I. Early diagnosis of N artery injury Early diagnosis of vascular injury is the most important factor in shortening the time between vascular injury and revascularization and improving the prognosis. For open N artery injury diagnosis is generally not too difficult. However, for closed N artery injuries often focus only on the treatment of fracture dislocation and delay or even omit the diagnosis, thus losing the best time window to reconstruct the blood circulation of the injured limb, leading to irreversible consequences. Therefore, every patient with periprosthetic fracture dislocation should be alerted to the possibility of vascular injury, and repeated and careful clinical examination is the most critical step. Some scholars have pointed out the “hard signs” (diminished or absent distal arterial pulsation, arterial hemorrhage, gradually increasing hematoma, pulsatile hematoma, or contusion or bruising at the site of arterial injury) and the “soft signs” (distal destruction injury, large nonpulsatile hematoma, etc.). The “6P” symptoms of acute ischemia in the affected limb have been proposed as important reference indicators of N artery injury. The typical clinical manifestations of vascular injury are often not obvious, especially in patients with traumatic shock, so the authors believe that toe-end pulse oxygen monitoring of the injured limb can also be used as a reference indicator at this time. If the oxygen saturation of the toe is 0 or significantly lower than that of the healthy side of the same toe, N artery injury should be highly suspected, especially after the correction of shock, which is of clinical significance. The test is noninvasive, simple, and can be repeatedly performed, etc. It is believed that the detection of vascular signal changes in the injured limb still has a high specificity and sensitivity for the diagnosis of vascular injury, but the requirements for the operator are high. Second, combined with the characteristics of interventional treatment of N artery injury It is believed that imaging can delay the time of reconstructing blood circulation for 1 to 2 hours, and arteriography is not advocated for patients with obvious clinical manifestations of vascular injury, but immediate surgical exploration and repair. Because the injury of periprosthetic fracture dislocation combined with N artery is more insidious, the vascular injury is complicated, and the degree of vascular injury can continue to evolve after the injury. Although angiography is invasive, it is the most reliable method to diagnose vascular injury because it can accurately detect the site and extent of vascular injury, as well as the collateral circulation of the artery and whether it is combined with thrombosis. In the case of ruptured vessels with active bleeding, contrast spillage can be seen by hand pushing the angiogram; in the case of vascular embolism, contrast retention can be seen; in the case of localized occlusion, ultra-slip guidewire exploration can be seen by passing the guidewire through the ruptured part of the vascular wall to penetrate the bleeding vascular wall, and contrast spillage can be seen in the local vascular wall. The authors experienced that the surgical operation was performed simultaneously with the collaboration of the interventional department, which would not delay the time to reconstruct the blood circulation of the injured limb, but on the contrary could avoid the blindness of the surgical exploration, restore the blood flow of the injured limb and save the limb as early as possible. Spasm and re-embolization after anastomosis are related to strict microsurgical vascular anastomosis technique, but are more dependent on the severity of the primary injury and the availability of adequate soft tissue coverage around the anastomosed vessel. In addition, the stability or lack of stability of the fracture has an impact on it. Postoperative thrombolytic and anticoagulant therapy via indwelling catheter can, on the one hand, dynamically observe the patency of the anastomotic vessels; on the other hand, it can improve the stress hypercoagulable state of microcirculation and effectively reduce the chance of anastomotic vasospasm and re-embolization. Prophylactic deep fascial interval reduction The need for fascial interval reduction in the lower leg of the injured limb is controversial. Since N artery injuries are often the result of high-energy trauma, the muscle soft tissue contusions are more severe. Tissue edema can exacerbate further ischemia in the limb, impede veno-lymphatic system return, predispose to osteo-fascial compartment syndrome, and even reembolization of the anastomotic vessel. Tension reduction can stop the vicious cycle between limb ischemia and increased pressure in the interfascial compartment and reduce the reperfusion injury in the limb. Therefore, decompression by deep fasciotomy of the calf is a routine adjunct to the management of this type of injury. One case in this group did not undergo prophylactic calf fascia interval decompression in the early stage and was forced to undergo high level amputation after 1 week due to extensive calf muscle necrosis, which was a profound lesson. Further clinical studies are needed to determine whether the changes in interventional contrast flow before and after calf reduction are related to the degree of vascular injury and the duration of limb ischemia.