title: Reduced thoracolumbar fascia shear strain in human chronic low back pain.
abstract: BACKGROUND
  The role played by the thoracolumbar fascia in chronic low back pain (LBP) is poorly understood. The thoracolumbar fascia is composed of dense connective tissue layers separated by layers of loose connective tissue that normally allow the dense layers to glide past one another during trunk motion. The goal of this study was to quantify shear plane motion within the thoracolumbar fascia using ultrasound elasticity imaging in human subjects with and without chronic low back pain (LBP).
  
  
  METHODS
  We tested 121 human subjects, 50 without LBP and 71 with LBP of greater than 12 months duration. In each subject, an ultrasound cine-recording was acquired on the right and left sides of the back during passive trunk flexion using a motorized articulated table with the hinge point of the table at L4-5 and the ultrasound probe located longitudinally 2 cm lateral to the midline at the level of the L2-3 interspace. Tissue displacement within the thoracolumbar fascia was calculated using cross correlation techniques and shear strain was derived from this displacement data. Additional measures included standard range of motion and physical performance evaluations as well as ultrasound measurement of perimuscular connective tissue thickness and echogenicity.
  
  
  RESULTS
  Thoracolumbar fascia shear strain was reduced in the LBP group compared with the No-LBP group (56.4% ± 3.1% vs. 70.2% ± 3.6% respectively, p < .01). There was no evidence that this difference was sex-specific (group by sex interaction p = .09), although overall, males had significantly lower shear strain than females (p = .02). Significant correlations were found in male subjects between thoracolumbar fascia shear strain and the following variables: perimuscular connective tissue thickness (r = -0.45, p <.001), echogenicity (r = -0.28, p < .05), trunk flexion range of motion (r = 0.36, p < .01), trunk extension range of motion (r = 0.41, p < .01), repeated forward bend task duration (r = -0.54, p < .0001) and repeated sit-to-stand task duration (r = -0.45, p < .001).
  
  
  CONCLUSIONS
  Thoracolumbar fascia shear strain was ~20% lower in human subjects with chronic low back pain. This reduction of shear plane motion may be due to abnormal trunk movement patterns and/or intrinsic connective tissue pathology. There appears to be some sex-related differences in thoracolumbar fascia shear strain that may also play a role in altered connective tissue function.
authors.affiliation: Department of Neurology, University of Vermont, Burlington VT, USA. helene.langevin@uvm.edu
authors.forename: Helene M
authors.initials: HM
authors.lastname: Langevin
authors.forename: James R
authors.initials: JR
authors.lastname: Fox
authors.forename: Cathryn
authors.initials: C
authors.lastname: Koptiuch
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Badger
authors.forename: Ann C
authors.initials: AC
authors.lastname: Greenan-Naumann
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Bouffard
authors.forename: Elisa E
authors.initials: EE
authors.lastname: Konofagou
authors.forename: Wei-Ning
authors.initials: WN
authors.lastname: Lee
authors.forename: John J
authors.initials: JJ
authors.lastname: Triano
authors.forename: Sharon M
authors.initials: SM
authors.lastname: Henry
mesh_terms: D000328:Adult; D002908:Chronic Disease; D005205:Fascia / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D016059:Range of Motion, Articular; D033081:Shear Strength; D013180:Sprains and Strains / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D014463:Ultrasonography; D016474:Weight-Bearing