Fractures within the first year of life, infants improve in motor skills, making this period as the mean age of fracture just after learning how to sit, learn to walk, and roll over, account for a small proportion of the total number of hospitalized skeletal fracture patients, but the incidence of fracture sites, treatments and the causes has its own characteristics. In the present study, we found that: (1) Among the 664 infants included in this study, injuries tended to occur at a younger age and the number of fractures peaked in the 151-240d group; there were more males than females; and conservative treatment was the primary treatment method. (2) The top three fracture sites were the skull, long bones of the limbs, and the clavicle. (3) The leading three causes of injury were locomotion injuries, falling or tripping (falling from a bed, table, chair, etc.), and birth injuries. (4) The interval between injury and hospital visit was ≤ 72 h in 554 cases, > 72 h in 110 infants. The latter included 69 skull fractures and 41 skeletal fractures. The main reason for this delay was the fact that the patients were transferred to our hospital due to unsatisfactory treatment at other hospitals.
Skeletal trauma and skull fractures have specific epidemiological characteristics, which differ between the pediatric and adult populations. The prevalence of fractures among children younger than 1 year is 0.3%, which is lower than the prevalence reported in other stages of childhood [3, 4]. But for infants whose bones are not fully developed, it can cause serious injuries. Trauma is one of the critical causes of mortality and morbidity among children. [8, 9] In China, epidemiological studies have been conducted on fractures in children of all ages, but fewer studies have focused on infant injuries. Furthermore, some of the epidemiological data are outdated or not updated in a timely manner. Thus, in order to prevent and reduce the harm caused by fractures, it is necessary to investigate the epidemiology of trauma, and hence examining the characteristics of pediatric fractures in this age group can help provide clinical evidence for further prevention guidance.
Changes in the epidemiology of fractures and etiology in terms of age
Infants under 1-year old experience rapid physical growth and developmental changes. At this stage infants are often exposed to dangerous environments but have not yet developed an awareness of danger of their surrounding environments. In our study, the causes of injury varied significantly by age. The 1-28d group had 101 cases, which accounts for the highest percentage (15.21%) of overall fracture cases. During this neonatal stage, the infants' head is usually large, with long torso, and the ratio of their head to the whole body is 1:4; since the infant’s motor system is not fully developed yet, the main cause of injury during this stage is birth injury. The 29-60d group had the lowest percentage of fracture cases. Due to the rapid physical growth of the infant, the number of fractures increased again, reaching a maximum of 190 cases in the 151-240d group (28.46%). The most common cause of injury in the 151-240d group was locomotion injuries, which accounts for 77 cases (40.74%) at this age group, when development has reached a new height, and infants are curious about everything around. In terms of motor development, infants can roll over, sit, move around, learn to walk which raises the risk of fractures.
Our noteworthy finding is that the most common cause of fractures in children was locomotion injuries (38.55%). The second most common cause of injury was falling from furniture (beds, chairs, tables) (19.58%), falling from arms of adult accounted for 11.45%, and stroller-related falls accounted for 3.01%. Sceats et al. noted that 41% of accidents among children younger than 1 year could be attributed to falls . Additionally, several studies have documented the risk of falls from beds, chairs , prams, changing tables, high-chairs [11, 12], and supermarket trolleys . Similarly, Pollack-Nelson et al.  showed that one-third of infant falls are specifically attributed to placing infant car seats on an elevated surface in the home. Studies have also shown that in 53% of falls related to buggies and prams, the safety harnesses were not being used at the time of the accident, and 5.9% of such falls resulted in skull fractures .
In this study, the most common fracture site was the skull (66.77%). Claydon et al.  noted that minor falls could lead to severe head injuries. Those head injuries are a particular concern due to the malleable nature of infants' skulls, which predisposes them to skull fractures and intracranial injuries . Warrington et al. found that falls occur in 22% of infants, but the injuries are mild and almost entirely confined to the head, with less than 1% of falls resulting in serious injury (i.e. concussions and fractures) . However, our study included 105 infants with skull fractures, who required surgical intervention. In addition, we found that the most common causes of skull fractures in infants were locomotion injuries (49.07%), followed by falling or tripping (21.63%). Young children are susceptible to many injury hazards, but have a limited ability to recognize hazards and anticipate the consequences of their actions. Moreover, infants at this age are often unable to protect themselves in the event of a fall. Infant in this age group (under 1 year) are always usually closely supervised. However, there were 24 cases in our study which the cause of the injury was unknown, and the chief complaint was that by the time the parents discovered the injury. Moreover, these children had already exhibited significant swelling and functional limitations of the affected limb. The reason may contribute to the difficulty to ascertain what happened and where infants are hurting as they lack verbal communication skills. And another reason may be that crying is the only language that infants can use to express their needs and physical status. However, in fact, it is difficult for the parents to understand the baby’s crying. To a large extent, the parents cannot tell in time what causes the infants crying, such as hunger, sleepiness, or trauma, especially for their parents or other caregivers without sufficient experience.
Strengthening public health education. The necessity of neonatologists to perform detailed physical examination for neonates.
An increase in physical activity accompanies the rapid growth and development of infants younger than 1 year, but lacks of hazard awareness and skills to avoid accidental injury. Thus, parents will need to increase their vigilance, and keep infants of this age group away from factors that could lead to injury. Hjern et al.  demonstrated that children of young mothers (aged under 24 years) are more likely to be admitted to hospital due to falls. Therefore, adults have a responsibility to protect their children by increasing the appropriate level of supervision [20, 21], and it is especially important to increase the outreach to younger parents. Morrongiello et al.  suggested that parental supervision is an essential factor in preventing domestic injuries among young children. Optimal supervision is defined as one where the child remains "visible and accessible" to the caregiver, and consists of three fundamental basic dimensions: attention, proximity, and continuity . The most effective way to prevent injuries in children is to keep them away from relevant hazards. For example, they should be protected during the toddler years by using walkers or carpets in children's living areas, guard rails can be added around cribs, and safety straps can be used when carrying children. As the infant grows and develops rapidly, the guardian must continually reassess the ability of protective barriers and restraints to ensure the safety of the child.
In this study, the 1-28d group had the highest overall fracture rate with 101 cases (15.21%), which were mainly for clavicular fractures due to birth injuries. Neonatal clavicular fracture is one of the most common complications of natural birth . This study included 52 cases (51.49%) of neonatal clavicular fractures are due to birth injuries, of which 47 were normal deliveries, 2 were forceps deliveries and 3 were cesarean deliveries. The most frequently cited risk factors for clavicular fracture due to birth injury were birth weight, shoulder dystocia, forceps delivery, and low Apgar score . The widely accepted hypothesis is that clavicular fracture is due to the impaction of the anterior fetal shoulder against the maternal pubic symphysis . However, in the present study, there were still 3 cases of clavicular fracture due to caesarean section, which suggests the possibility that caesarean section may not prevent the trauma caused by child birth trauma. Neonatal clavicular fractures are not as easy to diagnose, with some studies showing that more than 85% (46/53) of clavicular fracture cases are diagnosed within 3 days of birth. . We believe that the high-risk children with stable vital signs after birth, should undergo detailed examination by a neonatologist or child health specialist, even confirmation by chest X-ray, given that they show stable vital signs after birth.
The literature reports that road traffic injuries are the leading cause of infant and child mortality in both developed and developing countries . Car seats (including rear-facing and front-facing car seats, or booster seats) are important protective equipment for infant and children in vehicles, which can significantly reduce the risk of severe injuries and deaths caused by road traffic injury (RTI) [28, 29]. In infants (under 1 year) and toddlers (1–4 years), the correct use of car seats can reduce the risk of death by 71% and 54%, respectively . It is worth mentioning that in our study, there were 25 cases (3.77%) who were admitted to hospital due to road accident injuries, with the highest number being in the 181-210d groups, most were due to the lack of child safety seats installed in the car, causing the injuries during a car accident. China’s new traffic regulations now require the use of child safety seats for children under 4 years of age, and children under 12 years of age cannot ride on the passenger side. Furthermore, with the increase use of vehicles, it is necessary to strengthen the implementation of road safety strategies, such as installing speed bumps, improving emergency medical care for traffic accidents, and enhancing road safety enforcement . In addition, we recommend installing special child safety seats in private cars and even in public transport, in order to reduce child mortality and protect children from more serious high-energy severe trauma in the event of traffic accidents.
The importance of emergency surgeons to improve their knowledge orthopedics and neurosurgery
Data from the US Centers for Disease Control and Prevention show that between 2007 and 2013, the number of emergency department visits for traumatic head injury increased in the 0–4 years and 5–14 years age groups, with a 37.8% increase in the youngest age group . Research has shown that road traffic accidents are the most common cause of traumatic brain injury in China. The incidence of fall-related traumatic brain injury is expected to increase in the future . Based on the epidemiological characteristics of pediatric patients presenting with skeletal trauma and skull fractures, we believe that fractures in infants younger than 1 year require more attention than in other age groups. In addition, First-line emergency surgeons should improve their knowledge of orthopedics and neurosurgery, and collaborate with the neonatology and intensive care units in the hospital in a multidisciplinary manner, in order to provide timely and effective care for their patients.
When skeletal fracture cases occur in children, it should be first examined in specialized children’s hospitals
Most infants with accidental fractures will display behavioral patterns such as crying and screaming, exhibit movement dysfunction in the injured area, and show physical damage visible to the parent. In such cases, most parents are quick to transport the child to a medical center . We recorded the interval between the child's injury and hospital visit, and found < 6h: 264 cases, 6-11h: 114 cases, 12-23h: 39 cases, 24-47h: 100 cases, 48-71h: 38 cases, 72 h-5d: 61 cases, 6d-15d: 44 cases, > 16d: 5 cases. Among children with an interval of > 72 h, there were 69 cases of skull fractures and 41 skeletal fractures, among 69 cases of skull fracture including 20 depressed skull fractures, 19 of which were treated surgically, thus suggesting that skull fractures may be prone to delayed treatment. According to their detailed medical records, the main reason for this prolonged interval in skull fractures was that in 33 cases, the infants were transferred to our hospital from other hospitals due to unsatisfactory results, all of which were non-specialty children’s hospitals. According to the particular developmental status of infants, the treatment plan for adult fractures is not fully applicable to infants whenever possible, children should be first admitted in specialized children’s hospitals or general hospitals with pediatric trauma centers. Some adult specialists should also be trained in pediatric trauma and referral indications, in order to provide the best treatment plan for infants. In addition, a longer interval to hospital visit has been shown to be a significant risk factor for abuse injuries . However, no abuse injuries were found in our study.
Parents should also raise awareness of fractures in infants.
In addition, considering special characteristics of children during this stage, the study also finds out that among the 43 cases (39.09%) with longer delays in seeking treatment due to parental neglect- since infants cannot communicate with their parents verbally, which lead most parents do not notice the injury until more obvious signs of injury show – such as swelling of the affected limb and limited limb functions. Also, for cases involving that include head injuries, most of the infants did not exhibit disturbance of consciousness after the accident, without corresponding clinical phenomenon such as convulsions and vomiting, the family members can only noticed their injuries due to the subsequent development of hematoma in the head. The clinical symptoms and severity of skull fractures depend on the nature of the accident that led to the fracture. Depressed skull fractures are caused by strong external forces and often involve the underlying brain tissue, with depressed skull lacerating the dura mater below or penetrating the brain tissue. This type of depressed skull fractures often increases the likelihood of post-traumatic seizures and infections. Hence, among infants with clear history of trauma, parents should take their children to specialized children's hospital, even in the absence of expected behavioral patterns. Moreover, to prevent the persistence of any potential harm, it is important for parents to raise awareness on the risks of trauma, disseminate basic medical knowledge on the initial management of trauma, and reduce the number of secondary injuries in infants after trauma.
The establishment of pediatric trauma centers and professional pediatric trauma teams to handle such situations.
In the treatment of pediatric trauma, referrals to different levels of pediatric trauma centers should be made based on trauma scores. When trauma centers were established in the US and other developed countries, pediatric trauma did not receive sufficient attention. At that time, there were only a few adult trauma centers and no specialized pediatric trauma centers (PTCs). In the 1970s, the first batch of PTCs was launched in the US and achieved significant success thanks to the efforts of pioneers such as Kottmeier, Haller, Morse, and others. PTCs have now been established in many parts of the US [36–38]. However, this has not yet been replicated in China. A separate trauma center can be set up in specialist children's hospitals, or a relevant pediatric trauma team can be set up in adult trauma centers, with a view to providing efficient pediatric treatment. Pediatric trauma teams should include doctors trained in pediatric emergency medicine, pediatric orthopedics, pediatric surgery and pediatric anesthesiology. This will improve the prognosis of infants and those with more serious injuries. Since 2014, the Shenzhen Children's Hospital has fully implemented inter-hospital transfer among various hospitals in and around the Shenzhen area (including Dongguan city, Huizhou city, etc.). Within this system, the neonatal inter-hospital transfer team is composed of doctors and nurses with rich experience in rescue from the emergency department, neonatology department and neonatal intensive care unit (NICU). They can provide the best treatment measures for all types of newborns and young children in Shenzhen, including critically ill patients of pediatric trauma.
The PTC includes specialists in emergency medicine, surgery, otolaryngology, ophthalmology, anesthesiology, surgical intensive care unit, radiology, etc. Using a trauma information platform, the PTC can effectively integrate multidisciplinary treatment resources, such as pre-hospital emergency care, emergency department and ICU. The most significant advantage of this approach is that whether it is the information platform, treatment process, or staffing and equipment supply, all of these aspects adhere to the principles of the greatest efficiency and optimal process, which greatly reduces the rescue time. The new model of multidisciplinary joint diagnosis and treatment of children's traumatic diseases in the PTC utilizes the construction of a trauma treatment system feature pre-hospital care, information sharing and intra-hospital multidisciplinary coordination, which avoids the inadequate coordination among the various disciplines, thereby reducing the disability and mortality rates of infant with trauma, and improving the treatment standards of children with acute and critical trauma.