Enthesis; Mineralized fibrocartilage; Nanoindentation; Quantitative backscattered electron imaging; Second harmonic generation imaging; Minerals; Animals; Rats; Bone and Bones; Fibrocartilage; Achilles Tendon; Achilles tendons; Backscattered electron imaging; Harmonic generation imaging; Mineral content; Nano indentation; Biotechnology; Biomaterials; Biochemistry; Biomedical Engineering; Molecular Biology; General Medicine
Abstract :
[en] A demanding task of the musculoskeletal system is the attachment of tendon to bone at entheses. This region often presents a thin layer of fibrocartilage (FC), mineralized close to the bone and unmineralized close to the tendon. Mineralized FC deserves increased attention, owing to its crucial anchoring task and involvement in enthesis pathologies. Here, we analyzed mineralized FC and subchondral bone at the Achilles tendon-bone insertion of rats. This location features enthesis FC anchoring tendon to bone and sustaining tensile loads, and periosteal FC facilitating bone-tendon sliding with accompanying compressive and shear forces. Using a correlative multimodal investigation, we evaluated potential specificities in mineral content, fiber organization and mechanical properties of enthesis and periosteal FC. Both tissues had a lower degree of mineralization than subchondral bone, yet used the available mineral very efficiently: for the same local mineral content, they had higher stiffness and hardness than bone. We found that enthesis FC was characterized by highly aligned mineralized collagen fibers even far away from the attachment region, whereas periosteal FC had a rich variety of fiber arrangements. Except for an initial steep spatial gradient between unmineralized and mineralized FC, local mechanical properties were surprisingly uniform inside enthesis FC while a modulation in stiffness, independent from mineral content, was observed in periosteal FC. We interpreted these different structure-property relationships as a demonstration of the high versatility of FC, providing high strength at the insertion (to resist tensile loading) and a gradual compliance at the periosteal surface (to resist contact stresses). STATEMENT OF SIGNIFICANCE: Mineralized fibrocartilage (FC) at entheses facilitates the integration of tendon in bone, two strongly dissimilar tissues. We focus on the structure-function relationships of two types of mineralized FC, enthesis and periosteal, which have clearly distinct mechanical demands. By investigating them with multiple high-resolution methods in a correlative manner, we demonstrate differences in fiber architecture and mechanical properties between the two tissues, indicative of their mechanical roles. Our results are relevant both from a medical viewpoint, targeting a clinically relevant location, as well as from a material science perspective, identifying FC as high-performance versatile composite.
Disciplines :
Engineering, computing & technology: Multidisciplinary, general & others
Author, co-author :
Tits, Alexandra ; Université de Liège - ULiège > Aérospatiale et Mécanique (A&M)
Blouin, Stéphane ; Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria
Rummler, Maximilian ; Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
Kaux, Jean-François ; Centre Hospitalier Universitaire de Liège - CHU > > Service de médecine de l'appareil locomoteur
Drion, Pierre ; Université de Liège - ULiège > GIGA > GIGA Research (AFT)
van Lenthe, G Harry ; Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
Weinkamer, Richard ; Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
Hartmann, Markus A ; Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria
Ruffoni, Davide ; Université de Liège - ULiège > Département d'aérospatiale et mécanique > Mécanique des matériaux biologiques et bioinspirés
Language :
English
Title :
Structural and functional heterogeneity of mineralized fibrocartilage at the Achilles tendon-bone insertion.
AT is a FRIA (Fund for Research Training in Industry and Agriculture ) grant holder (n° 5129219F ). We warmly thank Luc Duwez from University of Liege, GIGA, for his essential help with sample extraction. We wish to thank Petra Keplinger, Sonja Lueger and Phaedra Messmer from LBIO for the excellent sample preparation. MH and SB are grateful for financial support from the AUVA (Research funds of the Austrian workers’ compensation board) and OEGK (Austrian Social Health Insurance Fund). MR and RW acknowledge support from the Max Planck Queensland centre for the Materials Science of Extracellular Matrices.AT is a FRIA (Fund for Research Training in Industry and Agriculture) grant holder (n°5129219F). We warmly thank Luc Duwez from University of Liege, GIGA, for his essential help with sample extraction. We wish to thank Petra Keplinger, Sonja Lueger and Phaedra Messmer from LBIO for the excellent sample preparation. MH and SB are grateful for financial support from the AUVA (Research funds of the Austrian workers’ compensation board) and OEGK (Austrian Social Health Insurance Fund). MR and RW acknowledge support from the Max Planck Queensland centre for the Materials Science of Extracellular Matrices.
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