General Session: MIS-2
Presented by: A. Narain - View Audio/Video Presentation (Members Only)
A. Narain(1), F. Hijji(1), K. Yom(1), K. Kudaravalli(1), K. Singh(1)
(1) Rush University Medical Center, Orthopaedic Surgery, Chicago, IL, United States
Introduction: Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is a common and effective treatment for lumbar degenerative disorders. Within the orthopaedic literature, increasing body mass index (BMI) has been associated with increased rates of postoperative complications and necessity for revision procedures. However, few studies have analyzed the association between BMI and the risk for revision surgery following minimally invasive spinal procedures. As such, the purpose of this study is to determine the association between BMI and the rate of revision surgery after single-level MIS TLIF.
Methods: A prospectively maintained surgical database of patients who underwent a single-level MIS TLIF for degenerative pathology between 2005-2014 was reviewed. Patients were stratified based on BMI category: normal weight (BMI < 25), overweight (BMI 25-30), obese I (BMI 30-35), and obese II-III (BMI ≥ 35). BMI category was tested for association with demographic and procedural characteristics using one-way analysis of variance (ANOVA), chi-squared analysis, and fisher's exact test for continuous, categorical, and non-parametric variables, respectively. BMI category was tested for an association with undergoing a revision procedure within 2 years after MIS TLIF using Poisson regression with robust error variance. Finally, multivariate analysis using Poisson regression with robust error variance was used to test for an association between demographic characteristics and undergoing a revision procedure within 2 years.
Results: 237 patients were included in this analysis; of these, 45 (18.99%) were normal weight, 87 (36.71%) were overweight, 52 (21.94%) were obese I, and 52 (21.94%) were obese II-III. Overweight and obese I groups has a higher percentage of males (Normal: 44.46% vs. Overweight: 65.52% vs. Obese I: 61.54% vs. Obese II: 37.74%, p=0.004). Additionally, Obese I and Obese II-III groups had longer operative times (Normal: 108.91 vs. Overweight: 102.45 vs. Obese I: 115.69 vs. Obese II: 121.12 minutes, p=0.018). On bivariate and multivariate analysis, BMI category was not associated with undergoing a revision procedure within 2 years after MIS TLIF (p=0.674). On multivariate analysis, younger age (p=0.004) was associated with increased risk of undergoing a revision procedure after MIS TLIF.
Conclusions: The results of this study suggest that increasing body mass index is not a risk factor for undergoing a revision procedure after MIS TLIF. As such, patients with high BMI should be counseled regarding having similar rates of operative success and similar probabilities of needing a reoperation after MIS TLIF as those with lower BMI.