Dorsomedial articular fracture of the proximal aspect of the third metacarpal bone in standardbred racehorses: seven cases (1978-1990).

The research is about seven Standardbred racehorses suffering from dorsomedial articular fractures in the third metacarpal bone. These fractures caused severe, unilateral lameness that was relieved with midcarpal joint anesthesia in some cases. Radiography revealed non-displaced oblique fractures extending towards the dorsomedial cortex. For one horse, internal fixation followed by a rest period was successful, while others recovered without surgery but required three months of rest.

Introduction of the Study

• The study focused on seven Standardbred racehorses, primarily pacers, with ages ranging roughly from 2 to 4 years.
• These horses exhibited an acute, unilateral, severe lameness after their exercises, which was attributed to dorsomedial articular fractures to the proximal aspect of the third metacarpal bone, a part of their front limbs.

Observations and Diagnostics

• Lameness in all horses was rather severe and generally appeared after racing or training.
• In four out of the seven horses, lameness was treated with midcarpal joint anesthesia. This treatment proves that the cause of the lameness was indeed the fracture.
• A physical examination showed that six horses had a palpable bony swelling, which caused signs of discomfort or pain.
• Radiographic information revealed a non-displaced, articular, oblique fracture extending toward the dorsomedial cortex for an average distance of 28 mm. The range of fracture-extensions observed, however, varied between 15 to 40 mm.
• Chronic periosteal proliferative changes were observed near the distal aspect of the fracture, which matched palpable bony exostoses (bone spurs).
• These bone changes were associated with the medial attachment of the extensor carpi radialis tendon, a muscle responsible for the extension of the wrist.

Treatment Outcomes

• One horse underwent an internal fixation procedure, a type of orthopedic surgery used to stabilize and join the ends of fractured bones. Following the operation, the horse was rested for six months, which resulted in a successful recovery.
• The rest of the horses were given three months of rest without any surgical intervention. Post-rest, these horses showed no signs of lameness.
• Among the non-surgically treated horses, five returned to racing successfully, even setting new personal lifetime records. One horse, although physically sound and successfully re-engaged in training, unfortunately died of colic. The remaining one was not lame during early training.