Anisotropic response of the human knee joint meniscus to unconfined compression

Leslie, Ben; Gardner, D L; McGeough, J. A.; Moran, R

doi:10.1243/0954411001535651

Cited by 47 publications

(27 citation statements)

References 13 publications

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“…Meniscal lesions alone are responsible for nearly 1 million surgeries annually in the U.S. and Europe, and are the root cause of the most frequent procedures practiced by orthopedic surgeons [5, 6]. The knee meniscus displays a specific, functionally important wedge shape, as well as mechanical anisotropy between its circumferential and radial directions [7–9]. This very specific organization allows the knee meniscus to effectively transfer loading from the distal femur to the tibial plateau [10].…”

Section: Introductionmentioning

confidence: 99%

Critical seeding density improves the properties and translatability of self-assembling anatomically shaped knee menisci

Hadidi

Yeh

et al. 2015

Acta Biomaterialia

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A recent development in the field of tissue engineering is the rise of all-biologic, scaffold-free engineered tissues. Since these biomaterials rely primarily upon cells, investigation of initial seeding densities constitutes a particularly relevant aim for tissue engineers. In this study, a scaffold-free method was used to create fibrocartilage in the shape of the rabbit knee meniscus. The objectives of this study were: (i) to determine the minimum seeding density, normalized by an area of 44 mm2, necessary for the self-assembling process of fibrocartilage to occur, (ii) examine relevant biomechanical properties of engineered fibrocartilage, such as tensile and compressive stiffness and strength, and their relationship to seeding density, and (iii) identify a reduced, or optimal, number of cells needed to produce this biomaterial. It was found that a decreased initial seeding density, normalized by the area of the construct, produced superior mechanical and biochemical properties. Collagen per wet weight, glycosaminoglycans per wet weight, tensile properties, and compressive properties were all significantly greater in the 5 million cells per construct group as compared to the historical 20 million cells per construct group. Scanning electron microscopy demonstrated that a lower seeding density results in a denser tissue. Additionally, the translational potential of the self-assembling process for tissue engineering was improved though this investigation, as fewer cells may be used in the future. The results of this study underscore the potential for critical seeding densities to be investigated when researching scaffold-free engineered tissues.

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Section: Introductionmentioning

confidence: 99%

Critical seeding density improves the properties and translatability of self-assembling anatomically shaped knee menisci

Hadidi

Yeh

et al. 2015

Acta Biomaterialia

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“…In contrast, the radial fibers are a co-localization of type I and II collagens arranged in ~10 μm parallel bundles (Rattner, et al, 2010, Skaggs, et al, 1994). This morphology evokes an anisotropic material response relative to collagen fibril orientations (Anderson, et al, 1991, Bursac, et al, 2009, Fithian, et al, 1990, Leslie, et al, 2000, Proctor, et al, 1989, Zhu, et al, 1994). …”

Section: Introductionmentioning

confidence: 99%

Regional and fiber orientation dependent shear properties and anisotropy of bovine meniscus

Abraham

Edwards

Odegard

et al. 2011

Journal of the Mechanical Behavior of Biomedical Materials

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Imaging of meniscal tissue reveals an extracellular matrix comprised of collagen fibrils arranged in circumferential bundles and radially aligned tie fibers, implicating structural material anisotropy. Biochemical analyses demonstrate regional disparities of proteoglycan content throughout the meniscal body, a constituent known to affect the shearing response of fibrocartilagenous tissue. Despite this phenomenological evidence and previous mechanical testing implicating otherwise, the meniscus if often modeled as a homogenous, transversely isotropic material with little regard for regional specificity and material properties. The aim of this investigation was to determine if shear stress response homogeneity and directionality exists in and between bovine menisci with respect to anatomical location (medial and lateral), region (anterior, central, and posterior) and fiber orientation (parallel and perpendicular). Meniscus explants were subjected to lap shear strain at 0.002 sec−1 with the circumferential collagen fibers oriented parallel or perpendicular to the loading axis. Comparisons were made using a piecewise linear elastic analysis. The toe region shear modulus was calculated from the first observed linear region, between 3%-13% strain and the extended shear modulus was established after 80% of the maximum shear strain. The posterior region was significantly different than the central for the extended shear modulus, correlating with known proteoglycan distribution. Observed shearing anisotropy led to the use of an anisoptropic hyperelastic model based on a two-fiber family composite, previously used for arterial walls. The chosen model provided an excellent fit to the sample population for each region. These data can be utilized in the advancement of finite element modeling as well as biomimetic tissue engineered constructs.

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“…In meniscus, the superficial zone is characterized by a fine mesh of randomly oriented collagen fibrils lying above a lamellar layer of collagen fibril bundles[6], while the interior of the tissue consists of bundles of circumferentially oriented collagen I fibers surrounded by a secondary network composed of multiple collagen types and PGs[7–10]. The circumferentially oriented collagen fibers are responsible for sustaining high tensile hoop stresses due to compression and extrusion of the meniscus, and the density, orientation and distribution of the circumferential fibers strongly influences the macroscopic tensile, compressive and shear responses[3, 11–13]. …”

Section: Introductionmentioning

confidence: 99%

Meniscus and cartilage exhibit distinct intra-tissue strain distributions under unconfined compression

Lai

Levenston

2010

Osteoarthritis and Cartilage

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Objective To examine the functional behavior of the surface layer of the meniscus by investigating depth-varying compressive strains during unconfined compression. Design Pairs of meniscus and articular cartilage explants (n=12) site-matched at the tibial surfaces were subjected to equilibrium unconfined compression at 5, 10, 15, and 20% compression under fluorescence imaging. Two-dimensional deformations were tracked using digital image correlation. For each specimen, local compressive engineering strains were determined in 200μm layers through the depth of the tissue. In samples with sharp strain transitions, bi-linear regressions were used to characterize the surface and interior tissue compressive responses. Results Meniscus and cartilage exhibited distinct depth-dependent strain profiles during unconfined compression. All cartilage explants had elevated compressive engineering strains near the surface, consistent with previous reports. In contrast, half of the meniscus explants tested had substantially stiffer surface layers, as indicated by surface engineering strains that were ~20% of the applied compression. In the remaining samples, surface and interior engineering strains were comparable. Two-dimensional Green's strain maps revealed highly heterogeneous compressive and shear strains throughout the meniscus explants. In cartilage, the maximum shear strain appeared to be localized at 100–250μm beneath the articular surface. Conclusions Meniscus was characterized by highly heterogeneous strains during compression. In contrast to cartilage, which consistently had a compliant surface region, meniscal explants were either substantially stiffer near the surface or had comparable compressive stiffness through the depth. The relatively compliant interior may allow the meniscus to maintain a consistent surface contour while deforming during physiologic loading.

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Anisotropic response of the human knee joint meniscus to unconfined compression

Cited by 47 publications

References 13 publications

Critical seeding density improves the properties and translatability of self-assembling anatomically shaped knee menisci

Critical seeding density improves the properties and translatability of self-assembling anatomically shaped knee menisci

Regional and fiber orientation dependent shear properties and anisotropy of bovine meniscus

Meniscus and cartilage exhibit distinct intra-tissue strain distributions under unconfined compression

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