A New “Rule” for Differentiating Stable Buckle and Other Distal Radius Fractures

wrist x-ray

Research over the last decade has shown that stable pediatric distal radius buckle fractures don’t need to be immobilized in a cast. A removable splint results in similar outcomes, while reducing costs and eliminating the need for follow-up orthopedic visits.

So as part of an ongoing quality improvement project, the Department of Orthopaedics at Nationwide Children’s Hospital changed its standard of care in 2016. Almost all wrist fractures definitively diagnosed as stable buckle were treated with a removable brace.

But there remained some uncertainty about what a “definitive diagnosis” might mean. The Department of Radiology did not previously differentiate between stable buckle fractures and potentially unstable distal radius fractures because all of them received casts, says Lynne Ruess, MD, a pediatric radiologist at Nationwide Children’s.

And it can be difficult to differentiate fracture types. Other institutions have reported poor agreement between original radiology reports and final diagnoses when radiologists were asked to distinguish the fracture types, and initial experience at Nationwide Children’s was similar. The two inflection points of a stable buckle fracture may look like the single inflection point of a potentially unstable distal radius fracture. An unstable fracture does need a cast and follow-up.

“I noticed that the two inflection points of a buckle fracture seemed to be further from the physis than the single inflection points of the unstable distal radius fractures,” says Dr. Ruess. “I wondered if we could measure the distance between the fracture and the physis and come up with a way to help guide providers to distinguish between these fracture types.”

Members of the Departments of Radiology and Orthopaedics at Nationwide Children’s did exactly that, and have now developed and published what they call the “1-cm Rule.” In children 7 years through 16 years of age, an isolated distal radius fracture is not likely to be a buckle fracture if the fracture-to-physis distance is less than 1 cm. Instead, it should be treated as potentially unstable.

There’s a corollary as well: Caution should be used in labeling a fracture as a stable buckle fracture if the fracture-to-physis distance is less than 14 mm on a posteroanterior (PA) radiograph or 13 mm on lateral radiograph.   

The authors of the study in Pediatric Radiology came to those conclusions after analyzing the records and measuring fracture-to physis distances of 203 children, ages 3 to 16 years, who presented with isolated distal radius fractures.

Only one of 106 children ages 7-16 had a buckle fracture with a fracture-to-physis distance of less than 1 cm on a PA projection, and no children did on a lateral projection. Diagnostic accuracy was high using the 14 mm cut-off for PA and 13 mm for lateral projection. The measurements for younger children, however, were not accurate in distinguishing buckle fractures.

This new rule is now being used at Nationwide Children’s to help determine whether a removable splint or cast is the most appropriate treatment for children with distal radius fractures, says Julie Balch Samora, MD, PhD, a surgeon and director of quality improvement in the Department of Orthopaedics.

“For now, we continue to have all children with distal radius fractures follow-up with orthopedic providers, because we want to confirm that our rule is correct, and that we are appropriately diagnosing the stable injuries,” says Dr. Samora. “In the future, we hope that we can eliminate this extra visit for children with stable distal radius buckle fractures, thus reducing both the financial and time burden for families, as well as allowing for best outcomes.”

Reference:

Iles BW, Samora JB, Singh S, Ruess L.  Differentiating stable buckle fractures from other distal radius fractures: the 1-cm rule. Pediatric Radiology. 2019 Mar; 49(3): 358-364.