title: Micro vs. macrodiscectomy: Does use of the microscope reduce complication rates?
abstract: OBJECTIVE
  A single level discectomy is one of the most common procedures performed by spine surgeons. While some practitioners utilize the microscope, others do not. We postulate improved visualization with an intraoperative microscope decreases complications and inferior outcomes.
  
  
  METHODS
  A multicenter surgical registry was utilized for this retrospective cohort analysis. Patients with degenerative spinal diagnoses undergoing elective single level discectomies from 2010 to 2014 were included. Univariate analysis was performed comparing demographics, patient characteristics, operative data, and outcomes for discectomies performed with and without a microscope. Multivariable logistic regression analysis was then applied to compare outcomes of micro- and macrodiscectomies.
  
  
  RESULTS
  Query of the registry yielded 23,583 patients meeting inclusion criteria. On univariate analysis the microscope was used in a greater proportion of the oldest age group as well as Hispanic white patients. Patients with any functional dependency, history of congestive heart failure, chronic corticosteroid use, or anemia (hematocrit<35%) also had greater proportions of microdiscectomies. Thoracic region discectomies more frequently involved use of the microscope than cervical or lumbar discectomies (25.0% vs. 16.4% and 13.0%, respectively, p<0.001). Median operative time (IQR) was increased in microscope cases [80min (60, 108) vs. 74min (54, 102), p<0.001]. Of the patients that required reoperation within 30days, 2.5% of them had undergone a microdiscectomy compared to 1.9% who had undergone a macrodiscectomy, p=0.044. On multivariable analysis, microdiscectomies were more likely to have an operative time in the top quartile of discectomy operative times, ≥103min (OR 1.256, 95% CI 1.151-1.371, p<0.001). In regards to other multivariable outcome models for any complication, surgical site infection, dural tears, reoperation, and readmission, no significant association with microdiscectomy was found.
  
  
  CONCLUSIONS
  The use of the microscope was found to significantly increase the odds of longer operative time, but not influence rates of postoperative complications. Thus, without evidence from this study that the microscope decreases complications, the use of the microscope should be at the surgeon's discretion, validating the use of both macro and micro approaches to discectomy as acceptable standards of care.
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, 200 1st St. SW, Rochester, MN, 55905, USA; Mayo Clinic Neuro-Informatics Laboratory, Mayo Clinic, Rochester, Minnesota, 200 1st St. SW, Rochester, MN, 55905, USA. Electronic address: Murphy.Meghan@mayo.edu.
authors.forename: Meghan E
authors.initials: ME
authors.lastname: Murphy
authors.affiliation: Mayo Clinic Neuro-Informatics Laboratory, Mayo Clinic, Rochester, Minnesota, 200 1st St. SW, Rochester, MN, 55905, USA; Mayo Medical School, Mayo Clinic, Rochester, Minnesota, 200 1st St. SW, Rochester, MN, 55905, USA. Electronic address: Hakim.Jeffrey@mayo.edu.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Hakim
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, 200 1st St. SW, Rochester, MN, 55905, USA; Mayo Clinic Neuro-Informatics Laboratory, Mayo Clinic, Rochester, Minnesota, 200 1st St. SW, Rochester, MN, 55905, USA. Electronic address: Kerezoudis.Panagiotis@mayo.edu.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Kerezoudis
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, 200 1st St. SW, Rochester, MN, 55905, USA; Mayo Clinic Neuro-Informatics Laboratory, Mayo Clinic, Rochester, Minnesota, 200 1st St. SW, Rochester, MN, 55905, USA.
authors.forename: Mohammed Ali
authors.initials: MA
authors.lastname: Alvi
authors.affiliation: Department of Health Sciences Research, Mayo Clinic, Rochester, MN, 200 1st St. SW, Rochester, MN, 55905, USA. Electronic address: Ubl.Dan@mayo.edu.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Ubl
authors.affiliation: Department of Health Sciences Research, Mayo Clinic, Rochester, MN, 200 1st St. SW, Rochester, MN, 55905, USA. Electronic address: Habermann.Elizabeth@mayo.edu.
authors.forename: Elizabeth B
authors.initials: EB
authors.lastname: Habermann
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, 200 1st St. SW, Rochester, MN, 55905, USA; Mayo Clinic Neuro-Informatics Laboratory, Mayo Clinic, Rochester, Minnesota, 200 1st St. SW, Rochester, MN, 55905, USA. Electronic address: Bydon.Mohamad@mayo.edu.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Bydon
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017586:Diskectomy / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008866:Microsurgery / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data*; D008875:Middle Aged; D010043:Outcome and Process Assessment, Health Care / Q000706:statistics & numerical data*; D011183:Postoperative Complications / Q000453:epidemiology*; D012042:Registries / Q000706:statistics & numerical data*; D012189:Retrospective Studies
keywords: Discectomy; Macrodiscectomy; Microdiscectomy; Microscope; Outcomes