Probability of Occult Ankle Fracture Based on Radiograph-Measured Swelling

J Am Acad Orthop Surg Glob Res Rev. 2024 May 15;8(5):e23.00271. doi: 10.5435/JAAOSGlobal-D-23-00271. eCollection 2024 May 1.

Abstract

Introduction: Pediatric ankle injuries are a common presentation in the emergency department (ED). A quarter of pediatric ankle fractures show no radiographic evidence of a fracture. Physicians often correlate non-weight bearing and tenderness with an occult fracture. We present this study to predict the probability of an occult fracture using radiographic soft-tissue swelling on initial ED radiographs.

Methods: This is a retrospective study at a Level 1 pediatric trauma center from 2021 to 22. Soft-tissue swelling between the lateral malleolus and skin was measured on radiographs, and weight-bearing status was documented. Statistical analysis was conducted using Stata software.

Discussion: The study period involved 32 patients with an occult fracture, with 8 (25%) diagnosed with a fracture on follow-up radiographs. The probability of an occult fracture was calculated as a function of the ankle swelling in millimeters (mm) using a computer-generated predictive model. False-negative and false-positive rates were plotted as a function of the degree of ankle swelling.

Conclusion: Magnitude of ankle soft-tissue swelling as measured on initial ED radiographs is predictive of an occult fracture. Although weight-bearing status was not a sign of occult fracture, it improves the predictive accuracy of soft-tissue swelling.

MeSH terms

  • Adolescent
  • Ankle Fractures* / diagnostic imaging
  • Child
  • Child, Preschool
  • Edema* / diagnostic imaging
  • Emergency Service, Hospital
  • Female
  • Fractures, Closed* / diagnostic imaging
  • Humans
  • Male
  • Predictive Value of Tests
  • Probability
  • Radiography*
  • Retrospective Studies
  • Weight-Bearing