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Does Discectomy Lead to Spinal Fusion?

If you have had a lumbar disc surgery, does that mean you will have a fusion surgery in the future?

This is a very common question asked by many.  If you have a back operation, does not mean you will have more in the future?

More specifically, if you have a lower back discectomy surgery, does that mean you will have a more significant fusion operation in the future?

As a spinal surgeon, I know that is a possibility.  But how frequently does it really happen?

This is the best way I can answer this question.  Do you have more than a 50% chance of having a fusion operation after you have had a lumbar discectomy?  The answer is a definitive no.

Before we get into the specifics, we do need to make sure everybody understands the difference between these two operative procedures.

Spinal Fusion

Discectomy means removing a piece of disc from the back, that is a source of pain.  Most the time, the reason you would have this surgery is because the disc component is pressing on a nerve and causing a very defined pain, numbness, and weakness pattern.  Statistically, properly chosen patients who undergo discectomy surgery have about a 95% chance of success after the operation.  Success being defined as a significant decrease in pain and the ability to return back to normal functions.  Please note, there may still be some residual numbness and some pain, but the person is able to get back to activities.  Currently there is about 450,000 lumbar discectomies  being performed in the United States on an annual basis.

A fusion surgery is different.  Fusion means making the body think 2 separate bones are actually a broken bone, and the body then mends the 2 broken bones together.  The reason fusions to the lower back are performed is because abnormal movements between the bones cause intermittent or constant irritations of the nerves near these bones.  The medical term is instability.  Instability can be caused by a congenital problem, degeneration, and even more serious conditions like broken bones, cancer, or infections.  Fusions are much bigger operations, and unfortunately not as predictable in their ability to return patients back to full activity compared to a discectomy.   Latest information indicates approximately 200,000 elective lumbar fusion operations being performed in the United States annually.

If you just take the raw numbers,  you can mistakenly think that anybody with a discectomy will have a moderate chance that they will have a fusion operation at a later time.  But the numbers are misleading, because many of the lumbar fusion operations are also been performed for diagnoses such as scoliosis, spondylolisthesis, spinal stenosis, and more serious conditions including cancer and infection.

In March 2019, a paper was published by Castillo, et al from the University of Chicago Medical Center.

While it was a retrospective review, it followed approximately 200,000 discectomy patients, to identify the rate these patients will have lumbar fusions, compared to a matched group of patients with similar diagnoses who did not have any operation at all.

While the patient’s with discectomy did have a higher rate of fusions overall, the actual percentage of patients with prior discectomies who ended up having fusions after 10 years was less than 9%.

The author  compared their data to other reports.   Depending on the country of origin, the fusion rates could be significantly lower.  A study from Finland had around 5%.  There has been other studies following discectomy with fusion rates significantly less than 5%.

The bottom line is the rate of fusion surgery after discectomy  is not very high.

Another factor that must be considered is the changing number of fusions that are being performed in the United States compared to the past. 

Spinal Fusions

From 2004,  to 2015,  there has been a 62% increase in the use of fusions In the USA.  While there has been some aging of the population, we cannot explain the significant increase in the use of this technique solely by clinical outcomes.

There has been enough studies to show that despite increasing utilization of advanced spine technologies and spinal operations, it has not resulted in any better clinical outcomes, return to work, return to function, or improved healthcare parameters.

Costs have significantly gone up.  Various entities have generated significant revenue from this trend. 

But,  the health of the population did not improve.  It is no wonder the payors of these expensive treatments are questioning their efficacy and justification. 

Sorry to digress, and lets get back to the main point of the video.

To summarize, while discectomy is a beneficial surgical treatment for the right patient, the concerns for needing a future spinal fusion should be taken into the context of the statistics. 

From a large population standpoint, the chances of needing fusion surgery after a lumbar discectomy is less than 10% over 10 years, in the United States.  It is even less in other first world industrial nations. 

The rates of additional fusion has also been my experience.  The vast majority of my patients did well after discectomy, especially at the L5-S1 levels.

Fusions in my practice were limited to patients who had instability secondary to spondylolisthesis, multiple recurrent disc herniations, or in the more serious conditions of infection, fracture, or tumor.

If you are having discectomy surgery, while there is potential for a fusion at a later time, the risks are relatively small.  But please have that discussion with your surgeon.

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Last modified: July 17, 2020

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