Reducing Low-back Disorders Using a New Sitting Design

描述：工作相关的下背部肌肉骨骼疾病是常见的，影响了大部分的劳动力。腰痛的职业风险因素包括持续的静态肌肉负荷，以及脊柱和骨盆的不适当弯曲/位置。坐着可能会导致骨盆后旋，腰椎前凸减少，肌肉活动和椎间盘压力的变化，坐骨和尾骨压力过大，当然还有相关的LBP。研究了一种新型座椅设计，其中座椅后部（BPS）可以相对于座椅前部（FPS）动态地向下和向上倾斜，提供大腿和坐骨支撑的调节，并且背部支撑的高度和体积可以调节。在初步研究中发现，BPS降低时的坐姿和腰部支撑的调整导致接触压力分布更均匀，坐骨下的峰值压力降低，总腰椎前凸和节段腰椎前凸增加，骨盆向前旋转，腰椎椎间高度增加。我们认为，座椅和靠背的功能关系需要进一步研究，以便不仅防止腰椎变平，而且减少长期坐着时坐骨负荷，这与LBP有关。我们建议研究新的坐姿概念的生物力学和神经肌肉效应，并定量评估LBP患者使用适当的腰部支撑的益处，增加脊柱前凸，减少坐骨结节所承受的坐姿压力和负荷。 假设1：当BPS向下倾斜时，坐骨结节和腰椎上的负荷将减少并分别转移到大腿和胸椎。下背部肌肉活动也会减少。 具体目标1：在有和没有坐骨支撑的情况下，结合平坦或可调节的背部支撑，将评估臀部-大腿和座椅之间以及背部和靠背之间的接触压力分布，以及座椅和靠背处承载的载荷。将研究在这些条件下稳定躯干所涉及的肌肉活动。 假设二：当BPS向下倾斜以减少坐骨支撑时，将观察到腰椎前凸增加、骨盆向前旋转和椎间高度增加。具体目标2：将使用X射线图像测量腰椎的总体和节段性腰椎前凸、骨盆倾斜度和椎间隙，并在不同坐姿条件下进行比较。 假设三：在BPS处于水平和向下倾斜位置的姿势之间交替坐着将减少与坐着相关的不适/疼痛。因此，LBP患者可以更好地忍受长时间的坐姿。具体目标3：在两组有疼痛史和症状的慢性LBP患者中使用问卷调查，评价使用这种坐姿设计4个月的主观评价和印象。

DESCRIPTION: Work-related low back musculoskeletal disorders are common and affect a large portion of the workforce. Occupational risk factors for LBP include sustained static muscle load, and inappropriate curvature/position of the spine and pelvis. Sitting may cause backward rotation of the pelvis, reduction in lumbar lordosis, changes in muscle activities and disc pressure, excessive pressure over the ischium and coccyx, and certainly the associated LBP. A new seat design, of which the back part of seat (BPS) can be dynamically tilted downward and upward with respect to the front part of the seat (FPS) providing adjustment of thigh and ischial support and the back support is adjustable in height and volume, will be investigated. It was found in the pilot study that sitting with lowered BPS and adjustment of low back support resulted in more evenly distributed contact pressure, reduced peak pressure under the ischia, increased total and segmental lumbar lordosis, forwardly rotated the pelvis, and increased lumbar intervertebral heights. We believe that the functional relations of the seat and backrest need to be further investigated in order to not only prevent flattening of the lumbar spine but also reduce the ischial load in long term sitting, which are related to LBP. We propose to study the biomechanical and neuromuscular effects of the new sitting concept, and evaluate quantitatively the benefits in the LBP patients for using appropriate lumbar support that increases lordosis and decreases the sitting pressure and load carried by the ischial tuberosities. Hypothesis 1: When the BPS is tilted downward, load on the ischial tubercles and lumbar spine will be reduced and shifted to the thighs and the thoracic spine, respectively. Low back muscle activities will also be reduced. Specific aim 1: Contact pressure distributions between the buttock-thighs and seat, and between the back and backrest, load carried at the seat and back will be evaluated with and without ischial support, combined with flat or adjusted back support. The muscular activities involved in stabilizing the trunk under these conditions will be investigated. Hypothesis 2: Increase in lumbar lordosis, forward rotation of the pelvis, and larger intervertebral heights will be observed when the BPS is tilted down to reduce ischial support. Specific aim 2: The total and segmental lumbar lordosis, pelvis inclination, and intervertebral spaces of lumbar spine, will be measured using X-ray images and compared under the different sitting conditions. Hypothesis 3: Sitting alternately between the postures with the BPS at level and tilted down positions will reduce the discomfort/pain associated with sitting. As a result, patients with LBP will better tolerate prolonged sitting. Specific aim 3: The subjective evaluation and impressions gained from the use of such a sitting design for a period of four months will be evaluated using questionnaire in two groups of chronic LBP patients with pain history and symptoms.