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Preliminary clinical experience using a newly developed minimal-invasive reference base in computer assisted foot surgery.

In recent years, many new tools and techniques have been developed in computer assisted orthopaedic surgery primarily with an industry led effort in software innovation and development. Only a few research and clinical projects have focused on intraoperative difficulties. A common operative challenge in computer assisted orthopaedic surgery is the positioning of the reference base. Rigid fixation of a dynamic reference base is essential in navigated surgery of the extremities. The aim of this study was to develop a minimal-invasive screw which could be placed effectively and efficiently with rotational stability during computer assisted orthopaedic surgery. The minimal-invasive screw was initially evaluated in an artificial bone experiment. After successful results with the artificial bone experiment, it underwent testing in seven human cadaver thighs with ISO-C3D navigated drilling. Finally the screw was transferred into a clinical application during five foot surgeries. In 10 ISO-C3D navigated drillings, the lesions were targeted 100% of the drillings. A screw dislocation was not observed. In comparison to conventional one or two pin fixation systems, the newly designed small screw did not have any observed side effects such as artifacts. In addition, the screw generated less heterodyning than a conventional fixation system. The small screw design is an advantage in theatre. We believe the minimally-invasive screw allows the surgeon to use a tool that helps avoid common pitfalls from conventional fixation systems, and it may improve efficiency.