Use of a Template-Matching Clavicle Fracture Atlas for Surrogate Dating of Humeral and Femoral Fractures in Young Infants: A Six-Reader Study

Background: Fracture dating is important in suspected infant abuse. Birth-related clavicle fractures are common and may provide surrogates to aid infant long bone fracture dating. Objective: To assess the impact of a template-matching clavicle fracture timeline atlas on radiologists' performance in dating birth-related clavicle, humerus, and femur fractures in young infants. Methods: This retrospective study included infants with age ≤90 days who underwent a radiograph of a birth-related clavicle fracture from April 2021 to July 2024, or of a birth-related humerus or femur fracture from December 2011 to July 2024. All eligible radiographs of each fracture were identified, representing distinct observations for purposes of analysis. Patient age in days at the time of radiograph acquisition served as the reference standard for fracture ages. A non-rigid image registration technique was applied to a nonoverlapping pre-assembled database of birth-related clavicle fracture radiographs, to create a fracture dating atlas. Six readers (three trainees, three pediatric radiologists) independently reviewed radiographs in separate sessions without and with the atlas to estimate fracture ages. Interreader agreement was assessed using intraclass correlation coefficients (ICCs). Fracture aging performance was assessed using mean absolute errors (MAEs). Results: The analysis included 145 infants (87 male, 58 female) with 269 fracture radiographs (104 clavicle, 128 humerus, 37 femur). Mean fracture age was 26±19, 22±14, and 20±13 days for clavicle, humerus, and femur fractures, respectively. Interreader agreement for estimating fracture ages improved from moderate (ICC=0.69) without, to excellent (ICC=0.91) with, the atlas. MAE in fracture dating was significantly lower (P<.05) with than without the atlas for all six readers for clavicle fractures (range, 4.8-5.5 vs 5.8-10.1 days), all six readers for humerus fractures (6.0-12.1 vs 3.0-3.8 days), and five of six readers for femur fractures (7.4-17.2 vs 3.3-4.8 days). MAE without and with the atlas was 8.8 versus 4.3 days, respectively, across trainee readers and 8.4 versus 4.0 days, respectively, across attending readers. Conclusion: The fracture dating atlas yielded significant improvements in radiologists' performance for dating infant clavicle, humerus, and femur fractures. Clinical Impact: Clavicle fracture healing patterns can serve as surrogates for dating long bone fractures commonly encountered in infant abuse.