What causes spinal fusion complications years later? A failed lumbar fusion? Since I see this problem almost every day in the clinic, there are some big categories of issues you should know about. Let’s dig in.
What is Lumbar Fusion?
Lumbar fusion means that you take a part of the spine that’s painful and bolt it together and add bone so it grows together and doesn’t move (2). Commonly hardware is added to enhance the stability while the disc spaces and other areas grow bone. These days we’re also seeing doctors using recombinant growth factors like BMP (Bone Morphogenic Protein) to help bones fuse. For a common low back fusion x-ray, see the image here.
What Are the Symptoms of a Failed Lumbar Fusion?
The most common thing we see in the clinic in patients who have spinal fusion complications years later is either a return of back pain or new symptoms. These both indicate possible new disease. What are some good examples?
- A return or worsening of low back pain
- New symptoms like pain in another place or new numbness and tingling or referred pain down the leg
- New weakness in the leg
- New loss of function like an inability to exercise without pain
The Categories of Spinal Fusion Complications Years Later
The problems fall into two main categories: ASD and muscular stabilization failure. There are also other less common categories that we’ll discuss. These include failure to fuse and hardware problems.
What is ASD?
Adjacent Segment Disease (ASD) simply means that the area above and below the fusion is getting overloaded (3). This happens when one part of the spine is fused and the energy and movement that used to be handled by that segment has to get shunted somewhere. Hence, it tends to go above and below the fusion leading to an overload of those areas and more wear and tear. For more information, see my video below:
The biggest tip-off that you have ASD is that new problems crop up. Many times this is new pain above or below the fusion. Other times it’s a new problem like numbness or tingling, or pain shooting down a leg. ASD solutions will be discussed below.
I saw a patient in the clinic this past week who had two fusion surgeries. When I looked at her MRI (above) she was dumbfounded when I showed her that her back muscles in the area of the fusions had died off completely. She knew that wasn’t good. So is this a thing?
A recent study looked at the effects of single-level fusions on spine muscle health (1). What did they find? That the low back muscles had atrophied (read got smaller) and had shrunk about 50% due to the surgery! What are the implications of this?
These muscles are used to help bend over, pick up things, and carry stuff. When they atrophy, it becomes tough to do these things. Hence, the loss of these muscles is not a good thing.
Other Post Fusion Problems
These issues break into a couple of categories:
- Failed fusion
- Hardware problems
Remember that low back fusion involves back bones (vertebrae) growing together. Hence, it’s possible that the bones didn’t fuse together. How often does this happen? The usual rate of non-fusion is about 5-10%. However, for procedures that need more bone (i.e. a posterior-lateral fusion), the failure to fuse rates can be as high as 26% to 36% (4,5).
Loosening of the hardware, breakage of that metal, and pain caused by those issues are a common reason subsequent surgeries are performed after an initial fusion. How often does that happen? About 1 in 10 patients who have had a low back fusion need a second surgery to fix these issues (6).
Can These Problems Be Fixed Without Additional Surgery?
The short answer is yes. For example, we treat ASD quite frequently by using newer interventional orthopedic techniques above and below the fusion. What’s that?
We use natural substances derived from the patient’s body like growth factors derived from platelets to prompt or stimulate healing in these beat-up areas. These injections are placed precisely with fluoroscopy or ultrasound. The problem with using more traditional approaches is that things like steroids and radiofrequency can harm and break down spine tissue.
The upshot? Spinal fusion complications years later can have lots of causes. Hence, if you have new or returned problems, getting to the bottom of “why” is key. Also, injections can help but stick with those that can help stimulate repair rather than those that break down tissue.
(1) Cho, S., Kim, S., Ha, S. et al. Paraspinal muscle changes after single-level posterior lumbar fusion: volumetric analyses and literature review. BMC Musculoskelet Disord 21, 73 (2020). https://doi.org/10.1186/s12891-020-3104-0
(2) Daniel Yavin, MD, Steven Casha, MD, PhD, Samuel Wiebe, MD, MSc, Thomas E Feasby, MD, Callie Clark, MSc, Albert Isaacs, MD, Jayna Holroyd-Leduc, MD, R. John Hurlbert, MD, PhD, Hude Quan, MD, PhD, Andrew Nataraj, MD, Garnette R. Sutherland, MD, Nathalie Jette, MD, MSc, Lumbar Fusion for Degenerative Disease: A Systematic Review and Meta-Analysis, Neurosurgery, Volume 80, Issue 5, May 2017, Pages 701–715, https://doi.org/10.1093/neuros/nyw162
(3) Saavedra-Pozo FM, Deusdara RA, Benzel EC. Adjacent segment disease perspective and review of the literature. Ochsner J. 2014;14(1):78–83. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3963057/
(4) Herkowitz HN, Kurz LT. Degenerative lumbar spondylolisthesis with spinal stenosis. A prospective study comparing decompression with decompression and intertransverse process arthrodesis. J Bone Joint Surg Am. 1991 Jul; 73(6):802-8. https://www.ncbi.nlm.nih.gov/pubmed/2071615/
(5) Tsutsumimoto T, Shimogata M, Yoshimura Y, Misawa H. Union versus nonunion after posterolateral lumbar fusion: a comparison of long-term surgical outcomes in patients with degenerative lumbar spondylolisthesis. Eur Spine J. 2008;17(8):1107–1112. doi: 10.1007/s00586-008-0695-9
(6) Greiner-Perth R, Boehm H, Allam Y, Elsaghir H, Franke J. Reoperation rate after instrumented posterior lumbar interbody fusion: a report on 1680 cases. Spine (Phila Pa 1976). 2004 Nov 15;29(22):2516-20. https://www.ncbi.nlm.nih.gov/pubmed/15543064