What is Diaphyseal Fracture of the Third Metatarsal Bone?
Condylar fractures are the cause of 25% of horse euthanasia that occurs at racetracks in America. Despite this, the prognosis for a horse that receives prompt veterinary treatment may be fair to good.
Fracture of the third metatarsal bone (or condylar fractures) is one of the most common fracture injuries in horses and occurs predominately in young race horses. Although this is commonly considered purely an affliction for athletes, there are many causes of fractures in horses. These include horses who may suffer from underlying disease such as osteoporosis that predisposes them to suffering from pathological breaks. Other causes of fracture in horses are injury from trauma such as kicks or collisions.
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Symptoms of Diaphyseal Fracture of the Third Metatarsal Bone in Horses
The main symptom of diaphyseal fracture of the third metatarsal bone in horses is acute lameness occurring 10-15 minutes following racing, high intensity exercise or injury. Signs of fracture may include:
- Uneven or abnormal gait
- Signs of shock such as sweating and elevated heart rate
- Localised swelling may occur
- In open fractures bone protrusion may be visible, with bleeding or exudate seen
- Your horse may become distressed and anxious if they are unable to use their limb and may frantically attempt to stand
- Your horse may resent physical contact or flexion and extension of the affected limb
There are a range of types of fractures that may occur.
- Open or compound fractures – These must be carefully cleaned with debris, often horses suffering from this form of fracture will require aggressive antimicrobial therapy
- Simple fracture – One fracture line in the bone, with no bone displacement
- Incomplete fracture – A shallow break in the bone
- Comminuted fracture – Involving two or more bones that become broken or crushed, there is a risk of this fracture occurring following an initial injury; therefore, care must be taken to prevent the horse from causing further injury
- Displaced fracture – A displacement following a fracture causes the bones to move to an abnormal position
Causes of Diaphyseal Fracture of the Third Metatarsal Bone in Horses
These fractures occur under three main circumstances.
- Fractures caused by traumatic, high energy force such as a kick, fall or collision
- Pathological fracture caused by disease processes that cause the bone to weaken such as osteoporosis, resulting in bones that fracture under normal physiological loads
In addition, repetitive strain injury caused by the bone becoming hypermineralised following repeated high speed exercise and large loads on the metacarpal bones may be a cause. This hypermineralisation causes the bones to stiffen, and reduces their capacity to handle normal load. This can lead to brittle bones prone to forming microfractures. This further reduces the structural integrity of the bone, predisposing the bones to fractures.
Diagnosis of Diaphyseal Fracture of the Third Metatarsal Bone in Horses
Your veterinarian will perform a full clinical examination on your horse. They may watch your horse from a distance first to monitor gait and watch for any abnormalities. As it is typical for horses suffering from this form of fracture to have several bouts of lameness prior to diagnosis, it is vital you discuss your horse’s history with your veterinarian.
When examining your horse sedation and stabilisation of the fracture to prevent further damage to the bone occurring may be required. If your veterinarian suspects a fracture has occurred, radiographs of the bone will be taken. This will allow any fractures to be visualised and your veterinarian to make the diagnosis.
Treatment of Diaphyseal Fracture of the Third Metatarsal Bone in Horses
The treatment plan for your horse will be depend on many factors. Therapy may include:
Conservative treatment may be considered for some animals. If your horse is able to be treated conservatively, your veterinarian will likely put together a walking plan to ensure your horse is having carefully monitored, gentle exercise to promote healing. Your horse may also require monthly radiographs to monitor bone healing.
If this is necessary, this will be done under general anesthetic, with your horse’s vital signs monitored closely throughout the procedure. There are many different approaches to surgical fixation your horse’s surgeon may choose to take, however, commonly small screws are used for this procedure.
Additionally, rest of 4-6 months if an open wound or infected fracture occurs will be prescribed as will antimicrobial therapy and supportive wound care and bandaging.
Recovery of Diaphyseal Fracture of the Third Metatarsal Bone in Horses
There are a range of factors that affect the outcome for horses who are treated for these fractures such as age, weight and complications following surgery. Other factors include whether the fracture is open or closed. and the degree of comminution. Although treatment using plates and screws for rigid fixation may be successful, complications such as infection developing, instable fixation, or increased body weight may prevent recovery.