Shoulder Dislocation

• Shoulder dislocation is where the ball of the shoulder (head of the humerus) comes entirely out of the socket (glenoid cavity of the scapula)
• Subluxation refers to a partial dislocation of the shoulder where the ball does not come fully out of the socket and naturally pops back into place shortly afterwards
• More than 90% of shoulder dislocations are anterior dislocations where the head of the humerus moves anteriorly (forward) in relation to the glenoid cavity
• Anterior dislocations can occur when the arm is forced backwards (posteriorly) while abducted and extended at the shoulder, like someone reaching up and out to catch a heavy rock travelling towards them
• Posterior dislocations are associated with electric shocks and seizures
• Exam questions might challenge you to distinguish between anterior and posterior dislocations, with the answer almost certainly being an anterior dislocation unless the patient has had a seizure or an electric shock
• The glenoid labrum surrounds the glenoid cavity and is a rim of cartilage that creates a deeper socket for the head of the humerus to fit into. When the shoulder dislocates, the labrum can tear along one edge
• Bankart lesions are tears to the anterior portion of the labrum and occur with repeated anterior subluxations or dislocations of the shoulder
• Hill-Sachs lesions are compression fractures of the post
• Bankart lesions


  Tears to the anterior portion of the labrum, occurring with repeated anterior subluxations or dislocations of the shoulder
• Hill-Sachs lesions


  Compression fractures of the posterolateral part of the head of the humerus, caused by the humeral head impacting with the anterior rim of the glenoid cavity during shoulder dislocations
• Axillary nerve damage

  Damage to the axillary nerve from the C5 and C6 nerve roots, leading to loss of sensation in the “regimental badge” area over the lateral deltoid and motor weakness in the deltoid and teres minor muscles
• Fractures that can occur alongside shoulder dislocations

  • Humeral head
  • Greater tuberosity of the humerus
  • Acromion of the scapula
  • Clavicle
• Rotator cuff tears may occur with shoulder dislocations


  Particularly in older patients
• TOM TIP: 'Axillary nerve damage is a common association with anterior dislocations to remember for your exams. This knowledge may be tested in MCQs, where you are asked to identify the nerve, location of sensory loss or muscle affected by weakness'
• Presentation of patients with a shoulder dislocation

  Patients present after the acute injury, aware that the shoulder is dislocated. Muscles go into spasm and tighten around the joint. They hold their arm against the side of their body. The deltoid appears flattened, and the head of the humerus causes a bulge and is palpable at the front of the shoulder
• Assessments for patients with a shoulder dislocation

  • Fractures
  • Vascular damage
  • Nerve damage
• Apprehension Test


  A special test to assess for shoulder instability, specifically in the anterior direction. Likely to be positive after previous anterior dislocation or subluxation of the shoulder. Patients become anxious and apprehensive as the arm approaches 90 degrees of external rotation, worried that the shoulder will dislocate. No pain is associated with the movement, only apprehension
• Investigations

  1. rays may be used in an acute presentation to confirm a dislocation and exclude fractures. They are not always required before reduction. X-rays are performed after reduction to confirm the shoulder is reduced and assess for fractures. Magnetic resonance arthrography is an MRI scan of the shoulder with contrast injected into the joint, used to assess damage and plan for surgery
• Magnetic resonance arthrography

  MRI scan of the shoulder with a contrast injected into the shoulder joint
• Arthroscopy


  Inserting a camera into the shoulder joint to visualise the structures
• Acute Management of a shoulder dislocation

  1. Shoulder should be relocated as soon as safely possible

  2. Muscle spasm occurs over time, making it harder to relocate the shoulder and increasing the risk of neurovascular injury during relocation

  3. Analgesia, muscle relaxants, and sedation as appropriate

  4. Gas and air (e.g., Entonox) may be used

  5. Application of a broad arm sling for support

  6. Closed reduction of the shoulder (after excluding fractures)

  7. Dislocations associated with a fracture may require surgery

  8. Post-reduction x-rays

  9. Immobilisation for a period after relocation of the shoulder
• Ongoing Management of shoulder dislocation

  1. High risk of recurrent dislocations, particularly in younger patients

  2. Physiotherapy recommended to improve shoulder function and reduce the risk of further dislocations

  3. Shoulder stabilisation surgery may be required to improve stability and prevent further dislocations

  4. Underlying structural problems correction such as repairing Bankart lesions, tightening the shoulder capsule, bone graft using bone from the coracoid process, correcting Hill-Sachs lesions
• Shoulder stabilisation surgery

  May be required to improve stability and prevent further dislocations, may be arthroscopic or open procedure, corrects underlying structural problems
• There is a prolonged period of recovery and rehabilitation after shoulder stabilisation surgery (3 months or more)
• Recurrent instability and dislocations can occur in up to 20% of patients after surgery
• Last updated

  August 2021