LLIF

LLIF, or lateral lumbar interbody fusion, is a minimally invasive spinal fusion technique that accesses the lumbar intervertebral discs from the patient's side. The commonly used approach is transpsoas, entering the psoas muscle to expose the disc space, followed by discectomy and placement of an interbody cage. Some surgeons use a retroperitoneal or oblique corridor to minimize muscle disruption. The goal is to restore disc height and achieve fusion with supplemental posterior fixation if needed.

LLIF is used to treat degenerative disc disease, spondylolisthesis, facet arthropathy, and deformity requiring one or more lumbar levels of fusion. It is most commonly performed from L1 to L4 or L5, with limited access to L5-S1 in many cases due to anatomy.

After lateral exposure, neuromonitoring helps protect neural structures. The disc is removed, endplates prepared, and an interbody cage is inserted to restore disc height and realign the spine. Indirect neural decompression may occur. Supplemental posterior pedicle screw fixation or plating is often added for stability, and stand-alone cages are used in selected patients.

Compared with posterior approaches, LLIF preserves posterior musculature and may shorten recovery, with potential for rapid rehabilitation and good restoration of sagittal balance. It avoids anterior vascular exposure but requires careful patient selection due to lateral approach risks.

Risks include injury to the lumbar plexus and femoral nerves within the psoas, leading to thigh pain, numbness, or weakness. Other possible complications are neurologic injury, vascular injury or retroperitoneal hematoma, malposition of the cage, subsidence, nonunion, dural tears, and adjacent segment disease. Not all patients are suitable, and access limitations can affect levels that can be fused.

LLIF encompasses related techniques such as direct lateral (DLIF) and extreme lateral (XLIF) interbody fusion, developed in the early 2000s, with variations in corridor and instrumentation.