A sacroiliac (SI) joint injection both treats and diagnoses lower back pain. If a doctor recommends this procedure, it can be done in an outpatient setting and may provide months of pain relief.

You have two sacroiliac (SI) joints. They’re found on opposite sides of the spine where the spine joins the ilium of your pelvis.

While they’re not hinging joints, such as your elbow or knee, SI joints still allow movement through multidirectional gliding. Factors such as aging, injury, or misalignment in the SI joint can disrupt proper function and cause pain.

In approximately 25% of people living with lower back pain, the SI joint is the culprit.

An SI joint injection has two purposes: to help verify SI joint involvement and to provide pain relief.

A doctor uses imaging technology to guide the placement of an anesthetic or an anesthetic and corticosteroid combination directly into the joint using a 5-inch needle.

Because your SI joint is hidden deep inside your body, a clear diagnostic view of the joint through imaging isn’t easy to get. Some methods are sensitive enough to help identify arthritic conditions or bone degeneration, but many people with SI joint pain may have unclear X-ray images. An MRI scan can clarify what’s unclear on an X-ray.

For this reason, pain reduction is one of the best diagnostic tools. If your pain immediately improves with the injection, it’s a good indicator that the SI joint is to blame.

SI joint injections are used to diagnose and treat pain in the lower back related to the SI joint.

Injections are the next step if your back pain hasn’t responded to a conservative spinal stabilization and stretching program, over-the-counter medications, or activity adjustments.

How do I know it’s my SI joint?

There’s no single test that can diagnose SI joint pain, but a doctor can put you through specific range-of-motion movements that help pinpoint the source of pain.

SI joint pain feels deep, and it isn’t superficial. Unlike many other lower back conditions, SI joint pain doesn’t happen gradually. It’s often linked to a specific event, such as a fall or sporting incident.

You may feel worse sitting, lying on the side that hurts, or when climbing stairs.

Pain can range from achy to jolting and often extends down into your thigh, knee, and even your foot. It can feel similar to — and is sometimes initially misdiagnosed as — pain from spinal compression conditions, which cause pressure on the spinal nerve.

In general, your pain is more likely to be SI joint related if you have a history of:

  • forceful, repetitive, or sudden twisting motions (often seen in sports)
  • heavy lifting strain
  • indirect injury from motor vehicle accidents
  • pelvic ring fractures
  • soft tissue injuries from a fall on your rear end
  • pregnancy
  • two different leg lengths
  • scoliosis
  • previous lumbar fusion
  • infection
  • osteoarthritis or spondyloarthritis
  • connective tissue enthesopathy

If any of these symptoms or risk factors sound familiar, you may be a candidate for SI joint injections.

The success rate of SI joint injections varies in research but appears to be positive for most people.

Some estimates indicate as many as 90% of people benefit from the procedure.

Despite the success rate, small variables can matter such as the type of imaging used to guide the procedure, the selected medication combinations, and factors unique to your situation. Talk with a doctor if you have concerns about how well this procedure can work for you.

Medicare, for example, requires at least 4 weeks of conservative therapies (as well as a number of other things) before approving an SI injection.

If you meet all the criteria, Medicare will cover as much as 80% of your bill. According to their database, the average cost in 2022 for an SI joint injection was between $328 and $648.

Those numbers only include the doctor fee and facility fee. The actual costs associated with SI joint injections may be much higher.

According to an older cost-effectiveness analysis from 2014, the initial doctor consultation, injection procedure, and a year’s worth of follow-up visits could cost upward of $34,000.

The most common side effect of an SI joint injection is an increase in pain or soreness.

Some people may experience an immediate but passing vasovagal response, a reflex reaction in the body that lowers heart rate and blood pressure and may cause fainting.

Other rare risks include:

It’s typical for lower back pain to return slowly as your anesthetic wears off. Depending on which medication was used, you might notice pain returning as soon as 30 minutes after the procedure or as long as 5 hours after.

Remember, the anesthetic is there to help diagnose the source of your pain. The corticosteroid is what will provide longer-term relief.

It can take up to a week for you to notice the full benefits of the steroid injection. During this time, a doctor may recommend you keep a pain diary to track your progress.

A healthcare team may also make recommendations on the use of heat or ice on the injection site, over-the-counter pain medications, activity restrictions, and any special bathing considerations.

How long does a sacroiliac joint injection last?

SI injections aren’t a cure. You’ll need multiple procedures. On average, the injections last 2 to 3 months, though some people remain comfortable longer.

What’s next if SI joint injections don’t work?

Don’t lose hope if SI joint injections don’t work for long-term pain management. Other options available if your discomfort persists include:

Was this helpful?

SI joint injections are a way to diagnose and treat lower back pain caused by the SI joint.

Performed in an outpatient setting, these anesthetic and corticosteroid treatments can help verify SI involvement and provide longer-term anti-inflammatory relief.

SI joint injections aren’t a permanent cure for SI pain. If they work well, you’ll need follow-up injections once the pain starts to return.