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What is a popliteal aneurysm?
The popliteal artery is behind the knee joint and carries blood from the upper to lower part of the leg. A popliteal aneurysm is an abnormal bulging of the popliteal artery.
A popliteal artery is usually considered aneurysmal if its diameter exceeds 1cm.
Who gets popliteal aneurysms?
The risk factors are the same as for other arterial aneurysms, namely family history, smoking, blood pressure etc. In particular, if someone has an aneurysm at another site, popliteal aneurysms are also often seen.
What problems do popliteal aneurysms cause?
With most aneurysms, the main risk is of the aneurysms bursting and causing massive bleeding. Popliteal aneurysms are different, in that the main problem is not rupture, but rather blockage of the aneurysms causing severe shortage of blood supply to the lower leg and foot. This results from blood clot which gradually builds up on the inside wall of the aneurysm. This is called mural thrombus which, over time, causes severe damage to the arteries lower in the leg and foot. If left too late the problem may be difficult to salvage and there is a high risk of amputations. For this reason popliteal aneurysms should be treated before getting too large; 2cm is usually considered as the cut off point.
How are popliteal aneurysms treated?
There are two ways to treat popliteal aneurysms. The most commonly used method is surgical bypass from the femoral artery above the knee to the popliteal artery below the aneurysm using vein taken from the same leg. The aneurysm is then tied off above and below. Such surgery for asymptomatic popliteal aneurysms is very successful with 5-year graft patency of around 80% and limb preservation of over 95%. If treatment is delayed until the aneurysm becomes symptomatic, the outcome is poor with nearly 20% of limbs requiring amputation.
The alternative to bypass surgery is endovascular stenting of the popliteal aneurysm with a covered stent. This can be done quickly and easily under local anaesthetic via the femoral artery in the groin. Not all patients are suitable for this technique, and the long term results do not appear to be quite as good as bypass surgery, but it is a very good method for treating some patients with popliteal aneurysms.