By Alok Sharan, MD, MHCDS, board-certified orthopedic spine surgeon · Medically reviewed November 1, 2026
Spinal fusion joins two or more vertebrae so they heal into one solid bone. It can relieve pain and restore stability when a segment of the spine is slipping or unstable. Its main risks are a fusion that doesn’t heal, wear on the levels next to the fusion, infection, and the general risks of surgery and anesthesia. For many people with spinal stenosis alone, a smaller decompression surgery works as well.
What are the pros and cons of spinal fusion?
| Pros | Cons |
|---|---|
| Stabilizes a slipping or unstable segment (spondylolisthesis, fractures, deformity) | Longer operation and hospital stay than decompression alone |
| Can reduce back and leg pain from movement at a damaged segment | The fused levels no longer move |
| Lower chance of repeat surgery than decompression alone in some patients with a slipped vertebra | More stress on the levels above and below, which can wear faster |
| Corrects alignment in deformity | The bone takes months to fully fuse |
What are the risks of lumbar spinal fusion?
The main risks are a fusion that doesn’t heal (about 5–15% of lumbar fusions), wear at the levels next to the fusion that may need more surgery, wound infection, a tear in the lining around the nerves, and the general medical risks of surgery, which rise with more complex fusions. Nerve injury is uncommon.
| Risk | How often it happens | What lowers it |
|---|---|---|
| Fusion doesn’t heal (pseudarthrosis) | About 5–15% of lumbar fusions | Not smoking; smoking roughly doubles the risk |
| Adjacent segment disease needing more surgery | 16.5% at 5 years and 36.1% at 10 years in one large series | Fusing only the levels that need it |
| Wound infection needing antibiotics | 10% with fusion vs. 4% with decompression alone, in one randomized trial | Good blood-sugar control, not smoking, smaller incisions |
| Tear in the lining around the nerves (dural tear) | 11% in the same trial, with or without fusion | Usually repaired during surgery |
| Serious medical complications in adults 65+ | 2.3% after decompression alone vs. 5.6% after complex fusion | Fewer levels, less invasive approach |
| Nerve injury | Uncommon | Careful technique and nerve monitoring |
The general risks of anesthesia, such as nausea, confusion in older adults, and breathing problems, apply to any spine surgery. Some patients can avoid them with spinal anesthesia instead of general anesthesia; see Spine Surgery Without General Anesthesia.
Do I need a fusion, or is decompression enough?
It depends on whether your spine is unstable. Two randomized trials published in 2016 reached different answers for different patients:
- Spinal stenosis, with or without a slipped vertebra (247 patients, Sweden): Adding fusion did not improve results at 2 or 5 years. It lengthened the hospital stay from 4.1 to 7.4 days and more than doubled operating costs.
- Stable grade I slipped vertebra (66 patients, U.S.): Adding fusion led to greater improvement in physical function, and fewer patients needed another operation (14% vs. 34%).
Fusion is clearly needed for an unstable spine, fractures, deformity, and some tumors and infections. Ask your surgeon to explain what in your images shows instability.
Does minimally invasive or awake fusion change the risks?
Smaller incisions and spinal anesthesia can shorten surgery and recovery and reduce pain and opioid use, but they don’t change how bone heals. Not smoking, managing diabetes, and following activity limits matter just as much.
Talk to Dr. Sharan
To find out which option fits your spine, book a consultation with Dr. Alok Sharan at the Spine and Performance Institute in Edison, NJ: call (732) 898-3950.
References
- 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. Link
- Ghogawala Z, Dziura J, Butler WE, et al. Laminectomy plus fusion versus laminectomy alone for lumbar spondylolisthesis. N Engl J Med. 2016;374(15):1424–1434. Link
- Ghiselli G, Wang JC, Bhatia NN, Hsu WK, Dawson EG. Adjacent segment degeneration in the lumbar spine. J Bone Joint Surg Am. 2004;86(7):1497–1503.
- Deyo RA, Mirza SK, Martin BI, et al. Trends, major medical complications, and charges associated with surgery for lumbar spinal stenosis in older adults. JAMA. 2010;303(13):1259–1265. Link
- Nunna RS, Ostrov PB, Ansari D, et al. The risk of nonunion in smokers revisited: a systematic review and meta-analysis. Global Spine J. 2022. Link
- Boonsirikamchai W, Wilartratsami S, Ruangchainikom M, et al. Pseudarthrosis risk factors in lumbar fusion: a systematic review and meta-analysis. BMC Musculoskelet Disord. 2024;25. Link
- Sekerak R, … Sharan A. Comparative outcome analysis of spinal anesthesia versus general anesthesia in lumbar fusion surgery. J Clin Orthop Trauma. 2021;13:122–126. Link
