The replantation of severed fingers has developed to the terminal level, and in recent years, the success rate of replantation of severed fingers with various special complex injury types has increased significantly. In the replantation of severed fingers with various complex injuries, the complexity of the injured vessels is the key to determine the replantation method and whether it is viable, and there are very few detailed studies on the vascular injury conditions. It is generally believed that avulsed severed vessels cannot be used for anastomosis [1]. However, we found in our clinical practice that many non-excisional severed fingers had varying degrees of vascular injury, and successful replantation of severed fingers was achieved after preserving and anastomosing these vessels [2]. Therefore, we tried to use avulsed severed vessels for anastomosis in various severely injured severed fingers and achieved success, and also analyzed and summarized various types of severed vessels and corresponding surgical protocols to provide theoretical guidance for clinical application and achieve satisfactory results. Data and methods I. General data The group consisted of 53 cases with 58 fingers, 44 men with 48 fingers and 9 women with 10 fingers; age ranged from 16 to 52 years old, with an average of 38.6 years old. Reasons for injury: smash avulsion injury of 28 fingers, machine strangulation of 30 fingers. Fingers: 18 thumbs, 14 index fingers, 8 middle fingers, 12 ring fingers, and 6 little fingers. The plane of severance: 39 fingers at the terminal segment, 11 fingers at the middle segment, and 8 fingers at the proximal segment. We divided the vessels in the traumatic area of the severed finger into two parts: the free segment and the embedded segment. The free segment is in a free state with no surrounding tissues connected, and the outer membrane of the vessel is damaged to different degrees, which is caused by the extraction of the vessel from the proximal or distal end, so the length of the vessel in this segment is longer than that in its physiological state; the embedded segment is located in the soft tissue of the trauma area, and the vessel is still connected with the surrounding tissues. Due to the elastic retraction of blood vessels, part of the free segment vessels are covered by the soft tissue of the trauma area, and attention should be paid to the difference. The tissue around the vessels in the embedded segment often has hemorrhagic or bruise-like changes, and the vessels in this segment of tissue may have thrombus due to contusion. We measured the vascular length of the finger artery in the non-stretched state through the surgical microscope (8x), and the measurement of the embedded segment was based on the junction point between the traumatic and non-traumatic areas of the severed finger to the root of the free zone of the vessel. The length of the free segment was 0.15cm~2.5cm, with an average of 1.1cm; the length of the embedded segment was 0.5cm~2.0cm, with an average of 1.3cm. In general, the free segment of the venous vessels was shorter. The procedure is performed under brachial plexus anesthesia or finger root nerve block anesthesia, and the bleeding is stopped by balloon tourniquet or finger root rubber tourniquet. After routine debridement, the finger bone is repositioned with internal fixation of the Kirschner pin, and then the vessel is debrided under the microscope, the length of the vessel is measured and recorded, and the feasibility of surgical reimplantation is analyzed and the surgical plan is decided: as long as the proximal vessel lumen is round and elastic under the microscope, the broken end is cleared and blood is continuously spilled, and there is no obvious flocculent material in the lumen of the broken finger, anastomosis can be used; if there is no anastomosis at the distal end of the same side, cross-vessel anastomosis is used to solve the problem If there is no anastomosis on both sides of the proximal end, the method of transposition of the artery of the adjacent finger is used; if the apical plane of the finger is severed, if the proximal end of the severed plane is particularly close to the vascular arch, the bifurcated segment can be excised for end-to-end anastomosis, and the same caliber branch can be anastomosed, with attention to suturing other breaks; in some cases, the vascular exfoliation-like changes are obvious, the structure of the vascular cavity is completely stripped from the outer tissue, and the vessel is transparent and brittle, so it is easy to tear when suturing. If there is tension between the vessels, the outer layer of the vessel must be sutured together to prevent the vessel from tearing during or after suturing. In general, the free segment of the vein is short, and the severed finger has sufficient length for anastomosis after appropriate shortening. In this group, ipsilateral direct anastomosis of 19 fingers resulted in the survival of 16 fingers; cross-vessel anastomosis of 31 fingers resulted in the survival of 27 fingers, arterial transposition of adjacent fingers and avulsion vascular anastomosis of severed fingers resulted in the survival of all 3 fingers, and graft vascular repair of 5 fingers resulted in the survival of one finger. The length of the avulsed free segment of the vessel exceeded 2 cm in 5 cases, and 3 cases survived, among which 1 case had a critical arterial phase 3 days after surgery and was not explored surgically, and the other case resumed blood circulation 8 hours after surgery but eventually necrosis after 3 days. Among them, those with irreparable nerve avulsion had thin and small fingers, and some of the severed fingers were obviously thinner and had poor sensory recovery; while those with anastomosed nerves had satisfactory recovery of appearance and sensory function, among which early functional exercise and participation of workers were the best recovery. Discussion I. Selection of indications and their significance Not all avulsed severed vessels can be used in the replantation of severed fingers, and we must strictly grasp their scope of application. Generally speaking, whether a vessel can be used or not is mainly based on what is seen under the microscope. If the proximal vessel lumen is round and elastic, if there is constant blood spillage after removal of the severed end, and if there is no obvious flocculent material in the lumen of the vessel on the severed finger, the anastomosis can be used. However, it should be used with caution for type III avulsed vessels with a free segment length of more than 2 cm. And for those who have obvious vascular defects or no anastomotic artery on the side of the severed finger, it is recommended to abandon the use of vascular grafting or venous arterialization for reimplantation. In the case of non-primary functional fingers such as the ring little finger, the use of arterial transposition of the adjacent finger is not recommended if there is no proximal anastomotic artery, but it is indicated for the thumb and index finger. The use of avulsed vessels for replantation not only expands the range of indications for replantation, but also avoids new injuries caused by the use of vascular grafts and other methods used to address vascular defects. It also provides another attempt for the in-depth research of finger reimplantation. 1. Since the blood vessels in the free segment of the severed finger are soft and collapsed, there is no residual blood in the lumen after debridement, so it is not easy to find them, so they should be searched carefully under 8~10 times surgical microscope with the nerve as the marker in its inherent anatomical part. The terminal severed finger needs to be anastomosed under 16x microscope. 2.Vessels located in the soft tissue of the embedded segment may have contusions, whether the vessels in this part need to be explored should be based on the following points: with a tourniquet, if there is continuous bruising out of the proximal vascular fracture after debridement, or if there is continuous spillage of fresh blood under a loose tourniquet, exploration is not required; the observation under the operating microscope on the side of the severed finger does not require exploration if there is no obvious bleeding area around the vessel when it is free to the depth. Even when performing vascular exploration, note that it is not necessary to completely free to reveal the full length of the vessel, through a longitudinal entrance can determine the vascular damage. 3.When the free segment is long, there is no supporting protective tissue around the vessel, and at the same time, there are different degrees of injury to the outer membrane of the vessel, so vasospasm is likely to occur, while the embedded segment is embedded in the injured tissue, and postoperative tissue swelling and inflammatory reaction stimulation will also have adverse effects on the vessel. Therefore, we routinely use poppy bases for intraoperative closure and local spraying around the proximal artery. Postoperatively, we routinely use “triple anti” therapy and “mannitol” dehydration therapy, and massage the severed finger at the same time. 4.Vessel damage in avulsion dissection is serious, and thrombosis is easily formed after anastomosis. Especially, it is difficult to determine the degree of intimal damage even under the microscope. Therefore, in the absence of a reliable method of intraoperative judgment, the use of avulsed vessels should be used with caution.