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.
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.
TABLE 22–1Sequence of Structures Injured with Inversion and Eversion Ankle Sprains ||Download (.pdf) TABLE 22–1 Sequence of Structures Injured with Inversion and Eversion Ankle Sprains
|Inversion Stress ||Eversion Stress |
|Anterior taloﬁbular ligament |
Posterior taloﬁbular ligament
|Medial malleolus avulses (deltoid ligament rupture) |
Anterior–inferior tibioﬁbular ligament
Interosseous (syndesmotic) ligament
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
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.
TABLE 22–2Classification of Sprains ||Download (.pdf) TABLE 22–2 Classification of Sprains
|Grade ||Signs and Symptoms |
|First-degree ligament injury without tear ||Minimal functional loss (patient ambulates with minimal pain) |
Mildly tender over involved ligament
No abnormal motion or pain on stress testing
|Second-degree incomplete tear of a ligament ||Moderate functional loss (patient has pain with weight bearing and ambulation) |
Moderate swelling, ecchymosis and tenderness
Pain on normal motion
Mild instability, and moderate-to-severe pain on stress testing
|Third-degree complete tear of a ligament ||Signiﬁcant functional loss (patient is unable to bear weight or ambulate) |
Egg-shaped swelling within 2 hours of injury
May be painless with complete rupture
Positive stress test
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.
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.
Technique for performing anterior drawer stress test of the ankle.
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.
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.
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.
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.
Functional rehabilitation following an ankle sprain consists of restoring range of motion, muscle strengthening exercises, proprioceptive training, and, finally, gradual return to activity. A. Achilles tendon stretching exercises should begin within 48 hours of injury. Other range of motion exercises include knee bends with the heel on the floor (five repetitions five times a day) and alphabet exercises, in which the patient “draws” the letters of the alphabet with the toes. B, C. Strengthening exercises begin once swelling and pain are controlled. Isometric exercises (plantar flexion, dorsiflexion, inversion, and eversion) against a wall are followed by isotonic exercises. D. Proprioceptive exercises begin once full weight bearing without pain has been achieved. A “wobble board” is used for 5 to 10 minutes two times a day, first while seated, and then while standing. The patient rotates the board clockwise and counterclockwise.
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.
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.
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).
Injection of local anesthetic at the site of the sinus tarsi will relieve symptoms in patients with injury to the interosseous talocalcaneal ligament.
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
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.
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.
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
Osteochondral lesion of the talar dome. A and B. Plain film and CT demonstrating a defect of the talar dome (arrow). C and D. Another patient with a bony fragment of the talar dome visualzed (arrow).
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
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.
The mechanism by which a talotibial exostosis forms.
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).
Dislocation of the peroneal tendon caused by rupture of the retinaculum is shown.
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
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.
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
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.
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.
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).
Isolated left ankle dislocation without fracture. A. Clinical photograph. B. Radiograph.
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.