Popliteal aneurysms

Popliteal aneurysms are defined as localized dilations involving all arterial layers, with a diameter exceeding >50% of the adjacent segment or reference standards. They are rare (incidence of 0.1 to 2.8% of cases) but represent approximately 70% of peripheral aneurysms. They are bilateral in ~50% of cases and predominantly affect men (>90% of patients) over the age of 60 (average age 65) with atherosclerosis.

Etiologies

  See detailed article: Arterial aneurysms

Their causes are the same as for any aneurysm, but they are of atherosclerotic origin in the vast majority of cases.

Clinical presentation and natural history

They are asymptomatic in more than one-third of cases and are discovered during an evaluation for another arterial aneurysm or through the palpation of a popliteal mass (however, more than half of these aneurysms are not palpable), which may be pulsatile, or through asymmetry in peripheral pulses during a clinical examination.

In other cases, they are discovered due to an acute complication (++ acute ischemia of the lower limbs), less frequently chronic.

Without treatment, the aneurysm diameter typically grows by 1.5 to 4 mm per year, and the risk of complications is 60 to 75% per year for aneurysms with a diameter greater than 2 cm.

Complications and associated conditions

  See detailed article: Abdominal aortic aneurysms (AAA)

See the detailed article: Acute ischemia of the lower limbs.

The most common complication: thrombosis and peripheral embolization with the risk of acute ischemia in the lower limbs. Other aneurysmal complications (rupture, compression, venous thrombosis, infections, etc.) are rare.

Additionally, there is a significant association (in ~50% of cases!) with the presence of an abdominal aortic aneurysm, which should always be investigated. The presence of other vascular lesions is common but varies depending on the underlying etiology.

Additional tests

The first-line examination remains Doppler ultrasound, with excellent sensitivity and specificity. If confirmed, an angio-CT scan or an angio-MRI of the lower limbs and abdomen should be performed to clarify the aneurysm's morphological characteristics and the condition of downstream arterial networks, as well as to rule out the presence of another aneurysm (++ abdominal aorta). The use of conventional angiography has become rare, except in cases requiring endovascular treatment.

Therapeutic management - Treatments

Screening and systematic treatment of cardiovascular risk factors. Specific etiological treatment if applicable. Management of complications (anticoagulation and/or revascularization in the case of acute ischemia of the lower limbs) and associated conditions as needed.

Surgical indications (exclusion with femoropopliteal vein graft):

• Symptomatic aneurysms
• Asymptomatic aneurysms if:
  • Aneurysm diameter > 2 cm
  • Presence of a parietal thrombus
  • Occlusion of downstream arteries

Given the limited experience in the field, endovascular treatment is only recommended in cases where surgery is contraindicated. It should, however, be discussed based on the expertise of the referral center.

In the absence of surgical indication: reevaluation and ultrasound monitoring once every 6 months.

Bibliography

EMC, Traité d'Angéiologie, 2018

Reed A, Popliteal artery aneurysm, UpToDate, 2024