dislocation of the elbow joint

see also:

• the acutely painful elbow

• the elbow is the second most commonly dislocated large joint after the shoulder joint
• 80% are postero-lateral
• most have osteochondral injury which may only be evident on surgical exploration but fortunately, most do not require intervention
• ~25% of them also have a radiologic evident fracture - radial neck and/or coronoid process
  • fracture of both has a much worse prognosis for long term function - “the terrible triad”
  • NB. in children the medial epicondyle is commonly fractured and may become entrapped in the joint during closed reduction
• concomitant injury to the medial flexor muscles - either in the belly or at the insertion into the medial condyle also generally occurs

• primary stabilizers of the elbow:
  • the intact bones - olecranon and coronoid, head of radius, and lower end of the humerus.
    • the radial head provides 30% of the valgus stability.
• secondary stabilizers of the elbow:
  • the medial and lateral collateral ligaments
    • with an intact MCL complex, removal of head of radius results in no instability, HOWEVER, dislocation usually always disrupts the LCL first then the MCL - usually with complete rupture
• avascular necrosis of radial head
  • the radial head is dependent upon blood supply from the radial neck and this is jeopardised in elbow dislocations with radial neck fractures

• most commonly a relatively “minor” fall from standing onto outstretched hand with elbow hyper-extended
• “terrible triad injury” tends to result from fall onto outstretched hand with elbow semi-flexed and supinated with a valgus posterolateral force applied

• usually easily ascertained clinically due to the loss of triangular orientation of the posterior bony prominences - medial and lateral condyles of humerus and the olecranon tip
  • if this triangle is intact, then consider a supracondylar fracture of the humerus and not a dislocation
• confirmed on Xray which is important to exclude concurrent fractures

• assess for neurovascular injury and other injuries
  • ulnar nerve injury is most common with posterior dislocations
  • anterior branch of the median nerve may become entrapped during closed reduction
  • brachial artery injury may occur with the less common anterior dislocations especially open dislocations
• Xray
• analgesia - NSAIDs
• most cases can be reduced by closed reduction:
  • requires adequate muscular relaxation and appropriate analgesia
  • analgesic adjunct eg. nitrous oxide, opiates
  • traction-counter-traction method for posterior dislocations:
    • with elbow slightly flexed and in supination, and someone fixing the upper humerus, gentle axial traction is applied at the wrist until it reduces (may also need pressure to tip of olecranon) and then the elbow is flexed to 90deg in pronation (pronation locks the unstable lateral side)
  • Mahmoud-Pearse technique
    • anterior pressure to olecranon whilst applying posterior pressure to humerus supracondylar ridges
    • see https://www.oatext.com/A-novel-technique-for-reduction-of-posterior-dislocation-of-the-elbow-joint-.php
• re-assess for neurovascular injury
• post-reduction Xray to confirm reduction and re-assess for fractures
• POP backslab, broad arm sling to avoid extension of the elbow
• simple dislocations without fractures
  • only 1-2% have recurrence of dislocation
  • usual Mx is splint at 90deg for 5-10 days then early supervised mobilisation (supervised via physiotherapist preferably)
  • extension block brace is often used for 3-4 weeks then reduced over the following 3 weeks
  • light duties after 2 weeks from injury
  • NB. immobilisation for > 3 weeks results in POOR ROM outcomes!
• ortho R/V - same day if there are fractures, neurovascular injury, widened joint space on XRay (suggests fragment inside), persistent instability, or unable to reduce
  • patients with avulsion of the radial head due to fracture at the radial neck:
    • this will generally require operative reduction
    • if the radial head is in 2 or less fragments then internal fixation may be needed
    • if the radial head is in 3 or more fragments then it is generally regarded as being irreparable and needs to be excised and an artificial head prosthesis inserted and/or the MCL is repaired
      • excision without MCL repair results in very unstable joint which tends to dislocate even in plaster
      • retaining a fragmented radial head and repairing ligaments offers stability but usually long term pain
      • excision with MCL repair appears to give very good long term results with good stability and range of movement ¹⁾
      • excision of the radial head is not recommended during childhood as it can result in a painful wrist with relative shortening of the radius and ulnar plus deformity
    • cases of “terrible triad” require complex orthopaedic Mx
    • there is risk of avascular necrosis of the radial head
  • patients with coronoid fracture with radial head fracture
    • have LCL injury as well
    • varus posteromedial rotatory instability