A 62-year-old man with a 40-year smoking history presents with claudication of the right lower limb. Duplex ultrasonography confirms peripheral arterial disease. What is the most common site of atherosclerotic lesions in lower limb peripheral arterial disease?

Explanation

## Most Common Site of PAD in Lower Limbs **Key Point:** The superficial femoral artery (SFA) is the most common site of atherosclerotic occlusion in lower limb peripheral arterial disease, accounting for approximately 40–50% of all lower limb lesions. ### Anatomical Distribution of PAD Lesions | Site | Frequency | Clinical Presentation | Notes | |------|-----------|----------------------|-------| | **Superficial femoral artery** | 40–50% | Claudication (calf/thigh) | Most common; often segmental | | Iliac artery | 20–30% | Claudication (hip/buttock) | Associated with erectile dysfunction (Leriche syndrome) | | Popliteal artery | 10–15% | Claudication (calf) | Often associated with SFA disease | | Anterior/posterior tibial arteries | 10–15% | Severe claudication/rest pain | Usually in advanced disease | **High-Yield:** The SFA is particularly prone to atherosclerosis because it is a muscular artery with high shear stress and turbulent flow at the adductor hiatus, where it passes through the adductor canal. This anatomical narrowing predisposes to plaque formation. ### Clinical Pearl The **aortoiliac** segment (iliac + distal aorta) is the second most common site. Lesions here present with **Leriche syndrome** (claudication of hip, buttock, and thigh with erectile dysfunction). However, when considering the **femoral-popliteal-tibial** (femoropopliteal) segment alone, the SFA dominates. ### Why SFA is Most Common 1. **Hemodynamic factors**: High-velocity flow and shear stress at the adductor hiatus 2. **Anatomical narrowing**: Passage through the adductor canal creates a natural stenosis point 3. **Segmental nature**: Often presents as a single long segment of occlusion ("SFA occlusion") 4. **Age-related changes**: Progressive atherosclerosis in this muscular artery with advancing age and smoking **Mnemonic:** **AFT** — **A**ortoiliac (20–30%), **F**emoral (SFA, 40–50%), **T**ibial (10–15%). The femoral segment is in the middle and is the most common. [cite:Robbins 10e Ch 11]