How Sacroiliac Joint Fusion is Performed

In a sacroiliac joint fusion, one or both sides of the sacrum is grafted to the ilium to encourage bone growth across the joint. Fusion occurs during the healing process following the surgery, and is achieved using implanted instrumentation and/or a bone graft.

The most common method of sacroiliac joint fusion is a minimally-invasive procedure, performed through a small incision in the buttock. Open sacroiliac joint fusion is rarely used due to extensive healing processes and higher complication rates.

Minimally-Invasive SI Joint Fusion Procedure

Implant systems for SI joint fusion have been developed in recent years that allow the procedure to be minimally invasive. The most commonly used systems have been shown to relieve excessive motion at the joint through fusion, minimizing pelvic and lower back pain. Additionally, these systems have been shown to cause fewer complications and require a less-extensive recovery process than open fusion surgeries.¹Kube RA, Muir JM. Sacroiliac Joint Fusion: One Year Clinical and Radiographic Results Following Minimally Invasive Sacroiliac Joint Fusion Surgery. Open Orthop J. 2016;10:679-689.^,2Ledonio CG, Polly DW, Swiontkowski MF, Cummings JT. Comparative effectiveness of open versus minimally invasive sacroiliac joint fusion. Med Devices (Auckl). 2014;7:187-93.

A typical SI Joint fusion procedure typically consists of the following basic steps:

1. The patient lays prone (face down) on the operating table under general anesthesia.
2. A small incision, usually ranging from 2 to 3 centimeters, is made in the side of the buttock and the gluteal muscles are dissected to access the ilium.
3. A small guide pin is inserted through the side of the ilium to create a small hole allowing access to the ilium. This opening is then broached or drilled through the ilium to provide passage for the implants to reach the sacrum.
4. If a bone graft is necessary, the SI joint is cleared of cartilage and soft tissues, and a bone graft is packed into the joint space. The bone graft is typically collected from a different area of the ilium or from shavings left behind from broaching the ilium.
5. The implant instruments are guided through the passage in the ilium, and are put into place using screws, pins, or a mallet.
6. The incision site is then irrigated using a saline solution, which removes any debris from the wound before it is closed. Then, the incision is closed in layers using standard sutures.

Minimally-invasive fusion surgeries typically last about an hour and pose a low risk of complications during the procedure. Throughout the surgery, fluoroscopic imaging is used to appropriately implant instruments and prepare the sacroiliac joint.

In addition, minimally-invasive procedures have been shown to improve disability scores and pain reduction following surgery more than open SI joint fusion.²Ledonio CG, Polly DW, Swiontkowski MF, Cummings JT. Comparative effectiveness of open versus minimally invasive sacroiliac joint fusion. Med Devices (Auckl). 2014;7:187-93.

Open SI Joint Fusion: A Rarely Used Procedure

Open surgery, which is done without the use of minimally invasive technology, is now rarely performed, as the minimally invasive approach has fewer complications and quicker recovery time.

A study that compared minimally-invasive techniques with an open procedure found that both surgeries caused significant clinical improvement for patients in terms of pain scores and disability, with minimally-invasive surgery patients experiencing greater improvements in all measures.²Ledonio CG, Polly DW, Swiontkowski MF, Cummings JT. Comparative effectiveness of open versus minimally invasive sacroiliac joint fusion. Med Devices (Auckl). 2014;7:187-93.