Sacroiliac arthritis refers to degeneration of the cartilage at the joint on either side of your lower back where the sacrum meets the ilium (right by the “dimples” in your lower back). The lower portion of this joint is a synovial joint (with articular hyaline cartilage). Sacroiliac arthritis and dysfunction is often implicated in cases of chronic lower back pain. “Sacroilitis” is often used interchangeably with sacroiliac arthritis however sacroilitis can sometimes denote more acute active inflammation from an inflammatory arthritis such as ankylosing spondylitis rather than chronic cartilage degeneration from osteoarthritis.
Causes of SI joint arthritis include wear and tear on the SI joint overtime. There are many factors that can precipitate wear and tear. Some factors can be biomechanical with a possible predisposition from leg length discrepancy, tight/poorly balanced muscles, hormonal changes with ligamentous laxity (in pregnancy, for instance), etc. There are inflammatory arthropathies which characteristically affect the SI joints as well including the seronegative spondyloarthropathies (such as ankylosing spondylosis).
Symptoms of SI joint syndrome are often hard to distinguish from other types of low back pain. In most cases, there is a confusing pattern of back and pelvic pain that mimic each other, making diagnosis of SI joint syndrome very difficult. The most common symptoms of SI joint syndrome include:
Low back pain
Difficulty sitting in one place for too long due to pain
Procedural treatment for SI joint disease can include cortisone injections into the sacroiliac joints. There is also a procedure that can ablate or burn the nerves responsible for communicating pain signals from the SI joint to the brain. Regenerative injections including platelet-rich plasma (PRP) injections are also being used experimentally to provide a healthier environment to promote healing.