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Popliteal artery aneurysm and peripheral aneurysms
Popliteal artery aneurysm is the commonest peripheral aneurysm; it almost never ruptures, but tends to thrombose and embolise, causing acute ischaemia and amputation, so it is repaired from a diameter of 20 mm or when it contains thrombus or causes symptoms — and in every such patient an aortic aneurysm and a contralateral popliteal aneurysm are sought.
Why it matters in the exam
Popliteal aneurysms account for most peripheral aneurysms, almost only in older men. In about half of patients they are bilateral, and a substantial share also have an abdominal aortic aneurysm — so every patient with a popliteal aneurysm needs ultrasound of the aorta and the other popliteal artery, and vice versa. On examination a broad, "too strong" pulse is felt behind the knee. The danger is not rupture but thrombosis of the aneurysm or repeated emboli that silently occlude the calf arteries, until acute limb ischaemia appears with a high risk of amputation. So repair is preventive: according to SVS, an aneurysm of 20 mm or more, an aneurysm with thrombus inside, or a symptomatic aneurysm — is repaired.
The classic surgical approach is medial: ligation of the artery above and below the aneurysm and bypass with saphenous vein; the drawback is that the sac remains and may keep growing from side branches. In a posterior approach the sac is opened and the branches are sutured from inside, which suits a large aneurysm compressing the vein or nerve. A covered endovascular stent graft is an alternative in older or high surgical risk patients, with slightly lower patency. In acute ischaemia from a thrombosed aneurysm, the problem is that the calf arteries are already occluded by emboli: so catheter-directed thrombolysis is sometimes given first to "open" the calf arteries, and only then a bypass is done. A true femoral artery aneurysm is less common and also tends to thrombosis and embolism; a femoral pseudoaneurysm after catheterisation is a separate topic.
A subclavian or brachial artery aneurysm is sometimes linked to thoracic outlet syndrome, and is treated by the same principles of preventing thrombosis and embolism.
Key points
- The commonest peripheral aneurysm.
- Bilateral in about half; linked to aortic aneurysm.
- Repair from 20 mm or with thrombus.
- The danger — thrombosis and emboli.
- Acute ischaemia — thrombolysis then bypass.
Summary table
| Situation | Finding | Treatment |
|---|---|---|
| Asymptomatic popliteal aneurysm below 20 mm | Broad pulse behind the knee | Ultrasound surveillance |
| 20 mm or more or thrombus inside | Risk of thrombosis and emboli | Repair: ligation and vein bypass or stent graft |
| Large aneurysm compressing vein or nerve | Oedema or numbness | Posterior approach and opening of the sac |
| Acute thrombosis of the aneurysm | Acute ischaemia, occluded calf arteries | Thrombolysis then bypass |
| Every popliteal aneurysm | Search for further aneurysms | Ultrasound of the aorta and the other side |
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Sources
- ESVS Clinical Practice Guidelines on the Management of Abdominal Aorto-iliac Artery Aneurysms, 2024 — Associated peripheral aneurysms
- SVS clinical practice guidelines on popliteal artery aneurysms, 2022 — Indications and techniques of repair
- Rutherford's Vascular Surgery and Endovascular Therapy, 10th edition (2022) — Popliteal and femoral artery aneurysms
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.