What is a Spinal Fusion?
Spinal fusion is a process in which pieces of bone, screws and rods are used to connect two vertebra together. When used for spinal stenosis treatment it is designed to stop painful motion between vertebrae. There are many different techniques and approaches to this surgery, but they all involve a bone graft between two or more vertabrae, and sometimes, extra supplimentary hardware like screws and cages.
The bone for the graft comes from the patient (autograph), or a "bone bank" (allograph). The bone in autograph's tend to heal better, but allograph's alleviate the need for an extra incision in the patient to obtain a piece of bone. An allograph is associated with less pain while the autograph is more reliable and predictable. Currently there is research into synthetic bone subsitutes that seem to be promising.46
Once the bone graft is inserted, it provokes a biological response that makes the vertebrae and the bone graft fuse into one long bone. This increases the stability of the segment of the spine and eliminates the motion between the two vertebrae that was causing pain.
A spinal fusion can be performed on many different "levels". This refers to how many vertebra are fused together. A one-level fusion fuses two vertebra and one disc together. A two-level fusion fuses three vertebra and two disks together. A three-level fusion fuses four vertebra and three discs together.
The operation can be performed in several different ways. The surgery can be done from the back (posterior), from the the front (anterior), or in some cases, both. The surgeon decides which approach is best based on tests and examinations done prior to surgery based on the patient's unique condition.
Spinal Fusion Indications
A spinal fusion is used when abnormal or excessive motion in a segment of the spine is creating pain. Some of the conditions that commonly create pain that fusion could be helpful for are:
- Cervical disk herniations
- Spondylolisthesis (slipped vertebrae)
- Scoliosis (S shaped spine)
- Fractured vertebra
- Lumbar deformity
- Instability
A patient could have one of these conditions concurrently with spinal stenosis. That is when a spinal fusion is coupled with a decompressive surgery such as a laminectomy or laminotomy.
Spinal Fusion Risks
As with any other surgery, there are possibilities for complications but these tend to occur less then one percent of the time. The complications that do arise are the same type as in other surgeries, such as:
- Infection
- Bleeding
- Anesthetic problems
- Urinary difficulties
- Absent or decreased intestinal function
There is also a five to ten percent chance that fusion will not occur. This is more likely in people who either: smoke, are obese, or have undergone radiation therapy for cancer. Also, in twenty percent of the surgeries, the lower back pain symptoms continue to occur. This becomes more likely the greater the number of vertebra fused. If too many vertebra are fused then this could create more pain from inflexibility then originally was present before the operation.
Spinal Fusion Success Rate
There have been several studies on the success rate of spinal fusion, and they all give general success rates above ninety percent.46,47,48 This means that ninety percent of the time successful fusion is obtained. However, even when fusion is successful, there is rarely a one hundred percent cure to all pain and discomfort. Patients can expect a long term solution to most if not all of their back pain problems. It is not a quick fix.
The healing process after the operation is prolonged. It takes weeks to recover from the pain of the surgery, and then months, maybe even a year, to regain mobility and abilities the patient had before the surgery. A well maintaned physical rehabilitation schedule and good nutrition, as recommended by a physician, greatly increase the results and time it take to obtain them.
Spinal fusion does create more support and stability in the spine, but does not allow for natural movement between the two vertebrae after the prodedure. This also puts more stress on the vertebra below and above the fusion.
Last Updated: 03/17/2011