Your Sacroiliac Joints (SIJ) are a critical linkage system between your lower spine and pelvis. The sacrum (tailbone) connects on the right and left sides of the ilia (pelvic bones) to form your sacroiliac joints.
Your sacroiliac joints should be a fairly stiff or rigid link between the pelvic bones, and allow only a few degrees of movement. In some people due to trauma or just extra mobility, your sacroiliac joints have too much uncontrolled motion. This allows your sacroiliac joints to adopt an abnormal or stressed joint position, which may result in SIJ pain.
When your sacroiliac joints are not moving normally due to either stiffness or excessive movement, it is referred to as Sacroiliac Joint Dysfunction, which normally results in sacroiliac pain.
It is vital that you have both normal SIJ movement and muscle control around this area to avoid SIJ pain and injury.
Commonly sacroiliac dysfunction can cause lower back, hip, buttock and sciatic pain.

Sources of Sacroiliac Joint Dysfunction
The primary mechanisms of SI joint dysfunction include:
How do health care professionals diagnose sacroiliac joint dysfunction?
The first step in diagnosis is typically a thorough history and physical examination by a physician. The physician will ask questions to determine if there are any underlying disorders that could be causing the patient’s pain. Certain signs can also help differentiate pain coming from the SI joints, lumbar spine, or hips. There are various tests a physician can perform during the physical examination that can help isolate the source of the pain. By placing the patient’s hips and legs in certain positions and applying pressure, the SI joints can be moved or compressed to identify them as a source of pain. Other portions of the examination are to exclude certain possibilities that could mimic sacroiliac disease.