Personnel includes a physician or physician-extender (i.e. Physician Assistant, Nurse Practitioner, Resident, Fellow, etc), an assistant, and a fluoroscopic C-arm operator. Staff members should be familiar with the handling of potential complications. If a CT guided injection is being performed, then a CT technician plays a role in image acquisition.

Patient consent of the injection is obtained after risk and benefits are thoroughly explained and discussed with the patient. Time-out is used to verify patient and site of injection prior to the procedure. The patient is to lie prone, and the identification of the SI joint may commence.

Fluoroscopic guidance:

According to the practice guidelines from the International Spine Intervention Society (ISIS), a patient is prepped and placed in a prone position, and a pillow is placed under the abdomen at the level of the iliac crests. To visualize the inferior portion of the SI joint, the C-arm is initially placed in anterior-posterior (AP) view and may be adjusted laterally or medially until the optimal image is obtained. When the bony planes of the inferior portion of the joints are parallel, the image is considered ideal.

The aforementioned identified area is then marked and sterilized and draped. With intermittent fluoroscopy, the spinal needle is advanced to the inferior part of the SI joint. Once the needle reaches the joint, a distinct popping sensation can be felt by the physician. Once optimal needle position is achieved within the inferior portion of the SI joint, 0.3 to 0.5 ml of contrast is injected into the joint. If the contrast material outlines the SI joint, the placement of the needle is confirmed. There is controversy on the maximum volume of injectate to be used; however, as a rule of thumb, the injectate should be used until there is a firm end-point, extra-capsular escape, or a maximum volume of 2.5 ml is reached.

CT guidance:

CT guidance is also performed with patient in prone position. An initial CT scan is performed and the most direct route to the SI joints bilaterally is identified. The overlying skin is marked. The skin is prepped and draped in sterile fashion. Local anesthesia with approximately 5 mL of 1% lidocaine is administered. Using CT guidance, a 22 gauge spinal needle is inserted into the lower posterior aspect of the SI joints. After confirming satisfactory placement of the spinal needles, 0.5 mL of Kenalog 40 (20 mg) mixed with 0.5 mL of 0.25% bupivacaine is injected into each SI joint. The needles were removed and hemostasis is achieved with compression.

According to a systematic review, a minority of patients experienced immediate transient reactions, such as vasovagal reactions. [9]  The most common being increased pain and soreness. [10] Rarer, but more serious, complications include trauma to the nerves, accidental intervertebral foraminal injection, hematoma, sciatic palsy, meningitis, abscess, and systematic infection. There is also a reported case of pyogenic sacroiliitis and a case of herpes simplex.[11] There may also be a risk posed by the administration of steroids and local anesthetics. A technically unsuccessful rate of 10% has been reported by several studies.[12][13][14][15]

Where there is suspicion for SI joint pain, SI joint blocks are used to diagnose and treat SI joint pain. While SI joint injections can be performed without imaging guidance, according to various studies, there is only a 12% to 22% chance of the needle reaching the SI joint without imaging guidance. Other imaging guidance modalities include ultrasound or CT. When compared to ultrasound guidance, fluoroscopy can confirm injectate being placed intraarticularly, and fluoroscopy is better than CT imaging at visualizing the medicine’s spread from the joint to the surrounding structures.

With diagnostic SI joint injections, when there is more than 75% pain relief while performing previously painful movements, the SI block is deemed successful. Certain physicians may decide also to perform a controlled (dual) local anesthetic block to rule out false positives. [16] There is systematic review evidence that offers moderate support for the use of SI joint injection in chronic low back pain and/or lower extremity pain below the L5 vertebra. Therapeutic SI joint injection can provide prolonged pain relief for patients suffering from SI joint dysfunction. According to one study, SI joint injection with triamcinolone was given to patients with SI joint dysfunction with spondyloarthropathy, demonstrated to reduce pain for more than 6 weeks for 66.7% of participants, and the overall mean duration of pain reduction in these responders was 36.8 plus or minus 9.9 weeks. [17] If steroid injection does not alleviate pain adequately, other interventions may be considered, including prolotherapy, radiofrequency ablation, viscosupplementation, or minimally invasive SI joint fusion.

SI joint injection may be performed by an interprofessional team that includes a pain specialist, radiologist, orthopedic surgeon, rheumatologist and sports physician. It is important to be aware of the anatomy of the SI joint and utilize imaging modalities to achieve higher success. Patients should be educated that the SI injection is not curative and repeat injections may be required. All healthcare workers who perform SI injections should know how to manage the complications that may arise during and after the procedure.