Traffic trauma as well as accidental injuries bring more and more injuries to the lower leg and foot and ankle. Because of their few local soft tissues and poor blood supply, once open fractures or crush contusions occur, skin soft tissue necrosis and defects are very likely to occur, resulting in the exposure of bone, tendons, nerves and blood vessels, making direct repair difficult. The application of peroneal nerve trophic flap transfer is an excellent tool for repairing such defects. The flap has the following advantages: 1, reliable blood flow, no damage to the main blood vessels of the lower leg, no need for anastomosis; 2, standardized surgical design and operation, easy to master; good texture of the flap, not bloated; 3, the flap contains sensory nerves, skin sensation can be restored after transfer, preventing pressure sores, so it becomes a good tool for repairing defects of the lower leg, foot and ankle. The case introduction is shown as follows: Figure|Real case of surgical defect repair Postoperative care: 1. 24 hours after surgery, closely observe the flap blood flow and pay attention to any flap pallor, bruising, swelling and bleeding in order to make timely treatment; 2. Elevate the affected limb 30 degrees above the heart level to facilitate the swelling to subside; 3. The tip of the flap transfer should not be pressed to avoid affecting the flap blood supply; 4. Change the external dressing on time within two weeks and do not unpack it so as not to affect the survival of the implant; 5. Postoperative treatment to prevent infection and improve blood flow is routinely given intravenously for 5-7 days; 6. The removal of stitches of the flap and implant is usually 14 days; 7. After the removal of stitches, the next treatment plan is decided according to the nature of the lesion, and if it is a tumor, it is recommended to visit the oncology department for the next treatment within one month after surgery; 8. Reduce weight-bearing on the affected limb, you can walk less with the aid of brace and elevate the affected limb more.