Comparison of mechanical debridement and radiofrequency energy for chondroplasty in an in vivo equine model of partial thickness cartilage injury

Objective: The purpose of this study was to develop a long-term model of cartilage injury that could be used to compare the effects of radiofrequency energy (FIFE) and mechanical debridement as a treatment. Methods: Partial thickness fibrillation of patellar cartilage was created in 16 mature ponies. Three months after the initial surgery all injured patellae were randomly selected to receive one of the four treatments (n = 8/treatment): (1) control, (2) mechanical debridement with a motorized shaver, (3) TAC-CII FIFE probe, and (4) CoVac 50 FIFE probe. The ponies were euthanized 22 months after treatment. Macroscopic appearance of the cartilage surface was scored, vital cell staining was used to determine chondrocyte viability and light microscopy was used to grade the morphometric changes within the cartilage. Mechanical properties (aggregate modulus, Poisson's ratio and permeability) also were determined and compared to normal uninjured cartilage. Results: There were no differences in the cartilage surface scores among the treatment groups and control samples (P> 0.05). The maximum depth of cell death and the percentage of dead area in control and mechanical debridement groups were significantly less than those in both FIFE groups. There were no significant differences in maximum depth and the percentage of dead area between the two FIFE treatment groups. Histologic scores demonstrated better cartilage morphology for the control and mechanical debridement groups than those of FIFE groups. However, even with full thickness chondrocyte death, the matrix in the FIFE treated sections was still retained and the mechanical properties of the treated cartilage did not differ from the mechanical debridement group. Conclusion: FIFE caused greater chondrocyte death and more severe morphological changes compared to untreated degenerative cartilage and mechanical debridement in this model. (C) 2006 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.