Popliteal artery entrapment syndrome

Overview

Popliteal artery entrapment syndrome (PAES) is an uncommon condition that affects the main artery behind the knee. That artery is called the popliteal artery. In this condition, the calf muscle is in the wrong position or it's larger than usual. The muscle presses on the artery. The artery becomes trapped, making it harder for blood to flow to the lower leg and foot.

Popliteal artery entrapment syndrome is most common among athletes.

Symptoms

The main symptom of popliteal artery entrapment syndrome (PAES) is pain or cramping in the back of the lower leg. The back of the lower leg is called the calf. The pain occurs during exercise and goes away with rest. Other symptoms may include:

• Cold feet after exercise.
• Tingling or burning in your calf.
• Numbness in the calf area.

If the nearby vein, called the popliteal vein, also becomes trapped by the calf muscle, you may have:

• A heavy feeling in the leg.
• Lower leg cramping at night.
• Swelling in the calf area.
• Changes in skin color around the calf muscle.
• Blood clot in the lower leg, called deep vein thrombosis.

Symptoms typically affect young, otherwise healthy people under age 40.

When to see a doctor

Make an appointment for a health checkup if you have any type of leg pain. This is especially important if you have calf or foot cramping during activity that gets better with rest.

Causes

Popliteal artery entrapment syndrome (PAES) is caused by an irregular calf muscle, usually the gastrocnemius muscle.

The condition may be seen at birth, or it may occur later in life. When it's present at birth, the baby's calf muscle or nearby artery forms in the wrong place during pregnancy. People who get the condition later in life have a calf muscle that is bigger than usual.

The changes in the calf muscle cause it to press on the main artery behind the knee. This reduces blood flow to the lower leg. The lack of blood flow causes pain and cramping in the back of the lower leg during times of activity.

Risk factors

Popliteal artery entrapment syndrome (PAES) is uncommon. The following things increase the risk of the condition.

• Younger age. The condition is most often seen in people who are in their late teens or 20s. It's rarely diagnosed in those over age 40.
• Being male. PAES can occur in anyone, but it's much more common in young men.
• Strenuous athletic activity. Runners, bicyclists, and athletes who try to build muscle fast with weight training routines or high-intensity circuit training are at the highest risk.

Complications

Long-term pressure on the popliteal artery can cause the artery to narrow. This is called artery stenosis. It can cause pain and cramping with just slight activity, such as walking.

In severe cases or when undiagnosed, the nerves and muscles in the leg can become damaged. Blood clots may occur in the lower leg. Older athletes with symptoms of popliteal artery entrapment syndrome should be checked for a ballooning or bulging of the artery. This is called a popliteal aneurysm. It is common in older men.