In Arizona, you only have two years from the date of the accident to bring a lawsuit against those who are responsible for causing it: “Except as provided in section 12-551 there shall be commenced and prosecuted within two years after the cause of action accrues, and not afterward, the following actions: 1. For injuries done to the person of another including causes of action for medical malpractice as defined in section 12-561.”
After this period expires, an individual cannot bring an action regardless of how serious their injuries may be.