A fusion is a surgical technique in which one or more of the vertebrae of the spine are united together (“fused”) so that motion no longer occurs between them. The concept of fusion is similar to that of welding in industry.
Spinal fusion surgery, however, does not weld the vertebrae during surgery. Rather, bone grafts are placed around the spine during surgery. The body then heals the grafts over several months – similar to healing a fracture – which joins, or “welds,” the vertebrae together.
Spine surgery is usually recommended only when your doctor can pinpoint the source of your pain. To do this, your doctor may use imaging tests, such as x-rays, computed tomography (CT), and magnetic resonance imaging (MRI) scans.
Spinal fusion may relieve symptoms of many back conditions, including:
- Degenerative disc disease
- Spinal stenosis
Spinal fusion eliminates motion between vertebrae. It also prevents the stretching of nerves and surrounding ligaments and muscles. It is an option when motion is the source of pain, such as movement that occurs in a part of the spine that is arthritic. The theory is if the painful vertebrae do not move, they should not hurt.
If you have leg pain in addition to back pain, your surgeon may also perform a decompression (laminectomy). This procedure involves removing bone and diseased tissues that can put pressure on spinal nerves.
Fusion will take away some spinal flexibility, but most spinal fusions involve only small segments of the spine and do not limit motion very much.
Lumbar spinal fusion has been performed for decades. There are several different techniques that may be used to fuse the spine. There are also different “approaches” your surgeon can take for your procedure.
Anterior Lumbar Fusion
Your surgeon may approach your spine from the front. This is an anterior approach and requires an incision in the lower abdomen.
Posterior/Lateral Lumbar Fusion
A posterior approach is done from your back. Or your surgeon may approach your spine from the side, called a lateral approach.
Minimally invasive techniques have also been developed. These allow fusions to be performed with smaller incisions.
The right procedure for you will depend on the nature and location of your disease.
All spinal fusions use some type of bone material, called a bone graft, to help promote the fusion. Generally, small pieces of bone are placed into the space between the vertebrae to be fused.
A bone graft is primarily used to stimulate bone healing. It increases bone production and helps the vertebrae heal together into a solid bone. Sometimes larger, solid pieces are used to provide immediate structural support to the vertebrae.
In the past, a bone graft harvested from the patient’s hip was the only option for fusing the vertebrae. This type of graft is called an autograft. Harvesting a bone graft requires an additional incision during the operation. It lengthens surgery and can cause increased pain after the operation.
Most autografts are harvested from the iliac crest of the hip.
One alternative to harvesting a bone graft is an allograft, which is cadaver bone. An allograft is typically acquired through a bone bank.
Today, several artificial bone graft materials have also been developed.
Your surgeon will discuss with you the type of bone graft material that will work best for your condition and procedure.
After bone grafting, the vertebrae need to be held together to help the fusion progress. Your surgeon may suggest that you wear a brace.
In many cases, surgeons will use plates, screws, and rods to help hold the spine still. This is called internal fixation, and may increase the rate of successful healing.
With the added stability from internal fixation, most patients are able to move earlier after surgery.