1. Introduction

Bone traumas detected on skeletons were described by Dirkmaat et al. (2008) as a moment frozen in time which consistently contributes to understanding what had happened to the deceased individual. In forensic sciences, it is of particular importance to identify the type of injury inflicted and the weapon that caused it [1]. Accordingly, several different types of skeletal traumas can be distinguished as cutting wounds, blunt force traumas, sharp force traumas, chop wounds, stab wounds, ballistic wounds and several others [24]. Yet, another crucial aspect in the evaluation of skeletal traumas is to determine whether the injury occurred long before death (ante-mortem), at death or shortly before death (peri-mortem), or long after death (postmortem). Peri-mortem injuries may help in defining the cause of death, whereas ante-mortem injuries detected on the skeleton may be useful for the identification of the victim. Finally, post-mortem injuries can provide indications about the fate of the body between death and discovery. To help in the distinction of ante-, peri- and post-mortem skeletal injuries, we have generated a new user-friendly diagnostic form, which resumes the observations of several scholars [2,514] (Fig. 1). The analyses of the injuries are mainly based on morphological features detectable macroscopically, yet we suggest to integrating the information with radiological, microscopic and chemical techniques [4,15,16], when necessary. Hereafter, we show the employment of the evaluation form on two case-studies with multiple injuries, thus of difficult interpretation.

2. Timing and interpretation of skeletal injuries

Injuries occurred during life are characterized by bone remodelling due to the ability of the bone tissue to regenerate [17], whereas injuries produced on the skeleton, i.e. on the dry bone (dry fracture), are identifiable on the basis of characteristic bone patterns due to the loss of tissue elasticity [13,18]. Indifferently if they are intentionally inflicted or due to taphonomic processes, post-mortem injuries show an irregular fragmentation of the bone, with sharp margins and a colour of the edge surfaces, which differs from the rest of the bone [17]. More difficult is to distinguish between injuries occurred shortly before or shortly after the death [15,18] since both kinds of peri-mortem injuries show patterns that depend on the elasticity and plasticity of the living tissue with smooth edges of the same colour as the nearby bone. Taking into account the considerable literature that has been devoted to this topic in forensic anthropology [2,6,13,1922] we have summarized the characteristics of ante-, peri- and post-mortem injuries in a specific evaluation form (Fig. 1), which offers a synthetic description of each feature and specific references from the literature. To facilitate the identification and interpretation of traumas, we integrated the descriptions with pictures.

3. Case studies

We isolated two interesting cases of trauma found among 122 skeletons dating back to the 17th-19th centuries from the cemetery of the San Biagio church (Ravenna, Italy). Sex, age at death and stature of the skeletonized individuals were determined using standard anthropological methods [2335]. Cranial and post-cranial macroscopic evidences of injuries were examined in depth with a magnifying glass and a light microscope, to reduce the risk of misinterpretation. Radiographic and histological techniques were also employed to reinforce the evidence. Analysis and interpretation of the injuries were carried out using the new evaluation form (Fig. 1) and reported in Table 1. Injuries features of both cases are reported in Table 2.

3.1. Case 1 The individual US-114 was a 4555 years old man, 169.5 4.3 cm tall. A deep injury was detected on the right supraorbital margin of the frontal bone (Fig. 2a). The injury appears fairly large with irregular edges and shape. The surface interested by the direct kerf is smooth with some parallel striations that form a 90 angle with the transverse plane. All around the hit area, there are evidence of bone resorption and remodeling (bone spicules and osteolytic reactions) [2,3638] (Fig. 2b,c,d,e). Microscopic signs of specific cell activity are presents, the lamellae appear smoother due to advanced osteoblastic activity, while the presence of several Howship's lacunae resulting from the osteoclastic activity are already visible (they occur usually 4 days after the trauma) [3941], as well as the occurrence of absorption of some cortical bone tissue adjacent to the site of trauma. All features suggest that the injury occurred ante-mortem. In support of this hypothesis, we observed evidence of a periosteal reaction (osteoperiostitis) on the outer surface of the injury, while traces of a nonspecific infection (osteitis) are visible on the inner surface. Both evidence might be the consequence of the same injury [2,42]. Radiographic and histological analyses confirmed this interpretation and allowed us to identify the injury as an ante-mortem injury (Table 1). Another hypothetical consequence of this traumatic event was a severe displacement of the mandible, with the right condyle shifted from its natural joint point, along the zygomatic arch where it formed a new articulation (Fig. 2 f,g,h). Any evidence points to a survival of the individual to the severe injury. 3.2.

Case 2 Individual US-118 was a 3039 years old male, 162.6 3.3 cm tall. Multiple traumas of the skull and spine are detectable on his skeleton (Fig. 3). The first is a small and deep cut-mark on the right mastoid process (Fig. 3a; Table 1). Macroscopic and microscopic analyses have shown that the edges of the walls were perfectly clean and clear and there was no presence of porosity around the cut mark; the color of the kerf was brighter than the rest of the mastoid surface. Apparently, the injury occurred post-mortem. Other traumatic evidences are a series of sharp cut-marks at the level of the 10ththoracic vertebra (T-10). Among them, the most evident is on the upper-endplate, while two others are placed on the spinous process and on the right transverse process (Fig. 3b,c,d,e,f). These last two injuries, probably stab wounds, were likely inflicted simultaneously since they seem to show the same trajectory of attack, inclined by 60 with reference to the longitudinal axis of the vertebrae. This set of stab injuries shows neither porosity nor osteogenic reaction and inflammation, nor osseous regenerative process or pathological reaction, as would be expected in case of an ante-mortem trauma [6,19]. The cut marks have a V-shaped cross section with the edges of the walls inflected towards the kerf; the uniform colour of the entire area around the cut marks suggests that the injuries were inflicted when the bone was still elastic [3,4345]. The absence of bone remodeling and inflammatory reaction indicates that the individual died shortly after being stabbed (Table 1).

4. Discussion

The two case-studies presented highlight the distinction between injuries of the dry bone tissue by traditional anthropological methodologies, supplemented by radiographic and histological analyses, in order to define the timing and/or dynamics of events. The application of the new form was of considerable help in collecting the elements useful for the diagnosing of ante- vs peri-or post-mortem injuries. In case 1, the sharp force trauma inflicted was presumably a chop wound; this type of injury is produced by heavy and cutting instruments like axes, machetes, adzes and some types of swords [4]. Considering the historical period and the geographic localization, a sword or a lumberjack/farmer axe [44] are the most likely weapons. Periosteal inflammation and bone remodeling, as well as macroscopic and microscopic evidence of healing, testify that the individual survived the trauma [2]. In case 2, the cut mark on the mastoid process was probably inflicted with a sharp-edged tool during the unearthing of the skeleton, since the absence of osteogenic reactions excludes an ante-mortem event, whereas surface features, shape and color exclude a trauma occurred during the individuals lifetime. Conversely, the vertebral injuries of the same individual were probably inflicted near the individuals death by a small and sharp-edged weapon (e.g. a knife or a dagger) according to the dimensions and morphology of the injuries [44]. As the width of kerf and the groove reflect the blade dimensions of the offending weapon [13], the reduced dimensions of the injuries, especially on the posterior surface of T-10, suggest that they were due to the thin thickness of a blade. Although the margins introflexion and the elastic deformation of the bone surface typical of peri-mortem trauma are clearly visible, the complexity of this type of diagnosis on the spongy bone precludes the absolute certainty about the timing of injury. If he was stabbed in life, then he did not survive the attack. Although unlike, we cannot rule out that the peri-mortem injuries date back to a period immediately after the death of the individual, since the tissue components are the same as the living tissue (green bone) with responses indicating high elasticity and plasticity. Particular caution is required in the interpretation of this type of injuries in the forensic context. Unlike forensic pathologists who generally rely on the entire body of the victim, forensic anthropologists cannot determine always the cause of death with absolute confidence [9,38,46]. Nevertheless, providing information on skeletal injuries, along with the biological profile (sex, age, stature, ethnic origin, as well as pathological injuries and congenital skeletal anomalies) of the victim, and knowing the taphonomic conditions, a forensic anthropologist may assist the forensic pathologist in formulating hypotheses and drawing conclusions, which may contribute to [3,47] or be decisive for the resolution of a case. Therefore, as Kanetake et al. (2008) [48] pointed out, when dealing with skeletal remains, the issues raised by the judicial authority should be addressed by a team of specialists, including forensic anthropologists.

Please help to overall understand the article/case-study 1) (hypotheses, objectives, methods, key findings) and definition of key words or terms used in this case-study above.

2) A critical review of the methods employed (qualitative, quantitative, analysis, potential sources of error)

3) A discussion of how the methods or results of the case-study might be useful in a forensic or anthropological context.