An image-guided injection into the joint between your spine and pelvis — used both to find out whether the SI joint is the source of your pain and to treat it.
The sacroiliac joints are the two small, strong joints that connect the base of your spine (the sacrum) to your pelvis. They're built more for stability than for motion, but they can become a real source of pain — usually on one side — particularly after pregnancy, trauma, a long career of heavy lifting, or previous lumbar fusion surgery (where the joints above are now doing less work and the SI joint takes on more load).
An SI joint injection places a small amount of local anesthetic, usually combined with a corticosteroid, directly into the joint using fluoroscopic (live X-ray) guidance. The injection has two purposes: a diagnostic one — does numbing the joint relieve your pain? — and a therapeutic one — the steroid can quiet inflammation in and around the joint for weeks to months.
The honest truth about SI joint pain is that the diagnosis can be tricky. The physical exam tests aren't perfect, imaging is often unrevealing, and pain in this region can come from the lumbar spine, the hip, or the muscles around the pelvis. The clearest way to confirm the SI joint is the problem is to numb it and see what happens. That's why an injection is often both the test and the treatment.
An SI injection is generally not the right next step if there's active infection at or near the joint, if the pain pattern points clearly to the lumbar spine or hip instead, or if you're on certain blood thinners that haven't been managed beforehand. Poorly controlled diabetes is not a hard stop, but we plan around the temporary blood-sugar bump that steroids can cause.
You'll lie face-down on the fluoroscopy table. We'll position you comfortably with a small pillow under your hips so the joint is easy to access.
The skin is cleaned and numbed with local anesthetic. You'll feel a small sting from the numbing medication, then mostly pressure after that.
Using live X-ray and a small amount of contrast dye, the needle is guided precisely into the joint to confirm placement before any medication goes in.
A combination of local anesthetic and corticosteroid is injected. You'll rest briefly afterward — total visit time is about 30 to 45 minutes.
You can walk out and go home the same day; you'll just need a driver if you've had any sedation. The area may be a little sore for one to two days where the needle went in. Most patients return to normal activity the next day.
If this is a diagnostic injection, the first four to six hours are the most informative — that's when the anesthetic is at peak effect. We'll ask you to keep a simple pain diary: rate your pain before the injection and at intervals afterward, and ideally try the activities that usually provoke your pain (carefully). A clear, substantial drop during that window strongly suggests the SI joint really is the source.
The steroid takes effect over the next two to seven days. Relief can last weeks to several months. If the first injection helps but the benefit fades, the injection can usually be repeated. For pain that keeps coming back, we may discuss radiofrequency ablation of the SI nerves or, in selected cases, SI joint fusion.
SI joint injections are generally safe. Possible issues include a temporary increase in pain for a day or two, bleeding or bruising at the needle site, and a small risk of infection. Steroid-related side effects can include transient blood-sugar elevation in diabetics, facial flushing, a few nights of disrupted sleep, and occasionally menstrual irregularity. We'll review the specific risks for your situation and answer questions before we proceed.
KeyTone Medical is out of network with all commercial health insurance plans, so this procedure is self-pay, with the cost discussed before anything is scheduled. Many plans reimburse part of the cost of medically necessary care performed out of network — on request we provide a superbill, an itemized and coded receipt, for you to submit to your insurer under your plan's guidelines.
We piece it together from where the pain is, what makes it worse, the physical exam, and what your imaging does (and doesn't) show. Because none of those is definitive on its own, a diagnostic injection — numbing the joint and watching what happens to your pain for the next several hours — is often the most reliable confirmation.
It varies. A successful steroid injection often gives weeks to several months of relief — sometimes longer. Some patients get one injection and stay better. Others need a repeat injection every few months, or eventually move on to radiofrequency ablation for longer-lasting relief.
The facet joints sit at the back of the spine itself and tend to cause more midline back or neck pain. The SI joints sit lower down, where the spine meets the pelvis, and tend to cause pain on one side over the buttock or posterior thigh. They're different sources of pain that often get lumped together as "low back pain" — and they sometimes coexist, which is why diagnosis matters.
Maybe. If the first injection clearly helps and the relief lasts a meaningful amount of time, we'll consider repeating it if your pain comes back. If the first injection confirms the SI joint as the source but the relief is short-lived, we'll talk about whether radiofrequency ablation or, in some cases, SI joint fusion makes sense.
Most patients describe it as uncomfortable rather than truly painful. You'll feel the sting of the numbing medication, then pressure as the needle is guided into the joint. The X-ray guidance makes the placement quick and precise. Mild sedation is available if anxiety is a concern, but most people manage well with local anesthetic alone.
Authoritative references on this topic, for patients who want to read further. These are educational resources, not medical advice.
Educational information only. This page describes the sacroiliac joint injection in general terms. Whether it's appropriate for you depends on your history, exam, imaging, and treatment goals. The risks, benefits, alternatives, and expected results will be discussed in detail at your visit.
