The two sacroiliac joints connect your pelvis with your lower back. Sacroiliac joint dysfunction, also called SI joint pain or SI joint dysfunction, is an injury to a sacroiliac joint. It usually affects only one side of the body.

Sacroiliac joint dysfunction causes pain in the low back and/or the leg. The pain can make it hard to do things like sitting, walking, or climbing stairs.

Car accidents or falls are the most common cause of sacroiliac joint dysfunction. Diagnosis can be difficult, since the pain may seem like other causes of low back and/or leg pain.

Symptoms of Sacroiliac Joint Dysfunction

Pain is the most common symptom of sacroiliac joint dysfunction. The pain is usually in the lower back and butt. Sometimes, it’s in the back and upper leg.

Other symptoms are:

  • Feeling uncomfortable when bending over or standing after sitting for a long time
  • Improvement in pain when lying down