A lumbar fusion is when two or more vertebrae in the low back are “fused” together to create a solid bridge of bone between the two vertebrae and across the disk space. A fusion is usually performed to eliminate movement between vertebrae and stabilize a painful or unstable segment of the spine. Once a segment of the spine is stabilized the patient usually experiences some relief of pain. Surgery is not recommended unless there is almost a 70% chance of improving your level of pain. This approximately 70% chance of improvement does not necessarily mean that you will be completely pain free but rather that your level of pain should be significantly improved.

There are may ways to perform a fusion. They are named according to the location the bone graft is placed.

Posterior Fusion: the bone is placed on the back side of the vertebra from an incision on your back. Screw and rods or plates are often uses to stabilize your spine and speed the rate of healing of the fusion.

Interbody Fusion: the bone is placed between the vertebra. This allow the strongest, most predictable, and most reliable fusion in the low back. This places the bone graft in line with the forces on the spine and aids in healing. Interbody fusions can be performed from the front (Anterior Interbody Fusion), or from the back (Posterior Interbody Fusion). An Anterior Interbody Fusion procedure is performed via an incision in a patient’s abdomen. The vertebral bodies are approached from the front and a femoral ring (cadaver bone), or cylindrical cage is placed between the two vertebral bodies. The femoral ring or cage instrumentation is filled with bone graft usually obtained from the patient’s hip (iliac crest), or BMP. If fusion is successful, motion between the vertebrae will stop and any pain caused by abnormal motion between those vertebrae will no longer exist.

Posterior Interbody Fusion sometimes called a posterolateral spinal fusion, is performed from an incision made in the back. The procedure entails roughening the surfaces of the transverse processes and inserting bone graft between the transverse processes. The bone is usually obtained from a patient’s hip (iliac crest), or BMP may be used. If fusion is successful, motion between the vertebrae will stop and any pain caused by abnormal motion between those vertebrae will no longer exist.

The decision on the approach is a complicated decision made by your surgeon based on the individual patients particular problem, anatomy and the skill and experience of your surgeon. Interbody fusions are done with bone graft as well as cages made from titanium, bone, carbon fiber or plastic. Often it is also best to use screws and rods in the back of the spine to improve the success rate.