Anatomic Relationship Between Ureter and Oblique Lateral Interbody Fusion Access: Analysis Based on Contrast-Enhanced Computed Tomographic Urography.

Objective: To investigate the anatomic relationship between ureter and oblique lateral interbody fusion access by using contrast-enhanced computed tomographic urography.

Methods: Contrast-enhanced computed tomographic urography data of 234 patients were retrospectively analyzed. The angle of inclination (∠α) of bilateral ureters, the angle between bilateral surgical accesses (∠β), the insertion angle of surgical access (∠γ), and the angle between ureter and outer margin of ipsilateral surgical access (∠ε) at L2/3, L3/4, and L4/5 levels were measured and analyzed.

Results: ∠α gradually increased from L2/3 to L4/5. ∠β gradually decreased from L2/3 to L4/5, and at each level the left-sided ∠β was larger than right-sided ∠β. ∠ε were positive at L2/3 and left-sided L3/4. The right-sided ∠ε at L3/4 and the bilateral sided ∠ε at L4/5 were negative, and the right-sided ∠ε at L4/5 had the largest absolute value.

Conclusions: The bilateral ureters gradually descents from the lateral margin to the anteromedial margin on the surface of psoas major muscle. The range of bilateral surgical accesses for oblique lateral interbody fusion gradually decreases from L2/3 to L4/5, and the left-sided access is larger than the right-sided when at the same level. Ureters at the right-sided L3/4 level and bilateral L4/5 levels are at high risk of being injured. In particular, the right ureter at the L4/5 level is most likely to be injured.