Knee scrapes generally heal in a few days depending on the extent of the injury. If the knee has suffered very little external force and the minor trauma is limited to the epidermal layer of the skin, it may heal in about 3 days. If it is more serious, it may take about 2 weeks to heal. A particularly severe abrasion, with a large and deep wound, may take 3 weeks or more to heal. Very minor wounds, almost no bleeding, generally the edge of the full layer of skin and subcutaneous tissue to the center of the wound, the wound can gradually reduce until the healing time takes about 3 days; if the knee abrasion is more serious, the wound localized with varying degrees of tissue damage and bleeding, it may take about 2 weeks to get better. This kind of abrasion within a few hours will appear inflammatory reaction, the blood in the wound and the exuded fibrinogen coagulation to form a clot, and then appear scab, the wound inside gradually grows granulation tissue, the epidermis also gradually shrink healing, until the granulation tissue completely fill the wound, the epidermis also completely cover the injury site, can be considered good, this process takes about 2 weeks; if the abrasion is particularly serious, the wound is larger or deeper. If the scrape is particularly serious, the wound is large or deep, you need to seek medical attention to clear the wound, you may need to play tetanus vaccine, because the wound is larger, the granulation tissue to fill the wound and epidermal coverage requires more time, it may take about 3 weeks to good. For milder knee abrasions, the patient can disinfect the wound by drawing concentric circles with iodophor and a sterile cotton swab centered on the wound. If the wound is very shallow and exudes very little, it can be left to dry directly after disinfection and wait for the wound to scab; if the wound is larger and exudes or bleeds more, medical attention is needed for debridement, disinfection, and dressing treatment.