Discrimination between falls and blows from the localization and the number of fractures on computed tomography scans of the skull and the trunk.

The distinction between falls and blows is a common and difficult task in forensic sciences. One of the most often used criteria to address this issue is the hat brim line (HBL) rule, which states that fall-related injuries do not lie above the HBL. Some studies, however, have found that the use of HBL rule is not so relevant. This study assesses the aetiologies, the number of fractures, and their location on the skull and the trunk in a sample of 400 individuals aged 20-49 years, which were CT scanned after traumas. This may facilitate the interpretation of such injuries in skeletonized or heavily decomposed bodies in which soft tissues are no longer available. Our aim is to improve the distinction rate between falls and blows by combining several criteria and assessing their predictability. Skeletal lesions were analysed using retrospective CT scans. Cases selected comprise 235 falls and 165 blows. We registered the presence and the number of fractures in 14 skeletal anatomical regions related to the two different aetiologies. We showed that the HBL rule should be used with caution, but there is nevertheless a possibility of discussing the aetiology of blunt fractures. Possibly, parameters like the anatomical location and the number of fractures by region can be used to distinguish falls and blows.