The Relevant Anatomy of the Approach for Axial Lumbar Interbody Fusion

Study Design. Prospective trial. Objective. To perform a precise anatomical study of the presacral space and to examine the approach safety of AxiaLIF (axial lumbar interbody fusion) in an anatomical aspect. Summary of Background Data. AxiaLIF is a novel, minimally invasive surgery. Though there were a few clinical reports on its safety, AxiaLIF is less used in current practice because of the unfamiliarity of surgeons with the regional anatomy of presacral space. Methods. Sixteen adult cadaveric pelvic specimens were divided along the median sagittal plane. The presacral fascial structures, the rectosacral fascia, and the pelvic splanchnic nerves were dissected and measured. In the simulated operation, a blunt guide pin was inserted bilaterally to determine the relation of the guide pin's path with important anatomic structures. Mean distances with 95% confidence intervals (CIs) were calculated. Results. The results showed that the fascial structures of the presacral space were divided into 5 layers, and the pelvic splanchnic nerves limited the dissection of the lower rectum, the mean length of which was 2.2 cm (1.9-2.5 cm). In the simulated operation, the mean minimum distance from the guide pin to the pelvic splanchnic nerves was 0.8 cm (0.4-1.2 cm), and the mean vertical distance to the S3-S4 junction was 1.5 cm (1.2-1.7 cm). Conclusion. Our study suggests that the approach for AxiaLIF is risky and requires further modification. We should choose the accurate surgical plane when performing the presacral approach.