• IMPORTANCE
    • Lateral ankle injuries without radiographic evidence of a fracture are a common pediatric injury. These children are often presumed to have a Salter-Harris type I fracture of the distal fibula (SH1DF) and managed with immobilization and orthopedic follow-up. However, previous small studies suggest that these injuries may represent ankle sprains rather than growth plate fractures.
  • OBJECTIVES
    • To determine the frequency of SH1DF using magnetic resonance imaging (MRI) and compare the functional recovery of children with fractures identified by MRI vs those with isolated ligament injuries.
  • DESIGN, SETTING, AND PARTICIPANTS
    • A prospective cohort study was conducted between September 2012 and August 2014 at 2 tertiary care pediatric emergency departments. We screened 271 skeletally immature children aged 5 to 12 years with a clinically suspected SH1DF; 170 were eligible and 140 consented to participate.
  • INTERVENTIONS
    • Children underwent MRI of both ankles within 1 week of injury. Children were managed with a removable brace and allowed to return to activities as tolerated.
  • MAIN OUTCOMES AND MEASURES
    • The proportion with MRI-confirmed SH1DF. A secondary outcome included the Activity Scale for Kids score at 1 month.
  • RESULTS
    • Of the 135 children who underwent ankle MRI, 4 (3.0%; 95% CI, 0.1%-5.9%) demonstrated MRI-confirmed SH1DF, and 2 of these were partial growth plate injuries. Also, 108 children (80.0%) had ligament injuries and 27 (22.0%) had isolated bone contusions. Of the 108 ligament injuries, 73 (67.6%) were intermediate to high-grade injuries, 38 of which were associated with radiographically occult fibular avulsion fractures. At 1 month, the mean (SD) Activity Scale for Kids score of children with MRI-detected fibular fractures (82.0% [17.2%]) was not significantly different from those without fractures (85.8% [12.5%]) (mean difference, -3.8%; 95% CI, -1.7% to 9.2%).
  • CONCLUSIONS AND RELEVANCE
    • Salter-Harris I fractures of the distal fibula are rare in children with radiograph fracture-negative lateral ankle injuries. These children most commonly have ligament injuries (sprains), sometimes associated with radiographically occult avulsion fractures. Children with fractures detectable only by MRI had a comparable recovery with those with sprains when treated with a removable ankle brace and self-regulated return to activities. This work has the potential to simplify the care of these common injuries, safely minimizing the inconveniences and costs of overtreatment.