Ankle and Foot Injuries

Background and Importance

The ankle and foot are highly evolved structures designed to support the body’s weight and facilitate locomotion over varied terrain. Pathology related to ankle and foot injuries is often subtle, and diagnoses may be delayed or missed, particularly in cases of multiple trauma.

The ankle and foot are best approached clinically as a single functional unit. Although they are discussed sequentially in this chapter, mechanisms of injury overlap, and a pathologic condition in one location may accompany an associated pathologic condition in another.

Anatomy

The ankle joint is the articulation of the tibia and fibula with the talus. The dome of the talus fits into the mortise formed by the medial malleolus, horizontal articular surface of the tibia (or plafond, French for “ceiling”), and lateral malleolus. Fundamentally, the stability of the ankle depends on the bony and ligamentous integrity of the mortise. The calcaneus is also important for the motion and stability of the ankle ( Figs. 49.1 and 49.2 ).

The ankle is composed of three primary articulations—the inner surface of the medial malleolus with the medial surface of the talus, the distal tibial plafond with the talar dome, and medial surface of the lateral malleolus with the lateral process of the talus. These three articular surfaces are contiguous, lined with cartilage, and enclosed by a single joint capsule. The distal tibia also articulates with the distal fibula just proximal to the talus, forming the distal tibiofibular joint. Collectively, these articulations are termed the talocrural joints.

Three sets of ligaments—the syndesmotic ligament and lateral collateral ligaments (see Fig. 49.1 ), and medial collateral ligaments (see Fig. 49.2 ), together which make up the deltoid ligament—support the ankle joint and are essential to its stability.

Tendons course through the ankle in four anatomic groups ( Fig. 49.3 ). The flexor retinaculum tethers the tendons of the tibialis posterior, flexor digitorum longus, and flexor hallucis muscles behind the medial malleolus. The peroneal retinaculum and tendon sheath tether the peroneus longus and brevis tendons behind the lateral malleolus. The extensor retinaculum tethers the tendons of the tibialis anterior, extensor digitorum longus, extensor hallucis longus, and peroneus tertius over the anterior aspect of the ankle. Posteriorly, in the midline, lie the Achilles and plantaris tendons.

Physiology and Pathophysiology

Ankle movements are multifaceted and often involve more than one joint. The ankle joint complex is made up of the talocrural joints and talocalcaneal (subtalar) joints, which allow movements along several axes of motion. Dorsiflexion (ankle flexed so the toes point cephalad) and plantar flexion (ankle extended so the toes point toward the floor) of the ankle joint occur primarily at the talocrural joints. Motions of the ankle joint in conjunction with the midtarsal joints include inversion (sole of the foot points to the midline), eversion (sole of the foot points away from the midline), abduction (external rotation of the foot), and adduction (internal rotation of the foot), which are rotational movements about the longitudinal axis of the tibia.

The components providing stability to the ankle are best conceptualized as a ring-like structure surrounding the talus ( Fig. 49.4 ). Disruption of one element of this ring does not, by itself, induce instability. Injury to one ring element, however, should prompt careful scrutiny for a second injury. Any disruption of two or more elements causes ankle instability and can significantly affect joint function.

Fractures occur when a deforming force is sufficient to overcome the structural strength of a bone. A bone under tension fractures along the axis of the deforming force. Alternatively, ligamentous rupture or an avulsion fracture can occur at either end of a stressed ligament or tendon, and the mechanism of injury generally causes predictable fracture patterns ( Fig. 49.5 ).

Clinical Features

Carefully eliciting the mechanism of injury can often provide clues to the injuries sustained. The presence of sudden swelling and severe pain in the ankle region suggests serious ligament disruption, hemarthrosis, or fracture, and rapid progression of symptoms may represent more severe injury. Inability to bear weight immediately after an injury often implies a significant pathologic condition. Patient recollection of a “popping” sound should prompt consideration of ligament, tendon, or retinacular rupture but does not necessarily increase the probability of a fracture. Finally, the inciting event causing the ankle injury should be determined and, when necessary, investigated further.

The physical examination of the ankle starts with an assessment of deformity, ecchymosis, edema, and perfusion, followed by active and passive range of motion. Assessment of point tenderness may help localize and differentiate between ligament, bone, or tendon injuries, particularly when the patient is seen soon after injury. Palpation should include the medial and lateral collateral ligaments, syndesmotic ligament, inferior and posterior edges of the medial and lateral malleoli, entire length of the fibula and tibia, anterior plafond, base of the fifth metatarsal, calcaneus, Achilles tendon, and tendons behind the medial and lateral malleoli. In addition, the medial and lateral dome of the talus is palpable with the ankle in plantar flexion. Stress testing of the ankle joint, discussed later, should not be performed until a fracture has been excluded. An evaluation of weightbearing ability should proceed only if clinical suspicion of a fracture is low, the location of tenderness does not indicate the need for plain radiography, or radiographs have ruled out a fracture.

Clinical findings specific to ankle fractures include ankle swelling, obvious deformity, skin abnormalities including lacerations and tenting and, if presenting in a delayed fashion, fracture blisters. Neurovascular compromise may occur, therefore performance of a neurovascular examination distal to the injury is necessary. If the fracture has occurred due to a fall from a height, the ankle injury can mask other injuries, such as lumbar compression fracture, fractures of the pelvis, tibial plateau, or other axial skeleton injuries. Maisonneuve fractures can also cause a neuropraxia to the peroneal nerve. Compartment syndrome is a rare complication following isolated ankle fracture and is usually associated with significant disruptive fracture patterns.

Early operative complications of closed and open ankle fractures include pin site infection, delayed skin necrosis, skin graft rejection, neuropraxia or neurotmesis, and osteomyelitis. Delayed complications of operative and nonoperative treatment include malunion, nonunion, osteopenia, traumatic arthritis, chronic instability, ossification of the interosseous membrane, avascular necrosis, and complex regional pain syndrome.

Differential Diagnoses

There is much overlap in the clinical presentation of skeletal, ligamentous, and tendinous pathologies of the ankle and foot due to the complex anatomy and hence differential diagnoses are broad, especially in subtler presentations ( Box 49.1 ).

Diagnostic Testing

Radiology

The anteroposterior, lateral, and mortise views constitute the standard three-view radiographic series of the ankle. Subtle fractures can be easily overlooked on ankle radiographs, and a standardized approach to radiographic interpretation can reduce the likelihood of missing ankle fractures ( Fig. 49.6 ). The lateral view is useful in identifying an ankle effusion, which appears as a teardrop-shaped density displacing the normal fat adjacent to the anterior or posterior margin of the joint capsule. The presence of an effusion suggests the possibility of a subtle intra-articular injury, such as an osteochondral lesion of the talar dome.

The mortise view, taken with the ankle in 15 to 25 degrees of internal rotation, and the lateral view are the most important for evaluating the congruity of the articular surface between the dome of the talus and mortise. In the mortise view, the lines formed between the articular surfaces should be parallel, the joint space should appear uniform throughout the tibiotalar and talofibular components of the joint, and the medial clear space should not exceed 4 mm (see Fig. 49.6 and Fig. 49.7 ). On the lateral view, any incongruity of the articular space between the talar dome and distal tibia suggests ankle instability, particularly if narrowing of the anterior joint space is present.

Reproducible methods for the radiologic evaluation of syndesmotic diastasis have proven elusive. Plain radiographs are the least reliable method for identifying syndesmotic instability. Rather than rely on standard measurements to evaluate for syndesmotic injury, comparison to the contralateral ankle may be valuable in identifying syndesmotic diastasis. The diagnosis of syndesmotic instability can be difficult in the emergency department (ED) and often relies on advanced imaging, which can be arranged at the time of specialist consultation.

In most cases of isolated blunt ankle trauma evaluated within 48 hours of injury, the Ottawa Ankle Rules (OAR) may be used by clinicians to determine whether ankle or foot radiographs are necessary. The OAR state that an ankle radiographic series is required if there is pain in the malleolar region with any of the following findings:

• • Bone tenderness at the posterior edge of the distal 6 cm or tip of the lateral malleolus

  • Bone tenderness at the posterior edge of the distal 6 cm or tip of the medial malleolus

  • Inability to bear weight (defined as the ability to transfer weight onto each leg regardless of limping) for at least four steps immediately after the injury and at the time of ED evaluation

The OAR further state that a foot radiographic series is required if there is pain in the midfoot region with any of the following findings:

• • Bone tenderness at the navicular bone

  • Bone tenderness at the base of the fifth metatarsal

  • Inability to bear weight for at least four steps immediately after the injury and at the time of ED evaluation

The OAR have a sensitivity approaching 100% for detecting acute malleolar zone ankle fractures and midfoot zone fractures but cannot be applied to subacute or chronic injuries. Although derived in an adult population, the OAR appear to be clinically applicable in pediatric patients older than 5 years. In children younger than 5 years, alternative approaches can be used (see Chapter 170 ). Nurse initiated application of the OAR has proven to have similar sensitivity and reduce wait times in the ED. ^,

The decision rules for foot radiography, although applicable to blunt ankle trauma, apply only to the midfoot zone. The OAR were not designed to be general guidelines for foot radiography and do not apply to the hindfoot or forefoot. Finally, the OAR are not applicable to intoxicated patients or those who are difficult to assess because of head injuries, altered mental status, multiple injuries, or diminished sensation related to neurologic deficits.

Lateral Malleolar Fractures

Lateral malleolar fractures are the most common ankle fracture. Stability of the ankle joint depends on the location of the fracture in relation to the level of the tibiotalar joint, which defines the distal portion of the syndesmotic ligament. The Danis-Weber classification (see Fig. 49.8 ) is useful and predictive of outcome in these types of unimalleolar fractures. This classification groups fractures into three types—A, B, and C. Subgroups exist but do not assist the emergency clinician in prognosticating the necessity of operative repair and are beyond the scope of this chapter.

Lateral malleolar fractures below the tibiotalar joint (Danis-Weber type A) rarely disrupt other bony or ligamentous structures and, in the absence of injury to medial structures, such fractures are unlikely to affect the dynamic congruity of the ankle joint. Uncomplicated Weber A lateral malleolar fractures may be considered part of the continuum of ligamentous ankle injuries and managed with functional bracing or walking boot and weightbearing as tolerated, with orthopedic follow-up within a week to ensure ongoing union. Concomitant tenderness over the deltoid ligament may suggest a biomechanical disruption of both malleoli, an associated fracture of the medial malleolus, or an associated fracture of the posterior malleolus. This injury warrants orthopedic consultation within 48 hours on an outpatient basis, especially if the medial clear space on the mortise view is widened (see Fig. 49.6 ). CT imaging can be useful in such situations because it may identify occult medial or posterior malleolar fractures.

Fibular fractures proximal to the tibiotalar joint line (Danis-Weber type C injury; see Fig. 49.8 ) frequently disrupt the distal tibiotalar syndesmosis and medial structures causing ankle instability. These commonly require orthopedic consultation in the ED, or within 48 hours on an outpatient basis (where the patient is immobilized and made nonweightbearing) for operative intervention.

Treatment of an isolated fibular fracture at the level of the tibiotalar joint (Danis-Weber type B injury; see Fig. 49.8 ) is controversial. Fifty percent of these injuries are accompanied by an injury to the distal tibiofibular syndesmosis causing ankle joint instability, and therefore may require operative intervention. Historically, Danis-Weber B fractures were all treated operatively, but the tendency more recently is to base the decision to operate on the stability of the joint, rather than purely on a radiologic classification system. ^, Tenderness on palpation of the syndesmotic ligament, a positive squeeze test (see soft tissue injury section), or widening of the medial joint space on the mortise x-ray view confirms the need for orthopedic consultation in the ED, or within 48 hours on an urgent outpatient basis (where the patient is immobilized and made nonweightbearing) for consideration of operative repair. Stress x-ray views, which include gravity or manual stressing of the fractured ankle, can identify ligamentous instability and clarify the need for operative intervention but are generally arranged by the orthopedic consultant. If discharged from the ED for urgent outpatient orthopedic follow-up, the patient is placed in a walking boot or noncircumferential splint and made nonweightbearing.

Medial Malleolar Fractures

Medial malleolar fractures are usually the result of eversion or external rotation. These two forces exert tension on the deltoid ligament, causing an avulsion of the tip of the medial malleolus or a rupture of the deltoid ligament. Although they can occur in isolation, medial malleolar fractures are commonly associated with lateral or posterior malleolar disruption. Because of this, identification of a medial malleolar fracture or deltoid ligament injury warrants a careful examination of the entire length of the fibula. Tenderness at any point warrants radiographic evaluation to rule out a proximal fibular fracture, known traditionally as a Maisonneuve fracture ( Fig. 49.9 ). Any medial malleolar fracture requires orthopedic referral for assessment of joint and syndesmosis stability for operative syndesmotic stabilization. An isolated nondisplaced medial malleolar fracture can be treated with casting for 6 to 8 weeks, with nonweightbearing and close orthopedic follow-up on an urgent basis, usually within 48 hours. Any displacement or concurrent disruption of the lateral components of the ankle warrants orthopedic consultation in the ED or on an urgent outpatient basis for consideration of operative management. Rarely, stress fractures of the medial malleolus or distal fibula can be seen, particularly in athletes and runners. Plain radiographs may be nondiagnostic, but radionuclide bone scanning, CT imaging, or MRI—the choice is often influenced by local availability—can establish the diagnosis. These injuries can be treated nonoperatively with nonurgent outpatient orthopedic consultation.

Posterior Malleolar Fractures

Isolated fractures of the posterior malleolus are rare and imply an avulsion of the posterior tibiofibular ligament. These injuries can be associated with proximal fibular fractures and medial and lateral collateral ligament sprains. Treatment usually consists of casting for 6 weeks for nondisplaced fractures in which no associated injury or ankle instability is present. CT scanning is generally used to ensure anatomic reduction prior to conservative management. Fractures involving more than 25% of the tibial surface usually require open reduction and internal fixation (ORIF); however, this is an area of controversy, and displaced posterior malleolar fractures require orthopedics consultation within 48 hours on an urgent outpatient basis (where the patient is immobilized and made nonweightbearing).

Clinical Features

Pilon fractures involve the distal tibial metaphysis and usually are the result of high-energy mechanisms with axial loading of the ankle joint, such as falls from a significant height ( Fig. 49.10 ). Destot first coined the term hammer fracture to describe how the head of the talus drives itself into the tibial plafond and causes a pilon fracture. The primary deforming force is one of axial compression, and the position of the foot at the time of injury determines the fracture location and pattern (see Fig. 49.10 ). Secondary rotational or shear forces may cause increased comminution and fragment displacement with more extensive soft tissue injuries. These injuries often are comminuted and thus associated with significant soft tissue trauma, tendon entrapment or dislocation, devastation of joint architecture, and leg shortening. Due to the high-energy mechanism of injury, patients with pilon fractures frequently have other significant injuries and patient assessments should take into account these mechanisms and include a full evaluation of the neurovascular status of the foot.

One-fourth of pilon fractures are open; associated injuries include fractures of the calcaneus, tibial plateau, fibula, femoral neck, acetabulum, and lumbar vertebrae, as well as trauma to other major systems. Complications of pilon fractures are common, particularly in more severe cases. Early complications include wound infection, skin sloughing, pin site infection, and wound dehiscence. Delayed and late complications include malunion, nonunion, leg shortening, posttraumatic arthritis, avascular necrosis, and protracted pain. Some patients with severe pilon fractures ultimately require arthrodesis of the ankle joint. Careful assessment of the affected bony anatomy and neurovascular status of the foot is necessary in a pilon fracture, and in the case of open fractures, management as outlined previously should occur.

Differential Diagnoses

Differential diagnoses of pilon fractures are relatively limited since the mechanism of injury and clinical presentation makes the diagnosis fairly obvious. However, it is important not to miss other associated injuries or complications such as compartment syndrome, ankle dislocation or other skeletal injuries.

Diagnostic Testing

Plain radiographs are the initial choice of imaging for the diagnosis of pilon fractures and should include the entire tibia and fibula, as well as the ankle. CT imaging is generally required by the orthopedic surgeon for operative planning.

Management

ED treatment involves restoration of the articular surface and fibular length with reduction if necessary, combined with meticulous management of soft tissue injuries. Difficulties in achieving reduction may occur if tendon entrapment has occurred, most often the posterior medial structures. Because surgical management is required, emergent orthopedic consultation is necessary. Pilon fractures with low-grade soft tissue damage are primarily managed with ORIF. In severe pilon fractures with extensive soft tissue damage, however, results are better with a two-stage approach involving initial length restoration and external fixation, followed by anatomic reduction and internal fixation after soft tissue swelling has subsided.

Anatomy, Physiology, and Pathophysiology

Ankle dislocations are described based on the direction of displacement of the talus and foot in relation to the tibia. Dislocation may be upward, posterior, medial, lateral, posteromedial, or anterior. Medial dislocation is the most common. Most dislocations involve associated ankle fractures; rarely, however, dislocations can occur without fracture. The mechanism in all dislocations begins with axial loading of a plantar-flexed foot, which forces the talus anteriorly or posteriorly from the ankle mortise. The eventual position of the dislocation depends on the position of the foot at the time of injury and direction of the displacing force. Ankle dislocations can be closed or open and usually result from significant falls, motor vehicle collisions (MVCs), or high-speed sports. The neurovascular supply to the foot usually is intact but may be compromised in open dislocations.

Clinical Features

The diagnosis is usually obvious due to gross deformity in the ankle joint although determining the orientation of the body of the talus, which must be reduced, can be challenging without imaging. A rapid assessment of neurovascular status is necessary.

Differential Diagnoses

Due to the deformity in the ankle joint that is observed in a traumatic setting, differential diagnoses are limited to evaluation for concurrent fracture at the site of dislocation.

Diagnostic Testing

Plain radiography remains the cornerstone of diagnosis of ankle dislocation and is helpful in clarifying the orientation of the talar body prior to reduction. However, attempts at reduction should not be delayed when vascular compromise or skin tenting is present .

Management

In order to achieve talar reduction, appropriate procedural sedation or an intraarticular hematoma block is used, the patient is placed supine, and the knee is flexed to 90 degrees. Distraction of the foot, followed by a gentle force to reverse the direction of the dislocation, usually accomplishes the reduction. Difficulties in achieving reduction may be caused by entrapped posterior medial tendons. Postreduction reassessment of the neurovascular status, splint immobilization, ankle elevation, and radiography should follow. Open dislocations require the same management as previously discussed for open fractures. The prognosis for an ankle dislocation is generally good, although open fractures are associated with an increased incidence of complications. Isolated ankle dislocations once successfully reduced with documentation of intact neurovascular status, are immobilized and made nonweightbearing. These dislocations can be urgently followed by orthopedics on an outpatient basis within 48 hours.

Foundations

Ankle sprains are frequently seen in EDs and are one of the most common injuries in an active patient population. Proper diagnosis and rehabilitation are important because 40% of patients experience dysfunction for up to 6 months post injury. The term ankle sprain refers to a multitude of ligamentous and nonligamentous injuries. Even when ligamentous injury is certain, the ideal treatment approach is controversial, and there is significant variation in clinical practice.

Pathophysiology

Most ankle sprains occur from extreme inversion and plantar flexion that produce symptoms on the lateral aspect of the ankle. Usually, the anterior talofibular ligament is injured first, followed by the calcaneofibular ligament if the deforming forces are sufficiently strong (see Fig. 49.1 ). Approximately two-thirds of ankle sprains are isolated anterior talofibular ligament injuries, whereas 20% involve anterior talofibular and calcaneofibular ligament injuries. In addition, the lateral talocalcaneal ligament may be strained with an inversion injury, leading to avulsion fractures at either end of the attachment sites. Isolated calcaneofibular or posterior talofibular ligament injuries are rare.

Isolated injury of the medially located deltoid ligament occurs in less than 5% of ankle sprains and occurs during an eversion force. Rupture of this ligament usually occurs in conjunction with lateral malleolar fractures, especially when an external rotational force is involved.

Concurrent injury of the anterior talofibular and deltoid ligaments, determined by palpation and other physical signs such as ecchymosis, warrant investigation for instability of the ankle joint due to bimalleolar ligamentous injury

Injuries of the distal tibiofibular syndesmotic ligaments are uncommon in the general population because of the degree of force required but represent 10% to 20% of ankle sprain injuries in competitive athletes, the so-called “high” ankle sprain. Dorsiflexion and external rotation forces are usually responsible for this injury; their presence may significantly prolong the recovery time from concomitant lateral collateral ligament sprains.

Ligamentous injuries are classified into three grades based on functional and presumed pathologic findings, as outlined in Table 49.1 . This classification system, although commonly used, fails to characterize ankle injuries involving two or more ligaments and does not address nonligamentous injuries.

Clinical Features

An accurate history of ankle position and injury mechanism is often unavailable. Inversion followed by external rotation of the ankle suggests the potential for deltoid or syndesmotic injury. Forced dorsiflexion with “snapping” may indicate peroneal tendon displacement. On physical examination, the presence of edema, ecchymosis, and point tenderness over the medial or lateral collateral ligaments or syndesmotic ligaments suggests a ligamentous injury. Inability to bear weight in the absence of a fracture suggests the presence of a grade II or III ankle sprain. Deltoid ligament tenderness necessitates palpation of the full length of the fibula to rule out a proximal fibular fracture—type C Danis-Weber or Maisonneuve fracture (see Figs. 49.8 and 49.9 ). Tenderness should prompt imaging of the entire tibia and fibula.

Differential Diagnoses

Many injuries can masquerade as ankle sprains. Box 49.2 lists conditions to be considered with the differential diagnoses.

Diagnostic Testing

The fibular compression test, or squeeze test, can be used to diagnose fibular and syndesmotic injuries. To perform this test, the examiner places the fingers over the fibula and the thumb over the tibia at midcalf and squeezes the two bones. Pain anywhere along the length of the fibula suggests a fibular fracture or syndesmotic ligament disruption at that location. Following this, the Achilles tendon should be assessed for rupture.

Stress testing is the application of a deforming force to assess joint motion beyond the physiologic range; its presence suggests ligament disruption or mechanical instability. Common ankle stress tests include the anterior drawer test, inversion stress test, and external rotation test. The anterior drawer test primarily assesses the integrity of the anterior talofibular ligament. To perform this test, the patient is seated with the knee in 90 degrees of flexion and the ankle in a neutral position or 10 degrees of plantar flexion, which is best achieved by allowing the foot to rest along the examiner’s wrist and distal forearm, as the examiner cups the heel in his or her hand and gently flexes the ankle to the 90-degree position. The examiner then applies slow but firm traction on the heel with that hand and places the other hand on the anterior tibia to prevent the leg from moving anteriorly. Anterior displacement of the talus, the perception of a “clunk,” and the induction of a sulcus anteromedially over the joint indicate partial or complete tear of the anterior talofibular ligament.

The inversion stress test , or “talar tilt test,” evaluates the anterior talofibular ligament and calcaneofibular ligament. It is performed by inverting the heel with the knee in 90 degrees of flexion and the ankle in neutral position. Palpation of the head of the talus laterally or a finding of increased laxity compared with the uninjured side suggests partial or complete tear of these ligaments.

The external rotation stress test is indicated when injury to the distal tibiofibular syndesmotic ligaments is suspected. It is performed by externally rotating the foot with the knee in 90 degrees of flexion and the ankle in a neutral position. Pain at the syndesmosis or the sensation of lateral talar motion suggests partial or complete tear of the ligaments.

Stress testing in the ED to identify acute ligamentous disruption is often limited by pain, so to be performed properly, the joint must be anesthetized with local anesthetic. Furthermore, a positive stress test suggesting ligamentous instability rarely alters management in the ED. If needed, this test can be deferred to orthopedic follow-up.

Standard ankle radiographic views exclude fractures and detect ligamentous instability by allowing the measurement of joint spaces (see earlier discussion and Fig. 49.6 ). Stress radiographs, accomplished by taking radiographs during stress testing of the ankle, including the use of gravity stress testing, generally do not influence the emergency management of ankle sprains and we do not recommend their routine use in the ED.

The presence of avulsion fractures constitutes an important clue to the location of ligamentous injuries. Common locations for avulsion fractures include the bases of the malleoli, lateral process of the talus, lateral aspect of the calcaneus, posterior malleolus, lateral aspect of the distal tibia, and base of the fifth metatarsal.

Management

Most ligament sprains, regardless of severity, heal well and result in a satisfactory outcome. To date, compelling evidence for a significant difference in outcomes between surgical and functional (nonsurgical) treatment is lacking. Most patients with acute sprains of the ankle should start with functional treatment. For the minority who fail to respond, delayed operative repair of ruptured ligaments, sometimes years after the injury, has been shown to yield results equivalent to those with primary repair.

Functional treatment, a form of therapy in which the ankle is not fully immobilized, allowing complete or partial joint function, starts in the ED with PRICE therapy ( p rotection, r est, i ce, c ompression, and e levation). However, significant variability exists in how this combination is applied, and optimal methods for the rehabilitation of ankle sprains remain unclear. Lace-up ankle splint support is more effective in short-term edema reduction than semirigid ankle support, elastic bandaging, and taping.

For grade I or II injuries, short-term protection with a compression bandage, taping, laced-up support, or commercial brace, with the optional use of crutches for a few days, is appropriate. For patients with first-time ankle sprains, treatment with a lace-up brace combined with elastic wrapping results in an earlier return to function compared with the use of a brace alone, elastic wrap alone, or walking cast.

For severe grade II or grade III injuries, there has been equipoise regarding the merits of immobilization compared with functional rehabilitation using a removable brace, with a paucity of high-quality evidence. We recommend use of a lace-up support or air cast that permits some ankle motion. These patients should also use crutches to avoid weightbearing until they can stand and walk a few steps on the injured ankle without pain. Crutch use varies significantly, ranging from a few days to 2 or 3 weeks. Functional therapy allows for the incorporation of earlier physical therapy rehabilitation and quicker recovery.

Discharge instructions are important in ankle sprains. The expected time for return to activity is generally 2 to 4 weeks, depending on the grade of the injury, with more severe injuries taking longer; however, patients are usually able to weight bear within 7–10 days. Patients who have not returned to a normal activity level beyond this time frame should be reevaluated for talar dome osteochondral lesions, syndesmotic injury, or occult fracture with advanced imaging. Follow-up with the patient’s primary care physician or sports medicine specialist is appropriate.

Pain improves with immobilization, but additional analgesia is usually required. Appropriate pain relief can be provided by systemic nonsteroidal antiinflammatory drugs (NSAIDs), in analgesic doses, or with acetaminophen. A short course (2–3 days) of oral opioids is added when pain is severe, although this is generally not required or recommended.

Disposition

Acute ankle ligament sprains rarely require orthopedic consultation in the ED. Primary surgical repair of acute ligament rupture is controversial; possible indications include sprains with displaced osteochondral lesions, complete tears of the anterior talofibular and calcaneofibular ligaments in a young athlete, a ligament sprain associated with a fracture causing instability (e.g., a deltoid ligament rupture with a lateral malleolar fracture), and an acute severe sprain in a patient with a history of recurrent sprains. Failure of nonoperative treatment also constitutes an indication for surgical repair; however, a nonurgent referral on an outpatient basis at the discretion of the orthopedic specialist is an appropriate disposition from the ED.

Small avulsion fractures of the fibula or tibia with minimal or no displacement can be treated in the same manner as an ankle sprain. If the avulsed fragment is larger than 3 mm or significantly displaced, splinting and referral for orthopedic follow-up on a nonurgent outpatient basis within a week is justified.

Differential Diagnoses

Differential diagnoses of ankle tendon injuries is similar to that of ankle sprains and is included in Box 49.2 .

Achilles Tendon Rupture

Peroneal Tendon Dislocation or Rupture

Foundations and Clinical Features

The peroneal muscles are the primary evertors and pronators of the foot and also participate in plantar flexion. The peroneus longus and brevis tendons use the posterior peroneal sulcus (the fibular groove), located behind and underneath the lateral malleolus, as a pulley for their midfoot insertions. The peroneus brevis tendon inserts onto the tuberosity of the fifth metatarsal, and the peroneus longus tendon courses beneath the cuboid to insert onto the medial cuneiform and base of the first metatarsal. Injuries of the peroneal tendons include chronic overuse tendinopathy, tendon rupture, and tendon dislocation. The superior peroneal retinaculum ( Fig. 49.11 ), a fibrous structure running from the distal fibula to the posterolateral aspect of the calcaneus, maintains the peroneal tendons against the fibular groove and, when ruptured, causes dislocation of the peroneal tendons.

Diagnostic Testing

Plain radiographs of the ankle may show the peroneal “fleck” sign, which can be confused for a simple avulsion fracture off the lateral aspect of the lateral malleolus but represents avulsion and tibial disruption of the superior peroneal retinaculum, considered pathognomonic for a superior peroneal retinaculum tear ( Fig. 49.12 ).

Tibialis Posterior Tendon Rupture

Other Tendon Injuries

Injuries to the other tendons of the ankle are relatively rare and are outlined in Table 49.2 . The tibialis anterior tendon is the primary dorsiflexor of the foot. It courses under the superior extensor retinaculum anterior to the medial malleolus and inserts onto the navicular, medial cuneiform, and base of the first metatarsal. The flexor hallucis longus tendon is responsible for flexion of the great toe and participates in plantar flexion of the foot. It courses behind the medial malleolus through a fibro-osseous canal and travels along the undersurface of the foot to insert onto the distal phalanx of the great toe. The extensor hallucis longus tendon travels anteriorly through the superior extensor retinaculum and inserts on the dorsal surface of the base of the distal phalanx of the hallux.

Anatomy, Physiology, and Pathophysiology

The foot is composed of 28 bones and 57 articulations ( Fig. 49.13 ), which can be divided into three anatomic and functional regions—the hindfoot (talus and calcaneus), the midfoot (navicular, cuboid, and cuneiforms), and the forefoot (metatarsals, phalanges, and sesamoids). The midtarsal, or Chopart joint , connects the hindfoot to the midfoot. The tarsometatarsal, or Lisfranc joint , connects the midfoot and forefoot. The subtalar joint, comprised of three articulations between the talus and calcaneus, is another clinically important joint. Inversion and eversion of the hindfoot occur primarily through the subtalar joint, adduction and abduction of the forefoot through the midtarsal joints, and flexion and extension through the metatarsophalangeal (MTP) and interphalangeal (IP) joints.

The bones of the foot interlock to form a complex system of arches and beams tethered by ligaments and intrinsic muscles. Extrinsic muscles originating in the lower leg are responsible for most of the foot’s movements. The course and insertion of these extrinsic muscles are important in their actions and association with specific avulsions and injuries. The arterial supply to the foot is from the anterior and posterior tibial arteries as well as the peroneal artery, a proximal branch of the posterior tibial artery. Motor and sensory innervation comes from branches of the deep and superficial peroneal, posterior tibial, saphenous, and sural nerves.

Clinical Features

In the setting of foot injury, an accurate history, including the mechanism of injury, timing, and duration of symptoms is important. The location of pain, along with a description of its quality, duration, and precipitants, focuses the differential diagnoses. A history of underlying medical conditions, medications, and previous foot problems provides additional key information.

The physical examination of the foot begins, if possible, with observation of gait and proceeds with assessment of the foot in its position of rest, normally one of slight plantar flexion and inversion. Swelling, deformity, ecchymosis, open wounds, color, and temperature should be noted. Precise localization of pain or crepitus, when not precluded by swelling, is valuable and guides further diagnostic testing when indicated. The entire foot should be methodically palpated, paying particular attention to commonly injured areas. Complete assessment includes a detailed neurovascular examination.

In some situations, evaluation of active and passive range of motion is indicated. Subtalar motion is evaluated by holding the lower leg with one hand and the heel with the other. Then, with the foot in a neutral position, the heel is inverted and everted. Normal range is 5 to 20 degrees of eversion and 5 to 40 degrees of inversion although there is substantial individual variability. Midtarsal motion is evaluated by stabilizing the heel while the other hand grasps the forefoot. There should be at least 20 degrees of adduction and 10 degrees of abduction.

Forefoot motion is evaluated by flexing and extending the MTP and IP joints individually. The first MTP joint has a particularly wide passive range of motion, with 45 degrees of flexion and 70 to 90 degrees of extension. Throughout the physical examination, findings can be compared with those of the opposite uninjured foot.

Differential Diagnoses

When formulating the differential diagnoses for injuries to the foot, it is useful to categorize these by anatomic location, mechanism of injury, and chronicity of symptoms. It should be noted that because the foot is an intricate anatomic structure with several interlocking bones and complex ligamentous attachments, it is important to consider a broad differential in the assessment. There is substantial overlap of the differential diagnoses both within, and between anatomic regions. Table 49.3 outlines differential diagnoses by anatomic region.