Sacroiliac Joint Dysfunction

What is Sacroiliac Joint Dysfunction?

The sacroiliac joint (or "SI joint") is the joint between the sacrum (the bottom vertebrae in the spine) and the pelvis (specifically, the "ilium" bone). It is normally lined with healthy cartilage. Under normal circumstances, it moves very little. However, like other joints in the body, this cartilage can wear thin and become painful. In some circumstances, too much motion in the sacroiliac joint may also be a cause of pain.


The most ​common cause of sacroiliac dysfunction and pain is due to arthritis, or wear and tear of the lower spine. As the cartilage wears out, the bones on either side of the joint may rub against one another, causing pain.

In some patients, the sacroiliac joint may be loose from trauma. The most common cause of this trauma is childbirth, although other accidents may cause the SI joint to become damaged and unstable.


For most patients with Sacroiliac dysfunction, pain is located over the sacroiliac joint. The SI joint is located at the bottom of the back, each about two inches from the middle. This is in the same place as the "dimples" that naturally occur in the lower back (these indentations are the site of the Posterior Superior Iliac Spine, or PSIS). Most patients will notice pain with certain movements that cause motion through the SI joint. Rising from a seated position, bringing your knees to your chest, and getting up from a lying position are some of these movements.


The most important part of the diagnosis is a proper evaluation by a specialist. SI joint problems are often missed by some providers, and overdiagnosed by others, depending on the training they have received. 

  • History: It is important to note what types of activity that make your symptoms worse. Your provider will also learn all previous treatments you have had, and if they have provided any relief.

  • Physical Examination: In addition to a good medical history, a thorough physical examination is the most important part of the diagnosis for any spine-related problem. During the physical examination, there are specific tests that will diagnose and differentiate pain that is coming from the SI joint from other forms of low back pain. This is the most important part of the early diagnosis of SI joint pain is a thorough physical examination.

  • X-rays: X-rays are often the first step for imaging. Even if other images have been taken, x-rays provide unique information that is not available from other studies.

  • MRI: An MRI scanner uses a magnetic field and radio waves that are not harmful to visualize the body in 3D. In most circumstances, it is the best way to see the soft tissues of the body, including nerves, intervertebral discs, and other parts of the spine other than the bones.

  • CT: A CT scan uses many x-rays to produce a 3D image of the body. It is often the best way to visualize any arthritis that may be present in the SI joint, or assess other causes of low back pain.


In most cases, sacroiliac joint dysfunction is not dangerous, but it can be very debilitating and cause pain every day.

  • Physical Therapy: Therapy may be beneficial for patients with instability that can be alleviated with strengthening of specific muscles that stabilize the spine.

  • Injections: The sacroiliac joint is a highly complex joint, and a trained specialist is needed to accurately place an injection into the joint under x-ray. Dr. Bjerke does not do these injections himself, but works closely with trained physiatrists who perform them. Injections are used to treat pain in the SI joint, but are also important in diagnosing the cause of a patient's symptoms and differentiating SI pain from other causes of pain. This is useful information for your provider to pinpoint the cause of symptoms. If you have an injection, it is important to document how the injection affected your symptoms.

  • Sacroiliac Fusion: For patients that have failed other measures, an operation to fuse the SI joint together may provide benefit. This operation eliminates painful motion in the joint and provides lasting relief for many patients. For these patients, Dr. Bjerke performs a minimally-invasive SI Joint Fusion under x-ray, with an accelerated rehabilitation program. For more information, see SI Joint Fusion.

SI Joint: where the spine and pelvis meet