Subacromial temperature profile during bipolar radiofrequency use in shoulder arthroscopy. Comparison of Coblation® vs. VAPR®.


BACKGROUND The use of bipolar electrodes for arthroscopic procedures carries a theoretical ex vivo risk of inducing burn injuries. Few studies have measured the in vivo temperatures produced by bipolar electrodes during arthroscopy, and their results are conflicting. The objective of this study was to evaluate the temperature profile within the subacromial space during shoulder arthroscopy with two different electrode systems. HYPOTHESIS The primary hypothesis was that the two electrode systems produced similar temperature variations and peak temperatures. The secondary hypothesis was that neither electrode system produced irrigation-fluid temperatures above the tissue-damage threshold. MATERIAL AND METHODS A comparative, prospective, single-centre, single-surgeon, single-blind study was conducted to compare the Coblation® system (Smith&Nephew, Andover, MA, USA) and the VAPR® system (DePuy Synthes Mitek Sports Medicine, Raynham, MA, USA) in 13 patients undergoing shoulder arthroscopy. A temperature probe inserted into the subacromial space was used to record temperatures at 10-second intervals for 60seconds during continuous radiofrequency application. RESULTS Mean baseline temperature was 21.4±0.7°C with VAPR® and 23.0±2.2°C with Coblation®. No significant between-group differences were found during the first 40seconds. The mean peak temperature reached after 60seconds was 25.0±1.9°C with VAPR® and 27.9±2.8°C with Coblation® (P<0.05). DISCUSSION Few studies have compared the in vivo temperatures produced during arthroscopy by different electrode systems. In vivo studies have established that temperature increases can cause tissue damage, particularly to chondrocytes, and that the irrigation flow rate plays a key role in lowering the in vivo temperatures. Our study showed a significant difference between the two electrode systems after 50seconds of use, with lower temperatures with the VAPR®. Nevertheless, neither system increased the irrigation-fluid temperatures above the tissue-damage threshold. Both systems can be used safely, provided the manufacturer instructions are followed and the irrigation system is effective. LEVEL OF EVIDENCE II (prospective randomized trial).


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