Radial head subluxation

Radial head subluxation (commonly referred to as “pulled elbow” or “nursemaid's elbow”) refers to the partial dislocation of the head of the radius at the level of the radio-humeral joint. The injury most commonly occurs in young children after sudden tugging of the outstretched and pronated arm (e.g., adults suddenly pulling a child's arm to keep it from falling). Clinical signs include painful and limited movement of the upper extremity and guarding, with the arm held in a flexed and pronated position. The diagnosis is often made based on typical symptoms and therefore x-ray imaging is generally not required. Management is usually conservative and involves closed, manual reduction of the radial head. The reduction can be carried out in an outpatient setting and does not require any immobilization of the elbow or further surgical treatment.

• Subluxation of the radial head, facilitated by the weakness of the immature annular ligament, causing the radius to slip out of the annular ligament and the annular ligament to become entrapped within the humeroradial joint ^[1][2]

• Age
  • 1–5 years (peak incidence between two and three years) ^[3][4]
  • Radial head subluxation is the most common elbow injury in children under 5 years of age and occurs exclusively in this age group. ^[5]
• Sex: ♀ > ♂ ^[4][6]
• Risk factors
  • Previous history of radial head subluxation ^[3][6]
  • Obesity ^[4]

Epidemiological data refers to the US, unless otherwise specified.

• Traumatic (most common)
  • Sudden axial traction of the pronated and extended forearm ^[7]
  • Typical activities: adult quickly pulls up a falling child by the hand; , swings a child by the hands, or drags a child by the arm (hence the term “nursemaid's elbow”) ^[8][9]
• Congenital structural abnormalities: e.g., collagen abnormalities, abnormal endochondral ossification of the growth plate and ossification sites external to the joint ^[10]

• Child holds the arm, with the elbow extended or slightly flexed and pronated. ^[5]
• Pain, aggravated by movement ^[5]
• Limited extension and flexion
• No swelling
• History and findings may be atypical, especially with children < 3 years of age, who may be unable to properly articulate their symptoms or the circumstances of the injury. ^[1]

The condition is predominantly clinically diagnosed; , with a limited role for imaging. A successfully executed closed manual reduction (indicated by cessation of pain and ability to move the joint freely) is not just therapeutic but also diagnostic (see “Treatment” below).

• X-ray
  • Not necessary, if the patient presents with typical history and clinical signs. ^[2]
  • May be useful in atypical or irreducible cases to identify a displacement of the radiocapitellar line without further disruption of the radiocapitellar joint ^[11]
• Ultrasound: may be considered to prevent misdiagnosis and delayed treatment in children too young to properly articulate their symptoms ^[12]
• MRI: may be considered in atypical cases or where congenital structural anomalies are suspected ^[1]

Radial head fracture

• Etiology
  • Fall on outstretched hand with the elbow partially flexed and pronated ^[13]
  • Stress fracture (e.g., in throwing sports)
• Epidemiology: occurs more commonly in adults than radial head dislocation or subluxation ^[14]
• Clinical presentation ^[13]
  • Radial head region is tender to touch
  • Pronation and supination of the forearm is painful
  • Effusion or hemarthrosis of the elbow joint may be present. ^[14]
• Diagnostic: Elbow x-ray in two planes may show typical fat pad sign (elbow joint). ^[14]
• Treatment
  • Nondisplaced fractures are treated conservatively with a plaster splint for approx. 2 weeks. ^[15]
  • Complex fractures are treated surgically ^[13][14]
• Complication: incorrect reduction can lead to cubitus valgus

The differential diagnoses listed here are not exhaustive.

• Reduction maneuvers
  • While applying pressure to the radial head, the following maneuvers are carried out: ^[16][17]
    • Supination of the forearm with the elbow in slight flexion
    • Hyperpronation of the forearm
  • In successful reduction, a “click” might be heard ^[6]
  • Post-reduction: clinical control of normal range of motion of the elbow ^[6][18]
  • A second attempt at reduction may be necessary (by using the same or a different approach), if normal range of motion is not achieved ^[16]
  • Immobilization of the arm is not required. Most children regain full mobility of the elbow in a short time (10–30 minutes post reduction). ^[6][18]
• Surgery: only indicated when closed manipulative reduction is unsuccessful ^[19]
• Prevention: Parents and caretakers should be educated about the most common mechanisms of injury to prevent recurrence. ^[8]