title: In Vivo Characteristics of Nondegenerated Adjacent Segment Intervertebral Foramina in Patients With Degenerative Disc Disease During Flexion-Extension.
abstract: METHODS
  In vivo patient biomechanical study.
  
  
  OBJECTIVE
  To investigate the dimensions of lumbar intervertebral foramen (LIVF) of patients with degenerative disc disease (DDD) during a flexion-extension motion of the body.
  
  
  BACKGROUND
  LIVF narrowing may result in nerve root compression. The area changes of degenerated and adjacent nondegenerated LIVFs in DDD patients under physiologic loading conditions are unknown.
  
  
  METHODS
  Nine symptomatic low back pain patients with radiological evidence of L4-S1 DDD were recruited. Each subject was magnetic resonance imaging scanned for construction of three-dimensional lumbar vertebral models, and fluoroscopically imaged when the body extended from 45 flexion to full extension for reconstruction of LIVF dimensions. The data of the adjacent segment L3/4 and diseased segments L4/5 and L5/S1 were compared with a normal control group at 45 flexion, upright, and full extension of the body.
  
  
  RESULTS
  The mean LIVF areas of DDD segments were significantly smaller than those of the normal subjects in all positions (P <0.05). In upright position, the LIVF areas of the DDD patients were 32.8% and 33.6% smaller than the normal subjects for L4/5 and L5/S1, respectively. For the adjacent L3/4, the LIVF area of the DDD patients was 32.3% smaller than that of the normal controls (P <0.05). The total change of L3/4 LIVF area in DDD patients from flexion to extension was significantly smaller than that of the normal subjects, but the changes in L4/5 and L5/S1 LIVF areas were similar between the two groups (P >0.05).
  
  
  CONCLUSIONS
  Similar reductions of the LIVF dimensions were observed at the adjacent and the involved levels of the DDD patients, implying that biomechanical changes might have already occurred at the adjacent segment despite the lack of radiographic evidence of degeneration. Subsequent research should focus on the effects of surgical fusion on the biomechanical features of the adjacent segment.
  
  
  METHODS
  N/A.
authors.affiliation: Bioengineering Lab, Department of Orthopaedic Surgery, Massachusetts General Hospital/Harvard Medical School, Boston, MA.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Cha
authors.affiliation: Bioengineering Lab, Department of Orthopaedic Surgery, Massachusetts General Hospital/Harvard Medical School, Boston, MA.
authors.forename: Gregory
authors.initials: G
authors.lastname: Moore
authors.affiliation: Bioengineering Lab, Department of Orthopaedic Surgery, Massachusetts General Hospital/Harvard Medical School, Boston, MA.|Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.
authors.forename: Ming Han Lincoln
authors.initials: MHL
authors.lastname: Liow
authors.affiliation: Department of Orthopaedic Surgery, Second Xiangya Hospital and Central South University, Changsha, Hunan, China.
authors.forename: Weiye
authors.initials: W
authors.lastname: Zhong
authors.affiliation: Department of Orthopedics, The Second Hospital of Jilin University, Changchun, Jilin, China.
authors.forename: Minfei
authors.initials: M
authors.lastname: Wu
authors.affiliation: Bioengineering Lab, Department of Orthopaedic Surgery, Massachusetts General Hospital/Harvard Medical School, Boston, MA.
authors.forename: Shaobai
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Orthopaedic Surgery, Brigham and Women's Hospital/Harvard Medical School, Boston, MA.
authors.forename: James D
authors.initials: JD
authors.lastname: Kang
authors.affiliation: Department of Orthopedics - Arthritis and Joint Replacement, Stanford University, Redwood City, CA.
authors.forename: Kirkham B
authors.initials: KB
authors.lastname: Wood
authors.affiliation: Bioengineering Lab, Department of Orthopaedic Surgery, Massachusetts General Hospital/Harvard Medical School, Boston, MA.
authors.forename: Guoan
authors.initials: G
authors.lastname: Li
mesh_terms: D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000601:surgery*; D055959:Intervertebral Disc Degeneration / Q000473:pathology*; D017116:Low Back Pain / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008161:Lumbosacral Region / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology*; D012447:Sacrum / Q000601:surgery; D013123:Spinal Fusion / Q000379:methods