Overview
Sacroiliac joint block is a targeted treatment used when the sacroiliac joint is suspected to be the source of persistent low back or pelvic pain. The sacroiliac joints sit at the base of the spine and transfer load between the upper body and the legs. Irritation or inflammation in these joints may cause pain felt in the lower back, buttocks, groin, hips, or upper thighs.
Symptoms often worsen with standing, walking, climbing stairs, or prolonged sitting. Sacroiliac joint pain can be difficult to diagnose because it may mimic disc related or facet joint pain.
A diagnostic sacroiliac joint block can help confirm whether the joint is contributing to symptoms. If the block provides clear but temporary relief, radiofrequency ablation may be considered to provide longer lasting pain control.
Who this treatment helps
Sacroiliac joint block or ablation may be considered for people with:
- Persistent low back or buttock pain suspected to arise from the sacroiliac joint
- Pain that worsens with standing, walking, or climbing stairs
- Pelvic or lower back pain following pregnancy
- Pain related to degenerative joint changes
- Discomfort following trauma or altered pelvic mechanics
- Limited improvement with physiotherapy, medication, or manual therapy
- Clinical examination suggesting sacroiliac joint involvement
A consultation is required to confirm suitability and identify whether the sacroiliac joint is the likely source of pain.
What is a sacroiliac joint block or ablation
A sacroiliac joint block involves injecting local anaesthetic, sometimes combined with steroid medication, into or around the sacroiliac joint. This helps reduce inflammation and pain while also serving as a diagnostic test.
If pain improves significantly after the injection it suggests the sacroiliac joint is an important contributor to symptoms.
If the relief is temporary, radiofrequency ablation may be recommended. Radiofrequency ablation uses controlled heat to interrupt the small sensory nerves that supply the sacroiliac joint. These nerves carry pain signals but do not control movement or strength, so joint stability is preserved.
Both procedures are performed using imaging guidance to ensure accurate needle placement and improve safety.
What to expect during the procedure
- Your consultant reviews symptoms, examination findings, and imaging
- You lie comfortably on the procedure table
- The skin over the lower back is cleaned and numbed
- Imaging guidance is used to position the needle accurately
- A diagnostic injection is performed
- If proceeding to ablation, specialised probes are positioned near the sensory nerves
- You are monitored briefly before returning home
The procedure is usually completed as a day case.
After the procedure
After a diagnostic sacroiliac joint block you may notice:
- Immediate pain relief due to the local anaesthetic
- Temporary numbness or lightness around the joint
- Mild soreness at the injection site
After radiofrequency ablation it is common to experience:
- Local tenderness for several days
- Gradual improvement over two to six weeks
- Occasional short term flare ups
Your consultant may recommend:
- Avoiding strenuous activity for a short period
- Continuing physiotherapy to improve pelvic stability
- Gradual return to normal activities
- Monitoring symptoms and keeping a symptom diary
Benefits
- Helps confirm whether the sacroiliac joint is the source of pain
- May reduce joint inflammation and pain
- Minimally invasive treatment approach
- Radiofrequency ablation may provide longer lasting relief
- Supports improved mobility and rehabilitation
- May reduce reliance on pain medication
Possible risks and side effects
Sacroiliac joint block and ablation are generally safe when performed by experienced clinicians, although some risks may occur.
- Temporary increase in pain
- Local bruising or soreness
- Temporary numbness
- Infection, which is rare
- Bleeding
- Allergic reaction to medication
- Very rare nerve irritation
Your consultant will discuss all potential risks and suitability during assessment.
When to consider other options
If symptoms do not improve your consultant may discuss other treatments such as facet joint treatments, physiotherapy or pelvic stabilisation programmes, medication optimisation, or other minimally invasive procedures depending on the cause of symptoms.
Safety note
Please inform your consultant if you take blood thinning medication, have diabetes, allergies, are pregnant, or have an active infection. Depending on the medications used you may need someone to accompany you home after the procedure.
Arrange a consultation to discuss whether sacroiliac joint block or ablation may be appropriate for managing your low back or pelvic pain.
You can also explore our low back pain treatments, view all pain treatments, or learn more about our pain management services.