13-E/1.1   Simple epiphysiolysis, SH I

The pattern of this injury is characterized by an epiphyseal separation (Salter-Harris I).

It occurs mainly in infants and very young children whose capitellum is still not ossified. Diagnosis can therefore be very difficult.

Note: Be aware of the possibility of nonaccidental injuries in younger children.

Radiologically this lesion is difficult to distinguish from elbow dislocation, especially if the capitellum is not ossified.

Ultrasonography, or arthrography, is helpful in reaching the correct diagnosis.

Young child (2-month-old):

• This x-ray is of a Salter-Harris I fracture of the distal humerus in a 2-month-old baby. It looks like an elbow dislocation but ultrasonography, arthrography, or MRI can clarify the diagnosis
• In this age group, elbow dislocations are very rare and x-rays as illustrated should raise the strong suspicion of a Salter-Harris I injury

Older child (older than 6 years):

• The relationship between the forearm and the ossified capitellum is correct which distinguishes this from an elbow dislocation on plain radiographs
• An elbow dislocation with a lateral condylar fracture is a more common injury (13-E/4.1)
• Arthrography is useful in precise diagnosis