Pediatric elbow radiograph (an approach)

Pediatric elbow radiographs are commonly encountered in the emergency department and, when approached in a systematic fashion, are not as difficult to interpret as most people think!

Systematic review

Ossification

Check that the ossification centers are present and in the correct position. They appear in a predictable order and can be remembered by the mnemonic CRITOE (age of appearance are approximate):

• capitellum (age 1)
• radial head (age 3)
• internal epicondyle (age 5)
• trochlea (age 7)
• olecranon (age 9)
• external epicondyle (age 11)

Alignment

Check the anterior humeral line:

• drawn down the anterior surface of the humerus
• should intersect the middle 1/3 of the capitellum
• if it does not, think supracondylar fracture

Check the radiocapitellar line:

• drawn along the radial neck
• should always intersect the capitellum
• if it does not, think radial head dislocation 
  • check for an accompanying fracture, e.g. Monteggia fracture-dislocation

Effusion

Check for raised fat pads:

• visible posterior fat pad always indicates an elbow effusion
• visible anterior fat pad may be seen in normal patients and should only be thought of as an indicator of an elbow effusion when massively raised
• if there is an effusion in a pediatric patient, think supracondylar fracture or intra-articular fracture, e.g. lateral condyle fracture

Bone cortex

Check around every bone on the film:

• helps to find subtle injuries, e.g. minimally displaced supracondylar fracture or olecranon fracture

Common pathology

Supracondylar fracture

• over 60% of all pediatric elbow injuries
• peak age: 5-7 years
• mechanism: fall onto a hyperextended elbow
• extra-articular fracture
• there may be posterior displacement of the distal segment
• more: supracondylar fracture

Lateral condyle fracture

• 10-20% of all pediatric elbow injuries
• peak age: 6-10 years
• mechanism: usually varus force applied to an extended elbow
• unstable intra-articular fracture
• prone to displacement due to the pull of forearm extensors
• more: lateral condyle fracture

Medial epicondyle avulsion

• 10% of all pediatric elbow injuries
• usually older children and adolescents
• mechanism: FOOSH with full elbow flexion, or posterior elbow dislocation
• most common avulsion injury
• more: medial epicondyle fracture

Radial head dislocation

• 5% of all pediatric elbow injuries
• typically seen in infancy and childhood
• mechanism: isolated traumatic injury
• the radial head is dislocated anteriorly
• check for associated ulnar fracture (Monteggia fracture-dislocation)
• more: radial head dislocation

Radial neck fracture

• 5% of all pediatric elbow fractures
• peak age: 8-11 years
• mechanism: FOOSH with extended elbow and supinated forearm
• most fractures involve the physis
• more: radial neck fracture

Don't miss...

Olecranon fracture

• <5% of all pediatric elbow injuries
• less common in children than adults
• mechanism: either a direct blow, fall on an outstretched hand with flexed elbow, avulsion fracture or stress fracture
• frequently associated with radial neck fracture and elbow dislocation
• more: olecranon fracture