The popliteal artery entrapment syndrome (PAES) is an uncommon pathology that occurs when the popliteal artery is compressed by the surrounding popliteal fossa myofascial structures. This results in claudication and chronic leg ischemia. This condition mainly occurs more in young athletes than in the elderly. Elderly people, who present with similar symptoms, are more likely to be diagnosed with peripheral artery disease with associated atherosclerosis. Patients with PAES mainly present with intermittent feet and calf pain associated with exercises and relieved with rest. PAES can be diagnosed with a combination of medical history, physical examination, and advanced imaging modalities such as duplex ultrasound, computer tomography, or magnetic resonance angiography. Management can range from non-intervention to open surgical decompression with a generally good prognosis. Complications of untreated PAES can include stenotic artery degeneration, complete popliteal artery occlusion, distal arterial thromboembolism, or even formation of an aneurysm.
History In 1879, the syndrome was first described in a 64 years old male by Anderson Stuart, a medical student. In 1959, Hamming and Vink first described the management of the PAES in a 12-year-old patient. The patient was treated with myotomy of the medial head of the gastrocnemius muscle and concomitant endarterectomy of the popliteal artery. They later reported four more cases and claimed that the incidence of this pathology in patients younger than 30 years old with claudication was 40%. Servello was the first to draw attention to diminished distal pulses observed with forced plantar- or dorsiflexion in patients with this syndrome. In 1981, Bouhoutsos and Daskalakis reported 45 cases of this syndrome in a population of 20,000 Greek soldiers. Over the last few decades, the increasing frequency with which popliteal artery entrapment is reported, strongly suggests greater awareness of the syndrome.
Epidemiology In the general population, popliteal artery entrapment syndrome (PAES) has an estimated prevalence of 0.16%. It is most commonly found in young, physically active males. In fact, sixty percent of all cases of this syndrome occur in athletically active males under the age of 30. The predilection of this syndrome presents in a male to female ratio of 15:1. This discrepancy in prevalence may be overestimated due the findings that males are generally found to be more physically active than females or because a large portion of the data is from military hospitals that treat mostly male populations. Functional PAES, the more common variant, tends to skew towards young, physically active females. People, who participate in running, soccer, football, basketball, or rugby, are at increased risk. Newborns and young children are also at increased PAES risk due to congenital causes. During embryonic development, the medial head of gastrocnemius migrates medially and superiorly. This migration can cause structural abnormalities, such as irregular positioning of the popliteal artery, and can account for the rare instances of entrapment caused by the popliteus muscle. Less than 3% of all people are born with this anatomical defect that progresses into PAES, and of those who are born with the anatomical defect, the majority never develop symptoms. Bilateral presentation of PAES is found in approximately 30% of cases.
Pathophysiology and classification PAES can be classified as either congenital or functional. Analysis of human embryological development has shown that the popliteal artery and the medial head of the gastrocnemius muscle arise at approximately the same time. Because of that, abnormal development of muscle's position in relation to the nearby vessels can result in potential vascular compromise. The varying types of PAES can be classified based on aberrant migration and resultant attachments of the medial head of the gastrocnemius muscle. Type VI PAES (functional PAES) describes a subtype that is due to repeated microtrauma resulting in the destruction of the internal elastic lamina and damage to the smooth muscles resulting in fibrosis and scar formation.
Additionally, a more practical classification system was introduced by Heidelberg et al. This system classifies PAES into three main types:
Type 1: The problem lies in the abnormal position of the popliteal artery. Type 2: The problem lies in the abnormal insertion of the medial head of the gastrocnemius muscle. Type 3: Both types 1 and 2 are present.
Medical history and physical examination Patients with PAES are typically healthy young males without previous history of cardiovascular risk factors such as smoking, hypertension, hypercholesterolemia, or diabetes. Typically, patients present with posterior intermittent claudication that is worsened with exercise and relieved with rest. Specifically, walking up stairs or inclines tends to be the strongest and most common trigger of PAES symptoms due to leg/knee positioning, flexion of the foot, and the groups of muscles being used. Associated symptoms include numbness, discoloration, pallor, and coolness in the affected lower extremity. Physical examination of suspected PAES may show hypertrophy of the calf muscles, as well as diminished, unequal, or absent pulses in the lower extremity upon plantar- or dorsiflexion.
Diagnosis
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