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Sacro-Illiac (SI) Joint Fusion

Sacro-Illiac (SI) Joint Fusion

The sacroiliac joint, or SI joint, is a large joint in the pelvis that connects the sacrum and the ilium of the pelvis. This joint is a strong, weight bearing, ligament lined joint on both sides of the pelvis. These joints are supposed to move together as single unit. Just like other joints in the body, this joint has strong internal and external ligaments. The SI joints’ function is additional for shock absorption for the spine. As we age, the joint’s stability can change as ligaments become loose and the joint surfaces lose their original orientation.


Sacroiliac joint pain is often from dysfunction from one of the two joints. When one joint does not move properly pain may be felt as one-sided low back pain or midline “tailbone” sacral area pain. The joint can move too much (hypermobility) or too little (hypomobility) and can feel tight and “locked-up”. Pain can be dull or very sharp with certain movements. When SI joint dysfunction is severe, this joint can refer pain to the hip, groin, buttocks, and even down the back of the thigh. Pain may be worse with movements that stress that joint, such as standing up from a seated position, walking up an incline, and prolonged sitting or walking. This pain can be similar to pain experienced with degenerative hip disease, hip bursitis, lumbar disc herniation, or lumbar radiculitis. This joint can also become inflamed called sacroiliitis.

Sacroiliac Joint Fusion

Sacroiliac (SI) joint fusion is a technique used to stabilize the sacroiliac joint. This is generally used to treat back or leg pain caused by SI joint dysfunction. Approximately 15% mof lumbnar pain is thought to be due to SI joint pain. The majority of patients can be treated non-operatively through anti-inflammatory medications, physical therapy, or SI joint injections. However, some patients will require surgical treatment when conservative therapies have failed to improve symptoms.

Numerous techniques exist for the surgical treatment of sacroiliac joint dysfunction, the primary goal being to stabilize the joint by using implants and sometimes instrumentation.

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