Anatomical Positional Variations of Retroperitoneal Organs and Lumbar Lordosis Angle Changes During Single-Position Prone Lateral Lumbar Interbody Fusion in Diverse Intraoperative Decubitus

Study Design Retrospective case series.Objective The single-position prone lateral lumbar interbody fusion (P-LLIF), which eliminates the need to change patient decubitus during the procedure, represents a modification of the traditional lateral lumbar interbody fusion (LLIF). This pioneering study aims to investigate the positional shifts of retroperitoneal organs and changes in lumbar lordosis angle across different decubitus, providing novel insights into the biomechanics of LLIF.Methods Eighteen patients scheduled for LLIF were included. CT scans were performed in 3 positions: prone, right lateral, and oblique decubitus. Measurements included the anatomical positions of the psoas major, abdominal aorta, left common iliac artery, and left kidney at intervertebral disc levels, as well as changes in lumbar lordosis angle across the 3 positions.Results In the prone decubitus compared to the lateral decubitus: The thickness of the psoas major increased by 4.07 +/- 3.41 mm. The abdominal aorta shifted laterally by 2.29 +/- 2.79 mm. The left common iliac artery shifted laterally by 1.98 +/- 3.54 mm. The kidney moved anteriorly by 6.97 +/- 5.84 mm. The lumbar lordosis angle increased by 7.73 +/- 3.76 degrees. In the oblique decubitus compared to the lateral decubitus: The thickness of the psoas major increased by 3.14 +/- 3.36 mm. The abdominal aorta shifted laterally by 1.59 +/- 2.82 mm. The left common iliac artery shifted laterally by 2.45 +/- 4.51 mm. The kidney moved anteriorly by 3.92 +/- 4.70 mm. The lumbar lordosis angle increased by 3.04 +/- 3.55 degrees.Conclusion P-LLIF induces significant positional changes in retroperitoneal organs and increases lumbar lordosis angle compared to traditional LLIF. These findings offer critical insights for preoperative planning and underscore the importance of optimizing safety protocols in P-LLIF procedures.