What is a sacroiliac joint injection?
The sacroiliac (SI) joints sit low in the back, where the base of the spine - the sacrum - meets the pelvis on each side. They carry load and absorb shock, and when one becomes inflamed or moves abnormally it can cause pain across the lower back, buttock, and hip, sometimes spreading into the groin or upper thigh. Because this can mimic pain from a disc or nerve, the SI joint is easy to overlook.
An SI joint injection places local anesthetic, often with a corticosteroid, directly into or around the joint. It serves two purposes: if numbing the joint clearly relieves your usual pain, it confirms the SI joint as the source; the steroid then works to reduce inflammation and give more lasting relief.
What happens during the procedure
This is an image-guided procedure. Using fluoroscopy - live X-ray - your specialist numbs the skin and guides a fine needle into the joint, usually confirming the position with a small amount of contrast dye before injecting. Light sedation may be offered. You are observed afterwards according to the medication and sedation used.
Benefits and considerations
The temporary response to local anesthetic can add diagnostic information, and corticosteroid may reduce inflammation. The timing and degree of response vary, and some people have little or no benefit. The result is interpreted with your history and examination and may inform a wider plan that includes activity guidance or physiotherapy.
What to expect afterwards
Arrange an escort if sedation is used and follow the clinic’s instructions for driving and activity. Temporary soreness or a pain flare can occur. Record how your usual pain changes after the injection and seek urgent advice for new weakness, fever or severe headache.
How we approach your care
- 01
Find the true source
We begin with a thorough history and examination, supported by imaging where appropriate, to pinpoint the precise source of the problem.
- 02
Consider appropriate options
Where clinically appropriate, we consider established non-surgical options before surgery. The plan depends on the diagnosis, symptoms, health and priorities of the individual patient.
- 03
A plan built around you
Every step is explained clearly, so you always understand your options and what comes next.
This may help if
- You have pain low down on one side of the back, over the buttock or hip
- The pain worsens with standing, climbing stairs, or rolling over in bed
- Examination points to the sacroiliac joint rather than a disc or nerve
- You would like to confirm the joint is the source and gain some relief
Suitability can only be assessed after reviewing your symptoms, examination, relevant imaging and previous treatment.
Common questions
Where is the sacroiliac joint and why does it hurt?
The sacroiliac joints sit low in the back, where the base of the spine meets the pelvis on each side. They carry load and absorb shock. When one becomes inflamed or moves abnormally, it can cause pain across the lower back, buttock, and hip, sometimes spreading into the groin or thigh.
Is the injection for diagnosis or treatment?
It may provide diagnostic information and treatment. A temporary change after local anesthetic can support the SI joint as a pain source, but the result is interpreted with your examination and imaging. Corticosteroid may be included to reduce inflammation.
How long does the relief last?
The timing, degree and duration of response vary, and some people have little or no benefit. Your specialist will review the response before considering a repeat injection or another treatment.
Does the injection hurt?
The skin is numbed with local anesthetic first, so most people feel pressure rather than sharp pain, and light sedation can be offered. There is no incision - only a fine needle guided into the joint under X-ray. The injection itself usually takes just a few minutes.
Will it cure the problem?
No. It may reduce inflammation but does not correct every cause of SI-region pain. It may be used alongside activity guidance or physiotherapy when appropriate.
What if the injection does not help?
That is useful information too. If numbing the joint brings little or no change in your usual pain, the sacroiliac joint is less likely to be the main source, and we look elsewhere. Either way, your response helps direct the next, least-invasive step in your care.