Anterior Compartment Syndrome
Painful And Dangerous

Anterior Compartment Syndrome is a painful and potentially dangerous condition brought about by severe shin splints and/or a sudden, hard impact to the shins.

We've all had aches and bruises. But they heal and go away, for the most part.

But imagine getting kicked in the shins by your kids, or during a soccer game, and the front of your shins get swollen, tight, painful, discolored, and it either stays like that for a LONG time, or it continues to get worse, worse, and suddenly you get a huge fissure in your muscle and skin as the pressure basically pops your leg.


Anterior Compartment Syndrome of the lower leg is no fun.

What Is Anterior Compartment Syndrome?

The Tibials Anterior muscle is the main muscle there at the front of you shin. It tilts your ankle up.

That entire muscle is wrapped in connective tissue, which connects by connetive tissue to surrounding muscles and skin.

A encompassing sheet of connective called The Anterior Compartment then wraps the group of muscles called the Dorsiflexors.

The Dorsiflexors consist of the tibialis anterior, extensor hallucis longus, extensor digitorum longus, fibularis tertius.

The sheath of connective tissue is basically a balloon around all those structures.

Now imagine that for some reason, fluid starts to fill that balloon. More is coming in that leaves.

What happens to ballons when they get filled up? They expand.

What happens when the fill up too much? They explode because they can no longer contain all that pressure.

Most people suffering from Anterior Compartment Syndrome are just dealing with pain from pressure buid up. Most of the time, it is painful, there is pressure, but they stay off it and sooner or later it starts to fade away.

Some people end up in the emergency room either before or after their balloon splits.

(The balloon analagy is a nice, clean analogy. Imagine your shin splitting open like a watermelon....)

Let's avoid that, shall we?

How Do You Get Anterior Compartment Syndrome In The Lower Limb(s)?

here are two primary ways to get compartment syndrome of the lower leg.

Really bad, progressive Shin Splints Tendonitis, and a sudden, deeply bruising blow to the shin muscles.

Shin Splint Tendonitis --> ACS

To save myself some typing, I'm going to point you to the Tendonitis and Process of Inflammation pages. Make sure that you understand how they work.

Ok, so you know that Tendonitis and Inflammation work together to create a progressive dynamic of increasing tightness and pain.

In a Shin Splints situation, the dense, close-to-the-bone muscles, primarily the Tibialis Anterior, get tight, constricted by tightening connective tissue, and pull on their connections too hard everytime you use them.

Inflammation traps fluid in the area and makes you hurt more, which makes your body create more inflammation that traps more fluid and release more pain enhancing chemicals.

If this Tendonitis dynamic is really bad, and then you irritate it by going for a run or otherwise working it too hard, the body can go into overdrive and pump a lot of extra fluid in the area.

This swelling is usually not much of a problem.

But if the return system and structure are already overwhelmed with swelling, and then there's a new rush of inflammation's extra fluid, something bad happens.

At a certain point of getting overwhelmed, the lymph system, the return system, will essentially shut off. Meaning, VERY LITTLE fluid can get out.

But new fluid is still coming in. The balloon starts to fill and stretch.

Obviously, your shin structure can't expand too much. And it's not really a balloon, it's more like thousands of balloons with fluid in between and more and more compression from the all directions.

This is a problem but not -horrible- if the growing pressure slows or evens out. But if it's in overdrive, get yourself to the hospital.

And you'll -know- you need to go!

Kicked In The Shin --> ACS

I was reminded that I needed to create this page because a young female soccer player wrote to me and described her symptoms.

That conversation is here: Kicked in the Shins

So imagine that you're playing soccer, or you walk into something, or you get in a car accident, or somehow or other you take a heavy blow to the muscles of the shin.

You bruise. You swell.

Normally, this is not a problem. But again, what if that swelling gets trapped in the Anterior Compartment?

Swelling is bad enough, but what if it gets locked in place for weeks or months.

What if two months later, you're still hurting from interior pressure, still bruised and discolored, and you take another blow? Or your system just decides it's overwhelmed and tries to protect you with even more inflammation....

More Swelling! More Pain!

And possibly a trip to the ER!


The Dangers Of Anterior Compartment Syndrome

Kids Kicked Her In The Legs is another conversation from Ask The Tendonitis Expert collection of Q&A that illustrates one danger of Anterior Compartment Syndrome...and that is DVT.

DVT stands for Deep Vein Thrombosis, which is a blood clot. If you get deep bruising or hematoma, you can get a blood clot.

Shin Splints of any degree won't give you DVT, but if it turns into Anterior Compartment Syndrome, that can change things.

A sudden blow causing a hematoma is more concerning for DVT.

Myositis Ossificans is an unlikely danger, but depending on -why- you have ACS, it's something to watch out for and to avoid.

Myositis Ossificans, or calcified hematoma, or calcified bruising, depending on what you want to call it, means that there is bleeding and swelling in the muscle (hematoma) that calcifies into bone.

Imagine haveing a growth of bone in the middle of your muscle structure. Not necessarily dangerous, but imagine getting kicked there again....

See more about Myositis Ossificans.

Cell Death from all the trapped fluid, as well as the ripping component of all the overpressure, is a danger of Anterior Compartment Syndrome.

Normally with swelling, nutrition has a hard time getting to it's target cells through all the extra fluid.

With ACS, not only does it have extra fluid to deal with, but it has a tightly compressed quagmire of almost no circulation/movement.

If your cells start dying, that causes it's own problems.

Too Much Pressure can cause your structure to crack open like a watermelon.

Literally. I won't describe it more than that.

Anterior Compartment Syndrome is not joke. Unless it's severe and acute, most people think it's just a bruise, just swelling. But if you press on your shin and it's tight like a basketball, it's time to start paying real attention and start turning it around.

P.S. If anybody has a picture of their scar from their Anterior Compartment Syndrome surgery I'd love to put it on this page.

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