The ankle is a hinge joint with the talus sitting in the mortise formed by the distal tibia and distal fibula. Ankle dislocations require forces of great magnitude. Posterior and lateral dislocations are most common, but the ankle can also dislocate medially, superiorly, or anteriorly. A posteriorly dislocated ankle is locked in plantar flexion with the anterior tibia easily palpable. The foot has a shortened appearance with an edematous ankle. Anterior dislocations present with the foot dorsiflexed and elongated. Lateral dislocations present with the entire foot displaced laterally. Ankle dislocations are frequently associated with fractures and may be open.
Management and Disposition
An immediate neurovascular examination should be performed. If vascular compromise is present, the ankle should be emergently reduced, even if it is open. The skin may also be taut and can be at risk for necrosis. If time permits, radiography should include AP and lateral ankle views.
To reduce the ankle, gentle traction is applied to the foot with one hand cupping the heel and the other hand on the dorsal aspect of the foot while an assistant applies countertraction. Neurovascular status should be checked before and after any reduction attempts or immobilization. Reduction usually requires conscious sedation or general anesthesia. Patients should be placed in a posterior splint with immediate referral to an orthopedic surgeon for hospitalization.
These injuries are commonly associated with malleolar fractures and often require open reduction and internal fixation.
Fifty percent of ankle dislocations are open and require surgical debridement.
The subtalar joint may also dislocate and appear clinically similar. The lateral x-ray will show overlap of the talus and calcaneus, while the AP mortise view will show an intact mortise.
The worse the ankle appears clinically and radiographically, the easier it is to reduce due to more severe ligamentous disruption.
Ankle Dislocations. This illustration depicts different types of ankle dislocations. Arrows denote direction of the injury force. (Adapted with permission from Simon R. Emergency Orthopedics: The Extremities. Norwalk, CT: Appleton & Lange; 1987: p 402.)
Posterior Ankle Dislocation. Deformity associate with posterior dislocation. (Photo contributor: Mark L. Madenwald, MD.)
Posterior Ankle Dislocation. The talus is dislocated posteriorly in relation to the tibia. (Photo contributor: Kevin J. Knoop, MD, MS.)
Lateral Ankle Dislocation. The talus is laterally displaced in relation to the tibia. ...