Federal health regulators will begin tracking millions of medical devices, from pacemakers to hip replacements, using a new electronic system designed to protect patients by catching problematic implants earlier. The Food and Drug Administration published new rules Friday that require most medical devices sold in the U.S. to carry a unique code, identifying its make, manufacture date and lot number. The codes will be stored in a publicly accessible database to help regulators, doctors and companies monitor safety issues with devices. The tracking system has been promoted by doctors and public safety advocates for years. Other industries, from food processors...