title: Use of weight-bearing MRI for evaluating wheelchair cushions based on internal soft-tissue deformations under ischial tuberosities.
abstract: 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.
authors.affiliation: Department of Diagnostic Imaging, Sheba Medical Center, Tel Hashomer, Israel.
authors.forename: Nogah
authors.initials: N
authors.lastname: Shabshin
authors.forename: Gil
authors.initials: G
authors.lastname: Zoizner
authors.forename: Amir
authors.initials: A
authors.lastname: Herman
authors.forename: Vlad
authors.initials: V
authors.lastname: Ougortsin
authors.forename: Amit
authors.initials: A
authors.lastname: Gefen
mesh_terms: D000273:Adipose Tissue / Q000503:physiopathology; D000328:Adult; D002081:Buttocks / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology; D011312:Pressure; D003668:Pressure Ulcer / Q000503:physiopathology* / Q000517:prevention & control; D011482:Protective Devices; D055682:Viscoelastic Substances; D016474:Weight-Bearing; D014910:Wheelchairs
chemical_list: D055682:Viscoelastic Substances