I have the Breg Polar Care Cube--it was on my leg when I woke up in recovery and came home with me. If your hospital has a similar arrangement keep after them to keep putting ice in it--they were sloppy about this at our local hospital. It has been a Godsend. I am still using it daily. (Its a cold day so I'm not running it this minute but have used it this morning.) They are pricey on Amazon ( I checked out of curiosity, wondering just how much insurance had forked over for it) but worth it in my opinion. If your knee is like mine you will go through a lot of ice, so MAKE SURE your home icemaker is up to the task, since you will be melting that ice with your nice hot knee 24/7 for a while at lest. We had to buy bag ice every couple of days for several weeks so we could also have ice for us. I'd buy some ice if you have room in your freezer (or on your back porch depending on your climate) anyway since icemakers can go on the fritz. You just dont want to run out. For me ice and elevation have been MORE important than opiates for pain reliief. I've only taken a half of a lortab so far in 2014, but I've run through some serious ice.
Nowadays, a little over 2 months out, I can fill it in the morning early, ice several times during the day, go to work at 4PM and still have a low enough temperature in it for it to work for me even though its midnight and the ice has long since melted. I would buy stock in Breg in a heartbeat. If your knee is aching because you've been out and about or went at PT too enthusiastically you will just sigh with relief as soon as that cold water starts circulating in the wrap.
I know others dote on the Cryo Cuff but I loooooove my Polar Cube. I have even fallen asleep with it going.