Experimental Study On Effect Of Bipolar Radiofrequency Energy Treatment Time On Chondrocyte Viabillity And Surface Contouring

【Objective】Articular cartilage defects are secondary to acute trauma or as the result of joint degeneration,its incidence is increasing year by year. The partial-thickness defects have been identified to play a relevant role in cartilage degeneration,not many successful attempts have been made to treat these defects to prevent further cartilage damage. More recently,radiofrequency energy devices have been used to treat articular cartilage defects.This procedure is claimed to provide a smooth and stable articular surface and to prevent further degeneration by shrinking or removing fibrillated collagenous tissues. There is debate about the advantage and disadvantage of using RFE to treat articular cartilage defects, present many dilemmas to the orthopedists. The purpose of this study was to evaluate chondrocyte viability through HE staining and the release ratio of GAG ,and surface contouring of articular cartilage using SEM respectively, during different treatment time with bRFE.Our aim was to provide helpful information to clinicians who use RFE to treat articular cartilage defects.【Methods】Three fresh bovine knee served as the experimental specimens for the study.Each knee joint was exposed under sterile conditions using a medial parapatellar arthrotomy. Using a surgical marker pen,grids consisting of 6(3×2)1-cm2 boxes were created on the medial and lateral femoral condyles to demarcate the treatment areas, then articular cartilage defects were created in normal bovine cartilage using bone rasp. The distal femur was then isolated and submerged in a large sterile basin filled with moderate normal saline at a room temperature. Under arthroscopic visualization, bRFE was used to treat the articular surface with the different treatment time according to clinical treatment mode. One served as the control while the others were treated for 10,20,30,40 and 50 seconds respectively.Full-thickness articular cartilage was then harvested from the treatment areas. Each of sample was divide into three parts averagely .Twelve sample per treatment time were then assessed for chondrocyte morphology and viability through HE staining(n=6) and measuring the release rate of GAG(n=6) respectly ;six sample per treatment time were then assessed for the surface contouring of articular cartilage using SEM;and eighteen additional untreated samples were obtained serve as the controls.【Results】1,HE image demonstrates the number of empty lacuna increased and the density of chondrocyte decreased at different zone with treatment time increasing.The chondrocyte viability was correlated with the treatment time negatively,the release ratio of GAG declines with the increase of treatment time;GAG release ratio decrease obviously when treatment time is more than 10 seconds.No significant differences in GAG release ratio of cartilage were found between 40 second group and 50 second group(P>0.05).There were significant differences in GAG release ratio of cartilage between groups(P<0.05).2,Degrees of articular cartilage smoothness was correlated with the treatment time positively,the score of cartilage surface increases with the increase of treatment time; SEM showed that bRFE required more than 20 seconds to smooth the cartilage surface sufficiently to reach the SEM score of 2.The SEM scores for 20 second group and longer treatment time group were significantly higher than those for 10 second group and control group.No significant differences in SEM scores were found between 40 second group and 50 second group, between 40 second group and 50 second group(P>0.05).There were significant differences in SEM scores of cartilage surface between groups(P<0.05).【Conclusion】When bRFE treat the injured articular cartilage,chondrocyte viability and degrees of articular cartilage smoothness were associated with the treatment time.