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Rich MJ, Burnash S, Krishnan RR, Chubinskaya S, Loeser RF, Polacheck WJ, Diekman BO. Use of a novel magnetically actuated compression system to study the temporal dynamics of axial and lateral strain in human osteochondral plugs. J Biomech 2024; 162:111887. [PMID: 38128469 PMCID: PMC10872462 DOI: 10.1016/j.jbiomech.2023.111887] [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: 06/03/2023] [Revised: 10/23/2023] [Accepted: 11/28/2023] [Indexed: 12/23/2023]
Abstract
The high water content of articular cartilage allows this biphasic tissue to withstand large compressive loads through fluid pressurization. The system presented here, termed the "MagnaSquish", provides new capabilities for quantifying the effect of rehydration on cartilage behavior during cyclic loading. An imbalanced rate of fluid exudation during load and fluid re-entry during recovery can lead to the accumulation of strain during successive loading cycles - a phenomenon known as ratcheting. Typical experimental systems for cartilage biomechanics use continuous contact between the platen and sample, which may affect tissue rehydration by compressing the top layer of cartilage and slowing fluid re-entry. To address this limitation, we developed a magnetically actuated device that provides full lift-off of the platen in between loading cycles. We investigated strain accumulation in cadaveric human osteochondral plugs during 750 loading cycles, with two dimensional profiles of the cartilage captured at 30 frames per second throughout loading and 10 min of additional free swelling recovery. Axial and lateral strain measurements were extracted from the tissue profiles using a UNet-based deep learning algorithm to circumvent manual tracing. We observed increased axial strain accumulation with shorter inter-cycle recovery, with static loading serving as the extreme case of zero recovery. The loading waveform during the 750 cycles dictated the pace of the recovery during the extended free swelling period, as shorter inter-cycle recovery led to more persistent axial strain accumulation for up to five minutes. This work showcases the importance of fluid re-entry in resisting strain accumulation during cyclical compression.
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Affiliation(s)
- Matthew J Rich
- Thurston Arthritis Research Center, University of North Carolina at Chapel Hill (UNC), Chapel Hill, NC, United States; Joint Department of Biomedical Engineering, UNC and North Carolina State University, Raleigh, NC, United States
| | - Sarah Burnash
- Joint Department of Biomedical Engineering, UNC and North Carolina State University, Raleigh, NC, United States
| | - Rohan R Krishnan
- Joint Department of Biomedical Engineering, UNC and North Carolina State University, Raleigh, NC, United States
| | - Susan Chubinskaya
- Department of Pediatrics, Rush University Medical Center, Chicago, IL, United States
| | - Richard F Loeser
- Thurston Arthritis Research Center, University of North Carolina at Chapel Hill (UNC), Chapel Hill, NC, United States; Department of Cell Biology and Physiology, UNC, United States; Division of Rheumatology, Allergy, and Immunology, UNC, United States
| | - William J Polacheck
- Joint Department of Biomedical Engineering, UNC and North Carolina State University, Raleigh, NC, United States; Department of Cell Biology and Physiology, UNC, United States; McAllister Heart Institute, UNC, United States
| | - Brian O Diekman
- Thurston Arthritis Research Center, University of North Carolina at Chapel Hill (UNC), Chapel Hill, NC, United States; Joint Department of Biomedical Engineering, UNC and North Carolina State University, Raleigh, NC, United States; Department of Cell Biology and Physiology, UNC, United States.
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Mohammadkhah M, Klinge S. Review paper: The importance of consideration of collagen cross-links in computational models of collagen-based tissues. J Mech Behav Biomed Mater 2023; 148:106203. [PMID: 37879165 DOI: 10.1016/j.jmbbm.2023.106203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 09/25/2023] [Accepted: 10/17/2023] [Indexed: 10/27/2023]
Abstract
Collagen as the main protein in Extra Cellular Matrix (ECM) is the main load-bearing component of fibrous tissues. Nanostructure and architecture of collagen fibrils play an important role in mechanical behavior of these tissues. Extensive experimental and theoretical studies have so far been performed to capture these properties, but none of the current models realistically represent the complexity of network mechanics because still less is known about the collagen's inner structure and its effect on the mechanical properties of tissues. The goal of this review article is to emphasize the significance of cross-links in computational modeling of different collagen-based tissues, and to reveal the need for continuum models to consider cross-links properties to better reflect the mechanical behavior observed in experiments. In addition, this study outlines the limitations of current investigations and provides potential suggestions for the future work.
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Affiliation(s)
- Melika Mohammadkhah
- Technische Universität Berlin, Institute of Mechanics, Chair of Structural Mechanics and Analysis, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany.
| | - Sandra Klinge
- Technische Universität Berlin, Institute of Mechanics, Chair of Structural Mechanics and Analysis, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
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Henderson BS, Cudworth KF, Peña E, Lujan TJ. Modeling fatigue failure in soft tissue using a visco-hyperelastic model with discontinuous damage. J Mech Behav Biomed Mater 2023; 144:105968. [PMID: 37390777 PMCID: PMC11008526 DOI: 10.1016/j.jmbbm.2023.105968] [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: 07/02/2022] [Revised: 05/19/2023] [Accepted: 06/06/2023] [Indexed: 07/02/2023]
Abstract
Soft tissue is susceptible to injury from single high-magnitude static loads and from repetitive low-magnitude fatigue loads. While many constitutive formulations have been developed and validated to model static failure in soft tissue, a modeling framework is not well-established for fatigue failure. Here we determined the feasibility of using a visco-hyperelastic damage model with discontinuous damage (strain energy-based damage criterion) to simulate low- and high-cycle fatigue failure in soft fibrous tissue. Cyclic creep data from six uniaxial tensile fatigue experiments of human medial meniscus were used to calibrate the specimen-specific material parameters. The model was able to successfully simulate all three characteristic stages of cyclic creep, and predict the number of cycles until tissue rupture. Mathematically, damage propagated under constant cyclic stress due to time-dependent viscoelastic increases in tensile stretch that in turn increased strain energy. Our results implicate solid viscoelasticity as a fundamental regulator of fatigue failure in soft tissue, where tissue with slow stress relaxation times will be more resistant to fatigue injury. In a validation study, the visco-hyperelastic damage model was able to simulate characteristic stress-strain curves of pull to failure experiments (static failure) when using material parameters curve fit to the fatigue experiments. For the first time, we've shown that a visco-hyperelastic discontinuous damage framework can model cyclic creep and predict material rupture in soft tissue, and may enable the reliable simulation of both fatigue and static failure behavior from a single constitutive formulation.
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Affiliation(s)
- Bradley S Henderson
- Department of Mechanical & Biomedical Engineering, Boise State University, Boise, ID, USA
| | - Katelyn F Cudworth
- Department of Mechanical & Biomedical Engineering, Boise State University, Boise, ID, USA
| | - Estefanía Peña
- Department of Mechanical Engineering, University of Zaragoza, Zaragoza, Spain; CIBER-BBN, Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicina, Zaragoza, Spain
| | - Trevor J Lujan
- Department of Mechanical & Biomedical Engineering, Boise State University, Boise, ID, USA.
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