Kids' Lateral Ankle Injuries Rarely Require Casts

Diedtra Henderson

January 05, 2016

Lateral ankle injuries without radiographic evidence of a fracture are common injuries for children and rarely result in Salter-Harris I fractures of the distal fibula (SH1DF), according to a prospective cohort study published online January 4 in JAMA Pediatrics. Such injuries are more likely to be sprains that can be managed simply and cheaply with removable ankle braces.

"This study demonstrated that the commonly made presumptive diagnosis of SH1DF is rarely confirmed by MRI. These children most commonly have ligament injuries (sprains) occasionally associated with radiographically occult avulsion fractures," write Kathy Boutis, MD, MSc, Division of Emergency Medicine, Department of Pediatrics, the Hospital for Sick Children and the University of Toronto, Ontario, Canada, and coauthors.

Swollen, tender ankle injuries send more than 2 million US and Canadian children to the emergency department each year. For more than 50 years, pediatricians have followed the Salter-Harris classification as gospel, viewing children's ankle injuries that have tenderness overlying the physis of the distal fibula and no radiographic evidence of a fracture as undisplaced SH1DF, Dr Boutis and colleagues write. For children, this presumption means wearing an immobilizing cast for 3 to 6 weeks when they would rather be playing, as well as repeated radiographs, and follow-up in an orthopedic clinic.

The research team tested the conventional wisdom by measuring the actual frequency of SH1DF among 135 children aged 5 to 12 years with isolated lateral ankle injuries who arrived at the emergency departments of two tertiary care children's hospitals in Ontario from September 2012 to August 2014. Their mean age was 9.2 years, and 90% were girls.

All of the children had tenderness and swelling over the lateral aspect of the distal fibula at the level of the physis. None was able to place full weight on the injured ankle. Radiography for all showed open physes but no fracture, the authors write. The children had MRI for both ankles within 7 days of their injuries, and 129 did so again 1 month later.

Only 4 of the 135 children showed evidence of SH1DF on MRI, and only 2 of those showed an abnormal signal through the entire growth plate, the authors report.

In addition, 27 (22.0%) children isolated bone contusions and 108 (80.0%) had ligament injuries. Of those with ligament injuries, 73 (67.6%) were intermediate to high-grade and 33 (30.6%) were low-grade.

A companion editorial underscored the degree of overtreatment enabled by conventional wisdom: "[I]n children with presumed SH1DF, 33 children would need cast immobilization to treat 1 true SH1DF with no effect on clinically important outcomes," write Peter J. Gill, MD, DPhil, MSc, Department of Paediatrics, the Hospital for Sick Children, and Terry Klassen, MD, MSc, Children’s Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, Canada.

The editorialists praised the study as being "elegant in its simplicity, inspired by meticulous clinical observations and small hypothesis testing studies. Only 3% of children with ankle injuries diagnosed as SH1DF actually have fractures; most have ligamentous injuries like adults. But, irrespective of the presence or absence of a MRI-confirmed fracture, recovery is the same, and is excellent."

Dr Boutis and colleagues join the commentators in acknowledging that their study did not consider the long-term outcome of growth arrest. But they write that their findings could simplify care for common pediatric injuries. "[W]e advocate for a less-conservative approach focusing on a treatment strategy that minimizes patients' discomfort with a removable splint and allows for a return to activities as allowed by the patients' symptoms. Orthopedic consultation and radiographic follow-up are also not routinely necessary and should be reserved for patients who are not recovering as expected," the study authors conclude.

The study was supported by the Physician Services Inc granting agency, and the ankle braces were provided by DJO Global. The study authors and the commentators have disclosed no relevant financial relationships.

JAMA Pediatr. Published online January 4, 2016. Abstract Editorial

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