What is a characteristic of popliteal artery aneurysms?

Characteristics of Popliteal Artery Aneurysms

Popliteal artery aneurysms are often bilateral, occurring in approximately 50% of affected patients, and frequently result in limb ischemia due to their high rate of thromboembolic complications. 1

Epidemiology and Prevalence

• Popliteal aneurysms account for 70% of all peripheral aneurysms in the lower extremities 1
• Estimated incidence of 0.1% to 2.8% in the general population 1
• Predominantly affect men, with a strong male predominance 2, 1
• Popliteal aneurysms are MORE common than femoral aneurysms (not less common as suggested in option A) 2

Bilateral Occurrence

• Approximately 50% of popliteal aneurysms are bilateral 2, 1
• This bilateral nature is an important diagnostic clue when evaluating patients with acute limb ischemia
• The presence of a prominent popliteal pulse in the opposite leg can help identify the underlying etiology of acute ischemia 2

Gender Distribution

• Popliteal aneurysms predominantly affect men 1
• In one study, 59 out of 61 patients (97%) with popliteal aneurysms were men 3
• They are NOT more common in females (contradicting option C)

Complications and Limb Ischemia

• Popliteal aneurysms frequently result in limb-threatening ischemia 2, 1, 3
• Thrombosis occurs in approximately 39% of cases, most often in larger aneurysms 2
• Thrombosis of popliteal arterial aneurysms accounts for approximately 10% of acute arterial occlusions in elderly men 2
• Severe ischemia usually occurs because:
  • Thrombosis happens suddenly without collateral enhancement
  • The popliteal artery is the sole axial artery traversing the knee 2
• 36% of patients with observed popliteal aneurysms develop complications 1
• Cumulative incidence of ischemic complications reaches 70% during 5-10 years of follow-up 1

Natural History

• Asymptomatic popliteal aneurysms have a high rate of becoming symptomatic:
  • 50% become symptomatic within 2 years of discovery
  • 75% become symptomatic within 5 years 1
• The probability of developing complications increases with time to 74% within 5 years 4
• Growth rate is approximately 1.5 mm per year for aneurysms >2.0 cm and 0.7 mm per year for aneurysms <2.0 cm 1

Management Recommendations

• Surgical indications include:
  • All symptomatic aneurysms
  • Asymptomatic aneurysms ≥2.0 cm in diameter 2, 1
• Annual ultrasound monitoring is recommended for asymptomatic aneurysms <2.0 cm 1
• In patients with acute ischemia and absent runoff, catheter-directed thrombolysis or mechanical thrombectomy should be considered 2, 1

Common Pitfalls

• Mistaking thrombosed popliteal aneurysm for an embolic event 2, 1
• Failing to screen for contralateral popliteal aneurysms and abdominal aortic aneurysms 1
• Delaying treatment of asymptomatic aneurysms ≥2.0 cm 1
• Ultrasound is the initial diagnostic test of choice for popliteal aneurysms 1

In conclusion, popliteal artery aneurysms are more common than femoral aneurysms, often bilateral, predominantly affect men, and frequently result in limb-threatening ischemia due to thromboembolism.