The term sacroiliitis is used to describe any inflammation in the sacroiliac joint, which is located on either side of the sacrum (lower spine) that connects to the iliac bone in the hip.
Sacroiliitis is often found as part of a feature of inflammatory conditions of the spinal column. As a group, these conditions and diseases are termed a "spondyloarthropathy" and include conditions such as ankylosing spondylitis, psoriatic arthritis, and reactive arthritis, among others.
Sacroiliitis may also be a component of other types of arthritis, such as ulcerative colitis, Crohn’s disease, or osteoarthritis.
Sacroiliitis is also a term that is sometimes used interchangeably with the term sacroiliac joint dysfunction, as technically either term can be used to describe pain that stems from the sacroiliac joint (or SI joint).
Sacroiliitis vs. Sacroiliac Joint Dysfunction
Both sacroiliitis and sacroiliac joint dysfunction are a common cause of sacroiliac pain, low back pain, and leg pain.
However, there are differences between the two conditions:
- Sacroiliitis. In medicine, the term “itis” refers to inflammation, and sacroiliitis describes inflammation of the sacroiliac joint. The inflammation may or may not be caused by sacroiliac joint dysfunction.
- Sacroiliac Joint Dysfunction. This condition generally refers to pain in the sacroiliac joint region that is caused by abnormal motion in the sacroiliac joint, either too much motion or too little motion. It typically results in inflammation of the SI joint, or sacroiliitis.
The most common symptoms of sacroiliitis include some combination of the following:
- Pain, usually low back pain, leg pain (may be in the front of the thigh), hip pain, and/or buttock pain
- Pain that is worse when sitting for a long time, and worse when rolling over in bed
- Stiffness felt in the hips and low back, especially after getting out of bed in the morning or after sitting still for a prolonged period.
A wide range of factors may cause sacroiliitis or predispose one to developing sacroiliitis:
- Any form of spondyloarthropathy, which includes ankylosing spondylitis, arthritis associated with psoriasis, and other rheumatologic diseases, such as lupus
- Degenerative arthritis, or osteoarthritis of the spine, causing degeneration of the sacroiliac joints and in turn leading to inflammation and SI joint pain
- A trauma that affects the lower back, hip or buttocks, such as a car accident or fall
- Pregnancy and childbirth, as a result of the pelvis widening and stretching the sacroiliac joints during childbirth
- Infection of the sacroiliac joint
- Urinary tract infection
- IV drug use/drug addition
If a patient has pain in the sacroiliac area and any of the above conditions, he or she may have sacroiliitis or sacroiliac joint dysfunction.