Northwestern University Feinberg School of Medicine

Orthopedic Teaching

Shoulder Case 3 Diagnosis

Anterior Shoulder Dislocation


Diagnosis

Plain films are appropriate before reduction in the neurovascular intact patient, and should be repeated after reduction.
The scapular Y view is important in addition to standard shoulder views to confirm the type of dislocation. It should be ordered whenever assessing for dislocation. Imaginary lines connecting the scapular spine (acromion), the coracoid process, and the body of the scapula all intersect at the glenoid fossa forming the "Y" of the scapula.
  • In a normal x ray, the humeral head is directly centered on the "Y".
  • The humeral head is anterior to the "Y" in anterior dislocation.
  • The humeral head is posterior to the "Y" in posterior dislocation.

Radiography can also detect lesions caused by dislocation that are associated with an increased risk of recurrent shoulder dislocation:

  • Hill-Sach's deformity -cortical depression in the head of the humerus
  • Bankart lesion - avulsion of the anteroinferior glenoid labrum (where it attaches to the inferior glenohumeral ligament)

These lesions are sometimes only diagnosed on post-reduction films.