Successful outcome in TKA is influenced by the accuracy of the bone cuts, the reconstruction of the anatomical axes,implant design geometry and the active and passive soft tissue structures surrounding the articulation. They determine stability,range of motion and interface stress of the replaced knee joint and of course the clinical result. Since August 2000 we use regukarly the GALILEO-CAS and GALILEO-NAV System in TKA with the TC-PLUS(TM) Solution Knee.

Method: For preoperative planning there is no need of any CT-Scan, neither of the knee,nor of the hip. We need a single-leg-stand-up a-p and m-l X-ray to determine the the mechanical axis and Alpha-angle. Starting the navigated operation 20 measurements are taken to determine the rotational center of the hip. The several anatomical points are measured to construct a virtual model of the operated knee. After measurement the GALILEO-System proposes size and position of the prosthesis. After confirmation of these parameters the motor driven cutting blocks are automatically positioned to produce reliable bone cuttings. Step by step the femoral and tibial cuts can be performed under navigated computer assistance. Nevertheless all the time, the surgeon has the opportunity to manually overwrite the recommended position. At the end of the implantation we can test the ligamentous stability of the joint using Computer Assisted Surgery (CAS)system.

Evaluation: For evaluation of the clinical and biomechanical outcome of CAS, we started a prospective randomized study to compare it with the conventional operated TKAs. From Sept.2000 to June 2001 we performed 200 TKAs with the TC-PLUS(TM)Solution Knee. 100 of them were operated on conventionally; for the remainer we used CAS. The outcome was assessed according to HSS-Score and Insall-Score, pre op,post op 12 days,12 weeks and 6 months.

First results: First trends show a higher reliability of bone cuts in the CAS-Group, better restitution of anatomical axes, an improvement of the ROM 6 months post op and a higher clinical score.

Further evaluation of the mid and long term results are necessary to evaluate the effectiveness of Computer Assisted Surgery in Total Knee replacement.