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

SummaryObjectiveThe 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 (RFE) and mechanical debridement as a treatment.MethodsPartial 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 RFE probe, and (4) CoVac 50 RFE 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.ResultsThere 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 RFE groups. There were no significant differences in maximum depth and the percentage of dead area between the two RFE treatment groups. Histologic scores demonstrated better cartilage morphology for the control and mechanical debridement groups than those of RFE groups. However, even with full thickness chondrocyte death, the matrix in the RFE treated sections was still retained and the mechanical properties of the treated cartilage did not differ from the mechanical debridement group.ConclusionRFE caused greater chondrocyte death and more severe morphological changes compared to untreated degenerative cartilage and mechanical debridement in this model

Effect of Simulated Shoulder Thermal Capsulorrhaphy Using Radiofrequency Energy on Glenohumeral Fluid Temperature

Purpose: To determine joint fluid temperatures at different time intervals during treatment with radiofrequency energy (RFE) applied in intermittent and continuous treatment manners under flow or no-flow conditions using a simulated shoulder joint model. Type of Study: In vitro measurement of simulated joint fluid temperature during RFE treatment. Methods: A custom-built jig with a chamber (volume size, 25 mL) was used to mimic the adult human shoulder. Three RFE systems: Vulcan EAS plus TAC-S probe (Smith & Nephew Endoscopy, Andover, MA); VAPR II plus End-Effect Electrode (Mitek, Westwood, MA); and ArthroCare 2000 plus TurboVac 90°probe (ArthroCare, Sunnyvale, CA) were tested in the chamber with saline solution initially set at 23°C. Each RFE probe was applied in a paintbrush pattern on the capsular tissue in the chamber and a fluoroptic thermometry probe was placed 1 cm above the RFE treatment probe to record the fluid temperature. Both intermittent and the continuous treatment manners were tested under flow and no-flow conditions. For each probe/manner/flow combination, 6 bovine capsular tissue specimens were tested (n ϭ 6). All data were recorded using a HyperTerminal software program (Hilgraeve Inc, Monroe, MI) into a personal computer. Results: When using intermittent and continuous treatment manners with flow, all recorded chamber fluid temperatures for all tested RFE probes at each time interval were below 40°C. Under no-flow conditions, with intermittent treatment, the ArthroCare probe caused joint fluid temperatures to exceed 50°C after 70 seconds of RFE treatment. With the continuous treatment, the ArthroCare caused chamber fluid temperatures to exceed 65°C after 2 minutes of treatment. The highest mean recorded chamber fluid temperature was caused by ArthroCare probe, which reached 80°C at 3 minutes. For all probes, continuous treatment caused significantly higher chamber fluid temperatures than intermittent treatment. Conclusions: The results of this study indicate that using flow during thermal capsulorrhaphy could lower joint fluid temperature to prevent heated joint fluid from killing chondrocytes of articular cartilage, and the intermittent treatment manner caused lower fluid temperature compared with continuous treatment within the RFE-treated shoulder joint. Clinical Relevance: Articular cartilage of the humeral head may suffer potential thermal injury from heating of joint fluid during RFE thermal capsulorrhaphy