Anatomy of the Popliteal Artery
The popliteal artery 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 lower leg and foot.
The popliteal artery extends from the femoral artery of the upper leg. The femoral artery comes into contact with the femur bone about a hands length about the knee and then curves to the back of the knee deep into the popliteal fossa. Here the popliteal artery is covered by a thick fascia which 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
PAA causes symptoms in two-thirds of patients, which includes pain, numbness, tingling sensations, 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).
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 clots which breaks away from the artery and may flow to the heart, brain or lungs causing serious disease injury or death
Causes and Occurrence
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 popliteal artery aneurisms 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.
Diagnosis and Treatment
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. It is important to treat any symptoms as early as possible to avoid complications.
Clark, Micheal: Clinical Medicine Fourth Edition. Saunders, London, UK. 2000