Magnetic resonance imaging of clinically suspected Salter–Harris I fracture of the distal fibula

Boutis, Kathy; Narayanan, Unni G.; Dong, Frederik F.T.; MacKenzie, Heather; Yan, Hanmu; Chew, Derek; Babyn, Paul

doi:10.1016/j.injury.2010.04.015

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Volume 41, Issue 8 , Pages 852-856, August 2010

Magnetic resonance imaging of clinically suspected Salter–Harris I fracture of the distal fibula

Kathy Boutis
- Division of Emergency Medicine, Department of Pediatrics, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON M5G 1X8, Canada
- Corresponding author. Tel.: +1 416 813 8982; fax: +1 416 813 5043.
Unni G. Narayanan
- Division of Orthopedics, Department of Surgery, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
Frederik F.T. Dong
- School of Medicine, University of Toronto, Toronto, ON, Canada
Heather MacKenzie
- School of Medicine, University of Toronto, Toronto, ON, Canada
Hanmu Yan
- School of Medicine, University of Toronto, Toronto, ON, Canada
Derek Chew
- School of Medicine, University of Toronto, Toronto, ON, Canada
Paul Babyn
- Department of Radiology, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada

Accepted 14 April 2010.

Abstract

Objectives

In skeletally immature children, isolated lateral ankle injuries without radiograph-visible fractures are often diagnosed with Salter–Harris I fractures of the distal fibula (SH1DF). However, recent magnetic resonance imaging (MRI) evidence in children suggests that sprains may be more common than previously thought.¹⁷ Thus, the main objective of this study was to determine the rate of MRI-confirmed SH1DF among cases where this diagnosis was made presumptively, based on clinical findings. In ankle injuries where there is no MRI evidence of SH1DF, another aim is to detect the pathology which gives rise to this clinical scenario.

Methods

This was a prospective cohort study performed at a tertiary care paediatric centre. Eligible patients included skeletally immature children with acute ankle injuries presenting with difficulty weight bearing and maximal tenderness and swelling over the distal fibular growth plate (lateral malleolus). Enrolled patients had ankle radiographs at the Emergency Department (ED) visit, MRI within 1 week of the injury, and repeat ankle X-rays at 4 weeks. All images were reviewed by two radiologists and an orthopaedic surgeon. Discrepancies between reading physicians were resolved by consensus agreement.

Results

Eighteen patients were enrolled into the study from September 2008 to August 2009. Mean (SD) age of participants was 8.7 (2.0) years. None of the 18 patients had evidence of fibular growth plate injury on MR imaging. Patients often had more than one abnormal finding on MRI. Fourteen (78%) had evidence of ligamentous sprains, 11 (61%) had bony contusions, one patient (6%) had a subtle fibular avulsion fracture, and another was found to have a minor articular cartilage injury. At 4 weeks, only one patient's radiographs demonstrated a healing fracture, which corresponded with the avulsion fracture case. All patients had returned to full weight bearing by 4 weeks.

Conclusions

In this series, the clinical diagnosis of SH1DF was incorrect in 100% of cases. Instead, in almost 90% of these patients, MRI identified ligamentous sprains and/or bony contusions. These results may influence the way children who present with this common clinical scenario are managed since the vast majority of children in this study actually had sprain/contusion injuries and none had SH1DF.

Keywords: Paediatric, Magnetic resonance imaging, Ankle, Growth plate, Physis, Fibula