Radius et Ulna
The radius and ulna form the forearm (antebrachium), the segment between the elbow and the carpus. In the horse these two bones are fused, restricting movement to the sagittal plane with virtually no pronation or supination. The radius is the primary weight-bearing bone and carries the load from the elbow down to the carpus. The ulna contributes the olecranon tuberosity (point of the elbow), which provides leverage for the triceps muscle to extend the elbow, and then tapers distally, fusing with the radius at about mid-antebrachium. A small interosseous space remains in the proximal third and allows passage of blood vessels. The distal radius features medial and lateral styloid processes that articulate with the carpal bones.
Fractures of the radius are serious injuries that often require surgical repair and carry a guarded prognosis depending on configuration and soft-tissue damage. The olecranon can also fracture, affecting triceps function and elbow extension. Because the bones are fused, the forearm has no rotational capacity, which influences both normal biomechanics and injury patterns.
## Overview Stress fractures of the dorsal cortex of the third metacarpal bone are common in young racehorses. They result from repetitive high-strain loading before the bone has fully adapted. Clini
## Overview Incomplete or stress fractures of the radius occur in racehorses from repetitive loading. They cause forelimb lameness and carry a significant risk of propagating to a complete, catastrop
## Overview Physitis is inflammation of the growth plates (physes) in young horses, often related to rapid growth, nutritional imbalance, or excessive exercise. It causes warm, painful enlargement ar
## Overview Olecranon fracture is a break of the point of the elbow, usually from direct trauma such as a kick or fall. Because the triceps inserts on the olecranon, the horse cannot extend the elbow
Severe lameness with swelling of the forearm or inability to bear weight after trauma needs immediate veterinary attention. Do not attempt to walk the horse long distances until evaluated.
## Overview Stress fractures of the dorsal cortex of the third metacarpal bone are common in young racehorses. They result from repetitive high-strain loading before the bone has fully adapted. Clinical signs are soreness over the cannon after fast work. Incomplete fractures can progress to complete fracture if training continues. ## Causes Cyclical fatigue of immature bone. ## Diagnosis Clinical examination and radiographs. Scintigraphy detects early stress remodeling. ## Treatment Rest and modification of the training schedule. Complete fractures may require internal fixation. ## Recovery and Prognosis Good for incomplete stress fractures with appropriate rest. Complete fractures have a more guarded outlook. ## Prevention Gradual introduction of high-speed work. Signs include: soreness over the dorsal cannon after fast work; heat and swelling; radiographic stress fracture or periosteal reaction
## Overview Incomplete or stress fractures of the radius occur in racehorses from repetitive loading. They cause forelimb lameness and carry a significant risk of propagating to a complete, catastrophic fracture if the horse continues to train or race. ## Causes Cyclical fatigue. ## Diagnosis Radiographs and scintigraphy. Clinical lameness after fast work. ## Treatment Strict rest. Complete fractures of the radius in adults have a very poor prognosis. ## Recovery and Prognosis Good for incomplete fractures that are rested. Complete fractures are usually fatal. ## Prevention Careful monitoring of young racehorses and modification of training when soreness appears. Signs include: forelimb lameness after fast work; radiographic or scintigraphic stress fracture of the radius
## Overview Physitis is inflammation of the growth plates (physes) in young horses, often related to rapid growth, nutritional imbalance, or excessive exercise. It causes warm, painful enlargement around the growth plates, most commonly at the distal radius, distal metacarpus/metatarsus, and distal tibia. Lameness may be present. ## Causes Rapid growth, high-energy diets, conformational stress, or trauma. ## Diagnosis Clinical appearance and radiographs showing physeal irregularity or flaring. ## Treatment Dietary adjustment (reduce energy), restricted exercise, and anti-inflammatories. Most cases resolve with management. ## Recovery and Prognosis Good with appropriate management. ## Prevention Balanced nutrition and controlled growth rate. Signs include: warm painful enlargement around growth plates; lameness; radiographic physeal changes in young horses
## Overview Olecranon fracture is a break of the point of the elbow, usually from direct trauma such as a kick or fall. Because the triceps inserts on the olecranon, the horse cannot extend the elbow and presents with a dropped elbow and non-weight-bearing lameness. Surgical repair with plates and screws is the treatment of choice for most displaced fractures and carries a generally good prognosis. ## Causes Direct trauma. In foals, excessive pull from the triceps can also cause fracture. ## Diagnosis Characteristic posture and radiographs of the elbow. ## Treatment Tension-band plating for displaced fractures. Some non-displaced fractures in foals may be managed conservatively. Prognosis is good with internal fixation. ## Recovery and Prognosis Good with appropriate surgical repair. ## Prevention Trauma avoidance. Signs include: dropped elbow; inability to bear weight; swelling at the point of the elbow; cannot extend the elbow
Fractures of the radius are serious injuries that often require surgical repair and carry a guarded prognosis depending on configuration and soft-tissue damage. The olecranon can also fracture, affecting triceps function and elbow extension. Because the bones are fused, the forearm has no rotational capacity, which influences both normal biomechanics and injury patterns.
Severe lameness with swelling of the forearm or inability to bear weight after trauma needs immediate veterinary attention. Do not attempt to walk the horse long distances until evaluated.
See the Radius & Ulna (Left) on our interactive 3D horse model. Open 3D Model