Type 4 olecranon fractures are comminuted fractures of the olecranon. Their configuration varies widely, from 3-part fractures to explosion-type injuries comprised by several fragments. In most cases they enter the synovial cavity as well as the articular surface. Those fractures tend to be more common in adult horses, but may occur in foals, too.
The majority of patients with comminuted olecranon fractures will have a characteristic dropped elbow and stand with the carpus flexed. They will be unable to support weight on the affected limb. There will be varying degrees of soft-tissue swelling in the region of the elbow. These fractures can be closed or open.