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Synopsis: Bipolar radiofrequency energy was shown to create a large zone of chondrocyte death within articular cartilage that was not evident on light microscopy.
Source: Lu Y, et al. Effect of bipolar radiofrequency energy on human articular cartilage: Comparison of confocal laser microscopy and light microscopy. Arthroscopy. 2001;17(2): 117-123.
Radiofrequency probes, both monopolar and bipolar, have rapidly gained acceptance among orthopaedic surgeons. Although initially developed for soft tissue shrinkage applications, they have been advocated for treatment of fibrillated articular cartilage despite the absence of objective clinical studies that document an advantage over conventional debridement with a shaver. More importantly, studies evaluating their effect on chondrocytes are few, and initial studies used only light microscopy to assess chondrocyte viability.1,2
Lu and colleagues have now published their third study that demonstrates chondrocyte death with radiofrequency energy. Using fresh, human, osteochondral specimens obtained during knee replacement surgery, Lu et al waved the bipolar radiofrequency probe (ArthroCare) over a 3-second interval just above the chondral surface in an arthroscopic environment. Specimens were then analyzed using a fluorescent vital cell staining technique that is sensitive and accurate for chondrocyte viability. Confocal laser microscopy detects live cells as green and dead cells as red. This was compared to conventional light microscopy.
They found that radiofrequency killed a large zone of chondrocytes proportionate to the temperature setting and sometimes all the way to subchondral bone. All settings killed chondrocytes to a much greater degree than would be seen with mechanical shaving. Light microscopy could not detect chondrocyte death, as the cells visually appeared normal at the time of treatment. They concluded that light microscopy gives a false impression of cell viability and that radiofrequency kills an alarmingly high number of chondrocytes surrounding the treated area.
Heat kills. Make no mistake. Lu et al are to be congratulated for giving us objective data that demonstrate that these new radiofrequency probes are not to be used on articular cartilage. Anyone doubting this should look at the impressive figures in this paper showing a large zone of red-cell death that looks like an expanding mushroom cloud. Although energy settings correlated with the size of the zone of death, it was unacceptably large in all cases. Interestingly, one of the companies manufacturing competing devices funded this study (Oratec), indirectly making the data all the more believable. We need to understand that this technology delivers heat upward of 100-160°C to the surface while chondrocytes die at about 50°C.
I must admit that I jumped on board with this technology when it first became available. Visually, the surface is smoothed in an attractive way. However, as Lu et al demonstrate well, there is more to this than meets the eye (or the microscope). Those chondrocytes beneath the surface are dead, yet trapped within the matrix. Over time, the matrix will deteriorate, as cells do not support it. I have seen this on second look arthroscopy with dramatic loss of articular cartilage evident at about 1 year or so. Needless to say, I no longer use radiofrequency on the joint surface. I think the message in this paper needs to get out to surgeons. Radiofrequency has its place, just not on the joint surface.
1. Kaplan L, et al. The acute effects of radiofrequency energy in articular cartilage: An in vitro study. Arthroscopy. 2000;16:2-5.
2. Turner AS, et al. Radiofrequency (electrosurgical) ablation of articular cartilage: A study in sheep. Arthroscopy. 1998;14:585-591.