Weak or absent popliteal arterial pulsations can be caused by many reasons, and if they are not clearly differentiated, they can be misdiagnosed, affecting the entire treatment process and even threatening people’s lives. Therefore, we must pay attention to the identification of popliteal artery pulsation. Let’s take a look at some of the diseases that need to be differentiated. According to the history of trauma, fracture type and characteristics, clinical manifestations, it is generally not difficult to make a diagnosis, individual diagnostic difficulties can be selectively used CTA or arteriography. Elevation of the affected limb and drop test: Elevate the affected limb for 1-2min to observe the color change of the plantar skin. In patients without vascular lesions, the soles of the feet remain pink; if the patient has atherosclerotic occlusion and insufficient collateral circulation, the soles of the feet are pale white. In patients without vascular lesions, the color of the plantar surface remains pink; in patients with atherosclerotic occlusion and insufficient collateral circulation, the color of the plantar surface is pale; if it turns pink after exercise, the lesion is not too serious. The patient was asked to sit up and lower the limbs, and the filling time of the dorsal veins and the redness of the feet were observed. In normal people, the filling time of veins is within 20s, and the reddening time is within 10s. If the collateral circulation is insufficient, the venous filling time and redness time will be prolonged. If the reddening time of the limb does not recover within 15s, it is moderate ischemia; if it does not recover within 30s, it is obvious ischemia; if it does not recover within 60s, it is severe ischemia. This test should be performed in a warm room. It is of no value in the presence of varicose veins.