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Introduction 
  • Epidemiology
    • incidence
      • elbow dislocations are the most common major joint dislocation second to the shoulder
        • most common dislocated joint in children
      • account for 10-25% of injuries to the elbow
      • posterolateral is the most common type of dislocation (80%)
    • demographics
      • predominantly affects patients between age 10-20 years old
  • Pathophysiology
    • mechanism for posterolateral dislocation
      • usually a combination of
        • axial loading
        • supination/external rotation of the forearm
        • valgus posterolateral force 
      • a varus posteromedial mechanism (combined with axial load and forearm external rotation) has also been reported
      • posterior dislocations may involve more than one injury mechanism
    • pathoanatomy
      • associated with complete or near complete circular disruption of capsuloligamentous stabilizers
      • pathoanatomic cascade
        • progression of injury is from lateral to medial
          • LCL fails first (primary lesion)
            • by avulsion of the lateral epicondylar origin
            • midsubstance LCL tears are less common but do occur 
          • MCL fails last depending on degree of energy
Anatomy 
  • Static and dynamic stabilizers confer stability to the elbow
    • static stabilizers (primary)
      • ulnohumeral joint
      • anterior bundle of the MCL
      • LCL complex (includes the LUCL)
    • static stabilizers (secondary)
      • radiocapitellar joint
      • joint capsule
      • origins of the common flexor and extensor tendons
    • dynamic stabilizers
      • muscles that cross the elbow joint, which apply compressive (stabilizing) force
        • anconeus
        • brachialis
        • triceps
  • See complete Anatomy and Biomechanics of Elbow 
Classification
  • Anatomic description 
    • based on anatomic location of olecranon relative to humerus
      • posterolateral
        • most common
  • Simple vs. complex
    • simple  
      • elbow dislocation with no associated fracture 
      • accounts for 50-60% of elbow dislocations
    • complex  
      • elbow dislocation with associated fracture
      • may take form of
        • terrible triad injury  
          • elbow dislocation associated with a LUCL tear, radial head fracture, and coronoid tip fracture 
            • radial head fractures occur in up to 10% of elbow dislocations
        • varus posteromedial rotatory instability
          • elbow injury associated with an LCL tear and a coronoid fracture
          • coronoid fracture characterisitics
            • medial facet fracture
            • comminuted
Presentation
  • Symptoms
    • pain and swelling
  • Physical exam 
    • important to assess
      • the status of the skin - evaluate for open injuries
      • presence of compartment syndrome
      • neurovascular status
      • status of wrist and shoulder
        • concomitant injuries occur in 10-15% of elbow dislocations
Imaging
  • Radiographs
    • recommended views
      • AP and lateral views 
        • assess joint congruency, especially after attempted reduction
      • oblique views
        • assess for associated periarticular fractures
  • CT scan
    • indications
      • suspicion of complex injury pattern
      • useful to identify associated periarticular fractures
Treatment 
  • Nonoperative
    • closed reduction and splinting at least 90° for 5-10 days, early therapy 
      • indications
        • acute simple stable dislocations
        • recurrent instability after simple dislocations is rare (<1-2% of dislocations)
  • Operative
    • ORIF (coronoid, radial head, olecranon), LCL repair, +/- MCL repair
      • indications
        • acute complex elbow dislocations
        • persistent instability after reduction 
          • elbow requires >50-60° to maintain reduction
        • reduction cannot be performed closed
          • often due to entrapped soft tissue or osteochondral fragments
    • open reduction, capsular release, and dynamic hinged elbow fixator
      • indications
        • chronic dislocations
      • postoperative
        • hinged external fixator indicated in chronic dislocation to protect the reconstruction and allow early range of motion
Nonoperative Technique
  • Closed reduction with splinting
    • ensure patient has sufficient analgesia to allow for adequate muscle relaxation
    • reduction maneuver requires a combination of:
      • inline traction to improve coronal displacement
      • forearm supination to shift the coronoid under the trochlea
      • elbow flexion while placing direct pressure on tip of olecranon
    • a palpable "clunk" can be appreciated after most reductions
    • assess post reduction stability 
      • elbow is often unstable in extension 
      • elbow is often unstable to valgus stress
        • test by stressing elbow with forearm in pronatino to lock the lateral side
    • place post-reduction posterior mold splint in flexion and appropriate forearm rotation
      • splint in at least 90° of elbow flexion
      • if LCL is disrupted - elbow will be more stable in pronation
      • if MCL is disrupted - elbow will be more stable in supination
    • obtain post-reduction radiographs
      • if joint is concentric, immobilize (5-10 days) and start early therapy
      • obtain repeat radiographs at 3-5 days and 10-14 days to confirm reduction
  • Rehabilitation
    • initial
      • immobilize for 5-10 days
      • immobilization for >3 weeks results in poor final ROM outcomes
    • early
      • supervised (therapist) active and active assist range-of-motion exercises within stable arc
      • extension block brace is used for 3-4 weeks
      • proceed with light duty use 2 weeks from injury 
    • late rehabilitation
      • extension block is decreased such that by 6-8 weeks after the injury full stable extension is achieved
Operative Technique
  • ORIF of coronoid, radial head, repair of LCL +/- MCL
    • approach depends on the pathology
      • Kocher approach (ECU/anconeus)
        • used to address the LCL complex, common extensor tendon origin, coronoid, capitellum, and/or radial head fractures
        • when approaching joint (ie, for radial head fractures) during deep dissection, make incision slightly anterior to midline of the radial head to protect the posterior fibers of the LCL complex
        • take care with retractor placement to avoid injury to the PIN
      • medial approach
        • used to address the MCL, flexor/pronator mass origin, and/or comminuted coronoid fractures
        • identify and protect the ulnar nerve
      • posterior approach
    • reconstruction
      • coronoid fractures
        • ORIF
          • rarely needed, as most fractures involve only the coronoid tip (proximal to insertion of brachialis)
          • typically approached laterally, but can also be addressed via a medial approach, especially if comminuted
      • radial head fractures
        • ORIF
          • when placing fixation on the proximal radius, one must be aware of the "safe zone" (a 90° arc in the radial head that does not articulate with the proximal ulna) 
            • the "safe zone" can be identified by its relationship to Lister's tubercle and the radial styloid
        • radial head arthroplasty
          • indicated if radial head can not be reconstructed
          • if radial head is replaced the replacement should be anatomic and restore normal length/size
            • this improves the varus and external rotatory stability of the elbow, but stability isn't restored until LCL is addressed
            • excision of the radial head leads to varus/external rotatory instability when the LCL function is absent
      • LCL
        • repaired or reconstructed
        • extensor origin avulsion is common and may be repaired
      • MCL
        • if instability persists following LCL repair, the MCL is repaired or reconstructed
    • hinged external fixator
      • only necessary if elbow remains unstable after attempt at fixation as described above
    • postoperative care
      • depending on stability of the elbow, active ROM exercises may commence while using a brace
      • an extension block may or may not be used
Complications
  • Early stiffness
    • loss of terminal extension is the most common complication after closed treatment of a simple elbow dislocation 
    • early, active ROM can help prevent this from occurring 
    • static, progressive splinting can be helpful after inflammation has decreased
      • often between 6-8 weeks after surgery
    Varus Posteromedial instability
    • injury to the LCL and fracture of the anteromedial facet of the coronoid 
    • solid fixation of the anteromedial facet is critical for functional outcome and prevention of arthrosis
  • Neurovascular injuries
    • brachial artery injuries (rare) typically associated with open dislocations
    • ulnar nerve injury typically results from stretch
    • median nerve injury (rate) typcially associated with brachial artery injury
  • Compartment syndrome
  • Damage to articular surface
  • Recurrent instability
  • Heterotopic ossification
    • may require excision to improve elbow range of motion 
  • Contracture/stiffness
    • correlated with immobilization beyond 3 weeks
 

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