Sacroiliitis (say-kroe-il-e-I-tis) is an inflammation of one or both of your sacroiliac joints — situated where your lower spine and pelvis connect. Sacroiliitis can cause pain in your buttocks or lower back, and can extend down one or both legs. Prolonged standing or stair climbing can worsen the pain. Sacroiliitis can be difficult to diagnose, because it can be mistaken for other causes of low back pain. It’s been linked to a group of diseases that cause inflammatory arthritis of the spine. Treatment might involve physical therapy and medications.

Symptoms

The pain associated with sacroiliitis most commonly occurs in the buttocks and lower back. It can also affect the legs, groin and even the feet. Sacroiliitis pain can be aggravated by:

• Prolonged standing
• Bearing more weight on one leg than the other
• Stair climbing
• Running
• Taking large strides

Causes

Causes for sacroiliac joint dysfunction include:

• Traumatic injury. A sudden impact, such as a motor vehicle accident or a fall, can damage your sacroiliac joints.
• Arthritis. Wear-and-tear arthritis (osteoarthritis) can occur in sacroiliac joints, as can ankylosing spondylitis — a type of inflammatory arthritis that affects the spine.
• Pregnancy. The sacroiliac joints must loosen and stretch to accommodate childbirth. The added weight and altered gait during pregnancy can cause additional stress on these joints and can lead to abnormal wear.
• Infection. In rare cases, the sacroiliac joint can become infected.

Complications

As with other conditions that cause chronic pain, sacroiliitis can result in depression and insomnia.