A study of stab wounds

A proposal for cut marks classification using machine learning: Serrated vs. non-serrated, single vs. double-beveled knives

In tool mark identification, there is still a lack of characteristics and methodologies standardization used to analyze and describe sharp force trauma marks on skeletal remains. This study presents a classification method for cut marks on human bones, providing an applicable methodology for their examination and the relevant terminology for describing cases of sharp force trauma. A total of 350 cut marks were produced by stabbing pig ribs (Sus scrofa) with seven knives. The samples were analyzed under a stereomicroscope with a tangential light source. Through the analysis of cut marks, eleven traits were identified as significantly associated with the type of knife used. These traits included the general morphology of the kerf shape, the entrance and exit cross-profile shapes, the location of the rising on the entrance and exit cross-profile, the presence or absence of feathering, the presence or absence of shards and the location and the general morphology of the mounding. Binary logistic regression models were later trained and tested using nine out of the eleven traits. The first model categorized the cut mark as either produced by a serrated or non-serrated blade, while the second, as either produced by a single- or double-beveled blade. Classification scores of those models ranged between 63%-85% for the serration class and 63%-89% for the blade bevel class. This study proposes a new set of traits and the use of machine learning models to standardize and facilitate the analysis of stab wounds.

The 21-foot principle: Effects of age and sex on knife attack characteristics

INTRODUCTION

Knives are commonly-used weapons in criminal activities and interpersonal assaults worldwide. Injury reports have identified the upper body as the most frequent location of knife injuries, and that stabbing attacks are more fatal than slashing attacks. The first two aims of the study explore whether the type of attack and attack location could be predicted from age and sex group. The following aims compared attack times between sex and age groups and evaluated the influence of subject characteristics on attack duration. The exploratory aim surveyed subjects on attack location during the scenario if the target was not wearing body armor.

METHODS

A total of 74 subjects (male: n = 40; female: n = 34) participated. Subjects were video recorded during a 21-foot (ft) attack and participated in follow-up questions and completed a push-up test to determine physical strength. Attack time (AT), concealment location, attack type, and demographic information were correlated to age group and sex.

RESULTS

Mean AT from 21 ft was 2.40 ± 0.47 s, with the fastest of 1.75 s. The most commonly observed concealment location, attack type, and attack location on the target included the right hip (n = 62), stab (n = 62), and the chest (n = 28), respectively. After controlling for push-up ability (p < 0.05), no differences were reported between any combination of sex and age group in AT from 21 ft. Push-up ability was the sole significant predictor of AT from 21 ft (p < 0.05). Twenty-eight subjects reported they purposely avoided the body armor vest during the 21 ft attack.

CONCLUSION

Law enforcement officers are encouraged to train for quick defensive or offensive responses, such as hand-to-knife combat or rapid firearm skills that can be performed in under 1.75 s. Stronger people were predicted to complete the 21 ft attack faster.

Minimum depths to essential structures in a UK military population using computed tomography: application to stab-resistant body armour

INTRODUCTION

Edged weapons are a known domestic threat to the police forces of the UK. This threat is mitigated by wearing stab-resistant body armour that is either worn overtly or covertly depending on role. Although the UK military have traditionally focused their body armour design upon ballistic and fragmentation threats, future roles may require protection against an edged weapon threat. Since 2017, UK police body armour requirements for anatomical coverage for both edged weapon and ballistic threats are now based upon the requirements of UK military. This revised coverage may need additional research to determine minimum distances to essential structures.

METHOD

Three entry locations and penetration vectors were chosen using the limited available information in the literature, in combination with a specialist in edged weapons defence. One hundred twenty CT trauma scans of male military service personnel were subsequently analysed to ascertain minimum distances from skin surface to the first structure encountered that is included in essential coverage (heart, aorta, vena cava, liver and spleen) at 3 specific entry points.

RESULTS

Individuals ranged between 18 and 46 years, with a mean body mass index of 24.8. The absolute minimum depth from skin surface to a structure within the auspice of essential coverage was 17 mm to the liver in entry point 3 and 19 mm to the heart in entry point 2.

CONCLUSIONS

Minimum distances to critical structures were significantly larger than those described in previous studies on civilians. This study will be used to supplement existing evidence to support existing UK police requirements for stab-resistant body armour. Using the weapon entry sites and vectors described in this study, overmatching to a behind armour depth of 17 mm would cover all of this population in this study.

The nature and severity of stab wounds at tertiary care hospitals in Kingdom of Saudi Arabia

Introduction

Fights, domestic violence and street crimes are the major causes of stab wounds in the Kingdom of Saudi Arabia (KSA). The objective of the study was to describe the nature and severity of stab wounds at a tertiary care hospital in KSA.

Methods

A cross-sectional study, which included 106 patients, was conducted at the King Khalid Hospital and Prince Sultan Centre for Health Care in Al Kharj. The patients that fulfilled the inclusion criteria were recruited for the study after having confirmed their consent. The authors procured and analysed the patients' clinical notes to obtain information that was pertinent to the study. The authors recorded all data within a Microsoft Excel document. SPSS 22.0 was utilized for statistical analysis.

Results

Of 106 patients, the majority were adolescents and young adults under the age of 40 (n = 77). Eighty-seven point seven percent of patients were male and 84.0% were Saudis. Demographic details were tabulated. The top three causes were fights (20.8%) followed by domestic violence (18.9%) and street crime (17.0%). Degree of shock, stabbing zones, injury to vessels, nerves and bones, injury severity score (ISS) and Glasgow Coma Scale (GCS) were tabulated.

Conclusion

The nature and severity of stab wounds should be carefully evaluated and properly managed, as these may lead to serious complications.

The transfer of fibres via weapons from garments

Stabbings have been reported as the most frequent violent crime in countries where there is a severe restriction on obtaining firearms, such as the United Kingdom. Knives, scissors, and screwdrivers, as studied in this research, are among the most commonly encountered weapons involving stabbing events. When any of these implements are used in a stabbing, there is potential for the garment(s) worn by the victim to be damaged. In such an instance, there is an opportunity for fibres to be transferred to the weapon used, thus providing forensic evidence of proof of transfer from the victim's clothing to the weapon. This can offer valuable information in establishing what weapon was used to harm the victim through linking fibres from the victim's garment(s) to a weapon recovered from a suspect. This research simulates vertical stabbings - performed by a human participant - in to a polystyrene block supporting the clothing (essentially acting as the victim's torso), to reflect an authentic scenario. The aforementioned weapons were used along with 3 varieties of garments (cotton, polyester and a linen/viscose mix) offering different characteristics of shedability and structure for the simulated stabbings. Low power microscopy was utilised to view the transferred fibres. The amount of fibres transferred on to the implement were recorded for each repeat. 2279 individual fibres were found over 10 repeats from the knife in relation to the linen/viscose garment. This was the highest amount of transference found with the lowest number attributed to the screwdriver-polyester relationship, providing 320 recorded fibres over 10 repeats. The findings of this study suggest that the number of fibres transferred is not only related to the shedability of the garment but also the surface area characteristics of the receiving weapon and the ability for the garment to tear.

Assaults in South East London

A survey was performed of 425 consecutive patients attending Lewisham Hospital as a result of deliberate physical violence. Eighty-two per cent attended ‘out of hours’, and in at least 50% alcohol was a contributing factor. Less than half the incidents were reported to the police. Fifteen per cent of the attacks were due to knives and accounted for 47% of the admissions and 90% of the serious injuries. The results support the view that it is becoming common for youths to be armed. Assault victims, particularly those with knife wounds place a considerable burden on hospital resources. Accident and Emergency departments are ideal places to monitor the epidemiology of assaults.

Homicide-Suicide by Stabbing Study Over 10 Years in the Toulouse Region

The authors conducted a retrospective study of 70 cases of homicide and suicide in the Toulouse region to identify the variables that enable us to determine whether a death is a homicide or a suicide. This work showed that the following characteristics-a female victim, numerous wounds, and the presence of 1 or more vertical chest wounds-suggest homicide. It also highlights the importance of inspecting clothing, in particular the position of clothing and the presence or absence of slashes.

Assault patients attending a Scottish accident and emergency department

Over 2 months in 1995, 235 assault patients attended the accident and emergency department of the Royal Alexandra Hospital, Paisley (2.4% of total new attendances). 80% were male and their mean age was 28 years (range 6-64); men were the assailants in over 90% of attacks. Alcohol had been consumed by 69% of the victims and 9% admitted to taking illicit drugs. The commonest place of assault was the street (44%) but women were more likely to be assaulted in their homes. Penetrating weapons were used in 23% of assaults. 60% of all injuries were to the head and neck. 27% of the victims were admitted to hospital. Paisley has an assault rate similar to that of other UK centres but the use of penetrating weapons is much higher than elsewhere.

Intracardiac therapy following emergency thoracotomy in the accident and emergency department: an experimental model

For a select group of patients with penetrating chest trauma, immediate thoracotomy in the accident and emergency department offers the only chance of survival. Foley catheters have been used to achieve haemostasis in cardiac wounds but are not widely used for intracardiac fluid and drug administration during resuscitation. In an anatomical model designed to assess this procedure an average flow rate of 275 ml min-1 was achieved. The equipment required is readily available and easily assembled.

Stab wound of the neck: potential pitfalls in management

The authors describe the case history of a patient who was stabbed in the back of his neck with a knife and who later presented with a Brown-Séquard syndrome attributable to cervical spinal cord damage. Myelography and CT revealed a compressive extradural lesion shown at exploratory operation to be a loculus of cerebrospinal fluid (CSF). The loculus had formed as a consequence of leakage of CSF through a dural tear caused by the knife. Evacuation of this loculus resulted in some neurological improvement. The necessity of obtaining a clear history and of performing a thorough clinical examination is explained. The need to admit patients in whom stab wounds of the neck have transgressed subcutaneous fat is reiterated. Early referral to a neurosurgeon is advised for those patients with neurological deficits.

Preventability of death from penetrating injury in England and Wales

A total of 1000 deaths from injury in England and Wales have been reviewed to establish the incidence and pattern of penetrating injury and the adequacy of its management. Of the 1000 deaths, 71 (7.1 per cent) were due to penetrating injury. There were 32 knife wounds and 30 firearm injuries. Most of the latter were suicides. Only 17 patients (24 per cent) reached hospital alive. Of these cases, 10 had extracranial injury and all 10 deaths were considered to have been potentially preventable when reviewed by four external assessors. One of seven patients with cranial injury was considered to have been a potentially preventable death. The median age of the 11 cases of potentially preventable death was 37 years (range: 7-61 years). Of these, three did not have any surgery for surgically treatable injuries. Seven patients underwent operation and difficulty was encountered in six of these. It appears from our figures that whilst penetrating injury is an uncommon cause of death, it is poorly managed. The implications of this finding for systems of injury care in the United Kingdom are discussed.