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Mora KE, Mlawer SJ, Loiselle AE, Buckley MR. The Micromechanical Environment of the Impinged Achilles Tendon. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2401015. [PMID: 38966889 DOI: 10.1002/smll.202401015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 06/13/2024] [Indexed: 07/06/2024]
Abstract
Although tendon predominantly experiences longitudinal tensile forces, transverse forces due to impingement from bone are implicated in both physiological and pathophysiological processes. However, prior studies have not characterized the micromechanical strain environment in the context of tendon impingement. To address this knowledge gap, mouse hindlimb explants are imaged on a multiphoton microscope, and image stacks of the same population of tendon cells are obtained in the Achilles tendon before and after dorsiflexion-induced impingement by the heel bone. Based on the acquired images, multiaxial strains are measured at the extracellular matrix (ECM), pericellular matrix (PCM), and cell scales. Impingement generated substantial transverse compression at the matrix-scale, which led to longitudinal stretching of cells, increased cell aspect ratio, and enormous volumetric compression of the PCM. These experimental results are corroborated by a finite element model, which further demonstrated that impingement produces high cell surface stresses and strains that greatly exceed those brought about by longitudinal tension. Moreover, in both experiments and simulations, impingement-generated microscale stresses and strains are highly dependent on initial cell-cell gap spacing. Identifying factors that influence the microscale strain environment generated by impingement could contribute to a more mechanistic understanding of impingement-induced tendinopathies.
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Affiliation(s)
- Keshia E Mora
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
- Center for Musculoskeletal Research, Department of Orthopaedics and Rehabilitation, University of Rochester Medical Center, Rochester, NY, 14642, USA
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Samuel J Mlawer
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Alayna E Loiselle
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
- Center for Musculoskeletal Research, Department of Orthopaedics and Rehabilitation, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Mark R Buckley
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
- Center for Musculoskeletal Research, Department of Orthopaedics and Rehabilitation, University of Rochester Medical Center, Rochester, NY, 14642, USA
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Iwasaki N, Karali A, Roldo M, Blunn G. Full-Field Strain Measurements of the Muscle-Tendon Junction Using X-ray Computed Tomography and Digital Volume Correlation. Bioengineering (Basel) 2024; 11:162. [PMID: 38391648 PMCID: PMC10886230 DOI: 10.3390/bioengineering11020162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 02/01/2024] [Indexed: 02/24/2024] Open
Abstract
We report, for the first time, the full-field 3D strain distribution of the muscle-tendon junction (MTJ). Understanding the strain distribution at the junction is crucial for the treatment of injuries and to predict tear formation at this location. Three-dimensional full-field strain distribution of mouse MTJ was measured using X-ray computer tomography (XCT) combined with digital volume correlation (DVC) with the aim of understanding the mechanical behavior of the junction under tensile loading. The interface between the Achilles tendon and the gastrocnemius muscle was harvested from adult mice and stained using 1% phosphotungstic acid in 70% ethanol. In situ XCT combined with DVC was used to image and compute strain distribution at the MTJ under a tensile load (2.4 N). High strain measuring 120,000 µε, 160,000 µε, and 120,000 µε for the first principal stain (εp1), shear strain (γ), and von Mises strain (εVM), respectively, was measured at the MTJ and these values reduced into the body of the muscle or into the tendon. Strain is concentrated at the MTJ, which is at risk of being damaged in activities associated with excessive physical activity.
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Affiliation(s)
- Nodoka Iwasaki
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, UK
| | - Aikaterina Karali
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK
| | - Marta Roldo
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, UK
| | - Gordon Blunn
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, UK
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Dall'Ara E, Tozzi G. Digital volume correlation for the characterization of musculoskeletal tissues: Current challenges and future developments. Front Bioeng Biotechnol 2022; 10:1010056. [PMID: 36267445 PMCID: PMC9577231 DOI: 10.3389/fbioe.2022.1010056] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 09/20/2022] [Indexed: 11/13/2022] Open
Abstract
Biological tissues are complex hierarchical materials, difficult to characterise due to the challenges associated to the separation of scale and heterogeneity of the mechanical properties at different dimensional levels. The Digital Volume Correlation approach is the only image-based experimental approach that can accurately measure internal strain field within biological tissues under complex loading scenarios. In this minireview examples of DVC applications to study the deformation of musculoskeletal tissues at different dimensional scales are reported, highlighting the potential and challenges of this relatively new technique. The manuscript aims at reporting the wide breath of DVC applications in the past 2 decades and discuss future perspective for this unique technique, including fast analysis, applications on soft tissues, high precision approaches, and clinical applications.
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Affiliation(s)
- Enrico Dall'Ara
- Department of Oncology and Metabolism, Mellanby Centre for Bone Research, University of Sheffield, Sheffield, United Kingdom.,INSIGNEO Institute for in Silico Medicine, University of Sheffield, Sheffield, United Kingdom
| | - Gianluca Tozzi
- School of Engineering, University of Greenwich, Chatham Maritime, United Kingdom
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Sun Han Chang RA, Shanley JF, Kersh ME, Harley BAC. Tough and tunable scaffold-hydrogel composite biomaterial for soft-to-hard musculoskeletal tissue interfaces. SCIENCE ADVANCES 2020; 6:eabb6763. [PMID: 32875114 PMCID: PMC7438087 DOI: 10.1126/sciadv.abb6763] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 07/09/2020] [Indexed: 06/11/2023]
Abstract
Tendon inserts into bone via a fibrocartilaginous interface (enthesis) that reduces mechanical strain and tissue failure. Despite this toughening mechanism, tears occur because of acute (overload) or degradative (aging) processes. Surgically fixating torn tendon into bone results in the formation of a scar tissue interface with inferior biomechanical properties. Progress toward enthesis regeneration requires biomaterial approaches to protect cells from high levels of interfacial strain. We report an innovative tissue reinforcement strategy: a stratified scaffold containing osseous and tendinous tissue compartments attached through a continuous polyethylene glycol (PEG) hydrogel interface. Tuning the gelation kinetics of the hydrogel modulates integration with the flanking compartments and yields biomechanical performance advantages. Notably, the hydrogel interface reduces formation of strain concentrations between tissue compartments in conventional stratified biomaterials that can have deleterious biological effects. This design of mechanically robust stratified composite biomaterials may be appropriate for a broad range of tendon and ligament-to-bone insertions.
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Affiliation(s)
- Raul A Sun Han Chang
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - John F Shanley
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Mariana E Kersh
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Brendan A C Harley
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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