A Musculoskeletal model for the lumbar spine

  • Miguel Christophy
  • Nur Adila Faruk Senan
  • Jeffrey C. Lotz
  • Oliver M. O’Reilly
Open Access
Original Paper


A new musculoskeletal model for the lumbar spine is described in this paper. This model features a rigid pelvis and sacrum, the five lumbar vertebrae, and a rigid torso consisting of a lumped thoracic spine and ribcage. The motion of the individual lumbar vertebrae was defined as a fraction of the net lumbar movement about the three rotational degrees of freedom: flexion–extension lateral bending, and axial rotation. Additionally, the eight main muscle groups of the lumbar spine were incorporated using 238 muscle fascicles with prescriptions for the parameters in the Hill-type muscle models obtained with the help of an extensive literature survey. The features of the model include the abilities to predict joint reactions, muscle forces, and muscle activation patterns. To illustrate the capabilities of the model and validate its physiological similarity, the model’s predictions for the moment arms of the muscles are shown for a range of flexion–extension motions of the lower back. The model uses the OpenSim platform and is freely available on to other spinal researchers interested in analyzing the kinematics of the spine. The model can also be integrated with existing OpenSim models to build more comprehensive models of the human body.


Spinal kinematics Musculoskeletal model Hill-type model Muscle architecture 



The authors thank Professor Scott Delp and the OpenSim team for their generous technical support with this software, acknowledge the inspiration provided by the cervical spine model in Vasavada et al. (1998), and express their appreciation to the reviewers for their helpful comments and suggestions. The work of the authors was partially supported by the National Science Foundation of the United States under Grant No. CMMI 0726675.

Open Access

This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.


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Copyright information

© The Author(s) 2011

Authors and Affiliations

  • Miguel Christophy
    • 1
  • Nur Adila Faruk Senan
    • 1
  • Jeffrey C. Lotz
    • 2
  • Oliver M. O’Reilly
    • 1
  1. 1.Department of Mechanical EngineeringUniversity of California at BerkeleyBerkeleyUSA
  2. 2.Department of Orthopaedic SurgeryUniversity of California at San FranciscoSan FranciscoUSA

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