What is a Sacroiliac Joint Injection?

 

A Sacroiliac (SI) Joint Injection is a procedure used to diagnose and treat pain arising from
the sacroiliac joints and the posterior pelvic ligaments, which are located at the junction of
the spine and the pelvis. These joints help absorb shock and transfer weight between the
upper body and legs. If they become inflamed or dysfunctional, they can cause lower back,
buttock, or leg pain. The injection involves administering local anaesthetic and steroid
directly into the joint under imaging guidance.

What conditions do we offer this for?

We may offer this procedure to patients with:

  • Sacroiliac joint pain or dysfunction
  • Low back pain, unresponsive to Facet joint treatments
  • Post-traumatic or post-surgical pain in the lower back or pelvic region
  • Pain that worsens with standing, walking, or prolonged sitting
  • To confirm the SI joint as the pain source before further treatment (e.g. radiofrequency denervation)

Why is it done?

A sacroiliac joint injection is performed to:

  • Help confirm whether the SI joint is the true source of pain (diagnostic)
  • Provide targeted relief from lower back and buttock pain
  • Reduce inflammation and improve mobility
  • Facilitate physiotherapy and rehabilitation
  • Guide further treatment options if pain relief is short-lived

What does the procedure involve?

  • You will lie on your stomach for the injection.
  • The skin is cleaned and numbed with local anaesthetic.
  • Under X-ray or ultrasound guidance, a fine needle is placed into the sacroiliac joint.
  • A combination of local anaesthetic and steroid is injected into the joint space.
  • The procedure takes approximately 15–30 minutes and is performed as a day case.

Benefits

  • Targeted pain relief that may last weeks to months
  • Diagnostic clarity to guide future treatment (e.g. radiofrequency ablation)
  • Reduced need for oral pain medications
  • Improved mobility, sitting, and walking tolerance
  • Supports physiotherapy and functional recovery

Side Effects

Very Common side effects

(may affect more than 1in 10 patients):
  • Pain or bruising at the injection site
  • Temporary increase in pain after the injection
  • Mild numbness or tingling in the buttocks or leg

Common side effects

(may affect up to 1 in 10 patients):
  • Facial flushing, nausea, or dizziness
  • Increased blood sugar (especially in diabetics)

Uncommon side effects

(may affect up to 1in 100 patients):
  • Infection at the injection site
  • Leg weakness or heaviness (temporary)

 Rare side effects

(may affect up to 1 in 1,000 patients):
  • Nerve injury or persistent numbness
  • Bleeding or haematoma
  • Allergic reaction to a steroid or anaesthetic

Aftercare Advice

  • You will be observed briefly and can usually go home the same day.
  • Avoid driving for 24 hours.
  • Pain may worsen temporarily before improving — use ice packs and simple painkillers if needed.
  • Resume activities gradually; avoid high-impact activity for a few days.
  • A follow-up appointment will help assess the effectiveness of the injection and plan further treatment if required.

When to Seek Medical Attention

Please attend A&E immediately if you experience:
• Fever, chills, or signs of infection at the injection site
• New or worsening leg numbness or weakness
• Loss of bladder or bowel control
• Severe or ongoing back pain not relieved by usual medication