[Knee arthroplasty. Mobile- and fixed-bearing design]

After the introduction of mobile-bearing knee arthroplasty in the late 1970s, he benefits were discussed in comparison to the well-established modular fixed-bearing systems. The hypothetical advantages of mobile-bearing designs are the ability of axial rotation and a greater articular conformity, which reduces significantly fatigue failure of the polyethylene. Biomechanical analyses showed for each system characteristic features, which are not concordant with the aim of restoring normal knee kinematics. In both groups the long-term clinical results were excellent with 10-year survival rates of 95-98%. Ligamentous stability and a perfect operative technique are key factors in mobile-bearing knee arthroplasty. Prospective randomized clinical trials are necessary to find answers concerning backside and volumetric polyethylene wear and the detrimental effects of wear particle size. Before this is accomplished, the indication for a mobile-bearing knee arthroplasty, especially in young patients, should be carefully considered in each case.