Retroperitoneal oblique corridor to the L2–S1 intervertebral discs: an MRI study

Abstract

<jats:sec> <jats:title>OBJECT</jats:title> <jats:p>The purpose of this study was to analyze MR images of the lumbar spine and document: 1) the oblique corridor at each lumbar disc level between the psoas muscle and the great vessels, and 2) oblique access to the L5–S1 disc space. Access to the lumbar spine without disruption of the psoas muscle could translate into decreased frequency of postoperative neurological complications observed after a transpsoas approach. The authors investigated the retroperitoneal oblique corridor of L2–S1 as a means of surgical access to the intervertebral discs. This oblique approach avoids the psoas muscle and is a safe and potentially superior alternative to the lateral transpsoas approach used by many surgeons.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>One hundred thirty-three MRI studies performed between May 4, 2012, and February 27, 2013, were randomly selected from the authors’ database. Thirty-three MR images were excluded due to technical issues or altered lumbar anatomy due to previous spine surgery. The oblique corridor was defined as the distance between the left lateral border of the aorta (or iliac artery) and the anterior medial border of the psoas. The L5–S1 oblique corridor was defined transversely from the midsagittal line of the inferior endplate of L-5 to the medial border of the left common iliac vessel (axial view) and vertically to the first vascular structure that crossed midline (sagittal view).</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>The oblique corridor measurements to the L2–5 discs have the following mean distances: L2–3 = 16.04 mm, L3–4 = 14.21 mm, and L4–5 = 10.28 mm. The L5–S1 corridor mean distance was 10 mm between midline and left common iliac vessel, and 10.13 mm from the first midline vessel to the inferior endplate of L-5. The bifurcation of the aorta and confluence of the vena cava were also analyzed in this study. The aortic bifurcation was found at the L-3 vertebral body in 2% of the MR images, at the L3–4 disc in 5%, at the L-4 vertebral body in 43%, at the L4–5 disc in 11%, and at the L-5 vertebral body in 9%. The confluence of the iliac veins was found at lower levels: 45% at the L-4 level, 19.39% at the L4–5 intervertebral disc, and 34% at the L-5 vertebral body.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>An oblique corridor of access to the L2–5 discs was found in 90% of the MR images (99% access to L2–3, 100% access to L3–4, and 91% access to L4–5). Access to the L5–S1 disc was also established in 69% of the MR images analyzed. The lower the confluence of iliac veins, the less probable it was that access to the L5–S1 intervertebral disc space was observed. These findings support the use of lumbar MRI as a tool to predetermine the presence of an oblique corridor for access to the L2–S1 intervertebral disc spaces prior to lumbar spine surgery.</jats:p></jats:sec>

Stereotactic navigation for the prepsoas oblique lateral lumbar interbody fusion: technical note and case series

“…2 Even with an adequate corridor, the rate of vascular injury can be up to 10%. 8 The morphology of the sacral slope and iliac crest also needs to be evaluated to ensure that an adequate operative angle can be obtained.…”

“…The location of the aorta, vena cava, iliac arteries, and iliac veins can also be evaluated to assess the corridor between the vessels and the spine; this corridor exists in most patients. 8 It is critical to obtain 36-in standing radiographs to preoperatively evaluate not only spinal alignment, but also the position of the iliac crest on the left side to ensure that the procedure can be done (Fig. 3).…”

Evaluation of the location of intervertebral cages during oblique lateral interbody fusion surgery to achieve sagittal correction

“…Two popular and common LLIF procedures are oblique lateral interbody fusion (OLIF) and extreme lateral interbody fusion (XLIF), which each require specially designed instruments [12][13][14][15] . OLIF, especially, enables surgeons to easily and less invasively access the vacant oblique corridor in front of the psoas muscles without causing any splitting, which occurs with XLIF 16,17) . The lateral interbody fusion cage for OLIF has a lordotic angle of 6 .…”

Morphometric anatomy of the lumbar sympathetic trunk with respect to the anterolateral approach to lumbar interbody fusion: a cadaver study

“…Cadaveric investigations by Davis et al (28) and Molinares et al (29) demonstrate an adequately sized, left-sided oblique corridor at L2-L5, which could be widened via lateral decubitus positioning and the use of approach retractor systems. The prior study (28) reported left oblique corridor sizes for L2/L3, L3/L4, L4/L5 whilst the latter (29) reported measurements of these levels in addition to L1/L2 and L2/L3. Both studies were consistent in demonstrating that the larger corridors were available in the upper lumbar levels, and has been attributed to the conical morphology of the psoas muscle.…”