title: The effect of spinal osteotomies on spinal cord tension and dural buckling: a cadaveric study.
abstract: OBJECTIVE
  The standard surgical release of a tethered cord may result in recurrent scar formation and occasionally be associated with retethering. The application of spinal shortening procedures to this challenging problem potentially can reduce tension on the retethered spinal cord while minimizing the difficulties inherent in traditional lumbosacral detethering revision. Although spinal shortening procedures have proven clinical benefit in patients with a recurrent tethered cord, it is unclear how much shortening is required to achieve adequate reduction in spinal cord tension or what impact these osteotomies have on dural buckling.
  
  
  METHODS
  The authors calculated mean values from 4 human cadavers to evaluate the effect of 3 different spinal shortening procedures--Smith-Petersen osteotomy (SPO), pedicle subtraction osteotomy (PSO), and vertebral column resection (VCR)--on spinal cord tension and dural buckling. Three cadavers were dedicated to the measurement of spinal cord tension, and 3 other cadavers were devoted to myelography to measure dural buckling parameters.
  
  
  RESULTS
  The SPO was associated with a maximal decrease in spinal cord tension of 16.1% from baseline and no dural buckling with any degree of closure. The PSO led to a mean maximal decrease in spinal cord tension of 63.1% from baseline at 12 mm of closure and demonstrated a direct linear relationship between dural buckling and increasing osteotomy closure. Finally, VCR closure correlated with a mean maximal decrease in spinal cord tension of 87.2% from baseline at 10 mm of closure and also showed a direct linear relationship between dural buckling and increases in osteotomy closure.
  
  
  CONCLUSIONS
  In this cadaveric experiment, the SPO did not lead to appreciable tension reduction, while a substantial response was seen with both the PSO and VCR. The rate of tension reduction may be steeper for the VCR than the PSO. Adequate tension relief while minimizing dural buckling may be optimal with 12-16 mm of posterior osteotomy closure based on this cadaveric experiment.
authors.affiliation: Department of Neurosurgery, Tufts Medical Center;|Department of Neurosurgery, Tufts University School of Medicine, Boston, Massachusetts; and.
authors.forename: Mina G
authors.initials: MG
authors.lastname: Safain
authors.affiliation: Department of Neurosurgery, Tufts Medical Center;|Department of Neurosurgery, Tufts University School of Medicine, Boston, Massachusetts; and.
authors.forename: Shane M
authors.initials: SM
authors.lastname: Burke
authors.affiliation: Department of Neurosurgery, Tufts Medical Center;|Department of Neurosurgery, Tufts University School of Medicine, Boston, Massachusetts; and.
authors.forename: Ron I
authors.initials: RI
authors.lastname: Riesenburger
authors.affiliation: University of Cyprus, Nicosia, Cyprus.
authors.forename: Vasilios
authors.initials: V
authors.lastname: Zerris
authors.affiliation: Department of Neurosurgery, Tufts Medical Center;|Department of Neurosurgery, Tufts University School of Medicine, Boston, Massachusetts; and.
authors.forename: Steven W
authors.initials: SW
authors.lastname: Hwang
mesh_terms: D001863:Bone Screws; D002102:Cadaver; D005471:Fluoroscopy; D006801:Humans; D009436:Neural Tube Defects / Q000601:surgery*; D019635:Neurosurgical Procedures / Q000379:methods*; D010027:Osteotomy / Q000379:methods; D012008:Recurrence
keywords: PSO = pedicle subtraction osteotomy; SPO = Smith-Petersen osteotomy; Smith-Petersen osteotomy; VCR = vertebral column resection; dural buckling; pedicle subtraction osteotomy; technique; tension; tethered cord syndrome; vertebral column resection