Diese prospektive radiologisch-klinische Studie vergleicht die Eignung dreier anatomischer Strukturen (Sehne des M. tibialis ant., Tibiavorderkante und Intermetatarsal-raum I) als intraoperative Landmarke bei der Implantation der Tibia-Komponente eines bikondylären Oberflächenersatzes mit einer mobilen Gleitlage. Eine möglichst genaue mechanische Achsausrichtung trägt laut Fachliteratur nicht nur zur langen Standzeit des Implantats bei, sondern führt auch zu einer früheren Rehabilitation und somit zu besserer klinischer Funktion des operierten Knies. Im Rahmen der Studie wurden insgesamt 29 Patienten rekrutiert, die zur Implantation einer LCS® Prothese (DePuy, Warsawa, USA) anstanden. Das Studiendesign beinhaltete eine präoperative Body Mass Index und Knee Score Bestimmung, eine Ganzbeinstandaufnahme und eine 3D-MRT-Bildanalyse. Die präoperative Achseinteilung ergab einen Varuswinkel (Tibiofemoral-Winkel, This prospective radiological-clinical study compares the suitability of three anatomical structures as intraoperative landmarks for the implantation of the tibial component in total knee replacement using bicondylar knee prosthesis with a mobile bearing system: Tendon of the tibialis anterior muscle, anterior edge of the tibia, first intermetatarsal space. According to previous research, a high level of precision in the reconstruction of mechanical alignment will not only contribute to a long life span of the implant, but also enable a quicker rehabilitation and thus a better clinical function of the prosthesis. In this research project, 29 patients awaiting treatment by total knee arthroplasty using the LCS Mobile-Bearing Knee System®, were recruited. In the course of the study, the following data was collected: a preoperative body mass index, clinical knee score, X-Ray a.p. lateral view single leg with patient standing and 3D-MRI analysis of the lower extremity. The recruited patients were then divided into three subgroups for statistical analysis according to their preoperative anatomical alignment: 16 patients with varus knees, 9 patients with physiological knees, 4 patients with valgus knees. In the 3D-MRI analysis, the positions of the three anatomical structures named above were compared to a virtually reconstructed mechanical axis. The analysis demonstrates that the position of the tendon of the tibialis anterior muscle reflects most closely the ideal implantation axis (Distance to mechanical axis: -1,66 +/-5,73mm), followed by the anterior edge of the tibia (-1,87 +/-2,58mm; p=0,859) and the first intermetatarsal space (3,01 +/-8,48mm; p= 0,006). The study concludes that the tendon of tibialis anterior muscle should be considered the best suitable structure of implantation of the tibial component. This is because it is characterized by the shortest mean distance from the mechanical axis, the least spread in the statistical data and high intra-observer reliability. However, the subgroup of patients with distinct varus deformity appears to be an exception. The differentiated analysis that takes the preoperative anatomical alignment into account reveals that the anterior edge of the tibia may be better suited as intraoperative landmark. This structure offers a low spread for this patient group, although its intra-observer reliability is lower than that of the tendon of the tibialis anterior muscle.