A 62-year-old woman with a 30-year smoking history and poorly controlled diabetes mellitus presents with claudication in her lower limbs. Duplex ultrasound and angiography reveal atherosclerotic plaques in multiple peripheral arteries. Which arterial segment is the most common site of atherosclerotic involvement in the lower extremities?

Explanation

## Most Common Site of Lower Extremity Atherosclerosis **Key Point:** The superficial femoral artery (SFA) is the most frequently affected arterial segment in lower extremity atherosclerotic disease, accounting for approximately 40–50% of significant stenoses and occlusions in peripheral arterial disease (PAD). ### Anatomical and Hemodynamic Factors The SFA is preferentially involved because of: 1. **Longest segment** — extends from the adductor canal to the popliteal artery, providing the longest vascular territory in the lower limb 2. **Hemodynamic stress** — experiences significant shear stress and turbulent flow patterns, particularly at the adductor canal where the vessel narrows 3. **Chronic mechanical trauma** — subject to repeated compression and flexion during ambulation, promoting endothelial injury 4. **High-flow vessel** — carries the bulk of blood supply to the lower limb, similar to LAD in coronary circulation ### Frequency of Involvement by Arterial Segment | Arterial Segment | Frequency in PAD | Clinical Presentation | | --- | --- | --- | | Superficial femoral artery | 40–50% | Claudication, thigh/calf pain | | Popliteal artery | 15–25% | Claudication, critical limb ischemia | | Iliac artery | 20–30% | Hip/buttock claudication, erectile dysfunction | | Anterior tibial artery | 10–15% | Foot claudication, rest pain | **High-Yield:** SFA stenosis is the single most common lesion in symptomatic PAD. Combined SFA and popliteal disease is the most frequent pattern in advanced disease. ### Clinical Pearl SFA occlusion is often well-tolerated due to collateral circulation through the profunda femoris artery, which may explain why some patients with SFA occlusion remain asymptomatic or have mild symptoms. However, SFA stenosis (rather than occlusion) typically causes claudication because the stenosis limits flow during exercise. **Mnemonic:** **SFA = Superficial, Frequently Affected** — the superficial femoral artery is the most superficial and most frequently diseased segment in lower extremity PAD.