Navigationssysteme in der Hüftendoprothetik. Ein In-vitro-Vergleich bildfreier und bildbasierter Systeme mit der konventionellen Handimplantation der Hüftgelenkspfanne

The use of navigation systems for total hip replacement becomes increasingly popular although a significant better cup placement compared with manual technique has not shown for surgeons with different operating experience. Aim of this in-vitro study was to compare the hip cup placement when using different navigation systems compared with the traditional, non-navigated technique. Five different navigation systems were used: Navitrack™ (CT-less), Navitrack™ (CT-based), Orthopilot™ (CT-less), VectorVision™ (CT-based) and SurgeticsStation™ (CT-less). Three different surgeons carried out five cup implantations using all navigation systems and the manual approach on a surgery dummy with a pelvis specimen inside. Cup orientation (inclination and anteversion) and the cup position (achieved cup center) were determined with a coordinate measuring machine and compared to planned values. The deviation angles and vectors were plotted. In the manual group the variability of the cup orientation was higher in comparison to the navigated groups and hardly influenced by the surgeon. One surgeon achieved a significantly shorter operating time. He was more experienced than the others; however, his cup placement was not better compared with his colleagues with less surgical experience. Navigation was identified as a significant factor for smaller deviations from planned inclination and anteversion angles (p<0,001 for both). Cup position was not affected by surgeon in the manual group (p=0,966). Compared with manual technique, the cup misplacement vector was significantly smaller in the CT-Navitrack group (p<0,001) but higher in the Navitrack (CT-less) and VectorVision group (p<0,001). The use of computer navigation will help the surgeon to orientate the acetabular component more accurately but not necessarily with regard to cup positioning.