A Rare Combined Injury in Children during Side Impact: The Possible Mechanism and Treatment Results.

Objective: Proximal humeral fracture combined with contralateral midshaft clavicle fracture is an extremely rare injury in children. Few studies focus on the injury mechanism and treatment scheme. The aim of this study is to propose the possible mechanism of this injury and present the treatment results.

Methods: This retrospective study included children diagnosed with proximal humeral fractures combined with contralateral midshaft clavicle fractures from August 2016 to March 2019 in the corresponding author's institution. The patients received elastic stable intramedullary nails and external fixation as treatment. The radiological and clinical outcomes of treatments were evaluated using the imaging and the Constant-Murley score (CMS) in follow up.

Results: Twelve patients (eight males and four females) with an average age of 7.83 years old (age 5-12) were included in this research. All the patients had suffered a side impact in a road traffic accident or outdoor environment. Hypothesis about the mechanism was the proximal humerus was directly impacted at first and caused the surgical neck fracture, then the contralateral shoulder hits the solid object and the contralateral midshaft clavicle was fractured. During the average 45.2 months (range 36-57) follow-up, all the patient's fractures achieved clinical and radiological union before 14 weeks without complications. Every patient had a satisfactory score (range from 92 to 100) on the CMS criteria for both shoulders.

Conclusion: The hypothesis about the mechanism of this combined injury in this study sounds reasonable. It highlights the need for safety-related education about using a safety seat or wearing a seat belt to parents and caregivers, so as to avoid such injury even if the treatment with external fixation (EF) and proximal humeral and elastic stable intramedullary nailing (ESIN) showed good results.