Surface alterations and chondrocyte activity in articular cartilage after monopolar radiofrequency treatment

Osteoarthritis is characterized by progressive degeneration of articular cartilage and impaired joint function. Arthroscopic monopolar radiofrequency energy chondroplasty enables minimally invasive smoothing of damaged cartilage surfaces, but there are concerns about chondrocyte viability under thermal stress, which is particularly critical in the wrist because of the thin cartilage layers and complex joint anatomy.

In this in vitro study, porcine tibial plateau cartilage with simulated Outerbridge grade III degeneration was treated using six monopolar radiofrequency energy application protocols, including continuous or pulsed modes with single or double passes. Subchondral temperature was recorded, surface roughness was quantified by confocal laser scanning microscopy using the root-mean-square parameter and chondrocyte viability was assessed using live/dead and caspase 3/7 assays.

Subchondral temperatures remained below physiological core body temperature in all treatment groups. All radiofrequency energy protocols resulted in a clear reduction of surface roughness compared with degenerated control cartilage. The greatest smoothing effect was observed following a single pulsed application with longer activation intervals, although this also caused extensive chondrocyte death. Shorter pulsed application intervals produced moderate surface smoothing while preserving comparatively higher chondrocyte viability.

Monopolar radiofrequency energy chondroplasty effectively reduces cartilage surface roughness but is associated with substantial chondrocyte loss regardless of the application protocol. Among the tested approaches, pulsed energy delivery with short activation intervals provided the most favourable balance between surface smoothing and cell preservation. However, the in vivo safety of this approach remains uncertain, particularly when applied to thin cartilage layers such as those in the wrist.