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.
Cervical Fusion
Many neck problems are due to degenerative changes that occur in the intervertebral discs of the cervical spine and the joints between each vertebra. Other problems are the result of injury to parts of the spine or complications of earlier surgeries. The vast majority of patients who have neck problems will not require any type of surgery. But if conservative treatments fail to control the pain, a surgeon may suggest a cervical fusion. There are two types of cervical fusion procedures three quarter anterior cervical fusion and posterior cervical fusion.
An anterior cervical fusion is performed through an incision in the front of the neck. This technique is used to:
- Remove pressure from nerve roots or the spinal cord caused by bone spurs or a herniated disc
- Stop the motion between two or more vertebrae
Removing pressure from the nerve roots or spinal cord can ease arm pain. Problems from pressure on the nerves, such as numbness or weakness in the arm or difficulty walking, may also improve. Fusion of the problem vertebrae reduces mechanical pain caused from too much motion in the spinal segment.
The posterior cervical fusion is performed through an incision in the back of the neck. This technique is used to:
- Stop the motion between two or more vertebrae
- Recreate the normal curve of the cervical spine and keep a spinal deformity from getting worse
- Stabilize the spine after a fracture or dislocation of the cervical spine
Thoracic Fusion
One of the most common surgeries for chronic back pain problems is spinal fusion surgery. It is a major surgery that is performed only when all more conservative treatment measures have failed, but it can help people suffering from chronic back pain or severe spinal deformities live normal lives again.
Now, orthopaedic spine surgeons have found a way to achieve the full benefits of spinal fusion for some patients with less bleeding, trauma, postoperative pain, time in the hospital, and healing time for the patient and reduced inpatient expenses for the health plan or insurance carrier. They are accomplishing this by applying minimally-invasive surgical techniques to spinal fusion surgery. The result is a new category of spine surgery called minimally-invasive spinal fusion surgery.
In a conventional thoracic spinal fusion procedure, surgeons must often perform a thoracotomy, or incision into the chest wall, then remove a rib to reach the spine for operative repair. The thoracotomy sometimes requires an incision up to 20 inches long. Using minimally-invasive techniques, surgeons can completely skip the thoracotomy and rib removal, instead performing their surgery through small incisions. Using a tiny, high-tech endoscopic camera, they can view the surgical site on a high-resolution TV monitor, while doing their work with long-handled instruments. Using small incisions instead of big ones offers another benefit to the patient, small scars only, and thus a better cosmetic result after surgery.
Minimally invasive surgery may not be ideal for all patients, so be sure to discuss this option with your surgeon.
Lumbar Trauma Fusion
The two least controversial reasons for a lumbar fusion are for cases that involve trauma or tumor. In both of these cases, either:
- The situation in the spine appears unstable, meaning the spine is prone to unusual movements under normal conditions which can damage tissues or cause pain or deformity, due to the underlying pathology.
- The surgery required to decompress the neural structures is deemed to render the spine unstable once this is achieved.
Fusion for degenerative disease (so called "wear and tear") is more controversial but is commonly performed. In this setting fusion can also be performed for many reasons. The most common reason to perform a fusion is for a spondylolisthesis. This is where one vertebra is slipped forward in relation to another. Not only does this throw the back out of alignment (so called "sagital balance") but it can cause pressure on nerves, particularly when they exit through their neural foramina.
A lumbar fusion is a significant operation, which requires the use of screws that are placed between the vertebrae to be fused. The bone graft is then placed around these. The screws that are used during this operation are made of titanium, and usually stay in for life.
Lumbar fusion operations involve greater risks than simple laminectomies or discectomies. Recovery is typically longer after this procedure. However, the vast number of patients undergoing this operation do well. Since these are longer operations, there is more blood loss and blood transfusion is sometimes required. Often, however, this can be blood that is autologously donated by the patient in preparation for surgery or the blood salvaged at the time of surgery. The risks, including nerve injury, hardware problems, and infection in the range of 0.5 to 15%. The risks of general complications are slightly higher than those for a simple laminectomy. Typical operating time can be anywhere from four to eight hours. Every operation is different. Most patients will spend one to two nights in ICU. Patients are given an epidural anesthetic after surgery to ensure that there is virtually no pain for the first 24 hours. A bladder catheter is usually in place. The patient will usually have a button for pain control (PCA). On the second or third day after surgery, the patient is mobilized in a lumbar brace, with the assistance of a physiotherapist. Most patients note that the first week after surgery is difficult, but by six weeks and 12 weeks after surgery most are very glad they had the surgery done.
