Document Title: Kaab-AJSM-Oct05.shtml
Article Title: Monopolar Radiofrequency Treatment of Partial-Thickness Cartilage Defects in the Sheep Knee Joint Leads to Extended Cartilage Injury
Authors: Max J. Kaab, MD, PhD, Herman J. Bail, MD, Andreas Rotter, Pierre Mainil-Varlet, MD, PhD, Iolo Gwynn, PhD and Andreas Weiler, MD, PhD
Publication: American Journal of Sports Medicine, Baltimore, Maryland
Date: October 2005
Volume 33, pages 1472-1478
Keywords: thermal shrinkage, articular-cartilage defects, long-term damage, heat-induced damage, chondrocyte death, necrosis, predisposition to osteoarthritis, articular-cartilage deterioration due to thermal injury, radiofrequency (RF) energy, partial-thickness articular-cartilage defect, confocal optical microscopy.

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Comments: The authors found that cartilage thermal shrinkage (just as it is harmful in the context of damaged knee ligaments) has no place in the realm of articular-cartilage defect repairs. They note that radiofrequency-induced damage can still be detected at 6 months post-operative; this damage probably persists well beyond this time frame. The authors found that irregular fronds of articular cartilage, a hallmark of chondromalacia, are aesthetically unpleasing but often represent viable articular cartilage. Reshaping everything with a thermal wand may make it look nicer, but will destroy its viability. (Doctors who still believe in the orthopedic use of thermal shrinkage might do well to be reminded that the thin layer of articular cartilage which covers the articulating bony surfaces is very different from the flat tar-and-gravel roofs typically found on commercial office buildings. Tar-and-gravel roofs can, in certain circumstances, be repaired by heating and smoothing out of the tar. Radiofrequency thermal shrinkage of cartilage attempts to do exactly this, yet with cartilage inside the human body. It does not work! So, the doctor might wish to consider donating his/her themal-shrinkage wand to a local roofing company.)

ABSTRACT

Background: The application of radiofrequency energy to smooth and stabilize the cartilage surface has become increasingly controversial. There is little knowledge on extended-term effects, such as cartilage viability.

Purpose: To analyze the effect of radiofrequency treatment on artificially created partial-thickness defects in the femoral cartilage of sheep knee joints 24 weeks after surgery.

Study Design: Controlled laboratory study.

Methods: Grade II cartilage surface defects on the medial and lateral femoral condyles were artificially created in sheep for in vivo analysis. The cartilage lesions were treated alternately on the lateral or the medial condyle using a monopolar radiofrequency probe. Radiofrequency treatment was performed in a freehand technique until surface smoothing without change of cartilage color was seen. At 24 weeks after surgery, cartilage samples were harvested and were processed for macroscopic and histological evaluation. To analyze the effect of radiofrequency at time zero, samples of sheep femoral condyle cartilage with and without artificially created clefts were treated in vitro with radiofrequency. Evaluation was performed by scanning electron and confocal microscopy.

Results: At 24 weeks after surgery, grade IV cartilage defects were detected in all radiofrequency-treated samples. The histological findings showed a central ulcer and dead chondrocytes in the radiofrequency-treated regions. The radiofrequency-treated cartilage revealed partial surface irregularities with partial-defect repair. After radiofrequency treatment in vitro, samples at time zero showed smoothing of the artificially created clefts, as seen by scanning electron microscopy. Confocal microscopy showed necrosis of chondrocytes over approximately one fourth of the upper cartilage thickness.

Conclusion: Even if chondrocyte death is seen only in approximately one fourth of the upper cartilage layers in the sheep femur after in vitro application, radiofrequency treatment can cause damage to cartilage 24 weeks after application.

Clinical Relevance: Caution is recommended in the application of monopolar radiofrequency energy by visual control to partial-thickness cartilage defects. Irregular fronds of chondromalacia may be unattractive but represent viable articular cartilage. Using radiofrequency to obtain a more visually pleasing smooth surface may be counterproductive.

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