title: Flexion-extension rhythm in the lumbosacral spine.
abstract: OBJECTIVE
  This study was conducted to depict the qualitative and quantitative changes of intervertebral rotation and translation from L1-L2 to L5-S1 during flexion, standing, and extension using dynamic lumbosacral radiographs.
  
  
  METHODS
  A radiopaque ruler was placed on the back of each subject for the normalization of translational value. Eighty-nine volunteers were examined.
  
  
  RESULTS
  From extension to flexion, all of the intervertebral rotations approached 0 degree from the lordotic position; the translations changed from slightly retro-listhetic to zero displacement. Using L3-L4 as a baseline for calculating the intervertebral differences in flexion, all of the rotational differences were less than 1.5 degrees, except at L5-S1, which remained 5 degrees. The mean translational difference was less than 0.6 mm, except at L5-S1, where it remained 1.5 mm.
  
  
  CONCLUSIONS
  The amount of total flexibility was level-dependent and its frequency distribution is important. Qualitative rhythmic changes from extension to flexion and quantitative values of intervertebral difference in flexion help define the normal flexibility more accurately.
authors: Department of Orthopedics, National Cheng-Kung University Medical College, Tainan, Taiwan.
authors: R M
authors: RM
authors: Lin
authors: C Y
authors: CY
authors: Yu
authors: Z J
authors: ZJ
authors: Chang
authors: C C
authors: CC
authors: Lee
authors: F C
authors: FC
authors: Su
mesh_terms: D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology*; D008161:Lumbosacral Region; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology; D011187:Posture / Q000502:physiology; D011446:Prospective Studies; D011859:Radiography; D012399:Rotation; D012447:Sacrum / Q000000981:diagnostic imaging / Q000502:physiology*