Analgesic Effect of Sacral Submultifidus Block as an Adjunct to Sacroiliac Joint Injection

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

The aim of this study is to assess whether the addition of sacral submultifidus block to standard image-guided SIJ injection provides superior analgesia and functional improvement compared with SIJ injection alone in patients with chronic SIJ-mediated pain.

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 (1). 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 (2). 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 (3).

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 (4). 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 (5). 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 (6).

Given the limitations of conventional SIJ injections, interest has grown in adjunctive regional blockade techniques that more comprehensively target periarticular neural pathways (7). 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 (4). 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 (8).

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.

Inclusion Criteria:

-patients aged above 21 years, both genders diagnosed with chronic sacroiliac joint pain with a rating on the numeric pain rating scale (NPRS) of at least 5, without radiculopathy lasting 3 months or longer, and Positive SI provocative tests: usually > 3 positive tests 1.Compression : While lying on your side, downward pressure is applied to the top of your pelvis. 2.Distraction : While lying on your back, outward pressure is applied to the front of your pelvic bones. 3.Thigh thrust: Lying near the edge of the table, one leg is pulled to your chest while the other is allowed to hang off, creating pelvic torsion. 4.Gaenslen: (Lying near the edge of the table, one leg is pulled to your chest while the other is allowed to hang off, creating pelvic torsion). 5.FABER: (Flexion, Abduction, External Rotation) *Failure of conservative therapy * Radiological exclusion of lumbar pathology. * Diagnostic SIJ block producing ≥75% pain relief.

Exclusion Criteria:

• 1. refusal to participate. 2. Allergy or contraindication to local anesthetics. 3. Coagulation disorders or ongoing anticoagulant therapy. 4. Infection at the block injection site. 5. Chronic opioid use or substance abuse. 6. Neurological or psychiatric disorders affecting pain assessment. 7. Pregnancy.