Paraspinal muscle morphology, composition and asymmetries: determinants and relation to low back pain and pathology.

• Author / Creator

  Fortin, Maryse

• Background
  The lumbar paraspinal muscles are critical to provide spine stability, maintain proper posture and assist trunk movement. Although considerable attention has been focused on the association between variations in paraspinal muscle morphology and low back pain (LBP), their role in the development and progression of LBP remains unclear.

  Purpose
  The purpose of this doctoral work was to identify potential determinants of paraspinal muscle asymmetry, characterize the natural progression of age-related changes in paraspinal muscle over a 15-year period and examine their association with LBP problems, and determine whether paraspinal muscle size, composition and asymmetry are risk indicators for the development of LBP.

  Materials and Methods
  Subjects were selected from the pre-existing database of the Twin Spine Study. Data were collected through a structured interview, physical examination and magnetic resonance imaging (MRI). Measurement of the multifidus and erector spinae muscle cross-sectional area (CSA), functional CSA (FCSA) (e.g. fat-free mass) and degree of asymmetry in size and composition was obtained from T2-weighted axial images for 202 men at baseline and 99 men at 15-year follow-up. A novel and highly reliable thresholding technique, allowing for the separation of muscle and fat tissue, was developed to perform quantitative measurements of paraspinal muscle composition.

  Results and Conclusions
  Of the factors investigated, the few that were significantly associated with paraspinal muscle asymmetry in cross-sectional analyses included handedness, disc height narrowing, the amount of physical activity performed at work and leisure and familial aggregation. Yet, with the exception of handedness and familial aggregation, the associations were generally inconsistent across muscles and spinal levels and explained little of the variance in paraspinal muscle asymmetry. Over the 15-year follow-up period, the multifidus and erector spinae showed similar morphological changes including a decrease in size and an increase in fatty infiltration and asymmetry. However, no significant correlation was found between the long-term paraspinal muscle changes and LBP history. Moreover, multifidus and erector spinae muscle size, composition and degree of asymmetry do not appear to be major risk factors for the short-term (1-year) or long-term (15-year) development or prognosis of LBP, including sciatica.

• Subjects / Keywords

  • Erector spinae
  • Muscle morphology
  • Muscle composition
  • Magnetic resonance imaging
  • Low back pain
  • Paraspinal muscle
  • Fatty infiltration
  • Multifidus

• Graduation date

  Fall 2013

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3WM14499

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.