Patients with spinal instability or chronic back pain may require anterior or posterior lumbar spinal fusion surgery (less commonly referred to as spinal fusion with instrumentation). Spinal fusion surgery is a common treatment for such spinal disorders as spondylolisthesis, scoliosis, severe disc degeneration or spinal fractures.
What is Posterior Spinal Fusion?
Spinal fusion is the joining or fusing of two or more vertebrae; bone graft is traditionally used to facilitate fusion. This involves small amounts of bone being taken from the patient’s pelvis (autograft), or from a donor (allograft), and then packed between the vertebrae in order to “fuse” them together. This surgery is done to stabilize and strengthen the spine and to alleviate severe, chronic back pain; it is usually considered only after non-operative therapies have failed.
Specially designed implants (including cages, rods, hooks and screws) are also often used in a fusion surgery. The implants are used to ensure correct alignment between vertebrae and to help successful fusion to take place. In addition, these implants add strength and stability to the spine while healing progresses.
A fusion is not always achieved after surgery. Fusion rates vary depending on such factors such as whether or not the patient smokes, number of previous procedures, and the underlying pathology. However, there has recently been a breakthrough relating to fusions. Surgeons are now able to use bone substitutes such as bone morphogenetic proteins (BMPs) during surgery to facilitate fusion. BMP is a “substance” that causes bone growth. The use of BMP in fusion surgery is already improving fusion rates.
Posterior Lumbar Interbody Fusion (PLIF) and Anterior Lumbar Interbody Fusion (ALIF)
The two most common interbody fusion techniques used to treat chronic low back pain are PLIF and ALIF. PLIF stands for Posterior Lumbar Interbody Fusion. It is a fusion technique done from the back (posterior) of the lumbar spine and involves three basic steps:
- Pre-operative planning and templating. Before the surgery, the surgeon will use MRI and CT scans to determine what size implant(s) the patient will need.
- Preparing the disc space. An incision is made and back muscles are retracted to allow access to the vertebral disc; the surgeon then carefully removes the affected disc and surrounding tissue.
- Implants Inserted. Once the disc space is prepared, bone graft, or BMP with a cage, is inserted to promote fusion between the vertebrae. Additional implants may also be used at this time to further stabilize the spine.
ALIF, which stands for Anterior Lumbar Interbody Fusion, is similar to PLIF. However, it is done from the front (anterior) of the body. Our surgeons are leaders in this technique, and are currently involved in the development of specialized implants for use with ALIF procedures for surgeons worldwide.
More about PLIF and ALIF
For some spinal disorders your doctors will recommend spinal fusion surgery. The surgeons at our practice are highly skilled with these types of surgeries. Furthermore, the arrival of new tools such as BMPs further enhances the likelihood of a successful fusion being achieved.