Overview

Popliteal artery entrapment syndrome (PAES) is an uncommon condition in which an abnormally positioned or enlarged calf muscle presses on the main artery behind the knee (popliteal 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.

Popliteal artery entrapment syndrome care at Mayo Clinic

Symptoms

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

  • Cold feet after exercise
  • Tingling or burning in your calf (paresthesia)
  • Numbness in the calf area

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

  • Heavy feeling in the leg
  • Lower leg cramping at night
  • Swelling in the calf area
  • Changes in skin color around the calf muscle
  • Blood clots in the lower leg (deep vein thrombosis)

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

When to see a doctor

See your doctor if you have any type of leg pain, especially if you have calf or foot cramping during activity that gets better with rest.

Causes

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

The condition may occur from birth (congenital) or develop later in life (acquired). In the congenital form, the calf muscle or nearby artery is abnormally positioned while the baby grows in the mother's womb. People with the acquired form of PAES have a calf muscle that is bigger than normal (enlarged).

The abnormal calf muscle presses on the main artery behind the knee (popliteal artery), reducing blood flow to the lower leg. The lack of blood flow results in 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 your 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 (stenosis), causing 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 (deep vein thrombosis). Older athletes with signs and symptoms of popliteal artery entrapment syndrome should be checked for popliteal aneurysm, which is common in older men.