The characteristics of the pressure waves generated in the soft target by impact and its contribution to indirect bone fractures

Gunshot trauma in human long bones: towards practical diagnostic guidance for forensic anthropologists

In contrast to cranial gunshot trauma, diagnosis and interpretation of gunshot trauma to long bones remains difficult and controversial. The aim of this study is to review the published literature on fracture patterns resulting from gunshot trauma in human long bones, and to use the described characteristics to provide practical guidance for the forensic anthropologist. In order to achieve this, medical and forensic publications on this topic were reviewed. Several types of fractures, such as linear, oblique, comminuted and butterfly fractures, have been observed in either the shaft or the ends of long bones. Indirect fractures that are not caused by bullets striking bone directly but by bullet-induced forces to the surrounding soft tissue have been found as well. Some of these fractures are related to a specific context or mechanism which might help in the forensic reconstruction of events. It is recommended that future research should focus on available medical data to provide more detailed descriptions on fracture patterns for forensic purposes. Experimentation with bone surrogates and computer modelling might also provide better and more realistic reconstructions of gunshot trauma in the future and provide valuable insights for its diagnosis and interpretation in forensic anthropology.

A comparison of the incidence of concomitant ipsilateral femoral neck fractures in ballistic versus blunt femur fractures

OBJECTIVE

The purpose of this study is to evaluate the rate of ipsilateral femoral neck fractures in ballistic femur fractures and compare this to similar non-ballistic blunt fractures.

DESIGN AND SETTING

A retrospective review of an institutional trauma database was completed at a single Level 1 trauma academic medical center.

PATIENTS

All patients treated for a ballistic or blunt femur fracture presenting to our institution between May 1, 2018, and February 29, 2020, were included. In all, 270 femur fractures were identified. We excluded 73, including 29 pediatric fractures and 44 geriatric peritrochanteric fractures. The final cohort included 197 femur fractures in 187 patients. Of the 197 femur fractures included, 68 were ballistic and 129 were blunt mechanism.

RESULTS

Four ipsilateral femoral neck fractures were identified in the ballistic fracture cohort. There was no significant difference between ipsilateral femoral neck fractures associated with blunt femur fractures when compared with ballistic fractures, 7.7 versus 5.8%, respectively. We identified one occult femoral neck fracture that was associated with a ballistic 32-B3 femoral shaft fracture. The ipsilateral femoral neck fracture associated with the 32-B3 ballistic femoral shaft fracture was not identified on plain films (Fig. 3A, B) and review of CTA during initial trauma workup. Identification of this fracture intra-operatively changed the treatment plan from standard proximal locking to recon proximal locking for this case. Patients included in the blunt fracture cohort were more likely to be poly-trauma patients with a higher rate of associated fractures.

CONCLUSIONS

We detected no difference in rate of associated femoral neck fracture between blunt and ballistic femur fractures. These fractures can be missed on initial evaluation, which may lead to a delayed diagnosis and alter treatment plans. The authors conclude that treating surgeons must remain vigilant with a high index of suspicion for occult femoral neck fractures in patients who suffer ballistic femoral shaft fractures. Low-energy ballistic injuries should not rule out the possibility of an occult femoral neck fracture.

Clothing increases the risk of indirect ballistic fractures

BACKGROUND

Current literature has shown the mechanism of how indirect fractures occur but has not determined what factors increase the risks of such fractures. The objective of this study is thus to determine the effect of clothing and soft tissue thickness on the risk of indirect fracture formation.

METHODS

Twenty-five fresh red deer femora embedded in ballistic gelatine were shot with varying distances off their medial cortex with a 5.56 × 45 mm North Atlantic Treaty Organization (NATO) bullet while being filmed with a slow-motion video. We compared the effect of two different gelatine depths and the effect of denim cloth laid onto the impact surface of the moulds.

RESULTS

Bullet passage in thinner moulds failed to cause fracture because the bullet exited the mould before a large expanding temporary cavity was produced. Clothing dramatically altered the size and depth of the expanding cavity, as well as increased lateral pressures, resulting in more severe fractures with greater bullet distances from the bone that can cause fracture.

CONCLUSIONS

Clothing increases the risk of indirect fracture and results in larger, more superficial temporary cavities, with greater lateral pressures than are seen in unclothed specimens, resulting in more comminuted fractures. Greater tissue depth affords the 5.56 × 45 mm NATO a chance to yaw and thus develop an enlarging temporary cavity that is sufficient to cause fracture.

Determining the wounding effects of ballistic projectiles to inform future injury models: a systematic review

INTRODUCTION

Penetrating wounds from explosively propelled fragments and bullets are the most common causes of combat injury experienced by UK service personnel on current operations. There is a requirement for injury models capable of simulating such a threat in order to optimise body armour design.

METHOD

A systematic review of the open literature was undertaken using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses methodology. Original papers describing the injurious effects of projectiles on skin, bone, muscle, large vessels and nerves were identified.

RESULTS

Projectiles injure these tissues by producing a permanent wound tract (PWT), comprised of a central permanent wound cavity, in conjunction with a zone of irreversible macroscopic tissue damage laterally. The primary mechanism of injury was the crushing and cutting effect of the presented surface of the projectile, with an additional smaller component due to macroscopic damage produced by the radial tissue displacement from the temporary tissue cavity (TTC). No conclusive evidence could be found for permanent pathological effects produced by the pressure wave or that any microscopic tissue changes due to the TTC (in the absence of visible macroscopic damage) led to permanent injury.

DISCUSSION

Injury models should use the PWT to delineate the area of damage to tissues from penetrating ballistic projectiles. The PWT, or its individual components, will require quantification in terms of the amount of damage produced by different projectiles penetrating these tissues. There is a lack of information qualifying the injurious effect of the temporary cavity, particularly in relation to that caused by explosive fragments, and future models should introduce modularity to potentially enable incorporation of these mechanisms at a later date were they found to be significant.

Management of low-caliber, low-velocity gunshot wounds of the maxillofacial region

Low-velocity, low-caliber missile wounds have a wounding profile different from that of high-velocity, high-caliber missiles. The pathophysiology of these types of injuries is discussed. Care for such injuries should be conservative.