COMPARATIVE EFFECTS OF POSTURE ON PRESSURE AND SHEAR AT THE BODY-SEAT INTERFACE
COMPARATIVE EFFECTS OF POSTURE ON PRESSURE AND SHEAR AT THE BODY-SEAT INTERFACE
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DOI：
10.1682/jrrd.1992.10.0021
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发表时间：
1992-09-01
影响因子：
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通讯作者：
HOBSON, DA
中科院分区：
文献类型：
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作者：
HOBSON, DA
本研究考虑了坐姿和身体方位对身体-座椅界面处的压力分布和表面剪切（切向）力的影响。研究了轮椅使用者通常采用的九种姿势。在两个研究组内和两个研究组之间进行了比较，两个研究组由12名脊髓损伤（SCI）受试者和10名非残疾受试者组成。在9个可重复的坐姿中，同时测量界面压力和表面剪切力。所有试验均使用相同的座垫。牛津压力监测仪，气动元件装置，用于测量和记录的界面压力。专门为研究构建了用于测量和记录表面剪切力的仪器。分析包括统计学比较的压力值和剪切力的变化，从八个坐姿参考的值记录在一个定义的中立坐姿。压力分布的研究结果表明，在姿势研究SCI科目的最大压力是高于非残疾人的科目在所有的姿势，从6%到46%，这取决于姿势。最大压力可以通过改变姿势来降低：前屈50度，-9%;靠背后仰120度，-12%;全身倾斜，-11%。平均而言，SCI组成员的峰值压力梯度（PPG）比非残疾组高1.5至2.5。PPG的最大降低发生在靠背倾斜120度时，-18%。切向剪切力作用在所有九个姿势研究的身体-座位界面。外推的结果表明，全身倾斜约25度，减少表面剪切力接近零。相比之下，仅靠背倾斜20度导致表面剪切力增加25%。这些结果表明，当使用非残疾受试者作为SCI患者的替代品时必须谨慎，因为这两组之间存在固有的差异。此外，研究人员和临床医生应该认识到，空间中的姿势和身体方向是额外的变量，可以对坐着的人和他或她的支撑表面之间的相互作用产生深远的影响。
This study considers the effects of seated posture and body orientation on the pressure-distribution and surface shear (tangential) forces acting at the body-seat interface. Nine postures typically assumed by wheelchair users were studied. Comparisons were made within and between two study groups, made up of 12 subjects with spinal cord injuries (SCI) and 10 nondisabled subjects. Both interface pressure and the surface shear were measured simultaneously in each of nine reproducible, seated postures. The same seat cushion was used for all trials. The Oxford Pressure Monitor, a pneumatic cell device, was used to measure and record the interface pressures. Instrumentation for measuring and recording the surface shear force was constructed specifically for the study. Analysis consisted of statistically comparing changes in pressure values and shear forces derived from eight sitting postures with reference to values recorded in a defined neutral sitting posture. The pressure-distribution findings suggest that in the postures studied SCI subjects have maximum pressures that are higher than nondisabled subjects in all postures, ranging from 6% to 46% depending on the posture. Maximum pressures can be reduced by postural changes: forward flexion to 50-degrees, - 9%; backrest recline to 120-degrees, - 12%; and, full body tilt, - 11%. On average, the SCI group members have peak pressure gradients (PPG) that are 1.5 to 2.5 greater than the nondisabled group. The maximum reduction in PPG occurred at backrest recline of 120-degrees, - 18%. Tangential shear force acts at the body-seat interface in all nine postures studied. Extrapolation of results suggests that full-body tilt to approximately 25-degrees reduces the surface shear force to near zero. In contrast, a backrest-only recline of 20-degrees causes a 25% increase in the surface shear force. These results suggest that caution must be taken when using nondisabled subjects as surrogates for people with SCI because of the inherent differences between the groups. Also, researchers and clinicians should recognize that posture and body orientation in space are additional variables that can have a profound effect on the interaction between a seated person and his or her supporting surface.