Role of muscles in lumbar spine stability in maximum extension efforts

Gardner‐Morse, Mack; Stokes, Ian A. F.; Laible, Jeffrey P.

doi:10.1002/jor.1100130521

Cited by 180 publications

(101 citation statements)

References 30 publications

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“…Hypothetical perturbations are applied to the spine in its current configuration to determine if it is stable. From this approach, it became apparent that muscles and the stiffness they provide are essential to maintain spine stability [1][2][3][4]. Not surprisingly, muscle stiffness became linked with stability.…”

Section: Dear Editormentioning

confidence: 99%

Expanding our view of the spine system

Reeves

Cholewicki

2009

Eur Spine J

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Section: Dear Editormentioning

confidence: 99%

Expanding our view of the spine system

Reeves

Cholewicki

2009

Eur Spine J

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“…A number of optimization and EMG driven models have been used to estimate the muscle forces in various lifting conditions. Many of these models do not properly account for the nonlinear passive resistance and/or complex geometry/loading/dynamics (i.e., inertia and damping) of the spine [16,26,35,93]. In addition, many are simplified in not considering dynamic equilibrium equations simultaneously in all directions and at all levels.…”

Section: Introductionmentioning

confidence: 99%

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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“…Several approaches have been taken in previous numerical models for static analysis of the lumbar spine: maximum moment-generating capacity models [7,38], transverse section equilibrium models [36], and stability criterion models [5,10,16]. Experimental measurements of, for instance, electromyographic activities in spinal muscles and Abstract The neutral position of the spine is the posture most commonly sustained throughout daily activities.…”

mentioning

confidence: 99%

Synergy of the human spine in neutral postures

Kiefer

Shirazi‐Adl

Parnianpour

1998

European Spine Journal

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IntroductionAn understanding of mechanisms for the load-resisting capacity of the human spine and load sharing between the passive ligamentous spine and the active muscle tissues in neutral posture is essential for investigation of spinal functioning in normal and pathologic conditions. Several approaches have been taken in previous numerical models for static analysis of the lumbar spine: maximum moment-generating capacity models [7,38], transverse section equilibrium models [36], and stability criterion models [5,10,16]. Experimental measurements of, for instance, electromyographic activities in spinal muscles and Abstract The neutral position of the spine is the posture most commonly sustained throughout daily activities. Previous investigations of the spine focused mainly on maximal exertions in various symmetric and asymmetric postures. This report proposes a new synergetic approach for analysis of the spine in neutral postures and evaluates its performance. The model consists of passive components, the osteoligamentous spine, and active components, the spinal muscles. The muscle architecture includes 60 muscles inserting onto both the rib cage and lumbar vertebral bodies. The passive spine is simulated by a finite element model, while kinematic constraints and optimization are used for resolution of a redundant muscle recruitment problem. Although the passive spine alone exhibits little resistance to a vertical load, its load-bearing capacity in neutral posture is significantly enhanced by the muscles, i.e., the passive spine and its muscles must be considered as a synergetic system. The proposed method is used to investigate the response of the spine when the T1 vertebra displaces 40 mm anteriorly and 20 mm posteriorly from its initial position. The sacrum is fixed at all times and the T1 displacements are achieved by the action of muscles. The results suggest that relatively small muscle activations are sufficient to stabilize the spine in neutral posture under the body weight. The results also indicate that muscles attaching onto the rib cage are important for control of the overall spinal posture and maintenance of equilibrium. The muscles inserting onto the lumbar vertebrae are found mainly to enhance the stability of the spine. The proposed method also predicts forces and moments carried by the passive system. Flexion moments ranging from 8000 Nmm to 15,000 Nmm, corresponding to decreases in lordosis of 6°and 7.5°respectively, are found to be carried by the passive spine at the thoracolumbar junction when the T1 vertebra is 40 mm anterior to its initial position.

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Role of muscles in lumbar spine stability in maximum extension efforts

Cited by 180 publications

References 30 publications

Expanding our view of the spine system

Expanding our view of the spine system

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

Synergy of the human spine in neutral postures

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