The lower part of the sacroiliac joint can be a source of pain due to arthritis or chronic strain. Symptoms, physical examination, and imaging studiesare not reliable indicators of sacroiliac pain. Diagnostic injectionis the only definitive way to make the diagnosis. The joint can be injected by inserting a thin needle under x-ray guidance into the joint space. A small amount of contrast material is then injected to prove that the needle is really in the joint, and then a mixture of local anesthetic and corticosteroid is injected. The anesthetic numbs the joint and relieves the pain if the joint is the pain generator. The steroid reduces inflammation in the joint to give longer lasting relief and to allow participation in a physical therapy program. This is just like injecting a knee or shoulder.

A negative injection does not entirely rule out the joint as a source of pain. The injection only affects the lower part of the joint which is a true joint. The upper part is held together by many ligaments which may be strained and a source of pain. Local injections into the ligaments may be helpful.