Cleaning a skinned knee immediately will promote faster healing because it will prevent infection. First the bleeding should be stopped by keeping pressure on the skinned areas with a clean rag or cloth. Next, the Mayo Clinic says the knee should be rinsed with water. Don't used soap, which can irritate the wound. If there is any dirt or particles stuck in the skinned parts of the knee, they can be removed with tweezers. This allows the healing process to start.
Once the skinned knee is cleaned, it can be medicated to prevent infection. This should be done during the first week of the injury. The Mayo Clinic says the best type of medication is an antibiotic ointment or cream. This will keep the skinned knee moist and discourage infection of the wound. Creams and ointments won't directly make a skinned knee heal faster, but they prevent delays in the healing process due to infection while white blood cells and platelets do their repair work.
Initially, the Mayo Clinic says a skinned knee should be bandaged because keeping it covered will protect it from infection. Once the wound has healed enough to keep bacteria out, which will take about a week or two, it should be left uncovered. At that point, being exposed to air will actually allow the skinned knee to heal more quickly. With this proper care, the skinned knee should be completely healed within four weeks as the platelets complete reconstruction of new tissue.