Popliteal artery entrapment syndrome
Popliteal artery entrapment syndrome (PAES) refers to symptomatic compression or occlusion of the popliteal artery due to a developmentally abnormal positioning of the popliteal artery in relation to its surrounding structures such as with the medial head of gastrocnemius (MHG) or less commonly with popliteus or fibrous bands.
The anatomic anomalies may be seen in up to 3-3.5% of the population and are often bilateral 2 (~2/3 of cases). Most individuals; however, are asymptomatic, and the true clinical syndrome is far less common. Individuals with well-developed muscles are more likely to be symptomatic, which probably explains why the syndrome is most often found in young sports persons (~60 % in those <30 years) with a male to female ratio of 15:1 3.
Symptoms are typically those of intermittent claudication. Physical examination can reveal signs of arterial compromise, particularly when the ankle is plantarflexed. Chronic repeated arterial compression can lead to acute thrombus formation and presentation with acute limb-threatening ischaemia in those with poorly developed collateral vessels.
Arterial compression can result in chronic vascular microtrauma, local premature arteriosclerosis, and thrombus formation. This can result in distal ischaemia. Stenosis and turbulent flow may lead to post-stenotic ectasia or aneurysm formation.
Five anatomic types of entrapment are typically described 1:
- type I: popliteal artery has an aberrant medial course around medial head of gastrocnemius
- type II: artery is not displaced, but the medial head of gastrocnemius inserts more lateral than usual; the artery passes medial and beneath the muscle
- type III: an accessory slip of medial head of gastrocnemius slings around the artery
- type IV: artery lies deep in popliteal fossa entrapped by popliteus or fibrous band
- type V: both popliteal artery and vein are entrapped
Another method of classification is the Heidelburg classification system 9.
- type I: the popliteal artery has an atypical course
- type II: the muscular insertion is atypical
- type III: both conditions are present
May show arterial compression elicited by manoeuvres such as plantar flexion and dorsiflexion 5. Doppler may demonstrate an increase in peak velocity 8.
CT / CT angiography
CT angiograpy can help identify an abnormal tendinous or muscular structures, diastasis between the popliteal artery and vein, an insertion anomaly and/or arterial deviation. Aberrant muscular and fibrous attachments can be different in almost every case and it best evaluated on axial images.
MRI is the best imaging modality to demonstrate the underlying anatomic type of entrapment, which helps guide surgical management 4. A medial slip of the medial head of the gastrocnemius may be seen, compressing the popliteal artery.
Lower limb angiography usually demonstrates medial deviation/compression of the popliteal artery when the ankle is plantarflexed. Occlusion of the vessels with thrombus can be seen in the acute presentation. Usually, collateral vessels are present. Even slight irregularity of the vessel can indicate a degree of entrapment 2.
Treatment and prognosis
Acute limb-threatening thrombosis requires urgent bypass surgery. Intermittent occlusion can usually be cured with the release of the popliteal artery alone or with saphenous vein bypass 2.
Imaging differential considerations include:
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- 6. Müller N, Morris DC, Nichols DM. Popliteal artery entrapment demonstrated by CT. Radiology. 1984;151 (1): 157-8. Radiology (abstract) - Pubmed citation
- 7. Hai Z, Guangrui S, Yuan Z et-al. CT angiography and MRI in patients with popliteal artery entrapment syndrome. AJR Am J Roentgenol. 2008;191 (6): 1760-6. doi:10.2214/AJR.07.4012 - Pubmed citation
- 8. Elias DA, White LM, Rubenstein JD et-al. Clinical evaluation and MR imaging features of popliteal artery entrapment and cystic adventitial disease. AJR Am J Roentgenol. 2003;180 (3): 627-32. AJR Am J Roentgenol (full text) - Pubmed citation
- 9. Radonić V, Koplić S, Giunio L, Bozić I, Masković J, Buća A. Popliteal artery entrapment syndrome: diagnosis and management, with report of three cases. Texas Heart Institute journal. 27 (1): 3-13. Pubmed
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The knee is a complex synovial joint that can be affected by a range of pathologies:
- bone and cartilage
- distal femoral condyle fracture
- tibial plateau fracture (classification)
- patella fracture
avulsion fractures of the knee
- Segond fracture
- reverse Segond fracture
- anterior cruciate ligament avulsion fracture
- posterior cruciate ligament avulsion fracture
- arcuate complex avulsion fracture (arcuate sign)
- biceps femoris avulsion fracture
- iliotibial band avulsion fracture
- semimembranosus tendon avulsion fracture
- Stieda fracture (MCL avulsion fracture)
- patella fracture
- chronic avulsion injuries
- chondromalacia patellae
- osteoarthritis of the knee
- osteochondral defects
- osteochondritis dissecans of the knee
- pattern of bone contusion in knee injuries
- knee fractures
- meniscal lesions
- synovial lesions
- fat pad
- popliteal fossa