HA augmentation to the forehead

Hi! I am an aesthetic / plastic surgeon in Japan.
I have recently experienced a case of a woman with HA injection to the forehead
from a clinic in Los Angeles, California USA.
Just after 3 months, she found 3 lumps in the forehead.

She claimed that they injected HA to her forehead only 3 times through the skin.

I think the aesthetic surgeons in LA injected HA into the sub-dermis.
I always inject HA between the periosteum and the frontal bone.

How do you inject HA for forehead augmentation?

Thanks 🙂