In the first part of the 20th century, sacroiliac (sack-row-ill-e-ack) (SI) joint syndrome was the most common diagnosis for lumbago (lom-bay-go) (low back pain). Any pain in the low back, buttock, or leg was usually referred to as SI joint syndrome. Before 1932, SI joint syndrome was a very popular diagnosis. There was actually a period referred to as the “Era of the SI Joint.”
In the late 1980s, many doctors “rediscovered” the SI joints as a possible source of back pain. Yet even today, SI joint pain is often overlooked. Many doctors have not been trained to consider it. Many are still reluctant to believe a joint that has so little movement can cause back pain.
Many problems can cause degenerative arthritis of the SI joints. It is often hard to tell exactly what caused the wear and tear to the joints. One of the most common causes is an injury. The injury can come from a direct fall on the buttocks, a motor vehicle accident, or even a blow to the side of your pelvis. The force from these injuries can strain the ligaments around the joint. Ligaments are the tough bands of connective tissue that hold joints together. Tearing of these ligaments can lead to too much motion in the joint. The excess motion can lead to wear and tear of the joint and pain from degenerative arthritis. Injuries can also cause direct injury of the cartilage lining the surfaces of the joint where motion occurs. Over time, this will also lead to degenerative arthritis in the joint.
Pain can also be caused by an abnormality of the sacrum bone. The sacrum bone is actually a very specialized set of vertebrae. When your body is undergoing development in the womb, several vertebrae fuse together to form the sacrum. In some people the bones that make up the sacrum never fuse together. In these cases, two or more of the vertebra that should fuse together remain separated. This creates an odd situation where the SI joint is not formed properly and a false joint occurs (sometimes called a “transitional syndrome”). This abnormality can be seen on X-rays. People who have this syndrome seem to have more problems with their SI joints, as well as back pain that appears to come from that area.
Women are at special risk for developing SI joint problems later in life due to childbirth. Female hormones are released during pregnancy that allow the connective tissues in the body to relax. The relaxation is needed so the pelvis can stretch enough to allow the baby to be born. This stretching causes changes to the SI joints, making them extra or overly mobile. Over a period of years these changes can lead to wear-and-tear arthritis. During pregnancy, the SI joints can cause discomfort both from the effects of the hormones that loosen them and from the stress of the growing baby. The more pregnancies a woman has, the more chance she has of developing SI joint problems.
Symptoms of SI joint syndrome are often hard to distinguish from other types of low back pain. In most cases, there is a confusing pattern of back and pelvic pain that mimic each other, making diagnosis of SI joint syndrome very difficult. The most common symptoms of SI joint syndrome include: