The sacroiliac joint is the joint which connects the spine to the pelvis. This key joint in the body actually comes in the form of a pair of joints which function together, the left and right sacroiliac joints. Sometimes called the SI joint, this joint can be subject to a variety of medical issues which can cause discomfort, pain, and difficulty walking in people of all ages. Older people tend to be more at risk of SI joint dysfunction.
This joint connects the sacrum at the end of the spine with the pelvis. Small dimples at the base of the lower back correspond with the location of the sacroiliac joint. The joint serves several different functions in the body. One function is to act as a shock absorber for the spine, distributing the shock of walking across the pelvis to reduce the strain on the spine. This joint also stabilizes the body during walking, working in concert with the pelvis so that people can walk and run upright.
Another function of this joint is to convert and carry twisting movements. Torsion would cause the pelvis to crack and split, which is not desired, and this joint is designed to twist while keeping the pelvis stable and intact. At the area of the joint, the bones have rough surfaces which interlock, and the joint is stabilized and supported by a network of ligaments which are designed to keep the joint in place.
Sacroiliitis is an inflammation of the sacroiliac joint. Sacroiliac inflammation can happen for a number of reasons including physical strain, infections, spinal arthritis, and so forth. Patients with this condition feel pain and stiffness around the pelvis and lower back. SI joint dysfunction, a related condition, occurs sometimes during pregnancy as a result of hormones which soften the joint, and can occur as a result of damage to the ligaments as well. In both cases, patients may find it difficult to move, and may experience pain with movement of the pelvis.
When joint pain and other problems are identified in the sacroiliac joint, medical imaging studies and other diagnostic tests may be used to learn more about the cause of the pain. These studies provide information about the site of the dysfunction so that a doctor can determine which treatments might be most appropriate. Treatments can include medications, surgery, physical therapy, massage, and a variety of other tools which are intended to restore comfort and a free range of motion to the joint.