Study design:

Retrospective case-control study.

Objective:

To evaluate the prevalence of pseudarthrosis following 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 is no sufficient data on the fusion rate following antepsoas (ATP) lumbar and lumbosacral arthrodesis.

Methods:

This is a retrospective review of 220 patients who underwent lumbar MIS-ATP fusions between January 2008 and February 2019 who have at least one-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 Male (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 [7 levels (1.0%) were “likely not fused” and 5 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, 6 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 4 (50%) were symptomatic, of whom 2 (25%) required revision surgery. Both of these patients were smokers. The overall revision rate due to pseudarthrosis was 0.9% (2/220 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.