Chapter 22: Ankle

Ankle injuries are common and account for 30% of all sports injuries.¹ In the emergency department (ED), ankle injuries represent 12% of traumatic injuries. Ligamentous injuries are more common than fractures by a ratio of 5:1.² A thorough understanding of the functional anatomy, fracture patterns, and soft-tissue injuries is important to the emergency physician.

Anatomy

The ankle is composed of the distal ends of the tibia and the fibula that form a mortise into which the talus fits. The ankle has been described in the past as a hinge joint, but it more accurately resembles a saddle joint.³ The talar dome or saddle is wider anteriorly than it is posteriorly (Fig. 22–1). With dorsiflexion, the talar dome fits snugly into the ankle mortise, yielding greater stability when compared with plantar flexion (Fig. 22–2). With this in mind, it is easy to see why most ankle injuries occur when the ankle and the foot are in plantar flexion.

The only “pure” motion occurring at the ankle joint is plantar and dorsiflexion. Inversion and eversion take place at the subtalar joint formed by the talus and calcaneus. The subtalar joint is very strong, with firm ligamentous support, and the talus should always be thought of as moving with and in the same direction as the calcaneus. Because of the strength of the calcaneotalar joint, most inversion–eversion stresses injure the ankle joint rather than the subtalar joint.

To understand the disorders that occur around this crucial joint, the emergency physician must have a good knowledge of the fundamental soft-tissue structures that surround it. These structures are best divided into three “layers” surrounding the joint. The deepest layer is the capsule, which contains the ligaments of the ankle; the middle layer includes the tendons, which traverse the joint to reach the foot; and the most superficial layer is made up of the fibrous bands (retinaculi), which hold the tendons in place as they act on the foot.

Capsular Layer

The capsule surrounds the ankle joint. It is weaker anteriorly and posteriorly, but is strengthened laterally and medially by ligaments. The anterior ligament is thin, connects from the anterior tibia to the neck of the talus, and is commonly involved in extensive tears of the lateral ligaments. The posterior ligament is shorter than its anterior counterpart and extends from the posterior tibia to the posterior talus.

The lateral ligaments are the most commonly injured ligaments of the body. They are divided into three important components. Extending from the lateral malleolus to the neck of the talus is the anterior talofibular ligament (ATFL), the most commonly injured ligament in the ankle. From the lateral malleolus to the posterior tubercle of the talus is the posterior talofibular ligament (PTFL), and from the lateral malleolus to the calcaneus extends the calcaneofibular ligament (CFL) (Fig. 22–3).

Proximal to the lateral ligaments, the fibula is connected to the tibia by a series of tough fibrous structures together forming what is called the tibiofibular syndesmosis. This syndesmosis is composed of the interosseous ligament that connects the tibia and the fibula throughout their entire length. This ligament is strengthened inferiorly by two thickened fibrous bands: the anterior inferior tibiofibular ligament and the posterior inferior tibiofibular ligament.

The medial ligament is called the deltoid ligament and is a quadrangular structure that has the distinction of being the only ligament in the ankle to contain elastic tissue, giving it the ability to stretch rather than tear. The deltoid ligament is composed of four bands intermingled with each other and extending from the medial malleolus to the navicular, talus, and calcaneus. Two bands of the deltoid extend to the talus, one called the anterior tibiotalar ligament inserting to the neck of the talus and the other called the posterior tibiotalar ligament, which is the deepest of the four structures. The portion of the deltoid that connects from the medial malleolus to the calcaneus is called the tibiocalcaneal ligament and attaches to the sustentaculum tali (Fig. 22–4).

A ligament of importance that is not included in the capsule of the ankle but is involved in injuries of the ankle and the middle part of the foot is the spring ligament. This ligament extends from the sustentaculum tali to the navicular and bridges the gap between the calcaneus and the navicular bones. It functions to give added support to the head of the talus against the weight of the body and is composed of dense fibrous tissue, portions of which resemble articular cartilage.

Tendon Layer

Superficial to the capsule of the ankle are a series of tendons, none of which attach to the ankle per se, but all of which traverse this joint and are important in considering associated injuries to the ankle. These tendons are subdivided into two groups, the extensors and the flexors of the foot. The extensors pass anteriorly to the ankle joint and the flexors pass posteriorly to the medial malleolus. A third group consists of the peroneal tendons, which pass posteriorly to the lateral malleolus (Fig. 22–5A). Synovial sheaths, some up to 8-cm long, surround these tendons.

Retinacular Layer

Superficial to the tendons are three divisions of thick fibrous bands that hold the tendons in place. These divisions follow the same categorization as the tendons and are similarly termed the extensor retinaculum, the flexor retinaculum, and the peroneal retinaculum. The extensor retinaculum is divided into the superior extensor retinaculum and the inferior extensor retinaculum. The flexor retinaculum consists of one fibrous band that courses posteriorly to the medial malleolus. The peroneal retinaculum has two divisions, the superior peroneal retinaculum and the inferior peroneal retinaculum (Fig. 22–5B).

Examination

The motions of the ankle and the foot are described by a number of interchangeable terms (Fig. 22–6).

1. Eversion: External rotation

2. Inversion: Internal rotation

3. Dorsiflexion: Ankle flexion

4. Plantar flexion: Ankle extension

5. Abduction: Lateral deviation of the forepart of the foot on a longitudinal axis through the tibia

6. Adduction: Medial deviation of the forepart of the foot on a longitudinal axis through the tibia

7. Supination: Adduction and inversion

8. Pronation: Abduction and eversion

These motions must be understood before any further discussion of fractures occurring at this joint. We will use these terms in discussing ankle injuries throughout this chapter. In ankle injuries, inversion and eversion forces are common and are directed perpendicularly to plantar or dorsiflexion of the ankle.

Imaging

Routine ankle radiographs include an anteroposterior (AP), mortise, and lateral views (Fig. 22–7). On the AP view, there is overlap of the tibia and fibula. The mortise view is obtained with the ankle internally rotated 15 to 20 degrees. It represents the true AP projection of the ankle as the tibia and fibula are moved into a plain perpendicular to the x-ray beam. In the mortise view, the tibia and fibula do not overlap and the talar dome is visualized best. This is also the best view to detect a Tillaux (Salter–Harris III fracture of the distal tibial physis due to asymmetric closure of the physis) fracture in adolescents because the lateral aspect of the tibia is not obscured by the fibula. The lateral view provides the best visualization of the posterior aspects of the tibia, fibula, calcaneus, and talus.

Ankle radiographs account for 10% to 15% of all traumatic radiographs.^2,4,5 The Ottawa ankle rules were developed to predict fractures and reduce the number of radiographs obtained^6,7 (Fig. 22–8). By using physical examination, the authors detected 100% of all significant malleolar fractures and reduced ankle radiographs by 36%.⁶ Additional benefits to the implementation of this decision rule include decreased costs and decreased waiting times without an effect on patient satisfaction.^8–11

Since inception, this instrument has been validated in multiple clinical settings around the world and can be used by both physicians and nurses.^12–27 A meta-analysis of 32 studies reported a sensitivity approaching 100%, with a reduction in the number of radiographs by 30% to 40%.²⁸ Attempts to validate these rules in children have yielded mixed results.^29–34 In particular, the clinician should proceed cautiously in preschool-age children.³⁴

When a fracture is suspected clinically, but is not present on plain radiographs, the clinician should consider computed tomography (CT). Plain radiographs were only 85% sensitive to detect fractures about the ankle compared with multidetector CT.³⁵

The ankle bears more weight per unit area than any other joint in the body. It is essential for the physician to realize that ankle fractures and ligamentous injuries frequently coexist and any treatment plan must include both types of injuries.

Ankle fractures are divided broadly into those due to rotational forces (i.e., malleolar fractures) and those secondary to axial loading forces (i.e., pilon fractures).

Malleolar Fractures

Many classification systems exist to describe ankle fractures due to rotational forces. The three most common include the Lauge-Hansen, Weber, and the Neer closed ring classification systems.

The Lauge-Hansen classification system was developed in 1949 by Niels Lauge-Hansen. This system took into consideration the position of the foot and the ankle at the time of injury. The first word refers to the position of the foot at the time the injuring force is applied—supination or pronation; and the second word pertains to the direction of the injuring force—external rotation (eversion), abduction, or adduction. Through cadaveric studies, the author found that the sequence of injured structures was similar and reproducible, as the force of injury increased.

With the foot supinated, the lateral ankle structures are stressed. An external rotation or adduction force placed on the ankle results initially in a fracture of the distal fibula. If an external rotation force is applied, the fibula fracture is oblique and distal (Fig. 22–9). Adduction forces result in a distal transverse fibula fracture (Fig. 22–10). Increasing amounts of force cause a posterior malleolus and a medial malleolus fracture (or deltoid ligament rupture). Fracture of the posterior malleolus is the result of avulsion from the posterior–inferior tibiofibular ligament. Supination-external rotation is the most common mechanism of an ankle fracture, accounting for 85% of cases.³⁶

In pronation, the medial structures of the ankle are now under stress. External rotation or abduction forces applied to the pronated ankle result initially in a medial malleolus fracture (or deltoid ligament rupture) and ultimately, as the force increases, a proximal transverse fibula fracture (Figs. 22–11 and 22–12). The pronation-external rotation (PER) fracture of the fibula is above the level of the tibial fibular syndesmosis and results in complete or partial rupture of the syndesmotic ligaments. The fibula fracture in PER injuries may be very proximal at the level of the fibular neck.

The Weber classification system categorizes ankle fractures by the level of the fibula fracture (Fig. 22–13). Class A fractures are distal to the level of the distal tibial fibular syndesmosis. Class B fractures are at the level of the syndesmosis, and class C fractures are proximal to the syndesmosis. Class A fractures were considered stable, not requiring surgical repair, whereas class B fractures were treated by fibular stabilization, and class C fractures required fibular stabilization and syndesmotic repair. This classification system was attractive because of its simplicity and because it was initially thought to guide therapy.

Unfortunately, the Weber classification ignores the medial injury, which is now thought to be of greater importance. Class B fractures, which are most common, only require surgical repair if the medial structures are injured.³⁶ In addition, the level of the fibula fracture did not always predict the need for syndesmotic repair. For these reasons, the Weber classification is rarely used.

The closed ring classification system is easy to understand and apply. In the closed ring classification system, the ankle is thought of as a ring of bone and ligaments surrounding the talus (Fig. 22–14). The ring in this conceptualization is composed of tibia, tibiofibular ligament, fibula, lateral ligaments of the ankle, calcaneus, and the deltoid ligament. A single disruption of the ring, whether osseous or ligamentous, results in a stable injury. If the ring is disrupted in two places, an unstable injury is present. Unstable injuries can involve two bones (e.g., bimalleolar fracture) or a ligament and bone (e.g., lateral malleolus and deltoid ligament rupture). When fracture displacement is present, the clinician should suspect occult ligamentous disruption if it is not apparent initially.^37,38

Examination

The examination should begin with an assessment of the neurovascular status. Pulses, capillary refill, and sensation are tested. Gross deformity of the ankle is noted. The degree of ankle swelling and the presence of blisters or lacerations may affect patient management (Fig. 22–15).

The foot and knee are examined for evidence of associated injuries. The entire length of the fibula is palpated, searching for evidence of a more proximal fibula fracture consistent with a Maisonneuve injury.

The ankle is palpated for tenderness. The emergency physician should direct attention to the medial malleolus following rotational ankle injuries. Tenderness, swelling, or ecchymosis in this area suggests the possibility of injury to the medial structures (medial malleolus fracture or deltoid ligament rupture). If any of these findings are present, the emergency physician must pay special attention to these structures on the plain radiographs. The absence of medial tenderness rules out an acute deltoid ligament tear or medial malleolus fracture.³⁶

Imaging

Routine views including AP, lateral, and mortise views are usually adequate. The mortise view is an AP view with 20 degrees of internal rotation. This view is useful for assessing the joint space and will detect ligamentous injury if widened.

Stable ankle fractures include an isolated distal fibula fracture (Fig. 22–16). Examples of unstable ankle injuries include bimalleolar (Fig. 22–17), trimalleolar (Fig. 22–18), and Maisonneuve fractures (Fig. 22–19). A lateral and medial malleolus fracture is referred to as a two-part ankle fracture (previously referred to as a bimalleolar fracture). When the posterior malleolus is involved as well, the injury is called a three-part ankle fracture (previously called a trimalleolar fracture). A Maisonneuve fracture occurs when the fibula is fractured proximally in combination with a medial malleolus fracture (or deltoid ligament rupture) and disruption of the tibiofibular syndesmosis.

When physical examination findings suggest a medial injury, this portion of the plain radiograph should be scrutinized. A medial malleolus fracture is usually very apparent and may occur as an isolated injury⁵ (Fig. 22–20). Difficulty arises in determining the presence of deltoid ligament rupture. The best criterion for assessing deltoid ligament rupture is the presence of lateral talar shift on the AP or mortise views of the ankle.³⁶ Lateral talar shift is present when the space between the medial malleolus and talus is greater than the space between the talar dome and tibial plafond (Fig. 22–21). This injury is referred to as a two-part equivalent fracture. A three-part equivalent injury pattern may also be seen (Fig. 22–22).

If radiographs are negative and medial malleolus tenderness is present, the injury should either be presumptively treated as unstable, or additional radiographs should be taken. A gravity stress view can help make the diagnosis.³⁹ This AP radiograph is obtained with the leg horizontal to the floor with the medial side up and the ankle suspended over the edge of a pillow (Fig. 22–23). In cadaveric studies, an increase in the talar tilt >15 degrees or talar shift >2 mm occurs when the deltoid ligament is disrupted. Stress x-rays can cause a significant amount of patient discomfort. Advanced imaging (CT or MRI) should be considered to further evaluate the deltoid ligament.

An isolated posterior malleolar fracture has a low incidence and may be difficult to detect on plain radiographs, making this injury a potential diagnostic challenge⁴⁰ (Fig. 22–24). If this injury is suspected, and because the lateral view may underestimate the size of the fragment, a CT scan may be required. Surgery is indicated when more than 25% of the articular surface is involved, there is more than 2 mm of displacement, or there is posterior subluxation of the talus.

Treatment

The ankle is considered stable when the talus moves in a normal pattern during range of motion.³⁵ If talar movement is abnormal, articular cartilage is damaged, degenerates, and leads to premature arthritis. For this reason, the determination of ankle stability is the most important factor to consider when treating ankle injuries. Stable injuries are treated nonsurgically, whereas unstable injuries require operative fixation.

It has been determined that the primary stabilizer of the ankle is not the lateral elements, as proposed by Weber, but the medial structures (medial malleolus, deltoid ligament).^36,41,42 A fracture of the fibula does not result in abnormal talar movement as long as the medial structures are intact.^43–45 Multiple studies have corroborated this fact by demonstrating successful long-term outcomes of isolated fibula fractures managed by closed methods.^46–49

On the contrary, when the medial malleolus is involved (as in a two-part ankle fracture), satisfactory results are obtained in only 65% of patients managed by closed means versus 90% treated operatively.^36,47 Determining stability requires a review of the plain radiographs as well as a thorough physical examination.

Stable injuries require no reduction and have an excellent prognosis. Examples of stable ankle fractures include isolated distal fibula fractures (common) and some isolated distal medial malleolus fractures. Initially, these injuries are treated with a posterior splint (Appendix A–14), crutches, elevation, and ice until the swelling goes down. Definitive management of isolated distal fibula fractures includes a short-leg walking cast or cast boot for 4 to 6 weeks.³⁶ The goal of therapy is protection from further injury and the results are similar, even when a high-top tennis shoe is used for immobilization.⁵⁰

Although most medial malleolus fractures are treated operatively, a small avulsion can be treated nonoperatively if it is distal and minimally displaced.

Unstable fractures that are displaced should undergo closed reduction and splinting in the ED. The definitive management of an unstable ankle fracture is surgery, but an accurate reduction in the ED is important because it prevents further injury to the articular cartilage, allows swelling to resolve more rapidly, and prevents ischemia to the skin.

Analgesia is necessary to perform the reduction. The ankle is usually easily reduced by applying gentle traction in line with the deformity, followed by gradual motion to return the talus into a reduced position. The ankle is splinted immediately to ensure that the reduction is maintained. A posterior mold and a “U”-shaped splint on either side for added support and stability should be used (Video 22–1 and Appendix A–14). Postreduction films to confirm the reduction are obtained. If the reduction cannot be performed (soft-tissue interposition or impacted fragments) or maintained (large posterior malleolus fracture), urgent operative intervention is necessary. Orthopedic consultation should be obtained. More information about ankle fracture–dislocations is provided in the next section.

Although these injuries were traditionally treated surgically on an inpatient basis, a period of outpatient management before operative fixation is becoming common. Indications for admission include patient noncompliance, lack of social support, inability to manage crutches, or significant associated injuries.

The timing of surgery is dependent on several factors including the type of fracture, condition of the soft tissue, and associated injuries. Even when severe soft-tissue swelling, fracture blisters, or abrasions delay surgery, no adverse outcomes are noted.⁵¹

Ankle Fracture–Dislocations

Dislocation of the ankle most commonly occurs in association with an unstable ankle and multiple fractures. These are open injuries in one-fourth of cases. Fracture–dislocations have three times the rate of major complications compared with simple fractures.⁵²

Early reduction of these injuries is encouraged to reduce the incidence of postoperative complications. Fracture–dislocations that are not anatomically reduced may result in osteochondral injury of the talar dome and pressure necrosis of the overlying skin.⁵³ This section will address the relevant part of the examination and treatment of associated dislocations.

Fracture–dislocations of the ankle can be lateral, posterior, anterior, or superior (Fig. 22–25) with lateral ankle dislocation being the most common form seen in ED. These injuries are usually not open and are associated with either a fracture of the medial malleolus or, less commonly, rupture of the deltoid ligament. Posterior and posterolateral dislocations are also common. The mechanism causing posterior dislocations is a strong forward thrust of the posterior tibia, usually secondary to a blow. The patient is usually in plantar flexion when this occurs. Anterior dislocations are less common than posterior dislocations and are almost always associated with a fracture of the anterior lip of the tibia. The mechanism causing this type of dislocation is a force that causes posterior displacement of the tibia on the fixed foot or forcible dorsiflexion of the foot such as occurs during a fall on the heel with the foot dorsiflexed.

Examination

Clinically, there is usually obvious deformity of the foot and ankle. In lateral dislocations, the foot is displaced laterally and the skin on the medial aspect of the ankle joint is very taut (Figs. 22–26 and 22–27A). In patients with a posterior ankle dislocation, the foot is plantar-flexed and has a shortened appearance (Fig. 22–27B). Patient with an anterior dislocation presents with the foot in dorsiflexion and elongated. On examination, the supporting ligaments and capsule are disrupted. Anterior dislocations are associated with loss of a palpable dorsalis pedis pulse due to impingement by the talus.

Imaging

Whenever an ankle fracture–dislocation is suspected, assess the vascular integrity before obtaining radiographs to exclude compromise. If there is adequate perfusion to the foot, an expedited radiograph can be obtained before reduction (Fig. 22–28). There is some evidence to suggest that CT scanning may further aid in operative planning and should be considered in the ED.⁵⁴

Treatment

As stated earlier, early reduction is preferred following closed injuries. Open fracture–dislocations are reduced in the ED only if they are associated with vascular compromise. Anesthesia is administered using procedural sedation with the guidelines outlined in Chapter 2. Intra-articular injection of local anesthetic into the ankle joint may provide enough pain relief to perform the reduction with a small amount of intravenous analgesics and without procedural sedation.

Hip and knee flexion to 90 degrees is recommended in all cases of ankle fracture–dislocations to relax the gastrocnemius–soleus complex and allow for an easier reduction. This is best achieved with an assistant who will hold the patient’s lower extremity at the knee and provide countertraction during the reduction attempt^55,56 (Fig. 22–29).

Lateral fracture–dislocations reductions and involve axial traction with one hand on the heel and the other hand on the dorsum of the foot, while an assistant applies countertraction. Next, simple manipulation medially brings the ankle back into its normal position (Fig. 22–30 and Video 22–2).

Alternatively, the foot and leg can be suspended to allow gravity and the position of the ankle (plantar flexion and inversion) to aid in the reduction. This can be achieved with finger traps or Kerlix wrapped around the first and second toes. A separate weighted IV pole or the pole attached to the stretcher should be used to avoid tipping the pole over. Another technique involves suspending the foot by a piece of stockinette on the leg that is taped to the thigh and runs distal to the toes. Both of these methods also aid in applying the splint following reduction (Fig. 22–31 and Video 22–3).

Posterior fracture–dislocations are reduced by grasping the heel with one hand and the forefoot with the other hand. First, plantar flex the foot while providing additional axial traction with the other hand. Next, the foot is dorsiflexed and the heel is pushed forward while the tibia is pushed posteriorly (Fig. 22–32).

Anterior fracture–dislocations are reduced by dorsiflexing the foot slightly to disengage the talus. Next, axial traction is applied. The foot is then pushed posteriorly back into its normal position, while an anterior force is applied to the distal tibia.

Superior fracture–dislocations (diastasis) are uncommon injuries often associated with articular damage. These cases should be splinted and emergent consultation obtained.

The Bosworth injury is the rare ankle fracture–dislocation that cannot be reduced. This injury results when a fibular fragment is lodged posterior to the tibia.^57,58

Following reduction, the neurovascular function of the extremity should be reassessed. A posterior splint with a U-shaped stirrup along the sides of the ankle is applied with the ankle at 90 degrees (Appendix A–14). Anterior dislocations are immobilized in slight plantar flexion. Because these fractures are usually unstable, care should be taken to avoid redislocation or displacement while the splint is being applied. Gentle molding of the splint while it dries can be used to “fine tune” the reduction. Plaster splint material is preferred to commercially available fiberglass splints. Fluoroscopy is frequently used to confirm the adequacy of the reduction before the patient goes for a formal postreduction radiograph. For lateral dislocations, the joint space at the mortise should be no more than 3 mm.

The patient will require surgical repair, which is almost always indicated following these unstable ankle injuries. Many surgeons prefer early operative treatment, so consultation with an orthopedist before disposition is appropriate.⁵²

Tibial Plafond Fractures

Intra-articular fractures of the distal tibia are referred to as plafond (French for ceiling) fractures. ^5,59 These fractures may be due to rotational forces, but are more common when the ankle undergoes an axial load. An axial load fracture of the tibial plafond is referred to as a pilon (French for pestle) fracture.⁶⁰ Intra-articular plafond fractures represent 1% to 10% of all lower-extremity fractures.⁶¹

Mechanism of Injury

High-energy axial compression is the common mechanism for the majority of these fractures.^59,62 In this mechanism, the tibia is driven down into the talus and results in a comminuted intra-articular fracture of the distal tibia. Low-energy plafond fractures also occur, and are associated with fewer complications because of a lesser degree of comminution and soft-tissue injury.⁶¹ Low-energy fractures of the plafond may be due to rotational forces.⁶³

The position of the ankle at the time of axial impact will create different fracture patterns (Fig. 22–33). If the ankle is dorsiflexed, the fracture pattern may be comminuted or an intra-articular anterior marginal fracture may be apparent. Alternatively, a plantar-flexed ankle will result in a posterior marginal fracture pattern.

Examination

The patient will present with pain and swelling that is initially localized but may later involve the ankle diffusely. The examiner should attempt to elicit an exact mechanism of injury and carefully examine the ankle for focal tenderness or swelling. Approximately 20% of these fractures are open.^59,62 The dorsalis pedis and posterior tibial pulses should be palpated and compared with the uninvolved extremity. Swelling or ecchymosis surrounding the Achilles tendon may indicate a posterior malleolar fracture.

Imaging

Routine views including AP, lateral, and mortise views are usually adequate (Figs. 22–34 and 22–35). Pilon fractures often require a CT scan to fully delineate the extent of injury. CT scan of the ankle is routinely obtained preoperatively and changes the surgeon’s operative plan 64% of the time.^61,64

Associated Injuries

After an axial compression injury, calcaneal and spinal compression fractures may be seen. Compartment syndrome of the leg is also seen after these high-energy injuries.⁵⁹

Treatment

The emergency management of plafond fractures should include ice, elevation, immobilization in a well-padded splint (Appendix A–14) and emergent referral.⁶¹

The definitive management of these injuries varies from casting to open reduction with internal fixation (ORIF), and, more recently, external fixation.^65,66 Nonsurgical treatment is rarely employed and is reserved for low-energy injuries without articular displacement. ORIF can be performed when the fracture is not associated with excessive soft-tissue damage (usually a low-energy mechanism). ORIF following high-energy injuries with extensive soft-tissue injury is associated with a high rate of complications, making external fixation the treatment of choice.^61,67

Complications

Ankle fractures may develop several significant complications. The incidence of severe complications following ORIF of the tibial plafond ranges from 10% to 55%.⁶⁷ Complications include:

1. Traumatic arthritis of the talar mortise (20%–40%). Comminuted tibial plafond fractures or those involving elderly patients are particularly predisposed to develop arthritis.⁶⁸

2. Skin necrosis or wound breakdown following open reduction of high-energy tibial plafond fractures.

3. Malunion or nonunion.

4. Wound infection may be seen after open fractures or following operative repair due to extensive soft-tissue injury.

5. Complex regional pain syndrome.

6. Ossification of the interosseous membrane.

7. Osteochondral fractures of the talar dome.

Ankle Sprains

Sprains are the most common ankle injury presenting to the ED, and perhaps the most commonly mistreated injury confronting the emergency physician. Many physicians have a limited understanding of the “simple sprain,” yet this disorder confronts them more commonly than any other single entity involving the extremities. Inappropriate management of this common injury can result in chronic ankle instability in 30% of patients, further increasing the likelihood of traumatic osteoarthritis.⁶⁹

Sprains account for 75% of all injuries to the ankle.¹ Ankle sprains occur most often in athletes between 15 and 35 years of age involved in basketball, football, and running. Sprains of the lateral ligaments account for the vast majority, followed by the tibiofibular syndesmotic and medial ligaments.

Mechanism of Injury

Sprains are due to forced inversion or eversion of the ankle, usually while the ankle is plantar-flexed.

Inversion stresses account for 85% of all ankle sprains and result in lateral ligamentous injury. As force increases, a predictable sequence of structures is injured (Table 22–1). The lateral joint capsule and the anterior–inferior tibiofibular ligament (ATFL) are the first structures to be injured following an inversion stress. Isolated injury to the ATFL is present in 60% to 70% of all ankle sprains.⁵ With greater forces, a tear of the CFL occurs, and finally, the PTFL is injured. Injury to all three structures is seen in up to 9% of cases.

Eversion injuries to the ankle are much less likely to result in ankle sprains. In addition to the structures listed in Table 22–1, a lateral malleolus fracture is seen much more commonly following an eversion injury⁷⁰ (Fig. 22–9). When the medial structures are injured, avulsion of the medial malleolus occurs more frequently than rupture of the strong and elastic deltoid ligament. As the force increases, the anterior–inferior tibiofibular ligament and the interosseous (syndesmotic) ligament will tear (Table 22–1). Medial ankle sprains account for approximately 5% to 10% of all ankle sprains.

Eversion of the ankle, internal rotation of the tibia, and excessive dorsiflexion may result in a tibiofibular syndesmotic ligament injury. This injury is termed the “high ankle sprain.” In a series of ankle ligament ruptures, in 3% of cases, an isolated syndesmosis rupture was identified.⁷¹ Shoe design has no impact on the rate of ankle sprains.⁷²

Clinical Presentation

Ankle sprains were previously categorized as first-, second-, or third-degree injuries according to the clinical presentation and the instability demonstrated by stress testing (Table 22–2). However, these terms are no longer recommended as they do not specify the ligament or ligaments involved. Minor, moderate and severe are now the preferred way to describe ankle sprains. Minor injuries are easy to diagnose, whereas difficulty exists in distinguishing between moderate and severe injuries.

In a minor ankle sprain, there is stretching of the fibers of the ligament without tear. The patient presents with no functional loss in the ankle and many of these patients often do not seek care, usually treating themselves at home. Patients with minor sprains demonstrate little or no swelling of the ankle, no pain on normal motion of the ankle, and only mild pain on stressing the joint in the direction of the insulting force, usually inversion.

Patients with a moderate ankle sprain are more difficult to diagnose because moderate sprains mean that the ligament is partially torn. This can run the gamut of anything from just a few fibers being torn to tears involving almost the entire ligament with only a few fibers remaining intact. The patient presents with moderate swelling and complains of immediate pain upon injuring the ankle. This is in contrast to patients with a first-degree injury who may not know they had a sprain until the next day or after a period of rest. The second-degree sprain is fraught with complications, including the possibility of ligamentous laxity and recurrent sprains due to instability.

A severe ankle sprain exists when there is a complete tear of the ligament. An “egg-shaped” swelling over the lateral ligaments of the ankle occurring within 2 hours of injury, in most cases, indicates a severe injury of the ankle. It is often difficult to differentiate a moderate sprain from a severe injury without adequate stress testing or advanced imaging.⁷³ Because the ligaments are completely torn, there may be little or no pain, but there is usually swelling and tenderness of the ankle.

Examination

Careful examination of the ankle will give the emergency physician better insight into the ligamentous structures injured following an ankle sprain. If the swelling about the lateral malleolus increases the ankle circumference by 4 cm, then the probability of ligament rupture within the ankle is 70%. Tenderness over the CFL suggests rupture of this ligament in 72% of cases. Likewise, tenderness over the ATFL means that in 52% of cases, the ligament is ruptured. If all three symptoms are present, then there is a 91% chance of major ligament damage.⁷⁴

Stress testing aids in differentiating moderate and severe ankle sprains. Frequently, pain and swelling secondary to the acute injury do not allow stress testing. In these cases, the ankle should be immobilized and the patient kept from weight bearing. Referral for serial examinations improves diagnostic accuracy.⁷⁵

Injection of the ankle may allow performance of stress tests of the acutely injured ankle. This is done by injecting the joint opposite to the side of the injury (usually, medially) and infiltrating 5 to 10 mL of lidocaine. However, diagnostic accuracy is diminished following injection. The inversion stress test, for example, is only 68% accurate with anesthesia compared with 92% without anesthesia.⁷⁶

The anterior drawer test is the first test to be performed because it examines for rupture of the ATFL. If this test is negative, then there is no need to go to the inversion stress test because it requires both the anterior talofibular and the CFL to be ruptured to be positive.

The anterior drawer test of the ankle can be done with the patient either sitting or supine (Fig. 22–36). The muscles surrounding the ankle should be relaxed. The knee should be flexed to relax the gastrocnemius muscle, and the ankle should be held in a neutral position. If the ankle is plantar-flexed, a positive anterior drawer test will be impossible to demonstrate, even if the ligaments are completely disrupted. The examiner places the base of the hand over the anterior aspect of the tibia and applies a posteriorly directed force. At the same time, the other hand cups the heel and displaces the foot anteriorly.⁷⁷ Rupture of ATFL is indicated by mild anterior displacement of the talus. Increasing laxity indicates additional injury to the calcaneofibular and PTFL. The degree of laxity should always be compared with the normal side.

Within the first 48 hours after injury, the anterior drawer test was found to have a sensitivity of 71% with a specificity of 33%. Five days postinjury, the sensitivity improved to 96% with a specificity of 84%.⁷⁵

An inversion stress test (talar tilt test) can be performed to identify rupture of the CFL. We do not recommend performing this test, however, because it can be quite painful and is not necessary in the acute setting. The inversion stress test measures the angle produced by the tibial plafond and the dome of the talus in response to forced inversion. To perform this test, the ankle is kept in a neutral position and the examiner grasps the anterior tibia with one hand and the heel with the opposite hand. The ankle is inverted. A difference of 5% to 10% or 23-degree tilt indicates tears to the ATFL and the CFL.⁷⁵ This examination technique is the same as that required to perform stress x-rays. Pain associated with this technique and the availability of advanced imaging have led to recommendations against stress x-rays in the acute setting. Eversion, in the manner described earlier, detects injury to the deltoid ligaments.

Examination for the detection of a syndesmotic ligament sprain should include the squeeze test.⁷⁷ To perform this test, the tibia and fibula are “squeezed” together at the mid calf. Pain in the ankle and lower leg on compression (in the absence of a fibula fracture) indicates injury to the syndesmotic ligaments. This injury should also be suspected when tenderness is present at the distal tibiofibular joint or pain is produced upon forced external rotation of the ankle.

Imaging

Radiographs of the ankle should be taken in most cases. The Ottawa ankle rules, as described previously, will aid the clinician in avoiding unnecessary ankle radiographs. In some patients with a moderate sprain, one may note a small flake of bone off of the lateral malleolus. This indicates an incomplete tear and is usually associated with a moderate injury to the lateral ligaments. Widening of the tibiofibular clear space to >6 mm suggests a syndesmotic ligament sprain.

Ultrasound is another modality to be used in the evaluation of the ankle sprain patient. The superficial location of the ATFL lends itself very nicely to ultrasound evaluation.⁷⁸

Arthrography may be used to define the extent of ligamentous rupture. The benefit of this technique is controversial, and it is rarely used in the ED. To perform an arthrogram, the ankle is thoroughly prepped and a 22-gauge needle, attached to a 10-mL syringe, is inserted into the side opposite the injury and about 6 mL of contrast material is injected. A 1:1 mixture of Hypaque (50% diatrizoate meglumine and diatrizoate sodium) and sterile water is used. Radiographs of the ankle are then obtained. When ligamentous rupture is present, extravasation will be seen laterally outside of the ankle joint along the lateral malleolus.

Associated Injuries

Osteochondral lesions of the talar dome occur in 6% to 22% of ankle sprains and are easily missed on the initial assessment.⁷¹ This lesion should be suspected when tenderness is present along the anterior joint line with the ankle plantar-flexed. Magnetic resonance imaging (MRI) or CT scan of the ankle will detect these injuries and should be considered in patients with sprains that remain symptomatic for 6 weeks after injury.

Treatment

The initial care of most lateral ankle sprains treated in the ED is similar, but important differences exist.

For the mild sprain, ice packs, elevation, and a functional bandage with early mobilization is the most appropriate treatment. Semi-rigid braces have been found to lead to better functional outcomes than taping or elastic bandages.⁷⁹ Nonsteroidal anti-inflammatory medications provide analgesia and possibly improve outcomes.⁵

Ice should be crushed, placed in a plastic bag, and covered with a thin protective cloth to avoid cold-induced injury to the skin. Ice application is recommended for 20 minutes four to six times a day for the first 2 days. The elastic bandage should extend just proximal to the toes to the level of the mid calf. Elevation of the injured extremity 15 to 25 cm above the level of the heart will facilitate venous and lymphatic drainage.

Weight bearing is encouraged as tolerated. Functional rehabilitation is begun immediately (Fig. 22–37). Return to full activity is usually achievable within a week and patients should be referred to their primary physician.

In moderate sprains, the initial treatment is similar to first-degree sprains except the patient is kept from weight bearing for 48 to 72 hours. After that period, touchdown weight bearing with crutches should progress to crutch walking as soon as possible.² An ankle support, which provides much more stability than an elastic bandage is applied until healing is complete. These supports include lace-up braces, semirigid bimalleolar orthotics, and air splints (Appendix A–18).⁸⁰ Kinesio Tape has shown some promise as an additional modality of treatment as the patient progresses through physical therapy.⁸¹ However, larger studies are needed to further evaluate this therapy.

Prolonged immobilization is a common error in the treatment of these injuries. Because second-degree sprains are stable injuries, rehabilitation should be started with range of motion exercises on day 1. Functional rehabilitation stimulates healing by promoting collagen replacement. Lack of an appropriate rehabilitation program may delay return to activity by months.⁸² Home-based physical therapy programs can be equally effective when compared to patients sent to a physical therapist.^83,84 Rehabilitation of the ankle includes strengthening of the elevators and the dorsiflexors.⁸⁵ Follow-up care with an orthopedist or sports medicine specialist is recommended.

These patients are treated initially with immobilization in a splint for 72 hours with ice, elevation, and referral.⁸⁶ When applying a splint, it is vitally important to keep the ankle out of equinus and in the neutral position.

Physical examination is notoriously difficult immediately following an injury due to pain and swelling. Patients in whom the differentiation between a moderate or severe sprain cannot be certain, it is recommended that the injury be treated as a severe sprain with reexamination after the swelling and pain has subsided. Delayed physical examination 5 days postinjury has been shown to be more accurate than when performed in the first 2 days.^75,87

The definitive treatment of patients with severe injury remains controversial. When significant talar instability is present, surgical repair is recommended by some authors, particularly in the young athletic patient, whereas others recommend early mobilization and physical therapy.⁸⁸ Orthopedic consultation for these injuries, as with any serious injury fraught with complications, is recommended.

Complications

The “simple sprain” can be associated with a high degree of morbidity. Although most patients return to normal activity within 4 to 8 weeks, as many as 20% to 40% of patients after third-degree sprains will have pain that limits their activity for years after the injury.⁷¹

The most common complication, lateral talar instability, will develop in as many as 20% of patients after an ankle sprain. These patients complain of chronic instability of the ankle and “giving way” on running. A majority of patients can be successfully treated with a rehabilitative exercise program and bracing to improve stability. In severe or refractory cases, surgical intervention using a tendon graft to stabilize the joint may be warranted.⁸⁹

Peroneal nerve injury is another common complication following ankle sprains. In one series, 17% of patients with moderate sprains had mild peroneal nerve injuries and 86% of patients with severe sprains injured either the peroneal or the posterior tibial nerve. Thus, impaired ability to walk 5 to 6 weeks after a sprain may be due to peroneal nerve injury. This injury is probably caused by mild nerve traction or a hematoma in the epineural sheath.

Peroneal tendon dislocation or subluxation, syndesmotic injuries, tibiofibular exostosis, sinus tarsi syndrome (subtalar sprain), talar dome osteochondral injuries, and complex regional pain syndrome are infrequent complications of lateral ligament sprains. These entities are all covered in the following sections with the exception of complex regional pain syndrome, which is described in Chapter 4.

Sinus Tarsi Syndrome

The sinus tarsi are spaces on the lateral aspect of the foot between the inferior neck of the talus and the superior aspect of the distal calcaneus. At the depth of this space is the interosseous talocalcaneal ligaments.⁹⁰ When these ligaments are injured after an inversion ankle injury, chronic pain and instability may result. This is termed the sinus tarsi syndrome. A feeling of hindfoot instability and pain while walking on uneven ground is characteristically relieved when at rest. It is difficult to differentiate this condition from a sprain of the ATFL.

This syndrome is a common complication of ankle sprains, which was not recognized in the past.⁹¹ The findings include tenderness at the lateral side of the foot over the opening of the sinus tarsi. This space is palpated inferior to the ATFL. Pain will also occur during walking and supination and adduction of the foot. The diagnosis is confirmed when injection of a local anesthetic into the sinus tarsi relieves symptoms (Fig. 22–38).

Even with stress radiographs, routine radiographic examination of the ankle and subtalar joint typically do not reveal any pathology.

The treatment of this condition includes anti-inflammatory agents, and the patient is fitted with an orthotic. Injection of a local anesthetic and steroid into the sinus tarsi can also be performed and may need to be repeated. When conservative treatment is unable to relieve the pain, surgical treatment of sinus tarsi syndrome can be performed. Subtalar arthrodesis is used if more conservative treatments are not successful.

Talar Dome Osteochondral Injury

“Ankle sprain followed by traumatic arthritis” and “nonhealing ankle sprain” are two common situations that should make the emergency physician consider the possibility of an osteochondral lesion.⁹² There are two locations where the cartilage and bone of the talar dome of the ankle can be injured—the superolateral and superomedial margins. If the fragment dislodges, it grinds into the joint, resulting in irreversible chronic arthritis. Other less common sites for osteochondral injuries are the fibular edge and the posterior articular surface of the navicular.^93,94

Mechanism of Injury

An osteochondral lesion of the superolateral margin occurs secondary to dorsiflexion and inversion. The lateral ligaments may or may not rupture. This injury is seen more commonly in children, due to a greater elasticity of the ligamentous tissue. Superomedial osteochondral fractures occur with plantar flexion, where the narrow talus engages the mortise with a “direct blow.” This injury commonly occurs when a jumper comes down hard on the toes with the foot inverted.

Clinical Presentation

Patients complain of a painful ankle, resistant to treatment, with symptoms persisting longer than a sprain. There is usually no tenderness at the malleoli or over the ligaments during palpation. Patients’ symptoms are aggravated by activity and completely relieved with rest, although there may be slight swelling with a dull ache after excessive walking. The entire examination may be negative except when the examiner palpates the talar dome with the ankle plantar-flexed. Point tenderness is elicited in this area. A synovitis may occur in the ankle joint with recurrent swelling. The most common site of injury in trauma is the posteromedial aspect of the talar dome.⁹⁵ Local anesthetic injection of the joint relieves the pain.

Imaging

Radiographs of the ankle may show a crater or a particle of bone that appears opaque, surrounded by radiolucency (Fig. 22–39). The best view to demonstrate a lateral lesion is an AP view with dorsiflexion of the ankle and 10 degrees of internal rotation. For medial lesions, the AP view is obtained in plantar flexion. Small lesions are not detectable with plain radiographs. Increased sensitivity is obtained using bone scanning, CT scan, or MRI.⁹⁶

Treatment

The patient should be referred for orthopedic consultation because traumatic arthritis is the sequel to delayed care. If this diagnosis is made in the ED the patient should be placed in a posterior leg splint and be nonweight bearing.⁹⁷ When treatment is delayed for more than 1 year, outcome is poor in most cases. Arthroscopy with debridement and removal of loose fragments offers the best opportunity for a good functional outcome.⁷¹

Talotibial Exostosis

Exostosis is the formation of a bony growth at the site of an irritative lesion or in response to direct trauma. Exostosis occurs in the anterior ankle due to repetitive trauma, usually in athletes.

In the normal ankle, the distal anterior aspect of the tibia is round and there is a sulcus at the neck of the talus. As the ankle dorsiflexes, the anterior border of the tibia comes in contact with the sulcus (Fig. 22–40). After repetitive trauma, exostosis at the talar sulcus and anterior–inferior margin of the tibia may form. A third less common site is at the medial and lateral malleolus because of direct trauma from the talus following sprains.

A large number of patients have exostosis that is asymptomatic. In others, pain is present at the anterior aspect of the ankle after activity, and the only finding is exostosis. In most patients, the primary complaint is a decreased activity level, and pain is present only on extreme dorsiflexion of the ankle. On examination, the physician will note some swelling of the anterior aspect of the joint with tenderness to palpation and increasing pain on hyperextension of the foot.

One must differentiate this condition from osteophytes that are a response to degenerative processes in the joint. In exostosis, there is no degeneration of the joint or chronic changes noted.

Treatment is usually conservative. Rest, activity modification, and physical therapy are attempted first. If symptoms continue, arthroscopic debridement is frequently curative.⁷¹

Peroneal Tendon Dislocation

The tendons of the peroneus longus and brevis muscles course down the posterior aspect of the fibula and attach to the base of the first metatarsal and fifth metatarsal, respectively. These muscles act to evert and plantar flex the foot. The tendons are held in place behind the fibula by the superior and inferior peroneal retinaculum. Subluxation or dislocation occurs after injuries that disrupt the peroneal retinaculum (Fig. 22–41).

This condition may be due to laxity of the retinaculum or a congenitally absent retinaculum, but most cases occur after a sudden and forceful contraction of the peroneal muscles in association with forced plantar flexion and inversion of the foot and ankle.⁹⁸ During injury, the peroneal muscles contract reflexively and overcome their fibro-osseous sheath, causing the tendons to pass anteriorly.⁹⁹

This condition is sometimes confused with an ankle sprain; however, physical examination clearly distinguishes the two, based on tenderness behind the lateral malleolus following peroneal tendon injuries. Some factors may contribute to the frequency of dislocation, such as a convex or flat posterior surface of the distal fibula and a bifid peroneus brevis muscle. The condition may be acute or chronic in its presentation.⁹⁸

Clinical Presentation

The patient with acute subluxation will give a history of having sustained a blow to the back of the lateral malleolus, while the foot was taut in dorsiflexion and eversion. A snap may be heard or felt associated with severe pain initially that quickly improves. On examination, there is tenderness directly over the peroneal tendons. Tenosynovitis of the peroneal tendons will result in tenderness in the same location, but the history should help distinguish from peroneal retinaculum injury. A complete rupture of the retinaculum is distinguished from an incomplete rupture by noting the tendon ride up over the malleolus when the patient actively everts the ankle.

In patients with chronic subluxation, there is a history of slipping of the tendon with eversion of the foot. There is less pain than in the acute form and the patient usually complains of a dull ache and the sensation of the tendon subluxating as it slips out of its normal position.

Treatment

The patient should be placed in a posterior splint (Appendix A–14) with a compression dressing over the lateral malleolus to stabilize the peroneal tendons in their functional position.¹⁰⁰ They should remain non–weight-bearing with crutches and receive orthopedic referral.

The definitive management is controversial. Most physicians recommend surgical treatment over conservative treatment in a cast for 6 weeks. In one large study, 74% of patients treated conservatively had to return for surgical correction at a later date.⁹⁸

Tenosynovitis

The most common tendons involved in tenosynovitis around the ankle are the (1) posterior tibial, (2) peroneus longus, (3) anterior tibial, and (4) flexor hallucis longus. The Achilles tendon is also commonly involved, but will be covered in Chapter 23. There are two types of tenosynovitis: stenosing and rheumatoid. Stenosing tenosynovitis is common at the inferior retinaculum of the peroneal tendon with thickening of the sheath noted on examination. Rheumatoid tenosynovitis more commonly presents medially, involving the posterior tibial and flexor hallucis longus tendons.

Clinical Presentation

Dysfunction can be acute or chronic.¹⁰¹ Most commonly, an acute tenosynovitis is present secondary to overuse. Chronic tenosynovitis, which is usually found in nonathletic patients, is associated with tendinosis and structural changes.¹⁰² Localized swelling and tenderness is usually present over the involved tendon.¹⁰⁰ With continued use, partial or complete tears of the tendon may result.

Patients who have tenosynovitis of the tibialis posterior tendon report pain along the posteromedial aspect of the foot and ankle. A patient who has tibialis posterior tendon dysfunction may have an increased valgus posture of the calcaneus and a fullness that is seen just distal to the medial malleolus. Lack of heel inversion usually indicates dysfunction or weakness of the tibialis posterior tendon.¹⁰³ Frequently, patients with this condition are unable to stand on the tiptoe because of pain.

On examination, patients with stenosing tenosynovitis will have a thickened sheath palpated along its course. These patients are usually older than 40 years and have some predisposing occupational trauma. The tendon is tender to palpation and motion increases the pain with either form. Spontaneous rupture can occur, particularly in patients with rheumatoid arthritis or those with some unusual activity.

Treatment

Acute tenosynovitis, when it is mild, can be treated with a decrease in the level of activity. However, if the symptoms are moderate, the foot and ankle is put at rest and anti-inflammatory medication and ice are used. In some cases, immobilization (Appendix A–14) followed by a weight-bearing, below-the-knee cast for 4 weeks may be necessary. Rarely, if symptoms fail to respond after this initial treatment, surgical treatment is necessary in acute tenosynovitis.¹⁰²

Ankle Dislocation without Fracture

Isolated dislocation without fracture is considered a rare injury but has been reported extensively.^104–108 The force required to produce a pure dislocation of the ankle without fracture is generally considered to be high energy, and often these dislocations are open. Predisposing factors include ligamentous laxity, weakness of peroneal musculature, medial malleolus hypoplasia, and previous ankle sprains.¹⁰⁵ Dislocations may be posterior (most frequent), anterior, medial, or lateral. Rotatory dislocation of the talus laterally from the tibiofibular joint without fracture has also been reported¹⁰⁹ (Fig. 22–42).

Pediatric Considerations

Care must be taken when evaluating the pediatric patient. The presence of open physes necessitates a conservative approach to diagnosis and management of ankle injuries. Initial x-rays often do not fully evaluate the physes. Advanced imaging (MRI more so than CT) should be considered in this population.¹¹⁰ Children with suspected Salter–Harris injuries should be discharged fully nonweight bearing until definitive imaging and orthopedic follow-up is obtained.