Fractures
Metacarpal/Metatarsal Condyles
Basic Information 
Definition
Fractures of the distal condyles of the third metacarpus/metatarsus (MC/MT-III). Fractures originate at the distal articular surface and propagate proximally in the sagittal plane.
Synonyms
These fractures are simply referred to as condylar fractures or longitudinal fractures of the third metacarpal/metatarsal condyles.
Epidemiology
Genetics and Breed Predisposition
Condylar fractures are most commonly seen in Thoroughbred racehorses. They also occur in Standardbred racehorses; racing Arabians; and occasionally polo ponies, steeplechasers, and eventers.
Clinical Presentation
Disease Forms/Subtypes
• Fractures may involve either the lateral or medial condyle.
Lateral condylar fractures are either incomplete or complete (exit the ipsilateral cortex). The majority of complete fractures are displaced.
Medial condylar fractures rarely exit the ipsilateral cortex and instead have a propensity to propagate proximally into the diaphysis or proximal metaphysis. They do so in either a spiral configuration or in a sagittal plane that changes abruptly in mid-diaphysis to take on a Y-shaped configuration. This type (Y configuration) is at risk of catastrophic failure.History, Chief Complaint
• Most horses present with an acute onset of moderate to severe lameness during or shortly after a race or a workout. In some cases, horses finish the race well with no “bad step” perceived by the rider. With some incomplete fractures, lameness is not noted until the following day.
• Some horses have a history of pain (“soreness”) and inflammation (heat and effusion) in the associated fetlock joint at some point in the days or weeks leading up to fracture.
Physical Exam Findings
• Horses with condylar fractures generally bear full weight on the limb and exhibit mild to severe lameness at the walk. Lameness in many cases improves rapidly so that by 24 to 48 hours, there may be minimal lameness at the walk (most evident on turns).
• Fetlock effusion is invariably present and is typically marked. Horses with complete lateral condylar fractures often have noticeable soft tissue swelling along the lateral aspect of the distal metaphysis. Pain on lower limb (fetlock) flexion is typically moderate to severe in the acute stage.
Etiology and Pathophysiology
• Condylar fractures are fatigue fractures resulting from accumulated high-speed cyclic strains.
• Subchondral microdamage develops where stress is concentrated along the condylar groove (junction between the condyle and sagittal ridge).
• Overt fracture occurs acutely and begins in the distal palmar/plantar aspect of the articular surface and propagates proximally between or along the sagitally oriented “plates” of trabecular bone.
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