Lumbar Interbody Fusion
Lumbar interbody fusion involves complete discectomy and inserting a cage with bone graft between two vertebral bodies. A fusion done in the interbody area has most favorable chance to succeed due to wider surface area and ability to accommodate large amount of graft.
Types of Lumbar Interbody Fusion:
- Posterior Lumbar Interbody Fusion (PLIF): A posterior approach is used to access interbody area. Space between spinal cord and facet joint is used to enter disc and do interbody job. This is traditional method of lumbar interbody fusion.
- Trans-Foraminal Lumbar Interbody Fusion (TLIF): A posterior approach is used similar to PLIF; however, interbody area is accessed by resecting the bone lateral to spinal cord. This avoids excessive retraction of spinal cord to avoid nerve irritation. TLIF is especially useful in revision surgeries to avoid scar tissue around spinal cord from previous surgery. This approach is also used for minimally invasive lumbar interbody fusion (MIS TLIF).
- Anterior lumbar Interbody Fusion (ALIF): Lumbar intervertebral disc is accessed from an anterior (trans-abdominal) approach. Advantage of this procedure is that a very big cage can be inserted. A bigger cage supports lumbar vertebrae better and allow more bone graft insertion for fusion.
- Lateral/ Extreme Lateral Lumbar Interbody Fusion (LLIF/ XLIF): Interbody area is accessed by a lateral approach. A cage is inserted in left-right direction spanning the entire width of the disc space. LLIF provides robust support to lumbar vertebrae and accommodates large quantity of graft for fusion. LLIF can be done in a minimally invasive way. They are commonly used for correction of adult degenerative scoliosis deformities.
- Oblique Lumbar Interbody Fusion (OLIF): OLIF is similar to LLIF other than that disc is entered slightly anteriorly. This prevents psoas muscle disruption, which is a common cause of thigh soreness after LLIF surgery.
Occasionally, lumbar spine is fused without interbody cage/ grafting. This is called posterolateral Lumbar fusion (PLF) wherein fusion is attempted at facet joint or nearby outer aspect of vertebra. All fusion techniques have one common purpose, achieving union between two vertebral bodies. These approaches are used in different situation as per the unique requirement of the case and surgeon’s preference.
One lumbar fusion technique deserves special mention:
- MIS TLIF (Minimally Invasive Trans-Foraminal Lumbar Interbody Fusion): MIS TLIF is most commonly performed lumbar fusion surgery. It combines concepts of minimally invasive lumbar decompression and minimally invasive lumbar fusion surgery. Specialized tubular or expandable retractors are used to perform lumbar decompression and interbody fusion (TLIF), using cage spacer and bone graft. Pedicle screws are then placed 1) through expandable retractors, 2) percutaneously using fluoroscopy, 3) using computer navigation/ robotics.