Navigation and robotics-current status and future implications

Abstract

Both navigation systems and robotics enable greater precision in the implantation of an artificial knee joint. However, they do not improve clinical outcomes. We hypothesized that although implantation of atotal knee arthroplasty results in reconstruction of the alignment in the coronal plane, the variable rotational tibial and variable translational femoral and tibial component positioning lead to achange in the remaining alignment parameters of the lower extremity. However, these parameters could be determined using anavigation system or robot and could represent future implications for these systems. The kinematics and the position between femur and tibia before and after implantation of atotal knee arthroplasty were determined using anavigation system in nine healthy knee joints of Thiel-fixed whole-body cadavers. After arthroplasty, there was no change in the natural coronal alignment. In extension and the early degrees of flexion, the rotational position of the femur relative to the tibia was altered. This also led to achange in the positioning of the medial and lateral epicondyle in relation to the tibia; while both epicondyles were positioned more laterally in relation to the tibia after arthroplasty, the lateral epicondyle was significantly more lateral in relation to the tibia up to 20° of flexion. Following arthroplasty of aknee joint using the established technique, agood reconstruction of the coronal alignment was achieved with simultaneous changes in the alignment in both the rotational and translational directions between the femur and tibia. Using navigation as well as robotics, we would be able to quantify all alignment parameters and could achieve an alignment of the components or areconstruction of the overall alignment in all six degrees of freedom. We might also be able to achieve aclinical advantage or increase the service life even further.