Popliteal Artery Entrapment Syndrome (PAES)

What is popliteal artery entrapment syndrome (PAES)?

Popliteal artery entrapment syndrome (PAES) is a rare vascular disease that affects the legs of some young athletes. When you have this syndrome, the muscle behind your knee compresses your popliteal artery — the main artery that runs from your thigh to your calf.

The attachment of your gastrocnemius muscle to your thigh bone causes compression. When your gastrocnemius muscle contracts during foot plantar flexion (pushing down), your muscle compresses your artery.

During exercise, repetitive compression leads to spasms of your artery. This reduces blood flow. The reduced blood flow leads to a buildup of lactic acid and carbon dioxide in your muscles and nerves, which produces heaviness, achiness, tiredness and sometimes numbness in your calf and foot.

Symptoms typically improve three to five minutes after stopping the exercise. Without treatment, over time, the spasm tends to occur quicker and last longer. Symptoms occur after a shorter distance and it takes longer to recover.

Who does popliteal artery entrapment syndrome affect?

PAES occurs most often in athletes between the ages of 15 and 25 years old, particularly those who take part in activities and sports that involve running. These include:

• Track.
• Cross country.
• Soccer.
• Lacrosse.
• Field hockey.

How common is popliteal artery entrapment syndrome?

According to estimates, less than 1% of people have PAES. It’s difficult to know the true number of people who have this condition.

Are there any other conditions that may mimic popliteal artery entrapment syndrome?

Chronic exertional compartment syndrome (CECS) is a much more common condition that's also an exercise-induced muscle and nerve condition. It causes pain, swelling and sometimes disability in the affected muscles of your legs or arms. Anyone can develop the condition, but it's more common in young adult runners and athletes who participate in activities that involve repetitive impact.

Some people with popliteal artery entrapment syndrome may also have chronic exertional compartment syndrome. About 5% of people who don’t improve after PAES treatment may find they also have CECS. It’s possible to have both of these conditions at the same time.

Popliteal artery entrapment syndrome (PAES) vs. chronic exertional compartment syndrome (CECS)

To check for PAES, your healthcare provider will get resting leg blood pressures and look for a drop with exercise. To check for CECS, they’ll measure the pressure in the four compartments of your leg before and after exercise. An abnormal rise of the pressure in your calf compartments occurs in CECS.

What does PAES feel like?

Popliteal artery entrapment syndrome symptoms in your calf and/or foot during exercise may include:

• Aching pain.
• Tiredness.
• Heaviness.
• Cramping.
• Numbness.
• Burning.

Symptoms typically go away after three to five minutes of rest. Over time (without treatment), the symptoms tend to happen at shorter distances and take longer to go away.

What causes popliteal artery entrapment syndrome?

There are two main types of compression:

• Anatomic compression: This type of compression accounts for about 10% of cases and seems to be more common in people assigned male at birth. It happens in only one leg in about 70% of cases.
• Non-anatomic compression, functional or physiologic compression: This type of compression tends to occur more commonly in people assigned female at birth. It happens in both legs in more than 90% of cases.

Anatomic compression

This happens because a part of your gastrocnemius muscle crosses over or under your artery. A tendinous band of your muscle can damage your artery. This leads to:

• An ulcer or sore in your artery.
• Buildup of a clot.
• Eventual occlusion (closing or blocking) of your artery or downstream arteries.

There are four different variants of the muscle location in relation to your artery.

Non-anatomic compression, functional or physiologic compression

Your muscles are all in the normal location, but typically insert higher up your thigh bone or on the inside notch of your thigh bone at the knee. This pulls your muscle to the inside with plantar flexion compressing the muscle against your artery.

A muscle located underneath your artery (popliteus muscle) acts as another point of compression. Researchers don’t associate physiologic compression with damage to your artery.

How is popliteal artery entrapment syndrome diagnosed?

A vascular specialist is the type of healthcare provider who can best diagnose PAES. They’ll do a physical exam that includes checking the pulse in your foot and your popliteal artery. They also may look at changes in your pulses when pushing your foot up and down against resistance.

If you have popliteal artery entrapment syndrome, your provider:

• May be able to feel your pulses while you’re resting.
• May have a harder time detecting your pulses when you exercise, flex or extend your foot.

How do you test for popliteal artery entrapment syndrome?

Diagnostic tests measure blood flow through your knee, leg and foot. Imaging can show:

• Normal artery.
• An ulcer forming in your artery.
• Blood clots.
• Aneurysm of your artery (dilation of the blood vessel to more than 50% of normal size).
• Muscle compressing your artery.

Tests may include:

• Ankle-brachial index with exercise: This test measures the blood pressures in your arms and legs before and after exercise. Normally, your blood pressure is the same in your arms and legs and both rise with exercise. When running causes a spasm in your arteries, leg blood pressures drop after exercise to less than 90% of the arm pressures.
• Duplex ultrasound of the popliteal artery with plantar flexion: This test uses sound waves to image your artery and measure blood flow. It allows your provider to look at the arteries of your leg with plantar flexion and at rest to see muscle compression.
• Computed tomographic angiography (CTA) with plantar flexion: This is a type of CT scan that uses dye to look at your leg arteries with plantar flexion and at rest to see muscle compression.
• Magnetic resonance angiography (MRA) with plantar flexion: This test uses a magnetic field and pulses of radio wave energy to look at your leg arteries with plantar flexion and at rest to see muscle compression.

How is PAES treated?

Your healthcare provider can do surgery to remove a small portion of your gastrocnemius and popliteus muscle. This eliminates the compression of your artery and allows normal blood flow to your leg.

The popliteal artery entrapment syndrome surgery takes about an hour. You’ll be asleep under general anesthesia during the procedure.

In more advanced cases of anatomic popliteal entrapment when the popliteal artery is damaged and blocked, your surgeon may need to clean out the artery and patch it or perform a bypass around the blocked section of the artery to restore blood flow.

Surgery is the preferred treatment for popliteal artery entrapment syndrome because it gives excellent results for most people. More than 90% of people who have the surgery have great improvement in their symptoms afterward.

The only non-surgical treatment for the functional type of PAES uses injections of Botulinum toxin A. With CT or ultrasound guidance, your provider injects Botox® or Dysport® into the muscle that’s causing the compression. This temporarily paralyzes the muscle that’s causing symptoms in hopes that the muscle shrinks permanently.

However, this effect only lasts for three to six months. If the muscle doesn’t get smaller, the symptoms will happen again. This has been successful in less than 60% of people a year after treatment.

How long does it take to recover from this treatment?

The popliteal artery entrapment syndrome recovery time after surgery is four to six months.

You’ll need to stay in the hospital overnight after your surgery. Then you may do physical therapy (stretching and flexibility exercises) for the first two weeks as an outpatient to help you recover. After two weeks, you’ll do strength and conditioning exercises until you recover completely.

What can I expect if I have popliteal artery entrapment syndrome?

If you have functional popliteal entrapment and your symptoms of leg pain with exercise aren’t bothersome, you can limit your exercise activity. Your healthcare provider can monitor your condition.

However, surgical treatment is successful in more than 90% of people and it’s unlikely that they’ll have symptoms again. Most athletes return to normal activity after surgery.

For anatomic entrapment, providers recommend surgical removal of the abnormal muscle slips to prevent arterial damage that can occur over time. If you don’t get treatment until after anatomic PAES has damaged your popliteal artery, you could be at risk of always having pain in your legs when you walk. It’s possible to need to have a leg removed. However, this is very rare.

When should I see my healthcare provider?

After surgery, you’ll need follow-up appointments with your healthcare provider:

• In one month.
• In six months.
• In 12 months.

Your office appointments will include:

• Ultrasound of your repaired artery.
• Blood pressure checks in your feet.

If your artery has returned to normal, you won’t need any further follow-up visits unless your symptoms return or you needed a bypass of your artery.

What questions should I ask my doctor?

• Is my PAES anatomic or functional?
• Do you recommend surgery for my specific situation?

A note from Cleveland Clinic

If you’re a young person having leg pain, you should see your healthcare provider. Several problems could be causing the pain. The sooner you get an accurate diagnosis, the earlier you can start getting treatment. If you have popliteal artery entrapment syndrome, talk with your provider about whether surgery is right for you. It’s been a successful treatment in many cases.