Longer-lasting relief for confirmed sacroiliac joint pain.
What is SI joint ablation?
Once diagnostic injections and lateral branch blocks confirm the joint is the source, the next step comes. Radiofrequency energy interrupts the small nerves that carry its pain signal.
PRP and the other orthobiologics we use for the low back and pelvis are explained on our PRP injections in St. Louis page.
What we use it for
- Confirmed sacroiliac joint pain
- Persistent one-sided low back pain after lumbar fusion
- Sacroiliac pain after a fall
What should I expect from SI joint ablation?
- 30 to 45 minutes under fluoroscopy.
- Soreness for one to two weeks is expected.
- Benefit typically begins at two to three weeks and lasts many months.
- No sedation; most patients drive themselves home.
What is the downside of SI joint radiofrequency ablation?
The lateral branches that feed the sacroiliac joint vary in position more than the medial branches of the spine. So a larger area is treated. That makes soreness across the buttock after the procedure more noticeable, usually for one to two weeks. Numbness over the upper buttock is common and usually goes away. Because the target nerves vary from person to person, somewhat fewer people respond than with lumbar facet ablation. That is why confirmatory blocks (blocks that confirm the source) beforehand are not optional.
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How we judge whether it worked
Confirming the source matters more here than almost anywhere, because the anatomy varies. Lateral branch blocks have to show clear, reproducible relief before ablation is justified.
When they do, how long relief lasts is comparable to facet ablation. This is often the lasting answer for one-sided low back pain that showed up after a lumbar fusion.
Before and after your procedure
No sedation is used, so most patients drive themselves home. Expect buttock soreness for one to two weeks, sometimes more noticeable than after spinal ablation because a larger area is treated. Sitting on hard surfaces will be uncomfortable for several days. A cushion helps. Benefit begins at two to three weeks. Resume walking early; prolonged rest is unhelpful here.
How is SI joint ablation done?
The sacroiliac joint gets its nerve supply from the lateral branches of the sacral nerves. These fan across the back of the sacrum. Ablation uses radiofrequency energy to make small lesions (tiny heat spots) along that path. It is usually done as a strip, not a single point, because the nerve supply varies from person to person. It is done under fluoroscopic guidance (live X-ray). It takes longer than a simple block. It follows positive diagnostic blocks. It never comes before them.
Who is a candidate for SI joint ablation?
It suits patients whose sacroiliac joint was confirmed as the pain source by diagnostic blocks. Their relief from those blocks should have been strong but short. It does not suit patients who have not had confirmatory blocks, because the success rate without them falls sharply. It also does not treat a loose, unstable joint.
Preparing for the appointment
Bring your current imaging on a disc or through a portal. Bring a full list of your medications, including anything from another doctor and any blood thinners. Bring a note of previous injections and how long each one helped. Blood thinners may need planning around, so tell us ahead of time, not on the day.
Common questions
Why is the sacroiliac joint so often the answer after fusion?
A fused segment of the low back does not move. So the load shifts to the joints below it. New one-sided low back pain after fusion often comes from the sacroiliac joint.
The injection used to confirm the joint is described in Sacroiliac Joint Injection.
How long does the relief last?
Often six to twelve months. The nerves grow back, and symptoms return slowly. The procedure can be repeated.
There is more on this in Radiofrequency Ablation.
Why is the sacroiliac joint harder to ablate than the facets?
Because its nerve supply varies between people and covers a wider area. So lesions are made along a strip, not at one predictable point.
There is more on this in Sacroiliac Joint Pain.
Do I definitely need blocks first?
Yes. Ablation performed without confirmatory blocks has a clearly lower success rate. The blocks take just one extra visit.
How long does it take to recover from SI joint ablation?
Expect buttock soreness for one to two weeks. It can feel stronger than after spine ablation because a wider strip is treated. Hard chairs will be uncomfortable for several days, so bring a cushion. Relief usually starts at two to three weeks. Get up and walk early; long bed rest does not help this recovery. No sedation is used, so most patients drive themselves home on the day.
Sources
- McCormick ZL et al. Consensus practice guidelines on sacroiliac joint complex pain from a multispecialty, international working group. Pain medicine (Malden, Mass.), 2025. PubMed 41318933
- Chen CH et al. Radiofrequency neurotomy in chronic lumbar and sacroiliac joint pain: A meta-analysis. Medicine, 2019. PubMed 31261580
- Szadek K et al. 5. Sacroiliac joint pain. Pain practice : the official journal of World Institute of Pain, 2024. PubMed 38155419
- Leggett LE et al. Radiofrequency ablation for chronic low back pain: a systematic review of randomized controlled trials. Pain research & management, 2014. PubMed 25068973
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