The pain of sacroiliitis most often occurs in the buttocks and lower back. It also can affect the legs, groin and even the feet. The pain can improve with movement. The following can make sacroiliitis pain worse:

• Sleeping or sitting for a long time.
• Standing a long time.
• Having more weight on one leg than the other.
• Stair climbing.
• Running.
• Taking large steps when moving forward.

Causes for sacroiliac joint issues include:

• Injury. A sudden impact, such as a motor vehicle accident or a fall, can damage the sacroiliac joints.
• Arthritis. Wear-and-tear arthritis, also known as osteoarthritis, can occur in sacroiliac joints. So can a type of arthritis that affects the spine, known as ankylosing spondylitis.
• Pregnancy. The sacroiliac joints loosen and stretch for childbirth. The added weight and changed way of walking during pregnancy can stress these joints.
• Infection. Rarely, a sacroiliac joint can become infected.

Certain conditions may increase the risk of swelling in the sacroiliac joints.

Inflammatory forms of arthritis, such as ankylosing spondylitis and psoriatic arthritis, may increase the risk of sacroiliitis. Inflammatory bowel diseases, including Crohn's disease and ulcerative colitis, also may increase the risk.

Changes that happen to the body during pregnancy and childbirth also can stress the sacroiliac joints and cause pain and swelling.

Sacroiliitis can cause difficulty with certain actions, such as bending, lifting, staying in one position and rising from being seated. The ongoing pain of sacroiliitis can lead to depression and loss of sleep.

During the physical exam, a health care provider might press on the hips and buttocks to find the pain. Moving legs into different positions gently stresses the sacroiliac joints.

Imaging tests

An X-ray of the pelvis can show signs of damage to the sacroiliac joint. An MRI can show whether the damage is the result of ankylosing spondylitis.

Numbing shots

If putting numbing medicine into the sacroiliac joint stops the pain, it's likely that the issue is in the sacroiliac joint.

Home treatments for sacroiliitis pain include:

• Pain relievers you can get without a prescription. Medicines such as ibuprofen (Advil, Motrin IB, others) and acetaminophen (Tylenol, others) may help relieve the pain of sacroiliitis. Some of these medicines can cause stomach upset, or kidney or liver problems.
• Rest. Changing or not doing the activities that worsen pain might help. Using good posture is important.
• Ice and heat. Switching between ice and heat might help relieve sacroiliac pain.

You might start by seeing your primary care provider. You might be referred to a specialist in bones and joints, known as a rheumatologist, or an orthopedic surgeon.

What you can do

Take a family member or friend along, if possible. Someone who's with you can help you remember the information you get.

Make a list of:

• Your symptoms and when they began.
• Key information, including recent life changes and whether any first-degree relative has had symptoms like yours.
• All medicines, vitamins or other supplements you take, including doses.
• Questions to ask your care provider.

For sacroiliitis, questions to ask include:

• What's likely causing my symptoms?
• What are other possible causes?
• What tests do I need?
• Is my condition likely temporary or chronic?
• What's the best treatment?
• How can I manage this condition with my other health conditions?
• Are there restrictions I need to follow?
• Should I see a specialist?
• Are there brochures or other printed materials I can have? What websites do you recommend?

Ask other questions you have.

What to expect from your doctor

Your care provider might ask you questions, such as:

• Have your symptoms been continuous or occasional?
• Where exactly is the pain? How bad is it?
• Does anything make the pain better? Does anything make it worse?