Sacral lateral branch block and sacro-iliac joint injection overview

Identifying pain from the joints

A lateral sacral branch block involves injecting local anaesthetic onto the nerves of the sacro-iliac joints at the base of the spine. It is used as a diagnostic tool to determine whether back pain is arising from these joints.

The procedure temporarily interrupts pain signals from the sacro-iliac joints. If it results in a significant reduction in back pain, this indicates that these joints are likely to be the source of the pain. In the case of a sacro-iliac joint steroid injection, pain relief may last for several weeks.

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Sacral lateral branch block and sacro-iliac joint injection preparation

Preparing for your diagnostic procedure

A lateral sacral branch block or sacro-iliac joint injection may be recommended for lower back pain arising from the sacro-iliac joints.

As this is primarily a diagnostic procedure, it is important that your usual pain can be reproduced at the time of the procedure. You should stop taking pain medication around 5-6 hours beforehand.

If you do not have pain on the day of the procedure, we may suggest postponing it to a later date.

You should avoid undergoing any other medical procedures, such as dental treatment or a colonoscopy, within 48 hours before or after a lateral sacral branch block or sacro-iliac joint injection.

Please let us know ahead of the procedure if:

  • You are taking any antibiotics.
  • You have a pacemaker or defibrillator.
  • You are ill, in which case we may need to postpone the procedure.

You should also not drive yourself to or from the appointment, or drive during the 24-hour period after the procedure.

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Sacral lateral branch block and sacro-iliac joint injection procedure

What to expect during your procedure

The procedure is performed under light sedation using X-ray guidance, followed by observation and assessment of any changes in your usual pain.

1. Preparation and sedation

You will lie face down on a theatre table while an IV line is placed to administer light sedation.

2. Injection site preparation

The injection area is cleaned and numbed with local anaesthetic before a thin needle is inserted.

3. X-ray guided placement

The needle is guided into the correct position using a mobile X-ray unit.

4. Recovery and pain assessment

You will remain under observation for around one hour and report whether your usual pain has reduced and by how much.

5. Pain diary

You will usually be asked to keep a pain diary for around one week to track changes in the level and intensity of your pain.

After your sacral lateral branch block or sacro-iliac joint injection

Recovery and monitoring after the procedure

After the procedure you are able to return home (although as explained in the preoperative instructions above, you should not drive yourself. There is no restriction on day-to-day activities. In some (relatively rare) cases there may be some discomfort and/or bruising to the skin at the injection site. Any feeling of numbness in the legs or buttocks generally goes away within a few hours.

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Sacral lateral branch block and sacro-iliac joint injection risks

Possible complications to be aware of

A lateral sacral branch block procedure or sacro-iliac joint injection is a relatively low risk procedure – however all medical treatment comes with some level of risk. Possible complications may include:

Bleeding

Minor bleeding may occur at the injection site.

Infection

A small risk of infection is present.

Pain at injection site

Temporary soreness may occur where the needle was inserted.

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  • Comprehensive pain assessments
  • Individual treatment planning
  • Medication review and optimisation

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