Monopolar Radiofrequency Energy Effects on Joint Capsular Tissue: Potential Treatment for Joint Instability An In Vivo Mechanical, Morphological, and Biochemical Study Using an Ovine Model

The purpose of this study was to evaluate the thermal effect of monopolar radiofrequency energy, a potential treatment means for joint instability, on the mechanical, morphologic, and biochemical properties of joint capsular tissue in an in vivo ovine model. The energy was applied arthroscopically to the synovial surface of the femoropatellar joint capsule of 24 sheep. The sheep were sacrificed at 0, 2, 6, and 12 weeks after surgery (6 per group). Monopolar radiofrequency energy initially caused a significant decrease in tissue stiffness and an increase in tissue relaxation properties, followed by gradual improvement in the tissue's mechanical properties by 6 weeks after surgery. Microscopic examination illustrated that radiofrequency energy initially caused collagen hyalinization and cell necrosis, followed by active tissue repair. Biochemical analysis revealed that treated collagen was significantly more trypsin-susceptibile than untreated collagen at 0 and 2 weeks after surgery, indicating early collag...