Anatomy of the Lateral Approach at the Thoracolumbar Junction

Dakwar E, Uribe JS The thoracolumbar junction, encompassing the eleventh thoracic to the second lumbar vertebrae (T11-L2), is a common location for traumatic and nontraumatic pathologies because of the relative rigidity of the thoracic spine (afforded by the ribs and their sternal attachments) superiorly and the mobility of the lumbar region inferiorly.1-3 Lateral approaches to this junctional area have been described as early as 1925.4-7 The thoracolumbar junction poses anatomically unique challenges to the spine surgeon during lateral approach procedures, given access challenges introduced by the lower border of the rib cage and the diaphragm. Multiple surgical approaches have been described to access this area, from conventional open to less-invasive exposures, as well as coelomic and extracoelomic approaches. Extracoelomic approaches include both the retropleural and retroperitoneal access corridors, whereas coelomic exposures include transthoracic and transperitoneal approaches.8-13 The minimally invasive lateral extracoelomic approach to the thoracolumbar spine has been previously described.8,14 During the minimally invasive extracoelomic approach, the diaphragm must be mobilized to communicate the thoracic and abdominal cavities at the thoracolumbar junction. An understanding of the anatomy of the diaphragm and its relationship to nearby structures is critical to a successful approach and recovery. In this chapter, we describe the anatomic relationship between the retroperitoneal space, retropleural space, diaphragm, and thoracolumbar spine in reference to the minimally invasive extreme lateral interbody fusion (XLIF®, NuVasive®, Inc., San Diego, CA) approach.