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Couppé C, Svensson RB, Skovlund SV, Jensen JK, Eriksen CS, Malmgaard-Clausen NM, Nybing JD, Kjaer M, Magnusson SP. Habitual side-specific loading leads to structural, mechanical and compositional changes in the patellar tendon of young and senior life-long male athletes. J Appl Physiol (1985) 2021; 131:1187-1199. [PMID: 34382838 DOI: 10.1152/japplphysiol.00202.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Effects of life-long physical activity on tendon function have been investigated in cross-sectional studies, but these are at risk of "survivorship" bias. Here, we investigate if life-long side-specific loading is associated with greater cross-sectional area (CSA), mechanical properties, cell density (DNA content) and collagen cross-link composition of the male human patellar tendon (PT), in vivo. Nine seniors and six young male life-long elite badminton players and fencers were included. CSA of the PT obtained by 3-tesla MRI, and ultrasonography-based bilateral PT mechanics were assessed. Collagen fibril characteristics, enzymatic cross-links, non-enzymatic glycation (autofluorescence), collagen and DNA content were measured biochemically in PT biopsies. The elite athletes had a ≥15% side-to-side difference in maximal knee extensor strength, reflecting chronic unilateral sport-specific loading patterns. The PT CSA was greater on the lead extremity compared with the non-lead extremity (17 %, p=0.0001). Furthermore, greater tendon stiffness (18 %, p=0.0404) together with lower tendon stress (22 %, p=0.0005) and tendon strain (18 %, p=0.0433) were observed on the lead extremity. No effects were demonstrated from side-to-side for glycation, enzymatic cross-link, collagen, and DNA content (50%, p=0.1160). Moreover, tendon fibril density was 87±28 fibrils/μm2 on the lead extremity and 68±26 fibrils/μm2 on the non-lead extremity (28%, p=0.0544). Tendon fibril diameter was 86±14 nm on the lead extremity and 94±14 nm on the non-lead extremity (-9%, p=0.1076). These novel data suggest that life-long side-specific loading in males yields greater patellar tendon size and stiffness possibly with concomitant greater fibril density but without changes of collagen cross-link composition.
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Affiliation(s)
- Christian Couppé
- Institute of Sports Medicine Copenhagen, Bispebjerg-Frederiksberg Hospitals, Denmark.,Department of Physical and Occupational Therapy, Bispebjerg-Frederiksberg Hospitals, Denmark
| | - Rene B Svensson
- Institute of Sports Medicine Copenhagen, Bispebjerg-Frederiksberg Hospitals, Denmark
| | - Sebastian V Skovlund
- Institute of Sports Medicine Copenhagen, Bispebjerg-Frederiksberg Hospitals, Denmark.,Department of Physical and Occupational Therapy, Bispebjerg-Frederiksberg Hospitals, Denmark
| | | | | | | | - Janus Damm Nybing
- Department of Radiology, Bispebjerg-Frederiksberg Hospitals, Denmark
| | - Michael Kjaer
- Institute of Sports Medicine Copenhagen, Bispebjerg-Frederiksberg Hospitals, Denmark
| | - S Peter Magnusson
- Institute of Sports Medicine Copenhagen, Bispebjerg-Frederiksberg Hospitals, Denmark.,Department of Physical and Occupational Therapy, Bispebjerg-Frederiksberg Hospitals, Denmark
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Cardona-Ramirez S, Stoker AM, Cook JL, Ma R. Fibroblasts From Common Anterior Cruciate Ligament Tendon Grafts Exhibit Different Biologic Responses to Mechanical Strain. Am J Sports Med 2021; 49:215-225. [PMID: 33259232 DOI: 10.1177/0363546520971852] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Different tendons are chosen for anterior cruciate ligament (ACL) reconstruction based on perceived advantages and disadvantages, yet there is a relative paucity of information regarding biologic responsiveness of commonly used tendon grafts to mechanical strain. PURPOSE To evaluate the in vitro responses of graft fibroblasts derived from tendons used for ACL reconstruction to clinically relevant strain levels. STUDY DESIGN Controlled laboratory study. METHODS Twelve quadriceps tendons (QTs), 12 patellar tendons (PTs), and 9 hamstring tendons (HTs) were harvested from skeletally mature dogs (n = 16). Tendon fibroblasts were isolated and seeded onto BioFlex plates (1 × 105 cells/well). Cells were subjected to 3 strain conditions (stress deprivation, 0%; physiologic, 4%; high, 10%) for 5 days. Media were collected for proinflammatory and metabolic assays. RNA was extracted for gene expression analysis using real-time reverse transcription polymerase chain reaction. RESULTS Stress deprivation elicited significantly higher metabolic activity from HT and PT cells than from QT cells (P < .001 and P = .001, respectively). There were no differences in metabolic activity among all 3 graft fibroblasts at physiologic and high strain. COL-1 expression was significantly higher in PT versus HT during physiologic strain (P = .007). No significant differences with COL-3 expression were seen. TIMP-1 (P = .01) expression was higher in PT versus HT under physiologic strain. Scleraxis expression was higher in PT versus HT (P = .007) under physiologic strain. A strain-dependent increase in PGE2 levels occurred for all grafts. At physiologic strain conditions, HT produced significantly higher levels of PGE2 versus QT (P < .001) and PT (P = .005). CONCLUSION Fibroblasts from common ACL graft tissues exhibited different metabolic responses to mechanical strain. On the basis of these data, we conclude that early production of extracellular matrix and proinflammatory responses from ACL grafts are dependent on mechanical loading and graft source. CLINICAL RELEVANCE Graft-specific differences in ACL reconstruction outcomes are known to exist. Our results suggest that there are differences in the biologic responsiveness of cells from the tendon grafts used in ACL reconstruction, which are dependent on strain levels and graft source. The biologic properties of the tissue used for ACL reconstruction should be considered when selecting graft source.
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Affiliation(s)
- Sebastian Cardona-Ramirez
- Department of Orthopaedic Surgery, Thompson Laboratory for Regenerative Orthopaedics, University of Missouri, Columbia, Missouri, USA
| | - Aaron M Stoker
- Department of Orthopaedic Surgery, Thompson Laboratory for Regenerative Orthopaedics, University of Missouri, Columbia, Missouri, USA
| | - James L Cook
- Department of Orthopaedic Surgery, Thompson Laboratory for Regenerative Orthopaedics, University of Missouri, Columbia, Missouri, USA
| | - Richard Ma
- Department of Orthopaedic Surgery, Thompson Laboratory for Regenerative Orthopaedics, University of Missouri, Columbia, Missouri, USA
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van Vijven M, van Groningen B, Kimenai JN, van der Steen MC, van Doeselaar M, Janssen RPA, Ito K, Foolen J. Identifying potential patient-specific predictors for anterior cruciate ligament reconstruction outcome - a diagnostic in vitro tissue remodeling platform. J Exp Orthop 2020; 7:48. [PMID: 32623555 PMCID: PMC7335379 DOI: 10.1186/s40634-020-00266-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/24/2020] [Indexed: 02/06/2023] Open
Abstract
Purpose Upon anterior cruciate ligament (ACL) rupture, reconstruction is often required, with the hamstring tendon autograft as most widely used treatment. Post-operative autograft remodeling enhances graft rupture risk, which occurs in up to 10% of the patient population, increasing up to 30% of patients aged under 20 years. Therefore, this research aimed to identify potential biological predictors for graft rupture, derived from patient-specific tissue remodeling-related cell properties in an in vitro micro-tissue platform. Methods Hamstring tendon-derived cells were obtained from remnant autograft tissue after ACL reconstructions (36 patients, aged 12–55 years), and seeded in collagen I gels on a micro-tissue platform. Micro-tissue compaction over time – induced by altering the boundary constraints – was monitored. Pro-collagen I expression was assessed using ELISA, and protein expression of tenomodulin and α-smooth muscle actin were measured using Western blot. Expression and activity of matrix metalloproteinase 2 were determined using gelatin zymography. Results Only micro-tissues corresponding to younger patients occasionally released themselves from the constraining posts. Pro-collagen I expression was significantly higher in younger patients. Differences in α-smooth muscle actin and tenomodulin expression between patients were found, but these were age-independent. Active matrix metalloproteinase 2 expression was slightly more abundant in younger patients. Conclusions The presented micro-tissue platform exposed patient-specific remodeling-related differences between tendon-derived cells, with the micro-tissues that released from constraining posts and pro-collagen I expression best reflecting the clinical age-dependency of graft rupture. These properties can be the starting point in the quest for potential predictors for identifying individual patients at risk for graft rupture.
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Affiliation(s)
- Marc van Vijven
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Building 15, Groene Loper, Gemini-Zuid 4.12, PO Box 513, 5600MB, Eindhoven, The Netherlands. .,Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands.
| | - Bart van Groningen
- Department of Orthopaedic Surgery, Máxima MC, Eindhoven, the Netherlands
| | - Joyce N Kimenai
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Building 15, Groene Loper, Gemini-Zuid 4.12, PO Box 513, 5600MB, Eindhoven, The Netherlands
| | - Maria C van der Steen
- Department of Orthopaedic Surgery, Máxima MC, Eindhoven, the Netherlands.,Department of Orthopaedic Surgery, Catharina Hospital Eindhoven, Eindhoven, the Netherlands
| | - Marina van Doeselaar
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Building 15, Groene Loper, Gemini-Zuid 4.12, PO Box 513, 5600MB, Eindhoven, The Netherlands
| | - Rob P A Janssen
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Building 15, Groene Loper, Gemini-Zuid 4.12, PO Box 513, 5600MB, Eindhoven, The Netherlands.,Department of Orthopaedic Surgery, Máxima MC, Eindhoven, the Netherlands.,Fontys University of Applied Sciences, Eindhoven, the Netherlands
| | - Keita Ito
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Building 15, Groene Loper, Gemini-Zuid 4.12, PO Box 513, 5600MB, Eindhoven, The Netherlands.,Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Jasper Foolen
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Building 15, Groene Loper, Gemini-Zuid 4.12, PO Box 513, 5600MB, Eindhoven, The Netherlands.,Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands
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4
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Zullo A, Fleckenstein J, Schleip R, Hoppe K, Wearing S, Klingler W. Structural and Functional Changes in the Coupling of Fascial Tissue, Skeletal Muscle, and Nerves During Aging. Front Physiol 2020; 11:592. [PMID: 32670080 PMCID: PMC7327116 DOI: 10.3389/fphys.2020.00592] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 05/11/2020] [Indexed: 12/18/2022] Open
Abstract
Aging is a one-way process associated with profound structural and functional changes in the organism. Indeed, the neuromuscular system undergoes a wide remodeling, which involves muscles, fascia, and the central and peripheral nervous systems. As a result, intrinsic features of tissues, as well as their functional and structural coupling, are affected and a decline in overall physical performance occurs. Evidence from the scientific literature demonstrates that senescence is associated with increased stiffness and reduced elasticity of fascia, as well as loss of skeletal muscle mass, strength, and regenerative potential. The interaction between muscular and fascial structures is also weakened. As for the nervous system, aging leads to motor cortex atrophy, reduced motor cortical excitability, and plasticity, thus leading to accumulation of denervated muscle fibers. As a result, the magnitude of force generated by the neuromuscular apparatus, its transmission along the myofascial chain, joint mobility, and movement coordination are impaired. In this review, we summarize the evidence about the deleterious effect of aging on skeletal muscle, fascial tissue, and the nervous system. In particular, we address the structural and functional changes occurring within and between these tissues and discuss the effect of inflammation in aging. From the clinical perspective, this article outlines promising approaches for analyzing the composition and the viscoelastic properties of skeletal muscle, such as ultrasonography and elastography, which could be applied for a better understanding of musculoskeletal modifications occurring with aging. Moreover, we describe the use of tissue manipulation techniques, such as massage, traction, mobilization as well as acupuncture, dry needling, and nerve block, to enhance fascial repair.
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Affiliation(s)
- Alberto Zullo
- Department of Sciences and Technologies, University of Sannio, Benevento, Italy
- CEINGE Advanced Biotechnologies, Naples, Italy
| | - Johannes Fleckenstein
- Department of Sports Medicine, Institute of Sports Sciences, Goethe-University Frankfurt, Frankfurt, Germany
| | - Robert Schleip
- Department of Sport and Health Sciences, Technical University Munich, Munich, Germany
- Department of Sports Medicine and Health Promotion, Friedrich-Schiller University Jena, Jena, Germany
| | - Kerstin Hoppe
- Department of Anaesthesiology, Würzburg University, Würzburg, Germany
| | - Scott Wearing
- Department of Sport and Health Sciences, Technical University Munich, Munich, Germany
- Faculty of Health School, Queensland University of Technology, Brisbane, QLD, Australia
| | - Werner Klingler
- Department of Sport and Health Sciences, Technical University Munich, Munich, Germany
- Faculty of Health School, Queensland University of Technology, Brisbane, QLD, Australia
- Fascia Research Group, Department of Experimental Anaesthesiology, Ulm University, Ulm, Germany
- Department of Anaesthesiology, SRH Hospital Sigmaringen, Sigmaringen, Germany
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5
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Ristaniemi A, Torniainen J, Stenroth L, Finnilä M, Paakkonen T, Töyräs J, Korhonen R. Comparison of water, hydroxyproline, uronic acid and elastin contents of bovine knee ligaments and patellar tendon and their relationships with biomechanical properties. J Mech Behav Biomed Mater 2020; 104:103639. [DOI: 10.1016/j.jmbbm.2020.103639] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 01/13/2020] [Accepted: 01/13/2020] [Indexed: 12/13/2022]
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Abstract
The hierarchical structure of tendon allows for attenuation of mechanical strain down decreasing length scales. While reorganization of collagen fibers accounts for microscale strain attenuation, cross-linking between collagen molecules contributes to deformation mechanisms at the fibrillar and molecular scales. Divalent and trivalent enzymatic cross-links form during the development of collagen fibrils through the enzymatic activity of lysyl oxidase (LOX). By establishing connections between telopeptidyl and triple-helical domains of adjacent molecules within collagen fibrils, these cross-links stiffen the fibrils by resisting intermolecular sliding. Ultimately, greater enzymatic cross-linking leads to less compliant and stronger tendon as a result of stiffer fibrils. In contrast, nonenzymatic cross-links such as glucosepane and pentosidine are not produced during development but slowly accumulate through glycation of collagen. Therefore, these cross-links are only expected to be present in significant quantities in advanced age, where there has been sufficient time for glycation to occur, and in diabetes, where the presence of more free sugar in the extracellular matrix increases the rate of glycation. Unlike enzymatic cross-links, current evidence suggests that nonenzymatic cross-links are at least partially isolated to the surface of collagen fibers. As a result, glycation has been proposed to primarily impact tendon mechanics by altering molecular interactions at the fiber interface, thereby diminishing sliding between fibers. Thus, increased nonenzymatic cross-linking decreases microscale strain attenuation and the viscous response of tendon. In conclusion, enzymatic and nonenzymatic collagen cross-links have demonstrable and distinct effects on the mechanical properties of tendon across different length scales.
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Affiliation(s)
- Jeremy D Eekhoff
- a Department of Biomedical Engineering , Washington University in St. Louis , St. Louis , USA
| | - Fei Fang
- b Department of Orthopedic Surgery , Columbia University , New York , USA
| | - Spencer P Lake
- a Department of Biomedical Engineering , Washington University in St. Louis , St. Louis , USA.,c Department of Mechanical Engineering and Materials Science , Washington University in St. Louis , St. Louis , USA.,d Department of Orthopaedic Surgery , Washington University in St. Louis , St. Louis , USA
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7
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Fang F, Lake SP. Experimental evaluation of multiscale tendon mechanics. J Orthop Res 2017; 35:1353-1365. [PMID: 27878999 DOI: 10.1002/jor.23488] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 11/16/2016] [Indexed: 02/04/2023]
Abstract
Tendon's primary function is a mechanical link between muscle and bone. The hierarchical structure of tendon and specific compositional constituents are believed to be critical for proper mechanical function. With increased appreciation for tendon importance and the development of various technological advances, this review paper summarizes recent experimental approaches that have been used to study multiscale tendon mechanics, includes an overview of studies that have evaluated the role of specific tissue constituents, and also proposes challenges/opportunities facing tendon study. Tendon has been demonstrated to have specific structural characteristics (e.g., multi-level hierarchy, crimp pattern, helix) and complex mechanical properties (e.g., non-linearity, anisotropy, viscoelasticity). Physical mechanisms including uncrimping, fiber sliding, and collagen reorganization have been shown to govern tendon mechanical responses under both static and dynamic loading. Several tendon constituents with relatively small quantities have been suggested to play a role in its mechanics, although some results are conflicting. Further research should be performed to understand the interplay and communication of tendon mechanical properties across levels of the hierarchical structure, and further show how each of these components contribute to tendon mechanics. The studies summarized and discussed in this review have helped elucidate important aspects of multiscale tendon mechanics, which is a prerequisite for analyzing stress/strain transfer between multiple scales and identifying key principles of mechanotransduction. This information could further facilitate interpreting the functional diversity of tendons from different species, different locations, and even different developmental stages, and then better understand and identify fundamental concepts related to tendon degeneration, disease, and healing. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1353-1365, 2017.
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Affiliation(s)
- Fei Fang
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, 1 Brookings Drive, Campus Box 1185, St. Louis, Missouri, 63130
| | - Spencer P Lake
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, 1 Brookings Drive, Campus Box 1185, St. Louis, Missouri, 63130.,Department of Biomedical Engineering, Washington University in St. Louis, 1 Brookings Drive, Campus Box 1185, St. Louis, Missouri, 63130.,Department of Orthopaedic Surgery, Washington University in St. Louis, 1 Brookings Drive, Campus Box 1185, St. Louis, Missouri, 63130
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8
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Pearson SJ, Hussain SR. Region-specific tendon properties and patellar tendinopathy: a wider understanding. Sports Med 2015; 44:1101-12. [PMID: 24838651 DOI: 10.1007/s40279-014-0201-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Patellar tendinopathy is a common painful musculoskeletal disorder with a very high prevalence in the athletic population that can severely limit or even end an athletic career. To date, the underlying pathophysiology leading to the condition remains poorly understood, although reports suggesting that patellar tendinopathy most frequently concerns the proximal posterior region of the tendon has prompted some researchers to examine region-specific tendon properties for a better understanding of the etiology and potential risk factors associated with the condition. However, to date, research concerning the in vivo region-specific tendon properties in relation to patellar tendinopathy is very scarce, perhaps due to the lack of validated techniques that can determine such properties in vivo. In recent years, a technique has been developed involving an automated tendon-tracking program that appears to be very useful in the determination of region-specific tendon properties in vivo. In terms of regional variations in tendon properties, previous research has demonstrated differences in structural, mechanical, and biochemical properties between the discrete regions of the patellar tendon, but the extent to which these regional variations contribute to patellar tendinopathy remains elusive. In addition, with respect to treatment strategies for patellar tendinopathy, previous research has utilized a wide range of interventions, but the use of eccentric exercise (EE) and/or heavy-slow resistance (HSR) training appear to be most promising. However, the optimal program design variables of EE and HSR training that induce the most favorable effects are yet to be determined. This review article provides a detailed discussion of all of the above to allow a better understanding of the etiology and potential risk factors associated with the condition as well as the most effective treatment strategies. First, a comprehensive literature review is provided with respect to region-specific structural, mechanical, and biochemical properties, in association with patellar tendinopathy. Second, the automated tendon-tracking methodology is outlined to assist future researchers in the determination of region-specific tendon properties. Finally, potential treatment strategies are discussed, particularly with regards to the use of EE and HSR training for the management of patellar tendinopathy.
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Affiliation(s)
- Stephen John Pearson
- Centre for Health, Sport and Rehabilitation Sciences Research, University of Salford, Manchester, M6 6PU, UK,
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Exercise and Regulation of Bone and Collagen Tissue Biology. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 135:259-91. [DOI: 10.1016/bs.pmbts.2015.07.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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10
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Svensson RB, Couppé C, Magnusson SP. Mechanical Properties of the Aging Tendon. ENGINEERING MATERIALS AND PROCESSES 2015. [DOI: 10.1007/978-3-319-03970-1_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Hanada M, Takahashi M, Suzuki D, Abe M, Matsuyama Y. A biochemical study of the distribution of collagen and its crosslinks in knee ligaments and the patellar tendon. Connect Tissue Res 2014; 55:378-83. [PMID: 25140988 DOI: 10.3109/03008207.2014.957283] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE The purpose of this study was to investigate biochemical differences in collagen crosslinks from different locations within the ligaments and a tendon of the human knee. MATERIALS AND METHODS The anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), lateral collateral ligament (LCL), and patellar tendon (PT) were obtained from 24 cadavers (13 men and 11 women) whose average age at the time of death was 84.8 years. Ligaments and PT samples were obtained from the femoral and tibial insertions and the midsubstance. Hydroxyproline (Hyp) and collagen crosslinks, including pyridinoline (Pyr) and pentosidine (Pen), were compared among the different sites. RESULTS The midsubstance Hyp concentration was greater than at the femoral and tibial insertions in the ACL (p = 0.00124 and 0.000255, respectively) and PCL (p = 0.00036 and 0.042, respectively). The Pyr:collagen ratio did not differ among sites in any of the ligaments or PT. The Pen:collagen ratio at the midsubstance was greater than at the femoral and tibial insertions in the ACL (p = 0.00022 and 0.00025, respectively) and LCL (p = 0.000081 and 0.000021, respectively) and was greater at the femoral insertion in the MCL (p = 0.00010). CONCLUSIONS The mature collagen crosslink Pyr was not different in distribution in knee ligaments and the PT. Pen increased at the midsubstance ligaments and the PT. As increased Pen may represent ligament degeneration, this may indicate that degeneration may progress more rapidly at the midsubstance than at the insertion sites of a ligament.
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Affiliation(s)
- Mitsuru Hanada
- Department of Orthopaedic Surgery, Hamamatsu University School of Medicine , Hamamatsu, Shizuoka , Japan and
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12
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Couppé C, Svensson RB, Grosset JF, Kovanen V, Nielsen RH, Olsen MR, Larsen JO, Praet SFE, Skovgaard D, Hansen M, Aagaard P, Kjaer M, Magnusson SP. Life-long endurance running is associated with reduced glycation and mechanical stress in connective tissue. AGE (DORDRECHT, NETHERLANDS) 2014; 36:9665. [PMID: 24997017 PMCID: PMC4150896 DOI: 10.1007/s11357-014-9665-9] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 06/18/2014] [Indexed: 05/07/2023]
Abstract
Life-long regular endurance exercise is known to counteract the deterioration of cardiovascular and metabolic function and overall mortality. Yet it remains unknown if life-long regular endurance exercise can influence the connective tissue accumulation of advanced glycation endproducts (AGEs) that is associated with aging and lifestyle-related diseases. We therefore examined two groups of healthy elderly men: 15 master athletes (64 ± 4 years) who had been engaged in life-long endurance running and 12 old untrained (66 ± 4 years) together with two groups of healthy young men; ten young athletes matched for running distance (26 ± 4 years), and 12 young untrained (24 ± 3 years). AGE cross-links (pentosidine) of the patellar tendon were measured biochemically, and in the skin, it was assessed by a fluorometric method. In addition, we determined mechanical properties and microstructure of the patellar tendon. Life-long regular endurance runners (master athletes) had a 21 % lower AGE cross-link density compared to old untrained. Furthermore, both master athletes and young athletes displayed a thicker patellar tendon. These cross-sectional data suggest that life-long regular endurance running can partly counteract the aging process in connective tissue by reducing age-related accumulation of AGEs. This may not only benefit skin and tendon but also other long-lived protein tissues in the body. Furthermore, it appears that endurance running yields tendon tissue hypertrophy that may serve to lower the stress on the tendon and thereby reduce the risk of injury.
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Affiliation(s)
- Christian Couppé
- Institute of Sports Medicine, Department of Orthopaedic Surgery M, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Bldg. 8, Bispebjerg Bakke 23, DK-2400, Copenhagen, NV, Denmark,
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"Ligamentization" in hamstring tendon grafts after anterior cruciate ligament reconstruction: a systematic review of the literature and a glimpse into the future. Arthroscopy 2013; 29:1712-21. [PMID: 23859954 DOI: 10.1016/j.arthro.2013.05.009] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 04/26/2013] [Accepted: 05/06/2013] [Indexed: 02/02/2023]
Abstract
PURPOSE The aims of this study were to provide a systematic review of the literature on "ligamentization" in hamstring tendon (HT) grafts after anterior cruciate ligament (ACL) reconstruction and analyze the postoperative remodeling process in human patients and animal models. METHODS We performed a search in the Medline, PubMed, Embase and The Cochrane Library databases, followed by a manual search of reference lists to identify relevant articles. Only studies that investigated the ligamentization of hamstring grafts by histologic examination and comprehensively reported on the remodeling process were deemed eligible for review. RESULTS A total of 4 studies were determined appropriate for systematic review: 2 of the included studies investigated human ACL grafts and 2 were performed in animal models. The studies included the examination of 79 human hamstring graft biopsy specimens and grafts of 27 skeletally mature sheep. To verify the remodeling process, authors reported on various aspects of cellularity, vascularity, and collagen organization. None of the included studies reached a level of evidence higher than 3. CONCLUSIONS A postoperative ligamentization process can be found in HT grafts after ACL reconstruction and shows a typical progression through 3 distinguishable remodeling phases in humans and in animal models, whereas the progression and intensity of remodeling is distinctly increased in animals. CLINICAL RELEVANCE Because postoperative remodeling influences biomechanical properties of hamstring grafts, a better understanding of this process and its timing could lead to substantial improvements in postoperative care strategies and indirectly to the optimization of surgical techniques.
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Hansen P, Kovanen V, Hölmich P, Krogsgaard M, Hansson P, Dahl M, Hald M, Aagaard P, Kjaer M, Magnusson SP. Micromechanical properties and collagen composition of ruptured human achilles tendon. Am J Sports Med 2013; 41:437-43. [PMID: 23263296 DOI: 10.1177/0363546512470617] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND The Achilles tendon is one of the strongest tendons in the human body, and yet it frequently ruptures, which is a substantial clinical problem. However, the cause of ruptures remains elusive. HYPOTHESIS Ruptured human Achilles tendon displays inferior biomechanical properties and altered collagen composition compared with noninjured tendon. STUDY DESIGN Controlled laboratory study. METHODS Biopsy specimens were obtained at the rupture site and the noninjured part of the tendon (internal controls) in 17 patients with acute Achilles tendon rupture. Age- and weight-matched human cadaveric Achilles tendons (external controls) were also obtained. Tendon samples were tested micromechanically and biochemically. RESULTS The mean Young modulus was lower (P < .01) in ruptured (256.7 ± 100.8 MPa) and internal control tendon (262.4 ± 111.5 MPa) compared with external control tendon (512.9 ± 209.6 MPa; P < .01), whereas failure strength did not display similar differences (P = .06-.16). Collagen content, lysyl pyridinoline (LP), hydroxylysyl pyridinoline (HP), and pentosidine (PENT) did not display regional differences between ruptured and noninjured tendon. However, collagen content was less in ruptured (0.457 ± 0.093 mg/mg) and noninjured tendon (0.476 ± 0.072 mg/mg) compared with external control tendon (0.585 ± 0.044 mg/mg, P < .001). Pentosidine was similar in all tendon samples and was positively related to age in all samples (r2 = 0.44-0.72, P < .05). Collagen content was positively related to failure stress but only in ruptured samples (r2 = 0.36; P < .05). HP, LP, and PENT content were unrelated to failure stress and Young modulus in ruptured, noninjured, and cadaveric tendon. CONCLUSION These data imply that there may be a mechanical weakening of the tendon and that a reduced collagen content may be related to the pathophysiological characteristics of Achilles tendon rupture. CLINICAL RELEVANCE Earlier studies have demonstrated that specific training regimens to treat tendon injury can improve tendon composition and mechanical properties. This study supports the notion that treatment measures should aim to increase tendon collagen content and improve micromechanical quality of the tendon matrix.
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Affiliation(s)
- Philip Hansen
- Institute of Sports Medicine Copenhagen, Bispebjerg Bakke 23, Building 8, 1st Floor, DK-2400 Copenhagen, Denmark
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15
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Hansen P, Haraldsson BT, Aagaard P, Kovanen V, Avery NC, Qvortrup K, Larsen JO, Krogsgaard M, Kjaer M, Peter Magnusson S. Lower strength of the human posterior patellar tendon seems unrelated to mature collagen cross-linking and fibril morphology. J Appl Physiol (1985) 2010; 108:47-52. [DOI: 10.1152/japplphysiol.00944.2009] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human patellar tendon is frequently affected by tendinopathy, but the etiology of the condition is not established, although differential loading of the anterior and posterior tendon may be associated with the condition. We hypothesized that changes in fibril morphology and collagen cross-linking would parallel differences in material strength between the anterior and posterior tendon. Tendon fascicles were obtained from elective ACL surgery patients and tested micromechanically. Transmission electron microscopy was used to assess fibril morphology, and collagen cross-linking was determined by HPLC and calorimetry. Anterior fascicles were markedly stronger (peak stress: 54.3 ± 21.2 vs. 39.7 ± 21.3 MPa; P < 0.05) and stiffer (624 ± 232 vs. 362 ± 170 MPa; P < 0.01) than posterior fascicles. Notably, mature pyridinium type cross-links were less abundant in anterior fascicles (hydroxylysylpyridinoline: 0.859 ± 0.197 vs. 1.416 ± 0.250 mol/mol, P = 0.001; lysylpyridinoline: 0.023 ± 0.006 vs. 0.035 ± 0.006 mol/mol, P < 0.01), whereas pentosidine and pyrrole concentrations showed no regional differences. Fibril diameters tended to be larger in anterior fascicles (7.819 ± 2.168 vs. 4.897 ± 1.434 nm2; P = 0.10). Material properties did not appear closely related to cross-linking or fibril morphology. These findings suggest region-specific differences in mechanical, structural, and biochemical properties of the human patellar tendon.
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Affiliation(s)
- Philip Hansen
- Institute of Sports Medicine Copenhagen, Bispebjerg Hospital & Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bjarki Thor Haraldsson
- Institute of Sports Medicine Copenhagen, Bispebjerg Hospital & Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Per Aagaard
- Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Vuokko Kovanen
- Department of Health Sciences, Biochemistry Laboratory, University of Jyväskylä, Jyväskylä, Finland
| | - Nicholas C. Avery
- Department of Clinical Veterinary Science, Matrix Biology Research Group, University of Bristol, Langford, North Somerset, United Kingdom
| | - Klaus Qvortrup
- Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Jytte Overgaard Larsen
- Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Michael Krogsgaard
- Department of Orthopedic Surgery, Bispebjerg Hospital, Copenhagen, Denmark
| | - Michael Kjaer
- Institute of Sports Medicine Copenhagen, Bispebjerg Hospital & Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - S. Peter Magnusson
- Institute of Sports Medicine Copenhagen, Bispebjerg Hospital & Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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16
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Couppé C, Hansen P, Kongsgaard M, Kovanen V, Suetta C, Aagaard P, Kjaer M, Magnusson SP. Mechanical properties and collagen cross-linking of the patellar tendon in old and young men. J Appl Physiol (1985) 2009; 107:880-6. [PMID: 19556458 DOI: 10.1152/japplphysiol.00291.2009] [Citation(s) in RCA: 183] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Age-related loss in muscle mass and strength impairs daily life function in the elderly. However, it remains unknown whether tendon properties also deteriorate with age. Cross-linking of collagen molecules provides structural integrity to the tendon fibrils and has been shown to change with age in animals but has never been examined in humans in vivo. In this study, we examined the mechanical properties and pyridinoline and pentosidine cross-link and collagen concentrations of the patellar tendon in vivo in old (OM) and young men (YM). Seven OM (67 +/- 3 years, 86 +/- 10 kg) and 10 YM (27 +/- 2 years, 81 +/- 8 kg) with a similar physical activity level (OM 5 +/- 6 h/wk, YM 5 +/- 2 h/wk) were examined. MRI was used to assess whole tendon dimensions. Tendon mechanical properties were assessed with the use of simultaneous force and ultrasonographic measurements during ramped isometric contractions. Percutaneous tendon biopsies were taken and analyzed for hydroxylysyl pyridinoline (HP), lysyl pyridinoline (LP), pentosidine, and collagen concentrations. We found no significant differences in the dimensions or mechanical properties of the tendon between OM and YM. Collagen concentrations were lower in OM than in YM (0.49 +/- 0.27 vs. 0.73 +/- 0.14 mg/mg dry wt; P < 0.05). HP concentrations were higher in OM than in YM (898 +/- 172 vs. 645 +/- 183 mmol/mol; P < 0.05). LP concentrations were higher in OM than in YM (49 +/- 38 vs. 16 +/- 8 mmol/mol; P < 0.01), and pentosidine concentrations were higher in OM than in YM (73 +/- 13 vs. 11 +/- 2 mmol/mol; P < 0.01). These cross-sectional data raise the possibility that age may not appreciably influence the dimensions or mechanical properties of the human patellar tendon in vivo. Collagen concentration was reduced, whereas both enzymatic and nonenzymatic cross-linking of concentration was elevated in OM vs. in YM, which may be a mechanism to maintain the mechanical properties of tendon with aging.
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Affiliation(s)
- C Couppé
- Institute of Sports Medicine, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, 2400 Copenhagen NV, Denmark
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Lemoine JK, Lee JD, Trappe TA. Impact of sex and chronic resistance training on human patellar tendon dry mass, collagen content, and collagen cross-linking. Am J Physiol Regul Integr Comp Physiol 2008; 296:R119-24. [PMID: 18945950 DOI: 10.1152/ajpregu.90607.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Collagen content and cross-linking are believed to be major determinants of tendon structural integrity and function. Sex and chronic resistance training have been shown to alter tendon function and may also alter the key structural features of tendon. Patellar tendon biopsies were taken from untrained men [n = 8, 1 repetition maximum (RM) = 53 +/- 3 kg], untrained women (n = 8, 1 RM = 29 +/- 2 kg), and resistance-trained (10 +/- 1 yr of training) men (n = 8, 1 RM = 71 +/- 6 kg). Biopsies were analyzed for dry mass, collagen content, and collagen cross-linking (hydroxylysylpyridinoline). We hypothesized that these elements of tendon structure would be lower in women than men, whereas chronic resistance training would increase these parameters in men. Tendon dry mass was significantly lower in women than men (343 +/- 5 vs. 376 +/- 8 microg dry mass/mg tendon wet wt, P < 0.01) and was not influenced by chronic resistance training (P > 0.05). The lower tendon dry mass in women tended to reduce (P = 0.08) collagen content per tendon wet weight. Collagen content of the tendon dry mass was not influenced by sex or resistance training (P > 0.05). Similarly, cross-linking of collagen was unaltered (P > 0.05) by sex or training. Although sex alters the water content of patellar tendon tissue, any changes in tendon function with sex or chronic resistance training in men do not appear to be explained by alterations in collagen content or cross-linking of collagen within the dry mass component of the tendon.
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