Sacroiliac (SI) joint injections can be used to diagnose and treat low back pain that is believed to be caused by irritation and inflammation of an SI joint. In the lower back, there are two sacroiliac joints that connect the spine to the pelvis. While these joints do not move, they support much of the body’s weight. Therefore, the SI joints are prone to degeneration.

How is the procedure performed?

When performing a sacroiliac injection, a physician will use fluoroscopy (X-ray guidance) to precisely place a needle into the SI joint. The physician will then administer an injection of dye to confirm the proper placement of the needle, followed by an injection of a medication mixture consisting of a local anesthetic and anti-inflammatory (steroid). The goal is to reduce SI joint inflammation and alleviate pain.

The results and what they mean

After an SI injection, if a patient’s symptoms temporarily resolve due to the effects of the anesthetic, a physician can usually confirm that the sacroiliac joint is the pain generator. Alternatively, if the patient’s symptoms decrease significantly but do not completely go away, a physician may conclude that the sacroiliac joint is either the source of, or a contributor to, the patient’s pain.

It can take more time — a few days up to one week — to see the effects of the long-acting steroid medications. Many patients find that their symptoms improve to the point that they are able to perform daily activities and participate in physical therapy without pain, and the resulting relief may last for up to several months. This is important because physical therapy, which is often a key component of SI joint pain treatment, can potentially maximize or prolong the benefits of sacroiliac joint injections.

While generally safe and well tolerated, SI injections are not appropriate or effective for everyone. If you’re experiencing low back pain, your physician can help you determine if sacroiliac joint injections are right for you or recommend a suitable alternative.