A
AITFL tear, spiral lateral malleolus fracture, PITFL tear, medial malleolus fracture or deltoid tear
B
Medial malleolus transverse fracture, AITFL tear, high fibula fracture, PITFL tear
C
Deltoid ligament tear, AITFL tear, short oblique lateral malleolus fracture
D
Transverse lateral malleolus fracture, vertical medial malleolus fracture
Explanation:The correct option is 'a'. The SER (Supination-External Rotation) pattern is the most common ankle fracture mechanism. The sequence of failure proceeds from anterolateral to posteromedial: 1) Anterior inferior tibiofibular ligament (AITFL) sprain/tear, 2) Spiral/oblique fracture of the lateral malleolus, 3) Posterior inferior tibiofibular ligament (PITFL) tear or posterior malleolus fracture, 4) Medial malleolus fracture or deltoid ligament rupture.
Reference: Lauge-Hansen N. Fractures of the ankle. II. Combined experimental-surgical and experimental-roentgenologic investigations. Arch Surg. 1950;60(5):957-985.