Radial head subluxation

Synonyms: nursemaid's elbow, babysitter's elbow, pulled elbow

What is radial head subluxation?

Isolated radial head subluxation without fracture, commonly referred to as “nursemaid’s elbow” or “pulled elbow,” is most often caused by the classical mechanism of axial traction applied to the forearm (pulling), allowing the annular ligament to slip and become entrapped between the radial head and capitellum.¹

The mechanisms of injury include swinging the child by the arms, lifting the child, wrestling, pulling away, tripping, getting dressed, direct trauma or fall.²

Symptoms after only minor or no trauma mean that puzzled, anxious parents may consult a GP rather than attending hospital. It is important to diagnose and treat this condition promptly. It is also important to appreciate the differential diagnosis and to recognise atypical cases because investigation (eg, X-ray) and/or referral are necessary.

How common is radial head subluxation? (Epidemiology)¹

• Isolated radial head subluxation without fracture, commonly referred to as “nursemaid’s elbow” or “pulled elbow,” is the most common upper extremity injury in children younger than six years old, peaking at two to three years.

• Roughly half to two-thirds of the cases are caused by the classical mechanism of axial traction applied to the forearm (pulling), allowing the annular ligament to slip and become entrapped between the radial head and capitellum.

• Radial head subluxations or dislocations rarely present without an associated ulnar fracture or elbow dislocation in adults.

Symptoms of radial head subluxation (presentation)

History

• The age and history usually suggest the diagnosis.

• There is often no history of trauma.

• There is usually a history of elbow pain, sudden crying and characteristic upper limb immobility:
  

  • The arm is moved at the shoulder but not at the elbow.

  • The elbow is held slightly flexed and pronated.

  • The forearm is often held against the abdomen.

  • Pain is centred around the radial head.

• Often, on closer questioning, the arm has been pulled axially. Such axial traction may have occurred:
  

  • Just pulling an arm through a sleeve whilst dressing.

  • Lifting a child by one hand up and over an object.

  • Picking up or trying to prevent a child falling whilst holding hands.

  • Moving in opposite directions quickly whilst holding hands.

Examination

• Examination usually confirms the diagnosis.

• The child is usually apprehensive and protects the affected arm.

• Anxiety predominates over pain.

• The arm is held as above flexed slightly between 15° and 20°.

• The child may support the affected hand against the abdomen or with the unaffected hand.

• There is no systemic illness, warmth or swelling (these suggest other causes).

• The child is reluctant to move not only the elbow but also the wrist and fingers (in case this moves the elbow).

• Tenderness at the radial head is present.

• Flexion, extension, pronation and supination of the forearm are all resisted.

Differential diagnosis

• Congenital dislocation of the radial head.

• Fractures affecting upper limb mobility: (always consider the possibility of non-accidental injury):
  

  • Monteggia fracture.

  • Ulnar greenstick fracture (the ulnar border on a lateral radiograph should be straight without bowing or deformation).

  • Fractured clavicle.

  • Other hand and wrist fractures.

• Other causes of an immobile upper limb, for example:
  

  • Osteoarthritis, rheumatoid arthritis.

  • Septic arthritis.

  • Osteomyelitis.

  • Neurological causes.

Investigations

• Imaging studies (including X-rays) are not usually necessary.

• X-rays are required when:
  

  • A fracture is suspected because of significant tenderness with swelling, bruising or deformity.

  • Reduction is unsuccessful after two or three attempts.

• Ultrasound can be used to evaluate the annular ligamentous injury and show displacement of the radial head from the capitellum.

• MRI studies can be used to confirm subluxation and assess ligamentous damage.

Management of radial head subluxation³

If the diagnosis can be confidently made and there is no suggestion of a fracture after careful history and examination, pulled elbow can be managed in the primary care setting. Indeed, this can prevent delay and reduce the child's pain and anxiety more quickly. Key points are as follows:

• Manipulation should be performed only after careful examination to restore the radial head to its correct position within the annular ligament.

• There is low-quality evidence that the pronation method may be more effective at first attempt than the supination method for manipulating pulled elbow in young children.⁴

• After successful reduction it may take half an hour for normal function to return. In children aged under 2 years, and where there has been a delay of more than four hours before reduction, return to normal function may take longer.

• If manipulation is successful and function is restored no further treatment or investigation is required. If unsuccessful after two or three attempts and a suitable wait for restoration of function then referral for further assessment and X-rays is necessary.

• To prevent recurrence, education of parents, grandparents, siblings, and carers is essential after reduction. Such education is essentially to describe the nature and mechanism of injury, with particular emphasis on scenarios likely to produce recurrence.

Manipulation technique: supination/flexion

Grasp the affected elbow with one hand to immobilise the elbow and palpate (locate) the radial head (usually with the thumb).

With the other hand apply axial compression ('pushing in') whilst supinating the forearm and flexing the elbow.

A click or snap will be felt over the radial head, confirming accurate relocation.

Some suggest slight pressure at the radial head.

Some suggest extension rather than flexion of the elbow, but there is some evidence to suggest this is less effective.

Manipulation technique: hyperpronation

This may be more effective:³

Grasp as above, applying pressure over the radial head with one hand (allow the thumb to palpate the radial head).

Pronate and flex the elbow with the other hand whilst grasping the affected wrist.

Relocation should be felt as above.

Follow-up

Follow-up is not routinely required if reduction is felt and function restored. However, it is essential to provide advice on how to avoid any recurrence.

Complications of radial head subluxation

The radial head may fail to reduce. This is rare.

Prognosis²

Prognosis is excellent. According to one study, 56% of the children were able to use the affected arm immediately or within 5 minutes of reduction, and this number was 74% before 10 minutes. In only 4% of children, the time to re-use the limb was more than 30 minutes.

One of the possible factors affecting the delay in re-using the injured limb is the delay from dislocation to reduction and one study found a delay of more than 4 hours had a direct relationship with the time taken to use the affected arm.

Prevention of radial head subluxation

• Education of the whole family comprises:
  

  • Avoiding lifting children by one arm.

  • Avoiding lifting or swinging by arms.

  • Description of the mechanism of injury.