Injury-mechanism directness as a key factor for fracture laterality in pediatric extremity fractures

Background: Associations between certain extremity fracture sites and laterality in pediatric trauma are well known, whereas the rationale for such laterality tendencies are unclear. We hypothesized that the laterality tendency of a specific fracture would be affected by directness of injury mechanism and not by the fracture site itself.Methods: We retrospectively enrolled 1382 children (aged 2-16 years) who were diagnosed with extremity fractures sustained during loss-of-balance situations and investigated the laterality tendencies (dominant vs. non-dominant extremity) of specific fracture sites. Multivariate analyses were sequentially performed to adjust for potential confounding variables-with and without injury-mechanism directness as a covariate.Results: In the upper extremities, the non-dominant side was more prone to fractures (p < 0.001), especially of the distal supracondylar humerus, radial and/or ulnar shaft, and distal radius. In the lower extremities, the dominant side was more frequently fractured (p < 0.001), especially at the tibial shaft and distal tibia. However, the predisposing effects of specific fracture sites on fracture laterality were not statistically significant when in analysis adjusted for injury-mechanism directness as a covariate. Fracture laterality was affected by whether the injury mechanism was direct or indirect. Indirect injury to the upper extremity was strongly associated with non-dominant arm injury (odds ratio 0.686 [95% CI 0.517-0.991]; p 1/4 0.009), whereas indirect injury to the lower extremity was strongly associated with dominant leg injury (odds ratio 2.138 [95% CI 1.444-3.165]; p < 0.001).Conclusions: Injury-mechanism directness, rather than fracture site itself, is a key factor that affects fracture laterality in pediatric extremity fractures. These findings are helpful for improving our under -standing of which factors may affect fracture laterality among children.(c) 2022 Published by Elsevier B.V. on behalf of The Japanese Orthopaedic Association.