Ankle Hyperinversion Injury: Most Commonly Injured Ligament
The anterior talofibular ligament (ATFL) is the most commonly injured ligament in ankle sprains caused by hyperinversion of the foot, making option B the correct answer. 1, 2
Mechanism and Epidemiology
Lateral ankle sprains account for approximately 75% of all ankle injuries, with the ATFL being the first and most frequently damaged structure. 3 The typical injury mechanism involves forced plantar flexion combined with inversion as the body's center of gravity rolls over the ankle—exactly the scenario described in this case. 3
- Inversion injuries of the ankle represent 25% of all musculoskeletal injuries and 50% of sports-related injuries 1
- The lateral ligamentous complex consists of three ligaments: ATFL, calcaneofibular ligament (CFL), and posterior talofibular ligament (PTFL) 3
- The sequential injury pattern follows: ATFL first (most common), then CFL, and rarely PTFL 3, 4
Why Not the Other Options
The deltoid ligament (option A) is injured in eversion injuries, not inversion injuries. 1 This medial ligament complex is stressed when the ankle is forced into eversion and external rotation—the opposite mechanism from what occurred in this patient.
The spring ligament (option C) is not typically involved in acute ankle sprains and is more relevant to chronic conditions affecting the medial longitudinal arch.
The posterior talofibular ligament (option D) is the strongest of the lateral ligaments and is rarely injured except in severe trauma with complete disruption of the entire lateral complex. 3
Clinical Relevance
- MRI studies demonstrate diagnostic accuracy of 77%-92% for detecting ATFL tears, with the ATFL being identified as torn far more frequently than other lateral ligaments 1
- Approximately 80% of acute ankle sprains recover fully with conservative management, while 20% develop chronic instability—emphasizing the importance of proper initial diagnosis and treatment 3
- The anterior drawer test specifically detects ATFL injury by demonstrating excessive anterior displacement of the talus 2
Common Pitfall
Do not confuse lateral ankle sprains (inversion injuries affecting ATFL) with high ankle sprains (syndesmotic injuries from dorsiflexion-eversion-external rotation). 1, 2 High ankle sprains involve the tibiofibular ligaments and require different management with longer recovery times.