Simulation of surface strain in tibiofemoral cartilage during walking for the prediction of collagen fibre orientation

Abstract

The collagen fibers in the superficial layer of tibiofemoral articular cartilage exhibit distinct patterns in orientation revealed by split lines. In this study, we introduce a simulation framework to predict cartilage surface loading during walking to investigate if split line orientations correspond with principal strain directions in the cartilage surface. The two-step framework uses a multibody musculoskeletal model to predict tibiofemoral kinematics which are then imposed on a deformable surface model to predict surface strains. The deformable surface model uses absolute nodal coordinate formulation (ANCF) shell elements to represent the articular surface and a system of spring-dampers and internal pressure to represent the underlying cartilage. Simulations were performed to predict surface strains due to osmotic pressure, loading induced by walking, and the combination of both loading due to pressure and walking. Time-averaged magnitude-weighted first principal strain directions agreed well with split line maps from the literature for both the osmotic pressure and combined cases. This result suggests there is indeed a connection between collagen fiber orientation and mechanical loading, and indicates the importance of accounting for the pre-strain in the cartilage surface due to osmotic pressure.

Stress-adaptive design of 2D contact interfaces with uniform pressure: A bio-inspired approach

“…Farther from the surface, they are oriented perpendicularly to the surface [43]. In fact, it has been suggested that such preferential orientation might be related to the direction of principal strains [44]. Thus, growth orientation not only influences the shape but clearly also the mechanical properties of the cartilage, particularly, its anisotropic nature.…”