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1.1 This practice establishes requirements and considerations for the numerical simulation of metallic orthopaedic total knee tibial components using Finite Element Analysis (FEA) techniques for the estimation of stresses and strains. This practice is only applicable to stresses below the yield strength, as provided in the material certification.

1.2 Purpose—This practice establishes requirements and considerations for the development of finite element models to be used in the evaluation of metallic orthopaedic total knee tibial component designs for the purpose of prediction of the static implant stresses and strains. This procedure can be used for worst-case assessment within a series of different implant sizes of the same implant design to reduce the physical test burden. Recommended procedures for performing model checks and verification are provided as an aid to determine if the analysis follows recommended guidelines. Finally, the recommended content of an engineering report covering the mechanical simulation is presented.

1.3 Limits—This practice is limited in discussion to the static structural analysis of metallic orthopaedic total knee tibial components (which excludes the prediction of fatigue strength).

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

3.1 This practice is applicable to the calculation of stresses seen on a knee tibial component when loaded in a manner described in this practice. This practice can be used to identify the worst-case size for a particular implant. When stresses calculated using this FEA method were compared to the stresses measured at two locations on the tibial tray using physical strain gauging techniques performed at one laboratory, the difference observed was -6.8 % at one location (with the strain gauges reporting the higher stress) and 3.1 % at the other location (with the FEA method reporting a higher stress). This difference should be considered when determining the worst-case size(s) of the same implant design.

3.2 The loading of tibial tray designs in vivo will, in general, differ from the loading defined in this practice. However, this practice is designed to allow for comparisons between the fatigue performance of different metallic tibial component designs, when tested under similar conditions.