A biomechanical model for estimating loads on thoracic and lumbar vertebrae

Sravisht Iyer, Blaine A Christiansen, Benjamin J. Roberts, Michael J. Valentine, Rajaram K. Manoharan, Mary L. Bouxsein

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

Background: Biomechanical models are commonly used to estimate loads on the spine. Current models have focused on understanding the etiology of low back pain and have not included thoracic vertebral levels. Using experimental data on the stiffness of the thoracic spine, ribcage, and sternum, we developed a new quasi-static stiffness-based biomechanical model to calculate loads on the thoracic and lumbar spine during bending or lifting tasks. Methods: To assess the sensitivity of the model to our key assumptions, we determined the effect of varying ribcage and sternal stiffness, maximum muscle stress, and objective function on predicted spinal loads. We compared estimates of spinal loading obtained with our model to previously reported in vivo intradiscal pressures and muscle activation patterns. Findings: Inclusion of the ribs and sternum caused an average decrease in vertebral compressive force of 33% for forward flexion and 18% in a lateral moment task. The impact of maximum muscle stress on vertebral force was limited to a narrow range of values. Compressive forces predicted by our model were strongly correlated to in vivo intradiscal pressure measurements in the thoracic (r = 0.95) and lumbar (r = 1) spine. Predicted trunk muscle activity was also strongly correlated (r = 0.95) with previously published EMG data from the lumbar spine. Interpretation: The consistency and accuracy of the model predictions appear to be sufficient to justify the use of this model for investigating the relationships between applied loads and injury to the thoracic spine during quasi-static loading activities.

Original languageEnglish (US)
Pages (from-to)853-858
Number of pages6
JournalClinical Biomechanics
Volume25
Issue number9
DOIs
StatePublished - Nov 2010
Externally publishedYes

Fingerprint

Thoracic Vertebrae
Lumbar Vertebrae
Spine
Thorax
Muscles
Sternum
Pressure
Thoracic Injuries
Ribs
Low Back Pain

Keywords

  • Back injury
  • Biomechanical model
  • Muscle activation
  • Spine

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Biophysics

Cite this

A biomechanical model for estimating loads on thoracic and lumbar vertebrae. / Iyer, Sravisht; Christiansen, Blaine A; Roberts, Benjamin J.; Valentine, Michael J.; Manoharan, Rajaram K.; Bouxsein, Mary L.

In: Clinical Biomechanics, Vol. 25, No. 9, 11.2010, p. 853-858.

Research output: Contribution to journalArticle

Iyer, Sravisht ; Christiansen, Blaine A ; Roberts, Benjamin J. ; Valentine, Michael J. ; Manoharan, Rajaram K. ; Bouxsein, Mary L. / A biomechanical model for estimating loads on thoracic and lumbar vertebrae. In: Clinical Biomechanics. 2010 ; Vol. 25, No. 9. pp. 853-858.
@article{e9394bdba7f6485e9758f4c4413d164d,
title = "A biomechanical model for estimating loads on thoracic and lumbar vertebrae",
abstract = "Background: Biomechanical models are commonly used to estimate loads on the spine. Current models have focused on understanding the etiology of low back pain and have not included thoracic vertebral levels. Using experimental data on the stiffness of the thoracic spine, ribcage, and sternum, we developed a new quasi-static stiffness-based biomechanical model to calculate loads on the thoracic and lumbar spine during bending or lifting tasks. Methods: To assess the sensitivity of the model to our key assumptions, we determined the effect of varying ribcage and sternal stiffness, maximum muscle stress, and objective function on predicted spinal loads. We compared estimates of spinal loading obtained with our model to previously reported in vivo intradiscal pressures and muscle activation patterns. Findings: Inclusion of the ribs and sternum caused an average decrease in vertebral compressive force of 33{\%} for forward flexion and 18{\%} in a lateral moment task. The impact of maximum muscle stress on vertebral force was limited to a narrow range of values. Compressive forces predicted by our model were strongly correlated to in vivo intradiscal pressure measurements in the thoracic (r = 0.95) and lumbar (r = 1) spine. Predicted trunk muscle activity was also strongly correlated (r = 0.95) with previously published EMG data from the lumbar spine. Interpretation: The consistency and accuracy of the model predictions appear to be sufficient to justify the use of this model for investigating the relationships between applied loads and injury to the thoracic spine during quasi-static loading activities.",
keywords = "Back injury, Biomechanical model, Muscle activation, Spine",
author = "Sravisht Iyer and Christiansen, {Blaine A} and Roberts, {Benjamin J.} and Valentine, {Michael J.} and Manoharan, {Rajaram K.} and Bouxsein, {Mary L.}",
year = "2010",
month = "11",
doi = "10.1016/j.clinbiomech.2010.06.010",
language = "English (US)",
volume = "25",
pages = "853--858",
journal = "Clinical Biomechanics",
issn = "0268-0033",
publisher = "Elsevier Limited",
number = "9",

}

TY - JOUR

T1 - A biomechanical model for estimating loads on thoracic and lumbar vertebrae

AU - Iyer, Sravisht

AU - Christiansen, Blaine A

AU - Roberts, Benjamin J.

AU - Valentine, Michael J.

AU - Manoharan, Rajaram K.

AU - Bouxsein, Mary L.

PY - 2010/11

Y1 - 2010/11

N2 - Background: Biomechanical models are commonly used to estimate loads on the spine. Current models have focused on understanding the etiology of low back pain and have not included thoracic vertebral levels. Using experimental data on the stiffness of the thoracic spine, ribcage, and sternum, we developed a new quasi-static stiffness-based biomechanical model to calculate loads on the thoracic and lumbar spine during bending or lifting tasks. Methods: To assess the sensitivity of the model to our key assumptions, we determined the effect of varying ribcage and sternal stiffness, maximum muscle stress, and objective function on predicted spinal loads. We compared estimates of spinal loading obtained with our model to previously reported in vivo intradiscal pressures and muscle activation patterns. Findings: Inclusion of the ribs and sternum caused an average decrease in vertebral compressive force of 33% for forward flexion and 18% in a lateral moment task. The impact of maximum muscle stress on vertebral force was limited to a narrow range of values. Compressive forces predicted by our model were strongly correlated to in vivo intradiscal pressure measurements in the thoracic (r = 0.95) and lumbar (r = 1) spine. Predicted trunk muscle activity was also strongly correlated (r = 0.95) with previously published EMG data from the lumbar spine. Interpretation: The consistency and accuracy of the model predictions appear to be sufficient to justify the use of this model for investigating the relationships between applied loads and injury to the thoracic spine during quasi-static loading activities.

AB - Background: Biomechanical models are commonly used to estimate loads on the spine. Current models have focused on understanding the etiology of low back pain and have not included thoracic vertebral levels. Using experimental data on the stiffness of the thoracic spine, ribcage, and sternum, we developed a new quasi-static stiffness-based biomechanical model to calculate loads on the thoracic and lumbar spine during bending or lifting tasks. Methods: To assess the sensitivity of the model to our key assumptions, we determined the effect of varying ribcage and sternal stiffness, maximum muscle stress, and objective function on predicted spinal loads. We compared estimates of spinal loading obtained with our model to previously reported in vivo intradiscal pressures and muscle activation patterns. Findings: Inclusion of the ribs and sternum caused an average decrease in vertebral compressive force of 33% for forward flexion and 18% in a lateral moment task. The impact of maximum muscle stress on vertebral force was limited to a narrow range of values. Compressive forces predicted by our model were strongly correlated to in vivo intradiscal pressure measurements in the thoracic (r = 0.95) and lumbar (r = 1) spine. Predicted trunk muscle activity was also strongly correlated (r = 0.95) with previously published EMG data from the lumbar spine. Interpretation: The consistency and accuracy of the model predictions appear to be sufficient to justify the use of this model for investigating the relationships between applied loads and injury to the thoracic spine during quasi-static loading activities.

KW - Back injury

KW - Biomechanical model

KW - Muscle activation

KW - Spine

UR - http://www.scopus.com/inward/record.url?scp=77957334885&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77957334885&partnerID=8YFLogxK

U2 - 10.1016/j.clinbiomech.2010.06.010

DO - 10.1016/j.clinbiomech.2010.06.010

M3 - Article

VL - 25

SP - 853

EP - 858

JO - Clinical Biomechanics

JF - Clinical Biomechanics

SN - 0268-0033

IS - 9

ER -