Spinal Load and Stability during Pushing

描述：腰背部疾病(LBD)是导致工作日减少的主要原因，也是当今工业界面临的最昂贵的职业安全和健康问题。工业MMH的性质正在迅速从举重向推拉式工作转变。流行病学研究确定推拉是LBD的主要风险因素，即20%的伤害。不幸的是，关于工业推力任务的生物力学风险知之甚少。腰椎退行性变的生物力学风险包括脊柱负荷、脊柱稳定性和材料耐受性，如椎间盘和脊柱骨折极限。初步计算表明，在用力过程中，脊柱的稳定性受到严重限制，因此需要增加肌肉的协同收缩。众所周知，联合收缩会增加脊柱负荷。此外，推力预计会增加脊柱剪切力的风险。很少有已发表的研究检查推力作用下的脊柱负荷，没有考虑共同激活的影响，很少考虑剪切负荷，也没有考虑脊柱稳定性。这项工作的目标是量化推力任务施加的生物力学风险因素。我们将对推力工作进行多机构生物力学分析，包括体内脊柱压缩、脊柱剪切力和脊柱稳定性的评估。在具体目标#1中，我们将校准肌电辅助的脊柱负荷模型，以便能够分析推力。初步数据显示，在推举任务中，躯干肌肉的协同收缩大幅增加。该模型在确定脊柱负荷时考虑了躯干肌肉的共同收缩，并允许估计脊柱剪切力。校准和验证程序将包括躯干屈曲和伸展运动的实验比较。共同收缩增加表明推力任务与脊柱稳定性降低有关。在具体目标#2中，我们将校准并进一步发展脊柱稳定性模型，以允许分析推力，包括动态稳定性的评估。这一过程将包括在屈曲和伸展力矩条件下突然扰动后对躯干运动学、动力学和肌电的实验测量。在具体目标#3中，我们将评估工作场所因素对脊柱压缩、剪切力和稳定性的影响。实验将记录推力和手柄高度对脊柱生物力学的影响。在第二个实验中，我们将检验手柄稳定性如何影响生物力学风险。第三个实验将评估用力动力学对生物力学风险的影响，即被推物体的惯性质量、运动速度的影响，并比较推车和推顶升降机辅助装置时的脊柱负荷和稳定性。

DESCRIPTION: Low-back disorders (LBDs) are the leading cause of lost work days and the most costly occupational safety and health problem facing industry today. The nature of industrial MMH has been rapidly changing from lifting to push-pull exertions. Epidemiological studies identify pushing and pulling as a major LBD risk factor, i.e. 20% of injuries. Unfortunately, little is known regarding biomechanics risks of industrial pushing tasksBiomechanical risk of LBD includes components of spinal load, spinal stability and material tolerances such as disc and vertebral fracture limits. Preliminary calculations suggest spinal stability is severely limited during pushing exertions thereby requiring increased muscle co-contraction. Co-contraction is known to increase spinal loads. Moreover, push forces are expected to introduce increased risk from spinal shear forces. Few published studies have examined spinal load during pushing exertions, NONE have considered the influence of coactivation, few have considered shear load and NONE have considered spinal stability. The goal of this effort is to quantify the biomechanical risk factors imposed by pushing tasksWe will perform a multi-institutional biomechanical analyses of pushing exertions including in-vivo assessment of spinal compression, spinal shear force and spinal stability. In Specific Aim #1 we will calibrate the EMG-assisted model of spinal load to permit analysis of pushing exertions. Preliminary data indicate large increases in trunk muscle co-contraction during pushing versus lifting tasks. This model accounts for trunk muscle co-contraction in the determination of spinal load and permits estimation of spinal shear force. The calibration and validation procedure will include experimental comparison of trunk flexion versus extension exertions. Increased co-contraction indicates the pushing tasks are associated with reduced spinal stability. In Specific Aim #2 we will calibrate and further develop the spinal stability model to permit analyses of pushing exertions including assessment of dynamic stability. This process will include experimental measurement of trunk kinematics, kinetics and EMG following sudden perturbations in both flexion and extension moment conditions. In Specific Aim #3 we will evaluate the influence of workplace factors on spinal compression, shear force and stability. Experimental will record the influence of push force and handle height on spine biomechanics. In a second experiment we will examine how handle stability influences biomechanical risk. A third experiment will evaluate the influence of exertion dynamics on biomechanical risk, i.e. the influence of the inertial mass of the pushed object, the velocity of movement, and compare the spinal loads and stability of pushing a cart versus pushing an overhead lift-assist device.