Sacroiliac (SI) joint injections may be used to diagnose and treat pain stemming from the SI joint and/or the posterior pelvis. The SI joint is a complex anatomic region and the accuracy of the injection often determines the success of obtaining pain relief.
How Sacroiliac Joint Injections Work
SI joint pain may originate from within the joint itself or from surrounding structures, such as the SI ligament. An SI joint injection may be given around the joint—periarticular injection or within the joint—intra-articular injection. Typically, corticosteroids mixed with anesthetics are used.
Intra-articular injections and peri-articular injections
The two types of SI joint injections are:
- Intra-articular injections. These injections are given within the synovial capsule of the joint.
- Periarticular injections. These injections usually target the nerves in the posterior pelvis since the majority of the neural innervation of the SI joint is concentrated in the region behind the joint. These injections are given in the fibrous, ligamentous area of the joint.
In the peri-articular technique, the exact location for the injection is unclear, with doctors suggesting injecting at varying depths to reach the desired amount of pain-relief.1 Typically, fluoroscopy is used to guide the needle to the accurate location in an intra-articular technique. For periarticular injections, ultrasound guidance may be used. A contrast dye can be used to help guide the needle to the proper location and avoid injecting into a blood vessel.
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Success Rates of Sacroiliac Joint Injections
The success rates of different types of SI joint injection have reported conflicting results. Sometimes, both intra-articular and periarticular injections may be given together to increase injection efficacy. Some studies suggest that the peri-articular injections may be more effective in providing pain relief compared to intra-articular injections.1
Not all SI treatment injections are effective in the long-term. However, these injections may be used to diagnose SI joint pain. The injections may also help to improve the functional outcome of the SI joint through participation in rehabilitative treatments such as physical therapy and other therapies.
When Sacroiliac Joint Injections Are Given
SI joint injections may be given when there is a positive pain response to an SI joint provocative test (moving the SI joint in various directions to check the source of pain) and when SI joint pain is suspected clinically.
SI joint injections are usually not given if a patient is pregnant or has an infection, blood disorder, certain types of diabetes mellitus, or cancer.
Risks of Sacroiliac Joint Injections
Risks related to SI joint injections usually occur infrequently. Typical risks include:
- An allergic reaction to the medications used in the injection.
- Bruising and/or soreness at the injection site.
- Infection at the injection site, deeper tissues within the joint, or the pelvis.
- Nerve or spinal cord damage if the needle penetrates a nearby lumbar nerve or the epidural space.
Post-injection pain and soreness are not considered a risk and usually resolves within a few days of the injection.