MIS-TLIF: Technical note, Learning goals behind case selection during early part of learning curve and clinical outcomes in first 150 cases

Abstract

Introduction: Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS-TLIF) has been shown to offer several advantages over conventional (open) TLIF and is being increasingly employed by young surgeons early in their careers. It is important to know the appropriate technique and the correct cases to be selected in the early phase to achieve good outcomes during the learning curve. A detailed and illustrative technical note along with a guide for case selection at different phases of experience has been presented in this article. Methods: The first consecutive single surgeon series of 150 MIS-TLIF cases done over 4 years between 2012 and 2015 were considered for analysis. Demographic and peri-operative data and previously documented follow-up were collected from case records. Telephonic questionnaire and consultation were done to collect latest status, any procedures/surgeries done elsewhere for issues related to index procedure. Results were stratified as Group 1 – first 25 cases; Group 2 – 26–75 cases; Group 3 – 76–150 cases. Results: The major indication for surgery in group 1 was either Grade 1 spondylolisthesis or lumbar canal stenosis with concomitant axial symptoms. The incidence of relatively complex cases (Grade 2 or 3 listhesis; Revision cases; Multilevel cases) increased with each successive group. As expected, the operative time (calculated for only single-level cases) improved with time. The overall rate of peri-operative complications was higher in group 2 as compared to groups 1 and 3, predominantly due to an increased incidence of intra-operative dural tears in group 2. Symptomatic screw malposition was detected in five screws, all were managed conservatively. The median duration of follow-up for the entire group was 39 months (Range – 1–119 months). Eighty-two (55%) patients had follow-up of more than 1 year while 31 (20.6%) patients had follow-up of more than 7 years. Around 80–85% of patients at each point of follow-up assessment had a successful outcome (McNab 4 and 5). The re-operation rate for index level problems or adjacent segment was 2.6%, only one of which was done at the author’s center. Conclusions: Minimally invasive TLIF is a safe and effective procedure with favorable long-term results and acceptable complication rates. Though technically challenging in initial phases, a good understanding of the technique and principles of minimally invasive spine surgery along with fulfilling helpful pre-requisites and appropriate case selection as mentioned in this article, will help to smoothen the learning curve and avoid unfavorable outcomes in early stages.