Pseudarthrosis Following Lumbar and Lumbosacral Fusion Using the Antepsoas Technique.

STUDY DESIGN: Retrospective case-control study. OBJECTIVE: The aim of this study was to evaluate the prevalence of pseudarthrosis following antepsoas (ATP) lumbar and lumbosacral fusions. SUMMARY OF BACKGROUND DATA: Pseudarthrosis is a feared complication following spinal fusions and may affect their clinical outcomes. To date there are no sufficient data on the fusion rate following ATP lumbar and lumbosacral arthrodesis. METHODS: This is a retrospective review of 220 patients who underwent lumbar minimally invasive antepsoas (MIS-ATP) fusions between January 2008 and February 2019 who have at least 1-year postoperative computed tomography (CT) follow-up scans. Fusion was graded using CT scans imaging and adopting a 1-4 grading scale (1, definitely fused; 2, likely fused; 3, likely not fused; 4, definitely not fused/nonunion). Grades 3 or 4 indicate pseudarthrosis. RESULTS: A total of 220 patients (average age: 66 years, 82 males (37.2%), and 127 (57.7%) smokers) were included. Eight patients (3.6%) developed pseudarthrosis. A total of 693 discs were addressed using the ATP approach. Of those, 681 (98.3%) were considered fused (641 levels [92.5%] were "definitely fused" and 40 levels [5.8%] were "Likely fused") and 12 discs (1.7%) developed pseudarthrosis (seven levels [1.0%] were "likely not fused" and five levels (0.7%) were "definitely not fused"). The highest rate of pseudarthrosis was found at L5-S1 (4.8%) compared to the L1-L5 discs (0-2%). Of 127 smokers, six developed pseudarthrosis (odds ratio = 2.3, P = 0.3). The fusion rates were 95.3% and 97.8% for smokers and nonsmokers, respectively. Of the eight patients who developed pseudarthrosis, only four (50%) were symptomatic, of whom two (25%) required revision surgery. Both of these patients were smokers. The overall revision rate due to pseudarthrosis was 0.9% (two of 220 patients). CONCLUSION: The MIS-ATP technique results in a high fusion rate (96.4% of patients; 98.3% of levels). Pseudarthrosis was noted mostly at the L5-S1 discs and in smokers.Level of Evidence: 4.