Calcaneal fractures in horses result from external trauma to the limb (eg, from being kicked by another horse or from kicking a fixed object). Severe fractures result in displacement of the superficial digital flexor tendon from where it runs over the plantar aspect of the calcaneus and can involve the sustentaculum tali.
Because only a thin layer of soft tissue covers the calcaneus, fracture fragments occasionally penetrate the skin, resulting in open fractures and increased risk of osteomyelitis and sepsis of the surrounding synovial structures.
Horses with calcaneal fractures typically show moderate to severe lameness. Diagnosis is straightforward on standard radiographic views. Additional flexed lateral and skyline radiographic projections of the tarsus and calcaneus, respectively, are recommended to enable complete assessment of the calcaneus and sustentaculum tali.
Depending on the fracture configuration, the recommended treatment for calcaneal fractures is fragment removal, fixation with screws using lag technique, or plate fixation. Open, comminuted fractures of the calcaneus with involvement of the calcaneal bursa carry a poor prognosis. Fractures of the sustentaculum tali alone are rare, and surgical intervention is recommended because conservative management results in undesirable outcomes.
Small fragments can be removed via a tenoscopic approach to the tarsal sheath. Even with early surgical intervention, the prognosis for long-term athletic function with fractures of the sustentaculum tali is guarded.
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Also see pet owner content regarding disorders of the tarsus in horses.
