title: Sagittal plane lumbar intervertebral motion during seated flexion-extension radiographs of 658 asymptomatic nondegenerated levels.
abstract: OBJECTIVE
  Evaluation of lumbar stability is fundamentally dependent on a clear understanding of normal lumbar motion. There are inconsistencies in reported lumbar motion across previously published studies, and it is unclear which provide the most reliable reference data. New technology now allows valid and reliable determination of normal lumbar intervertebral motion (IVM). The object of this study was to provide normative reference data for lumbar IVM and center of rotation (COR) using validated computer-assisted measurement tools.
  
  
  METHODS
  Sitting flexion-extension radiographs were obtained in 162 asymptomatic volunteers and then analyzed using a previously validated and widely used computerized image analysis method. Each lumbar level was subsequently classified as "degenerated" or "nondegenerated" using the Kellgren-Lawrence classification. Of the 803 levels analyzed, 658 were nondegenerated (Kellgren-Lawrence grade < 2). At each level of the lumbar spine, the magnitude of intervertebral rotation and translation, the ratio of translation per degree of rotation (TPDR), and the position of the COR were calculated in the nondegenerative cohort. Translations were calculated in millimeters and percentage endplate width.
  
  
  RESULTS
  All parameters were significantly dependent on the intervertebral level. The upper limit of the 95% CIs for anteroposterior intervertebral translation in this asymptomatic cohort ranged from 2.1 mm (6.2% endplate width) to 4.6 mm (13.3% endplate width). Intervertebral rotation upper limits ranged from 16.3° to 23.5°. The upper limits for TPDR ranged from 0.49% to 0.82% endplate width/degree. The COR coordinates were clustered in level-dependent patterns.
  
  
  CONCLUSIONS
  New normal values for IVM, COR, and the ratio of TPDR in asymptomatic nondegenerative lumbar levels are proposed, providing a reference for future interpretation of sagittal plane motion in the lumbar spine.
authors: Department of Neurosurgery, Houston Methodist Neurological Institute, Methodist Hospital;
authors: Blake N
authors: BN
authors: Staub
authors: Department of Neurosurgery, Houston Methodist Neurological Institute, Methodist Hospital;
authors: Paul J
authors: PJ
authors: Holman
authors: Department of Orthopedic Surgery, Baylor College of Medicine; and.
authors: Charles A
authors: CA
authors: Reitman
authors: Medical Metrics Inc., Houston, Texas.
authors: John
authors: J
authors: Hipp
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007403:Intervertebral Disc / Q000000981:diagnostic imaging* / Q000502:physiology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D012016:Reference Values; D055815:Young Adult
keywords: COR = center of rotation; IVM = intervertebral motion; QMA = Quantitative Motion Analysis; TPDR = translation per degree of rotation; center of rotation; computer-assisted measurement; flexion-extension; instantaneous axis of rotation; intervertebral motion; lumbar; translation per degree of rotation