What aspect of the ankle is most commonly involved in an ankle sprain?

Lateral Ligaments Are Most Commonly Involved in Ankle Sprains

The lateral stabilizing ligaments, particularly the anterior talofibular ligament (ATFL), are most commonly involved in ankle sprains. 1

Anatomy of Ankle Ligament Involvement

• The lateral ligament complex consists of three main ligaments: anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), and posterior talofibular ligament (PTFL) 1, 2
• The ATFL is the most frequently injured ligament in ankle sprains, often followed by injury to the CFL 2, 3
• The PTFL is the least commonly injured of the lateral ligaments 2, 4

Mechanism of Injury

• The typical ankle sprain is an inversion injury that occurs when the ankle is in a plantar-flexed position 1
• This mechanism puts the greatest stress on the lateral ligaments, particularly the ATFL 2, 3
• Inversion injuries account for 25% of all musculoskeletal injuries and 50% of sports-related injuries 1

Anatomical Considerations

• The ATFL has an average length of 14 ± 2.4 mm and width of 7.6 ± 2.0 mm 5
• The CFL is typically longer at 18.4 ± 3.9 mm with a width of 5.2 ± 1.3 mm 5
• The PTFL is the longest of the three at 20.9 ± 3.3 mm with a width of 6.2 ± 1.4 mm 5
• The lateral ligament complex is inherently weaker than the medial (deltoid) ligaments, making it more susceptible to injury 5

Classification of Ankle Sprains

• Ankle sprains are classified into three grades based on severity 1:
  • Grade I: Mild sprain with minimal damage to ligament fibers
  • Grade II: Moderate sprain with partial ligament tears
  • Grade III: Severe sprain with complete ligament rupture 1

Less Common Ankle Sprain Types

• High ankle (syndesmotic) sprains involve the tibiofibular ligaments and occur through dorsiflexion and eversion of the ankle with internal rotation of the tibia 1
• Medial ankle sprains involving the deltoid ligament are less common than lateral sprains 3, 6
• Complete ruptures of both medial and lateral ligaments (luxatio pedis cum talo) are extremely rare 6

Clinical Implications

• 80% of acute ankle sprains make a full recovery with conservative management 2
• 20% develop mechanical or functional instability resulting in chronic ankle instability 2, 4
• Proper diagnosis of which ligaments are involved guides treatment decisions and rehabilitation protocols 1, 3
• The anterior drawer test specifically assesses ATFL function, while the inversion tilt test evaluates both ATFL and CFL function 4

Common Pitfalls in Management

• Excessive imaging when not indicated by the Ottawa Ankle Rules 1, 3
• Unwarranted non-weight bearing and immobilization can delay recovery 3, 6
• Inadequate rehabilitation of proprioception can lead to recurrent sprains 1, 3
• Failure to recognize and address subtalar joint involvement in severe inversion injuries 4

Understanding which ligaments are most commonly involved in ankle sprains helps clinicians focus their examination, select appropriate imaging when necessary, and implement targeted rehabilitation strategies to improve outcomes and prevent chronic instability.