Low back pain and leg pain can be caused by dysfunction of the sacroiliac joint. The sacroiliac joint is considered the “chameleon” of the spine. It is composed of a connection of the sacrum and iliac bones. The dysfunction is caused by worn cartilage between the joints which causes pain when the bones rub together. Dysfunction in the sacroiliac joint can mimic lumbar disc, nerve root and facet joint pain. These conditions are associated with lumbar structures other than the sacroiliac joints. There might also be an inflammatory process involved in the condition.
The symptoms of SI dysfunction include low back pain and pain in the buttocks which often radiates to the leg. The pain is normally located above the knees but it is not uncommon for it to extend to the ankle and foot. SI dysfunction can occur during pregnancy when the hormone relaxin causes ligaments to relax which decreases the structural support of the sacrum and iliac bones.
The diagnostic test requires a sacroiliac joint injection (block) by an experienced physician. It involves the insertion of a needle into the sacroiliac joint. This requires good skill and precision. A local anesthetic medication like lidocaine is injected in the spine to numb the area. Pain relief from this injection helps to confirm the source of the pain, which is the sacroiliac joint. This is followed by a therapeutic injection of steroid and local anesthetics by a spinal needle.
Non- operative treatments include anti-inflammatory medications and steroid to reduce inflammation and pain. Physical therapy is beneficial which strengthens the muscles, this increases structural support. Surgical intervention is also an option if the pain persists after initial interventions. Surgery includes fusion of the joints.