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 con trast 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 (Arth roCare, 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 e nergy delivered. Specimens were analyzed for chondrocyte viability and chon dral 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 smo othing of fine fronds of fibrillated cartilage; thickened fronds were minim ally modified. Chondrocyte nuclei were present and not morphologically diff erent than nuclei within sham-operated and adjacent untreated regions. LM w ith safranin-O staining showed a clear demarcation between treated and untr eated 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 sign ificant chondrocyte death. These changes were not apparent using LM techniq ues.