What is a Genicular Nerve Block?
A nerve block injection blocks the signals that travel from a nerve supplying a certain part of your body. The genicular nerves supply the knee joint so a genicular nerve block is the nerve block used for knee pain. A nerve block switches off the nerve impulses travelling from your knee to your brain, and this stops your brain from giving you pain in this part of the body. The nerve is blocked temporarily using a local anaesthetic injection. The pain relieving effect of this is usually a few hours. However, sometimes the effect can last for much longer, for weeks or even months.
What is Radiofrequency (RFD) Denervation?
In some cases, it may be possible to do a second procedure to burn the nerve away. This is known as radiofrequency (RFD) denervation, sometimes called rhizotomy or nerve ablation. This may settle the pain for the period of time it takes for the nerve to grow back, which is up to 18 months. However because this is a more invasive procedure with more risks, it is only considered if a nerve block first relieves the pain.
Why have a Genicular Nerve Block or RF denervation?
The aim of a nerve block or RF denervation is to reduce your knee pain, and give you a window of opportunity to improve your quality of life e.g. enable you to increase your activity levels, stay at work, improve your sleep, or reduce your medication.
Are nerve blocks and RF denervation safe?
Nerve blocks and RF denervation are generally a safe form of treatment. However, they can cause side effects, and therefore we will need to know your health history so that, together with you, we can weigh up the risks against the benefits of you having this procedure. We would not usually offer you an injection if you have/are the following:
• Bleeding disorder
• An infection anywhere in your body
• Previous allergic reaction to a local anaesthetic or injection
• Immunosuppressed
• Recent trauma or bruising to the area of the injection
If you are on anticoagulation medication, we will discuss this with you, and depending what you are taking and what it is for, you may need to stop this before the injection.
What are the side effects of nerve blocks and RF denervation?
The nerve block usually uses a local anaesthetic. RF denervation heats the nerve to sever it. Side effects are very rare. They include:
• Allergic reaction/anaphylactic shock with local anaesthetic (extremely rare) – we take all precautions to minimise this risk and treat it should it occur.
• Fainting
• Bleeding/bruising
• Infection – we use a sterile technique to minimise this risk
• Temporary flare-up of pain or numbness, very occasionally palpitations or tremors
• Nerve pain caused by burning nerves (RF denervation only)
• Short term deterioration of muscle tissue or joint surface. Possibly longer term if
injections used repeatedly.
• Pneumothorax (punctured lung) for injections over the rib cage (extremely rare).
• If the nerve supplies another structure as well as the painful one, then this other structure may be affected (see example below).
What should I do after the injection?
You may experience some soreness or aching at the injection site. Please keep the area of the injection dry for 24-hours following the procedure. Do not worry if your pain feels worse for a few days as this sometimes happens. Take your regular pain relief and medications as normal and this should settle down. If steroid was used, this can take up to 2-weeks to take effect on your pain. Following the injection, we advise that you have a day of relative rest, but you can continue with light work and daily activities during this time.
What follow-up will be arranged?
One of the Advanced Practitioners in the pain team will call you 6-8 weeks after your injection to review your response. A member of the Pain Admin team will contact you to arrange this appointment after your injection. We will also send you a post-injection pain questionnaire via text or email to help us better understand the benefits the injection has had on your pain and quality of life.
If having read this information, and discussed any questions or concerns with your clinician, you would like to proceed with an injection, we will ask for your consent. You are free to change your mind after this at any time.