Two different correlations between nanoindentation modulus and mineral content in the bone-cartilage interface.

The biomechanical properties of the zone of calcified cartilage (ZCC) in articulating joints are of clinical relevance due to the role ZCC plays in load transfer from cartilage to bone. To determine the micron-level mechanical properties and their correlation to mineral concentration in the ZCC, we combined nanoindentation (for micrometer level stiffness E(r) and hardness H) and quantitative back-scattered electron imaging or qBEI (for micrometer level mean calcium concentration Ca(Mean)) to study the ZCC-subchondral bone junction in 3 embedded human patellae. Nanoindentation line scans were correlated to qBEI analysis in the ZCC. The correlation between local stiffness and local mineral content was different in calcified cartilage compared to bone. The stiffness and hardness of calcified cartilage was typically lower than subchondral bone for the same mineral content. ZCC showed a wider range of variation in calcium content (1-28 wt %) compared to subchondral bone (16-26 wt %). 2D material property maps of the ZCC were generated from the mechanical-mineral correlation, showing that bands of high and low stiffness were found between the bone and tidemark, and between the ZCC and the unmineralized cartilage.

[1]  J Y Rho,et al.  Anisotropic properties of human tibial cortical bone as measured by nanoindentation , 2002, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[2]  G. Pharr,et al.  Indentation of elastically anisotropic half-spaces by cones and parabolae of revolution , 2001 .

[3]  W. Landis,et al.  A study of the relationship between mineral content and mechanical properties of turkey gastrocnemius tendon , 1995, Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research.

[4]  K. Abendroth,et al.  Analyses of the tidemark on human femoral heads. I. Histochemical, ultrastructural and microanalytic characterization of the normal structure of the intercartilaginous junction. , 1989, Acta morphologica Hungarica.

[5]  P Zioupos,et al.  Mechanical properties and the hierarchical structure of bone. , 1998, Medical engineering & physics.

[6]  Peter Fratzl,et al.  Cellulose and collagen: from fibres to tissues , 2003 .

[7]  S. Goldstein,et al.  Elastic modulus and hardness of cortical and trabecular bone lamellae measured by nanoindentation in the human femur. , 1999, Journal of biomechanics.

[8]  P. Fratzl,et al.  Characteristics of mineral particles in the human bone/cartilage interface. , 2003, Journal of structural biology.

[9]  H. Plenk,et al.  Formation of Ultracracks in Methacrylate-Embedded Undecalcified Bone Samples by Exposure to Aqueous Solutions , 1993 .

[10]  Stephen A. Wainwright,et al.  Mechanical Design in Organisms , 2020 .

[11]  K. Bachus,et al.  Determining mineral content variations in bone using backscattered electron imaging. , 1997, Bone.

[12]  J. Lewis,et al.  Elastic modulus of calcified cartilage is an order of magnitude less than that of subchondral bone , 1994, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[13]  N. Broom,et al.  Dynamic fracture characteristics of the osteochondral junction undergoing shear deformation. , 1996, Medical engineering & physics.

[14]  H. Plenk,et al.  A new scanning electron microscopy approach to the quantification of bone mineral distribution: backscattered electron image grey-levels correlated to calcium K alpha-line intensities. , 1995, Scanning microscopy.

[15]  J. Rho,et al.  Effects of viscoelasticity and time-dependent plasticity on nanoindentation measurements of human cortical bone. , 2003, Journal of biomedical materials research. Part A.

[16]  G. Pharr,et al.  Elastic properties of human cortical and trabecular lamellar bone measured by nanoindentation. , 1997, Biomaterials.

[17]  V. Mow,et al.  The ultrastructure and biomechanical significance of the tidemark of articular cartilage. , 1975, Clinical orthopaedics and related research.

[18]  D. Carter,et al.  Articular cartilage functional histomorphology and mechanobiology: a research perspective. , 2003, Bone.

[19]  A. M. Ahmed,et al.  Force analysis of the patellar mechanism , 1987, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[20]  G. Pharr,et al.  Effects of anisotropy on elastic moduli measured by nanoindentation in human tibial cortical bone. , 2001, Journal of biomedical materials research.

[21]  J. Currey.  Role of collagen and other organics in the mechanical properties of bone , 2003, Osteoporosis International.

[22]  P. Fratzl,et al.  Validation of quantitative backscattered electron imaging for the measurement of mineral density distribution in human bone biopsies. , 1998, Bone.

[23]  L. Sokoloff.  Microcracks in the calcified layer of articular cartilage. , 1993, Archives of pathology & laboratory medicine.

[24]  P. Fratzl,et al.  Constant mineralization density distribution in cancellous human bone. , 2003, Bone.

[25]  Himadri S. Gupta,et al.  Structure and mechanical quality of the collagen–mineral nano-composite in bone , 2004 .

[26]  L. Sokoloff,et al.  The osteochondral junction of mammalian joints. An ultrastructural and microanalytic study. , 1974, Laboratory investigation; a journal of technical methods and pathology.

[27]  K. Abendroth,et al.  Analyses of the tidemark on human femoral heads. II. Tidemark changes in osteoarthrosis--a histological and histomorphometric study in non-decalcified preparations. , 1989, Acta morphologica Hungarica.

[28]  P. Fratzl,et al.  Mineralized collagen fibrils: a mechanical model with a staggered arrangement of mineral particles. , 2000, Biophysical journal.

[29]  S. J. Jones,et al.  Scanning electron microscopy of bone: Instrument, specimen, and issues , 1996, Microscopy research and technique.

[30]  R Huiskes,et al.  The biomechanics of the human patella during passive knee flexion. , 1995, Journal of biomechanics.

[31]  Huajian Gao,et al.  Materials become insensitive to flaws at nanoscale: Lessons from nature , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[32]  G. Pharr,et al.  Variations in the individual thick lamellar properties within osteons by nanoindentation. , 1999, Bone.

[33]  S. Tsai,et al.  Introduction to composite materials , 1980 .

[34]  A. Boyde,et al.  Nanomechanical properties and mineral concentration in articular calcified cartilage and subchondral bone , 2003, Journal of anatomy.

[35]  K. O'Connor.  Unweighting Accelerates Tidemark Advancement in Articular Cartilage at the Knee Joint of Rats , 1997, Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research.

[36]  Steve Weiner,et al.  THE MATERIAL BONE: Structure-Mechanical Function Relations , 1998 .

[37]  S A Goldstein,et al.  Mechanical properties of human trabecular bone lamellae quantified by nanoindentation. , 1998, Technology and health care : official journal of the European Society for Engineering and Medicine.

[38]  G. Pharr,et al.  An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments , 1992 .

[39]  John D Currey,et al.  Tensile yield in compact bone is determined by strain, post-yield behaviour by mineral content. , 2004, Journal of biomechanics.

[40]  N. Broom,et al.  A functional-morphological study of the tidemark region of articular cartilage maintained in a non-viable physiological condition. , 1982, Journal of anatomy.

[41]  P J Basser,et al.  Mechanical properties of the collagen network in human articular cartilage as measured by osmotic stress technique. , 1998, Archives of biochemistry and biophysics.

[42]  W. Landis.  The strength of a calcified tissue depends in part on the molecular structure and organization of its constituent mineral crystals in their organic matrix. , 1995, Bone.