Introduction
The popliteal artery is the main blood supply to the lower leg. The artery may get compressed and have reduced blood flow due to an abnormal path of the popliteal artery and the calf muscle group. The immediate result of decreased flow from calf contractions is cramping and calf pain during exercise. Popliteal artery compression reduces blood flow to the lower leg and, over time, can damage the artery.
What Is Popliteal Entrapment Syndrome?
The popliteal artery entrapment syndrome (PAES) is a rare pathology when myofascial structures compress the popliteal artery in the popliteal fossa. As a result, claudication (pain, discomfort, or tiredness in legs during walking) and chronic leg ischemia (reduced blood flow) occur. This condition primarily affects young athletes rather than the elderly. Patients with PAES typically present with intermittent foot and calf pain exacerbated by exercise and relieved by rest. Anderson Stuart first described the popliteal artery entrapment syndrome (PAES) in a 64-year-old male in 1879.
How Common Is Popliteal Entrapment Syndrome?
On average, less than 1% of the population has popliteal artery entrapment syndrome. In the United States (U.S.), PAES affects between 0.17% and 3.5% of the general population. However, due to the rare occurrence, the number of people suffering from this condition is unknown.
What Causes Popliteal Entrapment Syndrome?
Individuals with popliteal artery entrapment syndrome usually present with alterations during the popliteal artery. The primary event that causes PAES is the abnormal movement of the calf muscle around the vascular bundle during fetal development as the limbs develop.
The problem is triggered by the growth of the calf muscles, which is common for PAES to appear later in the teens and 20s when many young people participate in athletic activities and weight resistance training. Additionally, men are more likely to experience the issue than women. This may result from the quick muscle growth that characterizes male puberty.
Popliteal artery compression leading to PAES may occur due to anatomic or non-anatomic causes. Anatomic compression occurs when the gastrocnemius muscle crosses over the artery. This compression accounts for about 10 % of cases and appears more common in males. In roughly 70% of cases, it only affects one leg. Non-anatomic compression, functional or physiologic compression, is more common in women. In more than 90% of cases, it occurs in both legs.
How Is Popliteal Artery Entrapment Syndrome Classified?
Most PAES cases are caused by embryological anomalies, with fewer patients having acquired causes. The PAES are further classified into six types based on the relationship between the medial head of the gastrocnemius muscle and the popliteal artery.
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Type I - The popliteal artery runs more medially around the gastrocnemius muscle's normal medial head.
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Type II - The gastrocnemius muscle's medial head attaches to the femur more laterally. As a result, the popliteal artery runs medially and inferiorly.
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Type III - An abnormal additional gastrocnemius tendon encircles the popliteal artery.
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Type IV - The popliteus muscle or a fibrous band compresses the popliteal artery.
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Type V - Entrapment of the popliteal artery and vein due to any of the causes mentioned earlier.
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Type VI - Gastrocnemius muscle hypertrophy has entrapped the normally placed popliteal artery.
Who Is Affected by Popliteal Artery Entrapment Syndrome?
About 60 % of all popliteal artery entrapment syndrome cases involve young, physically active men under 30. Additionally, 85 % of patients with this condition are men. The male-to-female ratio for this syndrome is 15:1. People who participate in sports like running, soccer, football, basketball, or weightlifting are likelier to develop this syndrome.
What Are the Symptoms of Popliteal Artery Entrapment Syndrome?
Patients with PAES typically have an onset of symptoms related to exercise, which may include:
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Leg cramping.
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Aching pain.
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Swellings in the calf areas.
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Lower leg pain.
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Numbness of the feet.
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Cold feet.
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Skin color changes in the calf muscle area.
How Is Popliteal Artery Syndrome Diagnosed?
Diagnostic tests for popliteal artery entrapment syndrome measure the blood flow in the leg, knee, and foot.
The typically used diagnostic tests are the following:
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Duplex Ultrasound - In this test, sound waves are used to image the popliteal artery and measure the blood flow. It helps visualize the arteries of the leg and check for muscle compression.
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Computed Tomographic Angiography (CTA) - This CT scan uses dye to examine the leg arteries in plantar flexion and at rest to detect muscle compression.
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Magnetic Resonance Angiography (MRA) - In this test, a magnetic field and radio wave energy pulses are used to examine the leg arteries in plantar flexion and at rest to detect muscle compression.
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Ankle-Brachial Index - This test measures blood pressure in the arms and legs before and after exercise. The blood pressure in the arms and legs is the same, and both rise during exercise. However, when running causes a spasm in the arteries, the leg blood pressure drops to less than 90 % of the arm blood pressure.
What Are the Treatment Options for Popliteal Artery Entrapment Syndrome?
PAES is managed differently depending on the presence or absence of symptoms. Leg function is usually unaffected by surgery to release the calf muscle and artery. A full recovery can be expected when the condition is detected and treated early. The symptoms should go away.
Surgery usually restores normal blood flow to the leg if compression is found and the popliteal artery is still in good condition. During this procedure, an incision is made behind the knee to access the popliteal artery, and the muscle, tendon, or band compressing the artery is released.
The compression could block or change the artery permanently in more difficult situations. For these patients, a vein or artificial graft is used during bypass surgery to get around the blocked artery and open a new passageway for blood to travel to the lower leg. The muscle, tendon, or band that caused the compression is also fixed.
What Are the Complications of Untreated Popliteal Artery Entrapment Syndrome?
Positive outcomes are possible with early detection and management of PAES. On the other hand, persistent popliteal artery compression can result in severe arterial damage, chronic claudication, or even limb loss.
These are some potential PAES complications:
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Popliteal artery thrombosis.
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Distal arterial thromoembolism.
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Popliteal artery stenosis.
Conclusion
Popliteal artery entrapment syndrome (PAES) is a rare limb-threatening vascular condition. This embryologically developmental anomaly is caused primarily by a strange relationship of the popliteal artery with the surrounding popliteal myofascial structures. PAES primarily affects active young males.
