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Predictive equations for lumbar spine loads in load-dependent asymmetric one- and two-handed lifting activities

Arjmand, N ; Sharif University of Technology | 2012

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  1. Type of Document: Article
  2. DOI: 10.1016/j.clinbiomech.2011.12.015
  3. Publisher: 2012
  4. Abstract:
  5. Background: Asymmetric lifting activities are associated with low back pain. Methods: A finite element biomechanical model is used to estimate spinal loads during one- and two-handed asymmetric static lifting activities. Model input variables are thorax flexion angle, load magnitude as well as load sagittal and lateral positions while response variables are L4-L5 and L5-S1 disc compression and shear forces. A number of levels are considered for each input variable and all their possible combinations are introduced into the model. Robust yet user-friendly predictive equations that relate model responses to its inputs are established. Findings: Predictive equations with adequate goodness-of-fit (R 2 ranged from ~ 94% to 99%, P ≤ 0.001) that relate spinal loads to task (input) variables are established. Contour plots are used to identify combinations of task variable levels that yield spine loads beyond the recommended limits. The effect of uncertainties in the measurements of asymmetry-related inputs on spinal loads is studied. Interpretation: A number of issues regarding the NIOSH asymmetry multiplier are discussed and it is concluded that this multiplier should depend on the trunk posture and be defined in terms of the load vertical and horizontal positions. Due to an imprecise adjustment of the handled load magnitude this multiplier inadequately controls the biomechanical loading of the spine. Ergonomists and bioengineers, faced with the dilemma of using either complex but more accurate models on one hand or less accurate but simple models on the other hand, have hereby easy-to-use predictive equations that quantify spinal loads under various occupational tasks
  6. Keywords:
  7. Asymmetric lifting ; Ergonomics ; Predictive equation ; Asymmetric lifting ; Biomechanical loading ; Biomechanical model ; Compression and shear ; Contour plot ; Finite Element ; Goodness of fit ; Input variables ; Load magnitude ; Lumbar spines ; Model inputs ; Model response ; Occupational tasks ; Predictive equations ; Response surface methodology ; Spinal loads ; Trunk postures ; Finite element method ; Loading ; Uncertainty analysis ; Loads (forces) ; Human ; Intervertebral disk ; kinematics ; Load carrying capacity ; Low back pain ; Lumbar spine ; One hand lifting ; Physical activity ; Priority journal ; Two hand lifting ; Algorithms ; Biomechanics ; Finite Element Analysis ; Humans ; Intervertebral Disc ; Lifting ; Lumbar Vertebrae ; Models, Biological ; Posture ; Pressure ; Regression Analysis ; Shear Strength ; Spine ; Stress, Mechanical ; Weight-Bearing
  8. Source: Clinical Biomechanics ; Volume 27, Issue 6 , 2012 , Pages 537-544 ; 02680033 (ISSN)
  9. URL: http://www.clinbiomech.com/article/S0268-0033%2811%2900329-9/abstract