The SI joint is a common and frequently overlooked source of lower back, buttock, and hip pain. A sacroiliac joint injection both confirms the diagnosis and provides therapeutic relief — forming the foundation for longer-term treatment decisions.
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Who This May Help
SI joint injections may be an option if you have pain in the lower back, buttock, or hip that is suspected to originate from the sacroiliac joint. SI joint pain is often one-sided and can mimic disc or facet joint pain — making a diagnostic injection an important step in identifying the true source. It may be particularly relevant for patients whose lower back or hip pain worsens with activities such as climbing stairs, transitioning from sitting to standing, or rolling over in bed, and who have not found lasting relief through physical therapy or medications.
A consultation with our clinical team will determine whether you are a candidate.
Procedure Overview
How the Sacroiliac Joint Injection Works
The sacroiliac joint connects the sacrum — the large triangular bone at the base of the spine — to the pelvis on each side. When this joint becomes inflamed, arthritic, or dysfunctional, it can generate significant pain in the lower back, buttock, and hip that is often mistaken for disc or nerve pain. A sacroiliac joint injection places anti-inflammatory medication directly into the joint under image guidance, both reducing inflammation and confirming whether the joint is the primary pain source.
The procedure is performed using fluoroscopy to ensure accurate needle placement into the joint. It is a same-day outpatient procedure — patients go home the same day. Carefully monitoring your pain response in the hours after the injection is an important part of the diagnostic process and guides all subsequent treatment decisions.
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Recovery & Results
What to Expect After the Procedure
SI joint injections are same-day outpatient procedures. Most patients resume normal light activities the same day with minimal soreness at the injection site. The most important task after the procedure is to monitor your pain level carefully and note how much relief you experience and for how long — this diagnostic information drives all subsequent treatment decisions.
Therapeutic relief from the injection typically lasts several weeks to months. If the injection confirms the SI joint as the primary pain source, lateral branch radiofrequency ablation is often the next step — providing more durable relief lasting months to years. For patients with significant joint instability who do not respond adequately to these approaches, referral to a spine surgeon for evaluation of posterior SI joint fusion may be appropriate.
Frequently Asked Questions
Common Questions
A sacroiliac joint injection places medication directly into the SI joint — the joint connecting the sacrum to the pelvis on each side. The injection serves two purposes: it confirms whether the SI joint is the source of your pain, and it can provide therapeutic relief by reducing inflammation inside the joint.
Sacroiliac joint pain typically produces aching or sharp pain in the lower back, buttock, or hip that may radiate into the back of the thigh. It is often one-sided and can be difficult to distinguish from disc-related or facet joint pain without a diagnostic injection. Activities such as climbing stairs, standing on one leg, transitioning from sitting to standing, or rolling over in bed often aggravate SI joint pain.
After the injection, you will be asked to monitor your pain level and note how much relief you experience and for how long. If the injection produces significant improvement, it confirms that the sacroiliac joint is contributing to your pain and helps guide the next step in your treatment plan. This diagnostic information is essential before recommending any longer-term treatment.
If the SI joint injection confirms the SI joint as the primary pain source, longer-term options include lateral branch radiofrequency ablation — which interrupts the nerves supplying the SI joint to provide more durable relief lasting months to years. For patients with significant SI joint instability or degeneration who do not respond adequately to injections and ablation, referral to a spine surgeon for evaluation of posterior SI joint fusion may be appropriate.
Lateral branch radiofrequency ablation targets the lateral branch nerves that supply the sacroiliac joint with heat energy, interrupting their ability to transmit pain signals. It is typically performed after SI joint injections have confirmed the joint as the pain source, and can provide relief lasting six months to two years or more. Like all radiofrequency ablation, it can be repeated when pain returns.
Posterior SI joint fusion is a surgical option considered for patients with confirmed SI joint pain who have not achieved adequate long-term relief from injections and radiofrequency ablation — particularly those with significant joint instability or degeneration. When fusion is clinically appropriate, we refer patients to spine surgeons who specialize in this procedure. Our role is to ensure that all appropriate interventional options have been evaluated before a surgical referral is made.
Schedule a Consultation
A consultation is the right starting point. Our clinical team will evaluate your pain pattern and determine whether a sacroiliac joint injection is an appropriate next step.
