Lateral Interbody Fusion (LLIF)


Lateral lumbar interbody fusion (LLIF) is a surgical procedure to relieve pain in the lower back and legs. The procedure involves fusing adjacent vertebrae in the lower back. This helps to stabilize the spine and relieves pressure off the nerves.

Traditional posterior spine fusions involve fusing the bones of the back of the spine. During an LLIF, we access the spine from the patient’s side. The bones are then fused from the front of the spine where there is a larger surface area for fusion to occur. This procedure involves removing the disc at the affected level and replacing the disc with a spacer (or cage) that restores adequate height between the vertebrae (bones), takes the pressure off the nerves, and improves spinal alignment.

Benefits of LLIF

LLIF provides several benefits for patients suffering from lower back pain. The procedure can relieve pressure on the nerves, which can help to reduce pain in the legs and lower back. Some additional benefits include:

  • Pain relief
  • Improved posture
  • Restoration of spinal alignment and lumbar lordosis
  • Lower risk of injury to the nerves when compared to fusion surgery performed from the back of the spine
  • High rate of successful fusion

Patients who would benefit from Lateral Lumbar Interbody Fusion

LLIF is often recommended for patients who have:

  • Degenerative disc disease for levels L4/5 and above: This is a condition in which the discs between the vertebrae break down, leading to nerve compression and back pain.
  • Spinal stenosis: This is a condition in which the spinal canal narrows, putting pressure on the nerves.
  • Flat back: This is a condition in which the lumbar spine lacks appropriate lordosis (curvature)
  • Failed back surgery: This occurs when patients have had prior surgery but still experience pain. Often this pain is due to improper spinal alignment, failure of fusion, or problems at the levels above or below the previous surgery.
  • Spondylolisthesis: This condition in which one vertebra slips forward over the vertebra below it. It can be caused by aging, injury, or degenerative disc disease.
  • Recurrent herniated discs: A herniated disc occurs when the gel-like center ruptures through the outer layer. This can put pressure on the nerves and cause pain.
  • Scoliosis: This is a condition in which the spine has abnormal curvature which leads to pain.
  • Adjacent segment disease: This is a condition in which the levels above or below a previous fusion begin to break down and cause problems.

Prior to undergoing an LLIF, you should let your surgeon know if you have any of the following:

  • History of spinal infections
  • History of aortic aneurysm repair
  • History of any abdominal surgery


LLIF accesses the spine from the side of the patient. The first portion of the surgery involves getting access to the front of the spine, which is accessed via an incision on the left flank.

As the surgeon approaches the spine, neuromonitoring technology is used to ensure none of the nerves are damaged during the surgery. Once the spine is able to visualized, the LLIF is completed using the following steps:

Step 1: Removal of the disc and cartilage

The disc between the affected levels is carefully removed in its entirety. The cartilage on the top and bottom of the vertebrae is scraped off, preparing the bones for optimal fusion.

Step 2: Trials of different sized spacers

Different sizes of spacers (cages) are placed into the disc space until the correct size is determined. An x-ray machine is used during this portion of the surgery to ensure the best fit of spacer for each individual patient.

Step 3: Placing the cage

Spacers can be made of different materials, but often are a 3D printed titanium cage. Prior to placement in the patient, the cage is filled with bone graft. The cage is then carefully placed in between the vertebrae. X-rays are taken to ensure satisfactory placement of the cage.

Step 4: Incision is closed

The incision on the patient’s flank is then closed with absorbable suture and a dressing is placed.

LLIF surgery typically takes two to three hours to complete. The patient will be given general anesthesia and asleep during the surgery. After the surgery is completed, the patient will be taken to a recovery room, where they will be closely monitored. Most patients stay in the hospital for one to two days after surgery. Almost always, this surgery is paired with a posterior instrumentation and fusion, which will be discussed separately.

Risks and complications associated with Lateral Lumbar Interbody Fusion

In general, the risks associated with LLIF are rare. However, patients should be aware of all risks involved and will discuss the following prior to surgery with the surgeon:

1) Damage to Large Blood Vessels

Lateral lumbar interbody fusion is done near large blood vessels. There is a risk of damage to these vessels, leading to bleeding and blood clots. However, this complication is rare.

2) Damage to Abdominal Organs

The surgical path of lateral lumbar interbody fusion is close to the abdominal organs such as the bladder, kidneys, colon, and ureter. There is a small risk of damage to these organs.

3) Migration of the cage

In rare cases, the cage placed between the bones can move. This can lead to problems with healing and may require revision surgery. With modern technique, the risk of this is nearly eliminated.

4) Leg pain

Sometimes, the nerves can be irritated in the psoas muscle causing pain on the side of the incision. This pain is usually transient and often resolves in days to weeks.


Dallas Orthopedic Spine Surgeon
Dr Michael R Wheeler, MD
Orthopedic Spine Specialist Procedures