Effect of glenohumeral position on contact pressure between the capsulolabral complex and glenoid in free ALPSA and Bankart lesions

Abstract

Anterior shoulder dislocation is a common injury, but the optimal management of dislocation remains controversial. We hypothesized that reducing the shoulder in externally rotated position would aid the reduction in capsulolabral lesions. Thus, in this study, contact pressure between the capsulolabral lesion and the glenoid in free ALPSA and Bankart lesions was measured using a cadaver model. In 10 specimens, the humerus was externally rotated by abduction on the coronal plane to measure the contact pressure between the capsulolabral complex and glenoid in free ALPSA and Bankart lesions using a Tekscan pressure system. Stability of the joint was confirmed using the Vicon motion analysis system. In the normal shoulder joint, the peak pressure between the subscapularis muscle and the anterior capsule according to the location of the glenohumeral joint decreased to 83.4 +/- A 21.2 kPa in the 0A degrees abduction and -30A degrees external rotation positions and showed a 300.7 +/- A 42.9 kPa peak value in the 60A degrees abduction and 60A degrees external rotation positions. In both free ALPSA and Bankart lesions, the lowest pressure between the labral lesion and the glenoid was measured at 0A degrees abduction and -30A degrees external rotation, and the highest pressure was recorded at 60A degrees external rotation and 60A degrees abduction. The contact pressure between the capsulolabral complex and the glenoid significantly increased when the abduction and external rotation angles were increased. Based on our results, the conservative management in free ALPSA lesions would respond better than Bankart lesions. YWMR-12-0-038.