Sacroiliac Joint Fusion

Sacroiliac Joint (SI Joint) Anatomy

The sacroiliac joint or SI joint (SIJ) is the joint in the lower portion of the spine. It is located in the bony pelvis between the sacrum and the ilium of the pelvis, which are joined by strong ligaments. The sacrum supports the spine. The sacrum is supported by an ilium on each side. The pelvis is held together by a series of ligaments and muscles and the SI Joint acts as a shock absorber, transmitting the body’s load from the upper body to the legs.

SI Joint Anatomy


What causes sacroiliac joint pain?

Sacroiliac joint pain can be categorized as pain from the leg, buttocks, groin, and lower spine. Normal wear and tear of the joint (degenerative), traumatic events, and inflammation can lead to painful walking, sitting, sleeping, getting in and out of a car, and other activities. Although it is not always clear what causes sacroiliac joint pain, it is estimated that 15%-25% of patients with axial low back pain can attribute their pain to the SI Joint.1

After reviewing your medical history, x-rays, and the results of other tests you have completed, your doctor may recommended that you consider surgery using Rialto SI Fusion System.

  1. Cohen, Steven P. Sacroiliac Joint Pain: A Comprehensive Review of Anatomy, Diagnosis, and Treatment. Anesth Analg 2005; 101:1440-1453.
Conditions Associated with Sacroiliac Join Pain

What is Sacroiliac Joint Disease

Sacroiliac Joint Disease typically comes from one of two conditions:

Degenerative 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 Disruption - This condition generally refers to abnormal motion in the sacroiliac joint, either too much motion or too little motion.

Why may I need surgery?

You may be a candidate for surgery if you have tried, with no lasting relief, other conservative care options such as physical therapy, chiropractic, medications, and/or injections for at least 6 months. After consulting with your surgeon, it may be determined that surgery might be an option to limit the amount of movement of the SI Joint in an effort to treat your diagnosis.

What is the RialtoTM SI Fusion System?

The Rialto SI Fusion System is intended to stabilize your sacroiliac joint and provide an environment for fusion (joining bones together into one solid structure) to occur.

Rialto SI Fusion System

The Rialto SI fusion system consists of cylindrical threaded devices designed to enhance sacroiliac joint fusion. The threaded devices are offered in various lengths to accommodate your anatomy. For fusion of the SI joint, one, two, or three devices may be placed at your surgeon’s discretion.

Benefits of SI Joint Fusion

SI joint fusion with the Rialto SI fusion system has several advantages:

How is the surgery performed?

The Rialto SI Fusion procedure is performed under general anesthesia, in a minimally invasive fashion.

  1. Your surgeon will make a small incision above the buttock, just below your waist. The incision will be slightly to the left or right of your spine, depending on the area to be treated.
  2. Through a series of steps, a cylindrical threaded device will be placed and packed with autograft and/or allograft to promote bone growth.
  3. Typically, but not always, two devices are placed to provide stability and promote fusion.
Posterior vs. Lateral Approach

Most SI fusion devices require the surgeon to perform the procedure from the side of your body, using a lateral approach. The Rialto SI fusion system uses a posterior approach to the SI joint, which means the surgeon enters from your back side.

Watch this presentation to see the difference between a posterior and lateral approach to the SI joint.

Advantages of the posterior approach used with the Rialto SI fusion system include:

If you are experiencing symptoms and feel you may benefit from SI fusion please contact NeoSpine today to set up a consultation with a qualified surgeon.

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