Aneurysms are swellings and dilated areas in blood vessels which cause their walls to be weakened and even become burst or nicked, causing internal bleeding. Blood clots may also occur. A popliteal artery aneurysm or PAA is a dilation of the artery that runs behind the knee. This artery supplies the lower leg and foot with blood and treatment is critical to prevent any blockages.
Where is the Popliteal Artery?
The popliteal artery is a branched artery that directly supplies blood to the knee joint and surrounding muscles as well as to the calf and lower thigh muscles. It runs parallel to the popliteal vein and its branches supply blood to the feet.
The popliteal artery extends from the femoral artery of the upper leg. It begins where the femoral artery comes into contact with the femur bone about a hands length above the knee. The artery curves to the back of the knee deep in the popliteal fossa where it is covered by a thick fascia. This thick covering makes it difficult to palpate the artery and detect a pulse at the back of the knee. The popliteal artery continues down the lower leg and divides into the anterior and posterior tibial arteries about a hands length below the knee.
Symptoms and Risks of an Aneurysm Include Emboli, Gangrene
PAA causes symptoms in two-thirds of patients, which includes pain, numbness, ischemia (poor circulation) in the legs and feet, compression of nerves and veins in the legs, edema (swelling) and deep vein thrombosis (clots in the veins). Individuals with varicose veins may be more susceptible to popliteal aneurysms.
If left untreated, PAAs may lead to severe complications, including leg gangrene (tissue death) which may require amputation. If a thrombus (blood clot) is present in the artery, blood flow is stemmed or cut off to the lower leg and foot leading to ischemia. Thrombosis is present in 55% of PAA and embolisms are seen in up to 25% of patients. An embolus is a clot which breaks away from the artery and may flow to the heart, brain or lungs causing serious disease injury or death.
What Causes an Aneurysm?
Popliteal artery aneurysms are the most common artery aneurysms in the peripheral body (the head and limbs), making up almost 85% of all peripheral aneurysms. The average age of individuals suffering from this type of aneurysm is 65 years and over 95% are males. Up to 40% of patients with PAAs also have abdominal artery aneurysms and 50% of cases are bilateral (affecting both legs).
The leading cause of a popliteal artery aneurysm is atherosclerosis (hardening of the walls of the artery); hence patients with diabetes, high cholesterol, obesity and other high risk factors are more likely to suffer from a PAA. Other causes may include genetic defects, inflammation and injury.
Test and Treatments for Aneurysms, Blood Clots
A physical examination and an ultrasound is required to diagnose a PAA. Treatment depends on the size of the aneurysm and whether a clot is present. Patients may require surgery, in which the aneurysm is removed and the artery is reconnected. In less severe cases, blood thinning medications may help to prevent symptoms. Physiotherapy, exercise, weight management, changes in nutrition and wearing compression hosiery or stockings may also help to improve blood circulation.
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Reference:
Clark, Micheal: Clinical Medicine Fourth Edition. Saunders, London, UK. 2000
Noreen Kassem - Noreen Kassem is a hospital doctor based in London, UK. She has extensive experience in clinical research and an undergraduate honors ...
