title: Unilateral and bilateral pedicle screw fixation in transforaminal lumbar interbody fusion: radiographic and clinical analysis.
abstract: BACKGROUND
  Transforaminal lumbar interbody fusion with bilateral segmental pedicle screw (PS) fixation is a widely used and well-recognized technique that provides fixation and load-bearing capacity, while restoring morphometric spine parameters and relieving symptoms in patients with degenerative disc disease. A supplemental interspinous process fixation plate (ISFP) as an adjunct to unilateral PS fixation allows for reduced invasiveness of this technique compared with bilateral PS placement. The biomechanical comparison results have been previously reported, but the significance of these findings has not been studied in clinical settings.
  
  
  METHODS
  A prospective cohort study with a supplemental retrospective chart review and radiographic analysis was performed. Patients were divided into 2 groups: bilateral PS fixation (n = 75) or unilateral PS fixation + ISFP (n = 96). Lateral lumbar standing radiographs were obtained for preoperative and postoperative foraminal height (FH), disc height, segmental sagittal alignment, and lumbar sagittal alignment measurements. Standardized questionnaires were used to compare postoperative clinical outcomes.
  
  
  RESULTS
  The estimated blood loss, duration of procedure, and length of hospital stay were significantly lower for 1-level and 2-level procedures in the unilateral PS + ISFP group. A statistically significant mean disc height increase was observed in both groups. Regardless of the disc height increase, a statistically significant FH loss was detected in the bilateral PS group (from 17.1 mm to 16.3 mm; 4.7% loss; P = 0.04) compared with FH height loss in the unilateral PS + ISFP group that was not statistically significant (from 19.0 mm to 18.4 mm; 3.2% loss; P = 0.1). The analysis of segmental sagittal alignment, lumbar sagittal alignment, clinical outcomes, and fusion rates did not demonstrate any statistically significant differences.
  
  
  CONCLUSIONS
  Significantly reduced surgical invasiveness was associated with unilateral PS + ISFP fixation, which represents the major advantage of this technique. Unilateral fixation was also associated with a slightly lower reduction in FH and was equally effective as bilateral PS fixation in regard to fusion rates, clinical outcomes, and other radiographic outcomes studied.
authors.affiliation: Boulder Neurosurgical Associates, Boulder, Colorado, USA; Justin Parker Neurological Institute, Boulder, Colorado, USA.
authors.forename: Alan T
authors.initials: AT
authors.lastname: Villavicencio
authors.affiliation: Justin Parker Neurological Institute, Boulder, Colorado, USA.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Serxner
authors.affiliation: Boulder Neurosurgical Associates, Boulder, Colorado, USA; Justin Parker Neurological Institute, Boulder, Colorado, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Mason
authors.affiliation: Boulder Neurosurgical Associates, Boulder, Colorado, USA; Justin Parker Neurological Institute, Boulder, Colorado, USA.
authors.forename: E Lee
authors.initials: EL
authors.lastname: Nelson
authors.affiliation: Boulder Neurosurgical Associates, Boulder, Colorado, USA.
authors.forename: Sharad
authors.initials: S
authors.lastname: Rajpal
authors.affiliation: Justin Parker Neurological Institute, Boulder, Colorado, USA.
authors.forename: Nathan
authors.initials: N
authors.lastname: Faes
authors.affiliation: Boulder Neurosurgical Associates, Boulder, Colorado, USA; Justin Parker Neurological Institute, Boulder, Colorado, USA. Electronic address: sigitab@bnasurg.com.
authors.forename: Sigita
authors.initials: S
authors.lastname: Burneikiene
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000379:methods*; D007839:Functional Laterality; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000000981:diagnostic imaging / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D011446:Prospective Studies; D011859:Radiography; D013123:Spinal Fusion / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult
keywords: Foraminal height; Lumbar spine; Pedicle screws; Plate fixation; Transforaminal lumbar interbody fusion