Shabshin Nogah, Zoizner Gil, Herman Amir, Ougortsin Vlad, Gefen Amit
Department of Diagnostic Imaging, Sheba Medical Center, Tel Hashomer, Israel.
J Rehabil Res Dev. 2010;47(1):31-42. doi: 10.1682/jrrd.2009.07.0105.
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.
深部组织损伤（DTI）是一种严重的压疮类型，其损伤起始于完整皮肤之下，由承重骨隆突导致机械变形的软组织中。坐姿导致的DTI通常发生在臀肌，臀肌会因承重的坐骨结节（ITs）而持续变形。目前尚无测量内部组织变形的临床方法；因此，轮椅坐垫的设计和选择主要基于测量坐姿压力。我们的目标是使用承重磁共振成像（MRI）评估不同商用坐垫对ITs下方内部软组织变形的影响。我们特别比较了受试者（n = 10）坐在四个坐垫（两个粘弹性坐垫和两个泡沫坐垫）上以及直接坐在刚性支撑物上时肌肉、皮下脂肪和有效（肌肉和脂肪一起）组织的变形情况。肌肉组织中的变形最大（平均约70%），是脂肪中变形量（约30%）的两倍。有效的软组织变形约为50%至约60%。尽管坐垫能使肌肉变形轻微降低约10%，但从理论上讲，我们的解释表明这种变形水平能增加安全坐姿时间。本研究表明，承重MRI适用于评估轮椅坐垫，并且在未来可能成为系统支持坐垫设计和选择的一种工具。
