Is it permissible to surgically prevent menstruation for a 17-year-old mentally disabled girl, especially since she cannot distinguish the rulings of ritual purity from menstruation?

Whoever is responsible for the care of a girl must protect her. It is not permissible to perform a surgical procedure on the uterus to stop her menstrual cycle, because its harm outweighs its benefit. It may prevent childbearing, and it involves exposing the 'awrah (private parts) without necessity. She can be cleaned from the effects of menstruation by other methods that do not harm her, such as using pills. It is known that a mentally incapacitated person is not religiously obligated.