The effect of monopolar radiofrequency treatment pattern on joint capsularhealing - In vitro and in vivo studies using an ovine model

The purpose of this study was to compare joint capsular healing after two d elivery patterns of monopolar radiofrequency energy: 1) uniform treatment o f the joint capsule (paintbrush pattern) and 2) multiple single linear pass es (grid pattern). First, an in vitro study was performed to compare the pe rcent shrinkage of these two treatment patterns using the femoropatellar jo ints (stifles) of six sheep. Monopolar radiofrequency energy (settings, 70 degreesC/15W) was applied to the lateral joint capsule; the treated area wa s approximately 10 x 10 mm. There was no significant difference in shrinkag e between the grid (27% +/- 8.7%) and paintbrush (29% +/- 7.9%) patterns. I n the in vivo study, stifles of 24 sheep were randomly assigned to the pain tbrush or the grid pattern groups and treatment was performed arthroscopica lly. Sheep were sacrificed immediately after surgery, or at 2, 6, or 12 wee ks after surgery. At 6 weeks after surgery, confocal microscopy demonstrate d that treated areas had almost completely repaired in the grid group; some nonviable areas were still present in the paintbrush group. Mechanical tes ting at 6 weeks indicated that joint capsule in the grid group had better m echanical properties than capsule in the paintbrush group. This study revea led that radiofrequency treatment of joint capsule in a grid pattern allowe d faster healing than tissue treated in a paintbrush pattern.