From traction to osteosynthesis

October 15, 2026

A group of Swiss surgeons, a laboratory in Davos, and a bold vision for better patient outcomes transformed osteosynthesis from a controversial technique into the global standard of fracture care.
 

Today, the principles of osteosynthesis are taught in operating rooms and training centers around the world. Surgeons routinely stabilize fractures with plates, screws, and nails, enabling patients to mobilize sooner and recover more effectively. Yet less than a century ago, prolonged traction, plaster casts, and weeks of immobilization were the norm.

The story of how modern fracture fixation emerged is inseparable from the history of the AO. Founded in Switzerland in 1958, the Arbeitsgemeinschaft für Osteosynthesefragen (Association for the Study of Internal Fixation) challenged established dogma and developed a scientific approach to fracture treatment that continues to shape musculoskeletal care today.

Fracture treatment before the AO

In the late 1940s, treatment options for fractures were limited. Patients with broken legs often spent weeks in traction before receiving a plaster cast. Recovery was long and unpredictable, and many were left with permanent disability.

The consequences were significant: Around 40 percent of patients with tibial fractures and 70 percent of those with femoral fractures were receiving lifetime invalidity pensions from Swiss Accident Insurance (SUVA) following their injuries. Joint stiffness, muscle atrophy, chronic swelling, and loss of function were common outcomes.

While some pioneers had begun experimenting with surgical fixation, it remained controversial. Concerns about infection, implant failure, and poor results limited its acceptance within the broader surgical community.

One surgeon who saw the potential of osteosynthesis was the Belgian physician Robert Danis. Through decades of clinical work, Danis developed techniques based on rigid fixation and compression, publishing his ideas in Théorie et Pratique de l'Ostéosynthèse in 1949. His work would profoundly influence a young Swiss surgeon named Maurice Müller.

The making of a pioneer

After completing his medical degree in 1946, Müller sought opportunities to learn from leading surgeons across Europe. During his early career, he encountered patients whose fractures had been treated using innovative surgical techniques, including intramedullary nailing pioneered by Gerhard Küntscher. These experiences convinced him that fracture care could be dramatically improved.

A pivotal moment came in March 1950. At the recommendation of Dutch orthopedic surgeon Cornelis Pieter van Nes, Müller travelled to Brussels to meet Robert Danis. The visit lasted only one day, but its impact would last a lifetime. Müller later described Danis's work as one of the most important influences on his career. Returning to Switzerland, he began applying and refining osteosynthesis techniques while building a network of like-minded surgeons. 

A meeting in Biel that changed everything

On November 6, 1958, thirteen Swiss surgeons gathered at the Hotel Elite in Biel. Their goal was ambitious: transform fracture treatment through science, collaboration, and standardization.

Among the group's leaders were Maurice Müller, Martin Allgöwer, Hans Willenegger, Robert Schneider, and Walter Bandi. Together, they established the Arbeitsgemeinschaft für Osteosynthesefragen (AO).

Unlike many medical societies of the era, the AO was not founded simply to exchange ideas. Its members set out to create a complete system for fracture treatment based on evidence rather than tradition. They understood that successful innovation would require more than new implants. It would require research, documentation, education, and quality control.

Davos becomes the AO's laboratory

Even before the AO was formally established, Martin Allgöwer had identified a suitable location for experimental research: a former pathology institute at Villa Fontana in Davos.

In 1959, the founders invested their own money to renovate and equip the building, creating the AO's first research facility, the Laboratory for Experimental Surgery. What began as a modest laboratory would grow into today's AO Research Institute Davos (ARI), one of the world's leading centers for musculoskeletal research.

The laboratory played a critical role in turning surgical ideas into scientifically validated techniques. Researchers investigated fracture healing, biomechanics, implant performance, and the biological effects of fixation. This commitment to evidence distinguished the AO from many contemporary surgical movements.

Engineering a new approach to fracture fixation

The AO founders recognized that reliable surgery required reliable tools.

Working closely with Swiss industrial partners, they developed standardized implants and instruments designed specifically for fracture fixation. Early innovations included compression plates, lag screws, and the cortical bone screw, all designed to achieve stable fixation while supporting biological healing.

Just as important as the implants themselves was the philosophy behind them. AO surgeons observed that stable fixation reduced pain and enabled patients to move sooner. This challenged the prevailing belief that prolonged immobilization was necessary for healing.

The resulting concept of "functional after-treatment" became one of the most influential contributions in trauma surgery. Early mobilization not only improved patient comfort but also reduced complications associated with lengthy immobilization.  

Teaching the world

Innovation alone was not enough. To achieve widespread adoption, surgeons needed training.

In 1960, the AO organized its first instructional course in Davos. Surgeons learned fracture fixation techniques directly from the founders in a highly structured educational environment. Demand grew rapidly. By the second Davos course in 1961, participation had nearly doubled and international attendees were already arriving from abroad.

These courses established a model of surgical education that remains central to AO activities today: combining scientific evidence, practical training, peer learning, and rigorous standards.

What began in Davos soon spread across Europe, North America, and beyond, helping to create a truly global network of surgeons dedicated to improving patient care.

A lasting legacy

The transformation initiated by the AO's founders extended far beyond implants and operating techniques. By documenting outcomes, conducting research, developing instrumentation, and educating generations of surgeons, the organization created a framework for continuous improvement in musculoskeletal care.

Nearly seven decades after that meeting in Biel, the influence of Maurice Müller and his colleagues remains visible in operating rooms around the world. Their conviction that fracture care could be improved through science, collaboration, and education transformed osteosynthesis from a niche technique into one of the most significant advances in modern surgery.