Stress distributions and material properties determined in articular cartilage from MRI-based finite strains

Functional imaging in OA: role of imaging in the evaluation of tissue biomechanics

“…A large number of MRI- and ultrasound-based techniques are available to map displacements and strain at high resolution, which are then coupled to material models to estimate stress [122] or material properties [123–126], most often classified as elastography [127]. Because the material properties of cartilage change in OA [8], controlled magnitudes of ex vivo or in vivo mechanical loading would likely result in aberrant deformation for progressively diseased tissue, suggesting that displacement or strain alone may be a sufficiently unique functional measure.…”

“…Unfortunately, conventional MR elastography for cartilage [125] is not yet easily adapted for in vivo imaging because of challenges in visualizing small, high frequency loading in thin (<3 mm thick) cartilage that is deeply embedded within the joint. As a result, high resolution measures of strain have instead been coupled to materials models for joint imaging [122]. …”

“…The high displacement and strain precision of dualMRI (on the order of 11 μm and 0.1%, respectively [2]) suggests that the technique is highly sensitive to measure small local changes in cartilage strain during OA that indicate altered stiffness and degenerative changes. The deformation data has permitted the description of cartilage strain in OA [66], repair models [135], intact joints [136], and in relation to stress and material properties [122]. Moreover, the fast acquisition of the dualMRI data has permitted direct measurement of cartilage strain in vivo on clinical MRI systems for the first time [137], hinting at the future possibility for human studies of joint disease and repair.…”

In VivoCellular Infiltration and Remodeling in a Decellularized Ovine Osteochondral Allograft

“…noninvasive mechanical (i.e., functional) analysis 35,36 would remain indifferent to responses from treatment groups, as the sensitivity of qMRI for small population sizes, like what was studied here, has been questioned. 26 In some samples, decellularized cartilage in the proximal location appeared, by MRI, more similar to empty defects, suggesting a locationdependent bias for cartilage repair.…”

Finite element modeling in the musculoskeletal system: generic overview

“…The cartilage deformations could be roughly measured non-invasively using displacement encoded MR imaging (Neu and Walton, 2008;Chan et al ., 2009). Based on the measured strain and stress patterns, the intrinsic properties of the cartilage could be derived through computational analyses (Butz et al ., 2011). Very recently, fi bril-reinforced poroviscoelastic material properties with depth dependent collagen orientations and split-line patterns were used to simulate cartilage for FE knee joint modeling (Mononen et al ., 2012).…”