What is the Sacroiliac Joint and what does it do?
The Sacroiliac joint (SI joint) is a space between the sacrum and ilium (hip bones) in the pelvis. The primary function of the SI joints is to absorb shock between the upper body and the pelvis and legs. The SI joint typically has little motion. Small movements at the joint help with shock absorption and forward/backward bending. The joint is reinforced by strong ligaments surrounding it.
Related Article: Sacroiliac Joint Injections
Sacroiliac joint pain or dysfunction can cause low back and/or leg pain that can mimic sciatic symptoms. Too much movement (hypermobility or instability) can cause the pelvis to feel unstable and lead to pain. Pain from too much motion is typically felt in the lower back and/or hip and may radiate to the groin. Too little movement (hypomobility or fixation) may cause muscle tension and pain typically felt on one side of the low back or buttocks and can radiate down the back of the leg. Inflammation of the joint can also cause pelvic pain and stiffness and be caused by infection, rheumatologic (arthritic) conditions or other causes. SI joint dysfunction is more common in young and middle-aged women especially those that are pregnant or recently given birth. Those that have had a spinal fusion of their lumbar spine are also at increased risk for possible SI joint pain/dysfunction.
Diagnosing SI Joint pain
SI joint pain was once thought to be a more common problem. However, only about 13% of chronic low back pain patients have pain confirmed to be caused by the SI joint. Due to lack of a single diagnostic test, and pain that mimics other conditions such as a herniated disc or facet joint arthritis, SI joint pain is difficult to diagnose. The diagnosis is more likely in patients with a history of lumbosacral fusion, concomitant inflammatory arthritides such as psoriatic arthritis, and of advanced age. Imaging tests of the area are typically less helpful in diagnosing a painful SI joint. There are several physical examination tests that help a provider consider a diagnosis of SI joint pain, but unfortunately the test results can often differ between healthcare providers. The gold standard for making the diagnosis is precise, image-guided SI joint injection with local anesthetic (numbing medication).
Treating SI Joint pain
Options for treatment range from conservative to surgical, but most patients can be managed with nonsurgical treatment. In early stages, brief periods of rest, application of ice or heat, and oral medications such as acetaminophen or NSAIDs (nonsteroidal anti-inflammatory medication) can help reduce pain, inflammation or spasms. Manual manipulation (by a chiropractor, osteopathic physician, or physical therapist) can help if pain is caused by hypomobility of the SI joint. Bracing may help stabilize a hypermobile joint. SI joint injections can be performed not just for diagnostic, but also therapeutic purposes with the use of corticosteroids to reduce pain and inflammation.
Refractory cases that don’t respond to the usual conservative measures may be a candidate for other treatment options. Regenerative therapies, including PRP or stem cell injections may be helpful for chronic SI joint pain. Radiofrequency neurotomy (RF ablation) of the sacral lateral branches can be successful in select situations. Minimally invasive surgical fusion of the SI joint is also available.