The influence of biomechanics on bruise formation

Contusions, or bruises, are injuries commonly observed within cases of assault. However, their interpretation is currently subjective, with the mechanics of their formation and how this affects their appearance over time, not completely understood. Research in this area is limited, with the primary aim being to reduce the subjectivity of visual interpretation. It is primarily focussed on colour pattern identification, with the most success being found using the L*a*b* system, where similar patterns were identified between individuals. However, with tools such as spectrophotometry being used for measurement (Mimasaka et al. 2010), a more simplistic approach of digital photography would be more appropriate. Visible light photography is the current method used for documenting contusions, however skin reflectance can cause inaccurate colour observation and reduce bruise visibility within images. The use of cross-polarisation and IR photography, could reduce this problem and even identify bruising not visible to the naked eye (Baker et al. 2013). Studies investigating the mechanics of bruise formation are limited. Pilot work has shown that tissue response varies significantly between two individuals, whilst also influencing the severity of bruising observed. A more extensive study is required to determine which factors, including age and BMI, influence both the tissue response (e.g. impacting force), and resultant bruising. Following ethical approval, blunt impacts are delivered to the thigh of volunteers under controlled conditions. High speed video recordings will allow for impact force estimation, while colour, cross-polarised and IR photography will be used to document and identify contusions. References Baker, H.C., Marsh, N. & Quinones, I., 2013. Photography of faded or concealed bruises on human skin. Journal of Forensic Identification, 63(1), pp.103–125. Mimasaka, S. et al., 2010. Spectrophotometric evaluation of the age of bruises in children: measuring changes in bruise color as an indicator of child physical abuse. The Tohoku Journal of Experimental Medicine, 220(2), pp.171–175.