Far lateral approaches (XLIF) in adult scoliosis.

Purpose: To review the literature on the use of extreme lateral interbody fusion (XLIF) in adult spinal deformity, to discuss on its limits and advantages and to propose a guide to surgical strategy.

Methods: Surgical technique XLIF is a minimally invasive surgery (MIS) technique to anteriorly access the spine from midthoracic to L5. Important aspects of the technique are a muscle splitting approach through the psoas, use of advanced neuromonitoring to detect the lumbar plexus within the psoas, bilateral annulus release and large footprint interbody cages, supported by the stronger bone of ring apophyses. Large, laterally inserted cages provide strong correction of coronally asymmetrical disc spaces. Literature review MEDLINE database, the Web using Google Scholar and proceedings of the Society for Lateral Access Surgery meetings were searched for relevant articles on technique, results and complications.

Results: XLIF with posterior percutaneous pedicle screw instrumentation provides 40-75 % correction of coronal curves, with modest increase of lordosis. Only anterior XLIF can provide less correction. Self-limited thigh symptoms are frequent after transpsoas access. Permanent neural deficit and visceral complications have also been reported. Combined XLIF-MIS could have a lower complication compared to open circumferential surgery in historical series.

Conclusions: XLIF is a promising MIS option for adult deformity. Specific surgical strategies are needed to avoid imbalance and define ideal fusion levels and methods. An XLIF-based MIS strategy with a reduced number of levels of lumbar scoliosis can lead to significant advantages. Evaluation of the incidence, complications, their avoidance and real impact on patients' outcomes is necessary to better understand the advantages of this approach. Studies comparing effectiveness and safety of traditional versus XLIF approaches are needed to assist evidence-based decision making.