Anatomy
The anterior compartment is a section of the lower leg between the knee and ankles. It is bounded by the tibia and fibula bones on either side,, the tough interosseous membrane between these two bones forms the back wall and a tough outer membrane just below the skin forms the front wall. The anterior compartment contains these four muscles:
- Tibialis anterior
- Extensor digitorum longus
- Extensor hallucis longus
- Fibularis tertius
What is Anterior Compartment Syndrome
The bones as well as the tough membranes forming and back and front walls do not stretch easily when there is any type of swelling within the compartment. As a result, any fluid accumulation that results from let’s say, a pulled muscle,, does not result in swelling as easily as it does in other areas of the body. Instead, there is an increase in pressure as fluid increases from the inflammation.
The result of that increased pressure is that the thinner walled veins and lymph vessels that are contained within the compartment tend to gradually collapse as the pressure increases from an inflammation. The thicker walled arteries however, continue to deliver blood. This results in further increase in fluid in the anterior compartment as blood gets in faster than it can get out. This vicious cycle can continue until the pressure is so severe that it can eventually collapse the arteries as well.
At this point, all of the tissues become starved for oxygen and tissue damage spreads to include all of the muscles, nerves and other tissues in the compartment. This tissue damage resulting from oxygen starvation can be quite severe and can progress to the point of a medical emergency.
Identification
At this stage, you have anterior compartment syndrome and there will be no pulses in the region. The collapsed arteries will also cause the region to be pale, quite the opposite from most painful areas which tend to be more red than normal color. Pain will not be influenced as you would normally expect with analgesics due to the degree and type of tissue damage. Parastesias or tingling will begin in the anterior compartment region or possibly into the foot once the nerves become damaged from lack of oxygen. Paralysis will ultimately occur in the muscles within the compartment and further down into the foot as a result of oxygen starved nerve damage and to some degree even muscle cell death.
Causes
While ACS is most directly the result of a greater than normal amount of damage in an area which cannot tolerate extensive swelling, other factors can contribute to its frequency or severity. These include items that fall roughly into the following categories: 1) increased rate of damage; 2) decreased rate of repair; 3) impaired inflammation regulation.
3) Impaired Inflammation Regulation – Inflammation is a normal part of any repair process. In some people however, there is inflammation disproportionate to the amount of damage they receive. This can happen when: they do not produce enough cortisone (adrenal fatigue, low cholesterol, statin drug side effect); they take in too many inflammation producing chemicals (omega 6 fats, air pollution, non-organic foods, drug reaction, etc.); allergy systemic response (food allergies, ‘hay fever’, etc.),
As with so many health conditions, it is frequently not a matter of just one cause. It is important to explore as many possible contributing factors as you can with your healthcare provider to see which ones are involved and to what degree each is involved. It is not unusual to find that 4-8 different factors involved, each contributing to your specific syndrome profile. Some factors contribute just a little to your ACS, while others contribute a lot. That is why the treatments that worked for your friend or neighbor, might have little to no effect for you. The key is to diagnose the causes first, then treat.
Images courtesy of
1, 2, 4 – Microsoft, used with permission
3 – john Wallman
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