. A theoretical model relating SIP and change in CoP for forward leaning PR was developed. Participants performed forward, leftward, and rightward leaning PRs while seated on a pressure mat on the test wheelchair with a load cell-instrumented seat pan. Linear mixed-effects models showed that the relationship of SIP and CoP varies by participant. Across participants, the change in SIP for a given change in CoP was greater with sideways than with forward leans. The type of cushion used did not affect the relationship. These findings can be used as part of her real-time smartphone-based coaching system for PI prevention.