title: Segmental lumbar rotation in patients with discogenic low back pain during functional weight-bearing activities.
abstract: BACKGROUND
  Little information is available on vertebral motion in patients with discogenic low back pain under physiological conditions. We previously validated a combined dual fluoroscopic and magnetic resonance imaging system to investigate in vivo lumbar kinematics. The purpose of the present study was to characterize mechanical dysfunction among patients with confirmed discogenic low back pain, relative to asymptomatic controls without degenerative disc disease, by quantifying abnormal vertebral motion.
  
  
  METHODS
  Ten subjects were recruited for the present study. All patients had discogenic low back pain confirmed clinically and radiographically at L4-L5 and L5-S1. Motions were reproduced with use of the combined imaging technique during flexion-extension, left-to-right bending, and left-to-right twisting movements. From local coordinate systems at the end plates, relative motions of the cephalad vertebrae with respect to caudad vertebrae were calculated at each of the segments from L2 to S1. Range of motion of the primary rotations and coupled translations and rotations were determined.
  
  
  RESULTS
  During all three movements, the greatest range of motion was observed at L3-L4. L3-L4 had significantly greater motion than L2-L3 with left-right bending and left-right twisting movements (p < 0.05). The least motion occurred at L5-S1 for all movements; the motion at this level was significantly smaller than that at L3-L4 (p < 0.05). Range of motion during left-right bending and left-right twisting at L3-L4 was significantly larger in the degenerative disc disease group than in the normal group. The range of motion at L4-L5 was significantly larger in the degenerative group than in the normal group during flexion; however, the ranges of motion in both groups were similar during left-to-right bending and left-to-right twisting.
  
  
  CONCLUSIONS
  The greatest range of motion in patients with discogenic back pain was observed at L3-L4; this motion was greater than that in normal subjects, suggesting that superior adjacent levels developed segmental hypermobility prior to undergoing fusion. L5-S1 had the least motion, suggesting that segmental hypomobility ensues at this level in patients with discogenic low back pain.
authors.affiliation: Bioengineering Laboratory, Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, MA 02114, USA. panagmd@gmail.com
authors.forename: Peter G
authors.initials: PG
authors.lastname: Passias
authors.forename: Shaobai
authors.initials: S
authors.lastname: Wang
authors.forename: Michal
authors.initials: M
authors.lastname: Kozanek
authors.forename: Qun
authors.initials: Q
authors.lastname: Xia
authors.forename: Weishi
authors.initials: W
authors.lastname: Li
authors.forename: Brian
authors.initials: B
authors.lastname: Grottkau
authors.forename: Kirkham B
authors.initials: KB
authors.lastname: Wood
authors.forename: Guoan
authors.initials: G
authors.lastname: Li
mesh_terms: D001696:Biomechanical Phenomena; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D055959:Intervertebral Disc Degeneration / Q000503:physiopathology*; D017116:Low Back Pain / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012399:Rotation; D016474:Weight-Bearing