The anatomy of the ankle joint

The ankle joint constitutes the articulating surfaces formed by the leg bones and the bones of the hind foot. The joint consists of two parts: The Tibiotalar joint created by the fibula, tibia and talus and the subtalar joint formed by the bones of the hind foot, talus and calcaneus. In most instances however, the term ankle joint is used synonymously with the tibiotalar joint. The ankle has to withstand large rotational and compressing forces, and ankle sprains and fractures are among the most common of all orthopaedic injuries.


Animation describing the anatomy of the ankle joint

Injuries of the ankle

Ankle sprains or soft tissue injuries of the ankle usually occur as minor ligamentous injuries involving the lateral ligaments. However, the severity of the injury depends on the number of ligaments affected, and in more complex injuries, tearing of the ligaments are accompanied by bony avulsions or fractures. By trying to understand the underlying mechanisms of injury, the Danish physician Lauge-Hansen developed a classification system describing ankle fractures. In contrast to other classification systems, Lauge-Hansen does not describe the fracture sustained, but instead classifies injuries based on the position of the foot and the direction of the injurious forces at the moment of trauma.
Lauge-Hansen classified ankle fractures into four groups, and the first name of each group defines the position of the foot at the moment of trauma.



The second name of each group denotes the direction of the injurious force defined by the resulting movement of the foot into adduction, abduction or eversion (external or outward rotation).

Animation describing supination-adduction injuries

Animation describing supination-eversion injuries

Animation describing pronation-abduction injuries

Animation describing pronation-eversion injuries

Animation describing Maisonneuve fractures

Maisonneuve fractures represent a type of pronation-eversion injury that deserves particular attention, as these injuries are easily overlooked when there are no skeletal injuries present at plain ankle radiographs.

Treatment

Primary treatment is common to most injuries and includes ice bandage, compression and elevation. Thereafter ankle injuries are treated surgically or by immobilizing the ankle using a cast or a brace. The exception being minor ligamentous injuries that are usually best treated functionally, allowing early mobilization and focusing on balance and coordination exercises. Taping or bracing may provide additional support and can be used to protect against new injuries during the initial phase. Undisplaced fractures are usually treated by immobilizing the ankle for six weeks, although there are notable exceptions such as Maisonneuve fractures and lateral bony avulsions. Displaces fractures are generally treated surgically with open reduction and internal fixation.


Animation describing surgical treatment of ankle fractures