Radiofrequency Ablation of Genicular Nerves for Chronic Knee Pain
This is a nonsurgical interventional pain procedure performed to help relieve pain and improve function for those with chronic knee pain. This treatment can be an option for those with chronic knee pain who have not improved with conservative care (exercise, physical therapy, medications, corticosteroid injections, viscusupplementation, etc) and either can’t have surgery or do not wish to have a knee surgery. Its also an option for those patients who have had a knee surgery but unfortunately had no improvement of pain. Typically the radiofrequency ablation (RFA) is performed after confirmation of the pain generator by diagnostic genicular nerve blocks. If the diagnostic blocks were positive (meaning there was immediate and significant pain relief after the block) then the RFA would be the next step. If the blocks were negative (meaning no relief at all or minor relief) then the ablation would not be recommended.
What are diagnostic genicular nerve blocks?
Branches of nerves that innervate the knee joint are called genicular nerves. During a diagnostic genicular nerve block an anesthetic is injected under x-ray guidance (sometimes ultrasound) that blocks these nerves interrupting the transmission of the nerve impulse. What this does is “numb” the area that is innervated by the targeted nerve. In this case the knee joint. The nerve will be blocked or “numb” for as long as the anesthetic is active, ranging from 2-3 hours to 6-8 hours depending on which anesthetic is used. During this time period it’s important to know if the pain has been reduced or not because after the anesthetic wears off the effect does not count and the result is not valid. Again, the block is deemed positive if there is immediate and significant pain relief and is deemed negative if there was no relief at all or minor relief.
Typically three genicular nerves are ablated, including the medial superior, medial inferior and lateral superior genicular nerves.
What is an ablation and what is being ablated?
The word ablation means removal or destruction of body tissue. In this case the tissue being destroyed are the genicular nerves. The way these nerves are destroyed (ablated) is by heat generated by radiofrequency waves transmitted by wires inserted through a cannula (type of hollow needle) tip. The tip delivers the heat which ablates the targeted nerves. Ablating these nerves will stop the transmission of pain from the knee joint either stopping or greatly reducing knee pain.
What it does
By destroying the genicular nerves connected to the knee joint the RFA treatment helps treat chronic knee pain. The relief of pain can be complete relief or partial relief depending on the outcome and can last anywhere from 6 to 12 months in duration. The reason that the response is temporary is because with time the genicular nerves will regrow and reconnect to the knee. When the pain comes back, this procedure can be repeated.
What it doesn’t do
The RFA treatment does not heal, treat, or reverse arthritis or any injury to the knee joint. The only benefit is reducing and eliminating chronic constant pain. In that sense the RFA does not “fix the problem” nor has any way of preventing pain from returning in the future. They are strictly meant for alleviating pain from the knee joint. Pain relief is usually 6-12 months in duration.
Then why do it?
Recommended as an option for those with chronic knee pain refractory to conservative care who either can’t have surgery or do not wish to have a knee surgery. Its also an option for those patients who already had a knee surgery but unfortunately had no improvement of pain.
What are the risks?
Overall considered safe when performed with image guidance (like x-ray or ultrasound) by a physician specialized in interventional pain management. Preferably one who is board certified and fellowship trained. Risks include infection, bleeding, allergic reaction, pain aggravation, and nerve injury. In proper setting and under professional care, such risks are very rare.
