What is a genicular nerve diagnostic Intervention?

A diagnostic injection is carried out to assess the benefit gained by the local anaesthetic injection to the Genicular nerves.  If this gives meaningful benefit then we may proceed to carry out a denervation to the Genicular nerves.

What is a genicular nerve denervation?

A denervation (neurotomy) is a procedure that aims to change the way pain is transmitted from the nerves to the brain.  The nerve is interrupted by heating / cauterising it with an electrical current from a special device, called a radio-frequency machine.  By selectively applying radio frequency to the nerves (genicular nerves) surrounding the knee, one can effectively relieve pain in the knee more long term than the diagnostic intervention.  You will be offered this intervention if you have received good benefit from a diagnostic Genicular nerve block.

Benefits

Pain relief for a period of time, which for some can last up to a period of 2 years.

Risks

Unfortunately, no pain procedure can be risk free.  There are also no guarantees that this procedure will relieve your pain.

Common short-term side effects include:

  • Increased pain and discomfort at the site of the injection which may last up to three weeks
  • Infection, bruising and bleeding
  • There is a possibility that you may have an allergic reaction to the drugs used
  • The procedure can cause some numbness in the knees. This is temporary and will usually resolve
  • Not helpful in reducing your pain.

Long-term effects are uncommon and include:

  • The possibility of a sustained increase in pain
  • The possibility of permanent neurological problems such as persisting numbness and weakness.
If you become unwell prior to your admission or find out that you are pregnant, please make contact with us urgently as we may need to postpone your intervention.

  • You will have the treatment as a day case on our Day Case Unit (SAPU)
  • You should arrange for someone to drive you home after your injection
  • Your length of stay may vary, but you will be d/c on the same day as your admission
  • Please bring a list of your current medications with you
  • You will be asked to undress and put on a theatre gown. You can keep your underwear on
  • Your doctor will discuss the procedure with you and ask you to sign a consent form. As the procedure involves the use of X-rays female patients will be asked for details of their last menstrual period. If there is any possibility that you may be pregnant, please inform the doctor or nurse.

  • The procedure will be carried out under fluoroscopic or ultrasound guidance.  This allows the doctor to identify the specific nerves to be treated
  • Once you are lying in the correct position the doctor will clean your knee with an antiseptic solution which may feel cold
  • A local anaesthetic is injected at the site of the procedure. This may sting initially, before the skin goes numb Four injections are given, three above and one below your knee joint
  • This intervention can be carried out with or without the use of steroids, your consultant will discuss this with you on the day
  • It important that you keep still during the procedure as a special hollow needle will be carefully inserted under Fluoroscopic or ultrasound control into the correct position. Three needles are used for this procedure, which may be quite uncomfortable during insertion. A very thin wire will then be threaded down the needle
  • A small dressing will be placed over the injection sites.  This can be removed in the evening.

If you are having the Radiofrequency Intervention the below will also happen

  • The doctor may ask you to say when you can feel a mild pain in your knee or a twitch in your foot as the machine settings are adjusted. This is very important as it makes sure that the tip of the needle is in the right place
  • The machine settings will then be set to cauterise/ burn the nerve by heating it for about a minute. During this period, you may experience some pain at the site of the procedure
  • A self-adhesive foil plate will be placed on your body; this is connected to the radiofrequency machine to make an electric circuit.

  • After the procedure you will be taken to an area to recover
  • The nursing staff will observe you before going home
  • Please be careful when you first get off the trolley – ensure you are steady on your feet
  • You will be discharged when your Doctor is happy that you are fit to leave.

  • Take your regular medication and painkillers as normal
  • There may be an initial increase in discomfort before you start to experience pain relief.  During this period, you may need to increase your painkillers or require stronger painkillers.  Please see your GP if your current pain killers are not working
  • You will be followed up via the a telephone clinic with one of the Clinical nurse specialist, or your consultant following this intervention.

Please ensure that you have arranged for someone to drive you home after this procedure

If you have any urgent concerns following this intervention, please contact your local urgent healthcare services

You can also leave a message on the clinical nurse specialist helpline number on 020 8909 5669 if your query is not related to a medical emergency

The information in this leaflet is not intended to replace your doctor's advice.  If you require more information or have any questions, please speak to your doctor prior to the consent for the procedure. 

Printing of this document is only valid on the day printed, please refer to the website for most up to date information:

https://www.rnoh.nhs.uk/patients-and-visitors/patient-information-guides/patients-guide-genicular-nerve-knee-diagnostic-intervention-and-denervation-intervention

Page last updated: 27 January 2025

Review due: 01 January 2027