Figure 1. Anteroposterior radiograph of the left ankle.
Figure 2. Lateral radiographic view of left ankle.
An 11-year-old boy presents with left ankle pain after twisting his ankle while playing basketball 2 days earlier. He has pain and swelling in the ankle and is having trouble bearing weight on that side. Mild bruising and swelling to the lateral ankle are found on physical examination. He has tenderness to palpation over the distal fibula and anterior talofibular ligament (ATFL). Anteroposterior and lateral radiographs are taken (Figures 1 and 2).
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Lateral ankle injuries are commonly seen in the pediatric population. In fact, ankle trauma is the most common pediatric injury.1 In skeletally immature patients it can be hard to conclude whether the injury is a lateral ankle sprain or a Salter-Harris type I (nondisplaced) fracture.1,2
A careful physical examination is critical in making the diagnosis; however, children often have difficulty pinpointing the exact location of the pain. Historically, the majority of lateral ankle injuries have been presumed to be growth plate injuries. The theory is that the physis is weaker than the surrounding ligaments in growing children and, therefore, injury to the growth plate is more likely.1
This theory has since been disproven. Boutis et al performed magnetic resonance imaging (MRI) on 135 pediatric patients who sustained a lateral ankle injury and found that almost all patients injured the lateral ligaments and not the physis. Only 4 of 135 patients (3%) who had an MRI were diagnosed with a Salter-Harris I fracture.2
Salter-Harris I fractures and lateral ankle sprains have a similar treatment course that includes short-term immobilization or bracing (usually 3 weeks depending on symptoms) with a gradual return to activities as tolerated. Physical therapy is an important treatment for lateral ankle sprains to regain ankle motion, reduce swelling, and strengthen the muscles.1,2
Misdiagnosing lateral ankle sprains for physeal injuries often prevents physical therapy referral and leads to unnecessary immobilization and follow-up radiographs.
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopaedics for Physician Assistants.
1. Rougereau G, Noailles T, El Khoury G, Bauer T, Langlais T, Hardy A. Is lateral ankle sprain of the child and adolescent a myth or a reality? A systematic review of the literature. Foot Ankle Surg. 2021; May 1. doi:10.1016/j.fas.2021.04.010
2. Boutis K, Plint A, Stimec J, et al. Radiograph-negative lateral ankle injuries in children: occult growth plate fracture or sprain?. AMA Pediatr. 2016;170(1):e154114. doi:10.1001/jamapediatrics.2015.4114