Computerassistierter Ersatz des vorderen Kreuzbandes - Entwicklung eines durchleuchtungsbildgeführten, computerassistierten Verfahrens zur arthroskopischen Kreuzbandplastik und Vergleich zu konventionellen Instrumenten

This thesis aims at improving positioning accuracy that is crucial for the longevity of anterior cruciate ligament surgery. The other aspects like transplant choice, means of fixation, pretensioning and activity level dependent differential indication are beyond the scope of this work. Conventional instruments for precise positioning are available. These are mechanical aiming guides that support both tibial and femoral bone tunnel drilling. Starting from the radiographic quadrant method by Bernard and Hertel to assess positioning accuracy a system for C-arm based, computer-assisted arthroscopic surgery was preclinically developed. The system integrates arthroscopically identified landmarks like the desired insertion in the tibial plateau with landmarks acquired by image guidance like the desired origin at the lateral femoral condyle. It consequently measures isometry throughout the range of motion and provides navigation of the drill bushing for computer assisted bony tunnel drilling. The accuracy of the system is better than 2mm for the two crucial steps of transfer of radiographic plans to the anatomy and drilling of a trajectory defined by landmarks in the situs, which satisfies clinical requirements. Use of the system parallel to arthroscopy is feasible and provides the surgeon with information on radiologic target criteria with acquisition of only two images in the beginning of the procedure. Without the proposed system this would require repeated irradiation. Furthermore, it provides isometry measurement even prior to the first drilling of a guidewire, which is impossible with mechanical guides that do not allow for a change of plans that easy.