Different Methods of Spinal Interbody Fusion

Spinal fusion for spondylolisthesis and other diseases has many methods and approaches. Surgeons can use the posterior approach (from the back), or they can choose to enter the spine from the front (anterior approach).

Lumbar spinal fusion has been around for 70 years, but the procedures used have evolved. Conditions treated with these procedures include spinal stenosis, spondylolisthesis, degenerative scoliosis, and spinal instability. Lumbar spinal fusion is often performed after conservative measures fail.

Oblique Lateral Lumbar Interbody Fusion (OLLIF)

OLLIF procedure represents spine surgery’s latest advancemens in minimally invasive keyhole spinal lumbar surgical technology. The OLLIF treats many of the indications that result in back pain, including Degenerative Disk Disease, Herniated Disks, spondylolisthesis , Scoliosis, and spinal stenosis.

The procedure takes less than an hour and involves an approach that goes between muscle groups and does not split/transect them. Blood loss has been shown to be 90% less than with TLIF and the procedures are outpatient!

Posterior Lumbar Interbody Fusion

The posterior lumbar fusion interbody (PLIF) approach involves entering the spine from the back. The surgeon uses pedicle screw instrumentation for this form of spinal fusion. Because 80% of the body’s stress passes through the disc space, supporting the anterior column with fusion increases the stability. This approach has the benefit over ALIF in that it only requires one incision (not two).

There are some restrictions involved with the PLIF procedure. For instance, only a limited portion of the disc space can be reached from the posterior since the dural sac ad nerve roots are in the way. In addition, limited sizes of interbody fixation devices are used, which means limited stability and fusion area.

Transforaminal Lumbar Interbody Fusion

With this procedure, the surgeon makes a small incision on the back, and exposes the lateral part of the vertebra, lamina, and facet joint. The interbody device is placed with the dura retracted. This system allows for easy viewing of the thecal sac, nerve roots, and disc space.

With the TLIF, surgery is performed much like an extended PLIF. The surgery involves expanding the disc space by removing an entire facet joint. PLIF, however, involves gaining access by removing only a portion of the joint on the side of the spine.

Anterior Lumbar Interbody Fusion

Some surgeons access the disc space through an incision in the abdomen, which is called the anterior lumbar interbody fusion (ALIF). The anterior approach affords the best exposure of the disc space and allows a large device for the fusion, which increases the surface area for fusion to set up and allows for better post-operative stability. This approach also has reduced risk for deformity caused by isthmic spondylolisthesis.

A few risks associated with the ALIF approach include:

• Great vessel injury – The aorta and vena cava lie in the front of the spine, and there is a low risk for vessel injury.
• Retrograde ejaculation – For men, there is a slight risk of ejaculation problems, but the risks is very low.
• Infection – There is a slightly higher risk for infection with ALIF, since the procedure requires an incision at the back and the abdomen.

Anterior/Posterior Lumbar Fusion

With the anterior-posterior fusion procedure, the surgeon makes an incision in the abdomen to remove the disc and place the bone graft where the material was removed, and then makes a separate incision in the back so as to affix the pedicle and bone graft. This approach involves less trauma to the muscles, but can be associated with increased blood loss.

Which Lumbar Fusion Method is Best?

All procedures have advantages and disadvantages for fusing the spine. When transforaminal lumbar interbody fusion was compared to the posterior approach, researchers found that TLIF had a decreased potential for neurological injury, preservation of posterior spinal column integrity, and improved lordotic alignment.

The authors review and compare posterior lumbar interbody fusion (PLIF) with transforaminal lumbar interbody fusion (TLIF). A review of the literature is performed wherein the history, indications for surgery, surgical procedures with their respective biomechanical advantages, potential complications, and grafting substances are presented.

Along with the technical advancements and improvements in grafting substances, the indications and use of PLIF and TLIF have increased. The rate of arthrodesis has been shown to increase given placement of bone graft along the weight-bearing axis. The fusion rate across the disc space is further enhanced with the placement of posterior pedicle screw–rod constructs and the application of an osteoinductive material.

The chief advantages of the TLIF procedure compared with the PLIF procedure included a decrease in potential neurological injury, improvement in lordotic alignment given graft placement within the anterior column, and preservation of posterior column integrity through minimizing lamina, facet, and pars dissection.

Resources

Cole CD, McCall TD, Schmidt MH, & Dailey AT (2009). Comparison of low back fusion techniques: transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion (PLIF) approaches. Curr Rev Musculoskelet Med, 2(2), 118-126.