Popliteal artery aneurysm

Last revised by Angela Liao on 20 May 2023

Popliteal artery aneurysms are the most common peripheral arterial aneurysm and the second most common aneurysm after abdominal aortic aneurysms.

Overall, popliteal artery aneurysms are uncommon. They occur almost exclusively in males (up to 97%) for unknown reasons 8-9. There is an increased incidence with age.

  • strong association with abdominal aortic aneurysms (AAA); ~ 40% of patients with a popliteal artery aneurysm have a AAA, though only 10-15% of patients with AAA have popliteal artery aneurysms

  • although rare, connective tissue diseases (e.g. Ehlers-Danlos) are associated with multiple arterial aneurysms at an early age 11

  • asymptomatic incidental finding

  • pulsatile mass

  • may present with complications (see below)

Popliteal artery aneurysms are bilateral in 50 to 70% of cases. Their location at the knee point, an area of repeated flexion, may be contributory 10. They can either be true or false aneurysms:

  • often the initial imaging modality of choice 4

  • CT angiography (CTA) is useful for the assessment of vessels distal to the aneurysm

  • MR angiography has poorer spatial resolution than CTA and DSA although newer techniques (e.g. contrast-enhanced equilibrium phase imaging) are showing promise 6

Angiography can directly show mural calcification and aneurysmal dilatation. Although angiography remains the "gold standard" according to vascular surgery literature, aneurysmal dilatation may be masked by thrombus formation within the aneurysmal sac in ~25% of cases 7. Instead, it appears as an acute bend in the course of the popliteal artery at the level of the knee joint - this secondary sign is called the "dog leg" sign 5,7.

Symptomatic aneurysms are treated. Asymptomatic aneurysms >2 cm in diameter are also considered for elective treatment:

  • endovascular insertion of covered stent: flexible soft device (such as ViabahnTM stent graft) has better outcome due to movement at the knee crease; 5 year patency rate for ViabahnTM stent graft is 70%; disadvantages include kinking or fracture of the stent due to excessive movement

  • open surgical repair (usually aneurysmorrhaphy and bypass surgery): vein graft typically used; 5 year patency rate of vein graft is also 70%

  • distal thromboembolism (commonest: occurs in 18-31% of untreated cases)

  • rupture (rare)

  • pressure effects if large enough

Differential diagnoses (mainly clinical due to transmitted pulsations of the popliteal artery) include:

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Cases and figures

  • Case 1: bilateral
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  • Case 2
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  • Case 2
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  • Case 3: giant aneurysm on MRI
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  • Case 4
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  • Case 5
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  • Case 6
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  • Case 7: bilateral
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  • Case 8: thrombosed aneurysm
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  • Case 9: popliteal artery pseudoaneurysm
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  • Case 10: Popliteal artery aneurysms
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