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Bloom ET, Lin LM, Locke RC, Giordani A, Krassan E, Peloquin JM, Silbernagel KG, Parreno J, Santare MH, Killian ML, Elliott DM. Overload in a Rat In Vivo Model of Synergist Ablation Induces Tendon Multiscale Structural and Functional Degeneration. J Biomech Eng 2023; 145:081003. [PMID: 37184932 PMCID: PMC10782872 DOI: 10.1115/1.4062523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 05/02/2023] [Accepted: 05/04/2023] [Indexed: 05/16/2023]
Abstract
Tendon degeneration is typically described as an overuse injury with little distinction made between magnitude of load (overload) and number of cycles (overuse). Further, in vivo, animal models of tendon degeneration are mostly overuse models, where tendon damage is caused by a high number of load cycles. As a result, there is a lack of knowledge of how isolated overload leads to degeneration in tendons. A surgical model of synergist ablation (SynAb) overloads the target tendon, plantaris, by ablating its synergist tendon, Achilles. The objective of this study was to evaluate the structural and functional changes that occur following overload of plantaris tendon in a rat SynAb model. Tendon cross-sectional area (CSA) and shape changes were evaluated by longitudinal MR imaging up to 8 weeks postsurgery. Tissue-scale structural changes were evaluated by semiquantified histology and second harmonic generation microscopy. Fibril level changes were evaluated with serial block face scanning electron microscopy (SBF-SEM). Functional changes were evaluated using tension tests at the tissue and microscale using a custom testing system allowing both video and microscopy imaging. At 8 weeks, overloaded plantaris tendons exhibited degenerative changes including increases in CSA, cell density, collagen damage area fraction (DAF), and fibril diameter, and decreases in collagen alignment, modulus, and yield stress. To interpret the differences between overload and overuse in tendon, we introduce a new framework for tendon remodeling and degeneration that differentiates between the inputs of overload and overuse. In summary, isolated overload induces multiscale degenerative structural and functional changes in plantaris tendon.
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Affiliation(s)
- Ellen T Bloom
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716
| | - Lily M Lin
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716
| | - Ryan C Locke
- Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104; Translational Musculoskeletal Research Center, CMCVAMC, Philadelphia, PA 19104
| | - Alyssa Giordani
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716
| | - Erin Krassan
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716
| | - John M Peloquin
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716
| | | | - Justin Parreno
- Department of Biological Sciences, University of Delaware, Newark, DE 19716
| | - Michael H Santare
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716
| | - Megan L Killian
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI 48104
| | - Dawn M Elliott
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716
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Atta G, Tempfer H, Kaser-Eichberger A, Traweger A, Heindl LM, Schroedl F. Is the human sclera a tendon-like tissue? A structural and functional comparison. Ann Anat 2021; 240:151858. [PMID: 34798297 DOI: 10.1016/j.aanat.2021.151858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 09/22/2021] [Accepted: 11/09/2021] [Indexed: 12/17/2022]
Abstract
Collagen rich connective tissues fulfill a variety of important functions throughout the human body, most of which having to resist mechanical challenges. This review aims to compare structural and functional aspects of tendons and sclera, two tissues with distinct location and function, but with striking similarities regarding their cellular content, their extracellular matrix and their low degree of vascularization. The description of these similarities meant to provide potential novel insight for both the fields of orthopedic research and ophthalmology.
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Affiliation(s)
- Ghada Atta
- Department of Ophthalmology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Institute for Tendon and Bone Regeneration, Spinal Cord Injury and Tissue Regeneration Center Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - Herbert Tempfer
- Institute for Tendon and Bone Regeneration, Spinal Cord Injury and Tissue Regeneration Center Salzburg, Paracelsus Medical University, Salzburg, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Alexandra Kaser-Eichberger
- Center for Anatomy and Cell Biology, Institute of Anatomy and Cell Biology - Salzburg, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria
| | - Andreas Traweger
- Institute for Tendon and Bone Regeneration, Spinal Cord Injury and Tissue Regeneration Center Salzburg, Paracelsus Medical University, Salzburg, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Ludwig M Heindl
- Department of Ophthalmology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Center for Integrated Oncology (CIO) Aachen - Bonn - Cologne - Düsseldorf, Cologne, Germany
| | - Falk Schroedl
- Center for Anatomy and Cell Biology, Institute of Anatomy and Cell Biology - Salzburg, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria.
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Importance of shear-wave elastography in prediction of Achilles tendon rupture. INTERNATIONAL ORTHOPAEDICS 2020; 45:1043-1047. [PMID: 32613301 DOI: 10.1007/s00264-020-04670-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 06/17/2020] [Indexed: 10/23/2022]
Abstract
PURPOSE It was demonstrated that about 6% of patients with a ruptured Achilles tendon experience the rupture of contralateral tendon in the future; the aim of this study was to estimate the risk for rupture of contralateral tendon in patients who underwent surgical reconstruction of ruptured Achilles tendon by using subjective questionnaires and shear-wave elastography. METHODS Twenty-four patients who underwent surgical repair of the ruptured Achilles tendon and twelve age-matched healthy controls were examined with ultrasound SWE. Functional outcomes were assessed with American Orthopedic Foot and Ankle Society (AOFAS) scoring system and subjective rating system which we introduced and validated. RESULTS The elasticity of injured tendon was markedly decreased (by 42%) compared to the contralateral tendon of the patient, as expected. Both AOFAS score and our novel subjective assessment scale positively correlate with ultrasound SWE values in ruptured Achilles tendons. The elasticity of contralateral Achilles tendons in patients was 23% lower than among healthy individuals. CONCLUSION Irrespective of the lack of difference in the subjective feeling assessed by AOFAS, the contralateral tendon in the patients with reconstructed Achilles tendon has significantly lower stiffness than healthy individuals. Therefore, contralateral tendons in patients who suffered from rupture are more prone to future ruptures.
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Lim WL, Liau LL, Ng MH, Chowdhury SR, Law JX. Current Progress in Tendon and Ligament Tissue Engineering. Tissue Eng Regen Med 2019; 16:549-571. [PMID: 31824819 PMCID: PMC6879704 DOI: 10.1007/s13770-019-00196-w] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 05/07/2019] [Accepted: 05/22/2019] [Indexed: 02/08/2023] Open
Abstract
Background Tendon and ligament injuries accounted for 30% of all musculoskeletal consultations with 4 million new incidences worldwide each year and thus imposed a significant burden to the society and the economy. Damaged tendon and ligament can severely affect the normal body movement and might lead to many complications if not treated promptly and adequately. Current conventional treatment through surgical repair and tissue graft are ineffective with a high rate of recurrence. Methods In this review, we first discussed the anatomy, physiology and pathophysiology of tendon and ligament injuries and its current treatment. Secondly, we explored the current role of tendon and ligament tissue engineering, describing its recent advances. After that, we also described stem cell and cell secreted product approaches in tendon and ligament injuries. Lastly, we examined the role of the bioreactor and mechanical loading in in vitro maturation of engineered tendon and ligament. Results Tissue engineering offers various alternative ways of treatment from biological tissue constructs to stem cell therapy and cell secreted products. Bioreactor with mechanical stimulation is instrumental in preparing mature engineered tendon and ligament substitutes in vitro. Conclusions Tissue engineering showed great promise in replacing the damaged tendon and ligament. However, more study is needed to develop ideal engineered tendon and ligament.
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Affiliation(s)
- Wei Lee Lim
- Tissue Engineering Centre, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, 56000 Kuala Lumpur, Malaysia
| | - Ling Ling Liau
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, JalanYaacob Latif, 56000 Kuala Lumpur, Malaysia
| | - Min Hwei Ng
- Tissue Engineering Centre, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, 56000 Kuala Lumpur, Malaysia
| | - Shiplu Roy Chowdhury
- Tissue Engineering Centre, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, 56000 Kuala Lumpur, Malaysia
| | - Jia Xian Law
- Tissue Engineering Centre, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, 56000 Kuala Lumpur, Malaysia
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Zitnay JL, Weiss JA. Load transfer, damage, and failure in ligaments and tendons. J Orthop Res 2018; 36:3093-3104. [PMID: 30175857 PMCID: PMC6454883 DOI: 10.1002/jor.24134] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 08/14/2018] [Indexed: 02/04/2023]
Abstract
The function of ligaments and tendons is to support and transmit loads applied to the musculoskeletal system. These tissues are often able to perform their function for many decades; however, connective tissue disease and injury can compromise ligament and tendon integrity. A range of protein and non-protein constituents, combined in a complex structural hierarchy from the collagen molecule to the tissue and covering nanometer to centimeter length scales, govern tissue function, and impart characteristic non-linear material behavior. This review summarizes the structure of ligaments and tendons, the roles of their constituent components for load transfer across the hierarchy of structure, and the current understanding of how damage occurs in these tissues. Disease and injury can alter the constituent make-up and structural organization of ligaments and tendons, affecting tissue function, while also providing insight to the role and interactions of individual constituents. The studies and techniques presented here have helped to understand the relationship between tissue constituents and the physical mechanisms (e.g., stretching, sliding) that govern material behavior at and between length scales. In recent years, new techniques have been developed to probe ever smaller length scales and may help to elucidate mechanisms of load transfer and damage and the molecular constituents involved in the in the earliest stages of ligament and tendon damage. A detailed understanding of load transfer and damage from the molecular to the tissue level may elucidate targets for the treatment of connective tissue diseases and inform practice to prevent and rehabilitate ligament and tendon injuries. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3093-3104, 2018.
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Affiliation(s)
- Jared L. Zitnay
- Department of Bioengineering, and Scientific Computing and Imaging Institute University of Utah
| | - Jeffrey A. Weiss
- Department of Bioengineering, and Scientific Computing and Imaging Institute University of Utah,Department of Orthopaedics, University of Utah
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Schneider M, Angele P, Järvinen TA, Docheva D. Rescue plan for Achilles: Therapeutics steering the fate and functions of stem cells in tendon wound healing. Adv Drug Deliv Rev 2018; 129:352-375. [PMID: 29278683 DOI: 10.1016/j.addr.2017.12.016] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 12/01/2017] [Accepted: 12/22/2017] [Indexed: 02/07/2023]
Abstract
Due to the increasing age of our society and a rise in engagement of young people in extreme and/or competitive sports, both tendinopathies and tendon ruptures present a clinical and financial challenge. Tendon has limited natural healing capacity and often responds poorly to treatments, hence it requires prolonged rehabilitation in most cases. Till today, none of the therapeutic options has provided successful long-term solutions, meaning that repaired tendons do not recover their complete strength and functionality. Our understanding of tendon biology and healing increases only slowly and the development of new treatment options is insufficient. In this review, following discussion on tendon structure, healing and the clinical relevance of tendon injury, we aim to elucidate the role of stem cells in tendon healing and discuss new possibilities to enhance stem cell treatment of injured tendon. To date, studies mainly apply stem cells, often in combination with scaffolds or growth factors, to surgically created tendon defects. Deeper understanding of how stem cells and vasculature in the healing tendon react to growth factors, common drugs used to treat injured tendons and promising cellular boosters could help to develop new and more efficient ways to manage tendon injuries.
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Bordvik DH, Haslerud S, Naterstad IF, Lopes-Martins RAB, Leal Junior ECP, Bjordal JM, Joensen J. Penetration Time Profiles for Two Class 3B Lasers inIn SituHuman Achilles at Rest and Stretched. Photomed Laser Surg 2017; 35:546-554. [DOI: 10.1089/pho.2016.4257] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Affiliation(s)
- Daniel Huseby Bordvik
- NorPhyPain Research Group, Faculty of Health and Social Sciences, Centre for Evidence Based Practice, Bergen University College, Bergen, Norway
- Physiotherapy Research Group, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
- Haugesund Rheumatological Hospital, Rehabilitation West A/S, Haugesund, Norway
| | - Sturla Haslerud
- NorPhyPain Research Group, Faculty of Health and Social Sciences, Centre for Evidence Based Practice, Bergen University College, Bergen, Norway
- Physiotherapy Research Group, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
| | - Ingvill Fjell Naterstad
- NorPhyPain Research Group, Faculty of Health and Social Sciences, Centre for Evidence Based Practice, Bergen University College, Bergen, Norway
- Physiotherapy Research Group, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
| | - Rodrigo Alvaro Brandão Lopes-Martins
- Nucleous of Technological Research—NPT, Post-Graduate Program in Biomedical Engineering, University of Mogi das Cruzes (UMC), Mogi das Cruzes, São Paulo, Brazil
| | | | - Jan Magnus Bjordal
- NorPhyPain Research Group, Faculty of Health and Social Sciences, Centre for Evidence Based Practice, Bergen University College, Bergen, Norway
- Physiotherapy Research Group, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
- Department of Occupational Therapy, Physiotherapy and Radiography, Bergen University College, Bergen, Norway
| | - Jon Joensen
- NorPhyPain Research Group, Faculty of Health and Social Sciences, Centre for Evidence Based Practice, Bergen University College, Bergen, Norway
- Physiotherapy Research Group, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
- Department of Occupational Therapy, Physiotherapy and Radiography, Bergen University College, Bergen, Norway
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8
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Pearson SJ, Engel AJ, Bashford GR. Changes in tendon spatial frequency parameters with loading. J Biomech 2017; 57:136-140. [PMID: 28410739 DOI: 10.1016/j.jbiomech.2017.03.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/20/2017] [Accepted: 03/24/2017] [Indexed: 10/19/2022]
Abstract
To examine and compare the loading related changes in micro-morphology of the patellar tendon. Fifteen healthy young males (age 19±3yrs, body mass 83±5kg) were utilised in a within subjects matched pairs design. B mode ultrasound images were taken in the sagittal plane of the patellar tendon at rest with the knee at 90° flexion. Repeat images were taken whilst the subjects were carrying out maximal voluntary isometric contractions. Spatial frequency parameters related to the tendon morphology were determined within regions of interest (ROI) from the B mode images at rest and during isometric contractions. A number of spatial parameters were observed to be significantly different between resting and contracted images (Peak spatial frequency radius (PSFR), axis ratio, spatial Q-factor, PSFR amplitude ratio, and the sum). These spatial frequency parameters were indicative of acute alterations in the tendon micro-morphology with loading. Acute loading modifies the micro-morphology of the tendon, as observed via spatial frequency analysis. Further research is warranted to explore its utility with regard to different loading induced micro-morphological alterations, as these could give valuable insight not only to aid strengthening of this tissue but also optimization of recovery from injury and treatment of conditions such as tendinopathies.
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Affiliation(s)
- Stephen J Pearson
- Centre of Health, Sport and Rehabilitation Sciences Research, University of Salford, Manchester M6 6PU, United Kingdom.
| | - Aaron J Engel
- Dept. of Biological Systems Engineering, University of Nebraska-Lincoln, USA
| | - Gregory R Bashford
- Dept. of Biological Systems Engineering, University of Nebraska-Lincoln, USA
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Suzuki D, Otsubo H, Watanabe T, Kamiya T, Nagoya S, Yamashita T, Shino K. Ultrastructure of the three anterior cruciate ligament bundles. Clin Anat 2015; 28:910-6. [DOI: 10.1002/ca.22586] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 06/05/2015] [Accepted: 06/06/2015] [Indexed: 12/17/2022]
Affiliation(s)
- Daisuke Suzuki
- Department of Musculoskeletal Biomechanics and Surgical Development; Sapporo Medical University; Sapporo Japan
| | - Hidenori Otsubo
- Department of Orthopaedic Surgery; Sapporo Medical University School of Medicine; Sapporo Japan
| | - Takafumi Watanabe
- Faculty of Agriculture; Shinshu University, Minami-minowa, Kami-ina; Nagano Japan
| | - Tomoaki Kamiya
- Department of Orthopaedic Surgery; Sapporo Medical University School of Medicine; Sapporo Japan
| | - Satoshi Nagoya
- Department of Musculoskeletal Biomechanics and Surgical Development; Sapporo Medical University; Sapporo Japan
| | - Toshihiko Yamashita
- Department of Orthopaedic Surgery; Sapporo Medical University School of Medicine; Sapporo Japan
| | - Konsei Shino
- Sports Orthopaedic Center, Yukioka Hospital; Osaka Japan
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10
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Shim VB, Fernandez JW, Gamage PB, Regnery C, Smith DW, Gardiner BS, Lloyd DG, Besier TF. Subject-specific finite element analysis to characterize the influence of geometry and material properties in Achilles tendon rupture. J Biomech 2014; 47:3598-604. [DOI: 10.1016/j.jbiomech.2014.10.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 10/06/2014] [Accepted: 10/06/2014] [Indexed: 11/25/2022]
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11
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Cheng CW, Solorio LD, Alsberg E. Decellularized tissue and cell-derived extracellular matrices as scaffolds for orthopaedic tissue engineering. Biotechnol Adv 2014; 32:462-84. [PMID: 24417915 PMCID: PMC3959761 DOI: 10.1016/j.biotechadv.2013.12.012] [Citation(s) in RCA: 241] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 12/27/2013] [Accepted: 12/31/2013] [Indexed: 02/07/2023]
Abstract
The reconstruction of musculoskeletal defects is a constant challenge for orthopaedic surgeons. Musculoskeletal injuries such as fractures, chondral lesions, infections and tumor debulking can often lead to large tissue voids requiring reconstruction with tissue grafts. Autografts are currently the gold standard in orthopaedic tissue reconstruction; however, there is a limit to the amount of tissue that can be harvested before compromising the donor site. Tissue engineering strategies using allogeneic or xenogeneic decellularized bone, cartilage, skeletal muscle, tendon and ligament have emerged as promising potential alternative treatment. The extracellular matrix provides a natural scaffold for cell attachment, proliferation and differentiation. Decellularization of in vitro cell-derived matrices can also enable the generation of autologous constructs from tissue specific cells or progenitor cells. Although decellularized bone tissue is widely used clinically in orthopaedic applications, the exciting potential of decellularized cartilage, skeletal muscle, tendon and ligament cell-derived matrices has only recently begun to be explored for ultimate translation to the orthopaedic clinic.
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Affiliation(s)
- Christina W Cheng
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Wickenden Building, Rm 218, Cleveland, OH, USA; Department of Orthopaedic Surgery, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH, USA.
| | - Loran D Solorio
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Wickenden Building, Rm 218, Cleveland, OH, USA.
| | - Eben Alsberg
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Wickenden Building, Rm 218, Cleveland, OH, USA; Department of Orthopaedic Surgery, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH, USA; National Center for Regenerative Medicine, Division of General Medical Sciences, Case Western Reserve University, Cleveland, OH, USA.
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12
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Kubo K, Yuki K, Ikebukuro T. Changes in bone alkaline phosphatase and procollagen type-1 C-peptide after static and dynamic exercises. RESEARCH QUARTERLY FOR EXERCISE AND SPORT 2012; 83:49-54. [PMID: 22428411 DOI: 10.1080/02701367.2012.10599824] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We investigated the effects of two types of nonweight-bearing exercise on changes in bone-specific alkaline phosphatase (BAP) and procollagen type 1 C-peptide (PIP). BAP is a specific marker of bone synthesis, whereas P1P reflects synthesis of type 1 collagen in other organs as well as bone. Eight participants performed static and dynamic unilateral knee extensions. BAP and PIP were measured before, and at 1, 2, 24, 48, and 72 hr after exercise. PIP increased at 24 hr after a static knee extension exercise, whereas BAP did not change during the experimental period. We found no changes in these markers after dynamic exercise. These results imply that type I collagen synthesis in tendons increases after static exercise.
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Affiliation(s)
- Keitaro Kubo
- Department of Life Science (Sports Sciences) University of Tokyo, Japan.
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14
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Kannus R, Jòzsa L, Renström R, Järvtoen M, Kvist M, Lento M, Oja P, Vuorl I. The effects of training, immobilization and remobilization on musculoskeletal tissue. Scand J Med Sci Sports 2007. [DOI: 10.1111/j.1600-0838.1992.tb00330.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Hosaka Y, Ueda H, Yamasaki T, Suzuki D, Matsuda N, Takehana K. Structure and component alteration of rabbit Achilles tendon in tissue culture. Biomed Res 2006; 26:279-86. [PMID: 16415509 DOI: 10.2220/biomedres.26.279] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The aim of this study was to investigate alterations of cultured tendon tissues to determine whether tissue culture is a useful method for biological analyses of the tendon. Tendon tissues for tissue culture were isolated from Achilles tendons of rabbits. The tendon segments were placed one segment per well and incubated in growth medium consisting of Dullbecco's modified Eagle's medium supplemented with 5% fetal bovine serum at 37 degrees C in a humidified atmosphere with 5% CO(2) for various periods. The alignment of collagen fibrils was preserved for 48 h, but tendon structure has disintegrated at 96 h. Alcian blue staining and gelatine zymography revealed that proteoglycan markedly diminished and that matrix metalloproteinase (MMPs) activity was upregulated sharply at 72 and 96 h. The ratio of collagen fibrils with large diameter had increased and the mean diameter and mass average diameter value had reached maximum at 48 h. The values then decreased and mean diameters at 72 and 96 h were significantly different from that at 48 h. At 96 h, the ratio of collagen fibrils with small diameters had increased and collagen fibrils with large diameters had disappeared. These findings indicate that structural alteration is possible to be induced by disintegration of collagen fibrils and disappearance of glycosaminoglycans from extracellular matrix (ECM), subsequent of upregulation of MMPs activity. Although the study period is limited, the tissue culture method is available for investigating cell-ECM interaction in tendons.
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Affiliation(s)
- Yoshinao Hosaka
- Laboratory of Veterinary Anatomy, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaida 069-8501, Japan.
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Kongsgaard M, Aagaard P, Kjaer M, Magnusson SP. Structural Achilles tendon properties in athletes subjected to different exercise modes and in Achilles tendon rupture patients. J Appl Physiol (1985) 2005; 99:1965-71. [PMID: 16081623 DOI: 10.1152/japplphysiol.00384.2005] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The prevalence of Achilles tendon (AT) injury is high in various sports, and AT rupture patients have been reported to have a 200-fold risk of sustaining a contralateral rupture. Tendon adaptation to different exercise modes is not fully understood. The present study investigated the structural properties of the AT in male elite athletes that subject their AT to different exercise modes as well as in Achilles rupture patients. Magnetic resonance imaging of the foot and leg, anthropometric measurements, and maximal isometric plantar flexion force were obtained in 6 male AT rupture patients and 25 male elite athletes (kayak/control group n = 9, volleyball n = 8 and endurance running n = 8). AT cross-sectional area (CSA) was normalized to body mass. Runners had a larger normalized AT CSA along the entire length of the tendon compared with the control group (P < 0.05). The volleyball subjects had a larger normalized CSA compared with the control group (P < 0.05) in the area of thinnest tendon CSA. No structural differences of the AT were found in the rupture subjects compared with the control group. Rupture subjects did not subject their AT to greater force or stress during a maximal voluntary isometric plantar flexion than the other groups. The CSA of the triceps surae musculature was the strongest predictor of AT CSA (r(s) = 0.569, P < 0.001). This study is the first to show larger CSA in tendons that are subjected to intermittent high loads. AT rupture patients did not display differences in structural or loading properties of the tendons.
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Affiliation(s)
- M Kongsgaard
- Institute of Sports Medicine, Bispebjerg Hospital, 2400 Copenhagen, Denmark.
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17
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Abstract
Tendons are able to respond to mechanical forces by altering their structure, composition, and mechanical properties--a process called tissue mechanical adaptation. The fact that mechanical adaptation is effected by cells in tendons is clearly understood; however, how cells sense mechanical forces and convert them into biochemical signals that ultimately lead to tendon adaptive physiological or pathological changes is not well understood. Mechanobiology is an interdisciplinary study that can enhance our understanding of mechanotransduction mechanisms at the tissue, cellular, and molecular levels. The purpose of this article is to provide an overview of tendon mechanobiology. The discussion begins with the mechanical forces acting on tendons in vivo, tendon structure and composition, and its mechanical properties. Then the tendon's response to exercise, disuse, and overuse are presented, followed by a discussion of tendon healing and the role of mechanical loading and fibroblast contraction in tissue healing. Next, mechanobiological responses of tendon fibroblasts to repetitive mechanical loading conditions are presented, and major cellular mechanotransduction mechanisms are briefly reviewed. Finally, future research directions in tendon mechanobiology research are discussed.
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Affiliation(s)
- James H-C Wang
- MechanoBiology Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh, 210 Lothrop St., BST, E1647, Pittsburgh, PA 15213, USA.
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Yang C, Zhao C, Amadio PC, Tanaka T, Zhao KD, An KN. Total and intrasynovial work of flexion of human cadaver flexor digitorum profundus tendons after modified Kessler and MGH repair techniques. J Hand Surg Am 2005; 30:466-70. [PMID: 15925153 DOI: 10.1016/j.jhsa.2004.10.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Revised: 10/22/2004] [Accepted: 10/25/2004] [Indexed: 02/02/2023]
Abstract
PURPOSE The purpose of this study was to compare directly the total work of flexion (TWOF) and the intrasynovial work of flexion (IWOF) of human flexor digitorum profundus tendons and to analyze the ratio of the IWOF to the TWOF of human flexor digitorum profundus tendons. These factors may be important clinically in understanding the role of different methods of postoperative tendon rehabilitation for different types of tendon repairs, especially at the early stage after tendon repair. METHODS Two different tendon repairs, the modified Kessler and the Massachusetts General Hospital, were used in 18 digits from 6 freshly frozen human cadaver hands. The TWOF and the IWOF were tested by using a digit-resistance testing device. RESULTS After tendon repair the TWOF increased 11.2% and 26.9% for the modified Kessler and MGH groups, respectively. The differences in increase between the 2 groups were significant. The IWOF increased 126.8% and 308.8% for the modified Kessler and Massachusetts General Hospital groups, respectively. The IWOF accounted for 16.4% of the TWOF for the intact tendon; this percentage was 28.6% and 45.0% for the modified Kessler and Massachusetts General Hospital groups, respectively. CONCLUSIONS The IWOF accounts for 16% of the TWOF of normal human cadaver digits but it accounts for a much higher fraction after tendon repair. The ratio of the work of flexion within the synovial sheath to the TWOF varies depending on the type of repair chosen.
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Affiliation(s)
- Chao Yang
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN 55905, USA
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Järvinen TAH, Järvinen TLN, Kannus P, Józsa L, Järvinen M. Collagen fibres of the spontaneously ruptured human tendons display decreased thickness and crimp angle. J Orthop Res 2004; 22:1303-9. [PMID: 15475213 DOI: 10.1016/j.orthres.2004.04.003] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2004] [Accepted: 04/08/2004] [Indexed: 02/04/2023]
Abstract
PURPOSE To study collagen fibre thickness and crimp formation in healthy and ruptured human tendons. METHODS The thickness, crimp angle and wavelength of the collagen fibres were analyzed by interference and polarization microscopy and the samples were studied by transmission and scanning electron microscopy in four different healthy human tendons (Achilles, Quadriceps, Biceps brachii and Extensor pollicis longus) and in 66 spontaneously ruptured tendons. RESULTS In the normal (healthy) tendons, the diameter and crimp angle of the collagen fibres varied greatly between the four different tendons, the thickest fibres with the largest crimp angle being in the Achilles and Quadriceps tendons, whereas the Biceps brachii and Extensor pollicis longus, tendons that bear lighter strains but carry functions of high specificity, were found to have substantially smaller collagen fibres with lower crimp angle. Ruptured tendons had significantly smaller collagen fibre diameter than the normal tendons, the fibre diameter being -36% in comparison to their healthy counterparts in the Achilles tendons (P < 0.0001), -24% in the Quadriceps tendons (P < 0.0001), -37% in the Biceps brachii (P < 0.0001) and -14% in the Extensor pollicis longus (P = 0.10), respectively. Similarly, the crimp angle of the collagen fibres was also found to be lower in the ruptured tendons than in healthy, normal tendons. Further, the collagen fibres in the ruptured human tendons showed great variation in the crimp angle between the adjacent fibres and in the successive crimps of the same fibre. CONCLUSION Our results show that spontaneously ruptured tendons display focal regions with decreased collagen fibre thickness, decreased crimp angle and disrupted crimp continuity, microscopic alterations that possibly result in reduced strength of the tendons being less resistant to tensile forces, and thus, place them at increased risk of ruptures.
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Affiliation(s)
- Tero A H Järvinen
- The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.
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Forslund C. BMP treatment for improving tendon repair. Studies on rat and rabbit Achilles tendons. ACTA ORTHOPAEDICA SCANDINAVICA. SUPPLEMENTUM 2003; 74:I, 1-30. [PMID: 12640969 DOI: 10.1080/000164702760300006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Carina Forslund
- Department of Orthopedics, Lund University Hospital, LUND, Sweden
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Abstract
The aim of this study was to investigate the involvement of apoptosis (programmed cell death) in the pathogenesis of rotator cuff disorders. The edges of torn supraspinatus rotator cuff tendons were collected from patients with rotator cuff tear (n = 25). Samples of the intra-articular portion of subscapularis tendons were collected from patients without rotator cuff tear as control (n = 6). To minimize individual variance, we also collected six pairs of supraspinatus tendon and subscapularis tendon from six patients with rotator cuff tears. Apoptosis was detected by in situ DNA end labelling assay and DNA laddering assay. Immunohistochemical staining was performed to identify cells undergoing apoptosis. Control subscapularis tendon had normal morphology. Tendon from torn supraspinatus rotator cuff showed significant mucoid degeneration. Within the areas of degeneration, there were large numbers of apoptotic cells. The percentage of apoptotic cells in the degenerative rotator cuff (34%) was significantly higher than that in controls (13%) (p < 0.001). The excessive apoptosis detected in degenerative rotator cuff tissue was confirmed by DNA laddering assays. This is the first report of excessive apoptosis in degenerating rotator cuff tendon. Cells undergoing apoptosis in rotator cuff were mainly fibroblast-like cells. These finding indicate that apoptosis may play an important role in the pathogenesis of rotator cuff degeneration.
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Affiliation(s)
- Jun Yuan
- Orthopaedic Research Institute, St George Hospital Campus, 4-10 South Street, University of New, South Wales, Sydney, NSW 2217, Australia
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22
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Toczylowski HM, Balint CR, Steiner ME, Boardman M, Scheller AD. Complete rupture of the distal biceps brachii tendon in female patients: a report of 2 cases. J Shoulder Elbow Surg 2002; 11:516-8. [PMID: 12378174 DOI: 10.1067/mse.2002.126617] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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23
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van Schie HT, Bakker EM, Jonker AM, van Weeren PR. Efficacy of computerized discrimination between structure-related and non-structure-related echoes in ultrasonographic images for the quantitative evaluation of the structural integrity of superficial digital flexor tendons in horses. Am J Vet Res 2001; 62:1159-66. [PMID: 11453496 DOI: 10.2460/ajvr.2001.62.1159] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate effectiveness of computerized discrimination between structure-related and non-structure-related echoes in ultrasonographic images for quantitative evaluation of tendon structural integrity in horses. SAMPLE POPULATION 4 superficial digital flexor tendons (2 damaged tendons, 2 normal tendons). PROCEDURE Transverse ultrasonographic images that precisely matched histologic sections were obtained in fixed steps along the long axis of each tendon. Distribution, intensity, and delineation of structure-related echoes, quantitatively expressed as the correlation ratio and steadiness ratio , were compared with histologic findings in tissue that was normal or had necrosis, early granulation, late granulation, early fibrosis, or inferior repair. RESULTS In normal tendon, the even distribution of structure-related echoes with high intensity and sharp delineation yielded high correlation ratio and steadiness ratio. In areas of necrosis, collapsed endotendon septa yielded solid but blurred structure-related echoes (high correlation ration and low steadiness ratio). In early granulation tissue, complete lack of organization caused zero values for both ratios. In late granulation tissue, reorganization and swollen endotendon septa yielded poorly delineated structure-related echoes (high correlation ratio, low steadiness ratio). In early fibrosis, rearrangement of bundles resulted in normal correlation ration and slightly low steadiness ratio. In inferior repair, the almost complete lack of structural reorganization resulted in heterogeneous poorly delineated low-intensity echoes (low correlation ratio and steadiness ratio). CONCLUSIONS AND CLINICAL RELEVANCE The combination of correlation ratio and steadiness ratio accurately reflects histopathologic findings, making computerized correlation of ultrasonographic images an efficient tool for quantitative evaluation of tendon structural integrity.
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Affiliation(s)
- P Benecke
- Department of Surgery, Universitatsklinikum, University of Lübeck, Germany
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25
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KRAUSHAAR BARRYS, NIRSCHL ROBERTP. Current Concepts Review - Tendinosis of the Elbow (Tennis Elbow). Clinical Features and Findings of Histological, Immunohistochemical, and Electron Microscopy Studies*. J Bone Joint Surg Am 1999. [DOI: 10.2106/00004623-199902000-00014] [Citation(s) in RCA: 452] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
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Birch HL, Bailey AJ, Goodship AE. Macroscopic 'degeneration' of equine superficial digital flexor tendon is accompanied by a change in extracellular matrix composition. Equine Vet J 1998; 30:534-9. [PMID: 9844973 DOI: 10.1111/j.2042-3306.1998.tb04530.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Injuries to the superficial digital flexor tendon are common in horses required to gallop and jump at speed. Partial rupture of this tendon usually occurs in the central core of the midmetacarpal region and may be preceded by localised degenerative changes. Post mortem examination of apparently normal equine flexor tendons has revealed an abnormal macroscopic appearance in the central core, characterised by a reddish discolouration. We have previously shown that there is also physical damage to the collagen fibres. In the present study we tested the hypothesis that the abnormal appearance is accompanied by changes in the composition of the extracellular matrix of the tendon. Biochemical analysis of the extracellular matrix demonstrated an increase in total sulphated glycosaminoglycan content, increase in the proportion of type III collagen and decrease in collagen linked fluorescence in the central core of 'degenerated' tendons relative to tissue from the peripheral region of the same tendon. Dry matter content and total collagen content were not significantly different between tendon zones or normal and 'degenerated' tendons. These changes suggest a change in cell metabolism and matrix turnover in the central core of the tendon and are likely to contribute to a decrease in mechanical properties in this part of the tendon, predisposing to the characteristic partial rupture of the tendon.
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Affiliation(s)
- H L Birch
- Veterinary Basic Sciences, Royal Veterinary College, North Mymms, Hatfield, UK
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Stiskal M, Szolar DH, Stenzel I, Steiner E, Mesaric P, Czembirek H, Preidler KW. Magnetic resonance imaging of Achilles tendon in patients with rheumatoid arthritis. Invest Radiol 1997; 32:602-8. [PMID: 9342119 DOI: 10.1097/00004424-199710000-00004] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
RATIONALE AND OBJECTIVES The authors characterize the appearance of the Achilles tendon in patients with rheumatoid arthritis and differentiate this appearance from degenerative tendinopathy in patients with chronic pain of the heel using magnetic resonance (MR) imaging. METHODS Thirty patients with rheumatoid arthritis and 28 patients with chronic pain of the heel underwent MR imaging of the ankle and foot. Three radiologists independently assessed the MR images with respect to size, shape, and intratendinal signal characteristics of the Achilles tendon. The Achilles tendon was considered abnormal on MR imaging when intratendinous signal alterations or an anteroposterior measurement greater than 8 mm was seen. Physical examination of the Achilles tendons was accomplished in both groups. Operation confirmed the diagnosis of 13 patients in the second group with chronic pain of the heel. RESULTS The Achilles tendon of 83% of patients with rheumatoid arthritis demonstrated various intratendinous patterns (longitudinal, reticular, nodular) of intermediate signal intensity on all pulse sequences on MR imaging. Ninety percent of patients with rheumatoid tendinopathy showed no enlargement of the anteroposterior diameter of the Achilles tendon. In addition, all patients with rheumatoid arthritis had findings compatible with an inflammation of the retrocalcaneal bursa on MR imaging, whereas none of the patients with tendinopathy associated with chronic heel pain had retrocalcaneal bursitis. All patients, however, had enlargement of the anteroposterior diameter of the Achilles tendon. Seventy-nine percent showed various intratendinous lesions of intermediate signal intensity on all pulse sequences. Twenty-one percent of patients had an enlargement of the Achilles tendon without intratendinous changes. CONCLUSIONS Rheumatoid tendinopathy can be distinguished from degenerative tendinopathy in patients with chronic pain of the heel with MR imaging. Inflammation of the retrocalcaneal bursa and the absence of enlargement of the tendon combined with the presence of intratendinous signal alterations are characteristic findings of rheumatoid tendinopathy.
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Affiliation(s)
- M Stiskal
- Department of Radiology KH Lainz-Vienna, Austria
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Kannus P, Józsa L, Natri A, Järvinen M. Effects of training, immobilization and remobilization on tendons. Scand J Med Sci Sports 1997; 7:67-71. [PMID: 9211606 DOI: 10.1111/j.1600-0838.1997.tb00121.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Since a tendon is a living tissue, it is not a surprise that tendon shows the capacity to adapt its structure and mechanical properties to the functional demands of the entire muscle-tendon unit. However, compared with muscle, the experimental knowledge of the effects of strength or endurance-type training on tendon tissue is scarce and clinical human experiments are completely lacking (1). Research should, however, be able to improve the true understanding of the biomechanical, functional, morphological and biochemical changes that occur in tendons due to training and physical activity, since understanding of the basic physiology of a tissue is the key to understanding its pathological processes (1, 2). Compared with muscle tissue, the metabolic turnover of tendon tissue is many times slower due to poorer vascularity and circulation (1, 3). The adaptive responses of tendons to training are therefore also slower than those in muscles, but they may finally be considerable if the time frame is long enough (3, 4).
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Affiliation(s)
- P Kannus
- Accident and Trauma Research Center, UKK, Institute, Tampere, Finland
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Abstract
Two-thirds of Achilles tendon injuries in competitive athletes are paratenonitis and one-fifth are insertional complaints (bursitis and insertion tendinitis). The remaining afflictions consist of pain syndromes of the myotendineal junction and tendinopathies. The majority of Achilles tendon injuries from sport occur in males, mainly because of their higher rates of participation in sport, but also with tendinopathies a gender difference is probably indicated. Athletes in running sports have a high incidence of Achilles tendon overuse injuries. About 75% of total and the majority of partial tendon ruptures are related to sports activities usually involving abrupt repetitive jumping and sprinting movements. Mechanical factors and a sedentary lifestyle play a role in the pathology of these injuries. Achilles tendon overuse injuries occur at a higher rate in older athletes than most other typical overuse injuries. Recreational athletes with a complete Achilles tendon rupture are about 15 years younger than those with other spontaneous tendon ruptures. Following surgery, about 70 to 90% of athletes have a successful comeback after Achilles tendon injury. Surgery is required in about 25% of athletes with Achilles tendon overuse injuries and the frequency of surgery increases with patient age and duration of symptoms as well as occurrence of tendinopathic changes. However, about 20% of injured athletes require a re-operation for Achilles tendon overuse injuries, and about 3 to 5% are compelled to abandon their sports career because of these injuries. Myotendineal junction pain should be treated conservatively. Partial Achilles tendon ruptures are primarily treated conservatively, although the best treatment method of chronic partial rupture seems to be surgery. Complete Achilles tendon ruptures of athletes are treated surgically, because this increases the likelihood of athletes reaching preinjury activity levels and minimises the risk of re-ruptures. Marked forefoot varus is found in athletes with Achilles tendon overuse injuries, reflecting the predisposing role of ankle joint overpronation. Athletes with the major stress in lower extremities have often a limited range of motion in the passive dorsiflexion of the ankle joint and total subtalar joint mobility, which seems to be predisposing factor for these injuries. Various predisposing transient factors are found in about one-third of athletes with Achilles tendon overuse injuries; of these, traumatic factors (mostly minor injuries) predominate. The typical histological features of chronically inflamed paratendineal tissue of the Achilles tendon are profound proliferation of loose, immature connective tissue and marked obliterative and degenerative alterations in the blood vessels. These changes cause continuing leakage of plasma proteins, which may have an important role in the pathophysiology of these injuries. The chronically inflamed paratendineal tissues of the Achilles tendon do not seem to have enough capacity to form mature connective tissue.
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Affiliation(s)
- M Kvist
- Sports Medical Research Unit, Paavo Nurmi Centre, University of Turku, Finland
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Abstract
So-called amianthoid fibres were identified in 17 of 460 tendons (3.7%) after spontaneous rupture. These tendons belonged to 10 men and 7 women with an age-range from 18 to 67 years. In 445 postmortem control tendons taken of accidentally killed previously healthy persons amianthoid fibres were not found. Ultrastructurally the tendineal amianthoid fibres differ from normal tendon collagen fibrils in many respects. Their diameter (600-1400 nm) is many times larger than that of native collagen fibrils (20-120 nm). The fibre profile is often irregular and the cross-sectioned fibres have a homogeneous granular appearance. In longitudinal sections, the amianthoid fibres are frequently disintegrated and outspread, and some of the fibres have lost their periodicity. In addition, some of the fibres are angulated and show nonparallel organization. Occasionally the amianthoid fibres are calcified.
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Affiliation(s)
- L Józsa
- Department of Morphology, National Institute of Traumatology, Budapest, Hungary
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