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BioMed Research International
Volume 2018, Article ID 4517471, 6 pages
https://doi.org/10.1155/2018/4517471
Research Article

The Effect of Muscle Direction on the Predictions of Finite Element Model of Human Lumbar Spine

1Spine Division of Orthopaedic Department, Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Shanghai 200065, China
2School of Electronics and Information Engineering, Tongji University, Shanghai 201804, China

Correspondence should be addressed to Zhi-li Zeng; moc.anis@667599lzz and Li-ming Cheng; nc.ude.ijgnot@gnehcgnimil

Received 7 October 2017; Revised 23 November 2017; Accepted 3 December 2017; Published 3 January 2018

Academic Editor: Liping Wang

Copyright © 2018 Rui Zhu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The normal physiological loads from muscles experienced by the spine are largely unknown due to a lack of data. The aim of this study is to investigate the effects of varying muscle directions on the outcomes predicted from finite element models of human lumbar spine. A nonlinear finite element model of L3–L5 was employed. The force of the erector spinae muscle, the force of the rectus abdominis muscle, follower loads, and upper body weight were applied. The model was fixed in a neural standing position and the direction of the force of the erector spinae muscle and rectus abdominis muscle was varied in three directions. The intradiscal pressure, reaction moments, and intervertebral rotations were calculated. The intradiscal pressure of L4-L5 was 0.56–0.57 MPa, which agrees with the in vivo pressure of 0.5 MPa from the literatures. The models with the erector spinae muscle loaded in anterior-oblique direction showed the smallest reaction moments (less than 0.6 Nm) and intervertebral rotations of L3-L4 and L4-L5 (less than 0.2 degrees). In comparison with loading in the vertical direction and posterior-oblique direction, the erector spinae muscle loaded in the anterior-oblique direction required lower external force or moment to keep the lumbar spine in the neutral position.