title: A biomechanical cadaveric study of a modified U-shaped interspinous distraction device.
abstract: METHODS
  An experimental study.
  
  
  OBJECTIVE
  To analyze the effects of a modified U-shape interspinous distraction device (IDD) on the stability of a destabilized lumbar spine model.
  
  
  BACKGROUND
  The use of IDD for treatment of lumbar spine pathology remains a subject of debate. A modified design of an IDD consisted of a titanium (Ti) U-shape dynamic stabilizer and a Ti tensioning wire loop was biomechanically tested.
  
  
  METHODS
  Six sets of cadaveric lumbar vertebrae levels 1-5 (L1-L5) were subjected to loads in flexion, extension, and lateral bending in the 4 following sequences: intact specimen, unilateral facetectomy and discectomy at L3-L4, insertion of the modified U-shape IDD at L3-L4, and pedicle screw fixation at L3-L4. The range of motion (ROM) of L3-L4 following modified U-shape IDD insertion was compared with that of the intact specimen. The ROM of the adjacent vertebrae (L2-L3 and L4-L5) following modified U-shape IDD insertion was compared with that after pedicle screw fixation. Statistical analysis was performed using the Wilcoxon signed-rank test.
  
  
  RESULTS
  The modified U-shape IDD decreased the ROM of a destabilized L3-L4 in all testing load (P<0.05). The stability of L3-L4 following the modified U-shape IDD insertion was restored to that of the intact specimen (P>0.05). The ROM at adjacent vertebrae after the modified U-shape IDD placement was similar to the ROM obtained after pedicle screw fixation at L3-L4.
  
  
  CONCLUSIONS
  The modified version of a U-shape IDD is effective in stabilizing an unstable segment of the lumbar spine. The device does not create deleterious effects on the adjacent vertebrae.
authors: *Department of Orthopedics, Faculty of Medicine, Chulalongkorn University †King Chulalongkorn Memorial Hospital, Thai Red Cross Society ‡Department of Mechanical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand.
authors: Weerasak
authors: W
authors: Singhatanadgige
authors: Pairat
authors: P
authors: Tangpornprasert
authors: Yongsak
authors: Y
authors: Wangroongsub
authors: Pibul
authors: P
authors: Itiravivong
authors: Noppachart
authors: N
authors: Limpaphayom
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D001863:Bone Screws; D002102:Cadaver; D017586:Diskectomy / Q000295:instrumentation; D005260:Female; D006801:Humans; D016268:Internal Fixators; D055959:Intervertebral Disc Degeneration / Q000601:surgery*; D007593:Joint Instability / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000502:physiology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D014025:Titanium
chemical_list: D014025:Titanium