Which aspect of the ankle is most commonly affected in an ankle sprain?

Lateral Aspect of the Ankle is Most Commonly Affected in Ankle Sprains

The lateral aspect of the ankle is most commonly affected in ankle sprains, with the anterior talofibular ligament (ATFL) being the most frequently injured ligament. 1, 2

Anatomical Distribution of Ankle Sprains

• Lateral ankle sprains account for approximately 75% of all ankle injuries, involving the lateral ligamentous complex (anterior talofibular ligament, calcaneofibular ligament, and posterior talofibular ligament) 2
• The anterior talofibular ligament (ATFL) is the most commonly torn ligament in ankle sprains, followed by the calcaneofibular ligament (CFL) 1, 2, 3
• Inversion injuries of the ankle account for 25% of all musculoskeletal system injuries and 50% of all sports-related injuries 1
• Medial sprains are less common than lateral sprains 1

Mechanism of Injury

• The most common mechanism for lateral ankle sprains is forced plantar flexion and inversion of the ankle as the body's center of gravity rolls over the ankle 2, 4
• This mechanism places the greatest stress on the ATFL, explaining why it is the most frequently injured ligament 2, 4
• High ankle (syndesmotic) sprains are caused by dorsiflexion and eversion of the ankle with internal rotation of the tibia 1

Clinical Assessment and Diagnosis

• Key physical examination findings associated with more severe ankle sprains include swelling, hematoma, pain on palpation, and a positive anterior drawer test 1
• The anterior drawer test can detect excessive anterior displacement of the talus onto the tibia, indicating ATFL tear 1
• The sensitivity (84%) and specificity (96%) of assessment using the anterior drawer test are optimized if clinical assessment is delayed for 4-5 days post-injury 1
• In cases where a hematoma is present with pain on palpation around the distal fibula and/or a positive anterior drawer test, a rupture of the lateral ankle ligaments likely exists 1

Imaging Considerations

• The Ottawa Ankle and Foot Rules should be applied to determine if radiography is necessary to rule out fractures 1
• MRI is highly accurate for diagnosing ligamentous injuries with excellent sensitivity (93%-96%) and specificity (100%) but is not routinely needed for uncomplicated lateral ankle sprains 1
• In cases of suspected high-grade ligament injuries, osteochondral defects, syndesmotic injuries, or occult fractures, an MRI can be performed 1

Treatment Approach

• For acute lateral ankle sprains, the PRICE protocol (Protection, Rest, Ice, Compression, Elevation) is recommended for the first 72 hours to control pain and swelling 1, 5
• Functional rehabilitation with early mobilization and proprioceptive training is preferred over immobilization 1, 5
• Semirigid or lace-up ankle supports provide better outcomes than elastic bandages for treatment and prevention of recurrent sprains 1, 5
• Proprioceptive training, especially ankle disk exercises, helps reduce the risk of recurrent ankle sprains 1, 5

Complications and Prognosis

• Approximately 80% of acute ankle sprains make a full recovery with conservative management 2
• However, 20% of acute ankle sprains develop mechanical or functional instability, resulting in chronic ankle instability 2, 6
• Common sequelae include persistent synovitis, tendinitis, ankle stiffness, swelling, pain, muscle weakness, and "giving way" 7
• Ankle sprains can also lead to chondral or osteochondral lesions of the talus, anterior or posterior ankle impingement, and injuries to the subtalar and transverse tarsal joints 3

Common Pitfalls to Avoid

• Excessive imaging when not indicated by the Ottawa Ankle Rules 5, 6
• Prolonged immobilization (>10 days) which leads to poorer outcomes 5
• Delaying the initiation of therapeutic exercises, which can prolong recovery and increase risk of recurrent injury 5
• Using compression bandages alone without proper functional support 5
• Discontinuing exercises once pain subsides, which increases the risk of recurrent injury 5