AO Innovation Translation Center - Technology Transfer | October 2021

OSapp fosters understanding of biomechanical concepts behind fracture fixation

Peter Varga, Simon Lambert

Officially launched at the AO Davos Courses 2020, a new, interactive, and constantly expanding virtual osteosynthesis software tool and interactive online learning platform—OSapp—fosters understanding of the biomechanical concepts underlying the principles of fracture fixation. Initially supported by the AO Research Institute Davos (ARI), OSapp has been further developed with support from the AO Innovation Translation Center (AO ITC) strategy fund.

Since its public debut at the AO’s flagship annual event in December 2020, the OSapp interactive osteosynthesis learning platform has achieved more than 1,700 registered users and 4,600 visitors from 121 countries. The platform’s onboard survey tool indicates that 90 percent of respondents found OSapp useful or useful, and more than 90 percent will highly recommend it to their colleagues.

The problem

The OSapp project stems from a discussion between ARI Biomechanics and Modeling Focus Area Leader Peter Varga, PhD, and AO Technical Commission Upper Extremity Global Expert Group Committee member and longtime AO Trauma faculty Simon Lambert, MD. That discussion centered on a perceived gap in AO Davos Courses 2018 participants’ understanding of the biomechanical concepts underlying the principles of fracture fixation.

The solution

Varga and Lambert suggested a solution: a tool that could act as an interactive reminder of those biomechanical concepts and illustrate the principles of fracture fixation. The resulting OSapp tool is a virtual environment allowing users to experiment with various scenarios and immediately understand the outcomes of their decisions which in turn powers learning. Playing a valuable advisory role in aiding OSapp’s development was AO's founding father and senior scientific advisor Prof Stephan Perren, until just a few days before his death in November 2019.

An offline version of OSapp was demonstrated at the AO Davos Courses 2019 and was met with positive feedback. The clinical relevance of OSapp’s content is ensured by the supervision of renowned experts, Reto Babst, Florian Gebhard, Martin Jaeger, Michael Schuetz, and Simon Lambert, who comprise the OSapp Medical Advisory Board.

The 30-month project that began in July 2020 is today an engaging online learning platform on which anyone can register and use OSapp. The platform's content is continuously being expanded and includes both a free configurator and a virtual clinical case discussion. Users can also access guided lessons through which they can view a selection of biomechanical principles via 3D computer simulations. When users successfully demonstrate knowledge of the principles underlying fixation, they can appreciate the positive impact it has on fracture healing.

The OSapp development team has established a collaboration with the ICUC medical research group to link ICUC cases to OSapp. Additionally, a series of new OSapp content extensions is planned for later this year based on input from users, the advisory board, and AO medical research fellows.

The latest OSapp content will be showcased at the AO Davos Courses 2021, and discussions are underway to gauge how the platform can best be used to support AO educational activities, such as the AO Trauma Competency-based Training and Assessment Program (CTAP) and AO Trauma Residents education program.


Fig 1 View on a digital case discussion


Lambert S, Mischler D, Windolf M, et al. From creative thinking to scientific principles in clinical practice. Injury. 2021Jan;52(1):32–36.

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