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Sacroiliac Joint Disorder; An Often Missed Source Of Back Pain

Sacroiliac Joint Disorder: Is that why your back hurts?

Low back pain is very common and affects approximately 70% of people in their lifetime (1). For anyone who has experienced low back pain, it can be very disabling. But sometimes low back pain is not “spine pain.” The sacroiliac joint (SIJ) often can be the pain generator and may be missed if all of the focus is on the lower spine. Studies have shown that in 13-30% of individuals with chronic low back pain, the sacroiliac joint was found to be the source of their pain (1).  So out of 10 patients seen in a physician’s office for low back pain, the sacroiliac joint is the culprit in 2-3 patients.

Sacroiliac Joint: What is it?

The sacroiliac joint is wedged shaped and joins the spine to the pelvis. It is a diarthrodial joint connecting the sacrum to the ilium and contains synovial fluid and is surrounded by a fibrous capsule.  Its job is to absorb forces from the spine and transfer them to the pelvis and lower extremities and vice versa. It is only 1-2mm wide and moves only minimal amounts, about 2-3 degrees. There is some debate about which nerves innervate the sacroiliac joint but there is agreement that there are nerve receptors in the joint which transmit both pain and position sense (1, 2).

Clinical Presentation:

Some of the common causes of sacroiliac pain include falling directly on the buttock; a rear-end motor vehicle accident with the foot on the brake or a broadside accident with a blow to the side of the pelvis; stepping into a hole or a misstep (2). Athletes in sports who require unilateral loading with kicking or throwing, or landing on one leg (figure skater) have a higher risk. It has been found to be more common in cross country skiers and rowers. During pregnancy, the combination of hormones increasing the laxity of the joint, weight gain, and altered posture increases the frequency of sacroiliac problems. In addition, individuals with certain types of polyarthritis are at risk for sacroiliac problems (1, 2).

Persons with sacroiliac pain often report pain in the low back and buttock. Usually the pain is 3-10cm below the posterior superior iliac spine and typically doesn’t go above the beltline. Pain is usually unilateral compared to bilateral in a 4:1 ratio. Some individuals report numbness, popping, clicking, and groin pain. Some feel there may be some communication between the SIJ and nearby nerve structures. This may explain why pain may be referred into the buttock and lower extremities at times (1,2).

Diagnosis of Sacroiliac Joint Problems

Many studies have been done evaluating what examination techniques are the most accurate at diagnosing sacroiliac joint problems. Some of the sacroiliac clinical tests used to diagnose include FABER, distraction/ compression tests, focal SIJ tenderness, femoral shear tests, modified Gaenslen’s and others. When 3 or more tests are positive it increases the probability that the SIJ is the source of the pain. Unfortunately, studies show that even a combination of positive tests still is not very accurate at diagnoising SIJ pain. Diagnostic imaging with X-rays, CT, and MRI are most useful in ruling out other causes of pain such as fractures, tumors, and inflammatory arthritis as is appropriate screening blood tests (1-2).

Fluoroscopically (X-ray) guided SIJ injections are felt to be the closest thing to a “gold standard” for confirming SIJ problems. It is extremely important to have the injection done with imaging guidance by a person trained in the protocol of doing SIJ injections. SIJ injections without fluoroscopy were shown to be in the sacroiliac joint only 22% of the time (1).

Treatment of Sacroiliac Joint Disorders

In the acute period, conservative care includes icing, relative rest, anti-inflammatory medications, and appropriate pain medications. As pain begins to subside in the recovery phase, the goal is to maximize function despite the pain. Pelvic stabilization exercises and muscle balancing in physical therapy and possibly manipulation with manual medicine can help restore normal SIJ mechanics.  A sacroiliac joint belt often can help provide stability, position sense, and decrease pain (1,2).

When some of the above treatments fail or are less effective, a fluoroscopically guided SIJ intra-articular injection with corticosteroid can help therapeutically and diagnostically.  These injections often can help avoid unnecessary tests and surgery, reduce pain, and facilitate rehabilitation (2).

Other treatments that are being studied include radiofrequency neurotomy, prolotherapy, cryotherapy, and surgical fixation (arthodesis) of the joint. Research is ongoing, but there is limited evidence on the effectiveness of these treatments (2).


The sacroiliac joint is a common and often overlooked source of low back pain. At Sierra Regional Spine Institute, our team is trained and experienced in the evaluation, diagnosis, and management of sacroiliac disorders.  We use the latest research and technology to direct both conservative and more complex treatment. When appropriate, our physicians perform fluoroscopically guided diagnostic and therapeutic sacroiliac joint injections.  At Sierra Regional Spine Institute, our goal is to determine and treat the source of a person’s back pain and return them to the road to recovery.

  1. Foley BS, Buschbacher RM.  Sacroiliac joint pain: anatomy, biomechanics, diagnosis, and treatment. Am J Phys Med Rehabil 2006; 85: 997-1006.
  2. Forst SL, Wheeler MT, Fortin JD, Vilensky, JA. The sacroiliac joint: anatomy, physiology, and clinical significance. Pain Physician 2006; 9: 61-68.