When you have new knee pain, itâs best to apply ice. Cover your knee with a towel and place ice on it for 15 minutes at a time. At first, you can use it every hour for up to 15 minutes. After the first day, use it at least four times a day.hen you have new knee pain, itâs best to apply ice. Cover your knee with a towel and place ice on it for 15 minutes at a time. At first, you can use it every hour for up to 15 minutes. After the first day, use it at least four times a day.