Is it permissible for a sister to expose her knee to her brother if it is broken?

A woman's 'awrah (parts that must be covered) in front of her mahram (unmarriageable kin) is her entire body except for what is customarily uncovered, such as the face, hair, neck, forearms, and feet. Therefore, it is not permissible for a woman to uncover her knee in front of her brother except out of necessity or need, such as for medical treatment and the like. Sheikh Sulaiman Al-Majid stated that it is not permissible for a woman to expose her knee in front of other women or mahram due to the potential harms involved. However, if there is a need to treat her knee and her brother is a doctor or is the only one available, then it is permissible at that time.