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Sacroiliac joint injections and lateral branch procedures

The sacroiliac joint links the base of the spine to the pelvis and is a recognised source of low back and buttock pain. Injection into the joint can be both diagnostic and therapeutic; where it confirms the joint as the source, radiofrequency treatment of the supplying nerves may follow.

Sacroiliac joint pain is under-recognised. It is usually felt lower than typical lumbar pain — over the buttock, sometimes referring into the groin or down the back of the thigh — and it commonly follows pregnancy, a fall onto the buttock, a motor vehicle injury, or fusion surgery higher in the spine.

Why examination alone is not enough. No single physical test reliably identifies the sacroiliac joint as the pain source, and imaging often looks unremarkable even when the joint is symptomatic. Clusters of provocation tests improve accuracy but do not settle the question. Image-guided injection remains the most reliable way to establish whether the joint is involved.

The injection. Under X-ray guidance a needle is placed into the joint and local anaesthetic, usually with anti-inflammatory medication, is injected. Substantial relief in the hours afterwards supports the diagnosis. Any longer benefit from the anti-inflammatory component develops over the following days and varies considerably between people.

Lateral branch radiofrequency. The sacroiliac joint receives nerve supply from lateral branches arising from the sacral nerves. Where injection confirms the joint as a pain source but relief is short-lived, radiofrequency treatment of these nerves may be considered. Because the nerve supply is more variable than that of the facet joints, results are less predictable than for spinal facet neurotomy, and Dr Martin will be clear about that when discussing it.

On the day. You lie face down. The procedure takes around 20–30 minutes. Light sedation is available. You go home the same day and should arrange a driver if sedated.

Risks. Whilst pain procedures are generally safe and well tolerated, all procedures carry risks. The specific risks relevant to you and your procedure will be discussed with you, and written information provided, before you decide to proceed.

What else matters. Sacroiliac pain frequently responds to targeted rehabilitation addressing pelvic and hip control. Injection is most useful when it enables that work rather than substituting for it.