Long-Term Risks of Spinal Fusion
How Common Is It?
The numbers vary across studies, but here is what we know:
- About 5–50% of fusion patients develop visible changes on X-ray or MRI at neighboring levels
- However, not everyone with these changes develops symptoms
- The proportion who develop symptoms severe enough to require another surgery is about 20–25%
To put it simply:
- "Many people develop changes at neighboring levels, but most don't experience symptoms"
- "Those who need another surgery make up roughly 1 in 5"
Timeline of Progression
Adjacent segment changes develop gradually after fusion. The more levels that are fused, the faster these changes tend to progress.
| Time After Surgery | What Happens | Source |
|---|---|---|
| 2–7 years | 36% show changes on imaging | Jokeit M et al., 2025 |
| 5 years | Up to 80% show imaging changes | Li X-C et al., 2017 |
| Reoperation | 11% require surgery for ASD | Cho KS et al., 2009 |
Imaging changes do not equal symptoms: While up to 80% show changes on scans, these do not all cause problems. However, the risk does increase steadily over time, and a meaningful proportion of patients eventually progress to needing surgery.