Mineral Distributions at the Developing Tendon Enthesis

Tendon attaches to bone across a functionally graded interface, “the enthesis”. A gradient of mineral content is believed to play an important role for dissipation of stress concentrations at mature fibrocartilaginous interfaces. Surgical repair of injured tendon to bone often fails, suggesting that the enthesis does not regenerate in a healing setting. Understanding the development and the micro/nano-meter structure of this unique interface may provide novel insights for the improvement of repair strategies. This study monitored the development of transitional tissue at the murine supraspinatus tendon enthesis, which begins postnatally and is completed by postnatal day 28. The micrometer-scale distribution of mineral across the developing enthesis was studied by X-ray micro-computed tomography and Raman microprobe spectroscopy. Analyzed regions were identified and further studied by histomorphometry. The nanometer-scale distribution of mineral and collagen fibrils at the developing interface was studied using transmission electron microscopy (TEM). A zone (∼20 µm) exhibiting a gradient in mineral relative to collagen was detected at the leading edge of the hard-soft tissue interface as early as postnatal day 7. Nanocharacterization by TEM suggested that this mineral gradient arose from intrinsic surface roughness on the scale of tens of nanometers at the mineralized front. Microcomputed tomography measurements indicated increases in bone mineral density with time. Raman spectroscopy measurements revealed that the mineral-to-collagen ratio on the mineralized side of the interface was constant throughout postnatal development. An increase in the carbonate concentration of the apatite mineral phase over time suggested possible matrix remodeling during postnatal development. Comparison of Raman-based observations of localized mineral content with histomorphological features indicated that development of the graded mineralized interface is linked to endochondral bone formation near the tendon insertion. These conserved and time-varying aspects of interface composition may have important implications for the growth and mechanical stability of the tendon-to-bone attachment throughout development.

[1]  Michael D Morris,et al.  Repeated freeze-thawing of bone tissue affects Raman bone quality measurements. , 2011, Journal of biomedical optics.

[2]  A. Boskey,et al.  Spatial Variation in Osteonal Bone Properties Relative to Tissue and Animal Age , 2009, Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research.

[3]  Stavros Thomopoulos,et al.  Variation of biomechanical, structural, and compositional properties along the tendon to bone insertion site. , 2003, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[4]  F A Matsen,et al.  Repairs of the rotator cuff. Correlation of functional results with integrity of the cuff. , 1991, The Journal of bone and joint surgery. American volume.

[5]  P. Fratzl,et al.  Two different correlations between nanoindentation modulus and mineral content in the bone-cartilage interface. , 2005, Journal of structural biology.

[6]  Michael D Morris,et al.  Raman Assessment of Bone Quality , 2011, Clinical orthopaedics and related research.

[7]  S. Judex,et al.  Accretion of Bone Quantity and Quality in the Developing Mouse Skeleton , 2007, Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research.

[8]  Joseph M. Wallace,et al.  Exercise Alters Mineral and Matrix Composition in the Absence of Adding New Bone , 2008, Cells Tissues Organs.

[9]  Stavros Thomopoulos,et al.  The Tendon-to-Bone Transition of the Rotator Cuff: A Preliminary Raman Spectroscopic Study Documenting the Gradual Mineralization across the Insertion in Rat Tissue Samples , 2008, Applied spectroscopy.

[10]  Sonja Gamsjaeger,et al.  Cortical bone composition and orientation as a function of animal and tissue age in mice by Raman spectroscopy. , 2010, Bone.

[11]  D. E. Ashhurst,et al.  Fetal and postnatal development of the patella, patellar tendon and suprapatella in the rabbit; changes in the distribution of the fibrillar collagens , 1997, Journal of anatomy.

[12]  Randy L Johnson,et al.  Bone ridge patterning during musculoskeletal assembly is mediated through SCX regulation of Bmp4 at the tendon-skeleton junction. , 2009, Developmental cell.

[13]  Stavros Thomopoulos,et al.  Decreased muscle loading delays maturation of the tendon enthesis during postnatal development , 2007, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[14]  Shenggang Liu,et al.  Temperature-dependent Raman spectra of collagen and DNA. , 2004, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.

[15]  G. Genin,et al.  The nanometre-scale physiology of bone: steric modelling and scanning transmission electron microscopy of collagen–mineral structure , 2012, Journal of The Royal Society Interface.

[16]  R. Zernicke,et al.  Structure, function and adaptation of bone-tendon and bone-ligament complexes. , 2005, Journal of musculoskeletal & neuronal interactions.

[17]  William F. Finney,et al.  Bone tissue compositional differences in women with and without osteoporotic fracture. , 2006, Bone.

[18]  Victor Birman,et al.  Collagen fiber orientation at the tendon to bone insertion and its influence on stress concentrations. , 2006, Journal of biomechanics.

[19]  G. Breur,et al.  Linear relationship between the volume of hypertrophic chondrocytes and the rate of longitudinal bone growth in growth plates , 1991, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[20]  William D Middleton,et al.  The outcome and repair integrity of completely arthroscopically repaired large and massive rotator cuff tears. , 2004, The Journal of bone and joint surgery. American volume.

[21]  J. Ralphs,et al.  The skeletal attachment of tendons--tendon "entheses". , 2002, Comparative biochemistry and physiology. Part A, Molecular & integrative physiology.

[22]  Stavros Thomopoulos,et al.  Development of the supraspinatus tendon‐to‐bone insertion: Localized expression of extracellular matrix and growth factor genes , 2007, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[23]  A. Boskey,et al.  Microstructure and nanomechanical properties in osteons relate to tissue and animal age. , 2011, Journal of biomechanics.

[24]  Min Wei,et al.  Spectrochimica Acta Part A : Molecular and Biomolecular Spectroscopy , 2013 .

[25]  Gerard A Ateshian,et al.  Characterization of the structure–function relationship at the ligament-to-bone interface , 2008, Proceedings of the National Academy of Sciences.

[26]  K. Messner,et al.  An immunohistochemical study of enthesis development in the medial collateral ligament of the rat knee joint , 1996, Anatomy and Embryology.

[27]  L. Soslowsky,et al.  Tendon to bone healing: differences in biomechanical, structural, and compositional properties due to a range of activity levels. , 2003, Journal of biomechanical engineering.

[28]  Victor Birman,et al.  Mechanisms of Bimaterial Attachment at the Interface of Tendon to Bone. , 2011, Journal of engineering materials and technology.

[29]  M. Benjamin,et al.  The anatomical basis for disease localisation in seronegative spondyloarthropathy at entheses and related sites , 2001, Journal of anatomy.

[30]  S. Misol,et al.  Tendon and ligament insertion. A light and electron microscopic study. , 1970, The Journal of bone and joint surgery. American volume.

[31]  T. H. Haut Donahue,et al.  Nanoindentation of the insertional zones of human meniscal attachments into underlying bone. , 2009, Journal of the mechanical behavior of biomedical materials.

[32]  A. Boskey,et al.  Contribution of Mineral to Bone Structural Behavior and Tissue Mechanical Properties , 2010, Calcified Tissue International.

[33]  J. Hermanson,et al.  Postnatal Bone Elongation of the Manus versus Pes: Analysis of the Chondrocytic Differentiation Cascade in Mus musculus and Eptesicus fuscus , 2007, Cells Tissues Organs.

[34]  J. C. Vuletin,et al.  A Light and Electron Microscopic Study , 1976 .

[35]  E. Mackie,et al.  Endochondral ossification: how cartilage is converted into bone in the developing skeleton. , 2008, The international journal of biochemistry & cell biology.

[36]  Victor Birman,et al.  Functional grading of mineral and collagen in the attachment of tendon to bone. , 2009, Biophysical journal.

[37]  R. Egerton,et al.  Electron Energy-Loss Spectroscopy in the Electron Microscope , 1995, Springer US.

[38]  Matthew J. Silva,et al.  Decreased Collagen Organization and Content Are Associated With Reduced Strength of Demineralized and Intact Bone in the SAMP6 Mouse , 2005, Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research.

[39]  P. Claudepierre,et al.  The entheses: histology, pathology, and pathophysiology. , 2004, Joint, bone, spine : revue du rhumatisme.

[40]  I. E. Wang,et al.  Age‐dependent changes in matrix composition and organization at the ligament‐to‐bone insertion , 2006, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[41]  Michael D. Morris,et al.  Carbonate Assignment and Calibration in the Raman Spectrum of Apatite , 2007, Calcified Tissue International.

[42]  Eve Donnelly,et al.  Effects of tissue age on bone tissue material composition and nanomechanical properties in the rat cortex. , 2009, Journal of biomedical materials research. Part A.

[43]  E. Olson,et al.  Coordinated expression of scleraxis and Sox9 genes during embryonic development of tendons and cartilage , 2002, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[44]  I. Stokes,et al.  Growth plate mechanics and mechanobiology. A survey of present understanding. , 2009, Journal of biomechanics.

[45]  James Sharpe,et al.  Mechanobiology of embryonic skeletal development: Insights from animal models. , 2010, Birth defects research. Part C, Embryo today : reviews.

[46]  Kimimitsu Oda,et al.  Histology of epiphyseal cartilage calcification and endochondral ossification. , 2012, Frontiers in bioscience.

[47]  Michael D Morris,et al.  Mineralization of Developing Mouse Calvaria as Revealed by Raman Microspectroscopy , 2002, Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research.

[48]  G. Genin,et al.  Bi-material attachment through a compliant interfacial system at the tendon-to-bone insertion site. , 2012, Mechanics of materials : an international journal.

[49]  D. Keene,et al.  Transmission electron microscopy of cartilage and bone. , 2010, Methods in cell biology.

[50]  H. Fujioka,et al.  Changes in the expression of type‐X collagen in the fibrocartilage of rat Achilles tendon attachment during development , 1997, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[51]  L. Galatz,et al.  The localized expression of extracellular matrix components in healing tendon insertion sites: an in situ hybridization study , 2002, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[52]  J. Ralphs,et al.  Fibrocartilage in tendons and ligaments — an adaptation to compressive load , 1998, Journal of anatomy.

[53]  M. Glimcher,et al.  Electron microscopic observations of bone tissue prepared by ultracryomicrotomy. , 1977, Journal of ultrastructure research.