Please talk with your doctor, he has probably the best answer for you. it is allways hard to give advice because we don't no the intensity of your injury.
You have to leep in mind that your hands are both the most mobile and they are also the point which has to deal with a lot of pressure when you you workout your upper body - in short - you use your hands a lot. Talk to a physiology trainer, i am pretty sure after your sugery you have to do some physiotherapy.
I would recommed you to go swimming.
Don't start to early with upper body exercises, it would be very sad if you hit them to hard and to early - it will just causes a longer break again!
However you don't have to lose the motivation:-D Can you do pistol squads? If no, tadaaa, here is your new goal for the month you can't workout your upper body probably :-)
Like allways, step by step Terminator
salute from germany!