In knee arthroplasty a ceramic component has several advantages: first, there is no ion release implying a risk for potential allergies. Second, the hardness of the material leads to a scratch resistance which ultimately reduces PE wear over time. In the past, ceramic components in knee applications were limited in the variety of design possibilities due to necessary thickness of the component resulting from the associated fracture risk of ceramics. By the development of an alumina matrix composite material with increased mechanical properties it is possible to develop ceramic knee components which have nearly the same design as a metal component and use the same implantation technique as well as the same instruments. This offers the surgeon the opportunity to choose intraoperatively between metal or ceramic knee components. Extensive in-vitro testing shows that ceramic knee components achieve superior mechanical test results. The reliability of the components is proven by two different burst tests and a fatigue test for both a femoral and a tibial ceramic knee component. The mechanical proof-test was developed by subsequent steps of numerical load/stress analysis and design of an adequate mechanical test equipment. The procedure was organized as follows: Oncologic: Analysis of relevant maximum in-vivo loading conditions Analysis of the “boundary conditions” Finite Element analysis: Identifying regions of highest stress concentration Design analysis and accommodation if necessary Development of an adequate mechanical test equipment which produces stresses comparable to the in-vivo conditions Performing mechanical tests with ceramic femoral components Validation of the test concept: comparison of test results and stress analysis Assign “safety margin”, Establish “proof test”Introduction
Material and method
