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Genicular nerve blocks and radiofrequency

The genicular nerves carry pain signals from the knee joint. Blocking them tests whether they are responsible for your knee pain, and radiofrequency treatment of the same nerves can then provide relief lasting several months to around a year.

Knee osteoarthritis is common and joint replacement is not always the answer — some people are not well enough for surgery, some are on long waiting lists, some do not want it, and a proportion continue to have pain after a technically successful replacement. Targeting the nerves that carry pain from the knee offers an option in all four situations.

How it works. Several small genicular nerves run in predictable positions around the knee, carrying sensory information from the joint. They do not supply muscle, so treating them does not weaken the leg or affect stability.

Diagnostic blocks. A block of the genicular nerves with local anaesthetic, under image guidance, tests whether these nerves are carrying your knee pain. A substantial drop in pain in the hours afterwards makes radiofrequency treatment more likely to help.

Radiofrequency treatment. Where the block is positive, radiofrequency lesions are made at the same targets. Relief commonly lasts somewhere in the range of six to twelve months, with meaningful variation between individuals, and the procedure can be repeated as the nerves regenerate. The evidence base for this in knee osteoarthritis has grown considerably and is reasonably supportive, though study quality varies and reported success rates differ.

What it does not do. It does not slow or reverse arthritis, and it does not change the joint. It reduces the pain signal from a joint that remains as it was. For some people that is enough to defer surgery, exercise more, and sleep better; for others it is a bridge to an operation.

On the day. Performed under X-ray or ultrasound guidance. The block takes 15–20 minutes; radiofrequency takes 30–45 minutes. Light sedation is available for the radiofrequency procedure.

Afterwards. Soreness for one to two weeks is normal. Patches of numbness around the knee are common and usually settle. Full benefit may take four to six weeks to appear.

Risks. Whilst pain procedures are generally safe and well tolerated, all procedures carry risks. The specific risks relevant to you and your procedure will be discussed with you, and written information provided, before you decide to proceed.