Thursday, February 14, 2002
Both monopolar and bipolar radiofrequency energy (RFE) units are used in thermal chondroplasty. According to poster exhibit 491, both types of RFE take at least 15 seconds to contour and completely smooth the chondromalacic cartilage, but using a monopolar RFE unit results in significantly less chondrocyte death.
Researchers used confocal laser microscopy (CLM) and scanning electronic microscopy (SEM) to evaluate both chondrocyte viability and cartilaginous surface smoothing. Because surgeons who are unfamiliar with RFE use variable treatment times, ranging from as little as 2 seconds to as much as 3 minutes, researchers wanted to determine the optimal treatment time. Researchers tested different time intervals, using the manufacturer's recommended settings for both monopolar and bipolar RFE units.
Forty-two fresh osteochondral sections from patients undergoing partial or total knee arthroplasties were used for this study. The sections (Outerbridge grade 2) were divided into two groups, with 36 sections in the test group and 6 sections as untreated controls. Each section in the test group was divided into two distinct treatment regions (1 sq cm each). One region was treated with a bipolar RFE unit and the other region with a monopolar RFE unit.
In addition to testing the monopolar and bipolar RFE units, the researchers also evaluated six treatment time intervals: 5, 10, 15, 20, 30, and 40 seconds (6 specimens/time interval/group). After being treated, each specimen was processed for CLM and SEM.
CLM demonstrated that the depth of chondrocyte death in the monopolar RFE treatment group was significantly less than in the bipolar RFE group at every time interval (p < 0.05). SEM showed that regardless of whether the unit was bipolar RFE or monopolar RFE, it took a minimum of 15 seconds of treatment to contour and smooth the articular surface of the section.
Thermal chondroplasty with RFE units has gained widespread use over the past several years. Currently, more than 10,000 cases are reportedly performed monthly. Based on the results of this research, the most effective and least damaging technique would use a monopolar RFE unit for at least 15 seconds on each square centimeter of treated area.
Researchers included Yan Lu, MD; Mark Merkel, DMV, PhD, Ryland Edwards, DVM, and John Heiner, MD, all of Madison, Wis.; Shane Nho, BA, and Brian Cole, MD, of Chicago, Ill. Funding was provided by Oratec Interventions, Inc.
| 2002 Academy News February 14 Index C |
Last modified 06/February/2002