Facet joint medial branch blocks for diagnosing pain

The spine is a column of bones arranged one on top of the other. The bones are linked at the back by joints called facet joints, on each side. The facet stabilises the spine, while allowing movement.

The facet joints can become painful due to ‘wear and tear’ (degenerative change) or injury. Pain is felt around the facet joints and can spread.

Pain from the joints of the lower back is often felt in the buttocks and upper legs. Pain from the joints in the neck can spread into the back of the head, the upper back, and shoulders.

When the facet joints are tender and sensitive, the muscles that are close can become tight and painful.

Facet joint medial branch block

This is a procedure where nerve fibres connected to certain facet joints are blocked by local anaesthetic injections. These are done so the doctors can assess if these are the source of your pain.

Other treatment options

The decision about treatment is shared between you and your doctor. If there are any other treatment options available, your doctor will discuss these with you. Your doctor can give you up-to-date information about the chances of this being a successful treatment for you, and how it fits into the best pathway of care.

If you are undecided about treatment, more advice and information can be provided. Please speak to your doctor about this.

Side effects

As with any procedure, you can get side effects. However, these are usually minor, but there are risks with this procedure.

Not everyone will get them, but possible side effects include the following.

Common side effects

  • Mild tenderness or bruising at the injection sites, that usually settles over the first few days.

Rare side effects

  • Infection that might require antibiotic treatment. Seek medical help if there is local warmth, redness or soreness at the injection site or you feel hot and unwell.
  • Numbness or weakness in your legs and other areas due to the local anaesthetic spreading. If this happens, the effect is temporary and will get better over minutes or, sometimes, hours.

Very rare side effects

  • Serious nerve injury is extremely rare (less than 1 in 10,000 cases).
  • Injured or collapsed lung (pneumothorax) from injections in the thoracic (chest) area. If you get chest pain or breathlessness, seek immediate medical help.

Asking for your permission (consent)

We want to involve you in decisions about your care and treatment. If you decide to go ahead, you will be asked to sign a consent form. This states that you agree to have the treatment and you understand what it involves.

If you would like more information about our consent process, please speak to a member of staff caring for you.

Before treatment

If your health has changed, it is important to let the doctor know if you:

  • have an infection in your body or on the skin of your back (your doctor will postpone the treatment until the infection is cleared)
  • have started anticoagulant or antiplatelet medicines (blood thinners) such as warfarin, rivaroxaban, heparin or clopidogrel (you might need extra preparation)
  • have any allergies

You must also tell the doctor if there is any chance that you could be pregnant.

If you are planning to fly or travel abroad within 2 weeks after the injections, please let your doctor know, as they might change the date of the injections.

Make sure that you have made arrangements for someone to collect you after the procedure. If you do not, your procedure will probably have to be cancelled. It is unsafe for you to drive immediately after the procedure. If you do, your motor insurance will not be valid.

Bring your glasses if you need them for reading.

Bring a list of all your current medicines, including any you buy from a pharmacy or shop, and any herbal or homeopathic remedies.

Continue to take your medicines as usual on the treatment day (unless your pain doctor or nurse has recommended something different). Please contact us at least 2 weeks before your treatment if you have an infection or are taking antibiotics.

Patients having this treatment do not need to stop taking their blood-thinning medicines.

During treatment

Before the injection, your doctor will discuss the procedure with you. An X-ray machine (or other form of image guidance) will be used to enable accurate injection. Doctors give these injections in slightly different ways, but this is generally what will happen.

  • Observations, such as blood pressure and pulse rate, are taken.
  • A small needle (cannula) might be placed in the back of your hand.
  • You will be carefully positioned and the skin around the injection sites will be cleaned with an antiseptic solution or spray. This can feel very cold.
  • An X-ray machine (or another form of image guidance) will be used to make sure we inject you accurately.
  • You will feel a stinging sensation as local anaesthetic is injected to numb the skin and surrounding tissues. Your doctor will warn you of this first. If you are having sedation (medicine to make you sleep through the procedure) this will not apply.
  • The doctor will direct the needles to the areas suspected to be the source of pain.
  • When the injections are given, you might feel pressure, tightness or a pushing sensation. If there is any discomfort, let the doctor know.

After treatment

You will be taken to a recovery ward where nursing staff will observe and monitor you. You will be told when you can get dressed. You will be given help to make sure that you can stand safely after the procedure.

Your pain will be assessed at rest and during daily activities, such as walking and moving your back, to find out how much pain relief you have immediately after the injections. This will help assess how much of your pain is coming from the facet joints, and help plan future treatments.

Leaving hospital

You can usually leave hospital a few hours after the injections, and sometimes sooner. This will depend on how long your doctor or nurse wants you to stay for in recovery.

You should arrange for someone to be with you as you travel home, and stay with you for 24 hours after your treatment. If this is not possible, you should at least have access to a phone. You should not:

  • drive
  • operate machinery
  • sign legal documents
  • provide childcare unsupervised
  • drink alcohol

If you are unsure, please discuss these issues with your doctor.

You might have some soreness or aching at the injection sites.

Keep the injection sites dry for 24 hours after the procedure.

Do not worry if your pain feels worse for a few days, as this sometimes happens. Take your regular pain killers and medicines as normal and this should settle down. Try to move about the house, but avoid anything too strenuous.

Before you go home you will be given information about who to contact if the pain unit is closed. If it is an emergency, go to your nearest emergency department (A&E) or call 999.

Contact your GP or call NHS 111 if:

  • there is warmth, redness or tenderness at the injection sites
  • you feel hot and unwell

Call 999 for an ambulance if:

  • you get chest pain
  • become breathless

Returning to work

This will be different for everyone, and might depend on the nature of your work. It is difficult to give general advice, so you should discuss this with your doctor.

Follow-up appointments

You will receive a letter with details of a follow-up appointment. It will be a phone call with a nurse specialist or in clinic with a consultant. If you have not heard from us within 10 weeks after the procedure, please contact us, phone 020 7188 4714, 9am to 5pm.


Adapted from information from the Faculty of Pain Medicine of the Royal College of Anaesthetists, and includes contributions from Addenbrooke's Pain Management Unit, the Chronic Pain Service at St Georges Hospital London, Newcastle Pain Management Unit, and the Interventional Specialist Interest of the British Pain Society.

Resource number: 4474/VER2
Date published: May 2023
Review date: May 2026

Contact us

If you have a problem at home, or are worried about your condition, please contact our specialist nurses at the pain management unit.

Phone 020 7188 4714 or 020 7188 8877, 9am to 5pm Monday to Friday, email [email protected]

If it is outside of these hours, please contact your GP or NHS 111.

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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