When evaluating ankle fractures, an accurate assessment of fracture location, appearance, and displacement is critical. Associated soft tissue or ligament injuries are also important to detect for appropriate management of the injury. When evaluating ankle injuries, it is helpful to consider the bones and ligaments as a ring-like structure. The ring is made of the medial malleolus, tibial plafond, distal tibiofibular ligaments (TFLs) and
syndesmosis, the lateral malleolus, lateral ligament complex, talus, and medial ligaments. Breaks in the ring commonly occur at five sites, either alone or in combination (see Fig. 8-1). Breaks in the ring resulting in asymmetry in the position of the talus in the ankle mortise require fracture or ligament injury involving two of these locations (see Fig. 8-2).

Most ankle injuries are the result of inversion (supination) or eversion (pronation) forces. However, the mechanism of injury is rarely pure with rotational, abduction, or adduction forces to the foot and axial loading occurring as well (see Figs. 8-3, 8-4, 8-5, and 8-6). There are multiple classification systems, but the Lauge-Hansen, Danis-Weber, and Orthopaedic Trauma Association systems will be reviewed. Common fracture eponyms will also be listed following the classification section.

The Lauge-Hansen classification is based on the position of the foot and direction of the forces at the time of injury. This system is very accurate in predicting associated ligament injuries. Determining the mechanism of injury is based on the appearance of the fibular fracture and position of the talus. Table 8-1 describes the stages of injury and radiographic features of the Lauge-Hansen classification.

The Danis-Weber classification is based on the location of the fibular fracture. Type A fractures are below the level of the ankle joint. Type B fractures are at the level of the ankle with the distal TFLs intact. Type C fractures are above the ankle joint with disruption of the ligaments and syndesmosis (see Fig. 8-7).

The Orthopaedic Trauma Association classification expands upon the Weber, Lauge-Hansen, and AO (Arbeitsgemeinshaft
fur Osteosynthesefragen) classifications with three major groups (A to C) divided into three subgroups with multiple additional subgroups (see Figs. 8-8, 8-9, and 8-10). The features are similar to the classifications mentioned in the preceding text and when appropriate will be included in Table 8-2.

Chapter 2 contains common fracture eponyms for fractures and ligament injuries involving the ankle.

Talar neck fractures account for 30% to 50% of talar fractures and 6% of all foot and ankle injuries. Fractures are the
result of abrupt dorsiflexion of the foot impacting the talus against the tibia. Injuries typically occur during motor vehicle accidents or significant falls. Supination-lateral rotation injuries may also result in talar neck fracture. Associated fractures are not uncommon. Up to 26% of patients have associated fractures of the medial malleolus and 15% have talar head fractures with associated fractures of the medial and lateral malleoli.

The Orthopaedic Trauma Association classification considers talar neck fractures as extra-articular. A common classification is the Hawkins classification (see Fig. 8-28).

There is a wide range of talar body fractures including osteochondral fractures, talar process fractures, and complex crush or shearing fractures. Table 8-7 summarizes the incidence and mechanism of injury of talar body fractures.

Lateral talar process and talar dome fractures are overlooked on initial radiographs in up to 50% of patients. Talar dome fractures are more common and may involve the lateral or medial talar dome or both simultaneously. Medial lesions are deeper and not always associated with acute trauma (see Fig. 8-29). Lateral lesions are more subtle and flake-like

(see Fig. 8-30). The Berndt and Harty classification is applied to talar dome fractures. Stage I lesions are compressions of the talar dome without associated ligament ruptures and intact overlying cartilage. Stage II lesions are partially elevated fractures. Stage III lesions are complete fractures without displacement and stage IV lesions are displaced. Stage II to IV lesions can be easily overlooked due to the associated ligament injuries.

Talar head fractures are uncommon, although some reports indicate that they account for 3% to 10% of talar fractures. Fractures may be easily overlooked on radiographs. Injuries result from extreme dorsiflexion of the foot or associated with subtalar dislocations when the talar head is impacted against the navicular.

Imaging of talar fractures begins with routine AP, lateral, and oblique views of the foot and ankle (see Fig. 8-31). Both internal and external oblique views of the ankle may be helpful for subtle fractures (see Fig. 8-32). Special subtalar oblique projections have also been described. However, if radiographs are equivalent or fractures are defined, most institutions obtain CT with coronal and sagittal reformatting or three-dimensional
reconstructions to fully evaluate the fracture and articular involvement (see Fig. 8-33). CT is particularly important in subtle injuries. The presence of a joint effusion (best seen on the lateral view) should suggest further imaging (CT or MRI) to exclude subtle injuries to the talar dome or talar processes. MRI is useful for detection of subtle stress injuries, bone bruises, early AVN, and soft tissue injuries (see Fig. 8-34).

Treatment options vary with the type of injury, articular involvement, open wounds, patient condition, and surgical preference. Both closed reduction and open reduction with internal fixation may be used in the appropriate settings.

Treatment of talar neck fractures varies with the extent of the lesion. Type I undisplaced fractures or minimally displaced type II injuries can be managed with cast immobilization for 6 weeks. Open reduction and internal fixation is preferred for failed closed reduction of type II and initial treatment of type III and IV lesions (Fig. 8-31). Twenty-five percent of type III fractures are open, thereby increasing the risk of infection. In this setting, internal fixation with delayed wound closer to 3 to 5 days is preferred.

Complex talar body fractures have a high complication rate with closed reduction (see Fig. 8-35). Therefore, open reduction with internal fixation is preferred to restore articular anatomy and preserve as much function as possible.

Talar dome and process fractures are frequently overlooked. Talar process fractures (lateral or posterior) can be managed with cast immobilization if there is <2 mm of displacement. Comminuted fractures may require removal of the small fragments with internal fixation or major fragments. Talar dome fractures that are undisplaced (types I to III) may be treated conservatively. If closed reduction fails, arthroscopic drilling of type II and debridement of type III lesions should be considered. Displaced fragments (type IV) usually result in chronic symptoms and should be removed (see Fig. 8-36).

Talar head fractures with minimal articular deformity or involving only a small portion of the articular surface may be managed with cast immobilization for 6 weeks. If the fragment is displaced or causes incongruency of the talonavicular joint, open reduction and internal fixation with screws or bioabsorbable pins is preferred (see Fig. 8-37).

Isolated dislocations or those associated with other injuries are managed with immobilization that is in concert with treatment of the other injuries. CT images should be obtained following reduction to fully evaluate the joint spaces and any osteochondral fragments that may not have been initially recognized.

Complications following talar fracture/dislocations include AVN, posttraumatic arthritis, malunion or nonunion, and infection. AVN is common following displaced talar neck fractures and complex talar body fractures. The incidence of AVN is only 0% to 13% with Hawkins type I fractures, but increases to 20% to 58% with type II and 83% to 100% with type IV fractures (see Table 8-8). The incidence of AVN with complex body fractures is 40%. AVN is less common with talar process and talar dome fractures. Radiographs following fractures may demonstrate changes of AVN within 6 to 8 weeks. Normally, there is subchondral osteopenia due to hyperemia. When this is absent or bone sclerosis is evident (Hawkins sign), the area is ischemic (see Fig. 8-38). MRI is more specific and can demonstrate changes earlier (see Fig. 8-39).

Posttraumatic arthrosis involving the tibiotalar and subtalar joints is common following all types of talar fractures. Following complex talar body fractures (Fig. 8-35) the incidence ranges from 48% to 90%. Arthrosis occurs in 54% of patients with talar neck fractures and 50% with talar dome fractures. Serial radiographs are usually adequate for evaluation. However, based on the symptoms and when arthrodesis is considered, CT with coronal and sagittal reformatting is useful for treatment planning purposes.

Fracture healing may be delayed or result in malunion or nonunion. Nonunion occurs in only 4% of patients with

talar neck fractures, although delayed union is common (15%). Delayed union is considered in fractures that have not healed by 6 months. Malunion following talar neck fractures is also common (32%). CT is preferred to evaluate healing in patients with talar fractures.

Infection is a relatively common problem due to the incidence of open wounds associated with talar fracture dislocations. More than 50% of Hawkins type III and IV fractures are associated with open wounds. Infection and skin slough are the most difficult complications to manage. Implant removal and placement of antibiotic spacers may be required for treatment. MRI or combined technetium Tc 99m and labeled white blood cells or antigranulocyte antibodies are useful to define infection. Aspirations can also be used to isolate the organisms.

Extra-articular fractures include all fractures that do not involve the posterior facet. Injuries may be caused by twisting, avulsion, or compression forces. The posterior, anterior, or medial calcaneus may be involved. Patients with anterior calcaneal process fractures often present with symptoms similar to ankle sprain. Therefore, it is not uncommon for these fractures to be overlooked (see Fig. 8-40).

Fractures of the calcaneal body spare the facets, but may result in joint incongruency and articular deformity. Although the prognosis is better than articular fractures, there may still be considerable calcaneal deformity. Fractures of the peroneal tubercle or lateral calcaneal process are uncommon. This injury is usually related to inversion plantar flexion forces or direct trauma. Once again, patients typically present with symptoms of ankle sprain.

Calcaneal tuberosity fractures result from Achilles avulsion and are more common in younger patients and elderly osteoporotic or diabetic patients (see Fig. 8-41). Fractures of the medial calcaneal process are more likely the result of vertical shearing forces than avulsion of the plantar fascia, adductor hallucis, or flexor digitorum muscles.

Two fracture patterns occur with intra-articular fractures due to shearing or compression forces. A shear fracture line

occurs in the sagittal plane involving the posterior facet that may extend to the calcaneocuboid articulation. This fracture separates the calcaneus into sustentacular (anteromedial) and tuberosity (posterolateral) fragments. Compression injuries cause displacement of the anterolateral calcaneus into the angle of Gissane. This results in loss of calcaneal height, widening of the calcaneus, and articular deformity in the posterior facet.

Calcaneal fracture classifications have been modified over the years from the Rowe, Essex-Lopresti, Orthopaedic Trauma Association, and in recent years several classifications based upon CT findings, specifically related to the posterior facet. The Sanders classification is useful for correlating image features with prognosis and treatment approaches. With this method the coronal image with the widest undersurface of the posterior talar facet is divided by two lines (A and B) into three columns. The two lines separate the posterior calcaneal facet into three segments—medial, central, and lateral. A third line (C) separates the margin of the posterior facet from the sustentaculum resulting in four potential fragments. The lines are named A, B, and C moving from lateral to medial as the more medial the fracture the more difficult the reduction (see Fig. 8-42).

Almost all calcaneal fractures should be evaluated with CT to exclude articular involvement. Therefore, this classification has more application for imagers than some of the other fracture classifications.

Radiographs should be obtained as the initial screening examination for suspected calcaneal fractures. Lateral and axial projections are obtained. The latter is useful to evaluate calcaneal width although the articulations may not always be identified (see Fig. 8-43). There are two key measurements that should be made routinely on the lateral radiograph. The Bohler angle (normal 25 to 40 degrees) (see Fig. 8-44) is a useful measurement for evaluating calcaneal height. The angle is formed by a line from the posterior superior calcaneal margin to the upper margin of the posterior calcaneal facet. A second line is drawn from the posterior superior margin of the facet
to the upper margin of the anterior calcaneal process. The crucial angle of Gissane (normal ∼100 degrees) (Fig. 8-44) is formed by lines along the posterior facet and anterior calcaneal process.

CT with reformatting in the coronal and sagittal planes is essential to classify the type of injury and plan appropriate management (see Fig. 8-45). Coronal and sagittal reformatted images are aligned from the axial images along the axis of the talus to best define the posterior facet. Three-dimensional reconstructions can also be obtained although they typically do not add significant new information.

MRI is useful for subtle osseous injuries, such as stress fractures, tubercle, or process fractures (see Fig. 8-46) and to evaluate the soft tissues to exclude peroneal tendon dislocation, tendon entrapment, and compartment syndrome.