Objectives: To review the surgical results and to identify possible parameters influencing the clinical outcomes in an unselected patient collective undergoing minimally invasive lumbar interbody fusion in a spinal care unit. Methods: A total of 229 adult patients who underwent minimally invasive lumbar spinal fusion between 2008 and 2016 were included in this retrospective analysis. Lumbar fusion was performed using transforaminal interbody fusion (TLIF) devices and posterolateral fusion. To eliminate confounding parameters, in all patients interbody fusion was indicated by lumbar degenerative pathologies, and surgery was performed using the same fusion device. Treatment efficacy was evaluated using scores describing pain (visual analogue scale [VAS]) and health impairment (EQ-5D, Oswestry Disability Index [ODI]). The influence of patient age, obesity, active smoking status, and co-morbidities on clinical outcome and perioperative complications was analyzed. Results: The patient population reviewed had improved VAS (P-(leg pain) <= 0.0001, P-(back pain) <= 0.0001), ODI (P <= 0.0001), EQ-VAS (P <= 0.0001), and EQ-5D subscales "mobility", "self-care", "pain", and "anxiety" (P-(mobility) <= 0.0001, P(self-care) = 0.41, P-(pain) <= 0.0001, P-(anxiety) = 0.011) postoperatively. Neither advanced patient age, nor increased body mass index (BMI), hypertension, or active smoking status had a significantly limiting influence on the success of minimally invasive spinal surgeries (MIS). Duration of surgery strongly correlated with the number of spinal levels treated and with intraoperative blood loss (r = 0.774, P <= 0.0001, n = 208). Weak positive correlations were found between patient age and duration of surgery (r = 0.184, P = 0.005, n = 229), intraoperative blood loss (r = 0.165, P = 0.012, n = 229), and duration of hospitalization (r = 0.270, P <= 0.0001, n = 228), respectively. When compared to non-smokers, smokers were younger (P <= 0.0001), and had a significantly lower BMI (P = 0.001), shorter durations of surgery (P <= 0.0001), decreased intraoperative blood loss (P = 0.022), and shorter hospital stays (P = 0.006), respectively. Complications occurred in 17 patients (7%) and were not affected by patient age, BMI, hypertension, or active smoking status. Conclusion: Minimally invasive spinal surgery is a safe and effective treatment option and may be superior to open surgery in subpopulations with significant co-morbidities and risk factors, such as elderly and obese patients as well as patients with an active smoking status.
