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What Is Lateral Lumbar Interbody Fusion?

Lateral lumbar interbody fusion is spinal fusion surgery that reaches a lumbar disc space through the patient's side rather than through the abdomen or directly through the back. It is commonly abbreviated LLIF. Depending on the specific technique, the surgical corridor can pass through the psoas muscle or in front of it within the retroperitoneal space. The damaged disc is removed and replaced with a large interbody cage containing bone-graft material to restore disc height, alignment, and stability while fusion develops.

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What Is Lateral Lumbar Interbody Fusion?

Lateral lumbar interbody fusion is spinal fusion surgery that reaches a lumbar disc space through the patient's side rather than through the abdomen or directly through the back. It is commonly abbreviated LLIF. Depending on the specific technique, the surgical corridor can pass through the psoas muscle or in front of it within the retroperitoneal space. The damaged disc is removed and replaced with a large interbody cage containing bone-graft material to restore disc height, alignment, and stability while fusion develops.

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Why Is Lateral Lumbar Interbody Fusion Performed?

LLIF is used for selected patients with degenerative disc disease, spinal stenosis, spondylolisthesis, adult spinal deformity, or instability that requires interbody fusion. The lateral approach can restore disc and foraminal height and can provide indirect decompression by tensioning ligaments and enlarging the space available for nerves. It can also be useful for multilevel deformity correction because large cages can be placed across the disc spaces through relatively small incisions. Patient selection depends on the spinal level, vascular and psoas anatomy, nerve compression, bone quality, alignment goals, and whether direct posterior decompression is also needed.

How Is Lateral Lumbar Interbody Fusion Performed?

The patient is positioned on the side or, with some modern techniques, prone while the surgeon identifies the target level with imaging. A retroperitoneal corridor is developed to the lateral aspect of the lumbar spine, and the psoas muscle is either traversed or mobilized according to the chosen approach. The disc is removed, the vertebral endplates are prepared, and a wide interbody cage with bone graft is inserted across the disc space. Supplemental screws, rods, or lateral fixation can be added when the fusion requires additional stability.

What Is Recovery Like After Lateral Lumbar Interbody Fusion?

Patients usually begin walking soon after surgery as pain and neurologic status allow. Temporary thigh pain, numbness, or hip-flexor weakness can occur after transpsoas techniques because the surgical corridor passes near the lumbar plexus. Bending, twisting, heavy lifting, and high-impact exercise are restricted while the fusion begins to heal. Follow-up imaging is used over the following months to monitor cage position, alignment, hardware, and development of solid bone fusion.

What Are the Risks and Complications?

Possible complications include infection, bleeding, cage subsidence, malposition, pseudarthrosis, persistent pain, and failure of indirect decompression. Transpsoas approaches can injure or irritate the lumbar plexus and cause thigh numbness, hip-flexor weakness, or more persistent motor deficits. Vascular, bowel, ureteral, or sympathetic-nerve injuries are less common but can be serious. Some patients later require posterior decompression, hardware revision, or another fusion procedure when symptoms or instability persist.

Frequently Asked Questions About Lateral Lumbar Interbody Fusion

Is LLIF the same as XLIF?

XLIF is one branded form of lateral transpsoas interbody fusion. LLIF is a broader term that includes several lateral approaches to the lumbar disc space.

Can LLIF indirectly decompress nerves?

Yes. Restoring disc height can enlarge the neural foramina and tension surrounding ligaments, which can reduce nerve compression without directly removing bone around the nerve in selected patients.

Why can thigh symptoms occur after LLIF?

Transpsoas approaches pass close to the lumbar plexus, so temporary irritation of sensory or motor nerves can cause thigh pain, numbness, or hip-flexor weakness.

Can LLIF be used at L5-S1?

Standard lateral access to L5-S1 is often limited by the iliac crest and major blood vessels, so another interbody approach is commonly chosen for that level.

References

Lateral Lumbar Interbody Fusion: Indications, Outcomes, and Complications. PubMed. https://pubmed.ncbi.nlm.nih.gov/26803545/. Date Accessed September 11, 2026.

Lateral Lumbar Interbody Fusion-Outcomes and Complications. PubMed. https://pubmed.ncbi.nlm.nih.gov/29038952/. Date Accessed September 11, 2026.

Lateral lumbar interbody fusion: a systematic review of complication rates. PubMed. https://pubmed.ncbi.nlm.nih.gov/28456671/. Date Accessed September 11, 2026.

Lateral Lumbar Interbody Fusion: What Is the Evidence of Indirect Neural Decompression? A Systematic Review of the Literature. PubMed. https://pubmed.ncbi.nlm.nih.gov/32523482/. Date Accessed September 11, 2026.

Single Position Prone Lateral Lumbar Interbody Fusion: A Review of the Current Literature. PubMed. https://pubmed.ncbi.nlm.nih.gov/39090374/. Date Accessed September 11, 2026.