How to take care of my friend's son when he falls?

In this case, you can express your concern like this:

1. I heard that your son was injured, and I was really worried. I hope he will recover soon, and I hope you can get support and comfort at this time.

I know you must be worried at this time, but please trust the diagnosis and treatment of professional doctors. They will do their best to restore your son to health. I am always ready to help if necessary.