Background: Many patients with chronic tendinosis have experienced early pain relief after application of bipolar radiofrequency treatment. Pathologic nerve ingrowth or nerve irritation in the tendon has been considered as a possible cause of the pain experienced with tendinosis.
Hypothesis: Bipolar radiofrequency treatment will ablate nerve fibers, resulting in pain relief.
Study design: Controlled laboratory study.
Methods: Eighteen Sprague-Dawley rats were used in this study. Eight rats were treated with 2 points of bipolar radiofrequency applications applied to the hind paws with the Topaz microdebrider device, 6 sham rats had a needle applied to the hind paws, and there were 4 control rats. Tissues were processed for neural class III beta-tubulin (TUJ-1) or calcitonin gene-related peptide (CGRP) immunohistochemistry by using the free-floating avidin-biotin complex technique. The numbers of TUJ1-immunoreactive and CGRP-immunoreactive nerve fibers in the epidermis were counted and compared with sham and control.
Results: The number of nerve fibers demonstrated by both the antibodies of TUJ1 and CGRP were significantly decreased (P = .0002-.002) during the first 2 weeks after bipolar radiofrequency treatment. Macroscopically, the foot pad showed 2 dimples on the surface after bipolar radiofrequency treatment. Although it still showed a scar after 7 days, after 14 days it looked no different than the untreated contralateral control foot pad and foot pad of the sham group.
Conclusion: Bipolar radiofrequency treatment induced acute degeneration and/or ablation of sensory nerve fibers.
Clinical relevance: Degeneration or ablation of nerve fibers after bipolar radiofrequency treatment may explain the early postoperative pain relief after microtenotomy for tendinosis.