Spondylolisthesis: Is surgery a good option?

Surgery is an option if

• the symptoms are so bad that they’re making day-to-day life difficult,
• they last several months or longer,
• conservative treatment hasn’t provided enough relief, and
• diagnostic imaging (usually an MRI scan) indicates that a narrowed spinal canal is causing the problems.

Other factors to bear in mind when making your decision are your general health, age, home/work life and what you expect and hope to achieve from having surgery.

In rare cases, a narrowed spinal canal causes a medical emergency when the nerves inside it are pinched so much that you can’t move your limbs properly or your bladder or bowel stops working properly (this is called “cauda equina syndrome,” or CES). If this happens, surgery is the only possible option. But most procedures are intended to relieve symptoms, not to treat a medical emergency.

Generally speaking, the chances of back surgery being successful are quite slim. It’s difficult to predict whether a procedure will help. There are various reasons for this.

• Often, it’s still not clear what’s causing the symptoms. People who have back problems tend to have several (age-related) abnormalities in their spine. One study in Germany, for example, showed that more than 70% of 3,000 people who had MRI scans had more than one abnormality.
• An abnormality found in an MRI scan might not necessarily be the cause of the symptoms. Spinal abnormalities are almost as common in people who don’t have back or leg pain as they are in people who do. In a large-scale study, 78% of people above the age of 60 with symptoms had at least one abnormality in their spine – but so did 74% of people with no symptoms.
• It is not clear how the narrowed canal actually affects the nerves. Some experts think it puts pressure on the small vessels on the root nerves, which affects the blood supply to the nerves. Another theory is that the blood can’t flow back through the veins properly, leading to a build-up of metabolic products, which damages the nerves. The spine is a complicated structure, which can’t just be mended like a broken piece of machinery.
• Chronic pain can also be caused by other factors, like a problem with the way the brain processes pain. Psychological aspects like fear also influence the way we perceive pain. Surgery doesn’t have an effect on these types of causes.

Two different surgical techniques can be used to treat spondylolisthesis:

• Laminectomy: Laminectomy involves removing bones and ligaments that are making the spinal canal too narrow and putting pressure on the nerves. There are different procedures depending on which structures have to be removed. For instance, the surgeon might take out the entire vertebral arch or just parts of it. Bones and ligaments are important for the stability and flexibility of our spine so as little as possible is removed.

• Fusion (also referred to as “spondylodesis”): A fusion procedure is sometimes performed in addition to the laminectomy – especially if the slipped vertebra is moving back and forth (unstable spondylolisthesis). It’s done by joining together (fusing) the affected vertebrae with screws and rods to keep them in place. If the spinal disc is damaged, the surgeon removes it and uses bone or a titanium implant to fill the resulting gap between the vertebrae. You have to stay in the hospital for one to two days longer after a fusion procedure.

Fused vertebrae are less flexible than other vertebrae. But most people don’t have any major problems in their day-to-day lives because movements like bending over mostly come from the hips.

Other procedures, like dynamic stabilization or insertion of interspinous spacers, are hardly ever used for spondylolisthesis. Current medical guidelines don’t recommend them.

Laminectomy with or without fusion can be performed as an open, microsurgical or as an endoscopic procedure:

• Open surgery: The surgeon looks through a cut in the skin to see the part of the body they need to operate on. Sometimes they use a microscope (microlaminectomy). People who have this procedure are given a general anesthetic and have to stay in the hospital for a few days. The risks associated with this procedure include bleeding, nerve damage and infection. A general anesthetic may lead to complications like breathing or circulation problems.
• Endoscopic surgery: Also known as keyhole (or minimally invasive) surgery, this only requires a small cut, no more than a centimeter long. The endoscope is pushed through the cut to where the surgery is needed and then the surgeon guides micro-sized instruments through it to perform the procedure with the help of x-ray images. The idea is that the person will recover more quickly from the procedure and there won’t be any potentially problematic scars. But this procedure does have risks too, including bleeding, nerve damage and inflammation.

There has only been a small amount of good-quality research on the success rates for surgery to relieve pressure on the spinal canal. The findings can be summarized as follows:

• There hasn’t been enough good-quality research on whether surgery helps people with spinal stenosis and spondylolisthesis so the answer isn’t clear.
• It isn’t clear whether surgery or conservative treatment involving physical therapy and medication provides more relief. Studies have produced inconsistent results.
• Fusing the affected vertebrae in addition to carrying out a laminectomy doesn’t usually provide any additional benefit.
• So far, not many people with unstable spondylolisthesis have participated in the studies carried out. So it’s not clear whether fusion can help them.

The protective layers around the spinal cord can be damaged during surgery, which can result in further problems or symptoms. Other possible complications include infection, problems due to the wound not healing properly and heart attacks. If the patient loses a lot of blood during the procedure, they might need a blood transfusion.

A large-scale study looked into how often people have to go to the hospital due to complications after surgery. The results were:

• 6 to 7 out of 100 people (of whom 1 to 2 had life-threatening complications) following laminectomy, and
• 9 to 10 out of 100 people (of whom 3 to 4 had life-threatening symptoms) following fusion.

So the risk of complication is higher if a fusion procedure is carried out in addition to a laminectomy. Other risk factors are age and general health.

Surgery can also damage nerves so badly that the person becomes paralyzed, but this is extremely rare.