A popliteal artery aneurysm is a localized dilation of the popliteal artery, which runs behind the knee and supplies blood to the lower leg. It is the most common type of peripheral artery aneurysm and is often associated with aneurysms in other parts of the body, especially the abdominal aorta.

Many popliteal artery aneurysms do not cause symptoms initially and may be found during imaging for other conditions. When symptoms do occur, they can include a pulsatile mass behind the knee, leg pain, swelling, numbness, or coldness in the foot. The most serious complications are thrombosis (clot formation), embolization (clots traveling to the lower leg), or limb-threatening ischemia, rather than rupture, which is rare in this location.

Risk factors include atherosclerosis, smoking, high blood pressure, and a family history of aneurysms. Diagnosis is made with duplex ultrasound, CT angiography, or MR angiography.

Management depends on the size, presence of symptoms, and risk of complications. Treatment options include endovascular repair with a stent graft or open surgical repair. Timely diagnosis and treatment are important to prevent limb loss due to impaired blood flow.