Glenohumeral translation after arthroscopic thermal capsuloplasty with a radiofrequency probe

The purpose of this study was to determine whether there are changes in ant erior and posterior glenohumeral translation after arthroscopic thermal cap suloplasty with a radiofrequency probe. Anteriorly directed loads of 15 N a nd 20 N were sequentially applied to the humerus of each of 5 cadaveric gle nohumeral joints, and anterior translation on the glenoid was measured thro ugh use of a customized translation apparatus and an electromagnetic tracki ng device. The tests were then repeated with posteriorly directed forces, a nd posterior translation was measured. During testing, the glenoid was rigi dly fixed and the glenohumeral joint was positioned to simulate 90 degrees of shoulder abduction and 90 degrees of external rotation. By means of the radiofrequency probe, thermal energy was then applied to the anteroinferior capsuloligamentous structures; anterior and posterior translation measurem ents were repeated. The results showed a significant reduction in anterior and posterior translations after thermal capsuloplasty (P < .05). Anterior translation decreased ham 6.8 to 4.0 mm (a 41% decrease) with the 15-N load and from 8.6 to 4.9 mm (a 42% decrease) with the 20-N load. Posterior tran slation decreased from 9.3 to 5.8 mm (a 36% decrease) with the 15-N load an d from 10.4 to 6.5 mm (a 35% decrease) with the 20-N load. The results of t his study indicate that the radiofrequency probe can be used to decrease bo th anterior and posterior glenohumeral translation in vitro. The biological effect on heat-treated tissues over time needs to be studied to prove that this is a satisfactory treatment for glenohumeral instability.