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Popliteal artery aneurysm: why it is dangerous and when treatment is needed
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A popliteal artery aneurysm is a widening of the artery behind the knee to more than 1.5 cm (its normal diameter is 5–9 mm). It is the most common aneurysm of the limb arteries and usually occurs in men over 60. Its danger is not rupture but a thrombus (blood clot) that can block the arteries of the lower leg and foot and put the leg at risk. That is why such an aneurysm is treated before any symptoms appear once it has reached a certain size.
Why it is dangerous: clotting and blockage, not rupture
Blood flows more slowly in the widened artery, and clots form. Small fragments of these clots can break off unnoticed and block the arteries of the lower leg and foot; over time the aneurysm itself may become blocked. Blood supply to the leg then worsens sharply, and the lower-leg arteries that were blocked earlier make it harder to restore. Rupture of a popliteal artery aneurysm is rare.
Symptoms: pulsation behind the knee, calf pain, dark spots on the toes
- Often there are no symptoms: the aneurysm is found by chance on ultrasound or as a pulsating lump behind the knee
- Calf pain when walking that goes away after stopping
- Painful blue or dark spots on the toes — a sign of small clots
- Swelling of the lower leg due to compression of a vein (rare)
When it is urgent
Sudden pain, coldness, pallor or numbness in a leg: call an ambulance (103 in Ukraine). If these signs appear or sharply worsen over minutes or hours, especially with weakness of the foot or inability to move the toes, this may be acute limb ischemia — a sudden occlusion (blockage) of an artery. Irreversible tissue damage can develop within hours (roughly six), so do not wait until morning, do not warm the leg with a heating pad or hot water, and do not rub it.
Sudden severe pain and a tense, rapidly growing swelling behind the knee: call an ambulance (103 in Ukraine). This may be a sign of aneurysm rupture.
Painful blue or dark spots on the toes in a person with a popliteal artery aneurysm need assessment by a vascular surgeon within days.
Tests: ultrasound, CT angiography, the other leg and the abdominal aorta
The aneurysm is reliably detected by duplex ultrasound of the leg arteries, which also shows its diameter, whether it contains a clot and whether the lower-leg arteries are open (patent). CT or MR angiography is done to plan treatment.
Almost half of patients have an aneurysm behind both knees, and about a third also have an abdominal aortic aneurysm. That is why every patient with a popliteal artery aneurysm has the other leg and the abdominal aorta checked.
At what size treatment is needed, and when monitoring is enough
Treatment is recommended for an aneurysm 2 cm or more in diameter, even if it causes no symptoms. In patients at high risk from surgery, especially when there is no clot in the aneurysm, treatment can be deferred until the diameter reaches 3 cm, with regular monitoring. A smaller aneurysm may also be treated if it contains a clot and there are signs of fragments breaking off, or if the lower-leg arteries are already partly blocked. An aneurysm that has caused symptoms is treated regardless of size.
A small aneurysm without a clot is monitored, usually with an ultrasound once a year. Medicines do not shrink an aneurysm, but preventing atherosclerosis, stopping smoking and controlling blood pressure remain important.
How it is treated: bypass with your own vein
The main treatment is open surgery: a bypass around the aneurysm using the patient's own vein, with the aneurysm excluded from the circulation. Such a bypass gives a long-lasting result. Open arterial surgery at the Center is performed by the vascular surgery department; the method and timing of treatment are chosen individually.
After treatment: follow-up ultrasound and monitoring
After surgery, follow-up visits with ultrasound are needed on a schedule set by the doctor. The other leg and the abdominal aorta are also monitored for life, because new aneurysms can develop over time in these patients.
Frequently asked questions
My popliteal artery aneurysm is 15–18 mm. Do I need surgery?
Usually not: such an aneurysm is monitored with an ultrasound once a year. Treatment is offered earlier if the aneurysm is already causing symptoms, if it contains a clot and there are signs of fragments breaking off, or if the lower-leg arteries are already partly blocked.
Can a popliteal artery aneurysm rupture?
It can, but rarely. The main danger is different: a clot in the aneurysm that can block the arteries of the lower leg and foot, or the aneurysm itself. With sudden severe pain in the leg or behind the knee, or a cold, pale or numb foot, call an ambulance (103 in Ukraine).
Why check the other leg and the abdominal aorta if the aneurysm is behind one knee?
Almost half of patients have an aneurysm on both sides, and about a third also have an abdominal aortic aneurysm. These are detected with ultrasound.
Can a popliteal artery aneurysm be cured with pills?
No. Medicines have not been shown to shrink the aneurysm or prevent it from becoming blocked. They are prescribed to prevent atherosclerosis, while the aneurysm itself, when indicated, is treated with surgery.
I can feel a pulse behind my knee. Is it an aneurysm?
Not necessarily: the pulse of the popliteal artery can be felt in healthy people too. If a pulsating lump can be felt behind the knee, especially in an older man, an ultrasound of the leg arteries is worthwhile.
Book a consultation
Vascular surgeon consultation at the Shalimov Center, 30 Akademika Shalimova St, Kyiv. Booking and questions go through the contact doctor, Yurii Vahis. Patients from other cities and abroad can arrange an online consultation.