The risk of pediatric bicycle handlebar injury compared with non-handlebar injury: a retrospective multicenter study in Osaka, Japan

The numbers of bicycles and associated riders have increased, and bicycle-related injuries have become a major health problem [6]. Bicycle trauma comprises a significant proportion of trauma in children. However, the risk of pediatric bicycle handlebar injury has not been emphasized. In 1997 in the United States, 1.15 per 100,000 subjects 19 years and younger were estimated to have suffered serious abdominal and pelvic organ injury leading to hospitalization that was associated with non-motor-vehicle bicycle handlebar accidents [5]. Winston et al. [7] considered handlebars as hidden spears because impact with handlebars might be accompanied by visceral organ injury through the concentration of an external force applied by the end of the handlebar to a child’s body.

The typical mechanism of pediatric bicycle handlebar injury is a falling accident in which the child loses control of the bicycle, begins to fall, the front wheel turns to the side, and the end of the bicycle handlebar strikes the neck, chest, abdomen, or pelvic area of the rider [7, 8]. We consider that pediatric bicycle handlebar injury can be caused by the immature decision-making ability of the child, the impact caused by sudden braking or collision, and the insufficient muscular power of the child’s body to withstand such impacts. About 90 % of patients with significant intra-abdominal organ injury were reported to have visible skin bruises from handlebar contact [9, 10] such as that shown in Fig. 1a.

Direct-impact handlebar injuries to the liver, spleen, pancreas, duodenum, intestines, kidney, urethra, abdominal wall, and major vessels have been reported [4, 8]. The rate of handlebar injuries to parenchymatous organs such as the liver, kidney, pancreas, and spleen reportedly ranges from 20 to 37 % [4, 11‐13], and gastrointestinal perforation has been reported in 9–10 % of children with handlebar injuries [4, 11, 12]. Cevik et al. [10] reported that 85.7 % of children who sustained direct-impact handlebar injuries required operative intervention. In our study, 50.0 % of the children who sustained direct-impact handlebar injuries required operation or TAE intervention (Tables 1 and 2). These are surprisingly high rates, which indicate that children with handlebar injuries should be examined carefully.

Traumatic abdominal wall hernia is a well-known complication of handlebar injuries and is defined as herniation through disrupted musculature and fascia associated with blunt trauma, without skin penetration because of the skin’s elasticity, and with no evidence of prior hernia defect at the site of injury [4, 14, 15]. However, traumatic abdominal wall hernia is rare, so due to a lack of knowledge of this condition, apparent clinical signs associated with this injury might easily be missed [16]. Two of the patients in the present study had injuries to their abdominal wall musculature and required surgical repair (Table 2, Fig. 1). Knowledge of the mechanism of trauma to the abdomen and visible handlebar skin bruises, if they exist, can help the physician to suspect the presence of traumatic abdominal wall trauma.

Falling while riding a bicycle occurred significantly more frequently and GCS on hospital arrival was significantly higher in the HI group compared with the NHI group (Tables 1 and 4). It is possible that the severity of pediatric handlebar injuries is underestimated by parents, witnesses, and the ambulance crew at the scene of an accident. Thus, transfer from another hospital occurred significantly more frequently and the time from accident to patient arrival at our emergency centers was significantly longer in the HI group (Table 4). In our study, one patient with pancreatic injury was not transferred to our center until 48 h after the injury (Table 2). The severity of pediatric bicycle handlebar injury might often be underestimated when based on the mechanism of the accident or the level of consciousness of the patient. We suggest more liberal use of CT scanning in the assessment of severe handlebar injury, at least for those injuries involving the abdomen.

There are some limitations in this study. First, it is a retrospective study. We collected patient information only from patient medical records. Second, study periods are different for each medical institution because medical records must be preserved for at least 5 years in Japan. Third, the medical institutions participating in this research were all urban tertiary emergency centers in Osaka, Japan. In major metropolitan areas of Japan, hospitals are categorized into three levels of emergency care (Primary emergency care: for patients with low-acuity conditions who can be safely discharged home; Secondary emergency care: for patients with moderate-acuity conditions who require admission to a regular inpatient bed; and Tertiary emergency care: for patients with high-acuity conditions who require admission to the ICU). Therefore, the subjects of this study were urban residents, and they had been judged as having severe or suspected severe trauma at the accident scene or initial medical institution before they were transported to our centers. This might lead to the difference in sample size of the HI and NHI groups in the present study. The research data does not cover all pediatric bicycle accidents. More comprehensive research into pediatric bicycle injuries would be desirable in a future study. Fourth, adult patients with handle bar injury were not included in this study. There is little documentation on bicycle handle bar injury in adult patients because of the following possible reasons: i) the abdominal muscles of adults are more well developed than those of children, ii) adults are less inclined to ride bicycles as recklessly as children do, and iii) adults generally can better perceive risks than children can [17].

As a preventive strategy for traumatic handlebar injury in the future, it might be effective to modify the shape of the ends of the handlebars, limit the side-to-side rotation of the front wheel fork assembly, and promote the wearing of an abdominal protector to prevent pediatric handlebar injuries.