title: The impact of minimally invasive spine surgery on perioperative complications in overweight or obese patients.
abstract: OBJECTIVE
  Open lumbar spinal surgery in overweight or obese patients has been associated with increased risk of perioperative complications. The impact of minimally invasive spinal (MIS) surgery on the incidence of perioperative adverse events in overweight or obese patients, however, has not been well evaluated.
  
  
  METHODS
  A retrospective review of consecutive patients undergoing lumbar MIS surgery from January 2006 to April 2007 was performed. Of the 77 patients identified, 56 had a body mass index (BMI) of 25.0 kg/m2 or greater.
  
  
  RESULTS
  Of the 56 patients with a BMI of 25 kg/m2 or greater, 32 (57.1%) were men; the mean age was 54.1 years. The mean BMI was 31.0 kg/m2 (range, 25.1-43.8 kg/m2). Using a broad definition of an adverse event, eight (14.3%) complications were identified. In the discectomy/laminotomy subgroup (31 patients), two (6.5%) adverse events were noted. In the fusion subgroup (25 patients), six (24%) adverse events were noted, most of which were minor. Of the 21 patients with a BMI less than 25 kg/m2, eight (38.1%) were men, and the mean age was 43.7 years. The mean BMI was 22.5 kg/m2 (range, 16.8-24.6 kg/m2). Three (14.3%) complications were noted overall. In the discectomy/laminotomy subgroup (17 patients), two (11.8%) adverse events occurred. One (25%) complication developed in the four patients making up the fusion subgroup. There was no statistically significant difference in complication rates between groups. Logistic regression also found no statistically significant relationship between BMI and perioperative complications.
  
  
  CONCLUSIONS
  There does not appear to be an increased risk of developing perioperative complications in overweight or obese patients undergoing MIS surgery, which may reflect a potential benefit of the MIS approach.
authors.affiliation: Department of Neurosurgery, University of Michigan Health System, Ann Arbor, Michigan 48109-5338, USA. ppark@umich.edu
authors.forename: Paul
authors.initials: P
authors.lastname: Park
authors.forename: Cheerag
authors.initials: C
authors.lastname: Upadhyaya
authors.forename: Hugh J L
authors.initials: HJ
authors.lastname: Garton
authors.forename: Kevin T
authors.initials: KT
authors.lastname: Foley
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017586:Diskectomy / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007796:Laminectomy / Q000009:adverse effects*; D008159:Lumbar Vertebrae / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects*; D009765:Obesity / Q000601:surgery*; D050177:Overweight / Q000601:surgery; D019990:Perioperative Care; D012189:Retrospective Studies; D018570:Risk Assessment; D013119:Spinal Cord Injuries / Q000209:etiology* / Q000517:prevention & control; D013123:Spinal Fusion / Q000009:adverse effects*; D016896:Treatment Outcome