title: Effect of disc degeneration on lumbar segmental mobility analyzed by kinetic magnetic resonance imaging.
abstract: METHODS
  Retrospective radiographical study.
  
  
  OBJECTIVE
  To define the relationship between the grade of disc degeneration and the motion of the lumbar spine by using kinetic magnetic resonance imaging.
  
  
  BACKGROUND
  Disc degeneration is common after middle age. Lumbar instability has generally been recognized as a potential risk factor of low back pain. However, correlations between the grade of disc degeneration and the motion of the lumbar spine need more investigation.
  
  
  METHODS
  Kinetic magnetic resonance imaging was performed in 162 patients with symptomatic low back pain without prior history of surgery. The lumbar intervertebral discs were graded by spine surgeons according to the degenerative grading system (grades I-V). Translational motion and angular variation were measured at each segment from L1-L2 through L5-S1. The relationship between the degree of lumbar disc degeneration and extent of lumbar spine mobility was analyzed.
  
  
  RESULTS
  The translational motion in discs with grade I through IV increased gradually, but decreased with grade V. Compared with other less degenerative grades, grade V discs had significantly decreased total intervertebral translational motion (P < 0.05). The angular variation in discs with grade I through IV was fairly constant, but decreased with grade V. Compared with other degenerative grades (I-IV), grade V discs had significantly decreased total intervertebral translational motion (P < 0.05). For less degenerative grades I and II discs, the L2-L3 and L3-L4 segmental units contributed the majority of total angular mobility of the spine. However, for the severely degenerated segments, grade V discs, the contributions of the L2-L3 and L3-L4 significantly decreased (P < 0.01).
  
  
  CONCLUSIONS
  As disc degeneration developed from the normal to an increasingly severe stage, the motion of lumbar spine progressed from the normal stage to an unstable phase with higher mobility and finally to an ankylosed stage where stability was increased.
  
  
  METHODS
  3.
authors.affiliation: *Department of Orthopaedic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China †Department of Orthopaedic Surgery, University of California at Los Angeles (UCLA), Los Angeles, CA; and ‡Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Lao
authors.forename: Michael D
authors.initials: MD
authors.lastname: Daubs
authors.forename: Trevor P
authors.initials: TP
authors.lastname: Scott
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Lord
authors.forename: Jeremiah R
authors.initials: JR
authors.lastname: Cohen
authors.forename: Ruofeng
authors.initials: R
authors.lastname: Yin
authors.forename: Guibin
authors.initials: G
authors.lastname: Zhong
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D007593:Joint Instability / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D055815:Young Adult