Background A fall-height threshold is important when evaluating the likelihood of structural head injury or abusive head trauma. This study investigates witnessed falls to correlate the fall characteristics with the extent of injury.

Method Case–control study of children aged ≤48 months who attended one hospital following a fall from <3 m (10 ft), comparing cases who sustained a skull fracture or intracranial injury (ICI) with controls, who had minor head injuries. Characteristics included: the mechanism of injury, surface of impact, site of impact to the head and fall height.

Results Forty-seven children had a skull fracture or ICI, while 416 children had minor head injuries. The mean fall height for minor head injuries was significantly lower than that causing skull fracture/ICI (p<0.001). No skull fracture/ICI was recorded in children who fell <0.6 m (2 ft), based on the height of the head centre of gravity. Skull fractures/ICI were more likely in children aged ≤12 months (p<0.001) from impacts to the temporal/parietal or occipital region (p<0.001), impacts onto wood (p=0.004) and falls from a carer's arms, particularly when on stairs (p<0.001). No significant difference was reported between the mean fall heights of children who had a simple skull fracture (n=17) versus those who had a complex fracture or ICI (n=30).

Conclusions An infant is more likely to sustain a skull fracture/ICI from a fall above a 0.6 m (2 ft) threshold, based on the height of the head centre of gravity, or with a parietal/temporal or occipital impact. These variables should be recorded when evaluating the likelihood of skull fracture/ICI.