13-E/7L Avulsion of/by the lateral collateral ligament
The pattern of this fracture is an osseo-ligamentous avulsion of the lateral epicondyle. The classification is independent of fragment size and displacement.
This very rare fracture tends to occur in combination with elbow dislocation.
Pearl: If a medial shift is seen, consider the possibility that the elbow luxation is accompanied by a lateral epicondylar avulsion and investigate accordingly.
This fracture is only visible on an x-ray if there is a bony component, mostly seen in older children.
Additional ultrasonography and/or MRI are indicated if there is diagnostic uncertainty.
Relevant clinical features include:
- Fat pad sign
- Local clinical swelling
- Local anterior tenderness
- Painful restriction of motion
Older child (older than 6 years):
- Around puberty the lateral epicondyle starts to ossify. Once this occurs, the ossific center can be seen on a plain x-ray
- On this x-ray a multifragmentary avulsion and displacement of the lateral epicondyle can be seen clearly in the AP view
- As this fragment usually is less severely displaced than the medial epicondyle, the fragment cannot usually be seen on the lateral view
- Additional investigation, such as CT scan or MRI, is indicated if the diagnosis remains unclear after AP and lateral x-rays
