Original Article Internal Fixation of Femoral Neck Fractures with Computer Assisted Surgery A Report on First Cases Niels W.L. Schep, Egbert J.M. Verleisdonk, Ivo A.M.J. Broeders, Floor M. Kappelhoff, Chris van der Werken 1 268 European Journal of Trauma 2003 · No. 5 © Urban & Vogel European Journal of Trauma Abstract Background: In standard practice, osteosynthesis of femoral fractures is guided interactively by 2-D fluo- roscopy providing anteroposterior or axial projections. This approach leads to repetitive position changes of the C-arm with concomitant radiation exposure and may result in suboptimal positioning of implants. Fluo- roscopy-based navigation may offer a solution for these problems. The goal of this study was to evaluate the feasibility of fluoroscopy-based navigation in the treatment of intracapsular femoral neck fractures with a dynamic hip screw (DHS). Patients and Methods: Seven patients were treated with a 135° DHS. Fluoroscopy-based navigation tech- nique (Medivision, Oberdorf, Switzerland) was used for positioning the correct drill channel for the DHS. There- fore, the virtual position of an 8-mm noncannulated DHS reamer was superimposed simultaneously on the anteroposterior and axial images. Results: One procedure failed because the position of the virtual drill did not match the true situation. In this case, it was most likely that the dynamic reference base was moved relative to the proximal femur during the operation. This operation was continued under fluoro- scopic guidance. In one patient, the DHS was located in the cortex of the femoral head. In another patient the DHS was positioned not exactly in the center of the femoral neck, but slightly posterior. Mean system set- up time was 10 minutes Conclusion: Fluoroscopy-based navigation is a feasible technique for the treatment of femoral neck fractures with a DHS. The initial results are encouraging. More intuitive techniques are currently being developed to enhance the application of navigation in routine trau- ma care. Key Words Computer assisted surgery · Fluoroscopy · Femoral neck fractures · Dynamic hipscrew Eur J Trauma 2003;29:268–72 DOI 10.1007/s00068-003-1228-1 Introduction The dynamic hip screw (DHS, AO-Synthes ® ) is a popu- lar implant for the stabilization of femoral neck frac- tures. An essential part of the operation is the insertion of a guide wire over the calcar into the femoral head under fluoroscopic guidance. The drawback of this technique is the intraoperative visualization, because positional information of the K- wire is limited to single, two-dimensional (2-D) fluoro- scopic projections. This leads to repetitive position changes of the C-arm because both anteroposterior and axial images are required and makes the procedure prone to imperfect positioning of the implant. More- over, interactive fluoroscopic guidance results in a sub- stantial radiation exposure to both patients and the sur- gical team [1, 2]. Fluoroscopy-based navigation may offer a solution to these problems. With this technique, the virtual posi- tion and direction of a drillbit is simultaneously super- 1 Department of Surgery, University Medical Center Utrecht, The Netherlands. Received: June 12, 2003; revision accepted: December 30, 2003.