Proximal physeal fractures, Salter-Harris type II

Fractures of the proximal tibial physis are relatively common in foals. They occur as a result of lateral to medial bending forces (arrow) applied to the stifle region. The resulting fracture originates at the medial aspect of the physis, traverses the physis a variable distance, then breaks into the metaphysis and exits distal to the physis through the lateral metaphyseal cortex. The size of the triangular metaphyseal fragment (Thurston-Holland Sign in the human literature) is variable as is the degree of displacement.

Foals with this fracture also may have a tibial crest fracture concurrently. Therefore the entire area should be evaluated carefully using different radiographic projections.

Craniocaudal radiographic projection of a typical Salter-Harris Type II fracture of the proximal tibia in a 30 day old Warmblood Foal.

Tibial fractures usually develop as a result of trauma, such as kicks or falls. The exception to this are tibial stress fractures, which are an accumulation of cyclic loading and bone fatigue.

The most common types of tibial fractures are:

1. Salter Harris Type II
2. Tibial crest fractures
3. Simple diaphyseal fractures
4. Comminuted diaphyseal fractures
5. Diaphyseal stress fractures
6. Medial malleolus fractures
7. Lateral malleolus fractures
8. Distal physeal fractures

Radiography provides the most meaningful information as to location and configuration of the fracture(s).
In most cases 4 views at 45 degree intervals provide adequate information for an exact diagnosis. For the evaluation of the proximal tibia typically a lateromedial and a caudocranial projection each is enough.
Nuclear scintigraphy is useful in the identification of tibial stress fractures, which may be radiographically inapparent.