Skeletal Trauma > Shoulder > Posterior Dislocation

Posterior Dislocation

Posterior Shoulder Dislocation Unlike anterior dislocation, posterior dislocation of the shoulder is very uncommon. Usually results from direct force to the anterior shoulder or indirect force applied to the arm combining adduction, extension and internal rotation. This diagnosis can often be missed on standard AP view. A standard axillary projection and/or an AP projection in which the patient has been rotated 40° toward the affected side is key!

AP View of Posterior Dislocation

Transscapular Y View of Posterior Dislocation

Axillary View of Posterior Dislocation

Notice that the posterior dislocation is more easily observed on the axillary view. Also notice that in the image above, there is an impaction fracture (arrow) of the humerus from its contact with the glenoid.