The place of the leg accidentally knocked, if just a general skin abrasion, choose iodine pov sterilized clean, keep dry can be. If there is a slight wound, you can clean it and choose a band-aid to protect it. At the same time, need to prevent tetanus. If the wound is bigger and deeper, you need to consider going to the hospital in time. First of all, the local area needs to be cleaned, thoroughly stop bleeding, and suture the wound. After the suture need to adhere to the wound dressing, the general leg wounds need two weeks to remove the stitches. Secondly, after suturing the wound, timely give tetanus prevention, oral anti-inflammatory drugs to prevent infection. Keep the wound place dry and hygienic, insist on changing the dressing every two days or so.