Application of differentiation methods between postmortal and perimortal lesions to skeletrized human material

Introduction: In the analysis of bone fragments, searching for any lesion and ascertaining if it is occurred before, during, or after death have a great importance; although, the diagnosis between perimortal and postmortal lesions is made difficult by the similar bone structure affected by lesions. Fractures made near death occur in bones still rich in fibroelastic tissue and cells, whereas in postmortal lesions fractures occur in bones which have lost their fibroelastic and cellular contents, and therefore are less resistant and more easily broken. Three important characteristics have to be considered in order to establish when fracture is occurred: colour of edge, linearity of the fracture’s fissure and bone’s elasticity. The fracture’s edge and the surrounding bone tissue are similar in colour in perimortal lesions, whereas the edge is darker than bone’s section in postmortal lesions (in this case in fact soil blackens only the fracture’s fissure). Another useful parameter is the shape of the fissure, which is more irregular in perimortal lesions (the so-called “green wood lesions”) than in postmortal ones. Moreover a great importance has the presence of bone spicules, observed in perimortal lesions, which occurred in bone with a normal fibroelastic contents, but are absent in bones affected by postmortal lesions. This experimental study aims at pointing out the differences between postmortal lesions on cemeterial human bones and a group of cemeterial bones put in moistened soil. Methods: 19 femurs and 40 pairs of ribs taken from cemeterial bones were divided into two groups (each group included 40 ribs and 19 halves of femurs cut in the middle by hacksaw): a control group was subjected to contusion (by hammer) and blade lesions (by billhook). In the other group bones’ fragments were buried into small plastic basins filled up with soil, and then left in open air; basins were filled with water every day. Bones remained buried for different periods of time: 30 days, 45 days, 60 days, 90 days. Then the bones were drawn out of the basins and damaged with the same tools used in the control group: the new contusion and blade lesions were photographed and described with 5 parameters: irregularity of fracture’s edges, flattening of borders, number of bone spicules, crash resistance, colour of fracture’s fissure. For each parameter a score from 1 to 5 was established. Results: Results showed an increase in score of all the different parameters with time, both in femurs and in rib bones, affected by contusion and blade lesions as well, except the colour of fracture’s fissure, which didn’t change considerably; therefore, this is the only reliable parameter useful in the diagnosis between perimortal and postmortal lesions. Conclusions: The macroscopic analysis demonstrated an increase in similarity between lesions in the samples buried in wet soil and perimortal lesions with time, and this phenomenon is caused probably by the higher hydration of samples which longer remained under soil; this is more clear in rib bones, probably because of the lower thickness and the higher absorption of water. The wet soil may have increased surface elasticity of bone structure, with consequent jagged edges, high number of bone spicules, and irregular borders, characteristics of perimortal lesions; nevertheless the change in colour of fracture’s fissure, important diagnostic marker between postmortal and perimortal lesions, never occurred in samples put in wet soil, and therefore is the most important parameter in valuation of bone remains. Crash resistance resulted too much affected by external unverified variables