The sacroiliac joint (SI joint) is where the bones of the spine connect to the pelvis. There is one joint on the right side and one on the left. These joints are held together with strong bands of fiber called ligaments.

The SI joint has little movement. Its main job is to decrease impact to the spine during activities like walking. Problems in this area can cause pain in the lower back which may also pass into the groin or down the legs.

Sacroiliac Joint
sacroiliac joint
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Damage to bones or ligaments of the joint can cause inflammation. The inflammation can cause pain and irritate nearby nerves. This leads to more pain. Inflammation of the joint may be caused by:

  • Problems in the bones of the joint such as:
  • Injuries to the ligaments from:
    • Regular high impact activities such as jogging
    • Trauma such as an car crash or fall
    • Falling or taking awkward steps off a curb or step
  • Changes during pregnancy—may allow for more movement of the joint which can cause irritation

Risk Factors

SI joint pain may be more likely to happen with:

  • Weak muscles
  • Bending or twisting the back
  • Improper lifting
  • Inflammatory conditions, such as ankylosing spondylitis or psoriatic arthritis
  • High impact sports or activities
  • Trauma


SI joint pain will differ based on the exact cause of the pain. The pain may be dull or sharp and may be any of the following:

  • Mild-to-severe low back pain
  • Pain in the buttocks
  • Pain that seems deep in the pelvis
  • Pain in the hip or groin or back of the thigh
  • Pain that radiates down the leg on the affected side
  • Stiffness of the lower spine

Pain may increase with certain activities such as walking, twisting, rising to stand, or bending


You will be asked about your symptoms and medical history. A physical exam will be done.

The doctor will most likely make a diagnosis based on your symptoms. If there are other more serious symptoms or severe pain your doctor want to take images of the area. This can be done with:

If needed, the doctor may use a nerve block to make sure the pain is coming from the SI joint. Medicine that blocks pain is injected near the SI joint. If pain stops, then the joint is confirmed as the cause.


Treatment depends on the cause of the pain. Any underlying condition would receive treatment specific for that disease. For all causes, short-term rest is often the first step to allow time for the joint to heal.

Talk with your doctor about the best treatment plan for you. Options may include one or more of the following:


Medicine can help manage inflammation and reduce pain while the joint heals. Options include:

  • Over-the-counter pain relievers, such as acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Prescription pain relievers
  • Muscle relaxers—to decrease tension in the area which can make pain and injury worse
  • Steroid injections into the sacroiliac joint—to decrease inflammation

Physical Therapy

The joint may be moving too much or too little. An imbalance of muscles around the joint can also cause more problems. Physical therapy may help to speed healing and find a cause. Therapy sessions may include:

  • Exercises to stretch or strengthen the muscles of the lower back
  • Exercises to improve the motion of the sacroiliac joint
  • Ice or heat therapy


Decreasing stress on the back will lower the chance of SI joint pain. Healthy steps include:

  • Exercising regularly to keep muscles strong
  • Maintaining good posture
  • Using proper techniques for bending, lifting, or playing sports

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