“Sacro… what?” is probably the response you would hear from most people if asked about sacroiliac joints (SI). You may never have heard of them before, but the SI joints play vital roles in both body stability and move­ment. These large synovial joints of the pelvis join the triangular bone at the bottom of the spine (the sacrum) to the two big pelvic bones (the ilia) on either side.

Although these are crucial weight-bearing joints important for their part in the stability of the pelvis, they also move slightly for proper mechanics when walking or running. The SI joints can be affected by overex­ertion and injury. Your chiropractor is well-acquainted with the functional anatomy of these joints and will often adjust the SI joint to alleviate pain.

For patients with lower back or buttock pain that stems from the sacroiliac joint, a variety of chiropractic procedures can be applied and are often considered the first line of treatment.

The chiropractic treatment goal for sacroiliac joint pain is to utilize a method that is best tolerated by the patient and yields the best outcome. Patients respond better to different approaches, so the chiropractor may adopt various manipulations to treat the patient’s sacroiliac joint pain.

At the lower end of the spine, just below the lumbar spine lies the sacrum. The sacrum is a triangular shaped bone that is actually formed by the fusion of several vertebrae during development. The sacroiliac (SI) joint sits between the sacrum and the iliac bone (thus the name “sacroiliac” joint). You can see these joints from the outside as two small dimples on each side of the lower back at the belt line.

The SI joint is one of the larger joints in the body. The surface of the joint is wavy and fits together similar to the way Legos® fit together. Very little motion occurs in the SI joint. The motion that does occur is a combination of sliding, tilting and rotation. The most the joint moves in sliding is probably only a couple of millimeters, and may tilt and rotate two or three degrees.

The SI joint is held together by several large, very strong ligaments . The strongest ligaments are in the back of the joint outside of the pelvis. Because the pelvis is a ring, these ligaments work somewhat like the hoops that hold a barrel together. If these ligaments are torn, the pelvis can become unstable. This sometimes happens when a fracture of the pelvis occurs and the ligaments are damaged. Generally, these ligaments are so strong that they are not completely torn with the usual injury to the SI joint.

Here is a lesson from Dr. Dana O’Neil!