The sacroiliac (SI) joints connect the triangular bone at the base of the spine (the sacrum) to the pelvic bones (the ilium). Reinforced by dense ligaments, these joints absorb shock and transfer the weight of the upper body to the hips and legs during movement. Pain originating from this area, often called sacroiliitis or SI joint dysfunction, is a significant cause of discomfort in the lower back and buttocks.
Understanding Sacroiliac Joint Pain
The SI joint is designed for stability, but problems arise when its normal motion is altered. Dysfunction results from either hypermobility (too much movement leading to instability) or hypomobility (too little movement causing stiffness). Both conditions lead to pain and inflammation.
Symptoms include a persistent ache in the lower back and buttock, often on one side, which can spread down the back of the leg, mimicking sciatica. The pain is aggravated by activities that stress the pelvis, such as standing on one leg, climbing stairs, or prolonged sitting or standing. Common causes include traumatic injury, degenerative arthritis, prior lumbar spine surgery, or hormonal and biomechanical changes during pregnancy.
Factors Determining Long-Term Prognosis
Most cases of SI joint pain are not permanent and resolve with appropriate treatment. However, SI joint pain can become chronic, defined as lasting longer than three to six months. The prognosis is heavily influenced by the underlying cause and the timeliness of the diagnosis.
The etiology of the pain is a major factor; cases resulting from inflammatory arthritis, such as ankylosing spondylitis, require ongoing disease management. Pain that begins during pregnancy typically resolves on its own within several months postpartum. Atraumatic cases (those without a direct injury) are more likely to resolve completely compared to those resulting from significant trauma.
Timely and accurate diagnosis is essential because SI joint pain is often mistaken for conditions like a herniated disc or facet joint syndrome. When the pain is not correctly identified, the lack of targeted treatment allows the condition to persist and become chronic. For patients with chronic SI joint dysfunction, the average duration of symptoms before effective treatment is often reported around 43 months, highlighting the risk of prolonged disability when management is delayed.
Non-Surgical Strategies for Resolution
Initial treatment focuses on conservative, non-invasive methods to reduce inflammation and restore joint stability. This approach typically begins with a trial of over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen. Muscle relaxers may also be prescribed to address muscle spasms that accompany the joint pain.
Physical therapy is a cornerstone of conservative management, focusing on lumbopelvic stabilization exercises. These exercises strengthen the muscles surrounding the pelvis and lower back, including the gluteal muscles, lower abdominals, and hamstrings. Improving the coordination of these muscle groups is necessary for long-term recovery and reducing strain on the joint.
External support can be provided using an SI joint belt, a non-elastic strap worn temporarily around the pelvis. The belt provides compression and stability, which temporarily reduces abnormal joint motion and alleviates symptoms. Lifestyle modifications are also incorporated, such as practicing better ergonomics and avoiding activities that exacerbate the pain, allowing the joint to rest.
When Advanced Intervention is Necessary
If conservative measures fail to provide satisfactory relief after three to six months, advanced interventions are considered. The first step is often a diagnostic and therapeutic corticosteroid injection into the joint, performed under imaging guidance. This injection combines a local anesthetic and a powerful anti-inflammatory steroid, confirming the SI joint as the source of pain and offering temporary relief.
If pain returns after the injection effects wear off, radiofrequency ablation (RFA) may be used for longer pain control. This minimally invasive procedure uses heat energy to temporarily neutralize the sensory nerves that transmit pain signals from the SI joint. While not a cure, RFA can offer pain relief for several months.
For a small number of individuals with severe chronic pain resistant to all other treatments, minimally invasive SI joint fusion surgery may be necessary. This procedure permanently stabilizes the joint by fusing the sacrum and ilium together. Fusion is reserved as a final option for patients who meet strict criteria, including unsuccessful nonoperative management and significant pain reduction following a diagnostic injection.