A testicular prosthesis is a small implant with a size, shape, and consistency like a real testicle. It is usually made of a soft plastic (silicone) shell and filled with saline (salt water).
The risks of a testicular prosthesis include infection and bleeding or blood clots in the scrotum. But these problems are not common.
If a prosthesis is implanted before puberty, it will need to be replaced later with a larger prosthesis that matches the adult size of the normal testicle.