What Is the Sacroiliac Joint?

The sacroiliac (SI) joint connects the triangular bone at the bottom of the spine (sacrum) to a part of the pelvis known as the iliac bone. Though the SI joint isn’t flexible, it is strong and stable, transferring the forces of the upper body to the pelvis and legs.

Because of its importance in the skeletal system and its shock-absorbing nature, the SI joint can be prone to wear and tear. Symptoms that present when there is an issue with the SI joint may include pain that begins in the thigh and/or buttock, then radiates down the leg.

What Causes Sacroiliac Joint Pain?

The cause of SI joint pain is typically due to SI joint dysfunction. SI joint dysfunction can be the result of too much movement (hypermobility) or too little movement (hypomobility) of the joint. Generally, it is more common in young and middle-aged women.

In some cases, the pain may be due to sacroiliitis, a term used to describe any type of inflammation in the SI joint. This pain can be observed after trauma, pregnancy (with expansion of the pelvis) or after spinal fusion surgery.

Sacroiliitis is often an aspect of an inflammatory condition affecting the spinal column. Conditions include:

  • Ankylosing spondylitis, an inflammatory disease that can cause spinal vertebrae to fuse together
  • Psoriatic arthritis, a type of arthritis that affects patients living with the skin condition psoriasis
  • Reactive arthritis, joint pain and swelling that is triggered by an infection in a different part of the body (most commonly the genitals, gastrointestinal or urinary tract)

When Is Sacroiliac Joint Fusion Necessary?

SI joint fusion may be recommended if patients have persistent symptoms and all other treatment modalities have failed, such as physical therapy, injections or medications. Patients may also be offered SI joint fusion after having positive relief from one to two SI joint injections from an interventional pain physician.

In most cases, SI joint fusion surgery is minimally invasive and performed through a small incision. This approach usually allows patients to have a shorter hospital stay (patients generally go home the same day as the surgery), shorter recovery time and a reduced risk of complications.

Different methods include:

  • iFuse Implant System®, which inserts titanium implants to permanently fixate the joint
  • SI-LOK® Fixation System, which implants screws to hold the joint in place and reduces painful movement
  • SImmetry® System, which removes cartilage in target areas to promote healing, places bone graft material over the joint, then fixes the joint in place with screws and plates

Meet the Fusion Specialists

At IGEA Brain & Spine, our surgeons specialize in only the most advanced techniques for SI joint fusion. In doing so, we are able to improve quality of life for patients living with these and other painful conditions of the spine, as well as the brain and neuroendovascular system.

For more information on SI joint fusion or to schedule an appointment with one of our specialists, contact us today.

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