A 44-year-old woman who worked as an emergency medical technician
(EMT) presented to the ED with ankle pain after she twisted her
ankle stepping out of the back of an ambulance.
Her ankle radiographs are shown in Figure 1.
- Is this a single malleolar fracture, a bimalleolar
fracture, or a trimalleolar fracture?
- In which way did the patient twist her ankle to
cause this injury?
There are many types of fracture classification systems. The
simplest schemes describe the injury anatomically. Other classification
systems elucidate the mechanism of injury or are based on treatment
Even though the ankle is a relatively simple hinge joint, there
are a number of different classification systems for ankle injuries.
The most basic classification scheme simply describes the number of
fractures about the ankle—either one, two, or three malleoli.
(The third malleolus is the posterior margin of the distal tibia.)
Although this classification system is straightforward, it oversimplifies
ankle injuries and has little relevance to mechanism of injury or
treatment. In addition, the term “bimalleolar fracture” is
ambiguous because it can be used for fractures of any two of the three
By contrast, the Lauge-Hansen classification system
includes 13 separate injuries divided into four groups (Table 1).
This classification system is based on the mechanical forces responsible
for various ankle injuries. Each injury is classified by two terms:
the position of the foot at the time
of injury (either supinated or pronated), and the direction of the force applied to the
ankle (Figure 2).
Table 1 Lauge-Hansen Classification—Based
on Mechanism of Injury |Favorite Table|Download (.pdf)
Table 1 Lauge-Hansen Classification—Based
on Mechanism of Injury
|Injuries occur in sucessive stages as listed|
|Supination–external rotation, 60%||SER 1||Tear of the anterior–inferior tibiofibular ligament (AITFL)|
|SER 2||Spiral fracture of the lateral malleolus at or above the mortise|
|SER 3||Tear of the posterior–inferior tibiofibular ligament (PITFL)
or fracture of the posterior malleolus|
|SER 4||Fracture of the medial malleolus or deltoid ligament tear|
|Pronation–external rotation, 20%||PER 1||Tear of the AITFL|
|PER 2||Fracture of the medial malleolus or deltoid ligament tear|
|PER 3||Tear of the PITFL or fracture of the posterior malleolus|
|PER 4||High fracture of the lateral malleolus above mortise|
|Supination–adduction (inversion), 20%||SAD 1||Low fracture of the lateral malleolus or lateral ligament
|SAD 2||Oblique fracture of the medial malleolus|
|Pronation–abduction (eversion), <0.5%||PAB 1||Fracture of the medial malleolus or deltoid ligament tear|
|PAB 2||Tear of the inferior tibiofibular ligaments ...|
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