XLIF (extreme lateral interbody fusion) is a minimally invasive surgical procedure that fuses two levels of the spine using an approach from the side of the lower back. The surgery typically involves the removal of the spinal disc and placement of an interbody cage filled with bone graft in the disc space. The treated segments are then secured with fusion instrumentation, such as pedicle screws and rods.
Specifically, the abbreviation XLIF stands for:
- eXtreme, so named by the surgeons who introduced the approach
- Lateral, which means from the side of the body
- Interbody, which refers to the area between two adjacent vertebral bones in the spine
- Fusion, which refers to the process of two vertebral bones growing together
This surgery may also be referred to as Lateral Lumbar Interbody Fusion (LLIF) or Direct Lateral Interbody Fusion (DLIF).
This article describes the lower back conditions that may benefit from an XLIF surgery, the advantages and potential complications of XLIF, and the XLIF surgical procedure.
When XLIF May Be Considered
XLIF may be used to treat lower back conditions including but not limited to:
- Lumbar degenerative disc disease
- Recurrent lumbar disc herniation
- Low-grade spondylolisthesis
- Degenerative scoliosis
- Foraminal stenosis
XLIF can be performed on a single level or multiple levels.
XLIF may also be a preferred surgical technique for patients who need a revision surgery for conditions such as failed fusion, painful implants, or post-surgical complications.1 In such revision surgeries, XLIF may promote better fusion and reduce the risk of nerve injuries compared to other techniques, such as posterior lumbar interbody fusion (PLIF).1
When XLIF Is Not an Option
Anatomical challenges may sometimes make the XLIF surgery difficult to perform. These challenges include but are not limited to:
- Fusion of the lowermost segments of the spine, which are hard to access from the side. These segments may include:
- High-grade spondylolisthesis, where the position of exiting nerve roots limits access to the spinal segments3
As with any spinal fusion surgery, the patient’s underlying lower back condition is assessed through physical and diagnostic tests, and the advantages and disadvantages of surgery must be discussed in detail with the surgeon—to determine if XLIF is the surgery of choice.
Benefits of an XLIF Back Surgery
The minimally invasive approach of the XLIF procedure helps conserve more spinal tissue and minimize post-surgical discomfort. These benefits may be offered through4:
- Preserved longitudinal (length-wise) ligaments and muscles surrounding the spine
- Potential use of larger cage implants, which allows more surface area for bony fusion and better surgical outcomes
- Less blood loss
- Short duration of surgery
- Small incisions and scars
- Low risk of infection
Compared to other lumbar spine fusion techniques, XLIF also offers a relatively quick recovery time and return to normal function.
Variations of XLIF
The XLIF technique may be modified by approaching the spinal segment through different angles along the side of the spine with the intent of preserving spinal tissues and targeting the spinal problem. These variations include:
- Stand-alone XLIF, where an interbody cage is used without additional support from pedicle screws or rods. Stand-alone XLIF is typically not recommended in conditions that may cause post-surgical instability, such as facet joint arthritis, bone deformity, or when the adjacent segment is surgically fused.5 Under these conditions, a screw-rod construct is a necessary measure to help fixate the segment and support bony fusion.
- Prone single-position XLIF, where the patient lies face-down instead of on their side. Prone single-position XLIF may be considered in more complex cases, such as spinal deformity.6
- Oblique lumbar interbody fusion (OLIF), where an oblique approach is taken to preserve the psoas muscle in the front of the hip and the lumbosacral plexus (a group of nerve fibers derived from the lumbar spinal nerves).7 In addition to the L1-L5 levels of the lumbar spine, the OLIF technique also allows a surgeon to treat the lowermost L5-S1 spinal segment, which usually cannot be accessed through traditional XLIF.8
How XLIF Compares with Other Spine Fusion Surgeries
The type of spine fusion surgery typically depends on the condition being treated, overall health of the patient, skill of the surgeon, and presence of any contraindications that may rule out a specific procedure. While all types of interbody fusion surgeries serve the same purpose of fusing two spinal segments, the XLIF technique may offer a few potential advantages due to its minimally invasive approach.
XLIF vs ALIF
The XLIF technique approaches the spine through an incision made on the side of the lower back. An anterior lumbar interbody fusion (ALIF) approach is from the front, through the abdomen, and requires the organs in the abdomen and some of the major blood vessels to be moved to the side so that the surgeon can reach the spine.11
In order to minimize the risk of blood vessel and/or organ injury, a vascular surgeon or general surgeon usually performs the first part of the ALIF surgery. In an XLIF procedure, the approach from the side does not require any major organs or blood vessels to be moved.
XLIF vs PLIF
With the XLIF approach from the side, only the lateral (side) muscles are separated along their fibers and there is no cutting or tearing of the muscle. A posterior lumbar interbody fusion (PLIF) surgery approaches the spine from the back and requires some of the major muscles to be cut to access the spinal segment.
Research suggests that XLIF may restore more disc height compared to the PLIF approach.12
XLIF vs TLIF
Transforaminal lumbar interbody fusion (TLIF) approaches the spine from the back and is similar to posterior lumbar interbody fusion (PLIF), also requiring major muscles to be cut to access the spinal segment. While XLIF indirectly decompresses the nerves by restoring disc height, TLIF directly decompresses neural tissues by widening the bony openings or foramina.13
Both XLIF and TLIF are newer approaches to spinal fusion that are still being developed and studied for their advantages and drawbacks, compared to more traditional approaches.
Potential Risks and Complications of XLIF Back Surgery
The XLIF approach may give rise to potential complications, which are typically more likely to occur in patients who are obese or have ongoing health conditions, such as diabetes. The specific spinal segment being treated and the vital structures in its proximity may also contribute to the potential risks.
The primary potential complication of an XLIF surgery is failure to fuse or non-union of the joint, also called pseudoarthrosis. Pseudoarthrosis may go undetected or lead to a recurrence of pain.14 In most cases, the pain typically resolves without treatment in about 88% of these patients by the second year after surgery.10
Diabetes and smoking are possible risk factors that may explain some cases of symptomatic pseudoarthrosis that continue beyond 2 years, which may require additional surgery to relieve pain.4
Another potential complication of XLIF is damage to the spinal nerves or spinal cord. The retractor used for XLIF places pressure on the nerves running through the iliopsoas muscle in the lower spine and pelvis, leading to the potential risk of neural compromise. The damage can result in thigh pain or weakness in the thigh muscles (quadriceps).
This risk is mainly dependent on the patient’s overall build, the location of the fusion, and the surgeon’s experience in this procedure. Nerve injuries during an XLIF procedure can be reduced by intraoperative nerve monitoring, where an additional provider will track nerve signals during the surgery.15
Other possible complications associated with XLIF include but are not limited to infection, muscle weakness, pneumonia, worsening of symptoms, and accelerated degeneration at neighboring spinal levels, medically known as adjacent segment disease. As with any surgical procedure, a discussion detailing all the potential risks of the XLIF procedure should take place between the physician and the patient.