The sacroiliac (SI) joint connects the triangular sacrum at the base of the spine to the large iliac bones of the pelvis. This joint is highly stabilized by strong ligaments and transfers the weight and forces of the upper body to the legs, allowing only a small amount of motion. Pain originating from this joint, known as SI joint dysfunction or sacroiliitis, typically manifests as discomfort in the lower back, buttock, or hip region. This pain can also radiate down the leg, sometimes mimicking sciatica.
Confirming the Diagnosis
Identifying the SI joint as the specific source of pain is challenging because its symptoms often overlap with those of other conditions, such as lumbar disc herniation or hip pathology. Diagnosis relies on a combination of physical examination and diagnostic procedures. Clinicians use specific physical maneuvers, known as provocation tests, to stress the joint and attempt to reproduce the patient’s pain.
Examples include the FABER (Flexion, Abduction, and External Rotation) test, the compression test, and the thigh thrust test. The likelihood of SI joint involvement increases significantly if three or more of these tests provoke pain. Imaging studies like X-rays or MRI are primarily used to rule out other causes, such as fractures or inflammatory arthritis.
The most specific method for confirming SI joint pain remains the image-guided diagnostic injection. This procedure involves injecting a local anesthetic directly into the joint under fluoroscopic guidance. A positive diagnosis requires a significant, temporary reduction in the patient’s pain—typically 50% to 75% relief—shortly after the anesthetic is administered.
Treatment Paths for Relief
Once the diagnosis is confirmed, the initial approach focuses on non-surgical, conservative methods aimed at reducing inflammation and restoring joint mechanics. Physical therapy is a primary intervention, concentrating on stabilizing the pelvis and strengthening the muscles that support the lower back and hips. Anti-inflammatory medications are often used in conjunction with therapy to manage pain and reduce inflammation.
If conservative care fails to provide sustained relief, the next step involves interventional procedures. Therapeutic injections, which combine a corticosteroid with a local anesthetic, can be administered directly into the SI joint to decrease inflammation and offer longer-lasting pain reduction. The effect of these injections is variable and may last from several weeks to a few months.
For patients experiencing chronic pain that returns after injections, radiofrequency ablation (RFA) may be considered. RFA is a minimally invasive technique that uses radio waves to generate heat, damaging the small nerves that transmit pain signals from the SI joint to the brain. This procedure aims to provide pain relief for a longer duration, often maintained for six to twelve months or longer.
Addressing the Question of a Cure
Achieving a complete “cure” for SI joint pain depends on the underlying cause and how the term is defined in musculoskeletal disorders. For many, success means achieving long-term functional restoration and substantial pain reduction, effectively putting the condition into remission. SI joint dysfunction often involves chronic instability or misalignment, which requires ongoing maintenance through exercises and lifestyle adjustments even after initial relief.
For pain linked to hypermobility or instability that does not respond to non-surgical management, the most definitive intervention is sacroiliac joint fusion. This surgical procedure stabilizes the joint permanently by fusing the sacrum and ilium bones together, typically using small metal implants. Fusion is reserved as a last resort when all other treatment paths have failed to provide adequate functional improvement.
Minimally invasive SI joint fusion has demonstrated high success rates, with 82% to 92% of patients reporting significant pain improvement and functional benefit at one or two years post-surgery. Fusion represents the closest option to a permanent anatomical solution, offering lasting stability where instability is the source of chronic pain.