This is the second article in the Post-Apocalyptic World (PAW) Medicine series. As with the original article the purpose is to dispel some of the myths that keep us from recognizing the dangers we might face in a world altered by war, wide-spread disease, famine, economic collapse, extraterrestrial invasion, or a landslide win of both chambers and the Presidency by social democrats.

As before, cheating by Hollywood scriptwriters and PAW authors trying to write their way out of a corner by having their hero take a round through an area of the body they have assume will pose no absolute threat to life – nor apparently limb – tends to color our thinking.

The first article in this series addressed the myth of shoulder wounds. Having burst bubbles far and wide with the dispelling of that favorite (sorry about the spoilers, Hollywood) it is time to move on to our next target. Pun intended.

Myth #2: Leg Wounds Are Inconvenient and Painful, But Not Overly Serious

Like the (in) famous shoulder wound, the leg, particularly the upper leg, is a favorite non-fatal wound target for literary action heroes and TV stars. Once more the prevailing thought seems to be that the upper leg is mostly (muscle) tissue and thus not overly affected by a mere piece of metal passing through at high speed. It’s just a small hole, right? Never mind the lower leg which is both smaller in diameter but has more volume by area filled with not one but now two separate bones.

We haven’t even considered the knee yet. There is another bone – the patella – over a joint no less, the destruction by bullet which means not only will you not be walking now but perhaps not for a very long time.

In the Hollywood/PAW our heroes tend to get ‘winged’ in the leg less frequently than they do the shoulder or upper arm. In the real world the opposite is true by an average factor of nearly 2:1.

But no worries, mate. Just tie a bandana around the leg and hobble on. Do try to make it look like it is painful though, shall we? The blokes will be watching. Just don’t overdo the limping part or it’ll ruin the final scene.

The Reality: They Can Be Far More Serious Than A Shoulder Wound

People in general – perhaps in large part due to the influence of Barbara Scriptwriter and Bob Novelist – tend to see leg wounds as not nearly as threatening as say to the trunk of the body. While it is unquestionably true that there are no organs located in the lower extremities the potential for loss of life due to battlefield-type injury remains significant without proper and prompt treatment.

Again, the reality is far different from how the TV script/fiction novel writers depict it. Using real world reports and data gathered by our military as well as civilian ER sources we can paint a more accurate picture and may alter our perceptions accordingly.

Like the shoulder and arm area there are arteries, veins, tendons, ligaments and other assorted anatomical structures within the leg, whether the upper or lower segment or even the in-between. The muscles of the thighs alone are a complicated bunch. Considering what we ask of our thighs you knew there wouldn’t be a simple mechanism at play. Here is a short – 1 minutes 36 seconds – video illustrating the muscles of the thigh itself.

There are also bones, with the femur (thigh bone) being the largest bone in the body. The lower leg of course has two bones, being the tibia (larger) and the fibula (smaller). In between the two areas we also have the patella, or kneecap.

We have already discussed in the previous article the additional trauma caused to other structures such as arteries, veins, nerves, etc. so will not repeat that here save to state for the record that it remains just as true with leg as arm/shoulder wounds. Just remember, the femoral artery is large, an average of 9-10 mm +/- 0.8 mm in adult males age 25 and older. It increases in size as we age in both males and females. Combat tourniquets are not just for use after IEDs. There is a reason even rural EMS squad’s carry them and it is not due to increasing local gangbanging. (1)

Wartime Lessons Learned

WWI saw a drastic change in the way the wounded were treated. Remember the mass assaults against entrenched machine guns backed by dozens of riflemen? How many of the assaulting troops do you suppose sustained wounds to their arms, heads and torsos as opposed to their lower extremities? If you believe it was likely a much lower number you would be correct. Machine guns swept the field from a height at or below hip level. As a result there were a lot of leg wounds. Death usually resulted from lack of initial first aid or later infection rather than immediate destruction of important organs. In other words it took time, but the fallen were still just as dead.

The treatment of such casualties changed drastically just from 1914 to 1915. Recall the femur, the largest bone in the body? We learned a lot about leg wounds in particular and orthopedics in general in that war, and have been building on that knowledge since. One major change was to adopt the use of the traction splint, the original Thomas model, which proved to be effective when the so-called ‘rifle splint’ did not. That alone drove down mortality rates drastically. Prior to the introduction of the Thomas splint mortality from compound fractures of the femur – usually due to direct gunshot wound – approached 80% due to blood loss.  (2)

The classic portrait of the soldier limping off the field of battle supported by a buddy on one side applies mostly to those struck in the lower leg. If struck in the upper leg – the thigh region – they are much more likely relegated to waiting for the stretcher team because they will not be able to hobble, limp or gimp with a fractured femur, and if struck through the fleshy portion only still may not be able to gimp off due to the effect of cavitation-induced injury. I am sure exceptions to this rule do exist but personally I believe you stand a better chance of making a 4-figure win on a lottery ticket than you do of ambulating with even a simple femur fracture, or a temporarily induced gold ball-sized wound channel in the musculature. Remember the heroically applied bandana? That only works for surface grazes an inch deep or less. If the wound is deeper than that please reread this paragraph and reflect on it.

But it’s Just a Flesh Wound

There we are the favorite of those script and novel writers, the (in) famous flesh wound. But what exactly do we mean by the term? Here’s what Merriam-Webster says about it:

: an injury involving penetration of the body musculature without damage to bones or internal organs

Alternatively they also define it as:

a wound that injures the skin and flesh but does not go deep into the body

I think the latter definition is what most of us think of when we hear term ‘flesh wound.’ In other words, a painful but otherwise relatively harmless wound. Or so the thinking goes.

Interestingly enough the term dates from 1665 – the first known use – but does not appear in the Merck Manual. The term is more colloquial than medical in nature.

Another myth in this area is that a through-and-through wound is good. What the concept does not take into account is that the backside of the ‘through’ may be the proverbial manhole-sized blow-out if the round was tumbling at the time. Once more, so much for the pencil hole theory. Through-and-through or in-and-out again does not automatically imply that the entrance and exit wounds were virtually identical in size. Nor does it take into account the internal damage. Remember that bullet tumble thing? Save the bandana for a sweat rag, you are going to need it.

Repeat After Me: It is NOT Just a Hole

As we learned in the previous article in this series a hole is not just a hole when we are talking about living tissue assaulted by a missile versus a mere penetrating object such as a knife blade. Depending on whether the projectile that caused the wound falls under the low-energy or high-energy range the effects on the tissue – skin, muscle, fascia, veins and arteries – can range from the ‘merely’ damaging to drastic and even catastrophic.  There is also the permanent cavitation (‘the hole’) caused by the passage of an energetic missile through tissue. In contrast a knife also creates a permanent cavity but no temporary cavitation. It is an example of a very low energy wounding.

So just what is cavitation? Basically it is the sudden formation and collapse of a ‘bubble’ within the tissue. The ‘bubble’ is caused by the energy imparted by the passage of a projectile of either low-med or high velocity. The size of the bubble is a product of both the energy imparted and the size of the projectile, AND the behavior of said object. Behavior you say? Yes, how the projectile acts upon entering the flesh, i.e. tumbling or not. (3)

Unlike the pointed, solid nosed bullets of the Maxim and the Vickers et al, today’s 5.56 and 7.62 x 39 mm rounds are designed to be inherently unstable when striking an object such as flesh. In other words they cease moving point first and start to rotate – tumble if you will – as they go through, creating a wound channel at least equal at one point to the length rather than the diameter of the round. So we have a wound channel that somewhere along its path reaches a minimum diameter of either 45 mm or 39 mm, either top to bottom or side to side or somewhere in between. It can be better described as spindle shaped – narrow at the beginning, increasing to several times the original diameter as it progresses, and narrowing again farther on. So much for the pencil hole idea. And there lays an idea for a future article by one of our other authors more learned in the subject of bullet construction and wounding effects than I am.

In the interest of illustrating this important point, however, I recommend taking a minute to peruse the figures [(B] and [C] on page 2 of the referenced article linked to below. (4) It uses the common .22LR vs. the familiar M-193 FMJ .223 round to illustrate rather well the difference in imparted energy levels when we are otherwise talking about virtually identical missile diameters.

Shock Waves Can Break Bones

Besides the permanent cavity of the wound channel itself, and the temporary cavity caused by the cavitation effect, there is also the shockwave to consider. Shockwave is caused by the passage of an energetic projectile such as a bullet or piece of shrapnel – as opposed once again to a knife blade with a maximum velocity of no more than a few dozen feet per second – through a liquid medium. It you recall from your high school biology classes the human body is approximately 60% water, give or take. Thus it tends to act as a liquid when subjected to a sudden outside energy delivery. Hollywood et al fail to take into account this effect. In fact, with enough energy imparted by the temporary cavitation or the pressure wave that accompanies it bones can be fractured without ever being touched by an actual projectile or parts thereof.  (5)

As the tissue spreads outward during the cavitation process it also presses on the tissue surrounding that is not directly stretched. It does not, however, remain entirely unaffected. The ‘shock wave’ effect passes through the unstretched tissue is much the same manner that a concussion can be felt through the earth, though the ground itself well away from the original explosion or impact site does not actually move it transmits vibration. Depending on which study you embrace the shockwave is not thought to cause actual damage, though other researchers seem to disagree.  We do know that concussion alone can and does kill without leaving behind any external evidence of injury.

One study revealed that fractures in gunshot wounds to the lower extremity – In particular to the thigh – are far more likely to involve fractures than do wounds to the upper extremity (arm and shoulder). They reported a rate of femur fracture ranging between 22% and 49%. Ouch! That translates to a 1:2 or 1:4 chance of breaking the largest bone in your body just because you were shot in that limb? Hello Hollywood, did you catch that? (6)

Compartment Syndrome

Both Barbara and Bob, our erstwhile writers, never mention this but it is a very legitimate and hardly unknown complication even when neither bone nor artery, etc. are directly involved. I am going to just touch on this in the hope that one of our surgeon readers might pick up on it and expound with greater knowledge than I possess. I have seen such injuries in my career and understand the mechanism behind them and the treatment involved, but must confess I missed the day we were being taught to perform fasciotomy.

Definition: “Compartment syndrome is defined as an increased interstitial pressure within an enclosed osteofascial space (compartment) that reduces capillary blood perfusion below a level necessary for tissue viability.” (4) [page 14]

In layman’s terms it means increased pressure inside the leg to the point that tissue perfusion – blood flow – is greatly reduced or even eliminated. Onset can be as quick as 15 to 45 minutes after the initial injury. (5) Interestingly enough it occurs more often with open (compound) fractures than with closed. It is less common in the absence of fracture but still occurs. Interestingly enough shotgun wounds produce more instances of compartment syndrome by percentage of cases than do rifle or handgun wounds.

Why does compartment syndrome matter? Because it can easily result in the eventual loss of a limb if untreated, and even loss of life. The majority of cases occur with trauma to the tibia (lower leg) in instances of both blunt and penetrating trauma. (6)

The Take Away

Like shoulder/arm wounds gunshot wounds to the leg are not likely something you can just ‘walk off.’ Nor is ‘Ranger Candy’ likely to allow you to finish the mission. Anything more than an actual graze or shallow furrow can and might well take you out of the action insofar as moving on your own.

The mortality rates  from untreated thigh wounds involving actual femur fracture can be extremely high.

Assuming there is no actual direct bone involvement the temporary shock can and too often will traumatize the vascular spaces (veins, arteries), muscles and even the bones themselves to leave you with a mere Hollywood hero wound.

Though it is true that the major arteries (not all) in the thigh are located in the inner aspect, the opposite is true for the lower leg.

Compartment syndrome can and does occur with through-and-through wounds.

Hollywood lies, and PAW writers are not a reliable source of medical information.

 

  • The Diameter of the Common Femoral Artery in Healthy Human: Influence of Sex, Age, and Body Size Journal of Vascular Surgery Volume 29, Issue 3, March 1999, Pages 503-510

Sandgren, MD;  Sonesson, MD; PhD, Ahlgren, MD;  Länne MD, PhD

https://www.sciencedirect.com/science/article/pii/S074152149970279X

 

  • The First World War and its influence on the development of orthopaedic surgery

T Scotland  J R Coll Physicians Edinb 2014; 44:163–9

https://pdfs.semanticscholar.org/67ce/6b94b065c835930641a9754cfbb958e501e7.pdf

 

  • Physical Mechanisms of Soft Tissue Injury from Penetrating Ballistic Impact

Amy Courtney, Ph.D., Michael Courtney, Ph.D.  DFRL U.S. Air Force Academy

https://apps.dtic.mil/dtic/tr/fulltext/u2/a570804.pdf

 

  • Gunshot Wounds: 1. Bullets, Ballistics, and Mechanisms of Injury American Journal of Roentgenology. 1990;155: 685-690. 10.2214/ajr.155.4.2119095

Jeremy J. Hollerman, Martin L. Fackler, Douglas M. CoIdwelI, and Yoram Ben-Menachem  https://www.ajronline.org/doi/abs/10.2214/ajr.155.4.2119095

 

  • Combat Casualty Care S. Army Medical Department Center and School (AMEDDC&S)

John F. Kragh, Jr., MD, Jess M. Kirby, MD, James R. Ficke, MD

https://www.cs.amedd.army.mil/borden/book/ccc/uclachp9.pdf

 

  • Ballistic Injuries in the Emergency Dept. – Management Of Gunshot Wounds To The Extremities (Bruner et al) Emergency Medicine Practice Vol. 13 Number 12 December 2011

https://www.ebmedicine.net/topics.php?paction=showTopicSeg&topic_id=285&seg_id=5349

 

Reasonable Rascal has been plaguing the internet since 1997 and refuses to go away despite years of jeers. He began his medical career using all the skills the Boy Scouts could teach him and eventually found his way into a more formal career as a Paramedic and Registered Nurse. He is one of the authors of Survival and Austere Medicine, 3rd Edition

 

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