Gilsdorf P, Patterson R, Fisher S, Appel N
Department of Physical Medicine and Rehabilitation, University of Minnesota, Minneapolis 55455.
J Rehabil Res Dev. 1990 Summer;27(3):239-46. doi: 10.1682/jrrd.1990.07.0239.
The effects of back angle and leg height on sitting forces in a wheelchair were studied, using a force plate mounted on a wheelchair seat. Readings of both normal force (perpendicular to the seat) and shear force were measured while the chair's back angle and footrest height were changed. Pressure under the ischial tuberosities was also measured during the footrest height adjustments. Five normal subjects sat directly on the plate as well as upon ROHO and Jay cushions placed on the force plate. Returning the back to the upright position after a recline caused the normal force (+/- SD) to increase 5.4 +/- 2.5, 9.5 +/- 4.0, and 10.0 +/- 2.3 kg for the hard surface, Jay cushion, and ROHO cushion respectively, while shear at the plate increased to 5.1 +/- 2.2, 11.6 +/- 2.6, and 12.3 +/- 2.7 kg for the hard surface, Jay cushion, and ROHO cushion respectively. Leaning forward (away from the back) caused all the forces to return to measurements close to the starting values. The results suggest that the wheelchair user should momentarily lean forward after a recline to reduce undesired forces. If a cushion with firm thigh support is used, ischial tuberosity pressure can be reduced by lowering the leg height as much as possible, which causes a levering action by lifting the pelvis.
使用安装在轮椅座位上的测力板，研究了靠背角度和腿高对轮椅坐姿受力的影响。在改变椅子靠背角度和脚凳高度的同时，测量了法向力（垂直于座位）和剪切力的读数。在调整脚凳高度期间，还测量了坐骨结节下方的压力。五名正常受试者直接坐在测力板上，以及放在测力板上的ROHO和Jay坐垫上。在倾斜后将靠背恢复到直立位置，导致硬表面、Jay坐垫和ROHO坐垫的法向力（±标准差）分别增加5.4±2.5、9.5±4.0和10.0±2.3千克，而测力板上的剪切力分别增加到5.1±2.2、11.6±2.6和12.3±2.7千克。向前倾（远离靠背）使所有力恢复到接近起始值的测量值。结果表明，轮椅使用者在倾斜后应暂时向前倾以减少不必要的力。如果使用具有稳固大腿支撑的坐垫，通过尽可能降低腿高可降低坐骨结节压力，这会通过抬起骨盆产生杠杆作用。
