Lauge-Hansen Classification

The Lauge-Hansen classification system describes ankle fractures as rotational-based injuries. The system was developed by applying rotational deforming forces to cadaveric ankles fixed at the tibia.

Four injury patterns are described based on the position of the foot at the time of injury (supination or pronation) and the direction of the deforming force (adduction or external rotation): supination-adduction, supination-external rotation, pronation-abduction, and pronation-external rotation. Each injury pattern, in turn, has different stages of injury.

Supination-Adduction

A supinated foot experiences forceful adduction without rotation. Stage I injury is tear of the lateral collateral ligaments (anterior talofibular, posterior talofibular, and calcaneofibular ligaments) and/or a transverse fracture of the fibula.

With increasing adduction, the talus is displaced medially, resulting in a vertical fracture of the medial malleolus (Stage II). Often, there is an impaction injury at the medial tibial plafond as well. The sine que non of this injury pattern is the vertical fracture of the medial malleolus, as the lateral component of the injury may be entirely ligamentous and radiographically occult.

Animations of supination-adduction injuries.

Supination-External Rotation

This is the most prevalent ankle fracture pattern. The supinated foot is exposed to an external rotation force, resulting in a shearing force to the fibula and an avulsive force to the medial osteoligamentous complex.

Four stages of injury have been described. Stage I injury represents rupture of the anterior tibiofibular ligament or avulsion fractures at one or both of its sites of attachment (Chaput tubercle of the tibia and Wagstaffe tubercle of the fibula).

A stage II injury includes the above plus an oblique fracture of the fibula. The fibular fracture is minimally displaced, oriented inferiorly in the postero-anterior direction, and located at the level of the syndesmosis.

Stage III injuries include the above injuries plus either a rupture of the posterior tibiofibular ligament or posterior malleolar fracture.

Stage IV injuries include the above plus a medial injury: either disruption of the deltoid ligament or a transverse fracture of the medial malleolus.

Radiographically a stage IV injury without posterior or medial malleolar fractures can resemble a stage II injury. Some advocate getting stress views to differentiate the two. Other findings that can help include anterior or posterior subluxation of the talus, shortening of the fibula (> 2 mm), and lateral subluxtion of the talus on unstressed views.

Animations of supination-external rotation injuries.

Pronation-Abduction

These injuries occur when a pronated ankle is exposed to an aBduction force. Three stages have been described. Stage I injuries are characterized by one or both of the following: transverse medial malleolus fracture and deltoid ligament rupture.

Further abduction results in a stage II injury, driving the talus laterally and resulting in rupture of the anterior and posterior tibiofibular ligaments or avulsion fractures at their attachment sites.

Stage III injuries represent further abduction forces causing a fracture of the fibula. The fracture usually occurs 5 cm to 7 cm above the tibiotalar joint and can be transverse, comminuted, or have a lateral butterfly component.

Stage II fractures that involve lateral ligamentous injury without an avulsion fracture can mimic isolated medial malleolar fractures or medial malleolar fractures due to direct trauma. Stress radiographs are helpful in this regard.

Animations of pronation-abduction injuries.

Pronation-External Rotation

These injuries occur when the pronated foot experiences an external rotation force. As in pronation-abduction injuries, the medial osteoligamentous structures are injured first. Four stages of injury have been described.

Stage I injuries involve either a transverse medial malleolar fracture or deltoid ligament rupture. Further external rotation results in a stage II injury: rupture of the anterior tibiofibular ligament or avulsion fracture at its attachment site (Chaput tubercle).

Stage III injuries involve injury to the syndesmosis and a typically spiral fracture of the fibula. A variant of the stage III pronation-external rotation injury is the Maisonneuve fracture.

Further external rotation is described as a stage IV injury, with fracture of the posterior malleolus or rupture of the posterior tibiofibular ligament.

Animations of pronation-external rotation injuries.

References

Lauge-Hansen N. Fractures of the ankle. II. Combined experimental-surgical and experimental-roentgenologic investigations. Arch Surg. 1950 May;60(5):957-85.