Generic Modeling of Contact and Fluid Pressures in Human Knee Joint for a Subpopulation

Subject-specific or patient-specific knee finite element modeling is time-consuming and technically challenging due to complex joint topology and multiple mechanical contacts involving several hard and soft tissues. It is even more challenging when the time variable is implemented to simulate fluid pressure and flow in the cartilaginous tissues. Various simplifications and modeling errors in finite element simulations based on a few knee joints have led to diverse or even conflicting results in the literature. Diverse approaches coupled with population variability may have resulted in subjective or subject-specific conclusions. Our research aims to understand the consequence of population diversity, including sex and ethnic differences in knee anatomy and tissue properties, through modeling a large population to find generic and subject-specific biomechanical behaviors. The objective of the present study was to develop a generic finite element knee modeling approach with statistical shape modeling. A fibril reinforced poromechanical model was used, which considered soft tissues as fluid-saturated materials. The virtual models were tested with subject-specific models to demonstrate the validity of the finite element solutions. The results from the virtual models were found reasonable as compared to those of subject-specific models based on individual knees. Joint mechanics for a large cohort may be more effectively determined with statistical results from principal modes and their variations, as compared to finite element modeling of every single knee.