Popliteal artery entrapment syndrome

The popliteal artery entrapment syndrome (PAES) refers to symptomatic compression or occlusion of the popliteal artery due to a developmentally abnormal relationship with the medial head of gastrocnemius (MHG) or less commonly with popliteus. Arterial compression can result in chronic vascular microtrauma and local premature arteriosclerosisand thrombus formation. This can result in distal ischaemia. Stenosis and turbulent flow may lead to poststenoticectasia or aneurysm formation.

Five anatomic types of entrapment are typically described ¹ :

• type I : popliteal artery has aberrant medial course around MHG (see case 1)
• type II : artery is not displaced but the MHG inserts more lateral than usual ;  the artery passes medial and beneath the muscle
• type III : accessory slip of MHG 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

Epidemiology

The anatomic anomalies may be seen in up to 3% 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

Clinical Presentationpresentation

Symptoms are typically those of intermittent claudication. Physical examination can reveal signs of arterial compromise particularly when the ankle is dorsiflexed. Chronic repeated arterial compression can lead to acute thrombus formation and presentation with acute limb-threatening ischaemia in those with poorly developed collateral vessels.

Radiographic Features features

Ultrasound

May show arterial compression elicited by maneuvers such as plantar flexion and dorsiflexion ⁵. On Doppler can be seen as a increase in peak velocity ⁸

Angiography / DSA

Lower limb angiography usually demonstrates medial deviation / compression of the popliteal artery when the ankle is dorsi or plantar flexed. Collateral vessels are often present. Even slight irregularity of the vessel can indicate a degree of entrapment ². 

MRI

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 chef of the gastrocnemius may be seen, compressing the popliteal artery.

Treatment and Prognosisprognosis

Acute limb-threatening thrombosis requires urgent bypass surgery. Intermittent occlusion can usually be cured with release of the popliteal artery alone or with saphenous vein bypass ².     

Differential diagnosis

Consider

• cystic adventitial disease of popliteal artery

See also 

• other vascular syndromes