A large percentage of musculoskeletal injuries observed in the outpatient setting involve the ankle. Sprains constitute 85% of all ankle injuries. Of these, 85% are inversion sprains. Up to one sixth of participation time lost from sports results from ankle sprains. Proper rehabilitation begins with accurate diagnosis, because up to 40% of patients with untreated or misdiagnosed ankle injuries develop chronic symptoms. Most injuries respond to treatment. Pain reduction is essential, but improvement of any loss of motion,
Pathophysiology
The lateral ankle complex, which is composed of the anterior talofibular, calcaneofibular, and posterior talofibular ligaments, is the most commonly injured site.4, 5, 6 Approximately 85% of such sprains are inversion sprains of the lateral ligaments, 5% are eversion sprains of the deltoid or medial ligament, and 10% are syndesmotic injuries. The anterior talofibular ligament is the most likely component of the lateral ankle complex to be injured in a lateral ankle sprain. Osteochondral or chondral injuries of the talar dome should be considered when diagnosing an ankle injury.

Frequency
United States
Sprains of the lateral ankle complex make up 38-45% of all injuries in sports. In one study, 50% of patients with ankle sprains had recurrence.

Mortality/Morbidity
Each day approximately 25,000 people suffer an ankle sprain. Up to 40% of these individuals have residual symptoms due to chronic instability.7 Because instability is a potential problem following an ankle sprain, it is important that this injury be treated aggressively to prevent further disability.

Sex
No good data suggest a significant sex predilection for ankle sprains.

Age
Because older individuals tend to be less active than younger persons, and therefore often lack conditioning and proprioceptive conditioning, they are at risk for ankle sprain. For similar reasons, weekend warriors and overweight individuals are at risk for ankle injuries.



CLINICALSection 3 of 11 Authors and Editors Introduction Clinical Differentials Workup Treatment Medication Follow-up Miscellaneous Multimedia References


History
Determining the mechanism of injury is essential. Sudden, intense pain and rapid onset of swelling and bruising suggest a ruptured ligament. Suspect neurovascular compromise if the patient complains of a cold foot or describes paresthesias.4 Determine the presence of any complicating conditions, such as arthritis, connective tissue disease, diabetes, neuropathy, previous ankle sprain, or trauma.

Physical
Because most ankle sprains are tender during examination, observation can help the clinician to determine the severity of the injury.



Observe for obvious deformity and note the location of ecchymosis and edema.
The patient's ability to bear weight on the affected ankle and to ambulate also determines severity. In most cases, patients who are able to ambulate without severe pain are unlikely to have a fracture or instability.
Ankle sprains commonly are classified into the following 3 grades:

Grade I - These sprains produce a mild degree of swelling, and stretch has occurred to the ligamentous structures. Weight bearing is possible.
Grade II sprains - These injuries are characterized by a moderate degree of swelling and an incomplete tearing of ligamentous structures. Mild instability may be present, but a definite endpoint is found on ligamentous testing. Pain may be noted with weight bearing.
Grade III - These sprains produce severe swelling and are defined by the complete rupture of at least 1 ligamentous structure. Evidence of instability may be noted.
This grading system fails to characterize ankle injuries involving 2 or more ligamentous structures and excludes consideration of nonligamentous injuries.
Drawer and talar tilt examination techniques are used to assess ankle instability; however, the use of these techniques in acute injuries is in question because of pain, edema, and muscle spasm. The fibular compression, or squeeze test, is used if a syndesmotic or fibular injury is suspected.

Perform the anterior drawer test with the ankle at 90° to the leg. Grasp the heel and pull forward while, with the other hand, placing posterior force on the tibia. If the test is positive, the so-called suction sign occurs. Dimpling is observed at the anterolateral aspect of the ankle, indicating compromise of the anterior talofibular ligament. A firm endpoint will be absent.
The talar tilt test also is performed with the ankle at 90° to the leg. Abduct and invert the heel. If a firm endpoint cannot be felt when compared with the opposite ankle, suspect damage to the calcaneal fibular ligament. Note that the degree of tilt ranges from 0-23°.
To perform the squeeze test, place the thumb on the tibia and the fingers on the fibula at the midpoint of the lower leg; then squeeze the tibia and fibula together. Consider pain along the length of the fibula, which indicates a positive test result.
Related eMedicine topic:
Ankle Fracture


Causes
Typically, plantarflexion and inversion of the foot occur, perhaps as a result of moving on uneven terrain or of landing on the foot of another athlete.4 Overloading the peroneal muscles also may play a role. Invariably, ankle sprains involve trauma.



Forced, external rotation of the ankle results in a syndesmotic, or high, ankle sprain. These injuries occur less frequently than do inversion injuries, but they are more disabling and require a prolonged recovery period.
Recurrent ankle sprains or chronic, lateral instability are consequences of Grade III ankle sprains.7