Spinal muscle forces, internal loads and stability in standing under various postures and loads—application of kinematics-based algorithm

Shirazi‐Adl, A.; El‐Rich, Marwan; Pop, D.; Parnianpour, Mohamad

doi:10.1007/s00586-004-0779-0

Cited by 80 publications

(53 citation statements)

References 54 publications

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“…A sagittally symmetric T1-S1 beam-rigid body model made of six deformable beams to represent T12-S1 discs and seven rigid elements to represent T1-T12 (as a single body) and lumbosacral (L1-S1) vertebrae was used [6,8,30,89]. The beams modeled the overall nonlinear stiffness of T12-S1 motion segments (i.e., vertebrae, disc, facets and ligaments) at different directions and levels.…”

Section: Thoracolumbar Finite Element Modelmentioning

confidence: 99%

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Analysis of squat and stoop dynamic liftings: muscle forces and internal spinal loads

2006

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Despite the well-recognized role of lifting in back injuries, the relative biomechanical merits of squat versus stoop lifting remain controversial. In vivo kinematics measurements and model studies are combined to estimate trunk muscle forces and internal spinal loads under dynamic squat and stoop lifts with and without load in hands. Measurements were performed on healthy subjects to collect segmental rotations during lifts needed as input data in subsequent model studies. The model accounted for nonlinear properties of the ligamentous spine, wrapping of thoracic extensor muscles to take curved paths in flexion and trunk dynamic characteristics (inertia and damping) while subject to measured kinematics and gravity/ external loads. A dynamic kinematics-driven approach was employed accounting for the spinal synergy by simultaneous consideration of passive structures and muscle forces under given posture and loads. Results satisfied kinematics and dynamic equilibrium conditions at all levels and directions. Net moments, muscle forces at different levels, passive (muscle or ligamentous) forces and internal compression/shear forces were larger in stoop lifts than in squat ones. These were due to significantly larger thorax, lumbar and pelvis rotations in stoop lifts. For the relatively slow lifting tasks performed in this study with the lowering and lifting phases each lasting~2 s, the effect of inertia and damping was not, in general, important. Moreover, posterior shift in the position of the external load in stoop lift reaching the same lever arm with respect to the S1 as that in squat lift did not influence the conclusion of this study on the merits of squat lifts over stoop ones. Results, for the tasks considered, advocate squat lifting over stoop lifting as the technique of choice in reducing net moments, muscle forces and internal spinal loads (i.e., moment, compression and shear force).

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Section: Thoracolumbar Finite Element Modelmentioning

confidence: 99%

“…The kinematics-based approach that results in a synergistic solution of the active/passive system has already been successfully applied to isometric conditions in upright [30,89] and flexed postures [8]. The objectives of this work are, hence, set as follows.…”

Section: Introductionmentioning

confidence: 99%

Analysis of squat and stoop dynamic liftings: muscle forces and internal spinal loads

2006

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“…While the in vivo investigation of intervertebral loading is still problematical, kinematic studies are becoming more common [16]. The lumbar spine is a kinetic chain that requires the sharing of motion between levels during bending.…”

Section: Introductionmentioning

confidence: 99%

Uneven intervertebral motion sharing is related to disc degeneration and is greater in patients with chronic, non-specific low back pain: an in vivo, cross-sectional cohort comparison of intervertebral dynamics using quantitative fluoroscopy

Breen

2017

Eur Spine J

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“…If this force passes close to the centroid of the vertebrae, it ensures that shear and bending moments are small [14] and if it lies within the vertebrae it ensures stability. Although models for the spine have become increasingly sophisticated [15][16][17][18], only some consider posture [15,16,19] and many do not take into account the actual curvature of individual spines.…”

Section: Introductionmentioning

confidence: 99%

The lumbar spine has an intrinsic shape specific to each individual that remains a characteristic throughout flexion and extension

et al. 2014

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Purpose We have previously shown that the lumbar spine has an intrinsic shape specific to the individual and characteristic of sitting, standing and supine postures. The purpose of this study was to test the hypothesis that this intrinsic shape is detectable throughout a range of postures from extension to full flexion in healthy adults. Methods Sagittal images of the lumbar spine were taken using a positional MRI with participants (n = 30) adopting six postures: seated extension, neutral standing, standing with 30, 45 and 60°and full flexion. Active shape modelling (ASM) was used to identify and quantify 'modes' of variation in the shape of the lumbar spine. Results ASM showed that 89.5 % of the variation in the shape of the spine could be explained by the first two modes; describing the overall curvature and the distribution of curvature of the spine. Mode scores were significantly correlated between all six postures (modes 1-9, r = 0.4-0.97, P \ 0.05), showing that an element of intrinsic shape was maintained when changing postures. The spine was most even in seated extension (P \ 0.001) and most uneven between 35 and 45°flexion (P \ 0.05). Conclusions This study shows that an individual's intrinsic lumbar spine shape is quantifiable and detectable throughout lumbar flexion and extension. These findings will enable the role of lumbar curvature in injury and low back pain to be assessed in the clinic and in the working and recreational environments.

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Spinal muscle forces, internal loads and stability in standing under various postures and loads—application of kinematics-based algorithm

Cited by 80 publications

References 54 publications

Analysis of squat and stoop dynamic liftings: muscle forces and internal spinal loads

Analysis of squat and stoop dynamic liftings: muscle forces and internal spinal loads

Uneven intervertebral motion sharing is related to disc degeneration and is greater in patients with chronic, non-specific low back pain: an in vivo, cross-sectional cohort comparison of intervertebral dynamics using quantitative fluoroscopy

The lumbar spine has an intrinsic shape specific to each individual that remains a characteristic throughout flexion and extension

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