Overview
The sacroiliac (SI) joints connect the base of the spine (sacrum) to the pelvis. When these joints move too much or too little, or become inflamed, they can cause pain in the low back, buttock and sometimes the leg.
SI joint pain can be hard to tell apart from other causes of back pain. A diagnostic injection can help confirm it. Treatment ranges from therapy and belts to injections and minimally invasive SI joint fusion.
Watch: SI Joint Dysfunction explained
Video: “SI Joint - Where is it and how does it work?” from SI-BONE on YouTube. It loads from youtube-nocookie.com only when you press play. Shown for general education; GSMC did not produce it. Watch on YouTube
Common symptoms
- Pain in the low back or buttock, usually on one side
- Pain that may spread to the groin or thigh
- Pain with sitting, climbing stairs or rising from a chair
- Pain when lying on the affected side
Causes and risk factors
- Arthritis
- Pregnancy and childbirth
- Prior lumbar fusion
- Injury or fall
- Inflammatory conditions
How it is diagnosed
Diagnosis combines your history, specific physical exam tests and, often, an image-guided diagnostic SI joint injection. Imaging helps rule out other causes.
Treatment options
Care usually starts with conservative steps, such as activity guidance, physical therapy and medication. Procedures are considered when those steps do not give enough relief. Which options fit you depends on your exam, imaging and goals.
When to seek urgent care
Call 911 or go to the emergency department for new or rapidly worsening weakness, numbness in the groin or inner thighs, loss of bladder or bowel control, severe pain after a significant fall or accident, or pain with fever or unexplained weight loss.
Frequently asked questions
How common is SI joint pain?
The SI joint is thought to be a source of pain in a meaningful share of people with chronic low back pain.
How is it confirmed?
Physical exam maneuvers plus a diagnostic injection that numbs the joint are commonly used.
What is SI joint fusion?
A minimally invasive procedure that places implants across the joint to stabilize it, for selected patients whose pain has not improved with conservative care.
This page is general patient education and does not replace advice from your own clinician. Individual results vary.