What area of the tarsus is most commonly involved in OCD in the equine patient?

What area of the tarsus is most commonly involved in OCD in the equine patient?

• A. Lateral malleolus
• B. Calcaneal process
• C. Lateral distal tibia
• D. Cranial intermediate ridge of distal tibia

Answer: (D)

In horses, the most common OCD site in the tarsus is the cranial intermediate ridge of the distal tibia. This area is part of the tarsocrural joint’s articular surface and endochondral ossification defects tend to manifest there because it bears substantial weight during movement. Repetitive loading during growth can cause focal cartilage and subchondral bone lesions, leading to osteochondral defects that may loosen or peel. Clinically this location is repeatedly implicated in equine tarsal OCD, often visible on radiographs as irregularity or flake formation of the distal tibial ridge. The other sites listed are less typical for primary OCD in the equine tarsus; they can be involved in some cases, but the cranial intermediate ridge of the distal tibia remains the classic, most frequent location.

In horses, the most common OCD site in the tarsus is the cranial intermediate ridge of the distal tibia. This area is part of the tarsocrural joint’s articular surface and endochondral ossification defects tend to manifest there because it bears substantial weight during movement. Repetitive loading during growth can cause focal cartilage and subchondral bone lesions, leading to osteochondral defects that may loosen or peel. Clinically this location is repeatedly implicated in equine tarsal OCD, often visible on radiographs as irregularity or flake formation of the distal tibial ridge. The other sites listed are less typical for primary OCD in the equine tarsus; they can be involved in some cases, but the cranial intermediate ridge of the distal tibia remains the classic, most frequent location.