Elbow Dislocation - Pediatric

Introduction
  • Description
    • pediatric elbow dislocations usually occur in older children (10-15 years) and can be associated with other elbow fractures including a medial epicondyle fracture with an incarcerated intra-articular bone fragment.
      • treatment is usually closed reduction followed by brief immobilization unless the medial epicondyle has an incarcerated fragment in the joint that is blocking reduction.
  • Epidemiology  
    • incidence
      • 3-6% of all pediatric elbow injuries
    • demographics
      • male:female = 3:1
      • most common in 10-15 year olds
      • very rare in younger children < 3 years old
  • Pathophysiology
    • mechanism of injury
      • fall onto an outstretched hand
    • pathoanatomy
      • posterior dislocation
        • hyperextension, valgus stress, and supination
      • anterior dislocation
        • a direct posterior to anterior force on a flexed elbow
      • relatively small coronoid process in children cannot resist distal and posterior displacement of ulna
  • Associated conditions
    • traumatic
      • avulsion of the medial epicondyle   
        • medial epicondyle fractures are the most common associated fracture 
        • incarcerated intra-articular bone fragment may block reduction
      • fractures of proximal radius, olecranon and coronoid process
      • neurovascular injury
        • brachial artery and median nerve
          • may be stretched over displaced proximal fragment
        • ulnar nerve
          • at risk with associated medial epicondyle avulsions
          • most common neuropraxia
    • congenital
      • dislocation of radial head 
Classification
  • Anatomic classification
    • based on the position of the proximal radio-ulnar joint in relation to the distal humerus
    • includes
      • posterolateral (most common) 
      • posteromedial
      • anterior (rare)
      • divergent 
Presentation
  • Symptoms
    • painful and swollen elbow
    • attempts at motion are painful and restricted
  • Physical exam 
    • inspection
      • elbow held in flexion 
      • forearm appears to be shortened from the anterior and posterior view
    • palpation
      • distal humerus creates a fullness within the antecubital fossa 
    • essential to perform neurovascular examination 
      • assess for brachial artery and median/ulnar nerve injury
Imaging
  • Radiographs
    • required views
      • AP and lateral radiograph of elbow
      • comparison radiographs of the contralateral elbow may be helpful
    • findings
      • loss or radiocapitellar and ulnohumeral relationship but maintained radial and ulnar relationship
      • look for fractures of medial epidcondyle, coronoid, proximal radius
      • "elbow dislocation" in very young (<3 years old) most likely represents a distal humerus physeal separation and raises concern for nonaccidental trauma
Treatment
  • Nonoperative
    • closed reduction, brief immobilization with early range of motion  
      • indications
        • dislocation that remains stable following reduction
          • indicated in the majority of cases
      • reduction technique (see below)
        • should be addressed promptly as reduction should not be delayed 
      • brief immobilization
        • immobilization should be minimized to 1- 2 weeks to minimize risk of stiffness 
      • early therapy
        • encourage early active range of motion
  • Operative
    • open reduction 
      • indications
        • open dislocation
        • incarcerated medial epicondyle or coronoid process in the joint
        • failure to obtain or maintain an adequate closed reduction
        • significant joint instability (rare)
Technique
  • Closed reduction technique 
    • posterior dislocations
      • supine  
        • closed reduction performed with the elbow flexed in forearm supination using gradual traction 
      • prone 
        • forearm hanging from table and anterior directed force on olecranon 
    • anterior dislocations
      • inline traction to distal forearm with a posteriorly directed force on the forearm and an anteriorly directed force on the distal humerus
    • post-reduction films should be reviewed to rule out presence of entrapped bone fragment 
      • must locate medial epicondyle on post-reduction radiographs to ensure it is not within the joint
  • Open reduction
    • approach
      • depends on reason for blocked reduction
        • elbow medial approach   
          • indicated if medial epicondyle avulsion with incarcerated fragment is blocking reduction
Complications
  • Stiffness
    • most commonly loss of terminal extension
      • due to prolonged immobilization
  • Heterotopic ossification
    • vigorous reduction increases risk
  • Neurologic injuries
    • usually transient
    • median nerve injury may occur due to nerve entrapment
    • ulnar nerve most commonly affected if associated medial epicondyle fracture occurs
  • Vascular injury
    • brachial artery may be injured (rare)
  • Compartment syndrome
    • excessive swelling and immobilization in hyperflexion 
  • Chronic instability (recurrent dislocations)
    • associated with coronoid and radial head fractures