Deformation and failure of cartilage in the tensile mode

Abstract

The aim of this study was to visualize, at the ultrastructural level, the deformation and failure mechanism of cartilage matrix in the tensile mode. Full-thickness dumbbell-shaped specimens were prepared from adult bovines.There were two specimen groups; in the 'parallel' group the specimen axis was parallel to the split lines defining the preferential orientation of the collagen in the articular surface, and in the 'perpendicular' group the specimen axis was perpendicular to the split lines. Specimens were placed with the articular surface uppermost and subjected to a graded series of strain within individual mini-tension devices, while observed with stereomicroscopy and confocal laser scanning microscopy. Thereafter, the changes in the ultrastructure were observed with both scanning and transmission electron microscopy. The mechanism of cartilage failure in the tensile mode comprised the following stages, whether the strain was applied parallel or perpendicular to the split line. (1) At 0% strain a fibrillar meshwork within the articular surface was predominantly orientated in the direction of the split line. (2) As strain increased, the fibrillar meshwork became more orientated in the parallel group and reorientated in the perpendicular group in the direction of the applied strain. (3) After complete reorientation of the fibrillar meshwork in the direction of the applied strain, the initial sign of failure was rupture of the fibrillar meshwork within the articular surface. (4) Subsequently, the rupture rapidly propagated into the deeper layers. Greater strains were required for fibrillar reorientation and complete rupture in the 'perpendicular group' than in the parallel group.

Quantitative Evaluation of the Mechanical Risks Caused by Focal Cartilage Defects in the Knee

“…6a), a small area with elevated stress was observed at the defect rim. The absolute values at this area exceeded a suggested cartilage failure limit of 7 MPa1843 during the peak loads of the stance (approximately at 10–30% and 80–90% of the stance). At other time points, the stresses were found to be well below the suggested failure limit.…”

“…During those time periods, they reached levels that could induce either chondrocyte death46 or failure of collagen crosslinks47. Furthermore, the stress concentrations on the defect rim at peak loads could also imply the initiation of collagen matrix degeneration in the superficial layers of the tissue1843. Exceeding the suggested failure limits of any of these parameters could lead to propagation of the defect and OA.…”

Photo-cross-linked methacrylated polysaccharide solution blends with high chondrocyte viability, minimal swelling, and moduli similar to load bearing soft tissues

“…For example, Park et al reported physiological strains of 20% for native cartilage under normal loading conditions [40]. Failure strain and stress of cartilage in tension tested at 1%/s strain rate was reported between 25% and 30% and approximately 3-5 MPa, respectively [41]. Kaukinen et al reported destructive compressive stress and strain values for cartilage-bone plugs of 4.6 ± 2.0 MPa and 50 ± 6% when tested at 3.5%/s strain rate [42].…”

Effects of glenoid inclination and acromion index on humeral head translation and glenoid articular cartilage strain

“…The maximum strain (26%) and reference strain (14.3%) were, however, both below the reported critical strain. 9,23,35 The supraspinatus was the most sensitive muscle to the 2 anatomic parameters. As expected, GI had a smaller effect on supraspinatus forces than AI and consequently on glenohumeral joint forces.…”