Popliteal Artery Entrapment Syndrome (PAES)

Overview

Popliteal artery entrapment syndrome (PAES) is a rare condition that occurs when the popliteal artery, the main artery running from the thigh to the calf, is compressed by an enlarged or improperly positioned calf muscle behind the knee. The gastrocnemius muscle, which attaches to the thigh bone, can cause this compression when it contracts during foot plantar flexion, making it difficult for blood to flow to the lower leg and foot.

Repetitive compression during exercise can cause spasms in your arteries, which can reduce blood flow. As a result, lactic acid and carbon dioxide can build up in your muscles and nerves, leading to sensations of fatigue, achiness, heaviness, and, in some cases, numbness in your calf and foot.

After stopping the exercise, the symptoms usually show improvement within three to five minutes. However, if left untreated, the spasm tends to happen more quickly and persist for a longer duration over time. The symptoms also tend to occur after covering a shorter distance, and the recovery time increases.

Symptoms

PAES typically presents with discomfort or cramping in the posterior lower leg (calf) that arises during physical activity and subsides after a period of rest. Additional warning signs and symptoms could be:

• The calf has numbness
• The feet feels cold after exercise
• Paresthesia, characterized by a tingling or burning sensation in the calf muscle

In case the calf muscle entraps the popliteal vein nearby, the symptoms you may experience include:

• The leg feels heavy
• Cramps of the lower legs in the evening
• Swollen or discolored calf
• The lower leg has clots of blood, also called Deep Vein Thrombosis (DVT)

Leg pain symptoms generally tend to impact individuals who are under the age of 40 and in good health. It is advisable to seek medical attention from your doctor if you experience any type of leg pain, particularly if you experience cramping in your calf or foot during physical activity that subsides after rest.

Causes

Popliteal artery entrapment syndrome (PAES) is a medical condition that occurs when the calf muscle, particularly the gastrocnemius muscle, abnormally presses on the main artery located at the back of the knee known as the popliteal artery. This pressure reduces blood flow to the lower leg, resulting in pain and cramping in the back of the lower leg during times of physical activity. The condition may either be present at birth (congenital) or develop later in life. In congenital PAES, the calf muscle or adjacent artery is positioned abnormally during fetal development. Meanwhile, acquired PAES is characterized by an enlarged calf muscle that can press on the popliteal artery.

Risk factors

Popliteal artery entrapment syndrome (PAES) is a relatively rare medical condition. However, certain factors may increase your likelihood of developing it, including:

• Age. PAES is commonly seen in individuals in their late teens or 20s and is rarely diagnosed in those over the age of 40.
• Gender. Although PAES can happen to anyone, and is more prevalent in young men.
• Sports activity. People who engage in activities such as running, cycling, and weight training routines that require the use of the lower extremities and muscles are at a higher risk of developing PAES.