SI Joint Fusion (Sacroiliac Arthrodesis)

What is SI joint fusion (arthrodesis)?

Sacroiliac (SI) joint fusion, or arthrodesis, is a minimally invasive procedure that stabilizes a painful, dysfunctional SI joint so the two sides of the joint grow solidly together. The sacroiliac joints sit where the base of the spine (sacrum) meets the pelvis (ilium), and when one becomes a pain generator it can cause stubborn low back, buttock, or hip pain. Dr. Eaddy uses a lateral (transiliac) approach, placing two threaded titanium implants across the joint under X-ray guidance.

Who is a candidate?

Candidates have chronic sacroiliac joint dysfunction — pain that has not responded to activity modification, physical therapy, medication, and SI joint injections. Because many conditions cause pain in this region, an accurate diagnosis comes first: a focused examination and diagnostic SI joint injections that reproduce and then temporarily relieve your pain help confirm the SI joint is the true source before fusion is considered.

How is the procedure done?

SI joint fusion is performed through a small incision on the side of the buttock — a lateral, transiliac approach. Guided by live X-ray, Dr. Eaddy places two threaded titanium implants across the joint, from the ilium into the sacrum, to stabilize it and allow the bone to fuse. Compared with traditional open fusion, this minimally invasive, outpatient technique uses a much smaller incision and disrupts far less muscle and tissue.

What is recovery like?

Most patients go home the same day and walk with assistance soon after. Weight-bearing on the treated side is often limited for a few weeks to protect the fusion, followed by physical therapy. The joint continues to fuse over several months as bone grows across it, and Dr. Eaddy will give you activity guidance specific to your case.

What are the risks?

SI joint fusion is minimally invasive and generally well tolerated, but as with any implant procedure there are risks, including:

• Infection
• Bleeding
• Nerve irritation or injury
• Implant malposition or loosening that may require revision
• Failure of the joint to fully fuse
• Continued or recurrent pain

Reducing the risk of infection before your procedure

Because a device is implanted, Dr. Eaddy uses a skin-preparation protocol in the days before your procedure to lower the already-small risk of infection. Follow the exact instructions the office gives you — in general it involves:

• Mupirocin antibiotic ointment — applied twice daily for the five days leading up to your procedure.
• Hibiclens (chlorhexidine gluconate) antiseptic wash — used each day for the four days before your procedure, and once more on the morning of the procedure.

This reflects published evidence that decolonizing the skin and nose with mupirocin and chlorhexidine (Hibiclens) lowers the rate of surgical-site infection. See preparing for an interventional pain procedure for the rest of your pre-procedure checklist.

Trusted resources

Learn more from these independent medical sources:

• North American Spine Society — Know Your Back
• Whang et al. — SI joint fusion vs. non-surgical management: randomized controlled trial (Int J Spine Surg, 2015)
• Dengler et al. — Minimally invasive SI joint fusion vs. conservative management: randomized controlled trial (Pain Physician, 2017)

Related care

Conditions and treatments connected to this page, all provided by Dr. Eaddy:

• Back Pain — diagnosis and treatment for acute and chronic low back pain
• Sciatica — radiating leg pain from a compressed nerve root
• Radiofrequency Ablation — longer-lasting relief for facet and sacroiliac joint pain
• Failed Back Surgery Syndrome — persistent pain after spine surgery
• Patient guide: preparing for an interventional pain procedure — blood thinners, drivers, skin prep, and more

Reviewed by Kenneth J. Eaddy, MD · Updated July 2026