Introduction
The popliteal artery is the main artery running behind the knee to supply blood to the calf and foot. A popliteal aneurysm is a dilatation and enlargement of the popliteal artery. They are the 2nd commonest type of peripheral aneurysm after those involving the aorta. There is a strong association between popliteal aneurysms and aortic aneurysms.
Causes
Similar to aortic aneurysm, the precise cause of popliteal artery aneurysms is not well understood. They are associated with:
- Family history / Genetic pre-disposition.
- Smoking.
- Atherosclerosis.
- Connective tissue disorders (Marfan syndrome, Ehlers-Danlos).
Symptoms
Smaller popliteal aneurysms tend to be asymptomatic. As they get larger there is a small risk of rupture. The main concern with popliteal aneurysms is the risk of clot formation inside the aneurysm. Over time this clot (or thrombus) can dislodge and move (embolise) down the leg. This process can occur over time and eventually may cause a complete occlusion (blockage) of the artery with a high risk of limb loss due to a lack of blood flow. Early warning signs of this include painful or dis-coloured toes, loss of pulses or pain with walking. Rarely popliteal aneurysms cause compression of surrounding structures.
Tests
Ultrasound scans are very reliable at detecting and determining the size of popliteal artery aneurysms. They are also useful at assessing how much clot has formed inside the aneurysm. CT scan is generally used to assess larger aneurysms and to plan treatment.
Diagnosis
Generally, CT angiogram is the best test to confirm an aneurysm and to plan treatment. Ultrasound is used for monitoring of smaller aneurysms.
Treatment
The need for treatment of popliteal artery aneurysms depends on the size of the popliteal aneurysm, how much clot is inside the aneurysm and whether it is causing any symptoms.
Popliteal aneurysms over 2 cm in diameter or those causing symptoms require treatment. Smaller aneurysms < 2cm in diameter are monitored on a regular surveillance program.
Treatment options include:
- Surveillance – 6 monthly ultrasound monitoring.
- Anti-coagulation – only patients at high risk for surgery.
- Stenting – use of a covered stent to seal the aneurysm.
- Surgical repair – direct repair with a graft, or exclusion bypass graft.
Which option is utilised depends on the size, location and symptom status of the aneurysm. Surgical repair is the best option for long term durability and generally stents are used if a patient has other medical issues that increase the risk of surgery. Anatomically not all patients are suitable for stent treatment.
Related Information
Femoral Artery Aneurysms
Peripheral Artery Disease
Arterial Bypass Surgery
Peripheral Artery Stenting