Anatomy of the Lateral Lumbar Approach: Studies of the Psoas Muscle and Lumbar Plexus

Dakwar E, Uribe JS The minimally invasive lateral retroperitoneal transpsoas approach for lumbar interbody fusion (extreme lateral interbody fusion [XLIF®, NuVasive®, Inc., San Diego, CA]) is used to treat common spinal disorders, including degenerative disc disease, spondylolisthesis, traumatic injuries, and spinal deformity.1-4 The XLIF approach provides anterior column access to the disc space from L1 to L5 without the need for an access surgeon. Access is achieved using a 90 degree off-midline surgical pathway passing through the retroperitoneal cavity and traversing the psoas muscle, while preventing injury to the nerves of the lumbar plexus. A thorough understanding of the anatomic complexity of the lumbar plexus and psoas muscle is essential for performing the procedure safely. The anatomy of the psoas muscle and lumbar plexus has been well described in previous surgical, anatomic, cadaveric, and radiographic studies.5-17 The objective of this chapter is to review the relevant anatomy of the psoas muscle and lumbar plexus with respect to the XLIF approach and summarize the pertinent studies in the literature. Muscular anatoMy