We had this last year. DS (14) broke his, but right in the middle of the bone. It was a complete break, and the two parts of the bone overlapped, so they had to operate and put a plate in. Probably not as complicated as your ds's, as it didn't involve any ligaments.
The operation went smoothly, he was out in a few hours. A lot of pain from the op, but the bone itself stopped hurting straight away.
I propped him up with pillows, and changed his bed so that he slept on his good side.
Chair by the bed to help him pull himself up to sitting.
Get some old fashioned bandage to make slings you can use in the shower and get wet.
He had a super sling for around 6 weeks. Lunch and corridor pass for school, to get out of class early. Friend to carry school bag.
Physio afterwards, and it did take time to get strength back. He also had a specialist massage/acupuncture session after a couple of months, as he was pulling muscles doing sport without enough flexibility.
PM me if you like.