The effect of monopolar radiofrequency energy on partial-thickness defectsof articular cartilage

To evaluate the effect of monopolar radiofrequency (RF) energy on partial-t hickness defects of articular cartilage, comparing the outcome of partial-t hickness defects treated with monopolar RF energy with that of treatment by conversion of partial-thickness defects to full-thickness defects by curet tage and microfracture. Type of Study: Randomized trial using adult female sheep. Materials and Methods: Thirty-six sheep were used in this study. Bot h stifles in each animal were randomly assigned to 1 of the following 3 pro cedures: (1) partial-thickness defect without any treatment to serve as a s ham-operated control, (2) partial-thickness defect with RF energy treatment , and (3) partial-thickness defect treated by conversion of the defect to a full-thickness defect by curettage and microfracture. Nine sheep were euth anized at 0, 2, 12, and 2 1 weeks after surgery (n = 6 per group). After eu thanasia, cartilage samples were harvested from the defect sites, and chond rocyte viability was analyzed by confocal Laser microscopy using a triple-l abeling technique. Cartilage samples also were decalcified and stained with hematoxylin and eosin and safranin-O for histologic analysis. Surface prop erties of cartilage samples were analyzed using scanning electron microscop y. Results: The analysis of chondrocyte viability showed that RF treatment caused death of almost all chondrocytes in the defect. Histologic analysis showed that RF treatment caused detrimental effects to chondrocytes and pro teoglycan concentration that progressed over time, and that full-thickness defects were repaired by fibrocartilage by 24 weeks after surgery. Scanning electron microscopy analysis indicated that RF-treated groups were signifi cantly smoother and less irregular than control groups at 2, 12, and 24 wee ks after surgery. Conclusions: This study showed that monopolar RF energy c aused long-term damage to cartilage in this sheep model and did not appear to have the beneficial effects reported ill a previous study that evaluated application of this technique using a bipolar RF probe.