title: Morphology versus function: the relationship between lumbar multifidus intramuscular adipose tissue and muscle function among patients with low back pain.
abstract: OBJECTIVE
  To explore the bivariate and multivariate relations between fatty degeneration of the lumbar multifidus muscle (LMM) and LMM function among patients with low back pain (LBP).
  
  
  METHODS
  Cross-sectional clinical study.
  
  
  METHODS
  Hospital.
  
  
  METHODS
  Patients with LBP (N=70) referred for lumbar spine magnetic resonance imaging.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  LMM morphology and function were measured at the L4/L5 and L5/S1 spinal levels bilaterally. Quantitative measures of LMM intramuscular adipose tissue (IMAT) were derived from T1-weighted magnetic resonance images. Function was assessed with ultrasound imaging by measuring change in LMM thickness during a submaximal contraction task. The study participants self-reported their level of LBP-related disability (Modified Oswestry Index), pain intensity (numerical pain rating scale), and physical activity (International Physical Activity Questionnaire). Bivariate and multivariate relations between LMM morphology and function were explored with correlational and hierarchical linear regression analyses, respectively. Additionally, we explored for possible covariates with potential to modify the relation between LMM IMAT and function.
  
  
  RESULTS
  There were 70 participants (12 women) enrolled in the study (mean age, 45.4±11.9y). A high level of physical activity was reported by 45.5% of participates. Age, sex, and physical activity level demonstrated variable relations with LMM IMAT and LMM function. There were no significant bivariate or multivariate relations between LMM IMAT and LMM function.
  
  
  CONCLUSIONS
  We observed higher levels of physical activity and LMM function and less LMM IMAT than previous studies involving patients with LBP. There was no relation between LMM morphology and function in this cohort of patients with LBP. Issues specific to LMM measurement and recommendations for future research are discussed.
authors.affiliation: Rocky Mountain University of Health Professions, Provo, UT.
authors.forename: Edward C
authors.initials: EC
authors.lastname: Le Cara
authors.affiliation: Department of Physical Therapy, University of Utah, Salt Lake City, UT.
authors.forename: Robin L
authors.initials: RL
authors.lastname: Marcus
authors.affiliation: School of Psychology and Exercise Science, Murdoch University, Murdoch, WA, Australia.
authors.forename: Alasdair R
authors.initials: AR
authors.lastname: Dempsey
authors.affiliation: Department of Physical Medicine and Rehabilitation, Department of Veterans Affairs, Northern California Health Care System, Sacramento, CA; University of California Davis Medical Center, Sacramento, CA.
authors.forename: Martin D
authors.initials: MD
authors.lastname: Hoffman
authors.affiliation: School of Psychology and Exercise Science, Murdoch University, Murdoch, WA, Australia. Electronic address: J.Hebert@Murdoch.edu.au.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Hebert
mesh_terms: D000273:Adipose Tissue / Q000473:pathology*; D000328:Adult; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000473:pathology* / Q000503:physiopathology*; D008161:Lumbosacral Region; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D015999:Multivariate Analysis; D009119:Muscle Contraction; D010147:Pain Measurement; D064170:Paraspinal Muscles / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D057566:Self Report; D014463:Ultrasonography
keywords: Adipose tissue; Low back pain; Magnetic resonance imaging; Paraspinal muscles; Rehabilitation; Ultrasonography