Nerve regeneration after radiofrequency application

Background: Many patients with chronic tendinosis have experienced early pain relief after application of bipolar radiofrequency treatment. It is hypothesized that the mechanism of action may be the acute degeneration and/or ablation of sensory nerve fibers. Hypothesis: After ablation or degeneration by bipolar radiofrequency, nerve fibers will have the ability to regenerate with time. Study Design: Controlled laboratory study. Methods: Eighteen Sprague-Dawley rats were used in this study. These rats were divided into 3 groups (30, 60, and 90 days after bipolar radiofrequency). These rats were treated with 2 points of bipolar radiofrequency applications to the left hindpaws with the Topaz microdebrider device. Right hindpaws were used as the contralateral control. Tissues were processed for neural class III beta-tubulin or calcitonin gene-related peptide immunohistochemistry by using the free-floating avidin biotin complex technique. The numbers of neural class III P-tubulin-immunoreactive and calcitonin gene-related peptide-immunoreactive nerve fibers in the epidermis were counted and compared with those in the contralateral control. Results: Although the numbers of nerve fibers demonstrated by both the antibodies of neural class III P-tubulin and calcitonin gene-related peptide were significantly decreased (P <.0001) until 60 days after bipolar radiofrequency treatment, regeneration of the epidermal nerve fibers occurred 90 days after treatment. Conclusion: Bipolar radiofrequency treatment induced degeneration of sensory nerve fibers immediately after treatment, but by 90 days posttreatment, there was evidence of complete regeneration. Clinical Relevance: Early degeneration followed by later regeneration of nerve fibers after bipolar radiofrequency treatment may explain long-term postoperative pain relief after microtenotomy for tendinosis.