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Musculoskeletal Modeling of the Lumbar Spine to Explore Functional Interactions between Back Muscle Loads and Intervertebral Disk Multiphysics.

Toumanidou T, Noailly J - Front Bioeng Biotechnol (2015)

Bottom Line: Calculations led to intradiscal pressure values within ranges of values measured in vivo.Our simulations pointed out a likely existence of a functional balance between stretch-induced muscle activation and IVD multiphysics toward improved mechanical stability of the lumbar spine understanding.This balance suggests that proper night rest contributes to mechanically strengthen the spine during day activity.

View Article: PubMed Central - PubMed

Affiliation: Institute for Bioengineering of Catalonia , Barcelona , Spain ; Department of Information and Communication Technologies, Universitat Pompeu Fabra , Barcelona , Spain.

ABSTRACT
During daily activities, complex biomechanical interactions influence the biophysical regulation of intervertebral disks (IVDs), and transfers of mechanical loads are largely controlled by the stabilizing action of spine muscles. Muscle and other internal forces cannot be easily measured directly in the lumbar spine. Hence, biomechanical models are important tools for the evaluation of the loads in those tissues involved in low-back disorders. Muscle force estimations in most musculoskeletal models mainly rely, however, on inverse calculations and static optimizations that limit the predictive power of the numerical calculations. In order to contribute to the development of predictive systems, we coupled a predictive muscle model with the passive resistance of the spine tissues, in a L3-S1 musculoskeletal finite element model with osmo-poromechanical IVD descriptions. The model included 46 fascicles of the major back muscles that act on the lower spine. The muscle model interacted with activity-related loads imposed to the osteoligamentous structure, as standing position and night rest were simulated through distributed upper body mass and free IVD swelling, respectively. Calculations led to intradiscal pressure values within ranges of values measured in vivo. Disk swelling led to muscle activation and muscle force distributions that seemed particularly appropriate to counterbalance the anterior body mass effect in standing. Our simulations pointed out a likely existence of a functional balance between stretch-induced muscle activation and IVD multiphysics toward improved mechanical stability of the lumbar spine understanding. This balance suggests that proper night rest contributes to mechanically strengthen the spine during day activity.

No MeSH data available.


Related in: MedlinePlus

(A) Right sagittal, (B) back, and (C) top transverse views of the 46-muscle L3–S1 finite element model: Iliocostalis (IL) and Longissimus Thoracis pars Lumborum (LTpL), Longissimus Thoracis pars Thoracis (LTpTh), Multifidus (MF), Psoas (PS).
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Figure 1: (A) Right sagittal, (B) back, and (C) top transverse views of the 46-muscle L3–S1 finite element model: Iliocostalis (IL) and Longissimus Thoracis pars Lumborum (LTpL), Longissimus Thoracis pars Thoracis (LTpTh), Multifidus (MF), Psoas (PS).

Mentions: The LTpL and the IL were modeled with three and two symmetric fascicle pairs, respectively (Figure 1). The LTpTh was modeled with four symmetric fascicles with caudal insertions at the L3–L5 vertebrae and cranial insertions reconstructed to simulate the lines of action that virtually reach the T3–T6 levels of the thorax. We assumed a common rostral insertion of these cranial ends at the dorsal part of the third rib, represented as an enlarged transverse process of the third thoracic vertebra and modeled as a rigid rod. In simulated standing, this thoracic insertion was assumed to be cranio-caudally aligned with the uppermost vertebral level of the model, i.e., L3. A common musculotendon rest length was assumed for all thoracic elements based on the lumbar musculoskeletal RB model implemented by Christophy et al. (2012).


Musculoskeletal Modeling of the Lumbar Spine to Explore Functional Interactions between Back Muscle Loads and Intervertebral Disk Multiphysics.

Toumanidou T, Noailly J - Front Bioeng Biotechnol (2015)

(A) Right sagittal, (B) back, and (C) top transverse views of the 46-muscle L3–S1 finite element model: Iliocostalis (IL) and Longissimus Thoracis pars Lumborum (LTpL), Longissimus Thoracis pars Thoracis (LTpTh), Multifidus (MF), Psoas (PS).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525063&req=5

Figure 1: (A) Right sagittal, (B) back, and (C) top transverse views of the 46-muscle L3–S1 finite element model: Iliocostalis (IL) and Longissimus Thoracis pars Lumborum (LTpL), Longissimus Thoracis pars Thoracis (LTpTh), Multifidus (MF), Psoas (PS).
Mentions: The LTpL and the IL were modeled with three and two symmetric fascicle pairs, respectively (Figure 1). The LTpTh was modeled with four symmetric fascicles with caudal insertions at the L3–L5 vertebrae and cranial insertions reconstructed to simulate the lines of action that virtually reach the T3–T6 levels of the thorax. We assumed a common rostral insertion of these cranial ends at the dorsal part of the third rib, represented as an enlarged transverse process of the third thoracic vertebra and modeled as a rigid rod. In simulated standing, this thoracic insertion was assumed to be cranio-caudally aligned with the uppermost vertebral level of the model, i.e., L3. A common musculotendon rest length was assumed for all thoracic elements based on the lumbar musculoskeletal RB model implemented by Christophy et al. (2012).

Bottom Line: Calculations led to intradiscal pressure values within ranges of values measured in vivo.Our simulations pointed out a likely existence of a functional balance between stretch-induced muscle activation and IVD multiphysics toward improved mechanical stability of the lumbar spine understanding.This balance suggests that proper night rest contributes to mechanically strengthen the spine during day activity.

View Article: PubMed Central - PubMed

Affiliation: Institute for Bioengineering of Catalonia , Barcelona , Spain ; Department of Information and Communication Technologies, Universitat Pompeu Fabra , Barcelona , Spain.

ABSTRACT
During daily activities, complex biomechanical interactions influence the biophysical regulation of intervertebral disks (IVDs), and transfers of mechanical loads are largely controlled by the stabilizing action of spine muscles. Muscle and other internal forces cannot be easily measured directly in the lumbar spine. Hence, biomechanical models are important tools for the evaluation of the loads in those tissues involved in low-back disorders. Muscle force estimations in most musculoskeletal models mainly rely, however, on inverse calculations and static optimizations that limit the predictive power of the numerical calculations. In order to contribute to the development of predictive systems, we coupled a predictive muscle model with the passive resistance of the spine tissues, in a L3-S1 musculoskeletal finite element model with osmo-poromechanical IVD descriptions. The model included 46 fascicles of the major back muscles that act on the lower spine. The muscle model interacted with activity-related loads imposed to the osteoligamentous structure, as standing position and night rest were simulated through distributed upper body mass and free IVD swelling, respectively. Calculations led to intradiscal pressure values within ranges of values measured in vivo. Disk swelling led to muscle activation and muscle force distributions that seemed particularly appropriate to counterbalance the anterior body mass effect in standing. Our simulations pointed out a likely existence of a functional balance between stretch-induced muscle activation and IVD multiphysics toward improved mechanical stability of the lumbar spine understanding. This balance suggests that proper night rest contributes to mechanically strengthen the spine during day activity.

No MeSH data available.


Related in: MedlinePlus