[Useability of an image based nagivation system in reconstruction of leg alignment in total knee arthroplasty - results of a propsective study]. / Einfluss eines bildgestützten Navigationssystems auf die Implantationsgenauigkeit in der Knieendoprothetik--Ergebnisse einer prospektiven Studie.

Accurate leg alignment is one important factor for long term survival in total knee arthroplasty (TKA). The aim of this study was to determine the accuracy of a CT-based navigation system in restoration of the leg axis. 80 TKA (P.F.C.-Sigma--DePuy) were implanted either using a CT-based navigation-system or the conventional technique. There were no significant differences between the groups according to the preoperative leg deformity. Accuracy of implantation was determined on postoperative long-leg coronal and lateral x-rays. A postoperative leg axis between 3 degrees varus and 3 degrees valgus was obtained in 35/40 patients (88%) in the computer assisted and 28/40 patients (70%) in the conventional operated group. A higher precision in the sagittal plane was seen for the tibial (computer assisted: 3.9 +/- 2.2 vs. conventional TKA 1.3 +/- 5.8) and the femoral component (computer assisted: 3.5 +/- 2.3 vs. conventional TKA 6.9 +/- 3.6). The use of the CT-based VectorVision-System allows a significant improvement in the accuracy of implantation in TKA. The CT-based module has the advantage of a precise preoperative planning and a useful documentation and control tool for each important step. On the other hand there are additional costs and time consuming logistics.