43 Ankle Fractures and Dislocations
Ankle fractures and fracture dislocations are the most frequent intra-articular fracture of the weight-bearing joints. Approximately 70% of ankle fractures are unimalleolar, 20% bimalleolar, and 10% trimalleolar (▶Video 43.1).
History and physical examination
Mechanism of injury (typically rotational or abduction/adduction), ability to bear weight following injury, location(s) of pain, and prior injuries to ankle.
Comorbid conditions are particularly relevant including diabetes mellitus, peripheral vascular disease, and preoperative ambulatory status.
Inspection—look for swelling, blistering, and abrasions. The soft-tissue envelope around the ankle can be tenuous, so definitive fixation may be delayed to allow soft-tissue recovery.
Palpation: entire length of the tibia, fibula, and foot should be palpated for tenderness. Pain over the proximal fibula may suggest Maisonneuve’s fracture, a proximal third fibular fracture with an associated syndesmotic injury, and medial malleolus fracture or deep deltoid ligament rupture.
Vascular examination: posterior tibial artery (posterior to the medial malleolus) and dorsalis pedis artery (lateral to the extensor hallucis longus tendon).
Typically evaluate dorsal foot (superficial peroneal), plantar foot (tibial), and first web space (deep peroneal) sensation.
Motor function is difficult to evaluate in a fracture situation, but assessing toe flexion and extension is usually possible.
Anatomy (▶ Fig. 43.1 )
Fibula—slightly posterior to the tibia at the ankle; forms the lateral malleolus.
Tibia—forms the medial and posterior malleoli:
i. Medial malleolus has an anterior and posterior colliculus with an intercollicular groove, where the deltoid ligament attaches.
ii. Incisura: notch in distal tibia where the fibula rests. The notch is formed by anterior (Chaput’s) and posterior (Volkmann’s) tubercles, which serve as attachment sites for the anterior and posterior inferior tibiofibular ligaments.
iii. Plafond—distal articular surface of tibia. Plafond and malleoli form the ankle mortise with the talus.
Talus—wider anteriorly than posteriorly. The dome is mostly covered with articular cartilage and is housed in the ankle mortise. It is composed of dense bone, which is generally not injured in ankle fractures.
Ligaments (▶ Fig. 43.1 ):
Syndesmosis—composed of four ligaments between the distal tibia and fibula, which allow small amounts of motion. Syndesmotic injury is known as a “high ankle sprain”:
i. Anteroinferior tibiofibular ligament (AITFL):
Attaches to the anterior (Chaput’s) tubercle on the anterolateral tibia and Wagstaffe’s tubercle on the anterior fibula.
Weaker than the posteroinferior tibiofibular ligament (PITFL) and ruptures more frequently than avulses.
Attaches to posterior (Volkmann’s) tubercle on posterolateral tibia.
Stronger than the AITFL and avulses more frequently than ruptures.
iii. Transverse tibiofibular ligament/inferior transverse ligament (TTFL/ITL). Just inferior to PITFL.
iv. Interosseous ligament (IOL). Located between AITFL and PITFL, continuous with the interosseous membrane proximally.
Medial collateral ligament (MCL or deltoid ligament)—important restraint to external rotation:
i. The superficial component connects the anterior colliculus of the medial malleolus with the navicular, talus, and calcaneus.
ii. The deep component is mostly transverse and practically intraarticular, and connects the posterior colliculus of the medial malleolus to the talus. It is the strongest component and primary stabilizer, and can avulse the medial malleolus before tearing.
Lateral collateral ligament—all the components attach to the lateral malleolus:
i. Anterior talofibular ligament (ATFL):
Primary inversion restraint during plantar flexion.
Most commonly injured ligament in low ankle sprains.
ii. Posterior talofibular ligament (PTFL).
iii. Calcaneofibular ligament—primary inversion restraint during dorsiflexion.
Indications to obtain plain radiographs—history of frank dislocation, inability to bear weight following the injury, palpable tenderness of either malleolus.
Anteroposterior (AP), lateral, and mortise views are required:
i. Mortise view—acquired by internally rotating the leg and foot 15 to 20 degrees until malleoli are equidistant from the image detector; it improves visualization of the joint space.
ii. External rotation and gravity stress views assess integrity of the deltoid ligament.
External rotation stress view—the mortise view taken while the foot is manually rotated externally (▶ Fig. 43.2 ).
Gravity stress view—this is an AP view taken with the patient in the lateral decubitus position, with the medial malleolus pointing upward, and without ankle support.
Normal measurements—medial clear space (< 5 mm), lateral clear space (< 5 mm), tibiotalar clear space (< 5 mm), and tibiofibular overlap (> 10 mm; ▶ Fig. 43.3 ).
CT may be used for evaluating syndesmotic injuries, loose bodies, and for preoperative planning of complex injury patterns such as trimalleolar and severe fracture dislocations.
MRI may be useful for soft-tissue evaluation if the stress examination is equivocal.
Ankle fractures are typically described based on number of malleoli involved (unimalleolar, bimalleolar, trimalleolar).
Classifications commonly encountered in the literature: Lauge–Hansen and Danis–Weber.
Lauge—Hansen: describes a pattern of injury progression based on which structures are under tension (▶ Fig. 43.4 ). Supination initially places lateral structures under tension, and pronation initially places medial structures under tension. There are two terms for each pattern.
i. First term—position of ankle during injury.
ii. Second term—direction of force applied to ankle:
Supination-external rotation (SER): ATFL disruption  → oblique fibula fracture  → PTFL rupture or posterior malleolus avulsion  → medial malleolus transverse fracture or deltoid disruption .
Supination-adduction (SA)—talofibular sprain or distal fibula avulsion  → vertical medial malleolus fracture .
Pronation-abduction (PA): medial malleolus avulsion fracture or deltoid disruption  → ATFL disruption  → transverse or comminuted fibula fracture .
Pronation-external rotation (PER)—medial malleolus transverse fracture or deltoid disruption  → ATFL disruption  → high oblique fibula fracture  → PTFL rupture or posterior malleolus avulsion .
Danis–Weber—based on the level of fibula fracture (▶ Fig. 43.4 ):
i. Type A occurs distal to the plafond, and the syndesmosis is usually stable.
ii. Type B occurs at the plafond, and syndesmotic stability cannot be predicted.
iii. Type C occurs proximal to the plafond, and the syndesmosis is usually unstable.