Definition of spinal fusion
Spinal fusion is surgery to permanently connect two or more vertebrae in your spine, eliminating motion between them.
Spinal fusion involves techniques designed to mimic the normal healing process of broken bones. During spinal fusion, your surgeon places bone or a bone-like material within the space between two spinal vertebrae. Metal plates, screws and rods may be used to hold the vertebrae together, so they can heal into one solid unit.
Because spinal fusion surgery immobilizes parts of your spine, it changes the way your spine can move. This places additional stress and strain on the vertebrae above and below the fused portion, and may increase the rate at which those areas of your spine degenerate.
Why it’s done
Spinal fusion permanently connects two or more vertebrae in your spine to improve stability, correct a deformity or reduce pain. Your doctor may recommend spinal fusion to treat the following spine problems:
- Broken vertebrae. Not all broken vertebrae require spinal fusion. Many heal without treatment. But if a broken vertebra makes your spinal column unstable, spinal fusion surgery may be necessary.
- Deformities of the spine. Spinal fusion can help correct spinal deformities, such as a sideways curvature of the spine (scoliosis) or abnormal rounding of the upper spine (kyphosis).
- Spinal weakness or instability. Your spine may become unstable if there’s abnormal or excessive motion between two vertebrae. This is a common side effect of severe arthritis in the spine. Spinal fusion can be used to restore spinal stability in such cases.
- Spondylolisthesis. In this spinal disorder, one vertebra slips forward and onto the vertebra below it. Spinal fusion may be needed to treat spondylolisthesis if the condition causes severe back pain or nerve crowding that produces leg pain or numbness.
- Herniated disk. Spinal fusion may be used to stabilize the spine following removal of a damaged (herniated) disk.
- Chronic low back pain. Spinal fusion may be used to restrict spinal motion in an effort to relieve chronic low back pain that cannot be attributed to a specific disorder. This use of spinal fusion is controversial, however, as research has shown inconsistent results regarding the effectiveness of spinal fusion in treating nonspecific low back pain.
Risks of spinal fusion
Spinal fusion is generally a safe procedure. But as with any surgery, spinal fusion carries the potential risk of complications.
Potential complications include:
- Poor wound healing
- Blood clots
- Injury to blood vessels or nerves in and around the spine
- Pain at the site from which the bone graft is taken
Beyond the immediate risks of the procedure, spinal fusion surgery changes how your spine works by shifting stress from the fused vertebrae to adjacent areas of your spine. This added stress may accelerate the process of wear and tear in the vertebral joints on either side of the fusion, causing further damage and possibly chronic pain.
How you prepare for spinal fusion
Preparation before surgery may involve trimming hair over the surgical site and cleaning the area with a special soap or antiseptic. Your doctor will give you specific instructions. Tell your doctor about any medications you are taking. You may be asked not to take some medications before the surgery.
What you can expect
During spinal fusion
Surgeons perform spinal fusion with a general anesthetic, so you’re unconscious during the procedure. Surgeons have developed a variety of techniques for performing spinal fusion surgery. The technique your surgeon uses depends on the location of the vertebrae to be fused and the reason for the spinal fusion.
Generally, the procedure involves the following:
- Incision. To gain access to the vertebrae being fused, the surgeon makes an incision in one of three locations: in your back directly over your spine, on either side of your spine, or in your abdomen or throat so that your surgeon can access the spine from the front. The muscles and blood vessels then are moved away from the spine as much as possible to allow the surgeon to clearly see your spine.
- Bone graft preparation. The bone grafts that actually fuse two vertebrae together may come from a bone bank or from your own body, usually from your pelvis. If your own bone is used, the surgeon makes an incision above your pelvic bone, removes a small portion of it, and then closes the incision.
- Fusion. To fuse the vertebrae together permanently, the surgeon places the bone graft material between the vertebrae. Metal plates, screws or rods may be used to help hold the vertebrae together while the bone graft heals.
In selected cases, some surgeons use bone morphogenetic proteins (BMPs) instead of bone grafts. BMPs are synthetic substances that help promote bone growth and speed the fusion of the vertebrae. This makes it easier for surgeons to perform spinal fusion through several smaller incisions, rather than through one larger incision.
After spinal fusion
A hospital stay of two to three days is usually required following spinal fusion. Depending on the location and extent of your surgery, you may experience some pain and discomfort but the pain can usually be well controlled with medications.
After you go home, contact your doctor if you exhibit signs of infection, such as:
- Redness, tenderness or swelling
- Wound drainage
- Shaking chills
- Fever higher than 100 F (38 C)
It may take several months for the affected bones in your spine to heal and fuse together. Your doctor may recommend that you wear a brace for a time to keep your spine aligned correctly. Physical rehabilitation can teach you how to move, sit, stand and walk in a manner that keeps your spine properly aligned.
Results of spinal fusion
Spinal fusion is typically an effective treatment for fractures, deformities or instability in the spine. But study results are more mixed when the cause of the back or neck pain is unclear. In many cases, spinal fusion is no more effective than nonsurgical treatments for nonspecific back pain.
It can be difficult to be certain about what exactly is causing your back pain, even if a herniated disk or bone spurs show up on your X-rays. Many people have X-ray evidence of back problems that have never caused them any pain. So your pain might not be associated with whatever problem has been revealed on your imaging scans.
Even when spinal fusion provides symptom relief, it can eventually result in more back pain in the future. Immobilizing a section of your spine places additional stress and strain on the areas around the fused portion. This may increase the rate at which those areas of your spine degenerate — so you may need additional spinal surgery in the future.