title: Volumetric change in interbody bone graft after posterior lumbar interbody fusion (PLIF): a prospective study.
abstract: OBJECTIVE
  The purpose of this study is to quantify the change in the volume of the interbody bone graft after the PLIF and monitor the change over time for subsequent analysis.
  
  
  METHODS
  The 114 cases were selected as the subjects of this study. The observation period was for 5 years following the surgery. The volume of the bone graft in the interbody space was calculated by summing up the cross-sectional area of the bone graft on each axial image multiplied by the height (2 mm) (the volume of the two cages was excluded). The volume ratio (%) = (bone graft volume)/(total volume of the interbody space - cage volume) was used for the purpose of evaluation.
  
  
  RESULTS
  The volumetric change of the bone graft was 51 % (3 months), 53 % (6 months), 54 % (1 year), 55 % (2 years), 59 % (3 years), 62 % (4 years), and 72 % (5 years), indicating a continued increase up to the 5-year mark. In particular, a significant increase was observed from the second year as compared with the previous years' result. Additionally, the volumetric increase from the second year to the fifth year was significantly higher than that before the second year.
  
  
  CONCLUSIONS
  The post-PLIF volumes of interbody bone grafts exhibited increases particularly from the second to fifth years after the procedure. Even the elderly and those with poor bone qualities can expect to have volumetric increases over time. Sufficient interbody space should be secured for accommodating bone grafts by intraoperative reduction, wherever possible.
authors.affiliation: Department of Orthopedic Surgery, Nagoya University School of Medicine, 65 Tsurumai Shyowa-ward, Nagoya, 466-8550, Aichi, Japan, z.ito@nifty.com.
authors.forename: Zenya
authors.initials: Z
authors.lastname: Ito
authors.forename: Shiro
authors.initials: S
authors.lastname: Imagama
authors.forename: Tokumi
authors.initials: T
authors.lastname: Kanemura
authors.forename: Kotaro
authors.initials: K
authors.lastname: Satake
authors.forename: Kei
authors.initials: K
authors.lastname: Ando
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Shinjo
authors.forename: Hideki
authors.initials: H
authors.lastname: Yagi
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Hida
authors.forename: Kenyu
authors.initials: K
authors.lastname: Ito
authors.forename: Yoshimoto
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: Mikito
authors.initials: M
authors.lastname: Tsushima
authors.forename: Akiyuki
authors.initials: A
authors.lastname: Matsumoto
authors.forename: Hany
authors.initials: H
authors.lastname: El Zahlawy
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Matsuyama
authors.forename: Naoki
authors.initials: N
authors.lastname: Ishiguro
mesh_terms: D000368:Aged; D016723:Bone Remodeling; D016025:Bone Transplantation / Q000009:adverse effects / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000601:surgery; D007405:Intervertebral Disc Displacement / Q000000981:diagnostic imaging / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008161:Lumbosacral Region / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000517:prevention & control; D011184:Postoperative Period; D011446:Prospective Studies; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods*; D013130:Spinal Stenosis / Q000000981:diagnostic imaging / Q000601:surgery; D013168:Spondylolisthesis / Q000000981:diagnostic imaging / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome