Article

Deep tissue injury (DTI) is a severe type of pressure ulcer, in which damage
initiates under intact skin, in soft tissues that are mechanically deformed by
load-bearing bony prominences. Sitting-acquired DTI typically occurs in the
gluteus muscles that could sustain deformations by the weight-bearing ischial
tuberosities (ITs). No clinical method currently exists for measuring internal
tissue deformations; so design and selection of wheelchair cushions are based
mostly on measuring sitting pressures. Our objective was to evaluate the
influence of different commercial cushions on internal soft-tissue deformations
under the ITs, using weight-bearing magnetic resonance imaging (MRI). We
specifically compared muscle, superficial fat, and effective (muscle and fat
together) tissue deformations while subjects (n = 10) sat on four cushions (two
viscoelastic and two foam) and directly on a rigid support. Deformations were
maximal in muscle tissue (mean approximately 70%), twice more the amount than in
fat (approximately 30%). Effective soft-tissue deformations were approximately
50% to approximately 60%. Although cushions mildly reduced muscle deformations in
the order of 10%, theoretically, our interpretation suggests that this
deformation level adds safe sitting time. This study demonstrated that
weight-bearing MRI is applicable for evaluating wheelchair cushions and, in the
future, may be a tool to systematically support cushion design and selection.

Langue : ANGLAIS