Introduction: The lateral approach to the lumbar spine has the advantages of improving accessibility to anterior spinal body that facilitates minimum invasive treatment by transpsoas approach. By using the expandable retractors that are positioned under fluoroscopic guidance, the lateral approach provides direct vision of the operative field; although it is narrow than the vision of standard open anterior approach. Risks of this technique include injury to the exiting nerve root and retroperitoneal vessels. Herein, authours conducted morphometric analysis, using magnetic resonance imaging (MRI) studies of the lumbar spine among Korean population.

Methods: Fifty one lumbar spine MRI studies were reviewed from patients treated for various spinal pathologies. The measured intervertebral segments were divided into group 1 (normally aligned vertebrae and disc spaces, n=211) or group 2 (degenerative spondylolisthetic segments, n=26). Axial MR images were used to measure: the vertebral endplate anterior-posterior diameter, the overlap between the ventral root and the posterior margin of the vertebra, and the overlap between the retroperitoneal large vessels and the anterior edge of the vertebra. The result also compared to the result of the previous reports.

Results: The safe zone between the adjacent neuro-vascular structures and the vertebral body endplate gradually narrowed from L1–L2 to L5–S1, and was observed wider in left side than right side. There were no significant differences in the position of the nerve roots, or retroperitoneal vessels, between group 1 and group 2 patients. The result of safe zone among Korean was more wider than the previous reports among European and American.

Conclusions: The safe corridor for the lateral approach to perform the discectomy and interbody fusion narrows from L1–L2 to the L5–S1 level, and more wider zone achieves by left appoach in Korean population. The safe zone is also changed by the ethnicity, more wider zone in Asian than European and American.

Patient Care: The result of safe zone among Korean was wider than the previous reports among European and American. Herein, the lateral approach to the lumbar spine has the advantages of minimal invasive treatment without lesser risks of injury to the exiting nerve root and retroperitoneal vessels in Asian ethics.

Learning Objectives: The safe zone between the adjacent neuro-vascular structures and the vertebral body endplate gradually narrowed from L1–L2 to L5–S1, and was observed wider in left side than right side. The safe zone area was differently checked according to the ethics.

References: Surg Radiol Anat. (2011) 33:665-671 Spine. (2009) 34(12):1330-1335 Korean J Spine (2012) 9(3):176-180