Differentiating stable buckle fractures from other distal radius fractures: the 1-cm rule.

BACKGROUND: Treatment pathways for isolated distal radius fractures in children are becoming more tailored to specific fracture types and include different management plans for stable buckle fractures versus potentially unstable distal radius fractures.

OBJECTIVE: To propose a measurement rule to aid in differentiating stable buckle fractures from other distal radius fractures in children.

MATERIALS AND METHODS: A medical record search identified 203 children with closed distal radius fractures during a 14-month period. A consensus of two senior readers served as a reference standard to distinguish buckle fractures from other distal radius fractures. We measured fracture-to-physis distance on posteroanterior (PA) and lateral radiographs for each of the isolated distal radius fractures. We analyzed diagnostic accuracy, using fracture-to-physis distance as a predictor for buckle fractures, in children ages 3-16 years. We used a receiver operating characteristic (ROC) curve to determine the cut-off values tested.

RESULTS: There were 148 buckle fractures (73%) and 55 isolated potentially unstable distal radius fractures (27%). For children 7-16 years, buckle fracture-to-physis distance was <1 cm in only 1/106 (0.9%) on the PA projection and none on the lateral projection. Diagnostic accuracy for buckle fracture diagnosis was 82% using a cut-off of 14 mm (PA) and 13 mm (lateral). In children 3-6 years old, the buckle fracture-to-physis distance was <1 cm in 1/42 (2.4%) on the PA radiographs and another 1/42 (2.4%) on the lateral radiographs. Diagnostic accuracy was low for younger children for all tested distances.

CONCLUSION: We propose utilizing a measurement rule to increase diagnostic accuracy for buckle fractures in children ≥7 years old. An isolated distal radius fracture in a child 7 years or older is not likely to be a buckle fracture if the fracture-to-physis distance is <1 cm.