You shouldn't ice for longer than 20 minutes due to the risk of freezing your skin (even when using a towel as protection) which can result in skin and nerve damage. I must say I didn't know that at my first surgery so I definetly iced way longer. I think my knee is very used to the icing. I am icing at least twice a day (after lunch and before bedtime). I sleep with my icemachine that activates every 80 to 100 minutes for 10 minutes, sleepsaver!Ice is your friend! Ice for 45 - 60 minutes several times per dayUnfortunatly my knee will react afterwards and be sore/hurts the rest of the day