If you don’t know the source of your lower back pain, consider your sacroiliac (SI) joint a possible suspect. Even though many people have never heard of it, estimates say that dysfunction of the SI joint is responsible for 15% to 30% of lower back pain cases.1
What is an SI joint?
The SI joint is where your pelvis connects to the bottom of your spine (sacrum). You have one of these joints on each side.
SI joints are sturdy and withstand tremendous pressure. They support the weight of your upper body, acting as shock absorbers when energy transfers between your upper body and your pelvis and legs. These joints also support your range of motion when you bend at the hips or twist.
Every time you get up from a seat or walk upstairs, you’re putting stress on your SI joints. Daily activities wear down these joints over time. If the joints move too much (or too little), it can lead to pain.
What SI joint pain feels like
SI joint problems can be characterized by these symptoms:
- Dull, aching pain on one side of your lower back.
- Lower back pain that worsens with certain movements, such as getting in and out of a car, bending down, and getting out of bed in the morning.
- Pain that radiates down behind your upper leg, similar to sciatica.
- Pain that feels like it’s coming from your hips.
Pain caused by SI joint dysfunction can occur on both sides of your body, even though it’s more common to have pain on just one side.
Another fact to keep in mind: SI Joint dysfunction is more common in young and middle-aged women. Women who are pregnant or have recently given birth may be more susceptible to SI joint pain.2
What SI joint pain doesn’t feel like
Pain caused by SI joint dysfunction doesn’t commonly show these characteristics:
- Pain that radiates down the leg below the knee.
- Weakness or numbness in your lower body.
If you exhibit these symptoms, your SI joint is not likely the source of pain.
How to check for SI joint dysfunction
It is recommended you visit a health care provider, such as an osteopath, physical therapist, or physiatrist, to see if you have SI joint dysfunction. Typically they apply gentle pressure using various techniques. These tests may include:
- Sacral thrust test. Pressure is applied to the back of your hips while you lie face down on a table.
- Distraction test. Pressure is applied to the front of your hips while you lie face up on a table.
- FABER test. You lie on your back with one leg straight and the other leg bent, its ankle resting on your straight leg’s thigh. (In this position, your body may look like a figure “4.”) Pressure is applied by gently pushing your bent knee down and out.
If these tests reproduce your pain, it may signal SI joint dysfunction.
A doctor may also give your SI joint a local anesthetic injection. If the injection alleviates your pain, your SI joint may be the problem.
SI joint dysfunction can’t be pinpointed by imaging diagnostics, such as an x-ray or MRI. However, these tests can check for other possible causes of pain.
If your lower back and/or legs are in severe pain, you should visit a health care provider immediately.
- Cohen SP, Chen Y, Neufeld NJ. Sacroiliac joint pain: a comprehensive review of epidemiology, diagnosis and treatment. Expert Rev Neurother. 2013 Jan; 13(1):99-116.
- McGrath C. Clinical considerations of sacroiliac joint anatomy: a review of function, motion and pain. Journal Osteopathic Medicine. 2004; 7(1):16-24