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We're going to talk about ballistic trauma. I'm going to review a conceptual approach to managing these challenging injuries and how we assess them and approach them to illustrate this. I'm going to look at a question of how historically our approach to these injuries has developed and evolved, looking specifically whether or not uh recent years we've become too aggressive with our surgical treatment of these injuries. In order to understand that I'm going to look at the pathology of what goes on in the wound after the interactions between high levels of kinetic energy and biological tissue. And finally, we're gonna review the current approach to treating gunshot wounds to introduce myself. My name is Joanne Pen Bala. I'm an orthopedic trauma surgeon with a pure trauma practice currently working in the Oxford Trauma Service. I've got research interesting infection, ballistic injuries and outcomes after severe limb injury. I'm speaking entirely on my own behalf and not that of Oxford, the Royal Navy, the British government or any other organization I'm affiliated to the images used throughout this are used with the express consent of the patient's involved. So let's start off with where we are the phenomenal International Committee of the Red Cross War Surgical Manual is a fantastic resource and I would certainly commend it to anyone but it takes quite a severe attitude. Two gunshot wounds and suggest radical debridement of all military gunshot wounds should be the standard of care. I would like to look into the basis for that and maybe suggest that we can stratify and be a little bit more measured with our consideration of treating these injuries. So a quick review, the kinetic energy of a bullet is, as we know from our high school physics is equal to the mass times velocity squared halved. So let's look at the two most basic divisions of weapons system. So we have a modern battlefield assault rifle here. We have the A K 12 and the marker of pistols. So in broad terms, we can divide firearms into rifles which typically have higher energy bullets and pistols or handguns which have lower energy bullets. But again, we're surgeons, we don't treat weapon systems. We treat the injuries. We see, let's look at this in a bit more detail. So the kinetic energy that around has when it approaches on the lateral side of this limb, some of that the kinetic energy is transferred into the tissue and a small amount of kinetic energy is left in the round as it passes out of the body. The difference in the kinetic energy is the amount of kinetic energy that has been transferred into the wound and critically, the greater the amount of energy transfer than the more severe, complicated or worse the wound will be. And that's a very fundamental concept to understand the amount of kinetic energy and the rate at which has been dumped into the body tissues relates closely to the complexity and severity of the wound were likely to have to treat. So how can we assess this? Well, if you've got a smartphone, you want to use a Q R code reader, you can get the paper that underlines the next series of slides available on the left that was published an injury a few years ago. So the first thing to do is say that if a wound is obviously complex, it is complex. It's a tautology, but it's a very accurate one. If it looks like a bad wound, it is a bad wound treated like a bad wound. I'll also include in that any wounds that involve a neuro vascular injury. So if you got an a vascular tissue distal to the wound, or if you've got a neurological compromise, distal to the wound, most surgeons would agree that that necessitates surgical expiration and treatment. So having made that very clear caveat, how do we quantify or qualify wounds that have none of that obvious high energy features? So the first thing I'd say is um if there's a fracture, so if the, if a bullet has hit bone tissue, there's a huge density bone tissues, there's likely a significant amount of energy transfer. And in the paper, we found the association between fractures and a requirement for repeat the bribe mint if the bullets have been retained. So if a bullet leaves the body, it still possesses some kinetic energy. If it remains in the body, all of the kinetic energy it possessed has been transferred into the tissue. And so that's a surrogate marker of a complex wound And finally fragmentation. If the bullets fragmented, it will likely create a greater area of damage. And we'll look at why that is um in the next few slides. But these are all things, the possession of a fracture, retention of bullets and the fragmentation that can assess on a simple single plain X ray radiograph. So it's a very rapid way that one can assess the degree of energy transfer, likely wound severity. And the key thing here is to treat the energy transfer, not the weapon system. And also stress that is very good evidence primarily for the United States that not all gunshot wounds do in fact need surgery. Lots of case series of very low energy transfer injuries that have been treated with conservative measures. So as a as an example of this, I've got two sets of injuries and the approximate weapon system is not the exact weapon systems they were caused by. So firstly, we've got this calcaneal fracture that was caused by a high energy A K type weapon system. And we can see here that there's been, although it's transverse through bone tissue, it's the, the very cancellous component of the calcaneal bone and has been actually very little transfer. You can see the two wounds, I don't know which one's entry. I don't know which one's exit. But you can see that despite the high energy transfer, the high energy weapon system, it's a low energy transfer wound conversely on the forearm radiograph, you can see a highly fragmented fracture to the ulna bone. And you can see that the bullet itself is fragmented as well. So even though this was a relatively low energy handgun weapon that caused this wound, it's been a high energy transfer and a very complex wound lightly with a significant amount of tissue destruction that definitely requires surgical treatment. So let's look at this question of, are we treating these? So the war surgical manual from the I C R C is only one of a number of textbooks that really recommend a quite a aggressive treatment of battlefield gunshot winds, particularly encouraging people to lay open or gunshot wind tracks if we go back even further than these again, very fine textbooks. But if we go back further to a British army surgeon who was a junior surgeon in the first World War and a senior surgeon, the second World War. So a vast amount of experience of surgically treating gunshot wounds, the majority of which experience he accrued prior to the onset of antibiotic treatment. Well, in a speaking tour of the United States, as the United States medical service was preparing to enter the Second World War. He stressed a series of pitfalls or as he called them cardinal sins of war surgery. The very first one he said was the unnecessary operations of on through and through bullet wounds of soft parts. The majority of these heel with rest and their early antibiotic heal rapidly with no disability. Operation means loss of time and loss of function. Then goes on to say removal of skin is a cardinal sin. Skin of all structures is the most viable. The most resistant to infection. The most irreplaceable and um circumcision of entry and exit wounds is the hallmark of the novice so fairly strident uh polemic against uh excessive excision of skin. He does say very clearly, it maybe split to give access to deeper structures and we'll talk more about incision later on but never exercised. And that's a key distinction to understand that we'll focus on a bit more detail. 0.3. He makes his third cardinal thin. I would argue is just reiteration of his first cardinal sin. That is how important he regards this wide excision of muscle, especially transverse sections and muscle groups in order to expose a gunshot track, the subsequent disability is shocking and quite unnecessary. He is warning of the possible situation where the surgeon inadvertently does more damage to the patient than the original bullet itself. And that's something we need to tease into. Um we need to drill into this a little more detail. And I particularly immediately when I read something like this and it is a very authoritative author, but completely at odds with our modern thinking. I, I immediately want to go back and look at the experimental evidence. So we've got two very strong opinions on opposing views. And I'm asking myself, what is the experimental evidence on this, on this question? And I could only find to um studies both of which are animal based studies, both of which are performed by authors who were military surgeons. And they did these studies after experience of um serving in um in a conflict environment. So the first one, the first author was Martin Fackler, very famous uh us surgeon and ballistics expert. And he on a study of 20 dogs, he found that through and through soft tissue wounds heal just as well with conservative versus more aggressive radical treatment. The second paper um was um from kind of what's again a a surgeon I believe had experience in the Korean War came back and um the the paper on sheep. And again, he found that aggressive laying open a bullet tracks wasn't necessary in sheep that had been injured with through and through soft tissue limb wounds from high energy type of uh type of weapon systems. So in short, the only animal based by caveat that animal based studies. But the only studies that have been performed on this area do seem to indicate that it is possible to treat these injuries in a more measured way after correctly assessing the type of injury, the amount of energy transfer. But those which are low energy transfer do not require very aggressive treatment. So let's look at the pathophysiology of of what's going on. So in this section, we're going to look at the ballistic factors. We're going to look at the differences in tissues. And we're going to look at this question of wound evolution. So you can break down the nature of the bullet wound into a number of sections. So the first one is the permanent cavity and this is best understood is the wound track. So this is the whole or passage that the bullet makes as a party through tissue. It's approximately the the width of the projectile itself. Um And this is known as uh the permanent cavity, the temporary cavity is the effect you see from cavitation in and this is the bubble or stretch that occurs in the path of the bullet as the bullet passes through. Um And as the tissues are accelerated radially away from the the passage of the perpendicular to the passage of the of the bullet, there is definitely a hydrostatic shockwave that occurs in the tissues. Very controversial, but it is unlikely to contribute significantly to the kind of energies that we would see as surgeons. So it's best just to just to ignore this. But I've included this for completeness. This picture here quite clearly shows the shockwave being formed um ahead of it's a supersonic sound wave. Uh for one of a better description that occurs with a, with a handgun discharge. So let's look at the how those factors relate to tissues because this is where engineering or physics meets biology. And the the key thing to understand here is different body tissues tolerate stretch in different ways. So this cavitation effect, although very impressive on slow motion videos of ballistic gelatin that we've all seen on, on on the internet, it it doesn't necessarily apply or correlate directly to wounding patterns that we see. So let's first of all, look at this image that we've seen before in a bit more detail. You can see that the skin as we know how elastic skin is, it tolerates stretch very well as a couple of small radial tears away from the path. But all in all that skin looks relatively healthy. Look at lung tissue, we know that lung is very, very stretchy tissue, it stretches with chest expansion and contraction all of the time. And therefore, that's tissue that actually tolerates uh tolerates injury, uh moderately, moderately well, skeletal muscle, skeletal muscle, by definition is stretching continuously and again, it's very strong, it's very resistant and this will tolerate stretching relatively well, liver with its very regulated structure. In case by a capsule does not stretch and gunshot wound to the liver with cavitation will produce a devastating uh injury, bone tissue. As we can see here, obviously, has very limited elasticity and rapidly fragments, producing a very complicated severe wound with loss of the function of that bone very rapidly. As you can see here, this radiograph that we've seen previously. So what are some of the aggravating factors that can exacerbate the complexity of uh of wounds? So the first one, the obvious one is instability. So if around or projectile or bullet is unstable when it strikes tissue, it's going to produce um uh it's going to be able to transfer that kinetic energy very rapidly into, into the tissues. If it's not traveling in the stable flight with a, a pointed end of the bullet entering the tissue first, it's like to be slowed down very rapidly by the body tissues as there's a significant amount of drag. And you'll therefore get a lot more tissue stretch and damage similar or the effects that we can see that causes the instability would be ricochet tumbling or if it's been um already passed through clothing or equipment and that can uh lead to unstable, around striking the tissues. And these can be quite complicated entries. It's worth understanding that the energy that we see in these energy ballistic energy transfer wounds are typically much greater than we see in conventional injuries. And it's worth looking at the, the way the tissue response to that. And that again, we can divide under three main groups. So the primary injury is the tissue that's destroyed um within seconds or minutes. Um As the tissue is shared crushed and lacerated by the passage of the, of the bullet. And that's um that's almost immediately crisis. There's been a secondary effect where damaged tissue um that has been stretched and traumatized. Um That's been damaged by the extracellular leakage of intracellular components from the chronic tissue undergoes a more planned apoptosis over the next 24 48 hours. Um And then finally, there's the tertiary injury which is the predominantly seen in incomplete or untreated gunshot wounds where you get swelling and increased pressure, local and regional compartment syndromes, you get infection and then you get quite potentially very significant further tissue damage. Um and that typically occurs between 24 72 hours. And of course, that damage can be so severe, particularly infection that you can rapidly progress towards sepsis and fatality. And that's why untreated relatively simple extremity wounds from gunshots can cause fatalities from from 24 hours. On words, if they are under treated, the key thing to understand is that when you're assessing a gunshot wound, you're assessing at a point of time and it might continue to evolve for 72 hours or so after after initial injury. So let's look at treatment now. Um So I'd like to divide this into uh incision, excision and stabilization. Uh But first of all, we've got to do decision. So that's the assessment of the amount of energy that's transferred into the wound. And we've talked about that in detail. So, incision is the the the opening of the skin and fascia to allow you to fully assess the wound internally, allows you to decompress muscle compartments and allowed you to explore excision is the removal of nonviable tissue and contamination. And I prefer to use the terms incision and excision separately to describe the stages of uh of the surgery rather than the capsule term out debridement, which means different things to different people and also offending are French colleagues with my pronunciation. Stabilization is key. I'm not going to go into a lot of detail about the different stabilisation techniques from plaster cast to external fixation. But this is all about preventing inflammatory response, allowing a patient to be nursed and transferred humanely, which is very important with battlefield surgery where patient may well be evacuated, to say for more rearward medical treatment facilities and also prevents ongoing local tissue damage. In an unstable skeletal environment. We do know from animal work that unstable fractures are more prone to infection. So let's look at incision. So, incision allows the wound to be explored and decompressed. It allows the extra date from necrotic and a pop ptotic tissue to drain stops, build up and reduces the risk of pressure areas and this is all about preventing tertiary injury. Excision is removal of necrotic material from the primary injury, removing the tissue that you think is so badly traumatized is unlikely to undergo apoptosis. So, if you think a tissue area is clearly very damaged and it was dubious viability, you may well consider excising that because the next time the patient is operated on the second look. Well, the take back that might be in 48 hours. And if that area of dubious looking tissue dies six hours after your surgery, you'll be sitting in the wound for 36 hours. The removing of frankly necrotic material will prevent the development of infection. Of course, one of the main drivers of tertiary injury and tissue destruction, instability, the systemic and local effects to this. So instability can cause systemic effects by making the patient in mobile, stopping the patient from being able to sit up and and ventilate properly. It movement of uh mobile long bone fractures will directly drive an inflammatory response by uh interleukins two and six and critically. Uh This is awesome ongoing pain and distress for the patient locally. As we discussed, that is ongoing tissue damage when fracture ends haven't been stabilized. So that constant movement, particularly the patient has to be transferred will be creating or driving further local tissue damage as well. And the net result of this is a greater risk of local infection. So thinking about some tricks and tips here. So the first one is when we're doing the assessment, think about the, think about the wound, look at the wound and the patient in front of you and not worrying about the nature of the weapon system. Um We've all heard handovers where people talk about someone having been shot with a high energy or even more irritatingly to me, a high velocity rifle or weapon system and it's irrelevant. It's all about the nature of the energy transfer and the type of wound that you're seeing in the, in the, in the patient with low energy limb wounds. These can be a low priority, especially if you have multiple casualties. So these can be splinted, treated with the antibiotics and they surgery could be performed on them at a later time. If you only have one patient, obviously that that is your priority. But in multiple casualties, you can assign these a lower priority for surgery if you aren't going to be able to monitor a patient continuously. So if the patient isn't staying in your care, if a patient is going to be transferred for long distances, but either by air by road, by rail without access to a surgical team that can take them back to an operating theater within hours. If they become concerned, then you should be more radical and more aggressive with your excision. It is a much safer approach for the patient that you, that you aren't gonna be able to look after yourself. Another another time to be more radical is if a wound is presenting later, the patient will more likely be moving along that tertiary injury pathway. And so you are going to have to be more aggressive with your with your assessment. The next point I make is to definitively fix these um injuries very robustly. Um So this is example of a low energy weapon system producing a high energy transfer. You've got a essentially this was from a handgun, it was a nine millimeter handgun wound, producing a high energy transfer and high energy transfer wound. So you've got fragmentation of the bullet fragmentation of a proximal femur in a in a relatively young man. So very strong bone that's been uh fractured in multiple pieces. So a very high energy wound, we know that bone is deeply traumatized by impact at high energies. If you think about the ability of bone tissue to transfer um or transmit this strain wave. Um two areas more distant from the immediate point of impact, you're going to get a lot of damage to bone tissue that may well be perfused. This in turn makes the bone recovery quite slow or the potential for a very slow recovery and slow progression to union. And therefore, you've got to provide a very robust fix. So this isn't one of my patient's and there's a number of comments that we can make about this X ray, but the point on using this image to illustrate is the fact that if this fracture doesn't heal up in the next few months, the metal construct that they've chosen here is likely going to fail. So it's common and normal to see a very slow rate of union of ballistic fractures. And therefore, you've got to recognize that with the type of bony fixation constructs you use. So uh you can see my Twitter handle there. If there are any questions, please feel free to get in touch with me through social media and I'll happily debate um any of the elements we brought up and I wish anyone watching this the best of luck in treating these very complicated injury patterns. Thank you.