Joint denervation for knee and ankle pain

The idea behind it

Joints, including the knee and ankle, are supplied by small articular branches from nearby nerves. These branches carry pain signals from the joint capsule. Partial joint denervation preserves joint function and relieves pain by interrupting the neural pathways that transmit the pain message.^[1] It is one of two joint-preserving ideas described for ankle pain; the other is surgery on painful neuromas.^[2]

Which nerves supply the ankle and knee

The ankle joint capsule is supplied at the front by branches of the saphenous, superficial fibular and deep fibular nerves, on the outer side by the sural and superficial fibular nerves, and on the inner side and back by the saphenous and tibial nerves. Mapping these branches is what makes precise nerve blocks and ablation possible.^[5] The sinus tarsi, a small space on the outer side of the ankle, was studied as part of the ankle’s nerve supply in the same report.^[1] Around the knee, the infrapatellar branch of the saphenous nerve is a common source of front-of-knee pain after surgery; see nerve pain after knee replacement.

Who might be considered

The approach has been described for people who have chronic knee or ankle pain after trauma, a sports injury, a previous arthroscopy or a joint replacement, and who did not respond to standard musculoskeletal treatment, when the joint structure is intact.^[1] It is not a treatment for a joint that is unstable, infected, loose or grossly damaged, where the cause needs its own treatment. Painful neuromas of the joint’s nerves are another situation to consider; see painful neuroma of the foot, ankle and leg.

Testing with a diagnostic block

Before a lasting procedure, a local anaesthetic is placed around the nerves that supply the joint. If pain falls clearly, it suggests the pain travels through those nerves. In one report by the surgeon who developed the approach, 90% of patients whose block reduced their pain score by 5 or more points were expected to get good to excellent relief from partial joint denervation.^[1] This is a single-surgeon report, so it may not apply to everyone. Diagnostic blocks are arranged with another specialist.

The procedures

• Surgical denervation. The nerve branches that carry pain from the joint are identified and interrupted. It has been described as an outpatient, joint-sparing operation that can be free of the need for rehabilitation.^[1]
• Radiofrequency ablation (RFA). A needle is placed near the nerve and heat is used to interrupt the nerve’s signal. This is a needle-based procedure, not an open operation.
• Other ways to interrupt the nerve, such as cryoablation or nerve stimulation, are also reported for the infrapatellar branch.^[6]

What the evidence shows

• Surgical denervation and neuroma surgery around the ankle have been rarely reported and used, but may provide a valuable alternative in selected people with a nerve-related problem.^[2]
• Radiofrequency ablation for knee arthritis. A systematic review of nine studies found 6-month success rates (at least 50% pain relief) of 49% to 74%, with moderate-quality evidence that it reduces knee osteoarthritis pain at six months, and higher success than steroid or hyaluronic acid injections.^[3]
• After knee surgery. A pooled review of 28 studies found that about half of people had at least 50% pain relief at six months (51%). For persistent pain after knee surgery, the evidence was low quality.^[4] A review of painful knee replacements found pain improvement for up to three months with few complications.^[7]

Risks and limits

Risks include numbness in the skin supplied by the nerve, a new painful spot, infection, bleeding, and the possibility that the pain does not improve or returns. Results vary from person to person, and pain can come from other sources than the nerve.

Is it right for you?

The decision depends on the source of your pain and the nerve block result. The first step is an evaluation that excludes structural problems. Dr. Ozturk performs this procedure for appropriate patients, and an evaluation is how to find out whether it fits your situation. Related: neuroma surgery options and nerve decompression.

When to seek care

Consider an evaluation if you have joint pain that follows an injury or joint surgery, burns or shoots, or has not responded to standard care.