Periodically relieving ischial sitting load to decrease the risk of pressure ulcers.

Objective: To investigate the relieving effect on interface pressure of an alternate sitting protocol involving a sitting posture that reduces ischial support.

Design: Repeated measures in 2 protocols on 3 groups of subjects.

Setting: Laboratory.

Participants: Twenty able-bodied persons, 20 persons with paraplegia, and 20 persons with tetraplegia.

Interventions: Two 1-hour protocols were used: alternate and normal plus pushup. In the alternate protocol, sitting posture was alternated every 10 minutes between normal (sitting upright with ischial support) and with partially removed ischial support (WO-BPS) postures; in the normal plus pushup protocol, sitting was in normal posture with pushups (lifting the subject off the seat) performed every 20 minutes.

Main Outcome Measure: Interface pressure on seat and backrest.

Results: In WO-BPS posture, the concentrated interface pressure observed around the ischia in normal posture was significantly repositioned to the thighs. By cyclically repositioning the interface pressure, the alternate protocol was superior to the normal plus pushup protocol in terms of a significantly lower average interface pressure over the buttocks.

Conclusions: A sitting protocol periodically reducing the ischial support helps lower the sitting load on the buttocks, especially the area close to ischial tuberosities.