1537. Defining the MIS-TLIF: A Systematic Review of the Techniques Reported by Surgeons Worldwide

Authors: Robert Nick Hernandez, MD; Sara Lener, MD; Christoph Wipplinger, MD; Sertac Kirnaz, MD; Rodrigo Navarro-Ramirez, MD; Roger Hartl, MD (Cranford, NJ)

Background: Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is an increasingly popular procedure. However, there is no standard definition agreed upon by minimally invasive spine surgeons and consequently there are many variations on how the MIS-TLIF is performed. Materials and Methods: A systematic review was performed to examine the MIS-TLIF techniques reported in the existing body of literature to help provide a definition of the MIS-TLIF. Results: We identified 75 articles that met inclusion criteria, reporting on a total of 4,920 patients undergoing MIS-TLIF. Overall, there was great heterogeneity in many aspects of the MIS-TLIF. We did, however, identify several patterns that seemed agreed upon by MIS surgeons. 90% of all studies utilized incisions off midline. 79% reported the use of standard fluoroscopy for intraoperative imaging and only 13% used computer-assisted navigation. 81% used a tubular retractor, either expandable or nonexpendable. When graft material was used, 95% and 91% used autograft with or without allograft or bone graft substitute to pack the anterior disc space and interbody cage, respectively. 79% performed percutaneous/percfascial placement of pedicle screws and 75% placed bilateral pedicle-screw rod constructs. Of the studies that reported details of achieving bilateral decompression, 93% did so via unilateral laminotomy for bilateral decompression. Importantly, we identified several aspects that may disqualify a TLIF from being labeled as MIS: midline incision, lack of microscope or endoscope use, expandable retractor use, and lack of percutaneous placement of the pedicle screw-rod constructs. The retractor type appeared to have the greatest impact on the degree of invasiveness. Conclusion: There is considerable heterogeneity with regard to the techniques used for the performance of MIS-TLIF, however we did identify several components agreed upon by MIS surgeons. A definition of the MIS-TLIF is needed in order to optimize the MIS-TLIF technique, for future research, and for patient education.