Rib Fractures in Infants: Retrospective Survey of Fractures and Biomechanical Study.

Abstract

Literature suggests that rib fractures are highly associated with abuse and the present understanding is that antero-posterior compression associated with the ‘shaken baby syndrome’ is their cause. However, this mechanism rests on a number of assumptions with little experimental data to support them. Recent work using a porcine model of fractures suggests that, in the case of lateral fractures this may be highly unlikely. This work shows a feasible alternate mechanism, that of blunt force trauma (BFT), for the cause of these lateral fractures. A piglet model is used and shows the ease with which ribs fracture as a result of BFT, compared to the difficulty of fracture seen previously in compressive injury. The initial development of a computational simulation of these ribs for use in injury scenarios is also outlined here.

Secondly, skeletal surveys from New Zealand’s largest children’s care facility, Starship Hospital, were examined to give a picture of non-accidental injury (NAI) and how its patterns compare with accidental injury in New Zealand. It has been found that, as in foreign studies, there are a number of lesions highly associated with abuse and these include rib fractures, which are highly specific (97%) for NAI. Unusuallyhigh frequencies of lateral-type rib fractures (46.4%) were found and half the cases were found to be unilateral. This is not wholly in line with the currently accepted idea that rib fracture is due to antero-posterior compression, in which bilateral, posterior fractures are said to be most common. Overall, this work brings into question the traditional mechanism of rib fractures, provides a highly useful snapshot of abusive injury in NZ and also sets a strong foundation for future work.