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

Abstract

Osteoarthritis of the hip can result from mechanical factors, which can be studied using finite element (FE) analysis. FE studies of the hip often assume there is no significant loss of fluid pressurization in the articular cartilage during simulated activities and approximate the material as incompressible and elastic. This study examined the conditions under which interstitial fluid load support remains sustained during physiological motions, as well as the role of the labrum in maintaining fluid load support and the effect of its presence on the solid phase of the surrounding cartilage. We found that dynamic motions of gait and squatting maintained consistent fluid load support between cycles, while static single-leg stance experienced slight fluid depressurization with significant reduction of solid phase stress and strain. Presence of the labrum did not significantly influence fluid load support within the articular cartilage, but prevented deformation at the cartilage edge, leading to lower stress and strain conditions in the cartilage. A morphologically accurate representation of collagen fibril orientation through the thickness of the articular cartilage was not necessary to predict fluid load support. However, comparison with simplified fibril reinforcement underscored the physiological importance. The results of this study demonstrate that an elastic incompressible material approximation is reasonable for modeling a limited number of cyclic motions of gait and squatting without significant loss of accuracy, but is not appropriate for static motions or numerous repeated motions. Additionally, effects seen from removal of the labrum motivate evaluation of labral reattachment strategies in the context of labral repair.

Joint contact stress improves in dysplastic hips after periacetabular osteotomy but remains higher than in normal hips

“…8,11,12,17 Our higher stress magnitudes can be attributed to our effort to create a more realistic, nonuniform thickness cartilage layer, which has been shown to substantially affect computed joint mechanics. 22,30,31 This approach differs substantially from the thicker cartilage and more spherical articulations that have been assumed in many previous studies. 10,11,17 Interestingly, our results using patient-specific DEA compare extremely well with results from studies that utilised finite element (FE) analysis, a more sophisticated computational modelling technique that permits incorporation of multiple tissue types, advanced material properties, and provides continuum mechanics output information.…”

How Does Chondrolabral Damage and Labral Repair Influence the Mechanics of the Hip in the Setting of Cam Morphology? A Finite-Element Modeling Study

“…The mechanical contribution of the collagen fibrils was represented by a continuous fibril distribution constitutive model, which varied in its primary orientation through the thickness of the cartilage layers (Supplementary Digital Content 1, http://links.lww.com/CORR/A631). Material coefficients were set as in a previous study [58].…”

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.…”