I'm 2 months in from shattering my kneecap and having to keep my leg elevated. I have been on my own for the majority of that time and these are the things that would really help/have helped from my personal experience.
If you can have them come stay with you or you stay with them particularly at the start it would make a big difference, but give space as early recovery is exhausting and painful.
Help with shopping, washing, food prep so a meal can be popped in the microwave to avoid having to stand for long.
If they are on their own and on crutches,, an across the body bag to transport essentials, pain killers etc. A cup with a screw top lid for drinks that can be popped in the bag.
A lap tray if unable to sit at a table, this can also be pushed along the floor if needed.
Company, check in when you can, even if just over the phone. It can get very lonely.
If unable to shower, large wet wipe type cloths.
Check what you can get aid wise free of charge, eg rails for the toilet, helps massively.