Selecting a cartilage constitutive model for finite element analysis of cartilage impact injuries

Articular cartilage is a flexible tissue that helps distribute loads to the underlying bone. To understand how cartilage diseases progress, it's important to study how its mechanical behavior affects its biological activity. Computer models can be made to calculate cartilage mechanical behavior, although how the structure of the cartilage is represented in the model can affect the model’s accuracy. This study investigated how adding more detailed fluid and solid elements to the cartilage description affects the accuracy of the computer model during two different injuries that involve an impact to the cartilage.

The complexity of the fluid and solid descriptors of the cartilage was systematically increased and decreased to examine how these changes affected the computer model's calculation of cartilage mechanics. Including a more detailed description of fluid behavior had minimal effects on the values calculated by the computer model. However, including more details about the solid components of cartilage did significantly change calculations of cartilage mechanics. An experiment comparing computer model results to results measured on real cartilage showed that adding more detailed solid components made the computer model’s results match real-world measurements more closely. Therefore, including more detailed solid components of cartilage in the computer model is best when comparing to the biological activity of cartilage.