Ask an expert
The first thing you should do before you go out to buy an icepack is to talk to an expert. Going on to meeting with a doctor and then consulting them over what style of icepack to use will end up proving to be rather helpful.
Not only would they be able to recommend something made specifically for your injury, but they might even be able to write you a note, which could make it a whole lot easier for you to acquire the icepack. At the same time, a note from the doctor will also ensure that your health insurance covers the cost of the ice pack.
You need to really focus on the determining the style of the icepack that you are looking to buy. The standard shoulder ice pack is designed to just hang over your shoulder. However, there are alternatives with straps and other things to secure them in place.
Now each style has its pros and cons, and it is going to be up to you to decide what it is that you are looking for in an ice pack.
Another smart move would be to try out how the ice packs feel when you are wearing them, so that you can get one you are most comfortable with.
Go to store
The last thing you need to do is to head on down to the stores that sell ice packs and then browse for the one that you want. If they have the one you want, pick it out and then go on and pay for it at the counter.
Make sure that you save the bill so that your insurance can cover it later on.