Effect of bipolar radiofrequency energy on human articular cartilage. Comparison of confocal laser microscopy and light microscopy.

PURPOSE To evaluate chondrocyte viability using confocal laser microscopy (CLM) following exposure to bipolar radiofrequency energy (bRFE) and to contrast CLM with standard light microscopy (LM) techniques. TYPE OF STUDY In vitro analysis using chondromalacic human cartilage. METHODS Twelve fresh chondral specimens were treated with the ArthroCare 2000 bRFE system (ArthroCare, Sunnyvale, CA) coupled with 1 of 2 types of probes and at 3 energy delivery settings (S2, S4, S6). A sham-operated group was treated with no energy delivered. Specimens were analyzed for chondrocyte viability and chondral morphology with CLM using fluorescent vital cell staining and with LM using H&E and safranin-O staining. RESULTS LM with H&E staining showed smoothing of fine fronds of fibrillated cartilage; thickened fronds were minimally modified. Chondrocyte nuclei were present and not morphologically different than nuclei within sham-operated and adjacent untreated regions. LM with safranin-O staining showed a clear demarcation between treated and untreated regions. CLM, however, showed chondrocyte death: the depth and width of chondrocyte death increased with increasing bRFE settings. CONCLUSIONS CLM showed that bRFE delivered through the probes investigated created significant chondrocyte death. These changes were not apparent using LM techniques.