Improved results of surgical treatment of patients with critical ischemia of lower extremities can be obtained by using the collateral bed. The condition of the profound femoral artery and the popliteal artery, especially in the zone of its trifurcation, is of the greatest significance for the decision on the volume of surgery. The carrying capacity of the collateral bed of the profound femoral artery in occlusion of the femoral artery was on average 284 ml/min. A positive prognostic criterion of recovered circulation in the extremity using the profound femoral artery is preservation of the patent trifurcation of the popliteal artery and/or the anterior tibial artery. The blood flow volume along the profound femoral artery under the given functional-anatomical conditions should be not less than 150 ml/min. Semiclosed loop endarterectomy of the superficial femoral and popliteal arteries with multilevel lesions of the lower extremity arteries allows the main zones of the collateral bed of the femoro-popliteal-tibial segment to be included in the blood flow.