The influence of the representation of collagen fibre organisation on the cartilage contact mechanics of the hip joint

Abstract

The aim of this study was to develop a finite element (FE) hip model with subject-specific geometry and biphasic cartilage properties. Different levels of detail in the representation of fibre reinforcement were considered to evaluate the feasibility to simplify the complex depth-dependent fibre pattern in the native hip joint. A FE model of a cadaveric hip with subject-specific geometry was constructed through micro-computed-tomography (µCT) imaging. The cartilage was assumed to be biphasic and fibre-reinforced with different levels of detail in the fibre representation. Simulations were performed for heel-strike, mid-stance and toe-off during walking and one-leg-stance over 1500 s. It was found that the required level of detail in fibre representation depends on the parameter of interest. The contact stress of the native hip joint could be realistically predicted by simplifying the fibre representation to being orthogonally reinforced across the whole thickness. To predict the fluid pressure, depth-dependent fibre organisation is needed but specific split-line pattern on the surface of cartilage is not necessary. Both depth-dependent and specific surface fibre orientations are required to simulate the strains.

Hip chondrolabral mechanics during activities of daily living: Role of the labrum and interstitial fluid pressurization

“…Additionally, this is the first study to use a physiological transchondral fibril reinforcement defined using a gradient between zones to scale the contributions from the ellipsoidal fiber distribution model throughout the layer. This is in contrast to other methods, for instance, which used distinct layers with orthogonal fibril reinforcement (Li et al, 2016). The final mesh included 7 layers of hexahedral elements through the thickness with biasing towards the articular and osteochondral surfaces, which is more refined than previous studies.…”

Development and validation of a finite-element musculoskeletal model incorporating a deformable contact model of the hip joint during gait

“…The labrum was excluded because it provides little assistance in load bearing of the hip (Henak et al, 2011). The timedependent biphasic/viscoelastic properties of the cartilage was not considered, because it is highly timeconsuming to achieve numerical convergence in biphasic simulations and the time-dependent response of the hip cartilage is minimal during short term loading (Li et al, 2013, Li et al, 2016, Todd et al, 2018.…”

“…A natural hip model from a 55 year-old, 109 kg, 180 cm male was incorporated into the FE musculoskeletal model, considering the cartilage with subject-specific geometry (Li et al, 2016). The modelling of the hip joint is based on a previously validated procedure (Li et al, 2014).…”

“…For example, finite-element (FE) models have been widely used to study stresses and strains within the hip (Henak et al, 2014, Li et al, 2016). These regional hip models require contact forces of the joint as inputs.…”

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

“…Using these formulations, previous researchers simulated collagen remodelling based on mechanical parameters such as the principal strain directions to predict fiber alignment in the depth-wise direction (Cortez et al, n.d.; Wilson et al, 2006). Other researchers introduced pre-assumed cartilage split line orientations in fiber reinforced finite element models to study their influence on predicted cartilage strain patterns (Li et al, 2016; Mononen et al, 2012; Shim et al, 2016). However, while these continuum based FE models accurately capture the net mechanical response of cartilage (Julkunen et al, 2013) and provide insight into the mechanical effects of collagen fiber orientation, they do not provide a biomechanical explanation for the characteristic collagen fiber orientations that are observed in the cartilage surface.…”