Minimally invasive posterior lumbar surgery in the morbidly obese, obese and non-obese populations: A single institution retrospective review

Background: There is a paucity of information regarding outcomes in minimally invasive surgical (MIS) approaches to posterior lumbar surgery in morbidly obese patients. We seek to determine if there are differences in operative variables and early complication rates in morbidly obese patients undergoing MIS posterior lumbar surgery compared to obese and non-obese patients. Methods: A single institution retrospective review of patients undergoing MIS posterior lumbar surgery (decompression and/or fusion) between 2013 and 2016 was performed. Morbidly obese patients (BMI > 40) were compared to obese (BMI 30-39.9) and non-obese (BMI < 30) cohorts. Postoperative complication rates and perioperative variables including estimated blood loss, operative time, and outcome measures including length of stay (LOS), in-hospital complications, readmission, and disposition were assessed. Results: 47 morbidly obese, 135 obese and 224 non-obese patients underwent posterior MIS instrumented fusion. 59 morbidly obese, 182 obese and 314 non-obese patients underwent posterior MIS decompression. The morbidly obese group experienced a greater rate of deep vein thrombosis and had an increased hospital LOS (p < 0.05). Morbidly obese patients who underwent MIS decompression experienced increased postoperative complications (p < 0.01), and increased LOS (p < 0.0001) compared to obese and non-obese patients. There were no differences in revision rates, readmissions, and other complications including surgical site infection. Morbid obesity was an independent predictor of overall complications and increased LOS on multivariate analysis. Conclusion: Morbidly obese patients undergoing posterior MIS fusion had a higher rate of complications and increased LOS. While weight loss should be encouraged, complication rates remains acceptably low in morbidly obese patients and MIS posterior lumbar surgery should still be offered.