Ep. 42 Pain Procedures: Sacroiliac Joint (SIJ) Blocks
Episode Summary:
In this episode of 'It's Not In Your Head,' co-host Justine Feitelson and Dr. Dan Bates recap the five major causes of lower back pain and dive into performing sacroiliac joint (SIJ) procedures, specifically diagnostic blocks. They cover the efficacy of single versus double blocks, and potential treatments depending on the result of the block like radiofrequency neurotomy and prolotherapy. Additionally, they explore the decision-making process for patients, the economic considerations, and the rarity of SIJ fusions in different regions. Tune in for an in-depth look at how to use diagnostic blocks to confirm SIJ dysfunction and arrive at a more specific diagnosis.
Episode Overview
This episode explains how sacroiliac joint (SIJ) diagnostic injections are used to pinpoint whether the SIJ is the actual source of lower back/buttock pain and how that guides further treatment and rehab planning.
Big picture: Why SIJ blocks?
Dan and Justine continue their series on turning “non‑specific” back pain into specific diagnoses, focusing here on sacroiliac joint (SIJ) procedures.
There are five main causes of lower back pain: facet joints, sacroiliac joints, hips, discs, and nerves, with pain location (above vs below the belt line, and leg vs back dominance) helping decide where to start.
SIJ blocks are mainly used when pain is below the belt line (often felt as buttock pain) and SIJ pathology is suspected, to confirm whether the joint is really driving the pain before committing to more invasive or costly therapies.
What kinds of SIJ problems?
Dan groups SIJ causes into three main buckets: inflammatory disorders, osteoarthritis, and SIJ dysfunction (a “wobbly” or unstable joint).
The SIJ is a flat, interlocking joint at the base of the spine that carries huge load, normally moving only about 1–4 degrees and should stay mostly put.
Pain patterns from different low back structures overlap, so clinical rules of thumb are helpful but often not enough, which is why targeted diagnostic injections are needed.
What exactly is injected?
Dan describes two pain-generating structures: the joint itself and the strong dorsal interosseous ligament at the back of the joint, which also becomes very painful.
Most of the world tends to inject only the joint, but Dan was trained to inject both the bottom of the joint and the dorsal interosseous ligament, and that remains his usual practice.
Because the SIJ is tight and flat, even when “wobbly,” getting into the joint can be technically challenging, which contributes to variation in how clinicians perform the procedure.
How accurate is an SIJ block?
A “positive” block is when the injection leads to a large, temporary reduction in pain (often 50–100% relief), indicating the injected structure is probably the main pain source.
There is a significant false positive rate (about 20–40%), partly due to brain and expectation effects, which is similar to the false positive rate for medial branch blocks (around 35%).
Some guidelines therefore suggest doing two blocks (an initial and a confirmatory block), but Dan emphasizes balancing diagnostic certainty against cost and practicality.
Single vs double block and health economics
Dan cites clinic data (pre‑2013) showing that a single SIJ block gave roughly an 88% likelihood that pain was coming from the SIJ, and a double block increased that to about 90%.
Because that gain in certainty is small, his practice is to do a single block and then move on to treatment, especially when the initial response is very strong.
Doing more blocks is not only expensive but also raises larger health‑economics questions for both patients and insurers.
When do people get to this point?
In Dan’s practice, most patients have already tried conservative care (physio, chiro, osteopathy, etc.) and various providers before seeing him, partly because there are relatively few clinicians doing these procedures.
There are multiple clinical tests to suggest SIJ pain and to help distinguish between instability and arthritis, and that diagnostic clarity should ideally guide conservative rehab as well, and not just be labeled “non‑specific back pain.”
For patients who really want diagnostic certainty before committing to rehab or more invasive options, Dan is comfortable using a block first to clarify what driving the pain so all treatments can be more effective.
Risks, costs, and why diagnosis matters
Dan emphasizes that every intervention carries its own risks: radiofrequency (RF) can cause burning pain afterward and a small risk of infection, while prolotherapy carries financial costs and usually requires a series of injections.
Because of this, he wants a clear diagnosis before asking patients to commit to multi‑session, costly or higher‑risk therapies, which blocks help clarify.
He has moved away from assuming “you look unstable so we’ll fix biomechanics first and only intervene later,” because some people with apparent SIJ instability are actually not in SIJ‑driven pain and would not benefit from those targeted procedures.
How Dan actually runs the injections
If Dan suspects SIJ osteoarthritis, he injects local anesthetic plus cortisone, hoping for potentially up to about six months of reduced pain, and gives patients a two‑week pain diary to track effect.
If he suspects pure SIJ dysfunction/instability, he does not use cortisone because it is catabolic (breaks down tissue, including ligaments) and might worsen looseness; in that case the goal is purely diagnostic and he uses a six‑hour pain chart to watch pain go away and then return.
Follow‑up typically occurs within two weeks to review the pain charts and then decide on next steps (e.g., RF, prolotherapy, or continued rehab).
Linking procedures with rehab
If SIJ osteoarthritis is confirmed and the diagnostic block does not give long‑term relief, Dan often proceeds to radiofrequency neurotomy as a longer‑term pain‑reducing option.
For confirmed instability, he discusses prolotherapy as a controversial but potentially helpful way to support the joint, though it usually requires a series of about three injections and is financially demanding. Check out our episode on Prolotherapy for more on that.
Procedures reduce pain but do not recondition the body, so once pain is controlled the priority is to take advantage of that window and get going with rehab, exercise, and strength work to restore function long-term.
Rehab “algorithm” and when to escalate
Dan’s simple rehab rule: if you’re doing rehab and steadily improving, keep going; if every attempt flares symptoms badly, it’s time to take a different angle.
If a patient has plateaued despite a good effort and compliance, he suggests choosing reasonable guardrails: around three months of consistent rehab is a logical point to reconsider the diagnosis or add interventions (shorter than six months, longer than six weeks).
This approach is meant to avoid both endless wheel‑spinning in rehab that never progresses and premature escalation to invasive procedures.