Chapter 276: Ankle Injuries

Given the mobility of the ankle joint and our bipedal existence, ankle injuries are a common complaint. They represent 14.6% of all visits to the ED.¹ Fractures of the lateral malleolus are more prevalent in men younger than 50 years old and in women older than 50 years old.^2,3 Previous ankle sprain and participation in sports like soccer, basketball, rugby, and football are risk factors for ankle injuries.^4,5,6,7 A review of the National Electronic Injury Surveillance System in 2009 reported an incidence of ankle sprains of 206 per 100,000 people in the United States.⁸

The proximal part of the ankle mortise is comprised of the distal fibula and tibia that fits on top of the talus. These bones are wider anteriorly than posteriorly. Joint stability is provided by medial and lateral malleoli extending on either side of the talus. The medial deltoid ligament, lateral ligament complex, and syndesmosis are the three distinct groups of ligaments that stabilize the ankle⁹ (Figure 276-1). The deltoid ligament is the strongest of these ligaments and is a thick, triangular band of tissue originating from the medial malleolus. The lateral ligament complex consists of the lateral malleolus that attaches to the anterior and posterior aspects of the talus and calcaneus by the anterior talofibular, posterior talofibular, and calcaneofibular ligaments, respectively. This ligament complex, the anterior talofibular ligament in particular, is the weakest and most commonly injured in lateral sprains and represents 85% of all ankle sprains.¹⁰ The syndesmosis, which holds the tibia and fibula together, is a group of four distinct ligaments attaching the distal tibia to the fibula just above the talus (Figure 276-1). The syndesmosis allows the fibula to rotate and carries approximately 16% of the axial load.⁹

The ankle is considered a hinged joint, but ligamentous attachments allow for some rotation and translation within the mortise of the talar dome.⁹ Branches of the sciatic nerve, the superficial peroneal, deep peroneal, peroneal, and tibial, innervate the four muscle groups of the ankle joint with branches of the popliteal artery serving as the blood supply (Figure 276-2). The tibialis anterior, extensor digitorum longus, and extensor hallucis longus muscles run over the anterior aspect of the joint and are responsible for dorsiflexion. Inversion is accomplished by the tibialis posterior, flexor digitorum longus, and flexor hallucis longus. The peroneus longus and brevis muscles, sharing a common synovial sheath held in place by a groove on the posterior aspect of the lateral malleolus and superior retinaculum, run laterally to evert and plantarflex the joint. Plantarflexion is primarily accomplished by the gastrocnemius and soleus muscles.

HISTORY

Understanding the mechanism and timing of the injury is important. Document these details along with any previous bony or soft tissue injuries. Patients with signs of neurovascular compromise, including coldness and numbness of the foot, a rapid onset of swelling, extreme pain, and complicating conditions such as diabetes, require urgent evaluation.⁵ A normal-appearing ankle does not preclude the need for further inquiry. Due to the significant swelling typically present after acute injuries, examining the ankle is challenging but can be helped by elevation of the injured extremity and ice applied at triage. Peroneal spasms may mask any instability in the joint.⁹

PHYSICAL EXAMINATION

Place the patient on a stretcher to perform a thorough evaluation. A systemic approach to the examination decreases the chance of missed injuries. Starting with the skin and soft tissues, note any ecchymosis, abrasions, or swelling. Note the position, swelling, and skin integrity of the joint as well as any areas of tenderness or crepitus. Joints above and below the ankle need to be examined for any concomitant injuries. Suspect a Maisonneuve fracture (or fibulotibialis ligament tear) if there is tenderness of the fibular head or proximal fibular shaft. Palpate the area of obvious injury last. Test the functionality of the joint with both active and passive plantarflexion, dorsiflexion, and full range-of-motion exercises. Peroneal tendon injuries can occur from forced dorsiflexion, which presents as weakness on eversion (Figure 276-3). Check stability in external rotation, varus, and valgus. Palpate the posterior aspects of the lateral and medial malleoli, starting proximally to the joint and working distally. If there is a concern for isolated fibular fractures, check for evidence of injury to the syndesmosis or deltoid ligament.⁹ A positive anterior drawer test (Figure 276-4) is indicative of a torn anterior talofibular ligament. A positive anterior drawer test, swelling, and a hematoma are signs of a grade III sprain. Syndesmosis injuries can be deceiving because the patient describes ankle pain, but there is typically little ankle edema or ecchymosis. The crossed-leg test (compressing the fibula toward the tibia just above the midpoint of the calf¹¹) can detect a syndesmosis injury and is indicated if pressure to the medial aspect of the knee elicits pain in the syndesmosis (Figure 276-5). The squeeze test is performed by squeezing the calf just above the ankle joint. Pain indicates syndesmosis injury. Calcaneofibular ligament instability can be detected with the inversion stress test or talar tilt.⁶ If the examination is uncomforTable for the patient, consider a hematoma block, sedation, or both to perform a more thorough examination.¹¹

Examine areas in close proximity to the ankle as well. What may be described as an ankle injury may end up being an injury to the Achilles tendon or foot and cannot be excluded by ankle radiographic imaging. Assess the integrity of the Achilles tendon. Fluoroquinolones and corticosteroids increase the risk of such an injury.¹² Perform the Thompson test (see Figure 44-4 in chapter titled "Leg and Foot Lacerations") if there is tenderness or a defect. Place the patient prone on the stretcher and squeeze the calf. Loss of plantarflexion indicates a complete Achilles tendon rupture. Palpate the hindfoot and midfoot over the calcaneus, tarsals, and base of the fifth metatarsal to check for areas of tenderness that may require further investigation.

Perform a neurovascular examination. Check dorsalis pedis and posterior tibial pulses and document digital capillary refill. Inability to dorsiflex the toes suggests a tibial nerve injury. Inability to plantarflex the great toe is suspicious for peroneal nerve injury.

If there are any significantly displaced fractures or dislocations, immobilize the joint in a neutral position with a well-padded splint to reduce further soft tissue injury. Follow this with elevation and application of ice to reduce edema. Emergently reduce any displaced fractures or dislocations with neurovascular compromise (see later treatment section under "Dislocations").

IMAGING

The Ottawa Ankle Rules for Ankle and Midfoot Injuries^{2,13,14,15,16,17} are easily applied by physicians and triage nurses.^18,19 The rules are summarized in Figure 276-6.

The rules were originally developed for patients older than age 18 years who were able to cooperate, were not intoxicated, and had no distracting injuries or decreased sensation. Assuming the patient does not have any bony tenderness, assess the ability to bear weight by having the patient take four steps, resulting in two transfers to and from the injured ankle. The initial studies demonstrated a 30% reduction for the need of ankle radiographs.^16,20

The standard ankle trauma series consists of three views: anteroposterior, 15-degree internal oblique, and lateral views. See Figure 276-7 for normal anatomy. About 95% of all ankle fractures can be detected with any two of these views.⁹

When there is an abnormal motion of the talus within the mortis, there is stress on the malleoli and ligaments, which causes the injury. Fractures above the talus and those that cause disruption of both sides of the joint have the potential to create an unsTable injury. Instability of the joint is usually diagnosed based on plain radiographs because pain and swelling make it difficult to determine true stability of an acutely injured ankle. If radiographs are normal but there is concern about stability, weight-bearing ankle films can be helpful. US can detect Achilles tendon injuries²¹ and ankle fractures.²²

CT and MRI may play a role in better delineating pathology. Ideal imaging for a CT includes both axial and direct coronal images with sagittal reformations. To obtain these images, keep the ankle between neutral and 20 degrees of plantarflexion when possible, similar to that for plain radiographs. CT can be used for operative planning by orthopedic surgeons and to evaluate comminuted fractures and complex bony injuries like pilon fractures and malunions.⁷ MRI can help define soft tissue, muscle, ligamentous, and tendon injuries and is used more in the outpatient setting for subacute and chronic pain presentations.^9,23

CLINICAL FEATURES

A peroneal tendon subluxation and dislocation occurs when there is a sudden hyperdorsiflexion of the foot in a position of eversion, as in skiing. The superior retinaculum, which holds the peroneal tendons in place, is torn from the posterolateral malleolus. This leads to a small avulsion fracture in more severe injuries with a dislocation or anterior subluxation of the peroneal tendon over the tip of the fibula. Consider this injury when there is ecchymosis or tenderness over the posterior edge of the lateral malleolus and no tenderness over the talofibular ligament.

Achilles tendon ruptures happen with sudden plantarflexion of the foot. A complete tendon rupture will become apparent with palpation of a defect over the Achilles tendon and is identified by the Thompson test (Figure 276-8). US can also identify Achilles tendon ruptures (Figure 276-9).

TREATMENT

The treatment for both types of tendon rupture is often operative repair, especially for those who wish to return to full activity.

CLINICAL FEATURES

The most common type of ankle sprains is one to the lateral ankle. Typically, these are minor and are due to an inversion injury when the ankle is plantarflexed. Sprains are categorized into three grades. Grade I involves no tearing of the ligaments with minimal functional loss, pain, swelling, and ecchymosis. Weight bearing is tolerable. Grade II sprains occur with a partial tear and some loss of functional ability. Grade II sprains tend to be more painful, with swelling, ecchymosis, and difficulty bearing weight. Grade III sprains result from a complete tear, with significant functional loss, pain, swelling, and bruising, and almost a universal inability to bear weight.⁶ It has been argued, however, that assigning a grade to the sprain is less important than the stability of the joint.²⁴ Joint stability is the primary determinant of a treatment plan for a sprain.

An isolated sprain of the medial deltoid ligament is rare. Medial deltoid ligament tears are usually associated with a fibular fracture or tear of the tibial-fibular syndesmosis from an eversion injury. If there is significant medial malleolus tenderness and swelling, suspect a Maisonneuve fracture of the proximal fibula and fibular shaft. Negative radiographs should suggest syndesmosis tears.

Injuries to the tibiofibular syndesmotic complex are associated with hyperdorsiflexion injuries when the talus moves superiorly and separates the tibia and fibula. This leads to a partial or complete tear of the syndesmosis with complaints of pain just above the talus.

If there is concern for an unsTable ligamentous injury, weight-bearing views of the ankle can help diagnosis—an unsTable ligamentous injury may demonstrate talar shift.

TREATMENT

The immediate goals are to decrease pain and swelling and protect ligaments from further injury. The PRICE protocol (protection, rest, ice, compression, elevation) involves elevating the ankle and protecting it with a compressive device along with applying ice and resting up to 72 hours to allow the ligaments to heal.⁶ There is controversy as to whether or not early immobilization versus functional treatment results in the best outcomes. There is a trend toward favoring early functional treatment over immobilization.⁷ Patients returned to mobility anywhere between 4.6 and 7.1 days sooner with functional treatment when compared with immobilization.²⁵ Functional treatment usually consists of three phases: (1) PRICE protocol within the first 24 hours of injury; (2) motion and strength exercises to begin within 48 to 72 hours; and (3) endurance training, focused toward specific sports when applicable, and training to improve balance after the second phase begins.⁶

In patients with a lateral ligament sprain, a sTable joint, and the ability to bear weight, treatment consists of analgesics, an elastic bandage or ankle brace, and no sports involvement, with follow-up in a week if no improvement. Lace-up supports may reduce persistent swelling when compared to elastic bandages or rigid ankle supports.²⁶ For patients who are unable to bear weight but have a sTable joint, provide an ankle brace and crutches and have them follow-up with either their primary care provider or orthopedic surgeon within 1 week for repeat evaluation. Given the trend for early immobilization, functional braces, such as semirigid (e.g., Aircast) and soft, lace-up braces, are commonly used. There is no consensus as to which leads to a more favorable outcome,²⁷ although early rehabilitation of low-grade ankle sprains results in a good outcome.²⁸ Another option is an inflaTable cast boot (also called walking fracture boot or air cast boot) that molds to the foot with inflaTable air bladders. This device can also be used for sTable ankle fractures.

Treat medial ligament sprains with PRICE and early referral to an orthopedic surgeon given the risk for undetected underlying fractures. Consider early orthopedic referral for syndesmotic complex sprains given the expected prolonged recovery time.

Refer patients with an unsTable joint to an orthopedic surgeon after placement of a posterior splint for stabilization. Establish contact with the orthopedic surgeon early because the timing of treatment and follow-up is ultimately at his or her discretion.

There is no consensus as to whether surgery versus conservative treatment results in more favorable outcomes.²⁹ Cryotherapy with ice will help decrease pain and limit swelling and should be applied directly to the ankle or splint but not left on for >20 minutes at a time. Therapeutic ultrasonography is not helpful.⁵

CLINICAL FEATURES

Most ankle dislocations are associated with a fracture and can occur in one of four planes. Posterior dislocations are the most common and occur with a backward force on the plantarflexed foot, usually resulting in rupture of the tibiofibular ligaments or a lateral malleolus fracture. The less common anterior dislocation results from a force on the dorsiflexed foot with an associated anterior tibial fracture. A lateral dislocation results in ligamentous disruption and fracture of one or both malleoli (Figure 276-10). An axial compression force can drive the talus upward with an associated fracture of the talar dome and disruption of the syndesmosis.

TREATMENT

There is a significant concern for neurovascular compromise. Check carefully for an open fracture in these instances. If the patient has intact pulses, dislocations associated with fractures should be reduced by an orthopedic surgeon. If vascular compromise is present, as evidenced by a dusky foot or absent pulses, or there is tenting of the skin, an immediate reduction by the emergency physician is warranted without any pre-reduction radiographs.

First provide appropriate sedation and analgesia before attempts at reduction. Grasp the heel and foot with both hands, and gently apply traction and rotation opposite to the direction of the mechanism of injury. Confirm pulses and distal perfusion, and then apply a splint and elevate the foot while waiting for orthopedic evaluation. Confirm and document distal perfusion again after splint application. Any dislocations that cannot be reduced using closed techniques will require open reduction.

CLINICAL FEATURES

Strains are injuries to muscle or tendons not usually associated with a specific injury but due to repetitive stress and overuse. Common muscles and tendons involved include the extensor digitorum longus, extensor hallucis longus, peroneus brevis and longus, and anterior tibial tendon (Figure 276-11). Strains can be due to athletics or poorly fitting footwear. Contusions are usually caused by direct trauma from a projectile like a baseball or hockey puck. Fractures associated with contusions are rare and usually involve only the bony cortex.

TREATMENT

For overuse injuries, analgesics, especially nonsteroidal anti-inflammatory drugs, will help, along with rest and cessation of the activities that are causing the strain. Targeted exercises may help in the recovery as well. Contusions are treated symptomatically with analgesia and ice.

CLINICAL FEATURES

Radiographically, ankle fractures are described as unimalleolar, bimalleolar (Figure 276-12), and trimalleolar (Figure 276-13). A bimalleolar fracture is fracture of the lateral and medial malleoli; trimalleolar fracture additionally involves the posterior malleolus.

The ankle consists of a ring of bone and ligaments around the talus. The ring is composed of the tibia, tibiofibular ligament, fibula, lateral and medial ankle ligaments, and calcaneus.³⁰ A single ring disruption is typically a sTable injury. Injuries involving two or more components of the ring are unsTable injuries and usually need surgical fixation.

The Danis-Weber and Lauge-Hansen schemes are used by orthopedic surgeons to classify ankle fractures and help determine surgical repair. The Danis-Weber system classifies fracture patterns based on the level of the fracture of the fibula.^31,32,33 The Lauge-Hansen system classifies fractures based on the position of the foot at the time of injury.³⁴

Critical aspects of the examination for ankle fractures are summarized in Table 276-1.

TREATMENT

The goal is to restore the anatomic relationship of the ankle, maintain reduction during the healing, and mobilize the ankle early. Treat small fibular avulsion fractures as sTable ankle sprains (see earlier section, "Ligament Injuries") if they are minimally displaced (<3 mm in diameter) and there is no sign of medial ligament injury.

Most other ankle fractures require immobilization by either cast alone or surgical repair and casting.^35,36 Severe comminuted fractures are at risk for compartment syndrome, fat emboli, and poor healing. Urgent orthopedic consultations in the ED is necessary. Until definitive fracture treatment can be provided, apply a posterior splint and keep the patient non–weight bearing (see Figure 267-15 in chapter 267, "Initial Evaluation and Management of Orthopedic Injuries, Posterior Ankle Mold). Provide analgesics, and remind the patient to elevate the leg and apply ice. Table 276-2 provides guidelines for orthopedic consultation and follow-up.

The most important prognostic factor in open ankle fractures is the amount of energy involved in the injury and amount of soft tissue damage involved. Open fractures require rapid surgical management that involves aggressive debridement of nonviable tissue and either internal or external fixation.⁹ Administer empiric antibiotics, most commonly IV cefazolin, and add an aminoglycoside for contaminated wounds. Use clindamycin in patients with a penicillin allergy. Update the tetanus status of the patient as needed.

While waiting for the orthopedic surgeon, irrigate the wound with several liters of normal saline, then apply sterile gauze soaked in saline over the open wound, and secure it in place with a gauze roll. Do not use iodine solutions, as they are caustic to tissues. Splint the injury to stabilize it while obtaining radiographs and coordinating orthopedic care.

To date, there is no established standard of care regarding the time of orthopedic consultation and follow-up. Whether or not an orthopedic surgeon sees the patient in the ED depends on the specialist resources available. Table 276-2 can serve as a general guideline for local practice standards and resources. Most severe fractures require orthopedic consultation in the ED.

Acknowledgments: The authors would like to thank Drs. John A. Michael and Ian G. Stiell for their contributions to previous editions of this chapter. We would also like to thank Drs. Esther Choo and Robert DeMayo for the radiology images.