For about 15-30% of patients with chronic lower back pain, the cause is the sacroiliac (SI) joint. However, most physicians are not trained to consider the SI joint when evaluating lower back pain.
Dysfunction in the sacroiliac (SI) joint can cause lower leg and/or back pain. Clinical publications have identified the SI joint as a pain generator in 15-30% of patients with chronic lower back pain.
Leg pain from SI joint dysfunction can be particularly difficult to differentiate from radiating leg pain, which is sometimes caused by a lumbar disc herniation (sciatica).
As the diagram shows, the sacrum attaches to the large pelvic bones known as the ilia. The joints that connect the sacrum to the ilia are called the sacroiliac (SI) joints. These joints transfer weight and forces between your upper body and legs.
SI joint degeneration can be a result of degenerative disease, trauma, pregnancy/childbirth, prior lumbar fusion and other causes. Injury to the ligaments, muscles or other soft tissues supporting the SI joint is known as SI disruption, which can alter the joint’s ability to change to new positions and/or transfer load during routine physical activities.
Symptoms of SI joint degeneration or disruption include pain, feelings of numbness, or weakness/tingling in the lower back, buttock and/or legs. Symptoms may resemble those of other spine conditions, such as a herniated disc or a compressed nerve root.