Ankle radiographs obtained after trauma can be used to evaluate for fracture and dislocation.
Trace cortices looking for disruption or irregularity. Carefully inspect the tibial plafond, talar dome, medial and lateral malleolus, which are commonly involved in traumatic injury.
Many osseous contours in the ankle overlap, often resulting in fractures that can only be readily identified on a single view. (i.e. lateral process of the talus, anterior process of calcaneus, sustentaculum tali of calcaneus, base of the fifth metatarsal, and posterior malleolus of the tibia)
Assess for traumatic malalignment and ankle syndesmotic injury:
- Examine the medial and lateral ankle mortise on dedicated mortise view for symmetry.
- Check the syndesmotic interval. (normal <6mm between tibia and fibula 1 cm proximal to tibial plafond)
Stress views can reveal ligamentous injury. Fig A and Fig B demonstrate radiographic evidence of deltoid ligament tear.
Familiarize yourself with common locations and patterns of injury involving the ankle and hindfoot with their respective classification systems.
Lateral malleolar fractures
- Weber A- below the talar dome
- Weber B- at tibiotalar joint/tibiofibular syndesmosis
- Weber C- above distal tibiofibular syndesmosis
Stress views may be helpful in identifying ligamentous injury
Medial malleolar fractures
- Can be associated with proximal fibular fracture or syndesmotic injury when seen in isolation
Bimalleolar fracture
- Fracture of distal fibula and medial malleolus
- Alternatively, medial component may be complete tear of deltoid ligament
FINDINGS: Moderately displaced, obliquely oriented fracture of distal fibula with extension of fracture plane to the level of tibiotalar joint. Additional displaced avulsion fracture of distal medial malleolus with widening of medial clear space, suggesting deltoid ligament injury.
Trimalleolar
- Fracture of lateral malleolus, medial malleolus, and posterior malleolus
- Classifications in Brief: Lauge-Hansen Classification of Ankle Fractures. Clin Orthop Relat Res. Tartaglione JP, Rosenbaum AJ, Abousayed M, DiPreta JA. 2015;473(10):3323-3328. doi:10.1007/s11999-015-4306-x
- Simplified Diagnostic Algorithm for Lauge-Hansen Classification of Ankle Injuries. Heitor Okanobo, Bharti Khurana, Scott Sheehan, Alejandra Duran-Mendicuti, Afshin Arianjam, and Stephen Ledbetter. RadioGraphics 2012 32:2, E71-E84
Tibial Plafond aka Pilon Fracture
- Comminuted fracture of the distal tibia, frequently with intra-articular extension
Maisonneuve fracture
- Proximal fibular fracture in the setting of ankle injury, such as an isolated medial or posterior malleolus fracture
Talar body and neck fractures
- May be associated with subtalar, tibiotalor, or talonavicular dislocation
- May disrupt blood supply to proximal talus, increasing risk for avascular necrosis
- On follow up radiographs, look for resorption of subcortical bone at the talar dome which implies osseous resorption from intact blood supply ("Hawkins sign")
Snowboarder fracture
- Displaced lateral talar process fracture
- Difficult to perceive due to superimposed osseous structures
Osteochondral injury of the talus
- Confirm the talar dome is smooth and evaluate for subchondral lucencies
Calcaneal fracture
- High impact injury
- Report degree of depression, comminution, and articular involvement.
Chopart fracture-dislocation
- High impact injury with dorsal dislocation of talonavicular and calcaneocuboid joints
Example report negative for traumatic injury:
FINDINGS:
- No acute fracture or dislocation. The ankle mortise is symmetric. The talar dome is intact.
IMPRESSION:
- No acute fracture or traumatic malalignment.