A police officer whose duty is suspended because of disability may be summoned to appear before the board, and to submit to an examination to determine fitness for duty. The officer shall abide by the board’s decision. If a police officer retired for disability, except one who voluntarily retires after 20 years’ service, is found upon medical examination to have recovered from disability, the board shall certify to the chief of police that the member is no longer disabled and is able to resume the duties of his or her position. In case of emergency, a disabled police officer may be assigned to and shall perform such duty without right to compensation as the chief of police or chief officer of the municipality may direct. This Section does not apply to a police officer who has attained the age of 60.