Thermal radiofrequency ablation of the saphenous nerve in dogs with pain from naturally-occurring stifle osteoarthritis

In a recent paper, we describe a potential method for thermal radiofrequency (TRF) for ablation of the saphenous nerve with a view to developing a technique that may provide analgesia for dogs with intractable stifle osteoarthritis ( ). We showed that TRF could produce lesions in target nerves similar to those reported in humans undergoing therapeutic denervation. Safety was not demonstrated in dogs with naturally-occurring pain, and neither was efficacy proven. The purpose of this letter is to urge extreme caution in applying this technique. Although TRF ablation has provided pain relief in clinical canine patients, the owners of two dogs enrolled in a clinical trial of saphenous TRF ablation have reported substantial worsening of the signs associated with stifle pain; in one dog, pain worsened for a month before improving markedly at 3 months, and a second dog is currently undergoing treatment for increased pain. These adverse responses could be transient neuropathic pain, as has been described in humans after radiofrequency denervation of the third occipital nerve ( ). However, other possible causes cannot be ruled out including neuritis, thermal damage to non-target tissues, failure of the TRF accompanied by natural progression of the osteoarthritis, anatomical variability or other technical problems. Investigation of TRF of the saphenous nerve in clinical canine patients is ongoing.