Young's Modulus and Bone

I know that Young's modulus should increase when bone growth happens but can someone explain using the equation what is happening?

Here is my attempt:

Y = (F/A)/(delta l/l)

When we are building bone, the ability of the bone to generate restoring force should increase - F increases
delta l should also be positive

So are we saying that F increases more than delta l and so there is a new increase in Y


Also, another question - Is stress scalar or tensor? I have some across sources...

Young's Modulus and Bone