1. Hands Are the Area You Forget Until You See a Photograph
Most people do not study the backs of their hands. They notice them by accident, in a photograph where the face looks exactly as intended and the hands holding the glass do not match it. That mismatch is the honest reason hand filler exists as a service rather than a novelty.
The gap is real and it is common. Someone can invest steadily in the face for years, keeping lines soft and volume where it belongs, while the hands receive nothing at all and quietly read a decade older. Faces get sunscreen, serums and appointments. Hands get soap, sunlight and a steering wheel.
What changes there is specific. The back of the hand carries very little fat to begin with, and that thin layer thins further with age, so the structures beneath it stop being covered. Tendons begin to stand out as cords, veins sit higher in relief, and the spaces between the long bones start to look hollow.
The skin above that layer is changing at the same time and for a different reason. Recognizing that those are two separate processes is the most useful thing a patient can bring to a hand consultation, because only one of them is a filler problem.