- Fractures account for approximately 75 percent of cases of ACS
- ACS is seen more often in patients under 35 years of age
- Symptoms of ACS can include the following:
- Pain out of proportion to apparent injury (early and common finding)
- Persistent deep ache or burning pain
- Paresthesias (onset within approximately 30 minutes to two hours of ACS; suggests ischemic nerve dysfunction)
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The human body has a number of closed spaces called compartments. Several of these compartments, as shown in the illustrations located below, are found in the arms and legs. As seen in the cross-section images of these illustrations, each of these compartments contain muscles, tendons, and nerves, which are encased within dense connective tissue called fascia.
Although compartments are located in other parts of the body, such as the abdomen and buttocks, Compartment Syndrome most often occurs in the arms and legs.
Compartment Syndrome can either be acute or chronic. Acute Compartment Syndrome typically occurs after an injury to the arm or leg. It develops quickly and is likely due to fluid buildup within the compartment from swelling and/or blood. The most common cause of Acute Compartment Syndrome is a fracture of one of the bones in the arm or leg. Although not overly common, Acute Compartment Syndrome has been reported to develop in 1 to 10 percent of tibia bone fractures. The other recognized causes of Acute Compartment Syndrome are burns, crush injuries and casts which are applied too tightly.
Conversely, Chronic Compartment Syndrome occurs with repetitive stress. As a result, marathon runners and competitive bicyclists are at increased risk for the development of Compartment Syndrome. In addition to repetitive stress injuries, the use of anabolic steroids has been associated with Chronic Compartment Syndrome. Unlike Acute Compartment Syndrome, which only affects one arm or leg, Chronic Compartment Syndrome usually is bilateral and affects both arms and legs.
MECHANISM OF INJURY
Compartment Syndrome is caused by the buildup of pressure within one of the compartments. Following an injury, blood or fluid caused by swelling can accumulate within the compartment. Because the walls of the compartment are formed fascia, which is dense and inelastic, blood or fluid that accumulates within the compartment cause pressure inside the compartment to rise.
The pressure inside a compartment can be measured by a hand-held device called a manometer which works by injecting a small amount of liquid solution into the compartment and then measuring the tissue pressure resistance. If Compartment Syndrome is suspected, these devices are essential to making an accurate diagnosis. Normal compartment pressure measurements are between 0 and 8mmHg. If the pressure inside a compartment reaches 20mmHg, patients often experience pain.
If the pressure continues to rise above 20mmHg, it can significantly limit or prevent blood flow to inside of the compartment, in its entirety. If this occurs, the impacted arm or leg becomes at significant risk for massive tissue damage. This is because when blood flow into the compartment is compromised, the tissue within the compartment no longer receives sufficient quantities of the oxygen-rich blood it requires to remain viable. When Compartment Syndrome occurs over a prolonged period of time, toxins are released into the body from decaying and dying muscle tissue that can accumulate in the kidneys and cause kidney failure.
Following an injury, Compartment Syndrome can take several hours to develop. The following 5 signs and symptoms, commonly referred to as the 5 “P’s” should represent red flags to a physician or other health care professional as to an evolving Compartment Syndrome:
- PAIN OUT OF PROPORTION
- Although pain is always present with a fracture, pain that exists after pain medication has been administered or which increases rather than decreases over time and is “out of proportion” to the injury itself, should raise a suspicion as to Compartment Syndrome.
- This is a “pins and needles” sensation or numbness that develops in the injured extremity and is suggestive of nerve damage from rising pressure inside the compartment.
- When blood flow inside the compartment becomes compromised, the skin becomes pale and cool to the touch.
- When muscle and nerve damage occur from increasing compartment pressure, a corresponding inability to move the affected arm or leg will occur.
- The absence of a pulse can be caused by reduced blood flow from increasing pressure inside the compartment.
Compartment Syndrome must be treated immediately as the condition will progress without treatment. The only effective treatment for Compartment Syndrome is the performance of an emergent fasciotomy. As shown below, a fasciotomy involves the creation of surgical incisions to relieve pressure that has developed inside the compartment. Time is of the essence as fasciotomies performed within 24 hours of the onset of Compartment Syndrome have a better prognosis. Failure to perform a fasciotomy can lead to the complete loss of function and in some cases, amputation.