The Sacroiliac joint is a large fluid filled joint formed by the junction of the sacrum and ileum. The joint allows a small amount of rotation and forward and backward movement. The greatest amount of movement occurs when individuals rise from a sitting or lying position to standing position. In middle age and beyond, fibrous adhesions (scar tissue) and degenerative changes result in gradual loss of the synovial cavity which occurs in both sexes. This occurs earlier in men, and after menopause in women. The joint can dysfunction as a result of injury, abnormal weight bearing, leg length discrepancies, fractures, changes in walking patterns, pregnancy, and a host of other arthritic disorders. Pain can also be referred to the area by the lumbar discs.
To diagnose pain from the sacroiliac joint, a physical exam can be helpful, but it is not always reliable.