The sacroiliac (SI) joint connects the sacrum, the triangular bone at the base of the spine, to the ilium, the large wing-like bone of the pelvis. SI joint dysfunction is a common cause of lower back pain, accounting for an estimated 15% to 30% of all cases. A typical SI joint injection delivers a mixture of a local anesthetic for immediate relief and a corticosteroid, a powerful anti-inflammatory medication, directly into the joint space under image guidance. This procedure is used for both diagnosis and therapeutic relief. If the injection provides only temporary relief or no relief, a comprehensive reassessment of the treatment plan is necessary.
Reconfirming the Pain Source
A lack of lasting relief from a therapeutic SI joint injection often redirects the focus to the initial diagnosis. Physicians must consider that the pain may not originate from the SI joint, as other spinal or hip conditions can mimic SI joint dysfunction symptoms. The re-evaluation process begins with a detailed review of initial imaging, such as X-rays, MRI, or CT scans, to look for alternative diagnoses like lumbar spine radiculopathy or degenerative hip disease.
To confirm the SI joint as the pain generator, a specific, image-guided diagnostic injection is performed. This procedure involves injecting only a local anesthetic into the joint under fluoroscopic guidance. If the patient experiences at least 75% pain relief while the anesthetic is active, the diagnosis of SI joint dysfunction is confirmed.
If a second diagnostic block provides little to no pain relief, the physician must pivot away from the SI joint as the primary culprit. This outcome suggests the pain is caused by an unrelated issue, such as a compressed nerve root or a hip joint problem. This diagnostic clarity prevents unnecessary future treatments targeting the SI joint and guides the physician toward a correct treatment pathway.
Advanced Non-Surgical Treatment Options
When the SI joint is confirmed as the pain source, but therapeutic injections have failed to provide adequate relief, the next step is often a more intensive, non-surgical intervention. Radiofrequency ablation (RFA) is a common next step, which is a minimally invasive procedure targeting the nerves transmitting pain signals from the joint. RFA uses heat generated by radio waves to temporarily deaden the small sensory nerves that innervate the SI joint.
This nerve treatment offers longer periods of pain relief compared to injections, often lasting between six and 18 months, as it takes time for the nerves to regenerate. The procedure is performed on an outpatient basis and provides relief without the risks associated with major surgery. Patients who experience a temporary response to a diagnostic injection are the best candidates for RFA.
Alongside RFA, a targeted physical therapy program is implemented to stabilize the surrounding structures. Techniques focus on strengthening the core muscles and stabilizing the pelvis to reduce stress on the joint. This includes specific exercises and manual manipulation techniques to improve joint mechanics.
Long-term pain management medications are adjusted to manage chronic discomfort while therapy takes effect. NSAIDs, muscle relaxers, and nerve pain medications may be used to reduce inflammation and manage symptoms alongside these advanced procedures. These non-surgical treatments are pursued for a minimum of six months before considering surgical options.
Considering Sacroiliac Joint Fusion
Sacroiliac joint fusion is the final option for patients who have exhausted all conservative and minimally invasive treatments, including injections, physical therapy, and radiofrequency ablation, without achieving lasting pain relief. The goal of SI joint fusion is to permanently stabilize the joint by encouraging the sacrum and ilium to fuse together. This stabilization reduces the movement within the joint that causes chronic pain.
The procedure is commonly performed using a minimally invasive technique, often called percutaneous fixation. This approach involves inserting metal implants, such as titanium rods or triangular cages, across the joint through small incisions. This results in less tissue damage and a faster recovery than traditional open surgery. Patient selection is reserved for individuals with severe, chronic SI joint pain that has been unresponsive to at least six months of non-operative care.
Patients must have demonstrated a positive response to a diagnostic SI joint injection, confirming the joint as the source of pain, before being considered for fusion. Recovery timelines vary, but patients generally leave the hospital the same day or the next. Full activity returns gradually over several months as the bone begins to grow across the joint. This surgical intervention provides a permanent solution for chronic SI joint dysfunction.