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Zimmerman BK, Nims RJ, Chen A, Hung CT, Ateshian GA. Direct Osmotic Pressure Measurements in Articular Cartilage Demonstrate Nonideal and Concentration-Dependent Phenomena. J Biomech Eng 2021; 143:041007. [PMID: 33210125 PMCID: PMC7872001 DOI: 10.1115/1.4049158] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/01/2020] [Indexed: 11/08/2022]
Abstract
The osmotic pressure in articular cartilage serves an important mechanical function in healthy tissue. Its magnitude is thought to play a role in advancing osteoarthritis. The aims of this study were to: (1) isolate and quantify the magnitude of cartilage swelling pressure in situ; and (2) identify the effect of salt concentration on material parameters. Confined compression stress-relaxation testing was performed on 18 immature bovine and six mature human cartilage samples in solutions of varying osmolarities. Direct measurements of osmotic pressure revealed nonideal and concentration-dependent osmotic behavior, with magnitudes approximately 1/3 those predicted by ideal Donnan law. A modified Donnan constitutive behavior was able to capture the aggregate behavior of all samples with a single adjustable parameter. Results of curve-fitting transient stress-relaxation data with triphasic theory in febio demonstrated concentration-dependent material properties. The aggregate modulus HA increased threefold as the external concentration decreased from hypertonic 2 M to hypotonic 0.001 M NaCl (bovine: HA=0.420±0.109 MPa to 1.266±0.438 MPa; human: HA=0.499±0.208 MPa to 1.597±0.455 MPa), within a triphasic theory inclusive of osmotic effects. This study provides a novel and simple analytical model for cartilage osmotic pressure which may be used in computational simulations, validated with direct in situ measurements. A key finding is the simultaneous existence of Donnan osmotic and Poisson-Boltzmann electrostatic interactions within cartilage.
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Affiliation(s)
- Brandon K Zimmerman
- Department of Mechanical Engineering, Columbia University, New York, NY 10027
| | - Robert J Nims
- Department of Biomedical Engineering, Columbia University, New York, NY 10027
| | - Alex Chen
- Department of Mechanical Engineering, Columbia University, New York, NY 10027
| | - Clark T Hung
- Department of Biomedical Engineering, Columbia University, New York, NY 10027
| | - Gerard A Ateshian
- Department of Mechanical Engineering, Columbia University, New York, NY 10027; Department of Biomedical Engineering, Columbia University, New York, NY 10027
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Todd JN, Allan AN, Maak TG, Weiss JA. Characterization and finite element validation of transchondral strain in the human hip during static and dynamic loading. J Biomech 2021; 114:110143. [PMID: 33307354 PMCID: PMC10714355 DOI: 10.1016/j.jbiomech.2020.110143] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 10/04/2020] [Accepted: 11/12/2020] [Indexed: 10/22/2022]
Abstract
Distribution of strain through the thickness of articular cartilage, or transchondral strain, is highly dependent on the geometry of the joint involved. Excessive transchondral strain can damage the solid matrix and ultimately lead to osteoarthritis. Currently, high-resolution transchondral strain distribution is unknown in the human hip. Thus, knowledge of transchondral strain patterns is of fundamental importance to interpreting the patterns of injury that occur in prearthritic hip joints. This study had three main objectives. We sought to 1) quantify high-resolution transchondral strain in the native human hip, 2) determine differences in transchondral strain between static and dynamic loading conditions to better understand recovery and repressurization of cartilage in the hip, and 3) create finite element (FE) models of the experimental testing to validate a modeling framework for future analysis. The transchondral strain patterns found in this study provide insight on the localization of strain within cartilage of the hip. Most notably, the chondrolabral junction experienced high tensile and shear strain across all samples, which explains clinical data reporting it as the most common region of damage in cartilage of the hip. Further, the representative FE framework was able to match the experimental static results and predict the dynamic results with very good agreement. This agreement provides confidence for both experimental and computational measurement methods and demonstrates that the specific anisotropic biphasic FE framework used in this study can both describe and predict the experimental results.
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Affiliation(s)
- Jocelyn N Todd
- Department of Biomedical Engineering, and Scientific Computing and Imaging Institute University of Utah, Salt Lake City, UT 84112, United States.
| | - Alexandra N Allan
- Department of Biomedical Engineering, and Scientific Computing and Imaging Institute University of Utah, Salt Lake City, UT 84112, United States
| | - Travis G Maak
- Department of Orthopedics, University of Utah, Salt Lake City, UT 84108, United States.
| | - Jeffrey A Weiss
- Department of Biomedical Engineering, and Scientific Computing and Imaging Institute University of Utah, Salt Lake City, UT 84112, United States; Department of Orthopedics, University of Utah, Salt Lake City, UT 84108, United States.
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3
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Effect of strain rate on transient local strain variations in articular cartilage. J Mech Behav Biomed Mater 2019; 95:60-66. [DOI: 10.1016/j.jmbbm.2019.03.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 02/06/2019] [Accepted: 03/20/2019] [Indexed: 11/18/2022]
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4
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Luo W, Liu H, Wang C, Qin Y, Liu Q, Wang J. Bioprinting of Human Musculoskeletal Interface. ADVANCED ENGINEERING MATERIALS 2019; 21:1900019. [DOI: 10.1002/adem.201900019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Indexed: 07/28/2023]
Affiliation(s)
- Wenbin Luo
- Department of OrthopedicsThe Second Hospital of Jilin UniversityChangchun130041P. R. China
| | - He Liu
- Department of OrthopedicsThe Second Hospital of Jilin UniversityChangchun130041P. R. China
| | - Chenyu Wang
- Department of OrthopedicsThe Second Hospital of Jilin UniversityChangchun130041P. R. China
- Hallym University1Hallymdaehak‐gilChuncheonGangwon‐do200‐702Korea
| | - Yanguo Qin
- Department of OrthopedicsThe Second Hospital of Jilin UniversityChangchun130041P. R. China
| | - Qingping Liu
- Key Laboratory of Bionic Engineering (Ministry of Education)Jilin UniversityChangchun130022P. R. China
| | - Jincheng Wang
- Department of OrthopedicsThe Second Hospital of Jilin UniversityChangchun130041P. R. China
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Zevenbergen L, Gsell W, Cai L, Chan DD, Famaey N, Vander Sloten J, Himmelreich U, Neu CP, Jonkers I. Cartilage-on-cartilage contact: effect of compressive loading on tissue deformations and structural integrity of bovine articular cartilage. Osteoarthritis Cartilage 2018; 26:1699-1709. [PMID: 30172835 DOI: 10.1016/j.joca.2018.08.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 08/17/2018] [Accepted: 08/21/2018] [Indexed: 02/09/2023]
Abstract
OBJECTIVE This study aims to characterize the deformations in articular cartilage under compressive loading and link these to changes in the extracellular matrix constituents described by magnetic resonance imaging (MRI) relaxation times in an experimental model mimicking in vivo cartilage-on-cartilage contact. DESIGN Quantitative MRI images, T1, T2 and T1ρ relaxation times, were acquired at 9.4T from bovine femoral osteochondral explants before and immediately after loading. Two-dimensional intra-tissue displacement and strain fields under cyclic compressive loading (350N) were measured using the displacement encoding with stimulated echoes (DENSE) method. Changes in relaxation times in response to loading were evaluated against the deformation fields. RESULTS Deformation fields showed consistent patterns among all specimens, with maximal strains at the articular surface that decrease with tissue depth. Axial and transverse strains were maximal around the center of the contact region, whereas shear strains were minimal around the contact center but increased towards contact edges. A decrease in T2 and T1ρ was observed immediately after loading whereas the opposite was observed for T1. No correlations between cartilage deformation patterns and changes in relaxation times were observed. CONCLUSIONS Displacement encoding combined with relaxometry by MRI can noninvasively monitor the cartilage biomechanical and biochemical properties associated with loading. The deformation fields reveal complex patterns reflecting the depth-dependent mechanical properties, but intra-tissue deformation under compressive loading does not correlate with structural and compositional changes. The compacting effect of cyclic compression on the cartilage tissue was revealed by the change in relaxation time immediately after loading.
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Affiliation(s)
- L Zevenbergen
- Human Movement Biomechanics Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium.
| | - W Gsell
- Biomedical MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.
| | - L Cai
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA.
| | - D D Chan
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA.
| | - N Famaey
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium.
| | - J Vander Sloten
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium.
| | - U Himmelreich
- Biomedical MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.
| | - C P Neu
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA; Department of Mechanical Engineering, University of Colorado Boulder, Colorado, USA.
| | - I Jonkers
- Human Movement Biomechanics Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium.
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Zevenbergen L, Gsell W, Chan DD, Vander Sloten J, Himmelreich U, Neu CP, Jonkers I. Functional assessment of strains around a full-thickness and critical sized articular cartilage defect under compressive loading using MRI. Osteoarthritis Cartilage 2018; 26:1710-1721. [PMID: 30195045 DOI: 10.1016/j.joca.2018.08.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 08/10/2018] [Accepted: 08/29/2018] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The objective of this study was to evaluate the effect of full-thickness chondral defects on intratissue deformation patterns and matrix constituents in an experimental model mimicking in vivo cartilage-on-cartilage contact conditions. DESIGN Pairs of bovine osteochondral explants, in a unique cartilage-on-cartilage model system, were compressed uniaxially by 350 N during 2 s loading and 1.4 s unloading cycles (≈1700 repetitions). Tissue deformations under quasi-steady state load deformation response were measured with displacement encoded imaging with stimulated echoes (DENSE) in a 9.4 T magnetic resonance imaging (MRI) scanner. Pre- and post-loading, T1, T2 and T1ρ relaxation time maps were measured. We analyzed differences in strain patterns and relaxation times between intact cartilage (n = 8) and cartilage in which a full-thickness and critical sized defect was created (n = 8). RESULTS Under compressive loading, strain magnitudes were elevated at the defect rim, with elevated tensile and compressive principal strains (Δϵmax = 4.2%, P = 0.02; Δϵmin = -4.3%, P = 0.02) and maximum shear strain at the defect rim (Δγmax = 4.4%, P = 0.007). The opposing cartilage showed minimal increase in strain patterns at contact with the defect rim but decreased strains opposing the defect. After defect creation, T1, T2 and T1ρ relaxation times were elevated at the defect rim only. Following loading, the overall relaxations times of the defect tissue and especially at the rim, increased compared to intact cartilage. CONCLUSIONS This study demonstrates that the local biomechanical changes occurring after defect creation may induce tissue damage by increasing shear strains and depletion of cartilage constituents at the defect rim under compressive loading.
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Affiliation(s)
- L Zevenbergen
- Department of Movement Sciences, KU Leuven, Leuven, Belgium.
| | - W Gsell
- Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.
| | - D D Chan
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA.
| | - J Vander Sloten
- Department of Mechanical Engineering, KU Leuven, Leuven, Belgium.
| | - U Himmelreich
- Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.
| | - C P Neu
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, USA.
| | - I Jonkers
- Department of Movement Sciences, KU Leuven, Leuven, Belgium.
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7
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Hudnut AW, Trasolini NA, Hatch GFR, Armani AM. Biomechanical Analysis of Porcine Cartilage Elasticity. Ann Biomed Eng 2018; 47:202-212. [PMID: 30251031 DOI: 10.1007/s10439-018-02133-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 09/14/2018] [Indexed: 01/02/2023]
Abstract
Grafting of tissue-engineered cartilage to joints with osteoarthritis has the potential to supersede arthroplasty as the standard of care. However, in order to support the development of functional tissue engineering methods, the subfailure biomechanics of the individual cartilage types that comprise joints must be determined. Current methods for analyzing tissues are based on imaging and are therefore unable to profile the strain dependence of mechanical behaviors within different cartilage types. Recently, an analysis technique based on Optical Fiber Polarimetric Elastography (OFPE) has overcome these challenges. OFPE has been used to characterize the different mechanical behaviors of a range of unprocessed biomaterials and tissues. In the present work, this technique is used to characterize the biomechanics of both articular cartilage and meniscal fibrocartilage within a porcine knee. OFPE testing of the tissue is conducted over a range of physiological loading and unloading values. These results demonstrate the distinctive mechanics of each cartilage type. Due to their different locations within the knee, each cartilage type exhibits distinctly unique biomechanical behavior. Based on the results of OFPE, we correlate the specific buckling, delamination, and bridging events to maxima and minima along the loading and unloading curves. This provides unprecedented detail with regard to the subfailure biomechanics. This information is integral to the design of the next generation of tissue-engineered constructs. Therefore, OFPE will be used across multiple disciplines to rapidly determine the mechanical behavior of tissue-engineered constructs to support functional tissue engineering efforts.
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Affiliation(s)
- Alexa W Hudnut
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Nicholas A Trasolini
- Department of Orthopedic Surgery, University of Southern California, Los Angeles, CA, USA
| | - George F Rick Hatch
- Department of Orthopedic Surgery, University of Southern California, Los Angeles, CA, USA
| | - Andrea M Armani
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA. .,Mork Family Department of Chemical Engineering and Material Science, University of Southern California, Los Angeles, CA, USA.
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8
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Lewis JT, Fischenich KM, Haut Donahue TL, Bailey TS. Nanostructure-Driven Replication of Soft Tissue Biomechanics in a Thermoplastic Elastomer Hydrogel. ACS Biomater Sci Eng 2018; 4:3854-3863. [DOI: 10.1021/acsbiomaterials.8b00929] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jackson T. Lewis
- School of Biomedical Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Kristine M. Fischenich
- School of Biomedical Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Tammy L. Haut Donahue
- Department of Biomedical Engineering, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Travis S. Bailey
- School of Biomedical Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
- Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, Colorado 80523, United States
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9
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Kotelsky A, Woo CW, Delgadillo LF, Richards MS, Buckley MR. An Alternative Method to Characterize the Quasi-Static, Nonlinear Material Properties of Murine Articular Cartilage. J Biomech Eng 2018; 140:2657496. [PMID: 29049670 DOI: 10.1115/1.4038147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Indexed: 11/08/2022]
Abstract
With the onset and progression of osteoarthritis (OA), articular cartilage (AC) mechanical properties are altered. These alterations can serve as an objective measure of tissue degradation. Although the mouse is a common and useful animal model for studying OA, it is extremely challenging to measure the mechanical properties of murine AC due to its small size (thickness < 50 μm). In this study, we developed novel and direct approach to independently quantify two quasi-static mechanical properties of mouse AC: the load-dependent (nonlinear) solid matrix Young's modulus (E) and drained Poisson's ratio (ν). The technique involves confocal microscope-based multiaxial strain mapping of compressed, intact murine AC followed by inverse finite element analysis (iFEA) to determine E and ν. Importantly, this approach yields estimates of E and ν that are independent of the initial guesses used for iterative optimization. As a proof of concept, mechanical properties of AC on the medial femoral condyles of wild-type mice were obtained for both trypsin-treated and control specimens. After proteolytic tissue degradation induced through trypsin treatment, a dramatic decrease in E was observed (compared to controls) at each of the three tested loading conditions. A significant decrease in ν due to trypsin digestion was also detected. These data indicate that the method developed in this study may serve as a valuable tool for comparative studies evaluating factors involved in OA pathogenesis using experimentally induced mouse OA models.
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Affiliation(s)
- Alexander Kotelsky
- Department of Biomedical Engineering, University of Rochester, 207 Goergen Hall, Box 270168, Rochester, NY 14627 e-mail:
| | - Chandler W Woo
- Department of Biomedical Engineering, University of Rochester, 207 Goergen Hall, Box 270168, Rochester, NY 14627 e-mail:
| | - Luis F Delgadillo
- Department of Biomedical Engineering, University of Rochester, 207 Goergen Hall, Box 270168, Rochester, NY 14627 e-mail:
| | - Michael S Richards
- Department of Surgery, School of Medicine and Dentistry, University of Rochester Medical Center, 601 Elmwood Avenue, Rm 2.4153, Rochester, NY 14627 e-mail:
| | - Mark R Buckley
- Department of Biomedical Engineering, University of Rochester, 207 Goergen Hall, Box 270168, Rochester, NY 14627 e-mail:
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Moo EK, Sibole SC, Han SK, Herzog W. Three-dimensional micro-scale strain mapping in living biological soft tissues. Acta Biomater 2018; 70:260-269. [PMID: 29425715 DOI: 10.1016/j.actbio.2018.01.048] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 01/16/2018] [Accepted: 01/30/2018] [Indexed: 10/18/2022]
Abstract
Non-invasive characterization of the mechanical micro-environment surrounding cells in biological tissues at multiple length scales is important for the understanding of the role of mechanics in regulating the biosynthesis and phenotype of cells. However, there is a lack of imaging methods that allow for characterization of the cell micro-environment in three-dimensional (3D) space. The aims of this study were (i) to develop a multi-photon laser microscopy protocol capable of imprinting 3D grid lines onto living tissue at a high spatial resolution, and (ii) to develop image processing software capable of analyzing the resulting microscopic images and performing high resolution 3D strain analyses. Using articular cartilage as the biological tissue of interest, we present a novel two-photon excitation imaging technique for measuring the internal 3D kinematics in intact cartilage at sub-micrometer resolution, spanning length scales from the tissue to the cell level. Using custom image processing software, we provide accurate and robust 3D micro-strain analysis that allows for detailed qualitative and quantitative assessment of the 3D tissue kinematics. This novel technique preserves tissue structural integrity post-scanning, therefore allowing for multiple strain measurements at different time points in the same specimen. The proposed technique is versatile and opens doors for experimental and theoretical investigations on the relationship between tissue deformation and cell biosynthesis. Studies of this nature may enhance our understanding of the mechanisms underlying cell mechano-transduction, and thus, adaptation and degeneration of soft connective tissues. STATEMENT OF SIGNIFICANCE We presented a novel two-photon excitation imaging technique for measuring the internal 3D kinematics in intact cartilage at sub-micrometer resolution, spanning from tissue length scale to cellular length scale. Using a custom image processing software (lsmgridtrack), we provide accurate and robust micro-strain analysis that allowed for detailed qualitative and quantitative assessment of the 3D tissue kinematics. The approach presented here can also be applied to other biological tissues such as meniscus and annulus fibrosus, as well as tissue-engineered tissues for the characterization of their mechanical properties. This imaging technique opens doors for experimental and theoretical investigation on the relationship between tissue deformation and cell biosynthesis. Studies of this nature may enhance our understanding of the mechanisms underlying cell mechano-transduction, and thus, adaptation and degeneration of soft connective tissues.
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Strain rate dependent hyperelastic stress-stretch behavior of a silica nanoparticle reinforced poly (ethylene glycol) diacrylate nanocomposite hydrogel. J Mech Behav Biomed Mater 2017; 75:236-243. [DOI: 10.1016/j.jmbbm.2017.07.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/18/2017] [Accepted: 07/21/2017] [Indexed: 01/15/2023]
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O’Connell G, Garcia J, Amir J. 3D Bioprinting: New Directions in Articular Cartilage Tissue Engineering. ACS Biomater Sci Eng 2017; 3:2657-2668. [DOI: 10.1021/acsbiomaterials.6b00587] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Grace O’Connell
- Department
of Mechanical Engineering University of California, Berkeley, 5122 Etcheverry Hall, Berkeley, California 94720, United States
| | - Jeanette Garcia
- IBM Research-Almaden, 650
Harry Road K17/D2, San Jose, California 95120, United States
| | - Jamali Amir
- Joint Preservation Institute, 2825 J Street #440, Sacramento, California 95816, United States
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Moo EK, Herzog W. Unfolding of membrane ruffles of in situ chondrocytes under compressive loads. J Orthop Res 2017; 35:304-310. [PMID: 27064602 DOI: 10.1002/jor.23260] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 03/31/2016] [Indexed: 02/04/2023]
Abstract
Impact loading results in chondrocyte death. Previous studies implicated high tensile strain rates in chondrocyte membranes as the cause of impact-induced cell deaths. However, this hypothesis relies on the untested assumption that chondrocyte membranes unfold in vivo during physiological tissue compression, but do not unfold during impact loading. Although membrane unfolding has been observed in isolated chondrocytes during osmotically induced swelling and mechanical compression, it is not known if membrane unfolding also occurs in chondrocytes embedded in their natural extracellular matrix. This study was aimed at quantifying changes in membrane morphology of in situ superficial zone chondrocytes during slow physiological cartilage compression. Bovine cartilage-bone explants were loaded at 5 μm/s to nominal compressive strains ranging from 0% to 50%. After holding the final strains for 45 min, the loaded cartilage was chemically pre-fixed for 12 h. The cartilage layer was post-processed for visualization of cell ultrastructure using electron microscopy. The changes in membrane morphology in superficial zone cells were quantified from planar electron micrographs by measuring the roughness and the complexity of the cell surfaces. Qualitatively, the cell surface ruffles that existed before loading disappeared when cartilage was loaded. Quantitatively, the roughness and complexity of cell surfaces decreased with increasing load magnitudes, suggesting a load-dependent use of membrane reservoirs. Chondrocyte membranes unfold in a load-dependent manner when cartilage is compressed. Under physiologically meaningful loading conditions, the cells likely expand their surface through unfolding of the membrane ruffles, and therefore avoid direct stretch of the cell membrane. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:304-310, 2017.
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Affiliation(s)
- Eng Kuan Moo
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, T2N 1N4, Canada
| | - Walter Herzog
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, T2N 1N4, Canada
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14
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Trumbull A, Subramanian G, Yildirim-Ayan E. Mechanoresponsive musculoskeletal tissue differentiation of adipose-derived stem cells. Biomed Eng Online 2016; 15:43. [PMID: 27103394 PMCID: PMC4840975 DOI: 10.1186/s12938-016-0150-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 03/24/2016] [Indexed: 02/06/2023] Open
Abstract
Musculoskeletal tissues are constantly under mechanical strains within their microenvironment. Yet, little is understood about the effect of in vivo mechanical milieu strains on cell development and function. Thus, this review article outlines the in vivo mechanical environment of bone, muscle, cartilage, tendon, and ligaments, and tabulates the mechanical strain and stress in these tissues during physiological condition, vigorous, and moderate activities. This review article further discusses the principles of mechanical loading platforms to create physiologically relevant mechanical milieu in vitro for musculoskeletal tissue regeneration. A special emphasis is placed on adipose-derived stem cells (ADSCs) as an emerging valuable tool for regenerative musculoskeletal tissue engineering, as they are easily isolated, expanded, and able to differentiate into any musculoskeletal tissue. Finally, it highlights the current state-of-the art in ADSCs-guided musculoskeletal tissue regeneration under mechanical loading.
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Affiliation(s)
- Andrew Trumbull
- Department of Bioengineering, College of Engineering, University of Toledo, Toledo, OH, 43606, USA
| | - Gayathri Subramanian
- Department of Bioengineering, College of Engineering, University of Toledo, Toledo, OH, 43606, USA
| | - Eda Yildirim-Ayan
- Department of Bioengineering, College of Engineering, University of Toledo, Toledo, OH, 43606, USA. .,Department of Orthopaedic Surgery, University of Toledo Medical Center, Toledo, OH, 43614, USA.
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15
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Bourne DA, Moo EK, Herzog W. Cartilage and chondrocyte response to extreme muscular loading and impact loading: Can in vivo pre-load decrease impact-induced cell death? Clin Biomech (Bristol, Avon) 2015; 30:537-45. [PMID: 25957254 DOI: 10.1016/j.clinbiomech.2015.04.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 04/14/2015] [Accepted: 04/16/2015] [Indexed: 02/07/2023]
Abstract
BACKGROUND Impact loading causes cartilage damage and cell death. Pre-loading prior to impact loading may protect cartilage and chondrocytes. However, there is no systematic evidence and understanding of the effects of pre-load strategies on cartilage damage and chondrocyte death. This study aimed at determining the effects of the pre-load history on impact-induced chondrocyte death in an intact joint. METHODS Patellofemoral joints from 42 rabbits were loaded by controlled quadriceps muscle contractions and an external impacter. Two extreme muscular loading conditions were used: (i) a short-duration, high intensity, static muscle contraction, and (ii) a long-duration, low-intensity, cyclic muscle loading protocol. A 5-Joule centrally-oriented, gravity-accelerated impact load was applied to the joints. Chondrocyte viability was quantified following the muscular loading protocols, following application of the isolated impact loads, and following application of the impact loads that were preceded by the muscular pre-loads. Joint contact pressures were measured for all loading conditions by a pressure-sensitive film. FINDINGS Comparing to cartilage injured by impact loading alone, cartilage pre-loaded by static, maximal intensity, short-term muscle loads had lower cell death, while cartilage pre-loaded by repetitive, low-intensity, long-term muscular loads has higher cell death. The locations of peak joint contact pressures were not strongly correlated with the locations of greatest cell death occurrence. INTERPRETATION Static, high intensity, short muscular pre-load protected cells from impact injury, whereas repetitive, low intensity, prolonged muscular pre-loading to the point of muscular fatigue left the chondrocytes vulnerable to injury. However, cell death seems to be unrelated to the peak joint pressures.
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Affiliation(s)
- Douglas A Bourne
- Human Performance Laboratory, Faculty of Kinesiology, The University of Calgary, Calgary, Alberta, Canada
| | - Eng Kuan Moo
- Human Performance Laboratory, Faculty of Kinesiology, The University of Calgary, Calgary, Alberta, Canada
| | - Walter Herzog
- Human Performance Laboratory, Faculty of Kinesiology, The University of Calgary, Calgary, Alberta, Canada.
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Henak CR, Ateshian GA, Weiss JA. Finite element prediction of transchondral stress and strain in the human hip. J Biomech Eng 2014; 136:021021. [PMID: 24292495 DOI: 10.1115/1.4026101] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 11/27/2013] [Indexed: 11/08/2022]
Abstract
Cartilage fissures, surface fibrillation, and delamination represent early signs of hip osteoarthritis (OA). This damage may be caused by elevated first principal (most tensile) strain and maximum shear stress. The objectives of this study were to use a population of validated finite element (FE) models of normal human hips to evaluate the required mesh for converged predictions of cartilage tensile strain and shear stress, to assess the sensitivity to cartilage constitutive assumptions, and to determine the patterns of transchondral stress and strain that occur during activities of daily living. Five specimen-specific FE models were evaluated using three constitutive models for articular cartilage: quasilinear neo-Hookean, nonlinear Veronda Westmann, and tension-compression nonlinear ellipsoidal fiber distribution (EFD). Transchondral predictions of maximum shear stress and first principal strain were determined. Mesh convergence analysis demonstrated that five trilinear elements were adequate through the depth of the cartilage for precise predictions. The EFD model had the stiffest response with increasing strains, predicting the largest peak stresses and smallest peak strains. Conversely, the neo-Hookean model predicted the smallest peak stresses and largest peak strains. Models with neo-Hookean cartilage predicted smaller transchondral gradients of maximum shear stress than those with Veronda Westmann and EFD models. For FE models with EFD cartilage, the anterolateral region of the acetabulum had larger peak maximum shear stress and first principal strain than all other anatomical regions, consistent with observations of cartilage damage in disease. Results demonstrate that tension-compression nonlinearity of a continuous fiber distribution exhibiting strain induced anisotropy incorporates important features that have large effects on predictions of transchondral stress and strain. This population of normal hips provides baseline data for future comparisons to pathomorphologic hips. This approach can be used to evaluate these and other mechanical variables in the human hip and their potential role in the pathogenesis of osteoarthritis (OA).
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O’Connell G, Nims R, Green J, Cigan A, Ateshian G, Hung C. Time and dose-dependent effects of chondroitinase ABC on growth of engineered cartilage. Eur Cell Mater 2014; 27:312-20. [PMID: 24760578 PMCID: PMC4096549 DOI: 10.22203/ecm.v027a22] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Tissue engineering techniques have been effective in developing cartilage-like tissues in vitro. However, many scaffold-based approaches to cultivating engineered cartilage have been limited by low collagen production, an impediment for attaining native functional load-bearing tensile mechanical properties. Enzymatic digestion of glycosaminoglycans (GAG) with chondroitinase ABC (chABC) temporarily suppresses the construct's GAG content and compressive modulus and increases collagen content. Based on the promising results of these early studies, the aim of this study was to further promote collagen deposition through more frequent chABC treatments. Weekly dosing of chABC at a concentration of 0.15 U/mL resulted in a significant cell death, which impacted the ability of the engineered cartilage to fully recover GAG and compressive mechanical properties. In light of these findings, the influence of lower chABC dosage on engineered tissue (0.004 and 0.015 U/mL) over a longer duration (one week) was investigated. Treatment with 0.004 U/mL reduced cell death, decreased the recovery time needed to achieve native compressive mechanical properties and GAG content, and resulted in a collagen content that was 65 % greater than the control. In conclusion, the results of this study demonstrate that longer chABC treatment (one week) at low concentrations can be used to improve collagen content in developing engineered cartilage more expediently than standard chABC treatments of higher chABC doses administered over brief durations.
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Affiliation(s)
- G.D. O’Connell
- Department of Mechanical Engineering, University of California, Berkeley, CA, USA
| | - R.J. Nims
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - J. Green
- Department of Orthopaedic Surgery, St Luke’s Roosevelt Hospital Center, New York, NY, USA
| | - A.D. Cigan
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - G.A. Ateshian
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - C.T. Hung
- Department of Biomedical Engineering, Columbia University, New York, NY, USA,Address for correspondence: Clark T. Hung, Ph.D. Columbia University, Biomedical Engineering Department, 351 Engineering Terrace, New York, NY 10027, USA, Telephone Number: 212-854-6542, FAX Number: 212-854-8725,
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18
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Extracellular matrix integrity affects the mechanical behaviour of in-situ chondrocytes under compression. J Biomech 2014; 47:1004-13. [PMID: 24480705 DOI: 10.1016/j.jbiomech.2014.01.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 12/31/2013] [Accepted: 01/03/2014] [Indexed: 11/22/2022]
Abstract
Cartilage lesions change the microenvironment of cells and may accelerate cartilage degradation through catabolic responses from chondrocytes. In this study, we investigated the effects of structural integrity of the extracellular matrix (ECM) on chondrocytes by comparing the mechanics of cells surrounded by an intact ECM with cells close to a cartilage lesion using experimental and numerical methods. Experimentally, 15% nominal compression was applied to bovine cartilage tissues using a light-transmissible compression system. Target cells in the intact ECM and near lesions were imaged by dual-photon microscopy. Changes in cell morphology (N(cell)=32 for both ECM conditions) were quantified. A two-scale (tissue level and cell level) Finite Element (FE) model was also developed. A 15% nominal compression was applied to a non-linear, biphasic tissue model with the corresponding cell level models studied at different radial locations from the centre of the sample in the transient phase and at steady state. We studied the Green-Lagrange strains in the tissue and cells. Experimental and theoretical results indicated that cells near lesions deform less axially than chondrocytes in the intact ECM at steady state. However, cells near lesions experienced large tensile strains in the principal height direction, which are likely associated with non-uniform tissue radial bulging. Previous experiments showed that tensile strains of high magnitude cause an up-regulation of digestive enzyme gene expressions. Therefore, we propose that cartilage degradation near tissue lesions may be due to the large tensile strains in the principal height direction applied to cells, thus leading to an up-regulation of catabolic factors.
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Bougault C, Cueru L, Bariller J, Malbouyres M, Paumier A, Aszodi A, Berthier Y, Mallein-Gerin F, Trunfio-Sfarghiu AM. Alteration of cartilage mechanical properties in absence of β1 integrins revealed by rheometry and FRAP analyses. J Biomech 2013; 46:1633-40. [DOI: 10.1016/j.jbiomech.2013.04.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 04/08/2013] [Accepted: 04/14/2013] [Indexed: 10/26/2022]
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20
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Albro MB, Nims RJ, Cigan AD, Yeroushalmi KJ, Shim JJ, Hung CT, Ateshian GA. Dynamic mechanical compression of devitalized articular cartilage does not activate latent TGF-β. J Biomech 2013; 46:1433-9. [PMID: 23540376 DOI: 10.1016/j.jbiomech.2013.03.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 02/27/2013] [Accepted: 03/06/2013] [Indexed: 11/24/2022]
Abstract
A growing body of research has highlighted the role that mechanical forces play in the activation of latent TGF-β in biological tissues. In synovial joints, it has recently been demonstrated that the mechanical shearing of synovial fluid, induced during joint motion, rapidly activates a large fraction of its soluble latent TGF-β content. Based on this observation, the primary hypothesis of the current study is that the mechanical deformation of articular cartilage, induced by dynamic joint motion, can similarly activate the large stores of latent TGF-β bound to the tissue extracellular matrix (ECM). Here, devitalized deep zone articular cartilage cylindrical explants (n=84) were subjected to continuous dynamic mechanical loading (low strain: ±2% or high strain: ±7.5% at 0.5Hz) for up to 15h or maintained unloaded. TGF-β activation was measured in these samples over time while accounting for the active TGF-β that remains bound to the cartilage ECM. Results indicate that TGF-β1 is present in cartilage at high levels (68.5±20.6ng/mL) and resides predominantly in the latent form (>98% of total). Under dynamic loading, active TGF-β1 levels did not statistically increase from the initial value nor the corresponding unloaded control values for any test, indicating that physiologic dynamic compression of cartilage is unable to directly activate ECM-bound latent TGF-β via purely mechanical pathways and leading us to reject the hypothesis of this study. These results suggest that deep zone articular chondrocytes must alternatively obtain access to active TGF-β through chemical-mediated activation and further suggest that mechanical deformation is unlikely to directly activate the ECM-bound latent TGF-β of various other tissues, such as muscle, ligament, and tendon.
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Affiliation(s)
- Michael B Albro
- Department of Mechanical Engineering, Columbia University, 500 West 120th Street, 220 S.W. Mudd, NY 10027, USA.
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21
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Diurnal variations in articular cartilage thickness and strain in the human knee. J Biomech 2012; 46:541-7. [PMID: 23102493 DOI: 10.1016/j.jbiomech.2012.09.013] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 09/26/2012] [Accepted: 09/28/2012] [Indexed: 11/21/2022]
Abstract
Due to the biphasic viscoelastic nature of cartilage, joint loading may result in deformations that require times on the order of hours to fully recover. Thus, cartilaginous tissues may exhibit cumulative strain over the course of each day. The goal of this study was to assess the magnitude and spatial distribution of strain in the articular cartilage of the knee with daily activity. Magnetic resonance (MR) images of 10 asymptomatic subjects (six males and four females) with mean age of 29 years were obtained at 8:00 AM and 4:00 PM on the same day using a 3T magnet. These images were used to create 3D models of the femur, tibia, and patella from which cartilage thickness distributions were quantified. Cartilage thickness generally decreased from AM to PM in all areas except the patellofemoral groove and was associated with significant compressive strains in the medial condyle and tibial plateau. From AM to PM, cartilage of the medial tibial plateau exhibited a compressive strain of -5.1±1.0% (mean±SEM) averaged over all locations, while strains in the lateral plateau were slightly lower (-3.1±0.6%). Femoral cartilage showed an average strain of -1.9±0.6%. The findings of this study show that human knee cartilage undergoes diurnal changes in strain that vary with site in the joint. Since abnormal joint loading can be detrimental to cartilage homeostasis, these data provide a baseline for future studies investigating the effects of altered biomechanics on diurnal cartilage strains and cartilage physiology.
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Borotikar BS, Sipprell WH, Wible EE, Sheehan FT. A methodology to accurately quantify patellofemoral cartilage contact kinematics by combining 3D image shape registration and cine-PC MRI velocity data. J Biomech 2012; 45:1117-22. [PMID: 22284428 PMCID: PMC3310346 DOI: 10.1016/j.jbiomech.2011.12.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 11/28/2011] [Accepted: 12/31/2011] [Indexed: 11/27/2022]
Abstract
Patellofemoral osteoarthritis and its potential precursor patellofemoral pain syndrome (PFPS) are common, costly, and debilitating diseases. PFPS has been shown to be associated with altered patellofemoral joint mechanics; however, an actual variation in joint contact stresses has not been established due to challenges in accurately quantifying in vivo contact kinematics (area and location). This study developed and validated a method for tracking dynamic, in vivo cartilage contact kinematics by combining three magnetic resonance imaging (MRI) techniques, cine-phase contrast (CPC), multi-plane cine (MPC), and 3D high-resolution static imaging. CPC and MPC data were acquired from 12 healthy volunteers while they actively extended/flexed their knee within the MRI scanner. Since no gold standard exists for the quantification of in vivo dynamic cartilage contact kinematics, the accuracy of tracking a single point (patellar origin relative to the femur) represented the accuracy of tracking the kinematics of an entire surface. The accuracy was determined by the average absolute error between the PF kinematics derived through registration of MPC images to a static model and those derived through integration of the CPC velocity data. The accuracy ranged from 0.47 mm to 0.77 mm for the patella and femur and from 0.68 mm to 0.86 mm for the patellofemoral joint. For purely quantifying joint kinematics, CPC remains an analytically simpler and more accurate (accuracy <0.33 mm) technique. However, for application requiring the tracking of an entire surface, such as quantifying cartilage contact kinematics, this combined imaging approach produces accurate results with minimal operator intervention.
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Affiliation(s)
- Bhushan S. Borotikar
- Functional and Applied Biomechanics, Department of Rehabilitation Medicine, NIH, Bethesda, MD, USA
| | - William H. Sipprell
- University at Buffalo, School of Medicine and Biomedical Sciences, Buffalo, NY, USA
| | - Emily E. Wible
- Functional and Applied Biomechanics, Department of Rehabilitation Medicine, NIH, Bethesda, MD, USA
| | - Frances T. Sheehan
- Functional and Applied Biomechanics, Department of Rehabilitation Medicine, NIH, Bethesda, MD, USA
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Thomas RS, Clarke AR, Duance VC, Blain EJ. Effects of Wnt3A and mechanical load on cartilage chondrocyte homeostasis. Arthritis Res Ther 2011; 13:R203. [PMID: 22151902 PMCID: PMC3334656 DOI: 10.1186/ar3536] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 11/02/2011] [Accepted: 12/09/2011] [Indexed: 12/23/2022] Open
Abstract
Introduction Articular cartilage functions in withstanding mechanical loads and provides a lubricating surface for frictionless movement of joints. Osteoarthritis, characterised by cartilage degeneration, develops due to the progressive erosion of structural integrity and eventual loss of functional performance. Osteoarthritis is a multi-factorial disorder; two important risk factors are abnormal mechanical load and genetic predisposition. A single nucleotide polymorphism analysis demonstrated an association of hip osteoarthritis with an Arg324Gly substitution mutation in FrzB, a Wnt antagonist. The purpose of this study was two-fold: to assess whether mechanical stimulation modulates β-catenin signalling and catabolic gene expression in articular chondrocytes, and further to investigate whether there is an interplay of mechanical load and Wnt signalling in mediating a catabolic response. Methods Chondrocytes were pre-stimulated with recombinant Wnt3A for 24 hours prior to the application of tensile strain (7.5%, 1 Hz) for 30 minutes. Activation of Wnt signalling, via β-catenin nuclear translocation and downstream effects including the transcriptional activation of c-jun, c-fos and Lef1, markers of chondrocyte phenotype (type II collagen (col2a1), aggrecan (acan), SOX9) and catabolic genes (MMP3, MMP13, ADAMTS-4, ADAMTS-5) were assessed. Results Physiological tensile strain induced col2a1, acan and SOX9 transcription. Load-induced acan and SOX9 expression were repressed in the presence of Wnt3A. Load induced partial β-catenin nuclear translocation; there was an additive effect of load and Wnt3A on β-catenin distribution, with both extensive localisation in the nucleus and cytoplasm. Immediate early response (c-jun) and catabolic genes (MMP3, ADAMTS-4) were up-regulated in Wnt3A stimulated chondrocytes. With load and Wnt3A there was an additive up-regulation of c-fos, MMP3 and ADAMTS-4 transcription, whereas there was a synergistic interplay on c-jun, Lef1 and ADAMTS-5 transcription. Conclusion Our data suggest that load and Wnt, in combination, can repress transcription of chondrocyte matrix genes, whilst enhancing expression of catabolic mediators. Future studies will investigate the respective roles of abnormal loading and genetic predisposition in mediating cartilage degeneration.
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Affiliation(s)
- Rhian S Thomas
- Welsh School of Pharmacy, Redwood Building, Cardiff University, King Edward VII Avenue, Cardiff, CF10 3NB, UK
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Bischof JE, Spritzer CE, Caputo AM, Easley ME, DeOrio JK, Nunley JA, DeFrate LE. In vivo cartilage contact strains in patients with lateral ankle instability. J Biomech 2011; 43:2561-6. [PMID: 20605154 DOI: 10.1016/j.jbiomech.2010.05.013] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 04/22/2010] [Accepted: 05/12/2010] [Indexed: 12/26/2022]
Abstract
Damage to the anterior talofibular ligament (ATFL) and cacaneofibular ligament (CFL) during an ankle sprain may be linked to the development of osteoarthritis. Although altered tibiotalar kinematics have been demonstrated, the effects of lateral ankle instability (LAI) on in vivo cartilage strains have not been described. We hypothesized that peak cartilage strains increase, and the location is shifted in patients with ATFL injuries. We used 3-D MRI models and biplanar fluoroscopy to evaluate in vivo cartilage contact strains in seven patients with unilateral LAI. Subjects had chronic unilateral ATFL injury or combined ATFL and CFL injury, and were evaluated with increasing load while stepping onto a force plate. Peak cartilage strain and the location of the peak strain were measured using the contralateral normal ankle as a control. Ankles with LAI demonstrated significantly increased peak strain when compared with ATFL-intact controls. For example, at 100% body weight, peak strain was 29+/-8% on the injured side compared to 21+/-5% on the intact side. The position of peak strain on the injured ankle also showed significant anterior translation and medial translation. At 100% body weight, the location of peak strain in the injured ankle translated anteriorly by 15.5+/-7.1mm and medially by 12.9+/-4.3mm relative to the intact ankle. These changes correspond to the region of clinically observed osteoarthritis. Chronic LAI, therefore, may contribute to the development of tibiotalar cartilage degeneration due to altered cartilage strains.
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Wong BL, Sah RL. Effect of a focal articular defect on cartilage deformation during patello-femoral articulation. J Orthop Res 2010; 28:1554-61. [PMID: 20602462 PMCID: PMC3401191 DOI: 10.1002/jor.21187] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The objective of this study was to determine cartilage strains near, and in apposition to, a focal defect during patello-femoral articulation. Bovine osteochondral blocks from the trochlea (TRO) and patella (PAT) were apposed, compressed 12%, and subjected to sliding under video microscopy. Samples, lubricated with synovial fluid, were tested intact and then with a full-thickness defect in PAT cartilage. Shear (E(xz)), axial (E(zz)), and lateral (E(xx)) strains were determined locally for TRO and PAT cartilage. For articulation with a focal defect, the strain amplitudes of PAT cartilage near the surface were ∼2-8× lower in E(xz) and ∼1.4× higher in -E(zz) than intact PAT cartilage. At 20% depth, E(xz) and E(xx) for PAT cartilage with a focal defect were ∼2× and ∼10-25× higher than intact PAT, respectively. For TRO articulating against a focal defect, E(xz) and -E(zz) near the surface and at 20% depth were ∼2-4× lower than that for articulation against intact cartilage. The results elucidate dramatic region-specific changes in strain due to lateral motion. In these regions, such altered cartilage mechanics during knee movement may cause focal defects to extend by induction of damaging levels of strain to bordering regions of cartilage.
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Affiliation(s)
- Benjamin L. Wong
- Department of Bioengineering, University of California–San Diego, La Jolla, CA
| | - Robert L. Sah
- Department of Bioengineering, University of California–San Diego, La Jolla, CA.,Address correspondence and reprint requests to Robert L. Sah, MD, ScD, Department of Bioengineering, Mail Code 0412, University of California–San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412. Tel: (858) 534-0821. Fax: (858) 822-1614.
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James DF, Fick GM, Baines WD. A mechanism to explain physiological lubrication. J Biomech Eng 2010; 132:071002. [PMID: 20590280 DOI: 10.1115/1.4001422] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A new mechanism of physiological lubrication is proposed to explain how low-viscosity synovial fluid prevents articular surfaces from contacting and wearing. The new mechanism is based on the hypothesis that the hyaluronic acid chains in synovial fluid bind to the cartilage surfaces through electrostatic charges, with the phospholipid layer on an articular surface supplying the necessary attractive charges. The stationary hyaluronic acid network causes a large hydrodynamic resistance to outward flow from the gap. To determine the effectiveness of the network in preventing contact, squeeze-film flow between two incompressible, permeable disks is analyzed when a constant load is suddenly applied, and the solvent--synovial fluid minus the hyaluronic acid--escapes through the network and through the permeable disks. The analysis yields the approximate time for the gap distance to decrease to asperity size. For realistic physiological parameters, the time for the surfaces to contact is a minimum of several minutes and likely much longer. The role of albumin in the synovial fluid is included because the large protein molecules are trapped by the small openings in the hyaluronic acid network, which increases the flow resistance of the network and thereby delays contact of the surfaces.
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Affiliation(s)
- David F James
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto M5S 3G8, Canada.
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Lai JH, Levenston ME. Meniscus and cartilage exhibit distinct intra-tissue strain distributions under unconfined compression. Osteoarthritis Cartilage 2010; 18:1291-9. [PMID: 20633686 PMCID: PMC3268046 DOI: 10.1016/j.joca.2010.05.020] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Revised: 05/02/2010] [Accepted: 05/29/2010] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To examine the functional behavior of the surface layer of the meniscus by investigating depth-varying compressive strains during unconfined compression. DESIGN Pairs of meniscus and articular cartilage explants (n=12) site-matched at the tibial surfaces were subjected to equilibrium unconfined compression at 5, 10, 15, and 20% compression under fluorescence imaging. Two-dimensional (2D) deformations were tracked using digital image correlation (DIC). For each specimen, local compressive engineering strains were determined in 200 μm layers through the depth of the tissue. In samples with sharp strain transitions, bilinear regressions were used to characterize the surface and interior tissue compressive responses. RESULTS Meniscus and cartilage exhibited distinct depth-dependent strain profiles during unconfined compression. All cartilage explants had elevated compressive engineering strains near the surface, consistent with previous reports. In contrast, half of the meniscus explants tested had substantially stiffer surface layers, as indicated by surface engineering strains that were ∼20% of the applied compression. In the remaining samples, surface and interior engineering strains were comparable. 2D Green's strain maps revealed highly heterogeneous compressive and shear strains throughout the meniscus explants. In cartilage, the maximum shear strain appeared to be localized at 100-250 μm beneath the articular surface. CONCLUSIONS Meniscus was characterized by highly heterogeneous strains during compression. In contrast to cartilage, which consistently had a compliant surface region, meniscal explants were either substantially stiffer near the surface or had comparable compressive stiffness through the depth. The relatively compliant interior may allow the meniscus to maintain a consistent surface contour while deforming during physiologic loading.
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Affiliation(s)
| | - Marc E. Levenston
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305-4038,Correspondence to: Marc E. Levenston, Ph.D., Department of Mechanical Engineering, 233 Durand Building, Stanford University, Stanford, CA 94305-4038, 650.723.9464 (P), 650.725.1587 (F),
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