If you have an injured shoulder, you're gonna have to be careful about these two, if you choose to do them. Too many people involve their delts in these movements.
A good solution, for the barbell curls, is to lean forward about 10-15 degrees. If you keep that position, it will be almost impossible to use the shoulders. Really forces you to be strict.
I would also use preacher curls.
Good luck with the injury.