Soft EHL Modeling of Total Knee Arthroplasties

Marian M, Rothammer B, Tremmel S (2019)

Publication Language: English

Publication Type: Conference contribution, Conference Contribution

Publication year: 2019

Event location: Sendai JP

Abstract

Total knee arthroplasty (TKA) is an effective surgical treatment against gonarthrosis and rheumatoid arthritis to retrieve the function of the knee. However, wear as well as associated osteolysis and aseptic loosening are the most common reasons for premature implant failure. In general, TKA consists of a metallic femoral component rubbing against the bearing surface of the (tibial) ultrahigh molecular weight polyethylene (PE‑UHMW) inlay. Several studies aim on the reduction of polymeric wear debris and thus abrasive wear by geometrical optimization or surface modification, such as micro-texturing and applying tribological coatings. For an adequate TKA design, fundamental knowledge about present lubrication conditions and stresses is vital.

Therefore, a fully coupled transient 3D model of the soft elastohydrodynamically lubricated (soft EHL) contact in total knee arthroplasties was developed. For the hydrodynamics, a modified generalized Reynolds equation was applied. Based upon the finite element method (FEM), the elastic deformation was computed for an equivalent body by applying the linear elasticity equation. Moreover, for example time-dependent squeeze effects, mixed lubrication, microhydrodynamics, mass-conserving cavitation as well as thermal and non-Newtonian effects were to be considered.

Numerical modeling along with exemplary results are presented and discussed within the scope of this contribution. Special emphasis is put on rheological properties of synovia from different individuals as well as synthetic synovial testing fluid. It is shown that variations in those properties, in particular viscosity, have a decisive influence on lubrication conditions and thus also on potential wear. Based on this knowledge, patient-specific geometric optimizations or surface modifications can be designed.

Authors with CRIS profile

Max Marian Chair of Engineering Design Benedict Rothammer Chair of Engineering Design Stephan Tremmel Chair of Engineering Design

How to cite

APA:

Marian, M., Rothammer, B., & Tremmel, S. (2019). Soft EHL Modeling of Total Knee Arthroplasties. In Proceedings of the International Tribology Conference Sendai 2019. Sendai, JP.

MLA:

Marian, Max, Benedict Rothammer, and Stephan Tremmel. "Soft EHL Modeling of Total Knee Arthroplasties." Proceedings of the International Tribology Conference Sendai 2019, Sendai 2019.

BibTeX: Download