Adding banded tension to your shoulder work is guaranteed to trigger new hypertrophy gains. Just grab a couple of resistance bands and wedge them under the bench for overhead dumbbell presses.
The key is to lift the dumbbells all the way up to the top and hold them there for a couple of seconds in the contracted position of each rep.
When you have knee or shoulder issues, this is a good alternative to a standard squat. This is the touch-and-go version with chains for overload at the top.