Ligaments of the Ankle

The medial side of the ankle is supported by the deltoid ligament (Fig. 85.2). The deltoid ligament has five components: one deep and four superficial. The deep ligament attaches to the tibia and the undersurface of the talus. The superficial ligaments are the tibionavicular, anterior talotibial, calcaneotibial, and posterior talotibial.

Fig. 85.2 Medial ligaments of the ankle.

The lateral aspect of the ankle has three supporting ligaments: the anterior talofibular, calcaneofibular, and posterior talofibular (Fig. 85.3). The tibiofibular ligaments include the anterior and posterior inferior ligaments, which bind the distal ends of the tibia and fibula, and the superior ligaments of the same name, which bind the tibia and fibula at the proximal articulation. Other supporting structures are the inferior transverse ligament and the interosseous ligament. The latter is not part of the ankle but nevertheless provides a strong bond between the tibia and fibula.^2,3

Fig. 85.3 Lateral ligaments of the ankle.

Subluxation of the Peroneal Tendons

The peroneus longus and brevis tendons lie in a shallow groove immediately posterior to the distal end of the fibula. Rupture of the superior peroneal retinaculum results in subluxation or dislocation of the peroneal tendons. This injury is often mistaken for a common sprain in the emergency department (ED). However, it differs in that the pain and swelling are located along the posterior border of the lateral malleolus. It results from forced dorsiflexion with reflex contraction of the peroneal muscles. Patients complain of pain and a snapping sensation over the posterolateral aspect of the ankle with weakness of eversion.⁶

During physical examination, pain is elicited on palpation of the area, and swelling is also noted. The subluxation can be reproduced with dorsiflexion and eversion of the foot.

Do not mistake subluxation of the peroneal tendons for an ankle sprain because the treatment and prognosis are different.

Treatment is directed at stabilization of the subluxed tendon. A U-shaped felt pad is placed over the lateral aspect of the ankle with the tip of the fibula lying inside the “U.” The ankle is then taped to ensure that the U-shaped pad stays in place. Refer to an orthopedic surgeon for further evaluation in the event that corrective surgery is warranted.

Achilles Tendon Injuries

The most common conditions affecting the Achilles tendon in patients seen in the ED range from tendonitis to rupture. Rupture of the Achilles tendon is missed in more than 20% of patients with this injury. The rupture may be partial or complete. Occasionally, because of significant swelling and a hematoma over the area, a discernible defect in the tendon may be difficult to identify.

The history usually includes some form of violent motion around the ankle; the injury is often seen in basketball and tennis players. Weekend athletes in their third or fourth decade are most commonly affected.

Physical examination reveals swelling and tenderness, as well as a partial or complete defect in the tendon. A positive Thompson test is diagnostic. It is performed by having the patient lie prone on a gurney or stand with the knee of the affected leg resting on a chair (Fig. 85.6). The examiner then squeezes the calf muscles. Individuals with normal Achilles tendons will plantar flex as the maneuver is performed.³

Fig. 85.6 Thompson test.

Note that the Thompson test can be misleading, especially with partial tears, because the accessory ankle flexors are often squeezed together with the contents of the superficial leg compartment.

Treatment consists of either a compression wrap or a short leg plaster splint with the foot positioned in equinus (plantar flexion). Crutches, non–weight bearing, and analgesics are also indicated. Prompt orthopedic consultation to determine the necessity for surgical repair is advised.

Danis-Weber Classification System

This classification system has four injury patterns: (1) supination adduction (SA or Weber A), (2) supination external rotation (SE or Weber B), (3) pronation abduction (PA or Weber C1), and (4) pronation external rotation (PE or Weber C2). The names of these injury patterns can be thought of in simple terms as indicating the initial position of the foot (supination or pronation) and the direction of the injuring force acting through the talus (adduction, abduction, external rotation). The location and type of fibula fracture are the key to understanding the classification.²

Supination Adduction (SA, Weber A)

Supination (inversion) of the foot and application of an adducting force on the talus result in two sequential injuries: transverse fracture of the lateral malleolus below or up to the level of the tibiofibular joint and a ligament tear (SA I). As the force progresses, the talus impacts the medial malleolus and causes an oblique medial malleolar fracture (SA II) (Fig. 85.8).

Fig. 85.8 Supination adduction (SA, Weber A).

Supination External Rotation (SE, Weber B)

This is the most common mechanism of a “twisted ankle” injury. Supination of the foot and application of an external rotation force on the talus result in up to four sequential injuries (Fig. 85-9): tear of the anterior inferior tibiofibular ligament (SE I); short oblique fracture of the fibula (SE II), which is best seen on a lateral radiograph; fracture of the posterior malleolus (SE III); and transverse fracture of the medial malleolus (SE IV) or a tear of the deltoid ligament (or both).

Fig. 85.9 Supination external rotation (SE, Weber B).

Pronation Abduction (PA, Weber C1)

In this injury, pronation (eversion) of the foot and application of an abducting force on the talus result in up to three sequential injuries (Fig. 85.10). First, a transverse fracture of the medial malleolus occurs (PA I), and then as the forces progress, the anterior inferior tibiofibular ligament tears (PA II). Finally, further abduction of the talus results in an oblique fracture of the distal end of the fibula (PA III). This fibula fracture ends just above the level of the joint line and is best seen on an anteroposterior (AP) or mortise view.

Fig. 85.10 Pronation (eversion) of the foot and application of an abducting force on the talus can result in up to three sequential injuries.

Pronation External Rotation (PE, Weber C2)

In pronation external rotation, pronation (eversion) of the foot and application of an external rotation force through the talus result in up to four sequential injuries (Fig. 85.11). Similar to the pronation abduction mechanism, the first two injuries are the same: transverse fracture of the medial malleolus (PE I), followed by a tear of the anterior inferior tibiofibular ligament (PE II). The third injury is a short spiral or oblique fracture, usually 6 to 8 cm above the syndesmosis but possibly as high as the midshaft level (PE III). The fourth injury is fracture of the posterior malleolus (PE IV).

Fig. 85.11 Pronation external rotation (PE, Weber C2).

Pronation (eversion) of the foot and application of an external rotation force through the talus can result in up to four sequential injuries.

Maisonneuve Fracture (Weber C3)

The exact mechanism leading to a Maisonneuve fracture is not clear. It appears to combine different forces and possibly shifting foot positions. Patients have isolated medial ankle tenderness and swelling. On further examination, tenderness at the level of the proximal end of the fibula is also identified. This fracture is unstable and warrants clinical and radiographic evaluation of the entire lower extremity below the knee. It often goes unrecognized and is identified merely as “just another ankle sprain.” Therefore, vigilance must be exercised when a medial ankle injury is identified in any patient. These medial ankle injuries could be limited to the deltoid ligament, an isolated fracture of the posterior tibial tubercle, or a medial malleolar fracture in the absence of a lateral malleolar fracture. The classic appearance of the injury is a fracture of the neck of the fibula—either linear or comminuted (Fig. 85.12). Emergency orthopedic consultation is necessary.⁴

Fig. 85.12 Maisonneuve fracture.

Salter-Harris Classification System

The Salter-Harris classification system describes injuries that occur only around growth plates. Hence, just children have Salter-Harris fractures.

Injuries to the ankle in the pediatric population generally occur at the level of the bone physis. The Salter-Harris classification system enables definition of the type and severity of the fracture. Salter-Harris fractures are generally broken down into five categories as shown in Figure 85.13 and Table 85.2.⁵

Fig. 85.13 Salter-Harris fractures are generally broken down into five categories.

Triplane Fractures

This type of fracture is generally seen in older children with partially closed epiphyses and resembles a Salter-Harris type IV fracture. The mechanism is usually external rotation. Even with proper care and reduction, this fracture can result in epiphyseal growth arrest and deformity. If unsure of the fracture lines on plain film radiographs, computed tomography (CT) is recommended to ascertain the position of the fracture fragments (Fig. 85.14).

Fig. 85.14 Triplane fracture.

Treatment consists of reduction and immobilization in a long leg cast for 4 weeks followed by a short leg cast for an additional 2 weeks. Displaced fractures that cannot be easily or anatomically reduced will require open reduction and internal fixation.

Talar Fractures

Injuries to the talus result from high-energy trauma such as falls from heights or motor vehicle accidents. These injuries may occur at the neck or the body of the talus. Avascular necrosis is common when the injury involves the neck of the talus because of the limited blood supply to this area of the bone. Most of these injuries are significant and all warrant orthopedic consultation. For complete classification details, see Fracture and dislocation compendium. Orthopaedic Trauma Association Committee for Coding and Classification. J Orthop Trauma 1996;10(Suppl 1):104-8.

Osteochondritis Dissecans (Osteochondral Fracture)

These fractures result from a mechanism similar to that of ankle sprains. When the ankle is forcibly inverted while in plantar flexion or dorsiflexion, the dome of the talus is compressed against the fibula or the tibial plafond. This results in several degrees or “stages” of lesions (Fig. 85.15). More often than not, the initial radiographs are negative, and diagnosis will require CT or MRI. The diagnosis is missed in 40% to 50% of patients seen in the ED with an ankle injury. Therefore, a high index of suspicion is warranted with these injuries, especially if the patient has experienced reinjury, chronic swelling, or locking of the ankle 4 to 5 weeks after the injury.²

Fig. 85.15 Osteochondritis dissecans (osteochondral fracture).

Calcaneal Injuries

The calcaneus is the most frequently fractured tarsal bone and accounts for more than 60% of tarsal fractures. These fractures are frequently work-related injuries in roofers or other individuals working at heights. The majority are intraarticular, with the remainder being classified as extraarticular.

The most common extraarticular fracture is a calcaneal body fracture. In decreasing frequency, other locations of calcaneal fractures are at the anterior process, the superior tuberosity, and the area of the sustentaculum tali; isolated injuries are rarely seen at these sites. Calcaneal fractures are infrequently encountered as open fractures. Open injuries are reported to occur in only 2% of cases. As a result of the accompanying mechanisms and forces related to calcaneal fractures, other pathology such as spinal injuries and extremity fractures are usually associated with injuries to the os calcis. Multiple complications such as gait abnormalities, arthritis, and leg length discrepancy are generally the sequelae of calcaneal fractures.⁸

Plain films, including AP, lateral, and axial views of the hindfoot, provide a good initial assessment. CT is generally used to ascertain the true extent of these complex fractures.

One method of assessing the integrity of the calcaneus is measurement of the Böhler angle. This angle is normally 30 to 35 degrees and is determined by tracing two lines on a lateral view of a radiograph of the foot (Fig. 85.16). One line is drawn from the posterior tuberosity to the apex of the posterior facet. A second line connects the apex of the posterior facet to the anterior (beak) process. An angle of 20 degrees or less should raise suspicion for a compression fracture of the calcaneus.³

Fig. 85.16 Critical angles for evaluating calcaneal fractures.

Another less frequently used angle measurement is the crucial angle of Gissane. This angle is formed by the downward portion of the posterior facet where it connects to the upward portion. This angle normally measures 100 degrees.³

Other Tarsal Conditions

Avascular necrosis occurs in many areas of the skeleton. The foot is not spared, with the tarsal navicular experiencing the greatest frequency of this condition. Stress fractures can result in avascular necrosis when they go unrecognized and untreated.⁸ Examples of these injuries, with a description of the clinical findings, diagnosis, and treatment, appear in Table 85.3.

Lisfranc Injury

A Lisfranc injury is uncommon and generally associated with significant force. Physical examination reveals significant swelling and tenderness of the midfoot area commensurate with the magnitude of the injury. On occasion, ecchymoses of the midarch area of the foot are present and are diagnostic of this injury. The vasculature should be scrutinized carefully, especially if the intercommunicating arterial branch between the dorsalis pedis artery and the plantar arterial arch has been disrupted. It can lead to a compartment syndrome, which requires prompt intervention by an orthopedic surgeon.⁸

Metatarsal Injuries

Metatarsal Fractures

Three types of fractures commonly occur in the proximal fifth metatarsal (proximal to distal): tuberosity avulsion fracture, Jones fracture, and proximal diaphysial stress fracture. Each has distinct characteristics, and the approach to treatment is often controversial. Nevertheless, most of these fractures heal with immobilization over a period of 3 to 8 weeks, depending on location. Treatment of displaced intraarticular fractures, delayed union, and nonunion usually requires operative methods. A Jones fracture has a high rate of nonunion and may require surgical intervention. Patients must be warned of this potential problem. Tuberosity fractures and Jones fractures must not be confused despite their proximity on the fifth metatarsal (Fig. 85.17).^3,9

Fig. 85.17 Metatarsal fracture.

Sesamoid Bone Fractures

The foot has many sesamoid bones. However, those most commonly injured are in the area of the great toe and occasionally in the os trigonum located posterior to the posterior tubercle of the talus. These fractures are infrequent and often go unrecognized. They can occur as a result of direct and indirect trauma. Direct traumatic injuries result from crush-type mechanisms such as falling from a height or direct impact with an external object. Indirectly, the great toe suffers a hyperdorsiflexion-type injury that results in the fracture. In the case of the os trigonum, plantar flexion is the mechanism. Ballet dancers suffering from these injuries may at some time require removal of the bone because of chronic pain.³

Examination reveals localized tenderness over the sesamoid and reproducible pain on dorsiflexion of the great toe. In the case of the os trigonum, physical examination almost always reveals tenderness anterior to the Achilles tendon and posterior to the tibia, as well as decreased plantar flexion. Pain is reproduced by plantar flexion or resisted plantar flexion of the great toe.

Radiographically, sesamoid fractures appear to have irregular margins, as opposed to the smooth contours of a bipartite sesamoid bone. Nonunion is frequent because of their poor vascular supply. This can result in chronic pain and swelling, as well as disability. It is therefore important to stress the need for orthopedic follow-up.

Treatment is directed at protection and immobilization of the affected area in either a walking cast or boot for 4 to 6 weeks.³

Toe Fractures

Toe fractures are generally the result of direct trauma such as a heavy object falling on the foot. Occasionally, walking or kicking an immobile object will result in a displaced fracture. The eponym “nightwalker” fractures has been given to injuries that occur at night while navigating in a dark room.

Treatment is directed at anatomic integrity and immobilization. Therefore, reduction of displaced fractures with “buddy tape” immobilization is the standard. All other fractures that are not displaced warrant immobilization in the same fashion; a hard-soled cast shoe is recommended until the pain resolves, at which time an athletic shoe can be worn. In the event of a large intraarticular fracture fragment or significant displacement of the fragments, emergency orthopedic consultation is required.⁸

Plantar Fasciitis

Plantar fasciitis is a fairly common condition in runners and long-distance walkers. It can have an acute cause from sudden excessive loading of the foot; more commonly, however, it becomes symptomatic in a gradual manner from excessive pronation of the foot. These chronic insults result in microtears of the plantar fascia.

Individuals with a high-arched foot are more prone to this injury. The patient reports pain in the plantar area of the foot, especially in the morning. Occasionally, the pain can be sharp and lancinating and resemble neuropathic pain.

Physical examination reveals tenderness along the plantar area of the hindfoot, near the origin of the plantar fascia. Swelling may be noted occasionally, as well as reproduction of the pain with dorsiflexion of the foot.

Treatment consists of ice massage and gentle stretching of the fascia. The latter is accomplished by stretching of the Achilles tendon, as well by rolling the foot back and forth over an object such as a can of soup. An orthotic device is helpful for individuals with excessive pronation on ambulation. Physical therapy in the form of massage and ultrasonography is sometimes necessary. Steroid injections can occasionally be used but should be done judiciously.⁵

Tarsal Tunnel Syndrome

Compression of the posterior tibial nerve as it courses through the tarsal tunnel is known as tarsal tunnel syndrome. The tarsal canal is covered by the flexor retinaculum, which extends posteriorly and distally to the medial malleolus. The floor is formed by the calcaneus, tibia, and talus. Tendons of the flexor hallucis longus, flexor digitorum longus, and tibialis posterior muscles, the posterior tibial nerve, and the posterior tibial artery and vein pass through the tarsal tunnel.

Patients complain of shooting or radiating pain to the forefoot or the plantar arch. Numbness or a burning or tingling sensation may also be present in the ankle, heel, arch, or toes. Activity will often aggravate the symptoms.

Shooting pain distally may be elicited when the entrapped nerve is percussed (Tinel sign). Nerve conduction velocity studies are helpful in obtaining a definitive diagnosis. The multiple causes of tarsal tunnel syndrome are listed in Box 85.3.

Several treatment options are available, depending on the cause. Conservatively, the area can be put at rest with the use of night splints. Orthotics can be used to correct hyperpronation of the foot. Women should stop wearing high-heeled shoes.

NSAIDs and occasionally physical therapy may be of benefit. Steroid injections may also be of some help. Ultimately, tarsal tunnel release can be performed to alleviate the condition.

Ottawa Ankle Rules

In an effort to decrease the number of ankle radiographs used in the diagnosis of acute ankle injuries, Stiell et al. from the Ottawa Civic and the Ottawa General Hospitals in Canada conducted a prospective study that included more than 750 patients seen in the ED with acute blunt ankle injuries. They determined that ankle films were necessary only when patients with pain near the malleoli exhibited one or more of the findings shown in Box 85.4.

Likewise, for injuries to the foot, radiographs would be necessary only with pain in the midfoot area and with bone tenderness at the navicular, the cuboid, or the base of the fifth metatarsal.¹¹