title: Morphologic Changes in Contralateral Lumbar Foramen in Unilateral Cantilever Transforaminal Lumbar Interbody Fusion Using Kidney-type Intervertebral Spacers.
abstract: METHODS
  A retrospective study of 58 patients undergoing cantilever transforaminal lumbar interbody fusion (c-TLIF).
  
  
  OBJECTIVE
  To evaluate morphologic changes in the intervertebral foramen (IVF) on the side contralateral to spacer insertion in patients undergoing c-TLIF using plain x-ray films and computed tomography scan.
  
  
  BACKGROUND
  The morphologic changes in the contralateral lumbar foramen in c-TLIF using unilateral insertion of spacers have not been well studied.
  
  
  METHODS
  Fifty-eight consecutive patients with lumbar dysplastic changes or degenerative disk diseases underwent c-TLIF using 96 kidney-type spacers with local bone grafts. Radiographic findings (sagittal disk angle), computed tomography scan findings (coronal disk angle, disk height, foraminal height (FH), foraminal width, and cross-sectional area of IVF in contralateral lumbar foramen) were compared between preoperative period and 6 months after surgery. The correlations between contralateral lumbar foraminal dimensions and disk height, sagittal disk angle, and coronal disk angle were analyzed.
  
  
  RESULTS
  After c-TLIF, sagittal angle, disk height, FH, foraminal width, and cross-sectional area of the IVF were significantly increased. Increase in posterior disk height showed a positive correlation with increases in FH, foraminal width, and cross-sectional area of IVF (r=0.235-0.511). However, the increase in sagittal disk angle showed a negative correlation with changes in foraminal width and cross-sectional area of IVF (r=-0.256 to -0.206).
  
  
  CONCLUSIONS
  Lumbar foraminal dimensions on the side contralateral to spacer insertion increased significantly after c-TLIF, suggesting that c-TLIF enables indirect decompression of the contralateral nerve root. Although increase in posterior disk height was shown to be an important factor to increase contralateral foraminal size, segmental lordosis was a risk factor for a decrease in contralateral foraminal size.
authors: *Department of Orthopaedic Surgery, Ibi Kousei Hospital Departments of †Orthopaedic Surgery ‡Reconstructive Surgery for Spine, Bone, and Joint, Gifu University Graduate School of Medicine, Gifu, Japan.
authors: Takahiro
authors: T
authors: Iwata
authors: Kei
authors: K
authors: Miyamoto
authors: Akira
authors: A
authors: Hioki
authors: Kazunari
authors: K
authors: Fushimi
authors: Takatoshi
authors: T
authors: Ohno
authors: Katsuji
authors: K
authors: Shimizu
mesh_terms: D000328:Adult; D000368:Aged; D019412:Anatomy, Cross-Sectional; D005260:Female; D006801:Humans; D016268:Internal Fixators; D007403:Intervertebral Disc / Q000000981:diagnostic imaging; D055959:Intervertebral Disc Degeneration / Q000000981:diagnostic imaging* / Q000601:surgery*; D008141:Lordosis / Q000000981:diagnostic imaging; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013123:Spinal Fusion / Q000295:instrumentation*; D013126:Spinal Nerve Roots / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed