Effects of monopolar radiofrequency heating on intradiscal pressure in sheep

BACKGROUND CONTEXT: No previous study has assessed the effect of monopolar rachofrequency (RF) heating on intradiscal pressure. PURPOSE: To determine the decrease in lumbar intradiscal pressure after monopolar RF heating. STUDY DESIGN/SETTING: Intradiscal pressure was measured in sheep lumbar discs treated with monopolar RF heating. METHODS: Two monopolar RF heat treatments at 90 degrees C were applied for 2 minutes each to lumbar intervertebral discs of sheep. Intradiscal pressure was measured in live sheep at 0, 7, 14, 2 1, and 28 days posttreatment. Pressure measurements were taken with a microtip pressure transducer. Electrodes were inserted but not activated in separate discs as a sham control. In vitro sheep spine of different age groups, loading conditions, and electrode orientations were similarly heat treated and intradiscal pressures were measured. RESULTS: Intradiscal pressure was significantly reduced I week after monopolar RF heating and remained stable through the 4-week observation period. The RF electrode orientation, the age, and the type of disc loading have significant effects on the amount of initial intradiscal pressure reduction. CONCLUSIONS: Monopolar RF heating can reduce intradiscal pressure in the lumbar spine of sheep. (c) 2007 Elsevier Inc. All rights reserved.