Fractures of the Small Metacarpal-Metatarsal Bones (Splint Bones) in Horses

Fractures of the second and fourth metacarpal bones (splint bones) in horses are not uncommon. They can be caused by direct trauma, such as interference by the contralateral leg or a kick; however, these fractures can also accompany suspensory desmitis and the resulting fibrous tissue encapsulation of the distal, free end of the bone.

Typically, splint bone fractures occur approximately 5 cm from the distal end of the bone. Acute inflammation and lameness occur immediately after the fracture but can recede after several days of rest and recur only after work.

Diagnosis of splint bone fractures in horses is based on radiographic examination. Ultrasonographic examination of the suspensory ligament might also be beneficial to determine a more accurate prognosis, as well as to guide a rehabilitation program.

Treatment of splint bone fractures is surgical removal of the bone proximal to the fracture; occasionally, though, conservative management is successful.

Fractures involving the proximal one-third of the bone might require surgical stabilization of the bone to prevent carpal instability, particularly if the fracture involves the second metacarpal bone.

The prognosis for horses with splint bone fractures is based on the severity of any associated suspensory desmitis, which has a greater bearing on future performance than does the splint fracture itself.

Fractures of the second and particularly the fourth metatarsal bones are common and usually arise from direct trauma (eg, a kick from another horse). Simple, comminuted, and displaced fractures occur and are often associated with overlying wounds. Diagnosis is confirmed by radiography.