Should acute anterior dislocations of the shoulder be immobilized in external rotation? A cadaveric study

The high recurrence rate associated with anterior shoulder dislocations may reflect inadequate healing of a Bankart lesion when the arm is immobilized in internal rotation. The effect of external rotation (ER) of the humerus on the glenoid-labrum contact of Bankart lesions was examined in 10 human cadaveric shoulders. The contact force between the glenoid labrum and the glenoid was measured in 60° of internal rotation, neutral rotation, and 45° of ER in 10 human cadaveric shoulders. No detectable contact force was found with the arm in internal rotation. The contact force increased as the arm passed through neutral rotation and reached a maximum at 45° of ER. The contact force returned to 0 g when the arm was returned to neutral rotation. The mean contact force at 45° of ER was 83.5 g. External rotation significantly increases the labrum-glenoid contact force and may influence the healing of a Bankart lesion.