Analgesic Effect of Sacral Submultifidus Block as an Adjunct to Sacroiliac Joint Injection: A Randomized Controlled Double-Blind Trial

Sacroiliac joint (SIJ) pain is an under-recognized significant contributor to chronic low back pain, with estimates indicating that it accounts for approximately 10-30% of mechanical low back pain presentations . The SIJ is a complex diarthrodial-amphiarthrodial articulation between the sacrum and ilium that functions within the weight-bearing system of the pelvis and lumbosacral spine, stabilized by a dense ligamentous network and influenced by surrounding musculature . Pain originating from the SIJ often manifests as deep aching discomfort that can radiate to the buttocks, groin, or lower extremity and may be difficult to differentiate from lumbar or hip pathology based on clinical features alone .

The intricate innervation of the SIJ contributes to diagnostic challenges. Abundant anatomical evidence suggests that pain signals from both intra-articular and extra-articular structures, including the posterior sacroiliac ligaments and dorsal sacral rami, converge to produce symptomatology, underscoring the potential utility of targeted neural blockade . Image-guided intra-articular injections with local anesthetic and corticosteroids are commonly used for both diagnostic confirmation and therapeutic pain relief, yet responses to these interventions are variable and often short-lived . Systematic reviews have demonstrated modest analgesic effects of SIJ injections overall and highlight significant heterogeneity in procedural techniques and outcomes, emphasizing the ongoing need for optimized interventional strategies .

Given the limitations of conventional SIJ injections, interest has grown in adjunctive regional blockade techniques that more comprehensively target periarticular neural pathways . Fascial plane and lateral branch blocks aimed at disrupting nociceptive input from the posterior sacral nerve supply have shown physiological efficacy in cadaver and clinical studies, though high-quality randomized data remain limited . The sacral submultifidus block is a novel regional anesthetic technique that targets the dorsal rami beneath the multifidus muscle, potentially augmenting pain control when combined with SIJ injection by addressing extra-articular and posterior nociceptive sources .

So addition of ultrasound-guided sacral submultifidus block to SIJ injection produces superior pain relief and functional improvement compared with SIJ injection alone .

Some patients may only require one injection, while others may require several injections. As a general guideline, injections may be administered once every 2 weeks, and no more than 3 injections may be given per year In general, if the first injection provides significant relief, additional injections may be recommended. However, the exact timing can vary based on the doctor's guidance, the patient's response to the treatment, and the type of injection The long-term outcomes of SI joint injections can vary depending on a number of factors, including the underlying cause of the pain, the patient's overall health, the patient's response to the injection, and the type of injection used.