What is SI Joint Fusion?

SI joint fusion is surgery that joins, or fuses, the sacroiliac joint. The sacroiliac joint, often called the SI joint, is where the sacrum at the base of the spine meets the ilium bone of the pelvis.

This procedure is also called sacroiliac joint fusion, sacroiliac fusion, SI fusion, or sacroiliac joint arthrodesis. “Arthrodesis” means surgically joining a joint so it moves less or no longer moves.

SI joint fusion may be considered when the sacroiliac joint is strongly suspected to be a major source of chronic pain and non-surgical treatment has not helped enough. It is not a general treatment for all low back pain, hip pain, buttock pain, or leg pain.

De Novo Brain & Spine evaluates adult patients in Stockbridge, Fayetteville, Atlanta, and surrounding communities to help determine whether SI joint fusion, pain management, physical therapy, injections, lumbar spine evaluation, hip evaluation, or another treatment plan may be appropriate.

Conditions This Treatment May Address

SI joint fusion may be considered for selected patients with pain coming from the sacroiliac joint. It is not appropriate unless the SI joint is carefully evaluated as the likely pain source.

Conditions or situations that may lead to consideration of SI joint fusion include:

• Sacroiliac joint dysfunction
• Sacroiliac joint pain
• Sacroiliitis in selected cases
• Degenerative sacroiliitis
• Sacroiliac joint disruption
• Sacroiliac joint instability in selected cases
• Chronic buttock, pelvic, or lower back pain strongly linked to the SI joint
• SI joint pain after prior lumbar fusion in selected cases
• Selected traumatic or structural SI joint problems
• Persistent SI joint pain that has not improved with appropriate non-surgical care

SI joint fusion does not treat lumbar spinal stenosis, herniated disc nerve compression, hip arthritis, generalized arthritis, muscle strain, inflammatory disease, fracture, tumor, infection, or every cause of sciatica-like pain.

When This Treatment May Be Considered

SI joint fusion may be considered when pain has continued despite appropriate non-surgical treatment and the sacroiliac joint has been carefully confirmed as the likely pain generator.

Symptoms may include lower back pain, buttock pain, pain near the back of the pelvis, pain with standing or walking, pain when getting up from a chair, or pain that worsens with certain positions. Some patients may describe pain that overlaps with hip or leg symptoms, which is one reason diagnosis must be careful.

Non-surgical care is usually tried first when there is no urgent structural problem. This may include activity modification, medication, physical therapy, pelvic stabilization exercises, image-guided SI joint injections, radiofrequency ablation in selected cases, and treatment of related lumbar or hip problems when present.

SI joint fusion may be discussed when symptoms, physical examination, imaging review, and diagnostic injection response all support the SI joint as the main pain source. The procedure should not be recommended based on pain location alone.

How Doctors Determine Whether It May Be Appropriate

Doctors determine whether SI joint fusion may be appropriate by comparing the patient’s symptoms, physical examination, imaging findings, response to diagnostic injections, prior treatments, and overall health.

Evaluation may include:

• Medical history and symptom pattern
• Review of prior lumbar spine, hip, pelvic, or trauma history
• Physical examination of the back, pelvis, hips, nerves, gait, and posture
• SI joint provocative maneuvers, such as thigh thrust, compression, distraction, FABER, or Gaenslen testing
• Lumbar spine imaging when nerve compression or spinal disease may be contributing
• Pelvic or SI joint X-rays when arthritis, trauma, or structural disease is suspected
• CT or MRI when infection, tumor, fracture, inflammatory disease, or complex anatomy needs review
• Hip evaluation when hip arthritis or hip pathology may mimic SI joint pain
• Image-guided diagnostic SI joint injection to help confirm the pain source
• Review of prior physical therapy, medications, injections, and other treatments
• Assessment of bone quality, nicotine use, diabetes, infection risk, medications, and surgical risk factors

Diagnosis is often difficult because SI joint pain can overlap with lumbar spine, hip, and pelvic pain. A careful workup helps avoid treating the wrong source of pain.

What the Treatment Involves

SI joint fusion may be performed with a minimally invasive or open approach, depending on the diagnosis, anatomy, surgical plan, and surgeon judgment.

In many minimally invasive procedures, the surgeon reaches the SI joint through small incisions near the pelvis. Implants, screws, rods, bone graft, or other fixation devices may be placed across or near the SI joint to reduce motion and support fusion.

The goal is for the sacrum and ilium to heal together across the treated joint. The exact implant type, surgical approach, imaging guidance, and fixation method depend on the patient’s anatomy, diagnosis, prior surgery, bone quality, and surgeon judgment.

SI joint fusion is not the same as lumbar fusion. It treats the joint between the spine and pelvis, not the lumbar discs or spinal canal.

Goals, Benefits, and Limitations

The main goal of SI joint fusion is to stabilize a painful sacroiliac joint when that joint has been carefully identified as the likely pain source.

Potential benefits may include reduced SI joint motion, improved pelvic stability, and improvement in pain or function when the SI joint is the correct target. Improvement is not guaranteed, and recovery can vary.

SI joint fusion has important limitations. It does not treat every cause of low back pain, hip pain, buttock pain, pelvic pain, or leg pain. It does not decompress nerves, remove a herniated disc, treat spinal stenosis, repair hip arthritis, or correct all pelvic or spinal alignment problems.

General risks may include infection, bleeding, nerve irritation, persistent pain, implant-related problems, failure of fusion, fracture, blood clots, wound problems, need for additional surgery, or pain from another untreated source. Risks depend on the patient’s anatomy, bone quality, medical history, surgical approach, and diagnosis.

Alternatives and Treatment Planning

Treatment planning is individualized. SI joint fusion is one option among several possible treatments for sacroiliac joint pain.

Non-surgical options may include activity modification, medication, physical therapy, pelvic stabilization exercises, weight management when appropriate, SI belt use in selected cases, and image-guided SI joint injections.

Other treatment options may include radiofrequency ablation in selected patients, treatment of lumbar spine disease, hip treatment, pain management, rehabilitation, or continued observation when the diagnosis is uncertain.

Surgical alternatives depend on the underlying problem. If the pain is actually coming from lumbar stenosis, lumbar radiculopathy, hip arthritis, fracture, infection, tumor, or inflammatory disease, SI joint fusion may not be the right treatment.

The best plan depends on identifying the pain source as accurately as possible.

Recovery and Follow-Up

Recovery after SI joint fusion varies from person to person. It depends on the surgical approach, number of joints treated, bone quality, overall health, prior lumbar or pelvic surgery, and whether other pain sources are present.

Follow-up usually focuses on incision healing, pain control, walking, activity progression, neurologic symptoms, medication use, and imaging when needed to monitor implant position or fusion healing.

Patients may need temporary walking assistance, activity restrictions, and physical therapy or rehabilitation guidance. The surgeon will provide instructions about weight-bearing, bending, lifting, driving, wound care, medication use, and return to work or activity.

Persistent or returning pain should be evaluated because symptoms may come from the SI joint, lumbar spine, hip, or another source.

When to Seek Urgent Medical Care

Seek emergency medical care or call 911 for new or worsening leg weakness, loss of bowel or bladder control, numbness in the groin or saddle area, difficulty walking, or sudden severe neurologic changes.

Urgent evaluation is also important for severe back, pelvic, or hip pain after trauma, fever with severe back or pelvic pain, rapidly worsening leg symptoms, or new numbness or weakness that affects standing or walking.

After SI joint fusion, urgent evaluation is important for fever, worsening incision redness or drainage, severe worsening pain, new weakness, leg swelling, chest pain, trouble breathing, or symptoms the surgical team specifically warned about.

Frequently Asked Questions (FAQs):

What is SI joint fusion used for?

SI joint fusion may be used to stabilize the sacroiliac joint when it has been carefully identified as a major source of chronic pain and non-surgical treatment has not helped enough.

Is SI joint fusion the same as lumbar fusion?

No. SI joint fusion treats the sacroiliac joint between the sacrum and pelvis. Lumbar fusion treats spinal levels in the lower back. The procedures address different anatomy and different pain sources.

How do doctors know if pain is coming from the SI joint?

Doctors look at the pain pattern, physical examination, imaging, other possible pain sources, and response to image-guided diagnostic SI joint injection. The diagnosis should not be based on pain location alone.

Does SI joint fusion treat sciatica?

SI joint fusion does not decompress a pinched nerve. Some SI joint pain can mimic sciatica-like symptoms, but true sciatica from lumbar nerve compression usually needs a different evaluation and treatment plan.

Is SI joint fusion always necessary for sacroiliac joint pain?

No. Many patients are treated with non-surgical care first, such as physical therapy, medication, activity modification, and image-guided injections. SI joint fusion may be considered only in selected cases after careful diagnosis.