Spinal fusion is indicated for the treatment of a large variety of spine problems. A common reason to perform spinal fusion is disc-related back pain, often referred to as degenerative disc disease. It can also be performed to treat painful arthritis of the facet joints (the small paired joints which sit behind each disc and contribute to motion), as well as back pain associated with instability of the spine (such as spondylolisthesis) and progressive deformity of the spine (such as scoliosis or ankylosing spondylitis).
How are Spinal Fusion Operations Done?
Spinal fusion is a type of surgery that includes many different specific surgical techniques and options, each with their unique potential risks and benefits. These include:
- Operating on the front of the spine (anterior), the back (posterior), or both (anterior/posterior, circumferential, or '360'), are all potential surgical options.
- Use of the patient’s own bone for bone grafting (“autograft”), a bank (cadaver) bone, or bone forming molecules (bone morphogenetic proteins, or BMPs) are also options to help create the bone fusion, as is the potential use of metal rods and screws (internal fixation) to aid in the healing of the fusion and minimize or eliminate the need for postoperative external bracing.
A complete discussion of the types of techniques for spinal fusion and the reasons to perform one technique over another is beyond the scope of this article. Patients should be sure to become educated about and have a thorough discussion regarding surgical options with their doctor if spinal fusion is recommended as an option to treat low back pain.
Does Spinal Fusion Limit Mobility?
As one of the goals of spinal fusion is to stop painful motion of the disc or facet joints, this procedure stiffens the affected segment of the spine as a matter of necessity. However, if the motion of the low back is severely limited due to pain preoperatively, overall clinical motion following fusion can be similar or even better than before surgery if the pain is successfully relieved. Even if the motion seems the same or greater after surgery, the motion at the fused disc(s) is (are) always severely limited, and the motion seen clinically is made up of increased motion from surrounding discs and/or the hip joint. This is less of an issue for the L5-S1 segment if it is fused, as this segment has less motion to begin with.
Does Healing of the Fusion Guarantee Relief of Pain?
Successful bone healing of the fusion is generally needed for long term pain relief, but unfortunately successful bone healing does not guarantee pain relief.
Fusion rates of 60 to 95% have been reported depending on the fusion technique used and the surgeon's experience and skill, but clinical success in term of satisfactory improvement in preoperative pain occurs in only 50-80% of patients. It is thought that this is due at least in part because of diagnostic challenges, so that even if there is a successful fusion, if the patient’s pain was not caused by motion at that disc space, the patient will still have pain after surgery. When a patient continues to have pain despite fusion surgery, this is generally referred to as failed back surgery syndrome.
