Classification and Physical Findings in Dislocations of the Glenohumeral Joint:

Type Description/Mechanism of Injury Associated Injuries
Anterior Patient presentation:
Arm is held in abduction and slight external rotation with shoulder appearing "squared off."
- Axillary nerve palsy
- Fracture of the greater tuberosity
- Fracture of the humeral neck
- Disruption of the glenoid rim (Bankart lesion)
Mechanism of injury:
Indirect blow with arm in abduction, extension, and external rotation.
  Subcoracoid Humeral head is displaced anterior to the glenoid and inferior to the coracoid. Axillary artery disruption
  Subglenoid Humeral head lies inferior and anterior to the glenoid fossa.  
  Subclavicular Humeral head is displaced medial to the coracoid below the clavicle.  
  Intrathoracic Humeral head lies between the ribs and thoracic cavity.  
Posterior Patient presentation: Fractures of the posterior glenoid rim
  Subacromial Arm is adducted and internally rotated. Fractures of the humeral head (reversed fractures of the Hill-Sachs deformity)
  Subglenoid Anterior shoulder is flat and the posterior aspect full.
  Subspinous Coracoid process is prominent. Fractures of the humeral shaft
  Patient will not allow external rotation or abduction because of severe pain. Fractures of the lesser tuberosity
  Mechanism of injury:  
Indirect force that produces forceful internal rotation and adduction.  
Inferior (luxatio erecta) Patient presentation:
- Patient is in severe pain.
- Humerus is fully abducted.
- The elbow is flexed.
- Patient's hand is on or behind the head.
- Humeral head can be palpated on the lateral chest wall.
- Severe soft tissue injuries
- Fractures of the proximal humerus
- Rotator cuff tear
- Neurovascular compression injuries
Mechanism of injury:
- Neck of the humerus is levered against the acromion and inferior capsule tears.
- Humeral head is forced out inferiorly.