Thermal chondroplasty with radiofrequency energy - An in vitro comparison of bipolar and monopolar radiofrequency devices

The purpose of this study was to examine the in vitro effects of three radi ofrequency energy devices (two bipolar devices and one monopolar device) fo r the performance of thermal chondroplasty. Thirty-two fresh bovine femoral osteochondral sections (approximately 3 x 4 x 5 cm) from eight cows were d ivided into four groups (three treatment patterns and one sham-operated gro up with eight specimens per group). The three treatment patterns consisted of 1) radiofrequency energy delivered by a mechanical jig at 1 mm/sec in a contact mode (50 g of pressure), 2) radiofrequency energy delivered by a me chanical jig at 1 mm/sec in a noncontact mode (1 mm between probe tip and a rticular cartilage surface), and 3) radiofrequency energy smoothing of abra ded cartilage during arthroscopic visualization. Thermal smoothing of the a braded cartilage surface was accomplished with all three devices. Significa nt chondrocyte death, as determined by confocal laser microscopy and cell v iability staining, was observed with each device. The bipolar radiofrequenc y systems penetrated 78% to 92% deeper than the monopolar system. The bipol ar systems penetrated to the level of the subchondral bone in ail osteochon dral sections during arthroscopically guided paintbrush pattern treatment. Radiofrequency energy should not be used for thermal chondroplasty until fu rther work can establish consistent methods for limiting the depth of chond rocyte death while still achieving a smooth articular surface.