Metacarpals/-tarsals III: Diaphyseal dorsal cortical stress fractures

McIII stress fractures eventually results from an accumulation of cyclic loading and subsequent bone fatigue.

In foals four types of fractures are seen:

1. Salter-Harris Type II physeal fracture
2. Simple mid shaft transverse of oblique fractures
3. Multifragment diaphyseal fractures
4. Fractures of the proximal metaphysis

In adult horses, the most common types of fractures of the 3rd metacarpal/metatarsal bone are:

1. Distal metaphyseal fractures
2. Simple diaphyseal fractures
3. Comminuted diaphyseal fractures
4. Proximal metaphyseal fractures
5. Non-displaced proximal articular fissure fractures
6. Dorsal stress fractures

The actual management of the fractures encountered in foals and adults is, where ever possible, discussed together. If differences arise they will be mentioned or discussed in separate module.

The animal is acutely “fracture-lame” and is unable to place weight on the injured limb. Except in fissure fractures, attempts to apply some weight results in acute angulation of the involved bone associated with crepitation sounds.
Because of the danger of skin penetration by the sharp points of the fragments ambulation is strongly discouraged.

Because the McIII/MtIII region is only covered by skin subcutaneous tissue and tendons, appropriate first aid is of utmost importance to prevent inadvertent penetration of the skin by the sharp fracture edges.
A full-limb splint bandage consisting of thin layer of cotton tightened initially by an elastic adhesive bandage and a second layer incorporating a palmar/plantar splint into an additional bandage layer, should be applied as soon as the fracture is detected.

It is strongly discouraged to have the patient walk long distances with the splint in place to reach a trailer. Therefore the trailer should be driven as close to the patient as possible, followed by the immediate transport to a clinic experienced in fracture management.

Radiographs are best taken through the splint bandage or cast to avoid additional damage the fracture ends and the surrounding tissues, as well as to reduce costs to the owner. The radiographs taken with the splint bandage in place are usually of adequate quality to allow to make a correct diagnosis and subsequently to decide whether it is worth while to treat the fracture or to euthanatize the patient right away. If needed, better quality radiographs are taken immediately prior to surgery while under anesthesia on the surgery table.

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.

If available, other diagnostic imaging techniques, such as ultrasonography or computed tomography may provide valuabe additional information on the fracture configuration.