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An Anatomic Study of the Lumbar Plexus with Respect to Retroperitoneal Endoscopic Surgery

Moro, Takatomo MD*; Kikuchi, Shin-ichi MD, PhD*; Konno, Shin-ichi MD, PhD*; Yaginuma, Hiroyuki MD, PhD

doi: 10.1097/01.BRS.0000049226.87064.3B

Study Design. The distribution of the lumbar plexus was analyzed using cadavers.

Objective. To clarify the safety zone to prevent nerve injuries with respect to retroperitoneal endoscopic surgery.

Summary of Background Data. Surgical approaches to the retroperitoneal space vary among surgeons. Recently, retroperitoneal endoscopic surgery has been applied to various spinal disorders. When the psoas major muscle is separated during retroperitoneal endoscopic surgery, there is a potential risk of injury to the lumbar plexus or nerve roots. However, there is sparse knowledge regarding the relationship between the greater psoas muscle and the lumbar plexus.

Methods. A total of 30 cadavers were analyzed. Six lumbar spines of the cadavers were cut in parallel with the lumbar disc space. Each axial section was photographed and captured into a computer. The distribution of the lumbar plexus was analyzed using computer images. The positions where the genitofemoral nerve emerged on the abdominal surface of the psoas major muscle were analyzed using 24 cadavers.

Results. L2/3 and above, all parts of the lumbar plexus, and nerve roots were located from the dorsal fourth of the vertebral body and dorsally. The genitofemoral nerve descends obliquely forward through the psoas major muscle, emerging on the abdominal surface between the cranial third of the L3 vertebra and the caudal third of the L4 vertebra. The safety zone of the psoas major muscle to prevent nerve injuries, excluding the genitofemoral nerve, is at L4/L5 and above.

Conclusions. The safety zone, excluding the genitofemoral nerve, is at L4-L5 and above.

From the *Department of Orthopaedic Surgery and the †Department of Anatomy, Fukushima Medical University, School of Medicine, Fukushima City, Japan.

Acknowledgement date: February 4, 2002.

First revision date: June 3, 2002.

Acceptance date: August 14, 2002.

Device status/drug statement: This report does not contain information about medical device(s)/drug(s).

Conflict of interest: No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this report.

Address reprint requests to Takatomo Moro, MD, Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima City, Fukushima 960-1295, Japan. E-mail:

© 2003 Lippincott Williams & Wilkins, Inc.