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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) Definition of the eccentric gravity load path passing through the segmental COM, (B) VC and COM locations at the L3–S1 FE model.
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Figure 2: (A) Definition of the eccentric gravity load path passing through the segmental COM, (B) VC and COM locations at the L3–S1 FE model.

Mentions: In order to simulate the standing position, we took into account the heterogeneous distribution of body volumes and densities along the trunk (Pearsall et al., 1996; Vette et al., 2011). We calculated the magnitude and point of application of an equivalent gravity load per simulated level, i.e., we translated the body mass distributions into punctual static loads, in function of the contribution expected from the rest of the upper body. In order to place the vertical loads, we defined an eccentric path that passed through the different segmental centers of mass (COM), anterior to the vertebral center (VC), and calculated the posteroanterior distance between VC and COM, Ri, per level (Figure 2). Calculations were applied to simulate a body weight of 70.8 kg of a normal subject.


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) Definition of the eccentric gravity load path passing through the segmental COM, (B) VC and COM locations at the L3–S1 FE model.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 2: (A) Definition of the eccentric gravity load path passing through the segmental COM, (B) VC and COM locations at the L3–S1 FE model.
Mentions: In order to simulate the standing position, we took into account the heterogeneous distribution of body volumes and densities along the trunk (Pearsall et al., 1996; Vette et al., 2011). We calculated the magnitude and point of application of an equivalent gravity load per simulated level, i.e., we translated the body mass distributions into punctual static loads, in function of the contribution expected from the rest of the upper body. In order to place the vertical loads, we defined an eccentric path that passed through the different segmental centers of mass (COM), anterior to the vertebral center (VC), and calculated the posteroanterior distance between VC and COM, Ri, per level (Figure 2). Calculations were applied to simulate a body weight of 70.8 kg of a normal subject.

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