The ankle is the most frequently injured weight-bearing joint. Ankle fractures are among the most common of all fractures; the annual incidence was found to be 71 to 187 per 100,000 people.^1,2,3 Fractures about the ankle range in severity from a minor malleolar avulsion fracture to a comminuted fracture of the articular surface, with a resulting spectrum of stability and congruity of the mortise. Although an ankle fracture often is considered to be appropriate for introductory surgical training, the evaluation, diagnosis, and decision making required to achieve an optimum outcome can prove to be difficult.

A small incongruity in the ankle leads to dramatic changes in the pressure distribution of the joint surface and subsequently leads to arthritis.^4,5 Even a 1-mm shift of the talus can result in a 40% loss of contact area with the plafond. The goal of treating an ankle fracture is to restore congruity and stability to the ankle and to maintain them through the healing process. Whether this goal is best achieved by surgical or nonsurgical means is best decided by weighing the risks and benefits of the treatment options while taking patient-specific factors into account.

Urgent intervention may be required for an ankle dislocation, open fracture, or acutely evolving neurovascular injury. An ankle dislocation with skin tenting or neurovascular compromise may need immediate reduction after only the most pertinent history and physical examination are obtained. Imaging studies done with the ankle in a roughly reduced position may provide more detail about the fracture pattern than studies with the joint in a grossly deformed state.

Imaging of an ankle fracture should begin with AP, lateral, and mortise radiographic views. A full-length tibiofibular series is helpful for diagnosing a proximal fibula fracture. The radiographs should be used to understand the fracture pattern and detect signs of instability. Any incongruity of the talus and the plafond is a sign of instability. Displacement of the medial or lateral malleolus or a talar shift of less than 2 mm historically was associated with a satisfactory result and was used as a criterion for fracture fixation.¹⁴ On the AP radiograph, tibiofibular overlap of less than 10 mm or a clear space of more than 5 mm suggests a syndesmotic injury.¹⁵ On the mortise view radiograph, a medial clear space that is larger than 5 mm or unequal to the superior clear space suggests a medial-side ligament injury. Tibiofibular overlap of less than 10 mm on the mortise view also may indicate a syndesmotic injury. The lateral radiograph may show a posterior malleolus fracture, malpositioning of the fibula relative to the tibia, and/or talar subluxation. The positioning of the ankle during the radiographic procedure is important; the medial clear space was found to become wider with increasing plantar flexion of the ankle, possibly leading to an incorrect diagnosis of deep deltoid injury.¹⁶ Comparison views of the contralateral side may be helpful for detecting asymmetry or associated instability.

Stress radiographs may be indicated to assess stability if the talus and syndesmosis appear reduced, but the injury mechanism or pattern suggests an unstable ankle. A manual external rotation or gravity stress mortise view radiograph can be used to assess deltoid ligament integrity and talus stability in an isolated lateral malleolus fracture.^12,13,17 With instability, this fracture pattern commonly is called a bimalleolar-equivalent fracture. Similarly, a stress view can be used to assess for syndesmotic injury, as in a proximal fibula fracture with a well-reduced ankle. Widening of the tibiofibular joint with an associated lateral shift of the talus is positive for syndesmotic instability. Evaluation of the syndesmosis may be more sensitive in the sagittal plane than in the coronal plane.¹⁸

CT is essential for evaluating the fracture pattern and planning treatment of an axial-loading injury or a suspected plafond or pilon-type fracture. CT is also beneficial for a complex fracture or a fracture with posterior malleolus fragments.

MRI is useful for detecting ligamentous injury. Although MRI may not be economically feasible for every ankle fracture, it can be beneficial if the diagnosis is difficult. MRI was found to be useful for distinguishing partial and complete tears of the deltoid ligament as well as evaluation of the syndesmotic ligament complex.^19,20

An ideal classification system is reliable, reproducible, useful for treatment decision making, and able to provide prognostic information. Although no system for classifying ankle fractures meets all of these goals, the Lauge-Hansen, Denis-Weber, and AO Foundation-Orthopaedic Trauma Association (AO/OTA) systems are most commonly used.

The Lauge-Hansen classification uses the position of the foot at the time of injury as well as the direction of the force causing the injury to define four types of injuries: supination-external rotation, supination-adduction, pronation-external rotation, and pronation-abduction. Each of these types has four subtypes (I through IV) denoting injury severity. The Lauge-Hansen system is popular but difficult to reproduce. A cadaver study found that a short oblique fracture of the distal fibula can occur with the foot in the pronated position, and a high fibular fracture can occur with abduction of the ankle.²¹ A novel study compared online videotape clips showing the mechanism of ankle fractures with postinjury radiographs showing the same injuries.²² The Lauge-Hansen classification was correctly correlated with supination-adduction-type injuries but had only a 29% correlation with injuries of pronation-external rotation type. The Lauge-Hansen classification system is not ideal for guiding treatment decisions or providing prognostic information. However, because this system correlates the mechanism of injury with the fracture pattern, it may be useful for communicating patterns of injury and guiding closed reduction techniques. Countering the injuring force with a splint, cast, or external fixator may improve the reduction.

The Danis-Weber classification is based on the level of a lateral malleolus fracture. A type A fracture is below the level of the plafond; a type B fracture, at the level of the plafond; and a type C fracture, above the plafond. A type A fracture without a medial fracture probably is an avulsion-type fracture that does not lead to lateral instability of the talus and can be treated nonsurgically. A type C fracture is inherently unstable and may involve the syndesmosis. The stability of a type B fracture is more difficult to assess because it may combine a syndesmotic injury with a deltoid ligament injury or may be a stable injury.²³ A stress radiograph can be helpful in type B fractures.

The combined AO/OTA system uses alphanumeric labels to systematically classify fractures.²⁴ This classification system is reproducible and can be used to describe a wide range of injury types as well as specific fracture patterns. Although the AO/OTA system is useful in data collection and research endeavors, it is cumbersome to use clinically and lacks specific diagnostic and prognostic components.

Reduction and splinting of an ankle fracture should be done in a timely manner. The health of the soft tissue is paramount. Reduction of any dislocation or subluxation will help to alleviate pressure on the skin and subcutaneous tissues, and proper reduction can alleviate any pressure, tethering, or kinking of the neurovascular structures. Reduction helps to alleviate atypical joint contact pressure that can contribute to posttraumatic arthritis. A successful reduction typically depends on recognizing the fracture pattern and reversing the deforming force. For example, the commonly used Quigley maneuver for laterally translated or externally rotated ankle fractures applies a varus and internal rotation force through the first toe.²⁵ The Quigley maneuver consists of rolling the patient onto the affected side and suspending the limb by the great toe to allow the talus to internally rotate and translate medially. An unsuccessful reduction may result from the use of an incorrect technique, inadequate anesthesia, or the interposition of structures such as surrounding tendons or fracture fragments. An open reduction may be needed if reduction with closed methods is unsuccessful.

Timely splinting also is beneficial for soft-tissue preservation. The splint helps hold the reduction, which decreases shear forces on surrounding soft-tissue injury. Incorrect splinting technique can cause serious damage, however. The combination of insufficient padding and the pressures added during molding can create pressure points and lead to ulceration. Excess padding can cause the splint to be too loose, increase the shear forces, and even lead to loss of reduction. A study of plaster splints showed that dipping the plaster in water hotter than 24°C can lead to thermal injury.²⁶ The use of multiple plaster layers, as when excess plaster is folded over at its end or layers are added to create a stirrup or strut, also was found to increase the temperature. The recommended method is to cut the plaster to the exact length needed. Placing the curing splint on a pillow or overwrapping it with fiberglass also can increase the temperature to a dangerous level.^26,27

Routine postsplinting radiography of a minimally or nondisplaced fracture that was not unnecessarily manipulated exposes patients to radiation, increases clinical waiting times, increases health care costs, and does not provide meaningful information.²⁸

The treatment goal for a rotational ankle fracture is healing with the mortise in an anatomic position. Attaining this goal may or may not require anatomic positioning of the fibular fracture. Nonsurgical treatment is appropriate if there is no medial malleolar fracture, the deep deltoid remains competent, and the mortise is stable, as can be
confirmed using an external rotation or gravity stress mortise radiograph. A positive stress test results in lateral translation of the talus and is demonstrated by the medial clear space being larger than the superior clear space. The larger the medial clear space is on a stress radiograph, the greater the likelihood of syndesmotic injury.²⁹ If the mortise stress radiograph is negative, nonsurgical management typically consists of early functional treatment, with weight bearing as tolerated. A soft orthosis, walking boot, or walking cast initially can provide comfort and protection from further injury. Its use can be discontinued as symptoms allow.

Ankle fracture-dislocations are inherently unstable and, after initial closed reduction, typically require open reduction and internal fixation (ORIF) of the malleoli to ensure anatomic healing. A Weber type B ankle fracture with a positive stress radiograph that remains well reduced within the mortise without stress can be considered for nonsurgical treatment. A recent prospective randomized study found that nonsurgically and surgically treated unstable fibula fractures had similar outcomes at 1-year follow-up, although 20% of the patients who were nonsurgically treated had medial clear space widening, and 20% had a delayed union or nonunion suggesting longer follow-up is necessary before concluding reduction and fixation is not beneficial.³⁰

If surgical treatment is indicated, attention to the fibular fracture is the key to restoring ankle reduction and stability. Care must be taken to accurately re-create fibular length, alignment, and rotation. The most common fracture pattern is a Weber type B with a spiral configuration at the level of the distal tibiofibular joint. Effective fixation methods include the use of multiple lag screws, one or more lag screws with neutralization plating, or antiglide plating. Common plating surfaces are directly lateral or posterolateral. Laterally based plates tend to be more prominent because of their subcutaneous location, and posterolateral plates can cause peroneal irritation if placed too distally.

The medial side of the ankle can fail through the medial malleolus or the medial ligamentous structures. The medial malleolus consists of the anterior malleolus, to which the superficial deltoid attaches, and the posterior malleolus, to which the deep deltoid attaches. The clinical significance is that when the anterior malleolus is reduced and stabilized, the deep deltoid, and thus the ankle mortise, may remain incompetent.³¹ Medial malleolar fixation typically consists of two lag screws directed from the tip of the malleolus into the distal tibia after open reduction. Depending on the size of the fragment, one screw, a screw and pin, or a tension band technique can be used. Biomechanical and clinical data indicate that cortical lag screws engaged in the far lateral cortex of the distal tibia provide greater fixation strength than screws ending in the distal tibial metaphysis.³² Although most medial malleolus fractures are transverse, a medially directed traumatic force may create a vertical shear fracture, often with marginal impaction of the distal tibia joint surface at the fracture edge. This fracture pattern requires disimpaction and possibly grafting of any joint irregularity, typically followed by spring plate and screw fixation with screws directed from medial to lateral rather than from the tip of the malleolus (Figure 1). Outcomes research has been unable to show a difference in function based on whether the medial-side injury was ligamentous or bony.³³

Treatment of the posterior malleolus component has received increased attention. The decision to fix the posterior malleolus historically was based on the percentage of the articular surface involved, as measured on a lateral radiograph. A fracture involving more than one-quarter to one-third of the articular surface area or a fracture in which the talus is subluxated posteriorly with the posterior malleolar fragment typically requires reduction and fixation (Figure 2). It is now recognized that a posterior malleolus fracture involving the posterolateral corner of the distal tibia represents avulsion of the posterior tibiofibular ligaments, which are a component of the syndesmosis complex. Thus, reduction and fixation of the posterior malleolar component restores the tension
and competence of the syndesmosis in this fracture type, and it may provide better stability than a syndesmotic screw.³⁴ The posterior malleolus contributes to the posterior lip of the tibial incisura, and reduction and fixation may improve syndesmotic reduction accuracy. The less common transverse-type posterior malleolus fracture typically involves a greater percentage of the articular surface and may extend to the medial malleolus. This fracture typically requires ORIF, either percutaneously or through a direct posterior approach. CT can be used to improve the characterization of the transverse-type posterior malleolus fracture.