title: Comparison of perioperative outcomes following open versus minimally invasive transforaminal lumbar interbody fusion in obese patients.
abstract: OBJECTIVE
  Minimally invasive (MI) transforaminal lumbar interbody fusion (TLIF) has proven to be effective in the treatment of spondylolisthesis and degenerative disc disease (DDD). Compared with the traditional open TLIF, the MI procedure has been associated with less blood loss, less postoperative pain, and a shorter hospital stay. However, it is uncertain whether the advantages of an MI TLIF also apply specifically to obese patients. This study was dedicated to evaluating whether obese patients reap the perioperative benefits similar to those seen in patients with normal body mass index (BMI) when undergoing MI TLIF.
  
  
  METHODS
  Obese patients-that is, those with a BMI of at least 30 kg/m(2)-who had undergone single-level TLIF were retrospectively identified and categorized according to BMI: Class I obesity, BMI 30.0-34.9 kg/m(2); Class II obesity, BMI 35.0-39.9 kg/m(2); or Class III obesity, BMI ≥ 40.0 kg/m(2). In each obesity class, patients were stratified by TLIF approach, that is, open versus MI. Perioperative outcomes, including intraoperative estimated blood loss (EBL), complications (overall, intraoperative, and 30-day postoperative), and hospital length of stay (LOS), were compared. The chi-square test, Fisher exact test, or 2-tailed Student t-test were used when appropriate.
  
  
  RESULTS
  One hundred twenty-seven patients were included in the final analysis; 49 underwent open TLIF and 78 underwent MI TLIF. Sixty-one patients had Class I obesity (23 open and 38 MI TLIF); 45 patients, Class II (19 open and 26 MI); and 21 patients, Class III (7 open and 14 MI). Overall, mean EBL was 397.2 ml and mean hospital LOS was 3.7 days. Minimally invasive TLIF was associated with significantly less EBL and a shorter hospital stay than open TLIF when all patients were evaluated as a single cohort and within individual obesity classes. Overall, the complication rate was 18.1%. Minimally invasive TLIF was associated with a significantly lower total complication rate (11.5% MI vs 28.6% open) and intraoperative complication rate (3.8% MI vs 16.3% open) as compared with open TLIF. When stratified by obesity class, MI TLIF was still associated with lower rates of total and intraoperative complications. This effect was most profound and statistically significant in patients with Class III obesity (42.9% open vs 7.1% MI).
  
  
  CONCLUSIONS
  Minimally invasive TLIF offers obese patients perioperative benefits similar to those seen in patients with normal BMI who undergo the same procedure. These benefits include less EBL, a shorter hospital stay, and potentially fewer complications compared with open TLIF. Additional large retrospective studies and randomized prospective studies are needed to verify these findings.
authors.affiliation: University of Michigan Medical School, University of Michigan, Ann Arbor, MI 48109-5338, USA.
authors.forename: Darryl
authors.initials: D
authors.lastname: Lau
authors.forename: Adam
authors.initials: A
authors.lastname: Khan
authors.forename: Samuel W
authors.initials: SW
authors.lastname: Terman
authors.forename: Timothy
authors.initials: T
authors.lastname: Yee
authors.forename: Frank
authors.initials: F
authors.lastname: La Marca
authors.forename: Paul
authors.initials: P
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D016063:Blood Loss, Surgical; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008159:Lumbar Vertebrae; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods*; D009765:Obesity / Q000150:complications* / Q000601:surgery*; D011183:Postoperative Complications / Q000209:etiology*; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000379:methods*