title: Mechanical and biochemical effect of monopolar radiofrequency energy on human articular cartilage: an in vitro study.
abstract: BACKGROUND
  There are growing concerns about thermal chondroplasty using radiofrequency energy to treat partial-thickness cartilage defects. However, most studies emphasize effects on chondrocyte viability, and other factors such as mechanical properties are less studied.
  
  
  OBJECTIVE
  Radiofrequency energy may cause significant effects on articular cartilage other than chondrocyte viability.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Human osteoarthritic cartilage samples were obtained from total knee arthroplasty, and monopolar radiofrequency energy was applied using commercially available equipment. Material properties (compressive stiffness, surface roughness, and thickness) just before and after thermal treatment were determined using ultrasound. A series of biochemical analyses were also performed after explant culture of the samples.
  
  
  RESULTS
  The cartilage surface became smoother by radiofrequency energy, whereas cartilage stiffness or thickness was not altered significantly. Collagen fibrils, especially in the superficial layers, were converted to denatured form, whereas proteoglycan contents released in the media as well as retained in the tissue remained unchanged. The concentrations of matrix metalloproteinases (MMP-1 and MMP-2) were reduced remarkably.
  
  
  CONCLUSIONS
  Radiofrequency energy is able to create a smooth cartilage surface and reduce catabolic enzymes at the cost of collagen denaturation and chondrocyte death in the superficial layers. The stiffness of the cartilage is not changed at time zero.
  
  
  CONCLUSIONS
  Further animal as well as clinical studies will be necessary to fully evaluate the long-term effects of radiofrequency energy.
authors: Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Kawahara-Cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
authors: Ko
authors: K
authors: Yasura
authors: Yasuaki
authors: Y
authors: Nakagawa
authors: Masahiko
authors: M
authors: Kobayashi
authors: Hiroshi
authors: H
authors: Kuroki
authors: Takashi
authors: T
authors: Nakamura