RadioGraphics 2012; 32:535-536
Heitor Okanobo, MD, Bharti Khurana, MD , Scott Sheehan, MD Alejandra Duran-Mendicuti, MD , Afshin Arianjam, MD , Stephen Ledbetter, MD, MPH
In 1950, Lauge-Hansen described a classification system developed on the basis of the mechanism of injury that described more than 95% of all ankle fractures. The Lauge-Hansen classification system is useful to guide treatment because it helps determine which forces to apply to obtain and maintain closed or open reduction of an ankle fracture. Ankle injuries occur in a predictable sequence that allows a logical understanding of their classification once the injury mechanism is recognized. Thus, a specific location or appearance of the fracture and soft-tissue injuries at imaging allows radiologists to translate imaging information into a traumatic mechanism.
To classify an injury according to the Lauge-Hansen system, three radiographic views (anteroposterior, mortise, and lateral) of the ankle are necessary, and the follow-ing factors must be evaluated: the position of the foot (ie, supination or pronation) at the time of the traumatic event and the direction of the deforming force (abduction, adduction, or external rotation); 13 subgroups were created on the basis of these two factors. Injuries occur in a predictable sequence, and stages may not be skipped. If the force ceases at some point in the sequence, the incomplete injury results in a different classification (20). The stages in any subclassification of the Lauge-Hansen system are the sum of the findings of the previous stages.
An efficient approach to classifying fractures is to identify the presence of a fibular fracture and determine which type of fracture is seen (Fig 1). Oblique fractures extend upward from medial to lateral and are associated with pronation abduction, transverse fractures extend parallel to the talotibial joint line and are associated with supination adduction, and spiral fractures extend upward from anterior to posterior and are related to supination external rotation. Fibular fractures may also be seen above the level of the plafond, usually 6 cm from the joint. In most cases, such fractures are related to pronation external rotation.
Once the type of fibular fracture is determined, the second step is to identify ad-ditional injuries such as posterior or medial malleolar fracture and widening of the tib-iofibular space, medial mortise, or lateral mortise. In the absence of a fibular fracture and the presence of medial malleolar fracture, the fracture may be classified as vertical supination adduction stage II, oblique pronation external rotation, or transverse pro-nation abduction (Fig 2). In the absence of both lateral and medial malleolar fractures,