The sacroiliac joint is a strong, weight-bearing linear joint in the lower back at the pelvis joined by dense ligaments in the upper 2/3 of the joint and cartilage in the lower 1/3 of the joint. There is a left and right SI joint that can vary greatly from person to person and can be a source of pain in the lower back and posterior hip. Sacroiliitis refers to inflammation in one or both joints and can be related to abnormal motion occurring in the joints. Typically, these joints become inflamed when the normal symmetry is offset by a leg length discrepancy, limping gait from a lower leg injury, scoliosis, or traumatic fall.
Because the SI joints are located very close to the lower lumbar spine, pain in the lower back and posterior hips can be difficult to diagnose. In fact, SI joints can also cause "sciatica pain" down the leg, mimicking the typical symptoms seen in disc herniations and lumbar nerve root irritation. It rarely causes referred sciatica pain below the knee. Due to the difficulty in diagnosing true SI joint pain, several clinical symptoms and signs are necessary for the diagnosis.
There are several clinical provocative maneuvers that your doctor can perform that may aggravate or reproduce SI joint pain, but there is no one reliable provocative maneuver used to diagnose SI joint pain.
The Gold Standard for diagnosis of SI joint pain or dysfunction is a guided fluoroscopic injection of local anesthetic. Often times, a steroid will be given simultaneously to help alleviate any inflammation within the joint.
Typically this procedure is minimally painful and does not require IV sedation. The patient is placed in prone position lying on their front side. Skin is prepped with either alcohol or betadine. Using fluoroscopy, the affected SI joint is visualized for needle injection. Skin is numbed with lidocaine using a very small needle. A slightly larger needle is then guided under Xray into the joint. Using contrast, placement is confirmed within the joint. A small solution of lidocaine, marcaine, and steroid (Kenalog) is then injected into the joint. In most cases, the patient will report some reproduction of typical pain which can be diagnostic as well. Once the procedure is complete, the patient typically reports some immediate improvement in their pain symptoms.
Patients are generally able to go home immediately following the injection and return to normal activities after about 24 hours of rest from any prolonged standing or strenuous activities. If the SI joint injection proves effective in eliminating the pain, therapy and can be used following the injection to improve mobility and implement home exercises.
The length of relief from SI joint injection varies greatly among patients, but usually provides from 3-6 months relief. As in most cases of lower back pain, obesity and inactivity are indirectly related to long term relief.