The Long-Term Side Effects of Spinal Fusion
On this page:
- The structure of the spine
- Fusion can cause adjacent segment disease
- The long-term side effects of spinal fusion
The purpose of a spinal fusion is to stop movement. A one-level fusion removes the disc between two vertebrae and uses screws and other hardware to force the two vertebrae together, which then fuse into one structure. A two-level fuses three vertebrae, three-level fuses four vertebrae, and so on. So is it really that big of a deal if we lose movement and flexibility in a few vertebrae?
Yes, it’s a big deal, and the risks are long-term. Let me explain.
The Structure of the Spine
The spine consists of a column of stacked bones called vertebrae, and the column stretches from the neck all the way down to the tailbone. There are five segments: cervical (7 bones), thoracic (12 bones), lumbar (5 bones), sacrum (5 fused bones), and coccyx (the 4 fused bones that make up the tailbone).
Their purpose is to provide structure for the body and to protect the big bundle of nerves that threads through the middle of the column called the spinal cord. Between each vertebra, we have intervertebral discs, which cushion the vertebrae as we move and absorb shock.
While the terminology spinal column likely brings to mind a stick-straight structure, the spinal column is not straight. It actually has gentle snake-like curves to the front and back that provide counterbalance and aid with movement, balance, and shock absorption. In short, the spinal column is made for flexibility and movement.Learn about Regenexx procedures for spine conditions.
Fusion Can Cause Adjacent Segment Disease
A fusion forces the adjacent vertebral segments (those above and below the fusion) to take on the extra stress and become overloaded with additional work they were never intended to do. When this occurs, this is called adjacent segment disease (ASD), and it may be accompanied by pain, bone spurs, arthritis, and so on.
As it advances, you’re likely to start hearing your doctor throw out the F word again — another fusion. And next thing you know, you’re chasing your ASD up or down your spine.
So, yes, one fusion is one fusion too many. And if you’ve already had one fusion, this doesn’t mean you have to say yes to another one. In fact, the long-term fusion risk is that it will just create bigger and bigger problems down the road (1). See the video below for visuals and more information on ASD.
The Long-Term Side Effects of Spinal Fusion
A September 2018 study investigated the occurrence of adjacent segment disease (ASD) following short lumbar fusion surgery (2). Specifically, how often does ASD following fusion result in additional fusions? The study defines “short fusion” as three or fewer fused levels. Researchers followed 479 subjects after short fusions. A total of 37 subjects (7.7%) underwent surgeries for ASD that developed after their initial fusion surgery.
The study found that subjects whose initial fusion included three segments were 2.7 times more likely to undergo ASD fusion surgery than those with one or two fused segments. So the more lumbar levels you have fused, the more likely you are to need additional fusions. Additionally, subjects with rheumatoid arthritis fared even worse, with a 4.5 times greater risk of more fusions.
Adjacent segment disease aside, long-term fusion risk includes many additional important issues, including:
- Indicators such as pain, quality of life, and disability have been shown to be no better with a fusion than they are with conservative approaches alone (3).
- Physical therapy (PT) was shown to be just as effective at relieving pain and restoring function as a back fusion (4).
- Two- and five-year post-surgery outcomes were no better for patients with fusions than for those who only underwent a laminectomy (decompression) (1).
Fusing a spine to treat pain is NEVER a good thing and should be avoided at all costs. As a patient, please be smarter and get multiple opinions from both spine surgeons and non-surgeons who don’t know each other. Know ALL your options.
(1) Försth P, Ólafsson G, Carlsson T, et al. A Randomized, Controlled Trial of Fusion Surgery for Lumbar Spinal Stenosis. N Engl J Med. 2016;374(15):1413-1423. doi:10.1056/NEJMoa1513721
(2) Park JS, Shim KD, Song YS, Park YS. Risk factor analysis of adjacent segment disease requiring surgery after short lumbar fusion: the influence of rheumatoid arthritis. Spine J. 2018;18(9):1578-1583. doi:10.1016/j.spinee.2018.02.005
(3) Hedlund R, Johansson C, Hägg O, Fritzell P, Tullberg T; Swedish Lumbar Spine Study Group. The long-term outcome of lumbar fusion in the Swedish lumbar spine study. Spine J. 2016;16(5):579-587. doi:10.1016/j.spinee.2015.08.065
(4) Lurie JD, Tosteson TD, Tosteson A, et al. Long-term outcomes of lumbar spinal stenosis: eight-year results of the Spine Patient Outcomes Research Trial (SPORT). Spine (Phila Pa 1976). 2015;40(2):63-76. doi:10.1097/BRS.0000000000000731