Bone beveling caused by blunt trauma: a case report

A scanning electron microscopy study of projectile entry fractures in cortical bone; genesis and microarchitectural features

The present paper presents a scanning electron microscope (SEM) analysis of the genesis and microarchitecture of experimentally induced cortical entry fractures in porcine scapulae impacted at velocities ranging from 54 to 897 m/s. SEM observation was conducted on polyurethane replicas cast from negative silicone moulds. Analysis of the sequence of fracture processes operative during projectile impact revealed the presence of ring cracks at the site of impact, confirming that penetration in sandwich bones is achieved by cone crack propagation. Despite impulsive loading, two forms of plastic deformation were identified in the cortical bone surrounding the entry fracture up to a maximum velocity of 871 m/s. Microscopic radial and concentric cracks were associated with projectile impact, and the role of pores and pits as stress concentrators was captured. Possible underlying mechanisms for the observed plastic deformation are described, and the diagnostic utility of SEM analysis is presented.

Beach and patio umbrella injuries treated at emergency departments

INTRODUCTION

Beach and patio umbrellas may cause injury. There is limited published information on injuries due to beach and patio umbrellas. This study sought to describe beach and patio umbrella injuries reported to United States emergency departments (EDs).

METHOD

An analysis was performed of beach and patio umbrella injuries using data from the National Electronic Injury Surveillance System during 2000-2019.

RESULTS

An estimated 5,512 beach umbrella injuries and 7,379 patio umbrella injuries were identified. The patient was age 40 years or older in 62.1% of the beach umbrella and 65.1% of the patio umbrella injuries. The patient was female in 68.0% of the beach umbrella and 66.9% of the patio umbrella injuries. Wind was reported involved in 50.6% of the beach umbrella and 27.5% of the patio umbrella injuries. The most frequently reported injuries with beach and patio umbrella injuries, respectively, were laceration (44.0% vs 33.0%), contusions or abrasions (19.8% vs 19.0%), and internal organ injury (16.6% vs 17.0%) and most often affected the head/neck (60.2% vs 44.0%) and upper extremity (16.3% vs 30.1%).

CONCLUSIONS

The majority of patients with beach and patio umbrella injuries treated at EDs were age 40 years or older and most patients were female. For both types of umbrella injury, the most frequently reported injury was laceration followed by contusions or abrasions and internal organ injury, and the body part with the highest proportion of injuries was the head/neck followed by the upper extremity. Practical Applications: Persons should use sturdier models of beach or patio umbrella, use a rocking motion to dig into the sand and secure the beach umbrella with a metal anchor and screws, add weight to the bottom of the umbrella, and tilt the umbrella into the wind. Policy-makers should educate the public about the potential dangers of beach and patio umbrellas.

Nail Gun Suicide: An Atypical Case Report and Review of the Literature

ABSTRACT

Nail guns are pneumatically driven or powder-actuated tools, which are used to drive nails into wood or concrete. A 42-year-old man, who was a builder by profession and history of antidepressant use, was found dead in his vehicle, holding a "Ramset" nail gun in his right hand. A straight metal nail and a book with a small hole were recovered from the scene.At autopsy, an irregularly circular puncture wound was seen on the forehead and a cruciate laceration was seen on the posterior aspect of the scalp. No burning, blackening, or tattooing was present around either injury. Both internal and external beveling was present with the latter being relatively larger. Toxicological analysis revealed alcohol and methamphetamine in blood. Psychiatric history and substance abuse must also be considered when individuals in construction industry are given access to tools like nail guns.Several unique features not previously reported were observed in this case. The deceased had overcome the built-in safety mechanism of the nail gun, by placing a book in between his forehead and muzzle. Another unique feature is that the nail had exited the cranium. Beveling, a feature commonly found in firearm injuries, was also seen in this case.

Interpol review of shoe and tool marks 2016-2019

This review paper covers the forensic-relevant literature in shoe and tool mark examination from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Crack propagation through sandwich bones due to low-velocity projectile impact

Projectile impact in sandwich bones typically results in formation of conoidal wounds exhibiting a larger region of damage on the inner cortical plate termed the bevel. To date, a number of hypotheses have been put forward to explain the formation of this wound type. The plug and spall hypothesis suggests that the conoidal morphology is produced by a two-phase mechanism of shear plug formation followed by internal bevel production during projectile exit. In contrast, the cone crack hypothesis suggests that such wounds are produced by cone crack propagation through the three laminae of the sandwich bone, resulting in the formation of bioceramic conoids consisting of all three bone laminae. In order to test these hypotheses, 28 non-human sandwich bones were impacted with 6-mm carbon steel spheres at velocities ranging from 26 to 96 metres per second (m/s). Impacts were filmed utilizing high-speed videography and fracture morphology analysed using micro-computerized tomography (μ-CT). Sequential increase in velocity successfully captured the genesis of conoidal wounds. Low-velocity impact produced circular depressed fractures in the outer cortex exhibiting angulated cortical fracture edges. An increase in velocity resulted in translaminar fracture and production of one intact and three fragmentary bioceramic conoids. At the highest velocities, conoids were fragmented and lost in the ejecta plume, with attached fragments undergoing dynamic movement during and after perforation. Significantly, projectile exit was not required for bevel production. The implications of these findings in wound interpretation are discussed.

A novel hypothesis for the formation of conoidal projectile wounds in sandwich bones

When perforated by a projectile, sandwich bones typically exhibit wounds with a distinct conoidal morphology that is widely utilised both in wound diagnosis and trajectory determinations. However, the dynamic fracture mechanisms underlying this intriguing wound type have yet to be experimentally verified. The most frequently quoted hypothesis for their formation, plug and spall, is difficult to reconcile with the conoidal morphology exhibited by such wounds. The present article carries out a high-speed videographic and micro-computerised tomographic (μ-CT) analysis of perpendicularly produced projectile wounds induced from 139.15 to 896.84 metres per second (m/s) in pig scapulae. Fundamental data on energy absorption, wound shape and bevel symmetry are presented. Cross-sectional fracture morphology revealed by μ-CT raises the novel hypothesis that tensile stresses induced by the projectile in the outer cortex elicit cone crack formation and that this cone crack then propagates catastrophically through the entire sandwich structure. This process results in the momentary formation of a bioceramic conoid, a conoidal volume of bone consisting of all three sandwich bone layers separated from the parent bone by the internal bevel. Fragmentation of the separated volume leaves the conoidal wound behind as its counterpart. The significance of this hypothesis in terms of differential diagnosis and interpretation of bevel shape is discussed.

Fatal Chest Injury Caused by Windblown Beach Umbrella

We present the case of a windblown beach umbrella inflicting fatal penetrating blunt force to the chest of a 55-year-old female beachgoer. A postmortem examination and detailed case history review were performed which revealed left ventricular trauma, determined to be the cause of death. Using recorded wind speeds from the date of the incident and the weight of the umbrella, we were able to calculate the pressure with which the umbrella struck the victim to be 16,000 PSI. Witness reports, medical records, scene details, and examination of a rental beach umbrella allowed the forensic pathologist to conclude that the object causing this woman's death was a windblown beach umbrella.