Ankle Dislocation in Emergency Medicine Clinical Presentation

Updated: Apr 28, 2016
  • Author: James E Keany, MD, FACEP; Chief Editor: Trevor John Mills, MD, MPH  more...
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Presentation

History

A detailed history regarding the mechanism of injury often helps predict the type of injuries to expect. Furthermore, an understanding of the injury mechanism aids treatment, since an opposite force is required in reduction of the joint. Because of the inherent stability of the ankle joint mortise and surrounding tendons and ligaments, dislocation is most usually caused by high-energy trauma that causes plantar flexion of the ankle combined with either inversion or eversion stress upon the foot. [1] Four types of dislocations are seen around the ankle joint: posterior, anterior, lateral, and superior:

Posterior

A posterior dislocation in the most common type of ankle dislocation. [8] The talus moves in a posterior direction in relation to the distal tibia as force drives the foot backward. [9] The wider anterior talus wedges back, resulting in forced widening of the joint. This must be accompanied by either a disruption if the tibiofibular syndesmosis or a fracture if the lateral malleolus, occurring most commonly when the ankle is plantar flexed.

Anterior

Anterior dislocations result from the foot being forced anteriorly at the ankle joint.

Typically, anterior dislocation occurs with the foot fixed and a posterior force applied to the tibia or with forced dorsiflexion.

Lateral

Lateral dislocations result from forced inversion, eversion, or external or internal rotation of the ankle.They are associated uniformly with fractures of either (or both) the malleoli or the distal fibula.

Superior

Diastasis occurs when a force drives the talus upward into the mortise. These dislocations usually are the result of a fall from a height. In such cases, the patient should be evaluated carefully for concomitant spine injury and fracture of the calcaneus.

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Physical

Inspection of the ankle reveals significant edema with deformity ranging from trace to obvious. Tenting of the skin by the malleoli may be noted.

Palpation of the joint reveals tenderness along the joint line, corresponding to areas of capsular or ligamentous disruption.

In associated fractures, tenderness, deformity, or tenting proximal to the joint may be seen.

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Causes

Possible risk factors that may predispose a patient to dislocation include the following: joint hyperlaxity, internal malleolar hypoplasia, peroneal muscle weakness, and a history of prior ankle sprains. [1]

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Complications

Complications of ankle dislocation may include the following:

  • Nonunion or malunion

  • Synostosis

  • Entrapment of the tibialis posterior tendon or of a fracture fragment

  • Cartilaginous injury

  • Osteochondral fractures of the talar dome

  • Joint stiffness and decreased range of motion (eg, osteoarthritis [10] )

  • Arterial injury (anterior and posterior tibial, peroneal)

  • Compartment syndrome (rare)

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