Radial head subluxation

Radial head subluxation (commonly referred to as pulled elbow or nursemaid 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., if an adult suddenly pulls a child's arm to prevent them 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. Diagnosis is usually clinical, based on classic history and examination findings. Imaging is reserved for cases of diagnostic uncertainty or if treatment is unsuccessful. 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. Radial head fractures can cause hemarthrosis, which may be the only visible sign on the elbow x-ray. Most radial head fractures are treated conservatively, with only complex fractures managed surgically.

• 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][5]
• Risk factors
  • Previous history of radial head subluxation ^[6][7]
  • Obesity ^[4]

Epidemiological data refers to the US, unless otherwise specified.

• Traumatic (most common)
  • Sudden axial traction of the pronated and extended forearm ^[5]
  • 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”) ^[3][8]
• Congenital structural abnormalities: e.g., collagen abnormalities, abnormal endochondral ossification of the growth plate and ossification sites external to the joint ^[9]

• Child holds the arm, with the elbow extended or slightly flexed and pronated. ^[5]
• Pain, aggravated by movement ^[5]
• Reduced range of movement (ROM) with 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]

Approach ^[3][5]

• Assess the child's entire arm and clavicle.
• Classic clinical features of radial head subluxation: Proceed directly to treatment.
  • Perform a closed manual reduction.
  • Successful reduction leads to rapid (10–30 minutes) restoration of pain-free normal ROM.
  • Can be repeated once if the initial attempt is unsuccessful
• Diagnostic uncertainty or unsuccessful reduction
  • Obtain imaging to rule out differential diagnoses of radial head subluxation.
  • Unsuccessful reduction but imaging supports the diagnosis:
    • Immobilize the arm.
    • Refer to orthopedic surgery for evaluation within 2 days.

Radial head subluxation is typically a clinical diagnosis; a classic history and examination and successful closed manual reduction confirm the diagnosis. Imaging is not usually required. ^[3]

Closed manual reduction ^[3][10]

• Neither anesthesia nor sedation is required.
• Apply pressure to the radial head and perform one of the following maneuvers: ^[11]
  • Hyperpronation maneuver: Hyperpronate the forearm (with the elbow extended or flexed at 90 degrees). ^[12]
  • Supination-flexion maneuver: Supinate the forearm, then immediately flex the elbow.
• A pop or click may be felt or heard.
• Leave the room, ensuring there are toys for the child to play with, and reassess after 10–30 minutes. ^[5]
• Following successful reduction, the child should have full, pain-free ROM.

Postreduction care

• Neither follow-up nor modifications to normal activity are required.
• Educate caregivers on how to prevent a recurrence. ^[3][5]
• Patients with recurrent subluxations: Consider arm immobilization. ^[3]

Imaging ^[3][5]

Imaging is not routinely performed before or after reduction in patients with classic clinical features of radial head subluxation. Imaging (typically x-ray) is usually only performed in cases of diagnostic uncertainty or unsuccessful reduction.

X-ray elbow (AP and lateral) ^[3][5]

• Indications
  • Mechanism of injury is atypical, significant (e.g., a fall), or unknown. ^[13]
  • Examination is atypical or reveals significant tenderness to palpation, effusion, or ecchymosis.
  • Reduction is unsuccessful.
  • Consider for nonambulatory infants to exclude differential diagnoses of radial head subluxation. ^[13]
• Findings
  • Often normal
  • May show displacement of the radiocapitellar line (not sensitive or specific) ^[14]

Other modalities

• Ultrasound: Findings may include the following.
  • Widened space between the radial head and capitellum
  • Displacement of the annular ligament
  • Hook sign ^[3][15]
• MRI: may be used in atypical cases ^[1]

Radial head subluxation is not typically associated with swelling, deformity, or vascular or neurological compromise; if present, obtain imaging to exclude differential diagnoses of radial head subluxation. ^[3]

• Elbow fractures
  • Supracondylar fracture
  • Olecranon fracture
  • Radial head fracture
• Elbow dislocation
• Soft tissue injury
• Very young children may be unable to articulate the site of pain; the injury could be anywhere from the clavicle to the hand.

Radial head fracture

• Etiology
  • Fall on outstretched hand with the elbow partially flexed and pronated ^[16]
  • Stress fracture (e.g., in throwing sports)
• Epidemiology: more common in adults than radial head dislocation or subluxation ^[5]
• Clinical evaluation ^[16]
  • Perform a neurovascular exam. ^[17]
  • Radial head region is tender to touch.
  • Pronation and supination of the forearm are painful.
  • Effusion or hemarthrosis of the elbow joint may be present.
• Diagnostics: x-ray elbow (AP, lateral and oblique) ^[16][17][18]
  • Fracture through the radial head is not always visible.
  • Evidence of effusion (sail sign and/or posterior fat pad sign) may be the only finding.
  • Comminuted fractures: Consider imaging the wrist, as these fractures may be associated with additional injuries. ^[17]
• Management
  • Assess for indications to consult orthopedics for fractures. ^[18]
  • Provide acute pain management. ^[18][19]
    • Minimize the need for opioids via early immobilization (e.g., sling).
    • Prescribe scheduled acetaminophen; add NSAIDs as needed. ^[20]
  • Nondisplaced fractures are treated conservatively.
    • Immobilize in a sling or posterior long arm splint for 24–72 hours. ^[18][21]
    • Start early ROM exercises. ^[16][22]
  • Complex fractures are typically treated surgically. ^[16]
• Disposition: typically outpatient management with prompt orthopedic follow-up ^[18]
• Complication: cubitus valgus

Treat a positive fat pad sign with corresponding bony tenderness as an occult fracture. ^[18]

The differential diagnoses listed here are not exhaustive.