title: Use of ultrasonography to evaluate thickness of the erector spinae muscle in maximum flexion and extension of the lumbar spine.
abstract: METHODS
  An observational study of the changes in thickness of the erector spinae (ES) muscle in three different trunk postures.
  
  
  OBJECTIVE
  To use ultrasonography to evaluate the thickness of the ES muscle in three different trunk postures.
  
  
  BACKGROUND
  Although there has been extensive study of the morphology of the ES muscle during prolonged trunk flexion, we have little information about the changes in thickness of these muscles in various postures of the lumbar spine. Ultrasonography has never been used to measure the thickness of ES muscle.
  
  
  METHODS
  We studied 30 volunteers with no history of lower back problems. We used ultrasonography to measure the thickness of the ES muscle at each lumbar level (L1, L2, L3, L4, and L5) in maximum flexion, neutral posture, and maximum extension. We tested the reliability of this method by evaluating intraobserver and interobserver differences in 13 subjects.
  
  
  RESULTS
  The high correlation between intraobserver and interobserver measurements in the 13 subjects demonstrated that the method provides sufficient reproducibility. When the trunk was flexed maximally, the thickness of the ES muscle was significantly decreased at each lumbar vertebral level. When the trunk was extended maximally, the thickness of the ES muscle was significantly increased at each lumbar vertebral level.
  
  
  CONCLUSIONS
  The thickness of the ES muscle decreases as the lumbar spine flexes and increases as it extends. We used ultrasonography successfully for quantitative evaluation of changes in thickness of the ES muscle with postural changes in the lumbar spine.
authors.affiliation: Watanabe Orthopaedic Clinic, Gifu University, School of Medicine, Gifu, Japan.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Watanabe
authors.forename: Kei
authors.initials: K
authors.lastname: Miyamoto
authors.forename: Takahiro
authors.initials: T
authors.lastname: Masuda
authors.forename: Katsuji
authors.initials: K
authors.lastname: Shimizu
mesh_terms: D000328:Adult; D000886:Anthropometry / Q000379:methods*; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae; D008161:Lumbosacral Region / Q000000981:diagnostic imaging*; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D015588:Observer Variation; D011187:Posture; D016059:Range of Motion, Articular; D012016:Reference Values; D015203:Reproducibility of Results; D014463:Ultrasonography