title: Primary Versus Revision Single-level Minimally Invasive Lumbar Discectomy: Analysis of Clinical Outcomes and Narcotic Utilization.
abstract: METHODS
  Retrospective cohort analysis of a prospectively maintained registry.
  
  
  OBJECTIVE
  To compare the intraoperative variables, surgical outcomes, and narcotic utilization between primary and revision 1-level minimally invasive (MIS) lumbar discectomies.
  
  
  BACKGROUND
  Revision spine surgery may be associated with longer procedural time and greater soft tissue disruption. Few studies have analyzed the surgical outcomes and narcotic utilization associated with MIS revision lumbar discectomies.
  
  
  METHODS
  A retrospective analysis of 227 consecutive cases of MIS 1-level lumbar discectomy for degenerative spinal pathology between 2009 and 2014 by a single surgeon was performed. Patients were stratified into primary and revision cohorts. Demographics, comorbidity, intraoperative parameters, peri- and postoperative outcomes, and reoperations were assessed. Postoperative narcotic utilization was compared between cohorts. Statistical analyses were performed using Student t-test and Pearson χ test. A P < 0.05 denoted statistical significance.
  
  
  RESULTS
  Of the 227 cases included, 186 patients (81.9%) and 41 patients (18.1%) were included in the primary and revision cohorts, respectively. Demographics, comorbidity, smoking status, preoperative visual analogue scale (VAS) scores, and estimated blood loss did not differ between cohorts. However, the revision cohort demonstrated a longer procedural time, increased length of hospitalization, and higher postoperative narcotic utilization. Although not statistically significant, revision patients trended toward higher 6-week postoperative VAS scores and reherniation rates. In addition, revision patients were more likely to undergo subsequent lumbar fusion than primary patients.
  
  
  CONCLUSIONS
  The findings suggest that revision MIS lumbar discectomy may be associated with increased procedural time, increased length of hospitalization, and increased postoperative narcotic utilization. Whereas revision patients trended toward higher postoperative VAS scores at 6 weeks, both cohorts demonstrated similar pain levels at final follow-up. Finally, revision patients may be at a greater risk of reherniation and subsequent reoperation. Further studies are warranted to characterize the independent risk factors for a revision lumbar discectomy.
  
  
  METHODS
  3.
authors.affiliation: *Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL; and †Department of Orthopaedics and Rehabilitation, Yale School of Medicine, New Haven, CT.
authors.forename: Junyoung
authors.initials: J
authors.lastname: Ahn
authors.forename: Ehsan
authors.initials: E
authors.lastname: Tabaraee
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Bohl
authors.forename: Khaled
authors.initials: K
authors.lastname: Aboushaala
authors.forename: Kern
authors.initials: K
authors.lastname: Singh
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid / Q000627:therapeutic use*; D001416:Back Pain / Q000175:diagnosis / Q000188:drug therapy* / Q000209:etiology; D016009:Chi-Square Distribution; D017586:Diskectomy / Q000009:adverse effects* / Q000379:methods*; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000503:physiopathology / Q000601:surgery*; D007902:Length of Stay; D008159:Lumbar Vertebrae / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D010147:Pain Measurement; D010149:Postoperative Pain / Q000175:diagnosis / Q000188:drug therapy* / Q000209:etiology; D012042:Registries; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid