What is it about?

Oblique lumbar interbody fusion is a mini-open retroperitoneal approach that uses a wide corridor between the left psoas muscle and the aorta above L5. This approach avoids the limitations of lateral lumbar interbody fusion, is considered less invasive than anterior lumbar interbody fusion, and is similarly effective for indirect decompression and improving lordosis while maintaining a low complication profile. Including L5-S1, when required, adds to these advantages, as this allows single-position surgery. However, variations in vascular anatomy can affect the ease of access to the L5-S1 disc. The nuances of three different oblique anterolateral techniques to access L5-S1 for interbody fusion, namely, left-sided intra-bifurcation, left-sided pre-psoas, and right-sided pre-psoas approaches, are illustrated using three representative case studies.

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Why is it important?

Oblique access to L5-S1 is not as straightforward as that for levels above L5. Variations in vascular anatomy create unique situations for which approaches may need to be customized. Oblique anterolateral approaches to L5-S1 have been described in previous studies as staying lateral to, or approaching between the bifurcated common iliac vessels. These variations of technique have been found to be safe and feasible in individual studies. However, these studies have not provided adequate guidance regarding the choice of approach. Careful assessment of the vascular anatomy is critical as vascular injuries range from 0.3%-4.3%, especially when L5-S1 is included. Three representative case studies are presented to describe how the three previously described variations of approaches can be potentially customized based on a patient’s anatomy.

Perspectives

Most patients could possibly undergo L5-S1 OLIF through more than one of the approaches described above. The choice should depend on the access surgeon’s comfort level and experience. However, the anatomic relationship of the left CIV to the L5-S1 disc may also be an important consideration. A wide anterior interval between the left and right CIVs, and a more lateral position of the left CIV (Case 1) may favor an intra-bifurcation approach. If the medial border of the left CIV is medial to the facet line without a distinct fat plane underneath, the intra-bifurcation approach may be challenging, and a pre-psoas approach may be considered (Cases 2, 3). In such cases, I personally prefer a right-sided pre-psoas approach for the following reasons. The right CIV is somewhat vertical and is visible throughout its course in a right-sided approach, while the left CIV takes a more horizontal oblique course and is often hidden underneath its accompanying artery in left-sided approaches. In my experience, the more vertical right CIV is far more predictable in its course and easier to retract medially due to its rounded lateral edge, unlike the oblique and flat left CIV.

Dr Chirag A Berry
University of Cincinnati

Read the Original

This page is a summary of: Nuances of oblique lumbar interbody fusion at L5-S1: Three case reports, World Journal of Orthopedics, June 2021, Baishideng Publishing Group Co., Limited (formerly WJG Press),
DOI: 10.5312/wjo.v12.i6.445.
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