Sacroiliac joint dysfunction can result in pain in the low back and/or buttocks. Pain may also radiate down one or both legs or spread to surrounding muscles that may spasm in response to joint dysfunction.
The symptoms of SI joint dysfunction can mimic many other causes of lower back pain, such as a lumbar herniated disc, osteoarthritis, or lumbar degenerative disc disease. Getting an accurate diagnosis is the essential first step in finding appropriate treatment and pain relief.
The SI joints are located at the bottom of the spine. In the image above they are highlighted in purple.
What are the sacroiliac (SI) joints?
The sacroiliac joints connect your hip bones to the sacrum at the very bottom of your spine. These joints are designed to provide a great deal of strength and stability.
You probably have not thought about your sacroiliac joints. They are not an obvious joint, like an elbow or knee, but they work hard throughout the day to enable and coordinate the transfer of weight from the upper body to the lower body.
The sacroiliac joints connect the pelvic bone to the sacrum. They are designed to allow a minimal amount of movement and are reinforced with an interconnected network of strong ligaments and tendons.
How does sacroiliac joint dysfunction develop?
Sacroiliac joint dysfunction can develop if the SI joint(s) move either too much or too little.
Pregnancy or injury to the ligaments, among other things, can cause too much movement to occur in the sacroiliac joints. This is known as hypermobility.
Too little movement in the joints, referred to as hypomobility, can also cause pain. Hypomobility may occur as a result of a degenerative joint disease such as arthritis.
Read more about Osteoarthritis of the Spine
Sometimes the sacroiliac joints overcompensate for problems in nearby joints and may become painful. For example, it is possible for someone who has had a lumbar spinal fusion surgery to develop sacroiliac joint pain due to reduced motion in the fused lumbar spine segments.