Viscoelastic stresses on anisotropic annulus fibrosus of lumbar disk under compression, rotation and flexion in manual treatment

Hans Chaudhry, Zhiming Ji, Nigel Shenoy, Thomas Findley

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Background: Twisting (spinal rotation) and bending (flexion) are commonly reported as triggers for low back pain. This paper addresses whether the twisting stress on the annulus fibrosus of the lumbar disk is greater or less than the bending stress for the same angle of twist or bending. Methods: Stress-strain relation for transversely isotropic material is applied to the transversely isotropic annulus fibrosus of the lumbar disk to analyze the viscoelastic stresses produced due to 6% compression, 10° twist and 10° bending. Findings: The bending stress is 450 times greater than the twisting stress for the same angle of twist or bending of the annulus fibrosus. The twisting and bending moments increase two-fold in quick maneuvers lasting 0.1 s (as in high velocity manipulations), compared to slow maneuvers lasting 60 s. Interpretation: From biomechanical perspective, in situations where both flexion and spinal rotation occur, the stress on the intervertebral disk is markedly higher with flexion compared to rotation. In patients with low back pain that has a disk mediated (discogenic) component, manipulation and mobilization therapies should avoid flexion to minimize stress on the disks. This is particularly relevant for high velocity manipulations where the stress on the disk is doubled for both flexion and rotation. The results in this paper can help guide manual therapists to adjust their treatments to minimize stress on the intervertebral disk.

Original languageEnglish (US)
Pages (from-to)182-191
Number of pages10
JournalJournal of Bodywork and Movement Therapies
Volume13
Issue number2
DOIs
StatePublished - Apr 2009

All Science Journal Classification (ASJC) codes

  • Complementary and Manual Therapy
  • Physical Therapy, Sports Therapy and Rehabilitation
  • Rehabilitation
  • Complementary and alternative medicine

Keywords

  • Annulus fibrosus
  • Bending
  • Compression
  • Flexion
  • Lumbar disk
  • Rotation
  • Twist
  • Viscoelastic stress

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