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Ankle Sprains

The ankle joint connects the foot to the leg. It is made up of three bones: the lower tibia, the lower fibula, and the talus. Other names for the ankle joint include the "tibiotalar joint" and the "talocrural joint."

ankle_front

The bones of the ankle as seen from the front

ankle_side

The bones of the ankle as seen from the side

The bones of the ankle are primarily held together by strong structures called ligaments. An injury to a ligament is called a "sprain." A sprain can range from a partial tear to a complete tear of a ligament.

ankle ligaments

Figure 3 – Ankle Ligaments

Sprains are common injuries. In fact, ankle sprains are one of the most common orthopedic injuries overall, accounting for upward of 40% of all athletic injuries. By some estimates, more than 20,000 ankle sprains occur each day in the United States.

There are three sets of ligaments that hold the ankle together (figure 3), and each can be injured. The most frequently injured ligaments in the ankle are those located on the outer, or lateral, side of the ankle. When this lateral ligament complex is injured, a patient is said to have sustained a lateral ankle sprain. These injuries account for more than 85% of all ankle sprains.

Lateral Ligament Complex

Less commonly, those ligaments that hold the lower tibia and fibula together, known collectively as the "distal lower extremity syndesmosis" (DLES, figure 4), may also be torn. These injuries are referred to as high ankle sprains and by some estimates account for 10% of ankle sprains. High ankle sprains are caused by forceful external rotation of the foot, where the foot is rotated outward in the direction of the small toe.

distal lower extremity syndesmosis (DLES)

Figure 4 – distal lower extremity syndesmosis (DLES)

The "syndesdmostic" ligaments that hold the tibia and fibula bones together are located higher than the lateral ankle ligaments (hence the phrase "high" ankle sprain).

Finally, the deltoid ligament (link to http://www.bartleby.com/107/illus354) on the inner, or medial, side of the ankle may be injured. These injuries are referred to as medial ankle sprains and produce pain on the inner, or medial, side of the ankle. Medial ankle sprains rarely occur in the absence of a simultaneous ankle fracture or other ankle sprain. To this end, isolated injuries of this ligament probably account for less than 1 % of all ankle sprains.

As noted, ankle sprains are common. However, one must be careful not assume that a person with an ankle injury has a sprain. There are several other injuries that can mimic ankle sprains. These include ankle fractures, foot fractures, osteochondral injuries of the talar dome, and injuries of the peroneal tendons. As the treatment of these injuries differs from that of a simple ankle sprain, it is essential that clinicians keep each of these diagnoses in mind when treating a patient with a painful ankle.

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Grading Ankle Sprains

Ankle sprains are commonly graded according to the severity of the tear. In general, three grades are used. Grade I sprains are mild injuries in which the involved ligament(s) are partially torn but the structural integrity of the ligament is intact. With Grade I sprains there is no abnormal motion or laxity between the two bones which the ligaments connect. While these injuries are painful, it is usually possible to bear weight on the injured extremity. Grade II sprains are moderate injuries in which the involved ligament(s) tear further so that there is now laxity and abnormal motion present between the bones of the ankle. These injuries are more painful than Grade I sprains and often weight-bearing is not possible. Finally, Grade III sprains are severe injuries in which the ligament(s) are completely torn and compromised to the point that there is even further ankle laxity present. Grade III sprains are quite painful, usually to the point that it is not possible to bear weight on the injured leg.

The grading of ligament injuries is important for several reasons. First, it allows health care providers and patients to more accurately describe an injury. Second, it helps to guide treatment, as not all ankle sprains are treated the same. Finally, it also helps to establish a prognosis. More severe ankle sprains are prone to develop chronic ankle instability and recurrent sprains. Patients who have sustained these injuries must therefore be diligent in strengthening and rehabilitating their ankles following a sprain.

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Lateral Ankle Sprains

The most commonly injured ligaments in the ankle are those of the lateral ligament complex, located on the outer, or lateral, side of the ankle. The lateral ligament complex is comprised of three ligaments (figure 5): the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CL), and the posterior talofibular ligament (PTFL).

lateral ligament complex

Figure 5  – The lateral ligament complex

 

The Lateral Ankle Ligaments

ankle inversion

Figure 6 – Ankle Inversion

Most often, lateral ankle sprains are caused by an "inversion" injury of the ankle (figure 6). In these injuries a strong force pushes the foot inward underneath the leg. The foot then buckles inward, towards the opposite foot. An example of this mechanism is when an individual comes down from a jump and lands with the ankle turned inward. As the weight of the body further loads the ankle, the foot buckles inward and the lateral ligaments of the outer ankle are torn.

Individuals who have sustained lateral ankle sprains will seek medical treatment primarily because of pain. With more severe injuries they may be unable to bear weight on the injured ankle. Having a clear understanding of the mechanism of injury is an important step in establishing an accurate diagnosis. Another important part of the history is the time interval between the injury and the onset of symptoms. Patients who have sustained lateral ankle sprains often experience a brief, intense pain followed by a transient decrease in their symptoms. They may even resume participation in an athletic activity. This in contrast to an individual with an ankle fracture who, for example, will usually be immediately unable to bear weight on the injured limb.

On physical examination, swelling and bruising will be noted on the outer, or lateral, side of the ankle (figure 7). Often this takes several hours to develop, and the absence of immediate bruising and swelling does not mean that an ankle sprain has not occurred. Ecchymosis, which is characterized by dark purple discoloration of the skin and is caused by resorbing blood in the tissues underneath the skin, may also develop. This residual blood originates from the torn ligaments and other damaged tissues, which often bleed under the skin at the time of the injury.

Palpation of the injured ankle produces tenderness over the outer side of the ankle, just in front and below the fibula bone. It is important to note that the bones of the ankle should not be tender with palpation. If there is bony tenderness, the possibility of a fracture must be considered.

tenderness area with lateral ankle sprain

Figure 7 – Typical region of tenderness
with a lateral ankle sprain

The stability of the ankle is tested with the anterior drawer and talar tilt tests (photos 8 & 9), although pain and swelling diminish the reliability and usefulness of these tests when they are performed on a recently injured ankle.

During the anterior drawer test, the clinician will hold the leg with one hand while gently attempting to pull the foot forward with the other. This test is positive if there is excessive anterior translation of the foot with regard to the leg.

During the talar tilt test, the clinician holds the leg with one hand and then gently tilts the heel inward with the other. This test is positive if there is excessive tilting of the heel with this maneuver. Whether performing an anterior drawer test or talar tilt test, the uninjured ankle should always be tested first. This will serve as a baseline to determine an individual's normal degree of ligamentous laxity, or lack thereof.

 

 

anterior drawer test

Figure 8 – Anterior Drawer Test

talar tilt test

Figure 9 – Talar Tilt Test

A common dilemma faced by clinicians is whether or not to obtain x-rays of an individual with a suspected ankle sprain. While x-rays will not show an ankle sprain, they are often ordered to rule out fractures that might mimic an ankle sprain (figure 10).

broken fibula bone

Figure 10 – broken fibula bone

Because of the large numbers of ankle sprains sustained each day, however, this results in substantial costs and patient inconvenience. Accordingly, a set of guidelines called the Ottawa Ankle Rules was developed to help physicians determine when x-rays are necessary for patients with suspected ankle sprains.

The Ottawa Rules essentially state that x-rays are necessary only for individuals with suspected ankle sprains who cannot bear weight on the injured leg and for individuals with tenderness over the bones (as opposed to the ligaments) of the ankle. Extensive testing has been performed to validate the Ottawa Rules, and has shown that these guidelines are highly sensitive and specific.

The treatment of lateral ankle sprains depends largely on the severity, or grade, of the injury. Mild to moderate (Grade I and II) lateral ankle sprains are treated with a combination of rest and functional rehabilitation. The ankle may also be protected with a brace or fracture boot. Usually a "stirrup" brace (figure 11) will suffice, although for severe and some moderate sprains, a medical boot (figure 12) may be used.

 

 

stirrup brace

Figure 11 – Stirrup brace

walking boot

Figure 12– Walking boot

The RICE protocol is a practical regimen that is commonly used in the treatment of ankle sprains. This consists of Rest, Ice, Compression, and Elevation. Resting the ankle is accomplished by staying off of it as much as possible. Additionally, if the ankle is particularly painful, one or two crutches may be used so that only partial weight is born by the ankle. Icing the ankle is performed with ice packs. These can be purchased commercially or made at home.

Some individuals find a bag of frozen peas useful. These conform to the ankle, and, when thawed, can be put back in the freezer and used again. It is important not to fall asleep while icing the ankle, as this could potentially lead to frostbite-like injury. Generally, a regimen of 10 minutes of ice per hour several times a day is recommended. Compression is accomplished with an elastic bandage (e.g. Ace®). Care should be taken, though, not to wrap the ankle too tightly, as this can compromise blood flow.

elastic bandage wrap

Figure 13 – Using an elastic bandage (e.g ACE)
provides compression

vegetable therapy

Figure 14 – An easy way to ice an ankle.

Lastly, elevation is achieved by keeping the ankle above the level of the heart. This is best accomplished by lying flat on a bed or couch with two or three pillows under the injured ankle. If at work, sitting with the ankle elevated on an adjacent chair or stool is also useful.

The RICE protocol helps to decrease the inflammation, swelling, and pain, which occur immediately after an ankle sprain. Once these begin to resolve, physical therapy and early rehabilitation of the ankle may sometimes be initiated. If physical therapy is necessary, this usually begins 1 - 3 weeks after the injury, depending on the severity of the injury. Therapy typically consists of gentle stretching, strengthening, and "proprioceptive" exercises. Ankle stretching exercises help to decrease stiffness and preserve the ankle's normal range of motion. It is important, however, that patients with lateral ankle sprains initially avoid ankle inversion, as this will stretch the injured ligaments.

Ankle strengthening exercises will help both to stabilize the ankle and to protect the healing ligaments. The peroneal muscles are especially important in this regard. These muscles run along the outer side of the ankle, and resist ankle inversion, thereby shielding the lateral ankle ligaments from further stretch and injury.

strengthening exercises

Figure 15 – Standard strengthening exercises used after an ankle sprain

Finally, proprioceptive exercises will also protect the injured ligaments as they heal. Proprioception is the process by which the brain, either consciously or unconsciously, knows the spatial position of a part of the body. Sharpening and improving the brain's capacity to do so improves the reflexive mechanisms, which prevent a person with a healing ankle sprain from moving the foot and ankle in directions, which will stretch and further damage the injured ligaments.

The prognosis for Grade I and II lateral ankle sprains is good. In one large study of West Point Cadets, the average length of disability for individuals with Grade I injuries was 8 days and increased to 15 days for individuals with Grade II injuries.

Unlike Grade I and II lateral ankle sprains, the treatment of Grade III injuries is somewhat controversial. Grade III lateral ankle sprains are severe injuries in which there are usually complete tears of both the anterior talofibular and calcaneofibular ligaments. These injuries take longer to heal than less severe sprains. Additionally, individuals with Grade III sprains also have a higher likelihood of developing chronic ankle instability. For these reasons, it was previously felt that these injuries should be surgically repaired. However, studies have shown equally good results with non-operative treatment for these injuries. Based on these results, most orthopedists now recommend non-operative therapy with a carefully supervised rehabilitation protocol for Grade III ankle sprains. This is supported by the fact that with any surgical procedure there is a risk, albeit only a small one, of developing complications such as infection and nerve damage. The specific protocol used in Grade III sprains is similar to that used in Grade I and II sprains, although most individuals will require more time for the immediate swelling of the injury to resolve before rehabilitative exercises are initiated.

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High Ankle Sprains

High ankle sprains are most commonly caused by an external rotation injury in which the foot is forcefully turned outward, away from the midline of the body. These injuries are characterized by a tear of the syndesmotic ligaments of the ankle. As discussed above, the injuries hold the lower ends of the tibia and fibula bones together. There are actually five syndesmotic ligaments, and these include the anterior tibiofibular ligament, the posterior tibiofibular ligament, the transverse ligament, the interosseous ligament, and the interosseous membrane. Although high ankle sprains are much less common than lateral ankle sprains, they are now being recognized more frequently, especially in athletes. This is an important trend because high ankle sprains should be treated differently than lateral ankle sprains and can take twice as long to heal.

High ankle sprains are usually more severe injuries than lateral ankle sprains, and patients are often unable to bear weight on the injured extremity. The location of the pain and swelling correspond to the location of the anterior syndesmotic ligaments, which are just above the ankle. This helps to distinguish high ankle sprains from lateral ankle sprains, in which the pain is located more towards the outer, or lateral side of the ankle. Finally, if the deltoid ligament is injured, there may also be pain and swelling along the inner, or medial aspect of the ankle.

Two specific physical tests are commonly used to diagnose high ankle sprains. The first is called the squeeze test (figure 16).

squeeze test

Figure 16 – Squeeze test

external rotation test

Figure 17 – External rotation test

During this test, the tibia and fibula bones are manually squeezed together several inches above the ankle. If this produces pain further down the leg and in the ankle, a high ankle sprain has may have occurred. The second test is called the external rotation test (figure 17). During this test, the foot is manually externally rotated, but not inverted, by the examiner. If this is painful then a high ankle sprain is suspected.

If a high ankle sprain is suspected, x-rays of the ankle should be obtained. These serve two purposes. First, they will reveal a fracture if there is one present. Second, they will help to determine the severity of the injury. Severe high ankle sprains can be associated with a separation, or widening, of the tibia and fibula. This can be diagnosed on routine ankle x-rays. Unlike mild sprains, which can be treated without surgery, more severe injuries with widening usually require surgery.

High ankle sprains are more serious injuries that typically entail more damage than lateral ankle sprains. As such, it is important that patients with high ankle sprains be informed that their injury will take longer to heal.

High ankle sprains that are not associated with widening between the tibia and fibula can be treated without surgery. The RICE protocol is used initially, and consists of Rest, Ice, Compression, and Elevation. The RICE protocol helps to decrease the inflammation, swelling, and pain, which occur immediately after the injury. Resting the ankle is accomplished by staying off of it as much as possible. Additionally, if the ankle is particularly painful, one or two crutches may be used so that only partial weight is born by the ankle. Icing the ankle is performed with ice packs. These can be purchased commercially or made at home. Some individuals find a bag of frozen peas useful. These conform well to the ankle, and, when thawed, can be put back in the freezer and used again. It is important not to fall asleep while icing the ankle, as this could potentially lead to frostbite-like injury. Generally, a regimen of 10 minutes of ice per hour several times a day is recommended. Compression is accomplished with an elastic bandage (e.g. Ace®). Care should be taken, though, not to wrap the ankle too tightly, as this can compromise blood flow. Lastly, elevation is achieved by keeping the ankle above the level of the heart. This is best accomplished by lying flat on a bed or couch with two or three pillows under the injured ankle. If at work, sitting with the ankle elevated on an adjacent chair or stool is also useful.

Most high ankle sprains are initially treated with a walking boot or even a cast. The decision to use either a walking boot or cast depends on the severity of the injury and the preference of the treating physician. Both devices will restrict motion of the ankle as well as motion between the tibia and fibula, allowing the injured ligaments to heal. Again, it is important that injured individuals be informed that these injures take roughly twice as long to heal as lateral ankle sprains. In one large study, the average recovery time for these injuries was more than 40 days. As such, physical therapy may not be initiated for several weeks.

High ankle sprains that are associated with widening between the tibia and fibula (figure 18) usually require surgery. In these cases the widening between tibia and fibula is manually "reduced" and then held together with one or two screws (figure 19). The screws are inserted a few inches above the ankle joint and will prevent motion from occurring between the tibia and fibula as the ligaments heal.

widening between tibia and fibula

Figure 18 – Widening between the tibia and fibula following a complete tear of the "syndesmotic" ligaments

widening repaired with one screw

Figure 19 – This widening has been fixed with a single screw

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Medial Ankle Sprains

ankle eversion

Figure 20 – Ankle eversion

A medial ankle sprain occurs when the deltoid ligament is torn, located on the inner, or medial, side of the ankle. This ligament connects the medial aspect of the distal tibia (known as the medial malleolus) to the body of the talus and calcaneus bones. Isolated injuries of the deltoid ligament occur much less frequently than do injuries of the lateral ankle ligaments, and account for less than 5% of all ankle sprains. For this reason, a classification system for these injuries has not been developed. Isolated medial ankle sprains are caused predominantly by "eversion" injuries (figure 20) in which the foot and heel buckle outward, away from the other foot. With this, the deltoid ligament on the inside of the ankle is stretched or torn. An example of this mechanism is when a basketball player comes down from a jump and lands with his ankle turned outward. As the weight of his body further loads the ankle, the foot buckles outward and the deltoid ligament is torn.

Most often tears of the deltoid ligament occur in conjunction with either an ankle fracture (located on the outer side of the ankle) or a sprain of the syndesmotic ligaments (located just above the ankle). In a few individuals, deltoid sprains are associated with a fracture of the proximal portion of the fibula bone, near the knee. This fracture is known as a Maisonneuve fracture.

Patients with medial ankle sprains will seek medical attention because of pain on the medial, or inner, side of the ankle (figure 21). Often a "pop" is heard at the time on injury. If the sprain is severe, an individual will not be able to bear weight on the injured ankle. Physical examination of the injured ankle will reveal swelling and bruising on the inner, or medial side of the joint. Ecchymosis, which is characterized by dark purple discoloration of the skin and is caused by resorbing blood in the soft tissues under the skin, may also develop. Palpation will reveal tenderness below the tibia bone. Given the uncommon nature of isolated deltoid sprains, it is extremely important to thoroughly examine the entire ankle to assess for bony tenderness and injuries to other ligaments. It is also essential that the entire fibula bone be palpated and assessed for tenderness.

tenderness region with medial ankle sprain

Figure 21 – Typical region of tenderness with a medial ankle sprain

Because medial ankle sprains commonly occur in conjunction with an ankle fracture, x-rays of the ankle should be obtained whenever a medial ankle sprain is suspected. If there is tenderness over the fibula bone higher up the leg, leg x-rays should be ordered to determine if a fracture has occurred. X-rays will also help to assess the syndesmotic ligaments that hold the lower ends of the tibia and fibula bones together. If the syndesmotic ligaments are injured, widening between these bones may be present.

If the diagnosis of a medial ankle sprain is uncertain, an MRI scan may be performed. Unlike x-rays, which predominantly show bone, an MRI scan is able to reveal the ligaments, tendons, and cartilage of the ankle. If the deltoid ligament is injured, the scan will show either fluid within the ligament, stretching of the ligament, or a complete tear of the ligament.

Tears of the deltoid ligament that occur in conjunction with an ankle fracture do not need to be surgically repaired, despite the fact that the associated ankle or fibula fracture may need to be fixed with a plate and/or screws. In the vast majority of cases, the period of immobilization and restricted weight-bearing which is required to heal the ankle fracture will be sufficient to heal the torn deltoid ligament.

The treatment of isolated tears of the deltoid ligament is more controversial. This is due to the fact that these injuries are so uncommon that few studies have been done to determine the best way to treat them. This is especially the case with more severe sprains. Nevertheless, most orthopedists would agree that mild to moderate deltoid sprains should be treated with a brace or cast (see figure 11), which is worn for several weeks. Mild sprains can be treated with several weeks in a stirrup brace. Weight-bearing is increased as symptoms allow. Moderate sprains need to be treated with a more protective brace, such as a walking boot (see figure 12). Again, weight-bearing is typically increased as symptoms allow.

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