The literature on recurring dislocation of the shoulder has been reviewed recently by Henderson1 and by Speed2 and will not be repeated in this paper.
In primary traumatic dislocation, the humeral head is thrust downward and forward, as the arm is hyperabducted. The capsule gives way along the margin of the glenoid rim between the subscapularis in front and the origin of the triceps on the posterior margin. From this position, the direction of force carries it forward beneath the coracoid process in 90 per cent of the cases.
Recurrence of dislocation follows excessive function or accidental hyperabduction of the arm before the torn capsule has had sufficient time to heal. Each succeeding dislocation is accomplished with greater ease, and the capsule finally becomes patulous and accommodates the head outside the glenoid cavity.
In a dissection of the anterior shoulder region three days after a recurring dislocation, I
CARRELL WB. HABITUAL DISLOCATION OF THE SHOULDER. JAMA. 1927;89(12):948-952. doi:10.1001/jama.1927.02690120024008