summary Popliteal artery entrapment syndrome is a condition characterized by constriction of the popliteal artery by adjacent muscles, tendons or fibrous tissue. Diagnosis can be suspected clinically with diminished pulses with active foot plantar flexion or passive foot dorsiflexion and confirmed with a lower extremity arteriogram. Treatment is generally conservative for mild symptoms with vascular surgery indicated for patients with refractory symptoms. Epidemiology Demographics male predominance (about 4:1) patient age typically 25-40 years old Etiology Mechanism typically due to underlying anatomic abnormality Pathophysiology decreased blood flow distal to the popliteal fossa leading to signs and symptoms consistent with compartment syndrome Classification and Anatomy Modified Whelan Classification Type I Medial head of the gastrocnemius is normal but the popliteal artery runs in an aberrant course Type II Medial head of the gastrocnemius is located laterally, no deviation of popliteal artery Type III There is an abnormal muscle bundle from the medial head of the gastrocnemius that surrounds and constricts the popliteal artery Type IV Popliteal artery is entrapped by the popliteus muscle Type V Popliteal vein is entrapped with the popliteal artery in any of the above scenarios Presentation Symptoms swelling patients often report limb swelling as primary complaint paresthesias foot numbness and paresthesias also common tingling sensation of toes following vigorous exercise cramping calf cramping following even light exercise as the condition worsens limbs can occasionally be asymptomatic Physical exam diminished pulses with active foot plantar flexion or passive foot dorsiflexion coolness of posterior calf and paresthesias may also be present can easily be confused with posterior compartment syndrome Imaging Radiographs usually normal Doppler ultrasound less invasive than arteriogram useful during physical exam to detect changes in pulse when active plantar flexion or passive dorsiflexion is performed Arteriogram used to confirm diagnosis close to 100% sensitivity will show stenosis, obliteration and post-stenotic dilation MRI/MRA and CT/CTA studies ongoing to evaluate usefulness for detection of popliteal artery entrapment Treatment Nonoperative activity modification and observation indications mild symptoms with rigorous exercise only Operative vascular bypass with saphenous vein vs endarterectomy indications if damage to the popliteal artery or vein most patients eventually require surgery technique can perform posterior or medial approach to popliteal fossa posterior approach provides improved exposure medial approach used more when bypass is indicated structures released depend on the type of entrapment Complications Surgical failure 30% rate of return of entrapment can result in need for amputation Wound infection <5% DVT around 10% Prognosis 70-100% of patients are reported to be asymptomatic after surgery