Effect of radiofrequency use on hip arthroscopy irrigation fluid temperature.

Abstract

The purpose of this study was to determine operating parameters for joint fluid lavage using radiofrequency (RF) in maintaining intra-articular temperatures ≤50°C in the hip joint and to then quantify the influence of flow rate on maintaining safe intra-articular temperatures. Fiberoptic intra-articular thermometers at radial distance intervals of 1, 2, 5, and 10 mm, spanning cross-sectional areas of 3.14, 12.56, 78.5, and 314.1 mm(2), respectively, from the RF probe were used in 3 human hip cadaveric specimens at room temperature, with 9 trials per variable, using a 3-portal technique with a capsule release. Using a new Dyonics RF System continuously at the superior capsulolabral junction for 90 seconds, continuous temperatures were recorded at 50 mm Hg inflow and variable outflow intervals: no flow and 5, 15, and 30 seconds. Lavages were 1 second in duration on suction. Statistical comparison was through multivariate regression analysis and a logistic model. Temperatures reached ≥50°C at 5-mm radial distance from the probe in all but the 5-second pulse lavage group. Elevated temperatures were reached within 1 to 2 seconds locally (1- to 2-mm radial distance) and at a radial distance of 5 mm in the 15-, 30-, and 0-second lavage groups. Logistic regression revealed a reduction in the odds that temperatures ≥50°C will occur as flow frequency increases every 30 (odds ratio = 0.68, P = .086); 15 (odds ratio = -1.22, P = .0067); and 5 (odds ratio = -4.26, P < .0001) seconds. Increasing-interval pulsed irrigation is effective in maintaining intra-articular temperature profiles below 50°C during use of continuous RF ablation. Five-second-interval pulsed lavage is the longest flow interval identified during which fluid 5 mm radially from the RF device never reached temperatures >50°C. Clinical guidelines for using the RF ablation include: meticulous technique, intermittent use, good inflow and outflow, and pulsed lavage at frequent intervals.