title: The effect of surgical level on self-reported clinical outcomes after minimally invasive transforaminal lumbar interbody fusion: L4-L5 versus L5-S1.
abstract: OBJECTIVE
  The anatomic and biomechanical aspects of the L5-S1 level present unique operative challenges compared with the L4-L5 level. However, it has not been determined if self-reported outcomes and complications are different between patients treated with a minimally invasive transforaminal lumbar interbody fusion at these specific levels.
  
  
  METHODS
  There were 36 consecutive patients identified who were treated with a minimally invasive transforaminal lumbar interbody fusion procedure. Surgical indications included spondylolisthesis (grade 1 or 2) and degenerative disk disease with associated clinical symptoms. Patients completed a visual analog scale (VAS) for their back and leg and Oswestry Disability Index preoperatively and postoperatively. Outcomes were compared between patients with L4-L5 involvement and patients with L5-S1 involvement. In all patients, fusion was evaluated by dynamic view flexion and extension views at 1 year. In all patients with indeterminate results or incomplete imaging, computed tomography was performed to evaluate for bridging bone and stable hardware positioning.
  
  
  RESULTS
  The surgical indications between the 2 groups were similar (χ(2) = 0.089, df = 2, P = 0.956). There was no significant difference in mean operating time, intraoperative blood loss, and hospital stay (P = 0.937, 0.627, and 0.587). There was no significant difference in the long-term postoperative questionnaire results (P = 0.819 for VAS [back], 0.626 for VAS [leg], and 0.962 for Oswestry Disability Index) or the mean preoperative to postoperative change in Cobb angle (P = 0.626) between the 2 groups. Two complications, one in each group, were a rash from an antibiotic and postoperative nausea.
  
  
  CONCLUSIONS
  Despite differences in biomechanics and unique anatomic challenges at the L5-S1 interspace, there is no difference in self-reported outcomes for patients treated with minimally invasive transforaminal lumbar interbody fusion at the L4-L5 level compared with the L5-S1 level.
authors.affiliation: Department of Neurological Surgery, Northwestern University, Chicago, Illinois, USA.
authors.forename: Cort D
authors.initials: CD
authors.lastname: Lawton
authors.affiliation: Department of Neurological Surgery, Northwestern University, Chicago, Illinois, USA.
authors.forename: Zachary A
authors.initials: ZA
authors.lastname: Smith
authors.affiliation: Department of Neurological Surgery, Northwestern University, Chicago, Illinois, USA.
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Nixon
authors.affiliation: Department of Neurological Surgery, Northwestern University, Chicago, Illinois, USA.
authors.forename: Nader S
authors.initials: NS
authors.lastname: Dahdaleh
authors.affiliation: Department of Neurological Surgery, Northwestern University, Chicago, Illinois, USA.
authors.forename: Albert P
authors.initials: AP
authors.lastname: Wong
authors.affiliation: Department of Neurological Surgery, Northwestern University, Chicago, Illinois, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Khanna
authors.affiliation: Department of Neurological Surgery, Northwestern University, Chicago, Illinois, USA.
authors.forename: Abdulwahed
authors.initials: A
authors.lastname: Barnawi
authors.affiliation: Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois, USA. Electronic address: rfessler@rush.edu.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Fessler
mesh_terms: D000368:Aged; D001863:Bone Screws; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000473:pathology / Q000601:surgery; D008141:Lordosis / Q000473:pathology / Q000601:surgery; D008159:Lumbar Vertebrae / Q000601:surgery*; D008160:Lumbosacral Plexus; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods*; D019635:Neurosurgical Procedures / Q000379:methods*; D010147:Pain Measurement; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D057566:Self Report; D013123:Spinal Fusion / Q000379:methods*; D013168:Spondylolisthesis / Q000473:pathology / Q000601:surgery; D016896:Treatment Outcome
keywords: Different levels; Minimally invasive surgery; Minimally invasive transforaminal lumbar interbody fusion; Outcomes; Spine surgery; Transforaminal lumbar interbody fusion