Minimally Invasive versus Conventional Lumbar Interbody Fusion at L5–S1: A Retrospective Comparative Study

Objective: This study aimed to evaluate the radiologic and clinical outcomes of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and conventional posterior lumbar interbody fusion (PLIF) at the L5–S1.Methods: We retrospectively reviewed patients who underwent posterior lumbar fusion (MIS-TLIF and PLIF) at only the L5–S1 and were followed up for more than 12 months. Age, sex, body mass index (BMI), bone mineral density (BMD), diagnosis, comorbid conditions, fusion rate, perioperative results, and pre- and postoperative radiographic parameters at the L5–S1 level, pelvic parameters and degree of spondylolisthesis, and clinical results were analyzed.Results: A total of 102 patients (46 male, 56 female) with a mean age of 57.1 years were evaluated. Fifty and fifty-two patients underwent MIS-TLIF and PLIF surgeries, respectively. Radiologic parameters increased from their preoperative measures at the last follow-up study; similarly, there were no intergroup differences. The fusion rates in the MIS-TLIF and PLIF groups were 86% and 82.7%, respectively. The subsidence rates in the MIS-TLIF and PLIF groups were 6% and 3.8%, respectively. There was no intergroup difference in terms of fusion rate and subsidence. Clinical outcomes also gradually improved after surgery in both groups without intergroup differences.Conclusion: In L5–S1 posterior spinal surgery, there was no significant difference between MIS-TLIF and conventional PLIF. Considering the operation time and estimated blood loss, MIS-TLIF is more effective than PLIF surgery in terms of postoperative health care and economics.