We have shown that fractures are rare in otherwise healthy children under the age of 12 months, with a 10-fold increase in those between 12 and 24 months. Moreover, that fractures to the femur and tibia predominate in the youngest as opposed to tibia and forearm fractures in the oldest age group, with an increase in forearm fractures with increasing age. While falls from a low height was the most commonly reported mechanism amongst those sustaining a fracture, crush-injuries predominated in children without a fracture. In 13.6% of the fractures, the mechanism was unknown.
The annual fracture incidence of 5.4 per 1000 found in the current study did not differ according to gender, as opposed to a male predominance seen in older children [2, 10, 11]. Except for a study by Clarke et al, reporting a similar fracture incidence of 5.3 per 1000 children under the age of two , the number of papers addressing fracture rates, types and mechanisms in otherwise healthy infants is sparse [4, 12–14]. As opposed to Clarke, we did not see any fractures in infants under 7 months of age, however, infants sustaining head- or high energy injuries were not included in our series as these children are routinely admitted to hospital. In total, Clarke found 15 fractures in those under 8 months, mostly skull and clavicle fractures. It is reasonable to believe that the occurrence of these fractures types is relatively similar in our population.
Of note is that nearly all children included in our study were otherwise healthy, with a normal bone structure judged radiographically. Still, most of both fracture-suspected injuries and fracture injuries in our study were due to low energy trauma, in this particular setting caused by falls from chairs, tables or beds, or falls from the child’s own height, as opposed to traumas caused by car accidents or falls from heights. However, the distribution of fractures, with femur fractures predominating in infants younger than one year of age is intriguing. Our estimated incidence rate of 0.36 per 1000 was significantly higher than that reported in a recent study from England . This study, including 1852 closed, isolated femoral shaft fractures in children aged 0–15 years, reported a mean annual incidence rate of 0.06 (95% CIs 0.02–0.10) per 1000 population for children aged < 1 year, rising to 0.12 (0.08–0,16) for those aged 1–2 years. The age of peak incidence was two years for both boys and girls, decreasing with increasing age. Falls less than two metres was the most common injury mechanism across all age categories, but this was most pronounced in the 18 months to 3 years age category. Unfortunately, the TARN (Trauma Audit & Research Network / NHS) database does not include the exact height fallen, nor was there any information about the child’s mobility. The authors state that most falls in toddlers represent a low energy impact which can result in spiral femoral shaft fractures. Their study found non-accidental injury (NAI) to be a suspected cause of femoral fractures in 3.8% of children. In contrast, one of five femur fractures in our cohort was suspect of NAI. The child, a 7 months old girl with an oblique/spiral fracture to the distal femur, was allegedly dropped onto the floor by a parent. She was admitted to hospital, where a skeletal survey showed an additional old fracture to the left clavicle. The remainder four femur fractures were seen in three non-mobile children aged 7–9 months, and in one 14-months-old, caused by falls from low heights/child’s own height or dropped by a parent. According to existing literature, a child sustaining a femur fracture has approximately a 1 in 3 chance of having being abused, and femoral fractures resulting from abuse are more commonly seen in children who are not yet walking . It is therefore of utmost importance that the possibility of NAI is considered in every non-ambulatory child presenting with a femur fracture.
Around half of the fractures were seen in children aged 8–23 months, with forearm and tibia/fibula fractures accounting for around 60%; findings that are in line with those reported by Clarke . The mechanism of these fractures was primarily fall from furniture or own height. In nearly 15% of the fractures, the no injury mechanism was offered, a figure that should be read with caution due to the retrospective nature of our study. Of note is, however, that an inconsistent fracture history was considered in almost 20% of the children as compared to 15% in Clarke’s study. Some of these children and their families were referred to the child protection service (CPS) for further assessments.
Similarly, an unexplained delay in presenting to an emergency department following an injury can be indicative of abuse or maltreatment [17, 18]. In our series, more than 50% of the 408 injured children were brought to the BLV within 6 hours of the injury, rising to 76% within 24 hours, as compared to 27% and around 50%, respectively, in the study by Clarke . 17 children attended BLV after more than three days, of whom 5 had fractures, and in 49 cases, the interval between injury and visit was unknown, of whom 18 had fractures. It is unclear how many of these children were referred to CPS, underscoring the importance of accurate and detailed medical notes in infants presenting with a fracture. In a study by Banaszkiewicz et al, the authors conclude that in 28%, abuse had been initially underestimated as a cause of injury . In order to systematically address possible NAI, new prospective studies with generalized forms and standardized follow up routines, could have the potential to identify, address and help young children and their families at an early stage after injury. However, the need for declarations of consent, is a limitation to this type of study.
Despite the limitations with the retrospective nature of our study, detailed data, a review of all the radiographs and the population-based approach strengthen its results.