Sacroiliac (SI) joint blocks are injections that treat low-back pain associated with sacroiliac joint dysfunction.

The SI joint lies next to the spine and connects the sacrum with the pelvis. An SI joint block injection may be repeated up to three times per year for relief of pain.

In an SI joint block injection approach, a physician uses fluoroscopic guidance (live x-ray) and inserts a needle into the sacroiliac joint to inject lidocaine and steroid. It takes a highly skilled and experienced physician to be able to insert a needle into the sacroiliac joint. For the treatment to be successful, the injection should be followed by physical therapy and/or chiropractic manipulations to provide mobilization and range of motion exercises.