Subperiosteal new bone formation with the distal tibial classic metaphyseal lesion: prevalence on radiographic skeletal surveys

Background: The classic metaphyseal lesion (CML) is a strong indicator of infant abuse, and the distal tibia is one of the most common sites for this injury.

Objective: To determine the prevalence of subperiosteal new bone formation accompanying the distal tibial CMLs identified on infant skeletal surveys.

Materials and methods: Skeletal surveys performed for suspected infant abuse (2005-2017) were reviewed. Inclusion criteria were 1) anteroposterior (AP) and lateral radiographs of a distal tibial CML from the initial survey, 2) AP radiograph from the 2-week follow-up survey, 3) additional fractures, 4) child protection team consults and 5) mandated report filing for suspected abuse. We identified 22 distal tibial CMLs from 16 infants. Radiographs of these lesions were shown on the picture archiving and communication system to two blinded pediatric radiologists. Readers indicated the presence/absence of subperiosteal new bone formation on individual and combinations of images.

Results: Inter-reader agreements were fair (kappa=0.47). The prevalence of subperiosteal new bone formation on initial AP radiograph was 34%. Significant increases in the prevalence were found with the addition of follow-up AP radiograph (57%; P<0.001), initial lateral radiograph (57%; P=0.002) and follow-up AP plus initial lateral radiographs (71%; P<0.001). Statistically significant increases in prevalence were also noted when the third view was added to the other two views (increase of 14%; P=0.024).

Conclusion: Even when skeletal surveys include initial AP, lateral and follow-up AP radiographs of the tibia, nearly one-third of distal tibial CMLs will fail to demonstrate subperiosteal new bone formation.