Estimating the trauma-death interval : a histological investigation of fracture healing.

The accurate, reliable estimation of the ‘age’ of a fracture, or the time elapsed since trauma was sustained, has important implications In a variety of forensic contexts. Such information could greatly aid the forensic diagnosis of child abuse, the reconstruction of events during a violent incident such as homicide or a road traffic accident, and assist in the identification of unknown remains. Forensic fracture dating has largely relied on radiographical and histological evidence, but has lacked precision and consistency. The research presented here alms to test the hypothesis that correlations exist between the histologically- and immunohistochemically-observable phenomena at a fracture site and the known trauma-death interval of an individual. This was achieved by comparing the known trauma-death interval (TDI) to the extent of healing visible on histological slides prepared from formalin-fixed, paraffin-embedded, decalcified blocks of bone excised from the fracture site of 52 rib, skull and femur fractures from 29 individual forensic cases submitted to the Medico-Legal Centre Sheffield between 1992 and 2002. The slides were stained with haematoxylin and eosin to stain nuclei and cytoplasm, Peris’ Prussian Blue stain for haemosiderin granules, mono-clonal anti-CD68 antibody for osteoclasts, and anti-bone sialoprotein antibody as an osteoblast and osteocyte marker. Quantifiable parameters such as the percentage cover of red blood cells, of living and necrotic compact bone, and the size, abundance and dispersal of immuno-positive and inflammatory cells were examined and compared to the TDI using human observers and Scion Image histomorphometry software. Statistically significant correlations were found between TDI and the presence of haemosiderin granules later than three days post-trauma; and the dispersal and location of CD68 positive cells; as well as the estimated percentage cover of fibroblasts and red blood cells at the fracture site. Other trends and correlations were found, which contribute to the understanding of bone’s immediate responses to trauma. It is hoped that this research may aid the prediction of the time elapsed since trauma in a forensic context and broaden the scope of trauma analysis in forensic anthropology.