an insole which extends from the toes to the heel includes at least one fluid - filled container ; a control unit for enabling a user to increase or reduce an amount of fluid in the container ; and a stirrup - shaped device for immobilizing the talocalcaneonavicular joint and for controlling and / or stabilizing the ankle joint . the insole is a prefabricated insole selectable from a range of differently shaped insoles for the various forms of foot prophylaxis and the various shoe sizes . the insole can also be configured in combination with a athletic sock and can be configured as a partial insole . this enables users to adapt the prefabricated insoles suitable for their shoe size and form of foot prophylaxis to their own personal needs .