What Should I Know about Lumbar Spinal Fusion?
Most low back pain can be effectively managed with a variety of helpful interventions. Physical therapy, weight loss, smoking cessation, chiropractic treatment, steroid injections, and traction are just a few examples of conventional treatment that may improve back pain.
In select circumstances in which these treatments fail, a physician may discuss with you that your best long-term outcome could be achieved with a lumbar fusion. There are several important aspects of lumbar fusion surgery to understand:
- In what circumstances might a fusion be recommended?
- How does a fusion actually improve your pain?
- How does a surgeon perform a lumbar fusion?
In what circumstances might a fusion be recommended?
A physician may recommend a lumbar fusion in circumstances where the predominant source of back pain is thought to be a severely degenerated disc between two vertebral bones or to a "slippage" of the spine bones (which is referred to as "spondylolisthesis"). Slippage of the bones results in misalignment of the spine and possible entrapment of the spinal nerves.
Other circumstances exist in which a fusion may best treat the source of back and leg pain. A lumbar fusion may be recommended for diagnoses such as a recurrent disc herniation, scoliosis or curvature of the spine, or for a traumatic injury of the spine such as a fracture. All of these different conditions can cause back and leg pain.
How does a fusion actually improve your pain?
It is believed that pain originates in levels of the spine where the bones are slipped or the discs or joints are damaged. This may be due to irritated nerve endings around the disc, bone, or joints themselves, or it may be due to actual entrapment of the spinal nerves in that region. By eliminating motion across the damaged level, pain can be improved. A solid bridge of bone—a fusion—eliminates motion that normally would take place at the disc space and in the joints of the spine.
When referring to what discs are involved, a physician will refer in medical jargon to the "levels involved." A one-level fusion links or fuses together two vertebral bones on either side of a diseased disc. A two-level fusion links or fuses together three vertebral bones with two intervening discs. A fusion is an actual bridge of solid bone that is created by surgery and links the bones together to maintain alignment and provide stability and strength.
How does a surgeon perform a lumbar fusion?
A lumbar fusion can be achieved in a variety of ways and through several different approaches to the spine. What that means for you is that an incision may be made on your abdominal wall, your flank, your backside, or a combination of these approaches. "Anterior" means "from the front" and "posterior" means from your backside. A surgeon will study your x-ray studies and determine whether you will require one approach or the other (or, in less common circumstances, both). Though you may know many people who have had a fusion, keep in mind that many options are possible and your surgeon will select the approach and technique that is best tailored for your spine.
He/she will also decide whether titanium metal screws would be beneficial. These are typically placed through the "pedicle" bone of the spine and thereby allow purchase of the back, middle, and front parts of your vertebral bones. These screws are attached to a rod or plate that is contoured to your spine. This type of spinal "instrumentation" provides immediate strength to your spine during the process of bone fusion.
In other situations, a titanium metal "cage" or bone cylinder may be screwed into your disc space. This is called an interbody fusion because it is between the "bodies" of the vertebral bones and is across the diseased disc space. This can be done from the front (anterior) or from the backside (posterior). An approach through the abdomen (anterior) may be done "laparoscopically" with several small incisions or "open" through a single incision. Your surgeon can discuss the advantages and disadvantages of both techniques as well as what has worked best in their own surgical experience.
Typically, these bone or metal "cages" or cylinders are packed with bone graft taken from either your pelvis (ileum) or tailbone (spinous processes and laminar bone). Bone graft serves as the source of bone cells to help initiate the fusion process at the surgery site. In some circumstances, cages may be used in conjunction with pedicle screws.
Other techniques involve placement of bone marrow or "graft" along the sides of your spine (with or without screws). This is called a "posterolateral" lumbar fusion and is another effective way to fuse a level of the lumbar spine. The source of the bone graft material in your pelvis (ileum) can remain painful for weeks or months following surgery but gets better in the majority of patients.
Lumbar Spinal Fusion Surgery: Risks and Recovery
The risks of lumbar spinal fusion surgery are similar to other spine operations and should be discussed at length with your surgeon.
Following surgery, you may be asked to wear a plastic brace or cloth corset for a period of time (weeks or months). Some surgeons do not use braces at all, and what your surgeon recommends will likely be based on what they have found to be most successful in their own practice.
The process of healing a fusion can take many months or well over a year to be complete. For these reasons, it is important to realize before surgery that positive results will be slow to realize and patience following your surgery will be necessary. A fusion is not a quick fix; rather, it is a commitment of patient and surgeon to a long process of improving your back and leg pain. Total or 100% cures are rare. Realistically, patients can expect a dramatic and lasting improvement in their back and leg pain. Though many patients are worried about a lumbar fusion taking away their ability to bend and twist, the majority of patients eventually regain the ability to bend in all directions. This mobility can allow for a return to work and many enjoyable recreational activities.
The success rates of lumbar fusion can be lower in patients who smoke, are overweight, have diabetes or other significant medical illnesses, have osteoporosis, or who have had radiation treatments that included the lower back. Good nutrition and slowly increasing activity (as recommended by your physician) in the recovery period can help achieve success.
In the future, lumbar disc or joint replacement may be an answer to the debilitating back and leg pain associated with lumbar spinal problems. Current surgical techniques allow for a variety of approaches to the lumbar spine and an increasingly safe and effective means of achieving bone fusion. The goal: improve your back and leg pain.