title: Radiograph-Negative Lateral Ankle Injuries in Children: Occult Growth Plate Fracture or Sprain?
abstract: OBJECTIVE
  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.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
  
  
  METHODS
  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
  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.
authors.affiliation: Division of Emergency Medicine, Department of Pediatrics, the Hospital for Sick Children and the University of Toronto, Toronto, Ontario, Canada.
authors.forename: Kathy
authors.initials: K
authors.lastname: Boutis
authors.affiliation: Division of Emergency Medicine, Department of Pediatrics, Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Amy
authors.initials: A
authors.lastname: Plint
authors.affiliation: Department of Diagnostic Imaging, The Hospital for Sick Children and University of Toronto, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Stimec
authors.affiliation: Department of Medical Imaging, Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Elka
authors.initials: E
authors.lastname: Miller
authors.affiliation: Department of Radiology, University of Saskatchewan and Saskatoon Health Region, Saskatoon, Saskatchewan, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Babyn
authors.affiliation: Division of Emergency Medicine, Department of Pediatrics, the Hospital for Sick Children and the University of Toronto, Toronto, Ontario, Canada.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Schuh
authors.affiliation: Department of Emergency Medicine, Kingston General Hospital and Queen's University, Kingston, Ontario, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Brison
authors.affiliation: Division of Orthopaedic Surgery, Department of Surgery, Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Louis
authors.initials: L
authors.lastname: Lawton
authors.affiliation: Division of Orthopaedic Surgery, Department of Surgery, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada.
authors.forename: Unni G
authors.initials: UG
authors.lastname: Narayanan
mesh_terms: D000203:Activities of Daily Living; D016512:Ankle Injuries / Q000150:complications* / Q000628:therapy*; D001915:Braces; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D005360:Fibula / Q000293:injuries*; D050723:Fractures, Bone / Q000175:diagnosis* / Q000209:etiology / Q000628:therapy; D006801:Humans; D015601:Injury Severity Score; D017844:Lateral Ligament, Ankle / Q000293:injuries; D008279:Magnetic Resonance Imaging; D008297:Male; D011446:Prospective Studies; D000072042:Salter-Harris Fractures; D013180:Sprains and Strains / Q000175:diagnosis* / Q000209:etiology / Q000628:therapy; D016896:Treatment Outcome