What Is Sacroiliac (SI) Joint Pain?
SI joint pain usually hurts in the lower back and butt. It can also hurt in the hip, groin, and thigh — often on just one side (though it can be both). Sometimes, SI joint pain can cause your leg to feel weak.
The sacroiliac (SI) joint lies next to the bottom of the spine and absorbs shock. It connects your spine to your hips. You can find your SI joint by feeling for the small dimple just below your waist and above your butt.
Your SI joint can hurt for many reasons. Some of those reasons may relate to the structure of your pelvis.
For example, if your pubic symphysis joint separates after you give birth to a child, it can affect your SI joint. (The pubic symphysis joint connects the two sides of your pelvis.)
SI joint pain is more common than most people know and causes between 15 to 30% of low back pain.
What causes SI joint pain?
There are many causes of SI joint flare ups. Some common causes include:
- A change in your gait or joint motion. For example, knee pain or other types of pain can cause you to walk in a different way.
- Trauma or injury to your lower back. This trauma can be major, such as a car crash, or minor, like improper lifting.
- Pregnancy and childbirth (pregnancy causes the SI joint to loosen).
- Cartilage wears down the joint (degenerative arthritis).
Contact the Department of Physical Medicine and Rehabilitation
Appointments and Referrals
Call 1-412-692-4400 or 1-800-533-8762 to make an appointment with, or refer people to, a doctor from the Department of Physical Medicine and Rehabilitation (PM&R).
What Are the Risk Factors and Complications of SI joint pain?
People of all ages, races, and genders can have SI joint pain.
For younger people, the most common cause is a sports injury or accident. For older people, decline with age causes SI joint pain.
For people designated female at birth, SI joint pain is more common during and after pregnancy.
Other risk factors include:
- Having legs that are different lengths.
- Being older.
- Having inflammatory arthritis.
- Having had spine surgery.
SI joint pain may go away on its own with rest. But it can also get worse and cause more pain. It can make it hard to do daily activities and exercises you love.
This is why it's good to see a doctor to learn the cause of your pain and how to treat it.
How Do I Prevent SI Joint Pain?
SI joint pain can be hard to prevent. It's often not a type of pain people think about until they have it.
Focusing on your posture while sitting may be one way to help prevent SI joint flare ups. Work to keep your weight even among both hips when you sit. Keeping your hips level, versus sitting with one higher than the other, can also help.
Regular exercise can also help prevent SI joint pain. If your joints are strong, you're less likely to injure them.