Medially Based Anterior Capsular Shift of the Glenohumeral Joint

Abstract

The effect of a medially based anterior capsular shift on translational and rotational range of motion and posterior capsular strain was investigated in an in vitro model. Six cadaveric shoulders were tested in a robot-assisted shoulder simulator. Translational and rotational range of motion were reduced by the capsular shift, particularly with the shoulder at higher elevation angles. At 60° of elevation, anterior translation was decreased 1.9 2.9 mm, and posterior translation was decreased 2.3 6.2 mm. External rotation was decreased 11.5° 10.2°, and internal rotation was decreased 8.9° 5.7°. Posterior capsular strain change was dependent on elevation angle. At 30° of elevation, strain tended to increase 5.0% 7.3% in the inferior aspect and 2.9% 2.6% in the superior aspect, with no change detected in the medial aspect. At 60° of elevation, strain increased 6.6% 8.0%, 3.2% 2.6%, and 4.4% 3.5% in the inferior, middle, and superior aspects, respectively. Our results support the use of the medially based anterior shift for shoulders with anterior-inferior instability or multidirectional instability with posterior involvement.