Pain relief through an antinociceptive effect after radiofrequency application.
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.


OBJECTIVE
Bipolar radiofrequency treatment will ablate nerve fibers, resulting in pain relief.


METHODS
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.


CONCLUSIONS
Bipolar radiofrequency treatment induced acute degeneration and/or ablation of sensory nerve fibers.


CONCLUSIONS
Degeneration or ablation of nerve fibers after bipolar radiofrequency treatment may explain the early postoperative pain relief after microtenotomy for tendinosis.
Takahashi
Norimasa
N
Department of Orthopedic Surgery, University of California, San Diego, La Jolla, California 92093-0630, USA.
Tasto
James P
JP
Ritter
Mark
M
Ochiai
Nobuyasu
N
Ohtori
Seiji
S
Moriya
Hideshige
H
Amiel
David
D
D000818:Animals; D015740:Calcitonin Gene-Related Peptide; D017115:Catheter Ablation; D008297:Male; D009412:Nerve Fibers; D009475:Neurons, Afferent; D009479:Neuropeptides; D009619:Nociceptors; D010146:Pain; D010149:Postoperative Pain / Q000532:radiotherapy*; D051381:Rats; D017207:Rats, Sprague-Dawley; D052256:Tendinopathy
D009479:Neuropeptides; D015740:Calcitonin Gene-Related Peptide