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Assessment of cellular, biochemical, and histologic effects of bipolar radiofrequency treatment of canine articular cartilage

James L. Cook DVM, PhD1, Kevin M. Marberry MD2, Keiichi Kuroki DVM, PhD3, and Keith Kenter MD4
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  • 1 Comparative Orthopaedic Laboratory, University of Missouri, Columbia, MO 65211.
  • | 2 Comparative Orthopaedic Laboratory, University of Missouri, Columbia, MO 65211.
  • | 3 Comparative Orthopaedic Laboratory, University of Missouri, Columbia, MO 65211.
  • | 4 Comparative Orthopaedic Laboratory, University of Missouri, Columbia, MO 65211.

Abstract

Objective—To assess the cellular, biochemical, and histologic effects of bipolar radiofrequency-generated heat on canine articular cartilage.

Sample Population—Articular cartilage explants (n = 72) from 6 canine cadavers and cultured articular chondrocytes from 5 canine cadavers.

Procedure—Cartilage explants were randomly assigned to receive no treatment or treatment with focal (3 seconds) or diffuse bipolar radiofrequency. Following treatment, methylene blue permeability assay was performed (n = 12) and remaining samples (60) were cultured. Immediately and 5, 10, and 20 days after treatment, cultured explants were assessed for glycosaminoglycan (GAG) and collagen contents, type II collagen and matrix metalloproteinase (MMP)-13 immunoreactivity, and modified Mankin histologic scores. Liquid culture media were collected every 4 days and GAG content measured. Additionally, cultured chondrocytes were exposed for 3 seconds to media preheated to 37°, 45°, or 55°C. Cell viability was determined via 2 different assays immediately and 24 hours after treatment.

Results—Radiofrequency-treated cartilage had reduced permeability and considerable histologic damage, compared with control samples; most treated samples had reduced collagen II staining and increased MMP-13 immunostaining. Compared with other treatments, less GAGs were released from cartilage after diffuse radiofrequency treatment throughout the study period. Cell viability was significantly different between controls and cells treated at 55°C immediately and 24 hours after heat treatment.

Conclusions and Clinical Relevance—In this study, bipolar radiofrequency treatment had detrimental effects on normal articular cartilage cells and extracellular matrix with probable long-term clinical consequences. The usefulness of radiofrequency for treatment of osteoarthritic articular cartilage requires further investigation. ( Am J Vet Res 2004;65:604–609)

Abstract

Objective—To assess the cellular, biochemical, and histologic effects of bipolar radiofrequency-generated heat on canine articular cartilage.

Sample Population—Articular cartilage explants (n = 72) from 6 canine cadavers and cultured articular chondrocytes from 5 canine cadavers.

Procedure—Cartilage explants were randomly assigned to receive no treatment or treatment with focal (3 seconds) or diffuse bipolar radiofrequency. Following treatment, methylene blue permeability assay was performed (n = 12) and remaining samples (60) were cultured. Immediately and 5, 10, and 20 days after treatment, cultured explants were assessed for glycosaminoglycan (GAG) and collagen contents, type II collagen and matrix metalloproteinase (MMP)-13 immunoreactivity, and modified Mankin histologic scores. Liquid culture media were collected every 4 days and GAG content measured. Additionally, cultured chondrocytes were exposed for 3 seconds to media preheated to 37°, 45°, or 55°C. Cell viability was determined via 2 different assays immediately and 24 hours after treatment.

Results—Radiofrequency-treated cartilage had reduced permeability and considerable histologic damage, compared with control samples; most treated samples had reduced collagen II staining and increased MMP-13 immunostaining. Compared with other treatments, less GAGs were released from cartilage after diffuse radiofrequency treatment throughout the study period. Cell viability was significantly different between controls and cells treated at 55°C immediately and 24 hours after heat treatment.

Conclusions and Clinical Relevance—In this study, bipolar radiofrequency treatment had detrimental effects on normal articular cartilage cells and extracellular matrix with probable long-term clinical consequences. The usefulness of radiofrequency for treatment of osteoarthritic articular cartilage requires further investigation. ( Am J Vet Res 2004;65:604–609)