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ObjectiveTo investigate the potential risk of approach-related complications at different access angles in minimally invasive lateral lumbar interbody fusion. MethodsEighty-six axial magnetic resonance images were obtained to analyze the risk of approach-related complications. The access corridor were simulated at different access angles and the potential risk of neurovascular structure injury was evaluated when the access corridor touching or overlapping the corresponding structures at each angle. Furthermore, the safe corridor length was measured when the corridor width was 18 and 22 mm. ResultsWhen access angle was 0°, the potential risk of ipsilateral nerve roots injury was 54.7% at L4–L5. When access angle was 45°, the potential risk of abdominal aorta, contralateral nerve roots or central canal injury at L4–L5 was 79.1%, 74.4%, and 30.2%, respectively. The length of the 18 mm-wide access corridor was largest at 0° and it could reach 44.5 mm at L3–L4 and 46.4 mm at L4–L5. While the length of the 22 mm-wide access corridor was 42.3 mm at L3–L4 and 44.1 mm at L4–L5 at 0°. ConclusionChanges in the access angle would not only affect the ipsilateral neurovascular structures, but also might adversely influence the contralateral neural elements. It should be also noted to surgeons that alteration of the access angle changed the corridor length.

To analyze the anatomical location of the ureter in relation to lateral lumbar interbody fusion and evaluate the potential risk of ureteral injury.Methods : 108 patients who performed contrast-enhanced computed tomographic scans were enrolled in this study. The location of the ureter from L2-L3 to L4-L5 was evaluated. The distances between the ureter and psoas muscle, intervertebral disc, and retroperitoneal vessels were also recorded bilaterally.Results : Over 30% of the ureters were close to the working corridor of XLIF at L2-L3. Most of the ureters were close to working corridor of OLIF, especially at L4-L5. The distance from the ureter to the great vessels on the left side was significantly narrowing from L2-L3 to L4-L5 (28.8±9.5mm, 22.0±8.0mm, 15.5±8.4mm), and it was significantly larger than that on the right side (12.3±6.1mm, 7.4±5.7mm, 5.4±4.4mm). Conclusion :Our findings indicate that the location of the ureter varies widely among individuals. To avoid unexpected damage to the ureter, it is imperative to directly visualize it and verify the ureter is not in the surgical pathway during lateral lumbar interbody fusion.