Numerical modeling of lubrication mechanisms in total knee replacements

Marian M, Rothammer B, Bartz M, Nečas D, Vrbka M, Wimmer MA, Wartzack S (2021)


Publication Language: English

Publication Type: Conference contribution, Conference Contribution

Publication year: 2021

Event location: Online

Abstract

For an adequate design of total knee replacements (TKR), knowledge about stresses and lubrication conditions is vital. Within this study, a numerical model based upon the Finite Element Method and fully coupling the fluid’s hydrodynamics (generalized Reynolds equation) with the elastic deformation of the contacting bodies is presented. Thereby, realistic transient kinematics and loading conditions of the gait cycle (ISO 14243) were considered. For the numerical results, good agreement with experimental studies by means of a knee simulator with optical fluorescent measurement technique was achieved. Moreover, it was found that the complexity of numerical modeling has a strong effect on simulation results and thus on the prediction quality, especially for the fluid film height. The consideration of transient squeeze effects, non-Newtonian fluid characteristics, realistic geometries, transient kinematics and loading conditions is vital. The medial compartment was more heavily stressed and experienced higher pressures and smaller minimum film heights compared to the lateral condyle. The swing phase was determined by geometry and kinematics while load and geometry played a dominant role in the stance phase, where the overall lubricant gap was smaller. Generally, the reversal points of motion with zero entrainment speed largely affected the fluid film formation. Furthermore, the individual rheological synovial fluid parameters have a decisive influence on the lubricant film formation. Due to the wide variation between different patients, this can also lead to diverse tribological behavior ranging from full separation of the rubbing surfaces over the whole gait cycle to strong solid asperity contact and associated wear mechanisms.

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APA:

Marian, M., Rothammer, B., Bartz, M., Nečas, D., Vrbka, M., Wimmer, M.A., & Wartzack, S. (2021). Numerical modeling of lubrication mechanisms in total knee replacements. In Proceedings of the 5th International Conference on BioTribology. Online.

MLA:

Marian, Max, et al. "Numerical modeling of lubrication mechanisms in total knee replacements." Proceedings of the 5th International Conference on BioTribology, Online 2021.

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