title: The effects of monopolar radiofrequency energy on intact and lacerated ovine menisci.
abstract: OBJECTIVE
  To evaluate the effect of monopolar radiofrequency energy (RFE) on intact and lacerated meniscal tissue.
  
  
  METHODS
  In vitro study. Application of monopolar RFE to soft tissue for treatment of various musculoskeletal disorders has been explored recently, although its effect on meniscal tissue has not been critically evaluated. Monopolar RFE denatures and fuses collagen. Given that menisci are composed primarily of type I collagen, we proposed that RFE could be applied to meniscal tears with minimal effect on healthy meniscal tissue.
  
  
  METHODS
  Adult sheep menisci were given 1 of 2 treatments (65 degrees C, 15 W or 75 degrees C, 10 W) with a monopolar RFE generator. Specimens were processed for scanning electron microscopy (SEM), transmission electron microscopy (TEM), light microscopy, and confocal laser microscopy. A computer-based area-determination program was used to calculate the treated area in confocal laser images.
  
  
  RESULTS
  SEM changes in treated tissue consisted of surface smoothing with collagen fibril fusion. Changes apparent with TEM included tissue homogenization with loss of cross-striations and fusion of collagen fibrils. Histologic changes consisted of fusion and loss of collagen fiber individualization, pyknosis of fibrochondrocyte nuclei, and loss of lacunae surrounding fibrochondrocytes. There were clear demarcations between treated and untreated tissue with both treatments. There were no discernible differences between treatment groups on SEM, TEM, or histologic examination. Confocal laser microscopic evaluations showed distinct treatment areas. The mean area affected ranged from 6.6% for 65 degrees C, 15 W to 8.8% for 75 degrees C, 10 W.
  
  
  CONCLUSIONS
  The primary effects of monopolar RFE treatment of menisci in this study were consistent with thermal tissue damage limited to the treatment area. Monopolar RFE treatment of a meniscal laceration may stabilize the tear by fusing collagenous tissue in the surrounding area and prevent propagation along tissue lines. This study presents preliminary in vitro results. Further studies are necessary before clinical applications can be recommended.
authors.affiliation: Comparative Orthopaedic Research Laboratory, School of Veterinary Medicine, The University of Wisconsin, Madison, Wisconsin 53706, U.S.A.
authors.forename: M J
authors.initials: MJ
authors.lastname: Lopez
authors.forename: L A
authors.initials: LA
authors.lastname: DeTemple
authors.forename: Y
authors.initials: Y
authors.lastname: Lu
authors.forename: M D
authors.initials: MD
authors.lastname: Markel
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D003094:Collagen / Q000648:ultrastructure; D066298:In Vitro Techniques; D008592:Menisci, Tibial / Q000473:pathology / Q000601:surgery*; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D012756:Sheep; D000070600:Tibial Meniscus Injuries
chemical_list: D003094:Collagen