title: Calculation of the elastic properties of prosthetic knee components with an iterative finite element-based modal analysis: quantitative comparison of different measuring techniques.
abstract: With the aging but still active population, research on total joint replacements relies increasingly on numerical methods, such as finite element analysis, to improve wear resistance of components. However, the validity of finite element models largely depends on the accuracy of their material behavior and geometrical representation. In particular, material properties are often based on manufacturer data or literature reports, but can alternatively be estimated by matching experimental measurements and structural predictions through modal analyses and identification of eigenfrequencies. The aim of the present study was to compare the accuracy of common setups used for estimating the eigenfrequencies of typical components often used in prosthetized joints. Eigenfrequencies of cobalt-chrome and ultra-high-molecular weight polyethylene components were therefore measured with four different setups, and used in modal analyses of corresponding finite element models for an iterative adjustment of their material properties. Results show that for the low-damped cobalt chromium endoprosthesis components, all common measuring setups provided accurate measurements. In the case of high-damped structures, measurements were only possible with setups including a continuously excitation system such as electrodynamic shakers. This study demonstrates that the iterative back-calculation of eigenfrequencies can be a reliable method to estimate the elastic properties for finite element models.
authors.affiliation: Department of Orthopaedic Surgery, University Hospital of Munich LMU, Campus Grosshadern, 81377 Munich, Germany. Matthias.woiczinski@med.uni-muenchen.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Woiczinski
authors.forename: Christopher
authors.initials: C
authors.lastname: Tollrian
authors.forename: Christian
authors.initials: C
authors.lastname: Schröder
authors.forename: Arnd
authors.initials: A
authors.lastname: Steinbrück
authors.forename: Peter E
authors.initials: PE
authors.lastname: Müller
authors.forename: Volkmar
authors.initials: V
authors.lastname: Jansson
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D055119:Elastic Modulus; D019544:Equipment Failure Analysis / Q000295:instrumentation* / Q000379:methods; D020342:Finite Element Analysis; D007720:Knee Prosthesis; D008962:Models, Theoretical; D011474:Prosthesis Design / Q000295:instrumentation / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity