Sacroiliitis is an inflammation of the sacroiliac joint. Causes may include an injury, pregnancy-induced changes to ligaments, arthritis, various back or spine issues, and, in rarer cases, infection.

The sacroiliac joints are found at the lower part of your spine where it connects to your pelvic area, near the hips. Sacroiliitis can affect both joints or just one.

You may feel the pain of sacroiliitis in your:

  • buttocks
  • lower back
  • legs (one or both)
  • hips (one or both)
  • feet (not as common)

Sacroiliitis is a common development of ankylosing spondylitis. Ankylosing spondylitis is a rheumatic disease that causes joint inflammation and stiffness in the spine and hips. It’s a type of arthritis that’s progressive.

This article takes a closer look at sacroiliitis, including symptoms, causes, treatment, and outlook.

The symptoms of sacroiliitis can look similar to other lower back issues. However, sacroiliitis is specifically an inflammation in the joint.

Common symptoms include pain in your:

  • lower back
  • hip
  • buttocks
  • down the legs

The pain may get worse after standing for a long time, going up or down stairs, or running or walking with long strides.

The causes of sacroiliitis can include:

  • damage to the sacroiliac joints from falling or after a car accident
  • joints becoming loose during pregnancy to prepare for birth
  • an altered gait during pregnancy (due to hormonal changes that stretch the ligaments or how you carry the extra weight of the baby)
  • osteoarthritis and ankylosing spondylitis
  • an infected sacroiliac joint (not as common)
  • gout
  • existing back or spine issues

Sacroiliitis in pregnant people

Sacroiliitis is not uncommon in people who are pregnant. That’s because, during pregnancy, your hip and sacroiliac joints begin to naturally loosen. This is your body preparing to give birth.

Additionally, there’s a change in the way some people walk as a result of pregnancy. This can cause inflammation in the sacroiliac joints.

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Doctors use several options to accurately diagnose sacroiliitis.

Your doctor will start with a physical exam. This may include pressing in the area of your hip or your buttocks and moving your legs.

Your doctor might also send you for an X-ray to confirm. They might also order an MRI if they think you have ankylosing spondylitis.

To help identify that the pain is in your sacroiliac joint and not somewhere else in your lower back, your doctor may decide to inject a numbing medication directly into the joint. However, this is not always an accurate test since the medication can spread to other areas.

Treatment depends on the type of sacroiliitis you have. Taking over-the-counter pain medications and resting the joint can often help lower symptoms. But if you’re pregnant, check with your doctor before taking any medication.

Treatment options for sacroiliitis include:

  • alternating ice and heat to help relieve pain and inflammation
  • physical therapy and exercise
  • injections of corticosteroids directly into the joint (doctors can only prescribe these periodically due to side effects from regular use)
  • electrical stimulation of the joint using a transcutaneous electrical nerve stimulation (TENS) unit and spinal cord stimulation
  • surgery, which doctors only perform in extreme cases; for example, if the pain is due to motion through the joint, doctors might consider a fusion procedure to remove the motion and relieve pain

Medication options

If the pain is severe, your doctor may prescribe a pain medication or a muscle relaxer to help since muscle spasms are common.

Your doctor may also prescribe you a medication called a TNF inhibitor if your sacroiliitis is related to ankylosing spondylitis.

Receiving physical therapy and learning strengthening and flexibility exercises can be helpful for people with sacroiliitis.

Here are a couple of exercises that can help:

Hip flexion exercise

  1. Lay on your back with the lower part of your legs on a box or several pillows.
  2. Cross one foot over the other.
  3. Squeeze your legs together, hold, and release.
  4. Repeat this several times or as directed by your doctor or therapist.
  5. Switch legs.
  6. Lie on your back with your knees bent and your feet flat on the floor.
  7. Put a pillow between your knees, squeeze, and hold briefly.
  8. Repeat several times or as directed by your doctor or therapist.

Hip adduction isometric hold

During physical therapy, you’ll learn range-of-motion exercises and strengthening exercises. You’ll eventually be able to do many of these exercises yourself at home.

Treatment will also focus on stretching and keeping or increasing your joint flexibility. It’s always important to check with your doctor or physical therapist before trying any exercises. This is to make sure your symptoms don’t worsen or cause additional injury.

The outlook for sacroiliitis may vary based on the cause. Some injuries may improve with medications, therapy, or an exercise program.

Medication or surgery may also lower symptoms of sacroiliitis caused by joint damage. If your sacroiliitis is related to ankylosing spondylitis, treatment will be based on managing symptoms long term.

It’s a good idea to see a doctor for any pain in your joints. This is especially true if it interferes with your daily life activities. The earlier you receive treatment, the better your outcome will be.