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Condition/Disorder Synonyms

  • Inversion ankle sprain

  • Lateral ankle sprain

  • ATFL sprain

  • ATFL tears

ICD-9-CM Code

  • 845.0 Ankle sprain

ICD-10-CM Code

  • S93.409A Sprain of unspecified ligament of unspecified ankle, initial encounter

Preferred Practice Pattern1

Key Features


  • Disruption of anterior lateral ligament of the ankle

    • May be acute or chronic

  • The anterior talofibular ligament (ATFL) restricts anterior translation of the talus

  • The ATFL also restricts inversion and adduction at the subtalar joint

  • Most commonly injured with rapid inversion, adduction, and plantarflexion movements, in either contact or non-contact situations

  • Pain and edema at lateral ankle

  • Can occur with structure progression to the calcaneofibular ligament and then posterior talofibular ligament

Essentials of Diagnosis

  • Positive anterior drawer test and talar tilt test

  • Ultrasonography, radiography, or MRI may be utilized in select cases.2

    • Ultrasonography or MRI is recommended following an inversion ankle sprain in a patient with chronic ankle instability

    • Radiographs utilized within the constraints of Ottawa ankle rules

    • ATFL tears are classified based on the anatomical degree of damage or functional stability found on clinical exam

    • Anatomical

      • Grade 1: partial microscopic tearing of the ligament, minimal to no loss of function, mild swelling and pain

      • Grade 2: partial macroscopic tearing of the ligament, with mild-moderate loss of function, moderate swelling/pain/tenderness

      • Grade 3: complete rupture with severe loss of function, severe swelling/pain/tenderness

    • Functional stability

      • Stable: no laxity with talar tilt or anterior drawer testing (Grade I)

      • Unstable: laxity with anterior drawer testing (ATFL, Grade II); laxity with both anterior drawer and talar tilt (ATFL and CF, Grade III)

General Considerations

  • May occur with concomitant calcaneofibular (CF) sprain, posterior talofibular sprain, synovitis, chondral lesion, or fracture

  • Most commonly sprained ankle ligament


  • Prevalent in athletes, though does occur in sedentary individuals

    • Most common in basketball, soccer, and football4

  • Males between 15 and 24 years old have higher rates of ankle sprains than female counterparts; females over 30 years old have higher rates than male counterparts.4

  • A previous ankle sprain is the strongest predictor of a subsequent ankle sprain.5

Clinical Findings

Signs and Symptoms6

  • Pain in lateral ankle or foot

    • Grade 1: minimal

    • Grade 2: moderate

    • Grade 3: severe

  • May posture in greater pronation to avoid plantarflexed/inversion moments

  • Edema lateral ankle

    • Grade 1: minimal

    • Grade 2: moderate

    • Grade 3: severe

  • Pain with palpation of ATFL

  • Possible inability to bear partial or full weight

  • Guarded active/passive inversion range of motion (ROM)

  • May have increased inversion passive ROM (positive Talar tilt test)

  • Decreased active/passive dorsiflexion ROM


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