Gunshot-related transport of micro-organisms from the skin of the entrance region into the bullet path

Low energy gunshot injuries: Does removal of retained bullet fragmentation at the time of internal fixation reduce the risk of fracture related infection?

OBJECTIVE

To examine the effects of RBF (Retained Bullet Fragment) removal at the time of long bone fixation on FRI (fracture related infection) rates in low energy GSI (Gunshot Injury) related fractures.

DESIGN

Retrospective Cohort Study SETTING: Level 1 Academic Trauma Center INTERVENTION: Retrospective review of the impact of RBFs on the risk of FRI when employing internal fixation in low energy GSI (Gunshot Injury) related fractures. In situations where the injury pattern requires surgical fixation, the question arises as to whether or not the RBFs need to be removed to prevent FRI.

MAIN OUTCOME MEASURES

Whether or not the RBFs removed in our patient population prevented short- and long-term fracture related infection after low-energy gunshot injury (FRI-LGI).

RESULTS

Of the 2,136 GSI related fractures, 131 patients met inclusion criteria, 81 patients underwent removal (R) of RBFs at the time of internal fixation while 50 patients did not undergo any removal (NR) at time of internal fixation. Among the patients who underwent surgical intervention, (Open Reduction Internal Fixation) ORIF was performed in 55 cases (R: 39; NR: 16), and (Intramedullary Nail) IMN was performed in 76 cases (R: 42; NR: 34). The overall rate of deep FRI-LGI was 6.9 % of the 131-patient cohort. We found that removal of RBFs had a statistically significant impact on the rate of deep FRI-LGI when compared to the NR group (p = 0.031). In the RBF removal group, only two patients (2.4 %) developed deep FRI-LGIs, whereas in the NR group, seven patients (14.0 %) developed deep FRI-LGIs. The incidence of early FRI-LGI was higher in the NR group (median 0.6 months) compared to the R group, which was associated with late FRI-LGIs (median 10.1 months) when they occurred.

DISCUSSION

In our study population, we found a statistically significantly increased incidence of deep and early FRI-LGI when RBFs are not removed at the time of extra-articular long bone internal fixation. The presence of retained bullet fragments following internal fixation may pose a risk factor for future development of deep FRI-LGI. We believe a surgeon should use their best judgment as to whether a RBF can safely be removed at the time of long bone fixation. Based on our findings, if safely permitted, RBF removal should be considered at the time of GSI long bone fixation resulting from low energy hand gun injuries.

Gunshot residues found at the exit wound: a case report

Gunshot residues (GSRs) play an important role in forensic investigations of gun-related violence. The presence of GSRs has been described to help to identify the bullet entry area, as it was supposed not to be found at exit wounds. This report details the suicidal headshot of an 84-year-old male where unburned tube-like, cuboid and flake-formed powder particles have been found not only at the inside of the muzzle but also circular around the exit wound. With very short-barrelled weapons, it must be expected that part of the propellant charge leaves the barrel unburned behind the bullet. In contrast to that, the barrel length of the used weapon should lead to a complete burn-up of powder particles. The surprisingly large number of unburned powder particles present at the exit wound of the injury gave reason for further investigation to understand the underlying ballistic aspects and outlines the importance of having a close look at incidence scene photos during an investigation.

Gunshot Wounds: Ballistics, Pathology, and Treatment Recommendations, with a Focus on Retained Bullets

As the epidemic of gunshot injuries and firearm fatalities continues to proliferate in the United States, knowledge regarding gunshot wound (GSW) injury and management is increasingly relevant to health-care providers. Unfortunately, existing guidelines are largely outdated, written in a time that high-velocity weapons and deforming bullets were chiefly restricted to military use. Advances in firearm technology and increased accessibility of military grade firearms to civilians has exacerbated the nature of domestic GSW injury and complicated clinical decision-making, as these weapons are associated with increased tissue damage and often result in retained bullets. Currently, there is a lack of literature addressing recent advances in the field of projectile-related trauma, specifically injuries with retained bullets. This review aims to aggregate the available yet dispersed findings regarding ballistics, GSW etiology, and treatment, particularly for cases involving retained projectiles.

Differing sizes of bullet entrance holes in skin of the anterior and posterior trunk

The aim of the present study was to establish whether the size (diameter and area) of bullet entrance holes in skin varies between distant shots to the anterior and posterior trunk, respectively, when using the same ammunition (in concreto pistol cartridges 9 mm Luger). For that purpose, specimens of porcine skin from the belly region and the back were taken (10 samples each) and shot at from a distance of 1.6 m. The entrance holes were photo-documented under standardised conditions. After image processing for contrast enhancement, the maximum diameter and the area of each skin defect were measured automatically by means of an image analysis system. Both size parameters differed significantly depending on the body region affected. On the back with its comparatively thick dermis, the skin defects were considerably smaller than those on the ventral trunk where the corium is less thick. This difference can be explained by the fact that the elastic properties of skin are strongly determined by the connective tissue which is especially rich in fibres. The study results were consistent with the authors’ casework experience and support the assumption that the entrance site of gunshot wounds has a major influence on the size of the bullet hole in skin.

Factors affecting use of ballistics gelatin in laboratory studies of bacterial contamination in projectile wounds

BACKGROUND

Ballistics gelatin is a common tissue surrogate used in bacterial contamination models for projectile wounds. Although these studies have demonstrated that bacteria are transferred from the surface of the gelatin to the wound track by a projectile, quantifiable results have been inconsistent and not repeatable in successive tests.

METHODS

In this study, five areas of a typical contamination model in which bacterial recovery or survival are affected were identified for optimization. The first was a contaminated "skin" surrogate, where the novel use of vacuum filtration of a bacterial culture and buffer onto filter paper was employed. The other possibly problematic areas of the bacterial distribution model included the determination of bacterial survival when the contamination model is dried, survival in solid and molten gelatin, and the effect of high-intensity lights used for recording high-speed video.

RESULTS

Vacuum filtration of bacteria and buffer resulted in a consistent bacterial distribution and recovery. The use of phosphate buffer M9 (pH 7) aided in neutralizing the ballistics gelatin and improving bacterial survival in solid gelatin. Additionally, the use of high-intensity lights to record high-speed video and the use of a 42^°C water bath to melt the gelatin were found to be bactericidal for gram-positive and gram-negative bacteria.

CONCLUSIONS

Multiple areas of a typical contamination model in which bacterial survival may be impeded were identified, and methods were proposed to improve survival in each area. These methods may be used to optimize the results of bacterial contamination models for medical applications, such as understanding the progression of infection in penetrating wounds and to identify possible sources of contamination for forensic purposes.

Wound morphology in contact shots from blank cartridge handguns: a study on composite models

It is a well-known fact that blank cartridge guns can cause penetrating and even fatal injuries when discharged in contact or at very close ranges. In these cases, the gas jet perforates the skin leaving an entrance wound similar to that from a conventional gun. In order to investigate the wound morphology in contact shots from blank firearms, test shots were fired at composite models of pig skin and gelatin blocks using three different calibre 9-mm blank cartridge handguns (two pistols and one revolver) and two types of ammunition. It turned out that the penetrating gas jet produced roundish skin defects resembling bullet entrance holes. Small skin particles from the perforation site were dispersed in the underlying simulant where radiating cracks containing greyish gunshot residues indicated the original expansion of the inrushing combustion gases. Apart from the size of the permanent entrance hole in the skin and the final position of the displaced tissue particles, the penetration depth of the gas jet was determined. Under the specified conditions of the test shots, the zone of mechanical destruction within the simulant was 2.2 to 6.1 cm in length, which illustrates the injuring potential of contact shots inflicted with blank cartridge handguns.

Wound ballistics of firearm-related injuries--part 1: missile characteristics and mechanisms of soft tissue wounding

Firearm-related injuries are caused by a wide variety of weapons and projectiles. The kinetic energy of the penetrating projectile defines its ability to disrupt and displace tissue, whereas the actual tissue damage is determined by the mode of energy release during the projectile-tissue interaction and the particular characteristics of the tissues and organs involved. Certain projectile factors, namely shape, construction, and stability, greatly influence the rate of energy transfer to the tissues along the wound track. Two zones of tissue damage can be identified, the permanent cavity created by the passage of the bullet and a potential area of contused tissue surrounding it, produced mainly by temporary cavitation which is a manifestation of effective high-energy transfer to tissue. Due to the complex nature of these injuries, wound assessment and the type and extent of treatment required should be based on an understanding of the various mechanisms contributing to tissue damage.

Lower genitourinary trauma in modern warfare: the experience from civil violence in Iraq

BACKGROUND

Reports on genitourinary (GU) trauma during the Iraqi conflict have been limited to battlefield injuries. We sought to characterise the incidence, mechanism of injury, wounding pattern, and management of lower GU injuries sustained in civil violence during the Iraqi war.

PATIENTS AND METHODS

A total of 2800 casualties with penetrating trauma to the abdomen and pelvis were treated at the Yarmouk Hospital, Baghdad from January 2004 to June 2008. Of the casualties 504 (18%) had GU trauma including 217 (43%) with one or more injuries to the lower GU organs.

RESULTS

Among the 217 patients there were 262 lower GU injuries involving the bladder in 128 (48.8%) patients, bulbo-prostatic urethra in 21 (8%), penis in 24 (9.2%), and scrotum in 89 (34%). Injuries to the anterior urethra and genitals were inflicted by Improvised Explosive Devices (IEDs) in 53-67% of cases and by individual firearms in 33-47%, while injuries to the posterior urethra and bladder were inflicted by IEDs in 17-22% of cases and by firearms in 78-83%. All penile wounds were repaired save 3 (12.5%) patients who underwent total penectomy. Of 63 injured testicles 54 (86%) could be salvaged and 9 (14%) required unilateral orchiectomy. The leading cause of death was an associated injury to major blood vessels in 26 (84%) of 31 patients who died.

CONCLUSIONS

Injuries to the anterior urethra and genitals were commonly caused by IEDs, while injuries to the posterior urethra and bladder were usually caused by individual firearms. Testis injury was almost always salvageable. Associated trauma to major blood vessels was the leading cause of death in these casualties.

Urethral and penile war injuries: The experience from civil violence in Iraq

Objective

To determine the incidence, mechanism of injury, wounding pattern and surgical management of urethral and penile injuries sustained in civil violence during the Iraq war.

Patients and methods

In all, 2800 casualties with penetrating trauma to the abdomen and pelvis were received at the Al-Yarmouk Hospital, Baghdad, from January 2004 to June 2008. Of these casualties 504 (18%) had genitourinary trauma, including 45 (8.9%) with urethral and/or penile injuries.

Results

Of 45 patients, 29 (64%) were civilians and 16 (36%) were Iraqi military personnel. The injury was caused by an improvised explosive device (IED) in 25 (56%) patients and by individual firearms in 20 (44%). Of the patients, 24 had penile injuries, 15 had an injury to the bulbar urethra and six had an injury to the posterior urethra. Anterior urethral injuries were managed by primary repair, while posterior urethral injuries were managed by primary realignment in five patients and by a suprapubic cystostomy alone in one. An associated injury to major blood vessels was the cause of death in eight of nine patients who died soon after surgery (P < 0.001).

Conclusion

Urethral and penile injuries were caused by IEDs and individual firearms with a similar frequency. Most of the casualties were civilians and a minority were military personnel. Injuries to the anterior urethra can be managed by primary repair, while injuries to the posterior urethra can be managed by primary realignment. An associated trauma to major blood vessels was the leading cause of death in these casualties.

GSR deposition along the bullet path in contact shots to composite models

In contact shots, all the materials emerging from the muzzle (combustion gases, soot, powder grains, and metals from the primer) will be driven into the depth of the entrance wound and the following sections of the bullet track. The so-called "pocket" ("powder cavity") under the skin containing soot and gunpowder particles is regarded as a significant indicator of a contact entrance wound since one would expect that the quantity of GSR deposited along the bullet's path rapidly declines towards the exit hole. Nevertheless, experience has shown that soot, powder particles, and carboxyhemoglobin may be found not only in the initial part of the wound channel, but also far away from the entrance and even at the exit. In order to investigate the propagation of GSRs under standardized conditions, contact test shots were fired against composite models of pig skin and 25-cm-long gelatin blocks using 9-mm Luger pistol cartridges with two different primers (Sinoxid® and Sintox®). Subsequently, 1-cm-thick layers of the gelatin blocks were examined as to their primer element contents (lead, barium, and antimony as discharge residues of Sinoxid® as well as zinc and titanium from Sintox®) by means of X-ray fluorescence spectroscopy. As expected, the highest element concentrations were found in the initial parts of the bullet tracks, but also the distal sections contained detectable amounts of the respective primer elements. The same was true for amorphous soot and unburned/partly burned powder particles, which could be demonstrated even at the exit site. With the help of a high-speed motion camera it was shown that for a short time the temporary cavitation extends from the entrance to the exit thus facilitating the unlimited spread of discharge residues along the whole bullet path.

Experimental simulation of reentry shots using a skin-gelatine composite model

A bullet that has passed in and out of one body segment may continue its way into another part of the body causing a second entrance ("reentry") wound, which is often said to have an atypical and sometimes confusing appearance. To analyze this problem in a systematical approach, 9-mm Parabellum full metal-jacketed projectiles were fired at skin-gelatine composite models simulating the consecutive passage of a bullet through two parts of a body. When there was a distance between the two segments, the primary exit and the reentry skin wounds did not show any distinctive features differing from usual gunshot injuries. In the case of contact between exit and reentry site, the corresponding skin wounds resembled each other as both had central tissue defects surrounded by abrasion areas. The subsequent investigation of the simulant revealed that skin particles from both the exit and the adjacent reentry site had been displaced in the direction of the shot along the whole bullet track of the second segment. The morphological findings are presented and discussed with respect to the pertinent literature, and possible physical ballistic explanations are suggested.

Effect of shortening the barrel in contact shots from rifles and shotguns

In a suicidal gunshot fired to the chest from a carbine, the barrel of which had been shortened to half its original length, an unexpectedly large degree of destruction of the anterior thoracic wall with extensive undermining of the subcutis was found. This phenomenon was investigated for reconstructive purposes by firing test shots from two different long guns (caliber 7.92 x 57 repeating rifle with full-jacketed pointed bullet and caliber 12/70 single-barreled shotgun with shotgun slug) into blocks of soap (38 x 25 x 25 cm). The contact shots were fired before and after shortening the barrels (repeating rifle from 60 to 30 cm and single-barreled shotgun from 72 to 36 cm). The volume of the cavities in the simulant was visualized three-dimensionally with the help of a multislice computed tomography (CT) scanner and calculated sectionally. With the repeating rifle and the single-barreled shotgun, the shots from the sawed-off barrels produced significantly larger cavity diameters in the first section of the bullet track. This effect is attributable to the fact that, with a shortened barrel, the gas pressure at the muzzle is higher, thus, leading to increased expansion in the initial part of the wound track in contact shots.

Gunshot-related displacement of skin particles and bacteria from the exit region back into the bullet path

In previous studies, it was shown that there is a gunshot-related transport of skin particles and microorganisms from the entrance region into the depth of the bullet path. The present study deals with the question of whether gunshots may also cause a retrograde transport of skin particles and microorganisms from the bullet exit region back into the bullet path. For this purpose, we used a composite model consisting of rectangular gelatin blocks and pig skin. The skin pieces were firmly attached to the gelatin blocks on the side where the bullet was to exit. Prior to the test shots, the outer surface of the pig skin was contaminated with a thin layer of a defined bacterial suspension. After drying the skin, test shots were fired from a distance of 10 m using cartridges calibre .38 spec. with different bullet types. Subsequent analyses showed that in all shots with full penetration of the composite model, the bullet path contained displaced skin particles and microorganisms from the skin surface at the exit site. These could be regularly detected in the distal 6-8 cm of the track, occasionally up to a distance of 18 cm from the exit hole. The distribution of skin particles and microorganisms is presented and the possible mechanism of this retrograde transport is discussed.