title: Comparative study of radiographic disc height changes using two different interbody devices for transforaminal lumbar interbody fusion: open box vs. fenestrated tube interbody cage.
abstract: METHODS
  Retrospective comparative study of the postoperative subsidence of two interbody devices following posterior or transforaminal lumbar interbody fusion (PLIF/TLIF) for degenerative spondylolisthesis of the lumbar spine.
  
  
  OBJECTIVE
  To assess certain radiograph characteristics of PLIF/TLIF using two interbody fusion devices at L4-L5.
  
  
  BACKGROUND
  PLIF can achieve spinal stabilization with vertebral body support and direct neural decompression. Although various interbody devices have been used in PLIF procedures, no radiographic studies have compared the load-bearing capabilities of open box and fenestrated tube interbody cages.
  
  
  METHODS
  Seventy-five patients who underwent one-level PLIF in the L4-L5 [corrected] segment for degenerative spondylolisthesis were retrospectively reviewed with a minimum 2-year follow-up. Fenestrated tube (Group FT: n = 30 [corrected]) or open box (Group OB: n = 45 [corrected]) cages were used for the PLIF procedure. The following radiographic parameters were evaluated to compare the load-bearing capabilities: disc space height (DH); percent increase and decrease of disc height (% IDH and % DDH, respectively); and percent coverage of the cage on the endplate (% CC).
  
  
  RESULTS
  There were no significant differences in the baseline data, including age, segmental instability and osteoporotic status, between the two groups. Anterior %IDH and % CC were significantly higher in Group OB than in Group FT (% IDH: 69.4% vs. 57.3%; % OC: 24.5% vs. 12.9%), and anterior and posterior % DDH were significantly higher in Group FT than in Group OB (anterior: -2.9% vs. -.1%; posterior: -6.6% vs. -.3%). Although the restored DH gradually reduced over time in both groups, significant reduction to the preoperative level only occurred in Group FT.
  
  
  CONCLUSIONS
  The load-bearing capabilities of the open box cage are superior to those of the fenestrated tube cage. Since there were no significant differences between the baseline status of the two groups, the larger cross-sectional area and stable framework design of the open box cage appears to bring about a greater load-bearing capability. Therefore, the open box cage seems to be biomechanically more advantageous as an interbody device for PLIF than the fenestrated tube cage.
authors.affiliation: Center for Spinal Disorder and Injury, Bibai Rosai Hospital, Hokkaido, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Matsumura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Taneichi
authors.forename: Kota
authors.initials: K
authors.lastname: Suda
authors.forename: Tomomichi
authors.initials: T
authors.lastname: Kajino
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Moridaira
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kaneda
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D004867:Equipment Design; D005260:Female; D006801:Humans; D016268:Internal Fixators / Q000592:standards*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D013123:Spinal Fusion; D013168:Spondylolisthesis / Q000000981:diagnostic imaging* / Q000601:surgery*; D016474:Weight-Bearing