The anatomical relationship of the diaphragm to the thoracolumbar junction during the minimally invasive lateral extracoelomic (retropleural/retroperitoneal) approach.

OBJECT The thoracolumbar junction (T11-L2) poses an anatomical dilemma, given the presence of the lower rib cage and the diaphragm when performing anterolateral approaches. To circumvent dealing with the diaphragm, a minimally invasive lateral extracoelomic approach has been used to approach the thoracolumbar junction by mobilizing the diaphragm anteriorly. No anatomical studies have described the attachments of the diaphragm and their surgical significance during the lateral approach to the thoracolumbar spine. The objective of this study is to describe the anatomical relationship of the diaphragm in reference to the minimally invasive lateral approach to the thoracolumbar spine and its surgical significance. METHODS Nine adult fresh-frozen cadaveric specimens were dissected and studied (18 sides). All specimens were placed in the lateral decubitus position, similar to the surgical technique, for the dissections. The relationship between the retroperitoneum, retropleural space, diaphragm, and thoracolumbar spine was analyzed in reference to the minimally invasive lateral approach. Special attention was given to the attachments of the diaphragm and their relationship to the ribs during the early stages of the approach. RESULTS All 18 sides were successfully dissected, analyzed, and photographed. The diaphragm is a musculotendinous sheet extending between the thoracic and abdominal cavities. Its attachments can be divided into 3 main categories: 1) sternal or anterior, 2) costal or lateral, and 3) lumbar or posterior. These attachments are described in detail, with specific reference to the lateral approach. When performing the minimally invasive lateral extracoelomic approach to the thoracolumbar spine, the lateral and posterior attachments must be identified and dissected to successfully mobilize the diaphragm anteriorly. CONCLUSIONS The diaphragm has multiple attachments that can be categorized as anterior, lateral, and posterior. In reference to the minimally invasive lateral extracoelomic approach to the thoracolumbar junction, the surgically significant attachments are primarily to the 12th rib and transverse process of L-1.