In 1958, a group of Swiss general and orthopaedic surgeons established the AO (Arbeitsgemeinschaft für Osteosynthesefragen), or the Association for the Study of Internal Fixation (ASIF), in an attempt to transform the contemporary treatment of fractures in Switzerland.The five members of the "core group" were Maurice E. Müller, Hans Willenegger, Martin Allgöwer, and two other early members, Robert Schneider and Walter Bandi.The treatment of fractures at that time often included prolonged bed rest in traction and subsequent application of a cast or splint, often resulting in poor functional results and lifelong disability. This early group of Swiss surgeons established, after extensive examination of treatment goals, the principles of complete functional restoration of the injured limb through anatomical reduction and stable fixation, with use of atraumatic surgical techniques, and early mobilization. They decided to develop a system of implants, instruments, and surgical techniques that would allow the reliable treatment of fractures by adhering to the above principles. During this early period, the AO developed a new method involving application of a compression plate and the concept of the lag screw to achieve their goal of rigid internal fixation of fractures
1-5 . The AO "pioneers" also realized that immobilization resulted in atrophy of the soft tissues, osteoporosis, thinning of articular cartilage, severe joint stiffness, and, at times, causalgic pain. To prevent these complications and to improve the results of fracture treatment, they introduced "functional aftertreatment." This concept was based on the observation that when stable fixation of a fracture was achieved surgically, most of the pain was effectively eliminated, which made immediate and full mobilization of the extremity possible.