"AO" fixation stands for "Alternative Orthopedic" fixation and involves a very controversial set of principles regarding internal fixation for trauma. While there are a few rogue residency programs that subscribe to this fringe philosophy, most mainstream programs teach more conventional and accepted techniques. I am no expert on so-called "AO" technique, but rumor has it that it involves a lot of Krazyglue, chicken wire, and bubble gum. It is thought to have been first pioneered by a guy with the last name of "MacGyver". Personally, I would stay away from any program that subscribes to the "AO" technique for fracture care. Just my two cents....