Although ankle sprains are common in older adolescent patients and young adults, isolated ankle sprains are not very common in younger children and in preadolescent patients. The physis (growth plate) in these younger children is much weaker than the surrounding ligaments, and is thus more susceptible to injury. Therefore in the pediatric population, injuries involving the growth plates (Salter-Harris injuries) must also be considered in addition to ligament sprains. The anterior talofibular ligament (ATFL) is the weakest of the 3 lateral ligaments and is the most commonly injured of the lateral ankle ligaments. (Note that ATFL can also stand for anterior tibiofibular ligament, however, in this case, ATFL will be used to stand for anterior talofibular ligament.) 65% of lateral ligament sprains are confined to the ATFL alone, while 20% have concomitant calcaneofibular ligament (CFL) tears. The ATFL can be palpated just inferior and anterior to the distal most aspect of the lateral malleolus.

The white arrow points to the region of the ATFL. Because the patient in this case has point tenderness in an area other than over the ATFL, he has therefore not sustained a typical ankle sprain. In comparison to these lateral ligaments, the medial, deltoid ligament has a fair degree of elasticity and is much more resistant to tears.Most injuries also occur while the ankle joint is in plantar flexion rather than in dorsiflexion. Anatomically, the talar dome is wedge-shaped, with the anterior aspect of the talus being wider than the posterior aspect. During dorsiflexion, this wider, anterior aspect of the talus is engaged within the mortise (formed by the distal tibia and fibula), and the joint is very stable. However during plantar flexion, the narrower, posterior aspect of the talus becomes engaged in the ankle mortise.