In short, the ice machines did not work for me as well as ice packs.

If you're interested, here are details of what did & didn't work for me:
I injured one knee and had to wait for the swelling to go down to have a total knee replacement. With the extra strain, I ended up injuring the other knee, but it would have to heal completely so I could have the first knee worked on. Knowing my shoulders were soon to follow, I felt investing in 2 ice machines with exchangeable sleeves for knees, shoulders , etc, would be ideal. I loved the idea of temperature settings, timers to turn on and off thru the night while I slept, and I didn't need to wake anyone or get someone to come help me change ice packs throughout the day. I bought one from Amazon with plenty of 4+ star reviews:
(https://www.amazon.com/dp/B08FM8K3PW?ref=ppx_pop_mob_ap_share).

However, even with all the conveniences, and following the ideal settings & frozen bottle recommendations, my knee caps were too hot in the mornings to safely bear weight. So I would still have to use a frozen ice pack. ("Equate Reusable Hot or Cold Small Compress" from Walmart.com work for me for years).

While I may use an ice machine in the future for my shoulders (that don't need to bear weight), I returned both ice machines.
For a similar price, I bought a small freezer ("Arctic King" 1.0 cubic ft at Walmart.com) and I keep it in my nightstand. It actually hard freezes the ice packs better than our larger freezer.

I recommend you try whichever option you choose beforehand.