Craniofacial Injuries Associated With “Mommy Bike” Child Seats in Japan

Objective: Bicycles are used for a wide range of purposes, including leisure, sports, commuting, and daily shopping. In Japan, the use of “mommy bikes” (MB), equipped with front and rear child seats, is legally permitted, a practice uncommon in other countries. This study aimed to characterize the overview of craniofacial injuries sustained while riding in MB child seats. Methods: This retrospective study included children who presented to the Advanced Center for Emergency Medicine and Critical Care at Saitama Medical Center for MB child seat injuries between May 2010 and December 2021, and who subsequently visited the Department of Oral and Maxillofacial Surgery for oral injuries. Results: Twenty-one children sustained oral injuries. The sex distribution was 11 boys and 10 girls, with a mean age of 2 years and 3 months. With the exception of one case, all injuries occurred in the front seat. The bicycle was predominantly stationary at the time of injury (18 cases, 85.7%), significantly more than when in motion (1 case, 4.8%) or unknown (2 cases, 9.5%). Soft tissue injuries were the most common (15 cases, 71.4%), followed by tooth injuries (with and without soft tissue injury) (4 cases, 19.0%), mandibular fracture (1 case, 4.8%), and mandibular contusion (1 case, 4.8%). Head injuries were observed in 11 cases (52.4%), but all were managed with observation. Conclusion: MB child seat craniofacial injuries most frequently occurred in the front seats occupied by young children, and when the bicycle tipped over while stationary. While most oral injuries were minor, sporadic mandibular fractures were observed, indicating the need for ongoing vigilance.