Cities of the first and second class of this Commonwealth be, and are hereby, authorized and empowered to pay all persons in their employ during absence from their employment, caused by injuries, sickness, or disablement of any kind whatsoever, sustained in the performance of their duties: Provided, That such compensation made by the city shall only be equal to the amount of wages or salary said person would have received during the period of absence from his or her employment, and never for a period of time to exceed one year.
53 P.S. § 631