- A dislocation occurs when a large force slips the humeral head outside of the glenoid fossa or the shoulder joint. This occurs in three different directions. Usually there is damage to the rotator cuff as well as the glenoid labrum (1, 4)
- Anterior dislocation (1, 2, 3, 4)
- also known as a Hill-Sach’s lesion.
- This can be accompanied by a tear of the anterior-inferior labrum which is known as a bankart lesion.
- Damage to the supraspinatus usually results
- The method of injury is generally when the shoulder is in abduction and external rotation and excessive force is placed on the arm causing the humeral head to slip anteriorly out of the joint socket.
- Can result in damage to the Axillary or the Musculocutaneous nerves
- Most common dislocation
- Posterior dislocation (1, 4)
- also known as a reverse Hill-Sach’s lesion
- is often accompanied by a posterior labral tear.
- There can also be damage to the infraspinatus muscle
- Method of injury occurs when the shoulder is in flexion and adduction and forced posterior out of the joint capsule
- Much less common of an injury
- Inferior dislocation (1, 4)
- Least common dislocation
- Occurs when fully abducted arm is forced into further abduction and humeral head slips inferiorly out of the joint OR lifting too heavy of an object at your side can cause an inferior dislocation
- Can result in damage to the Axillary nerve and usually the Suprascapular nerve