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Fischenich KM, Schneider SE, Neu CP, Payne KA, Ferguson VL. Material properties and strain distribution patterns of bovine growth plate cartilage vary with anatomic location and depth. J Biomech 2022; 134:111013. [PMID: 35245713 PMCID: PMC9651143 DOI: 10.1016/j.jbiomech.2022.111013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 02/14/2022] [Accepted: 02/15/2022] [Indexed: 11/29/2022]
Abstract
The aim of this study was to assess the bulk material properties and depth-dependent strain distribution of bovine growth plate cartilage. We hypothesized that both moduli and strain distribution are highly depth-, orientation-, and location-dependent. Bovine proximal tibiae (1-month-old) were sliced along the sagittal and coronal planes to create ∼ 4 mm2 samples. Digital image correlation (DIC) was combined with stress relaxation tests for evaluation of bulk modulus (tangent and equilibrium) and depth-dependent strain distribution. A subset of samples was imaged after Col-F staining as well as histological staining (Safranin-O/Fast Green) to evaluate zonal organization and matrix composition. The mean tangent modulus was 4.25 ± 2.46 MPa while the equilibrium modulus was 0.86 ± 0.46 MPa. No significant differences in moduli were found with respect to orientation (sagittal vs coronal face), but sagittal location within the joint was a significant predictor for tangent modulus. Overall moduli values decreased from the periphery to the midline of the joint. Depth-dependent cellular organization, determined by cell density and shape, was highly variable. This heterogeneity may be a biological toughening mechanism. Peak normalized strains were observed most often in the hypertrophic zone. Modulus was significantly lower in the hypertrophic zone as compared to the resting and proliferative zones. This study is the first to evaluate moduli and strain distribution in intact growth plates as a function of depth, orientation, and anatomic location. Future work with growth plate tissue engineering should consider the location- and depth-dependent nature of the native tissue mechanical properties when designing mimetic constructs.
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Affiliation(s)
- Kristine M Fischenich
- Paul M. Rady Department of Mechanical Engineering, University of Colorado, Boulder, CO, USA; Department of Orthopedics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Stephanie E Schneider
- Paul M. Rady Department of Mechanical Engineering, University of Colorado, Boulder, CO, USA
| | - Corey P Neu
- Paul M. Rady Department of Mechanical Engineering, University of Colorado, Boulder, CO, USA; BioFrontiers Institute, University of Colorado, Boulder, CO, USA; Biomedical Engineering Program, University of Colorado, Boulder, CO, USA
| | - Karin A Payne
- Department of Orthopedics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Virginia L Ferguson
- Paul M. Rady Department of Mechanical Engineering, University of Colorado, Boulder, CO, USA; BioFrontiers Institute, University of Colorado, Boulder, CO, USA; Biomedical Engineering Program, University of Colorado, Boulder, CO, USA
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2
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Eckstein KN, Thomas SM, Scott AK, Neu CP, Payne KA, Ferguson VL. The heterogeneous mechanical properties of adolescent growth plate cartilage: A study in rabbit. J Mech Behav Biomed Mater 2022; 128:105102. [PMID: 35203020 PMCID: PMC9047008 DOI: 10.1016/j.jmbbm.2022.105102] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/08/2022] [Accepted: 01/21/2022] [Indexed: 01/01/2023]
Abstract
The growth plate is a cartilaginous tissue that functions to lengthen bones in children. When fractured, however, the growth plate can lose this critical function. Our understanding of growth plate fracture and mechanobiology is currently hindered by sparse information on the growth plate's microscale spatial gradients in mechanical properties. In this study, we performed microindentation across the proximal tibia growth plate of 9-week-old New Zealand White rabbits (n = 15) to characterize spatial variations in mechanical properties using linear elastic and nonlinear poroelastic material models. Mean indentation results for Hertz reduced modulus ranged from 380 to 690 kPa, with a peak in the upper hypertrophic zone and significant differences (p < 0.05) between neighboring zones. Using a subset of these animals (n = 7), we characterized zonal structure and extracellular matrix content of the growth plate through confocal fluorescent microscopy and Raman spectroscopy mapping. Comparison between mechanical properties and matrix content across the growth plate showed that proteoglycan content correlated with compressive modulus. This study is the first to measure poroelastic mechanical properties from microindentation across growth plate cartilage and to discern differing mechanical properties between the upper and lower hypertrophic zones. This latter finding may explain the location of typical growth plate fractures. The spatial variation in our reported mechanical properties emphasize the heterogeneous structure of the growth plate which is important to inform future regenerative implant design and mechanobiological models.
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3
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Lemirre T, Santschi EM, Girard CA, Fogarty U, Janes JG, Richard H, Laverty S. Microstructural features of subchondral radiolucent lesions in the medial femoral condyle of juvenile Thoroughbreds: A microcomputed tomography and histological analysis. Equine Vet J 2021; 54:601-613. [PMID: 34117652 DOI: 10.1111/evj.13486] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 05/28/2021] [Accepted: 06/03/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND The aetiology of equine medial femoral condyle (MFC) subchondral bone radiolucencies (SR) is unknown. OBJECTIVES Characterise the microstructural structural features of MFC SR in juvenile Thoroughbreds with microcomputed tomography (μCT) and histology. STUDY DESIGN Cross-sectional post-mortem study. METHODS Distal femurs were collected at post-mortem. Conventional tomodensitometry was employed to scout for MFCs with and without SR lesions (SR+ and SR-, respectively). Group 1 were CT MFC SR+ and Group 2 age-matched SR- controls. Both underwent μCT and histological analysis. Group 3 CT MFC SR- foals, <6 months, were selected to search for chondronecrosis. Histological sections, processed from the lesion (Group 1) and a corresponding site in Groups 2 and 3, were assessed for chondronecrosis, fibrin, fibroplasia and osteochondral separation. Group 3 sections were surveyed for chondronecrosis alone. RESULTS A total of 178 femurs from 89 Thoroughbreds were harvested. Of these horses 19.1% (95% CI: 10.9%-27.3%) were CT MFC SR+ (17/23; 7.46 ± 4.36 months) and met the inclusion criteria for Group 1. Group 2 included 30 CT MFC SR- specimens (5.00 ± 2.73 months) and Group 3 had 44 CT MFC SR- s (2.68 ± 1.74 months). SR were located axially in foals <7 months of age, and centrally thereafter. All SRs had areas of thickened cartilage on histology and separation at the osteochondral junction containing fibrin (acute event) and fibroplasia (chronicity) in 73.9% (17/23; 95% CI: 56%-91.9%). In Group 1 specimens, chondronecrosis was present in 82.6% (19/23; 95% CI: 67.1%-98.1%) but four MFC SR+ had no evidence of chondronecrosis. Chondronecrosis was not detected in the Group 3 foal MFCs. MAIN LIMITATIONS No longitudinal follow-up. CONCLUSIONS The absence of chondronecrosis, pathognomic of osteochondrosis, in four MFC SR+s and in all of the CT MFC SR- foals suggests that osteochondrosis is not the cause, or the only cause, of these lesions and favours trauma as an alternate aetiological hypothesis.
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Affiliation(s)
- Thibeaut Lemirre
- Comparative Orthopaedic Research Laboratory, Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, QC, Canada
| | | | - Christiane A Girard
- Comparative Orthopaedic Research Laboratory, Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, QC, Canada
| | | | - Jennifer G Janes
- Department of Veterinary Science, University of Kentucky, Lexington, KY, USA
| | - Helene Richard
- Comparative Orthopaedic Research Laboratory, Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, QC, Canada
| | - Sheila Laverty
- Comparative Orthopaedic Research Laboratory, Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, QC, Canada
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4
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D'Andrea CR, Alfraihat A, Singh A, Anari JB, Cahill PJ, Schaer T, Snyder BD, Elliott D, Balasubramanian S. Part 1. Review and meta-analysis of studies on modulation of longitudinal bone growth and growth plate activity: A macro-scale perspective. J Orthop Res 2021; 39:907-918. [PMID: 33377536 DOI: 10.1002/jor.24976] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/20/2020] [Accepted: 12/24/2020] [Indexed: 02/04/2023]
Abstract
Growth modulation is an emerging method for treatment of angular skeletal deformities such as adolescent idiopathic scoliosis (AIS). The Hueter-Volkmann law, by which growth is stimulated in tension and inhibited in compression, is widely understood, and applied in current growth-modulating interventions such as anterior vertebral body tethering (AVBT) for AIS. However, without quantification of the growth rate effects of tension or compression, the possibility of under- or over- correction exists. A definitive mechanical growth modulation relationship relating to treatment of such skeletal deformities is yet to exist, and the mechanisms by which growth rate is regulated and altered are not fully defined. Review of current literature demonstrates that longitudinal (i.e., lengthwise) growth rate in multiple animal models depend on load magnitude, anatomical location, and species. Additionally, alterations in growth plate morphology and viability vary by loading parameters such as magnitude, frequency, and whether the load was applied persistently or intermittently. The aggregate findings of the reviewed studies will assist in work towards increasingly precise and clinically successful growth modulation methods. Part 1 of this review focuses on the effects of mechanical loading, species, age, and anatomical location on the macro-scale alterations in longitudinal bone growth, as well as factors that affect growth plate material properties. Part 2 considers the effects on micro-scale alterations in growth plate morphology such as zone heights and proportions, chondrocyte viability, and related gene and protein expression.
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Affiliation(s)
- Christian R D'Andrea
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania, USA
| | - Ausilah Alfraihat
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania, USA
| | - Anita Singh
- Department of Biomedical Engineering, Widener University, Chester, Pennsylvania, USA
| | - Jason B Anari
- Division of Orthopaedics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Patrick J Cahill
- Division of Orthopaedics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Thomas Schaer
- Department of Clinical Studies New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
| | - Brian D Snyder
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Dawn Elliott
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware, USA
| | - Sriram Balasubramanian
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania, USA
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5
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Effect of Long-Term Diving on the Morphology and Growth of the Distal Radial Epiphyseal Plate of Young Divers: A Magnetic Resonance Imaging Study. Clin J Sport Med 2019; 29:312-317. [PMID: 31241534 DOI: 10.1097/jsm.0000000000000523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To investigate the effects of long-term diving on the morphology and growth of the distal radial epiphyseal plate in young divers. STUDY DESIGN Cohort study. SETTING Guangzhou Sport University. PARTICIPANTS Thirty-eight professional divers, aged 10 to 17 years, and 25 age-matched volunteers. INTERVENTIONS Each subject received a physical examination at the beginning of the study and underwent bilateral magnetic resonance imaging of the wrist. The divers were divided into 2 groups depending on the status of the epiphyseal plate: group A (positive distal radial epiphyseal plate injury) and group B (no positive distal radial epiphyseal plate injury). A third group, group C, consisted of the 25 volunteers. MAIN OUTCOME MEASURES The frequency of distal radial epiphyseal plate injury and the thickness of the distal radial epiphyseal plate were analyzed across the 3 groups. RESULTS Twenty-nine cases (29/76, 38.15%) of distal radial epiphyseal plate injury were observed in 20 divers (20/38, 52.63%). The incidence of injury to the right hand was higher than that for the left (P = 0.009). There were statistically significant differences (P = 0.000) among the 3 groups in terms of epiphyseal plate thickness; group A > group B > group C. CONCLUSIONS Distal radial epiphyseal plate injury is common in divers, and more injuries are seen in the right hand. Moreover, growth of the radius was impaired in divers relative to controls. We consider that loading during diving may influence growth of the epiphyseal plate in either a transient or permanent manner.
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6
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Huang L, Korhonen RK, Turunen MJ, Finnilä MAJ. Experimental mechanical strain measurement of tissues. PeerJ 2019; 7:e6545. [PMID: 30867989 PMCID: PMC6409087 DOI: 10.7717/peerj.6545] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 01/31/2019] [Indexed: 12/22/2022] Open
Abstract
Strain, an important biomechanical factor, occurs at different scales from molecules and cells to tissues and organs in physiological conditions. Under mechanical strain, the strength of tissues and their micro- and nanocomponents, the structure, proliferation, differentiation and apoptosis of cells and even the cytokines expressed by cells probably shift. Thus, the measurement of mechanical strain (i.e., relative displacement or deformation) is critical to understand functional changes in tissues, and to elucidate basic relationships between mechanical loading and tissue response. In the last decades, a great number of methods have been developed and applied to measure the deformations and mechanical strains in tissues comprising bone, tendon, ligament, muscle and brain as well as blood vessels. In this article, we have reviewed the mechanical strain measurement from six aspects: electro-based, light-based, ultrasound-based, magnetic resonance-based and computed tomography-based techniques, and the texture correlation-based image processing method. The review may help solving the problems of experimental and mechanical strain measurement of tissues under different measurement environments.
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Affiliation(s)
- Lingwei Huang
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Rami K Korhonen
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Mikael J Turunen
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Mikko A J Finnilä
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.,Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland.,Medical Research Center Oulu, Oulu University Hospital, Oulu, Finland
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7
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Vendra BB, Roan E, Williams JL. Chondron curvature mapping in growth plate cartilage under compressive loading. J Mech Behav Biomed Mater 2018; 84:168-177. [PMID: 29783204 DOI: 10.1016/j.jmbbm.2018.05.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 05/03/2018] [Accepted: 05/09/2018] [Indexed: 02/05/2023]
Abstract
The physis, or growth plate, is a layer of cartilage responsible for long bone growth. It is organized into reserve, proliferative and hypertrophic zones. Unlike the reserve zone where chondrocytes are randomly arranged, either singly or in pairs, the proliferative and hypertrophic chondrocytes are arranged within tubular structures called chondrons. In previous studies, the strain patterns within the compressed growth plate have been reported to be nonuniform and inhomogeneous, with an apparent random pattern in compressive strains and a localized appearance of tensile strains. In this study we measured structural deformations along the entire lengths of chondrons when the physis was subjected to physiological (20%) and hyper-physiological (30% and 40%) levels of compression. This provided a means to interpret the apparent random strain patterns seen in texture correlation maps in terms of bending deformations of chondron structures and provided a physical explanation for the inhomogeneous and nonuniform strain patterns reported in previous studies. We observed relatively large bending deformations (kinking) of the chondron structures at the interface of the reserve and proliferative zones during compression. Bending in this region may induce dividing cells to align longitudinally to maintain column formation and drive longitudinal growth.
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Affiliation(s)
- Bhavya B Vendra
- Department of Biomedical Engineering, University of Memphis, 330 Engineering Technology Building, Memphis, TN 38152, United States
| | - Esra Roan
- Department of Biomedical Engineering, University of Memphis, 330 Engineering Technology Building, Memphis, TN 38152, United States
| | - John L Williams
- Department of Biomedical Engineering, University of Memphis, 330 Engineering Technology Building, Memphis, TN 38152, United States.
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8
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Staines KA, Madi K, Javaheri B, Lee PD, Pitsillides AA. A Computed Microtomography Method for Understanding Epiphyseal Growth Plate Fusion. FRONTIERS IN MATERIALS 2018; 4:48. [PMID: 29417047 PMCID: PMC5798587 DOI: 10.3389/fmats.2017.00048] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The epiphyseal growth plate is a developmental region responsible for linear bone growth, in which chondrocytes undertake a tightly regulated series of biological processes. Concomitant with the cessation of growth and sexual maturation, the human growth plate undergoes progressive narrowing, and ultimately disappears. Despite the crucial role of this growth plate fusion "bridging" event, the precise mechanisms by which it is governed are complex and yet to be established. Progress is hindered by the current methods for growth plate visualization; these are invasive and largely rely on histological procedures. Here, we describe our non-invasive method utilizing synchrotron X-ray computed microtomography for the examination of growth plate bridging, which ultimately leads to its closure coincident with termination of further longitudinal bone growth. We then apply this method to a dataset obtained from a benchtop micro computed tomography scanner to highlight its potential for wide usage. Furthermore, we conduct finite element modeling at the micron-scale to reveal the effects of growth plate bridging on local tissue mechanics. Employment of these 3D analyses of growth plate bone bridging is likely to advance our understanding of the physiological mechanisms that control growth plate fusion.
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Affiliation(s)
- Katherine A. Staines
- School of Applied Sciences, Edinburgh Napier University, Edinburgh, United Kingdom
| | - Kamel Madi
- School of Materials, The University of Manchester, Manchester, United Kingdom
| | - Behzad Javaheri
- Comparative Biomedical Sciences, Royal Veterinary College, London, United Kingdom
| | - Peter D. Lee
- School of Materials, The University of Manchester, Manchester, United Kingdom
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9
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Abstract
The growth plate (physis) is responsible for enabling and regulating longitudinal growth of upper and lower limbs. This regulation occurs through interaction of the cells in the growth plate with systemic and locally produced factors. This complex interaction leads to precisely controlled changes in chondrocyte size, receptors, and matrix, which ultimately result in endochondral bone formation. With advances in cellular and molecular biology, our knowledge about these complex interactions has increased significantly over the past decade. Deficiency of any of the regulating factors or physeal injury during childhood can alter this well-orchestrated sequence of events and lead to abnormalities in growth. This review highlights the histology of the normal physis, including recent findings at the cellular and molecular levels, mechanics and mechanobiology of the growth plate, pathologies that can affect the physis, and treatment options, including interposition materials.
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10
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Prein C, Warmbold N, Farkas Z, Schieker M, Aszodi A, Clausen-Schaumann H. Structural and mechanical properties of the proliferative zone of the developing murine growth plate cartilage assessed by atomic force microscopy. Matrix Biol 2016; 50:1-15. [DOI: 10.1016/j.matbio.2015.10.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 09/25/2015] [Accepted: 10/06/2015] [Indexed: 12/13/2022]
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11
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Verbruggen SW, Mc Garrigle MJ, Haugh MG, Voisin MC, McNamara LM. Altered mechanical environment of bone cells in an animal model of short- and long-term osteoporosis. Biophys J 2016; 108:1587-1598. [PMID: 25863050 DOI: 10.1016/j.bpj.2015.02.031] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 01/28/2015] [Accepted: 02/03/2015] [Indexed: 01/18/2023] Open
Abstract
Alterations in bone tissue composition during osteoporosis likely disrupt the mechanical environment of bone cells and may thereby initiate a mechanobiological response. It has proved challenging to characterize the mechanical environment of bone cells in vivo, and the mechanical environment of osteoporotic bone cells is not known. The objective of this research is to characterize the local mechanical environment of osteocytes and osteoblasts from healthy and osteoporotic bone in a rat model of osteoporosis. Using a custom-designed micromechanical loading device, we apply strains representative of a range of physical activity (up to 3000 με) to fluorescently stained femur samples from normal and ovariectomized rats. Confocal imaging was simultaneously performed, and digital image correlation techniques were applied to characterize cellular strains. In healthy bone tissue, osteocytes experience higher maximum strains (31,028 ± 4213 με) than osteoblasts (24,921 ± 3,832 με), whereas a larger proportion of the osteoblast experiences strains >10,000 με. Most interestingly, we show that osteoporotic bone cells experience similar or higher maximum strains than healthy bone cells after short durations of estrogen deficiency (5 weeks), and exceeded the osteogenic strain threshold (10,000 με) in a similar or significantly larger proportion of the cell (osteoblast, 12.68% vs. 13.68%; osteocyte, 15.74% vs. 5.37%). However, in long-term estrogen deficiency (34 weeks), there was no significant difference between bone cells in healthy and osteoporotic bone. These results suggest that the mechanical environment of bone cells is altered during early-stage osteoporosis, and that mechanobiological responses act to restore the mechanical environment of the bone tissue after it has been perturbed by ovariectomy.
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Affiliation(s)
- Stefaan W Verbruggen
- Biomechanics Research Centre, National Centre for Biomedical Engineering Science, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - Myles J Mc Garrigle
- Biomechanics Research Centre, National Centre for Biomedical Engineering Science, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - Matthew G Haugh
- Biomechanics Research Centre, National Centre for Biomedical Engineering Science, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - Muriel C Voisin
- Biomechanics Research Centre, National Centre for Biomedical Engineering Science, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland
| | - Laoise M McNamara
- Biomechanics Research Centre, National Centre for Biomedical Engineering Science, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland.
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12
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Kaviani R, Londono I, Parent S, Moldovan F, Villemure I. Compressive mechanical modulation alters the viability of growth plate chondrocytes in vitro. J Orthop Res 2015; 33:1587-93. [PMID: 26019113 DOI: 10.1002/jor.22951] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 05/25/2015] [Indexed: 02/04/2023]
Abstract
The aim of this study was to investigate the effect of compressive modulation parameters (mode, magnitude, duration, as well as frequency and amplitude for cyclic modulation) on the viability of growth plate chondrocytes. Swine ulnar growth plate explants (n = 60) were randomly distributed among 10 groups: baseline (n = 1 × 6); culture control (n = 1 × 6); static (n = 3 × 6); and dynamic (n = 5 × 6). Static and dynamic samples were modulated in vitro using a bioreactor. Different compression magnitudes (0.1 MPa or 0.2 MPa), durations (12 h or 24 h), frequencies (0.1 Hz or 1.0 Hz), and amplitudes (30% or 100%) were investigated. Viability was assessed by automatic quantification of number of live/dead cells from confocal images of Live/Dead labeled tissues. Chondrocyte viability was found to be dependent on compression magnitude, duration, frequency, and amplitude in a way that increasing each parameter decreased viability in certain zones of growth plate. More specifically, proliferative and hypertrophic chondrocytes were found to be more sensitive to the applied compression. This study provides an in vitro protocol for studying the effects of compressive modulation on biomechanical and biological responses of growth plate explants, which will be useful in finding efficient and non-detrimental parameters for mechanical modulation of bone growth exploited in scoliosis fusionless treatments.
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Affiliation(s)
- Rosa Kaviani
- Mechanical Engineering Department, Biomedical Engineering Institute, Ecole Polytechnique of Montreal, Montreal, Quebec, Canada.,Sainte-Justine University Hospital Center, Montreal, Quebec, Canada
| | - Irene Londono
- Sainte-Justine University Hospital Center, Montreal, Quebec, Canada
| | - Stefan Parent
- Sainte-Justine University Hospital Center, Montreal, Quebec, Canada.,Department of Surgery, University of Montreal, Montreal, Quebec, Canada
| | - Florina Moldovan
- Sainte-Justine University Hospital Center, Montreal, Quebec, Canada.,Department of Stomatology, University of Montreal, Montreal, Canada
| | - Isabelle Villemure
- Mechanical Engineering Department, Biomedical Engineering Institute, Ecole Polytechnique of Montreal, Montreal, Quebec, Canada.,Sainte-Justine University Hospital Center, Montreal, Quebec, Canada
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13
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Growth plate cartilage shows different strain patterns in response to static versus dynamic mechanical modulation. Biomech Model Mechanobiol 2015; 15:933-46. [DOI: 10.1007/s10237-015-0733-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 09/29/2015] [Indexed: 10/22/2022]
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14
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Gao J, Roan E, Williams JL. Regional variations in growth plate chondrocyte deformation as predicted by three-dimensional multi-scale simulations. PLoS One 2015; 10:e0124862. [PMID: 25885547 PMCID: PMC4401775 DOI: 10.1371/journal.pone.0124862] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 03/10/2015] [Indexed: 11/17/2022] Open
Abstract
The physis, or growth plate, is a complex disc-shaped cartilage structure that is responsible for longitudinal bone growth. In this study, a multi-scale computational approach was undertaken to better understand how physiological loads are experienced by chondrocytes embedded inside chondrons when subjected to moderate strain under instantaneous compressive loading of the growth plate. Models of representative samples of compressed bone/growth-plate/bone from a 0.67 mm thick 4-month old bovine proximal tibial physis were subjected to a prescribed displacement equal to 20% of the growth plate thickness. At the macroscale level, the applied compressive deformation resulted in an overall compressive strain across the proliferative-hypertrophic zone of 17%. The microscale model predicted that chondrocytes sustained compressive height strains of 12% and 6% in the proliferative and hypertrophic zones, respectively, in the interior regions of the plate. This pattern was reversed within the outer 300 μm region at the free surface where cells were compressed by 10% in the proliferative and 26% in the hypertrophic zones, in agreement with experimental observations. This work provides a new approach to study growth plate behavior under compression and illustrates the need for combining computational and experimental methods to better understand the chondrocyte mechanics in the growth plate cartilage. While the current model is relevant to fast dynamic events, such as heel strike in walking, we believe this approach provides new insight into the mechanical factors that regulate bone growth at the cell level and provides a basis for developing models to help interpret experimental results at varying time scales.
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Affiliation(s)
- Jie Gao
- Departments of Mechanical Engineering, University of Memphis Memphis, Tennessee, 38152, United States of America
| | - Esra Roan
- Department of Biomedical Engineering, University of Memphis Memphis, Tennessee, 38152, United States of America
| | - John L Williams
- Department of Biomedical Engineering, University of Memphis Memphis, Tennessee, 38152, United States of America
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15
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Mauri A, Ehret AE, Perrini M, Maake C, Ochsenbein-Kölble N, Ehrbar M, Oyen ML, Mazza E. Deformation mechanisms of human amnion: Quantitative studies based on second harmonic generation microscopy. J Biomech 2015; 48:1606-13. [PMID: 25805698 DOI: 10.1016/j.jbiomech.2015.01.045] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 01/31/2015] [Indexed: 11/15/2022]
Abstract
Multiphoton microscopy has proven to be a versatile tool to analyze the three-dimensional microstructure of the fetal membrane and the mechanisms of deformation on the length scale of cells and the collagen network. In the present contribution, dedicated microscopic tools for in situ mechanical characterization of tissue under applied mechanical loads and the related methods for data interpretation are presented with emphasis on new stepwise monotonic uniaxial experiments. The resulting microscopic parameters are consistent with previous ones quantified for cyclic and relaxation tests, underlining the reliability of these techniques. The thickness reduction and the substantial alignment of collagen fiber bundles in the compact and fibroblast layer starting at very small loads are highlighted, which challenges the definition of a reference configuration in terms of a force threshold. The findings presented in this paper intend to inform the development of models towards a better understanding of fetal membrane deformation and failure, and thus of related problems in obstetrics and other clinical conditions.
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Affiliation(s)
- Arabella Mauri
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland.
| | - Alexander E Ehret
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Michela Perrini
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland; Department of Obstetrics, University Hospital Zürich, 8091 Zurich, Switzerland
| | - Caroline Maake
- Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland
| | | | - Martin Ehrbar
- Department of Obstetrics, University Hospital Zürich, 8091 Zurich, Switzerland
| | - Michelle L Oyen
- Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ, UK
| | - Edoardo Mazza
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland; Swiss Federal Laboratories for Materials Science and Technology, EMPA, 8600 Dübendorf, Switzerland
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Li J, Johnson CA, Smith AA, Shi B, Brunski JB, Helms JA. Molecular mechanisms underlying skeletal growth arrest by cutaneous scarring. Bone 2014; 66:223-31. [PMID: 24933346 DOI: 10.1016/j.bone.2014.06.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 03/11/2014] [Accepted: 06/03/2014] [Indexed: 02/06/2023]
Abstract
In pediatric surgeries, cutaneous scarring is frequently accompanied by an arrest in skeletal growth. The molecular mechanisms responsible for this effect are not understood. Here, we investigated the relationship between scar contracture and osteogenesis. An excisional cutaneous wound was made on the tail of neonatal mice. Finite element (FE) modeling of the wound site was used to predict the distribution and magnitude of contractile forces within soft and hard tissues. Morphogenesis of the bony vertebrae was monitored by micro-CT analyses, and vertebral growth plates were interrogated throughout the healing period using assays for cell proliferation, death, differentiation, as well as matrix deposition and remodeling. Wound contracture was grossly evident on post-injury day 7 and accompanying it was a significant shortening in the tail. FE modeling indicated high compressive strains localized to the dorsal portions of the vertebral growth plates and intervertebral disks. These predicted strain distributions corresponded to sites of increased cell death, a cessation in cell proliferation, and a loss in mineralization within the growth plates and IVD. Although cutaneous contracture resolved and skeletal growth rates returned to normal, vertebrae under the cutaneous wound remained significantly shorter than controls. Thus, localized contractile forces generated by scarring led to spatial alterations in cell proliferation, death, and differentiation that inhibited bone growth in a location-dependent manner. Resolution of cutaneous scarring was not accompanied by compensatory bone growth, which left the bony elements permanently truncated. Therefore, targeting early scar reduction is critical to preserving pediatric bone growth after surgery.
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Affiliation(s)
- Jingtao Li
- Department of Oral and Maxillofacial Surgery, West China Stomatology Hospital, Chengdu 610041, China; Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford CA 94035, USA
| | - Chelsey A Johnson
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford CA 94035, USA; College of Medicine, University of Arizona, Tucson, AZ 85719, USA
| | - Andrew A Smith
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford CA 94035, USA
| | - Bing Shi
- Department of Oral and Maxillofacial Surgery, West China Stomatology Hospital, Chengdu 610041, China
| | - John B Brunski
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford CA 94035, USA
| | - Jill A Helms
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford School of Medicine, Stanford CA 94035, USA.
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Multi-scale finite element model of growth plate damage during the development of slipped capital femoral epiphysis. Biomech Model Mechanobiol 2014; 14:371-85. [DOI: 10.1007/s10237-014-0610-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 08/04/2014] [Indexed: 10/24/2022]
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Celarek A, Fischerauer SF, Weinberg AM, Tschegg EK. Fracture patterns of the growth plate and surrounding bone in the ovine knee joint at different ages. J Mech Behav Biomed Mater 2013; 29:286-94. [PMID: 24126101 DOI: 10.1016/j.jmbbm.2013.09.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 09/04/2013] [Accepted: 09/06/2013] [Indexed: 10/26/2022]
Abstract
Fractures of the growth plate region were performed with cadaver specimens obtained from the ovine distal femur and proximal tibia. Specimens of 6 different ages, ranging from 1 week to 4 years, were investigated in order to determine changes in the fracture characteristics. Mechanical properties (crack resistance and notch tensile strength), supported by microscopy of the distal tibia (thickness of growth plate and its zones, trabecular bone volume ratio) were determined. The crack propagated through different regions depending on age, which was observed both in microscopy and mechanical tests. In specimens of younger animals the fracture typically went through trabecular bone, often parallel to the growth plate, and only sometimes through the growth plate cartilage. Specimens of older animals fractured directly through the growth plate cartilage, while trabecular bone was not affected at all. Adult specimens had significantly higher mechanical values than the young ones. The results reveal the underlying mechanical properties that induce different fracture patterns of the epiphyseal growth plate at different stages of growth. The possibility of fractures through trabecular bone parallel to the growth plate in newborns and infants should be considered when clinical radiographs of paediatric fractures are analysed and classified.
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Affiliation(s)
- A Celarek
- Institute for Building Construction and Technology E-206-4, Vienna University of Technology, Karlsplatz 13, A-1040 Vienna, Austria.
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Sevenler D, Buckley MR, Kim G, van der Meulen MCH, Cohen I, Bonassar LJ. Spatial periodicity in growth plate shear mechanical properties is disrupted by vitamin D deficiency. J Biomech 2013; 46:1597-603. [PMID: 23706979 DOI: 10.1016/j.jbiomech.2013.04.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 04/17/2013] [Accepted: 04/23/2013] [Indexed: 12/01/2022]
Abstract
The growth plate is a highly organized section of cartilage in the long bones of growing children that is susceptible to mechanical failure as well as structural and functional disruption caused by a dietary deficiency of vitamin D. The shear mechanical properties of the proximal tibial growth plate of rats raised either on normal or vitamin D and calcium deficient diets were measured. A sinusoidal oscillating shear load was applied to small excised growth plate specimens perpendicular to the direction of growth while imaging the deformation in real time with a fast confocal microscope. Local deformations and shear strains were quantified using image correlation. The proliferative zone of the growth plate bores the majority of the shear strain and the resting, hypertrophic and calcification zones deformed less. Surprisingly, we regularly observed discontinuous deformations in the proliferative zone in both groups that resembled cell columns sliding past one another in the direction of growth. These discontinuities manifested as regions of concentrated longitudinal shear strain. Furthermore, these shear strain concentrations were spaced evenly in the proliferative zone and the spacing between them was similar across growth plate regions and across control specimens. In contrast to the healthy controls, the vitamin D deficient growth plate exhibited larger variations in the size and orientation of cellular columns in the proliferative and hypertrophic zones. High strains were observed between columns, much as they were in the controls. However, the regular spacing of shear strain concentrations was not preserved, echoing the observation of decreased structural organization.
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Affiliation(s)
- Derin Sevenler
- Sibley School of Mechanical & Aerospace Engineering, Cornell University, Ithaca, NY, USA.
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Physeal cartilage exhibits rapid consolidation and recovery in intact knees that are physiologically loaded. J Biomech 2013; 46:1516-23. [DOI: 10.1016/j.jbiomech.2013.03.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 03/23/2013] [Accepted: 03/30/2013] [Indexed: 11/20/2022]
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21
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Tschegg E, Celarek A, Fischerauer S, Stanzl-Tschegg S, Weinberg A. Fracture properties of growth plate cartilage compared to cortical and trabecular bone in ovine femora. J Mech Behav Biomed Mater 2012; 14:119-29. [DOI: 10.1016/j.jmbbm.2012.05.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 05/14/2012] [Accepted: 05/20/2012] [Indexed: 10/28/2022]
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Hardisty MR, Akens MK, Hojjat SP, Yee A, Whyne CM. Quantification of the effect of osteolytic metastases on bone strain within whole vertebrae using image registration. J Orthop Res 2012; 30:1032-9. [PMID: 22213180 DOI: 10.1002/jor.22045] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 11/29/2011] [Indexed: 02/04/2023]
Abstract
The vertebral column is the most frequent site of metastatic involvement of the skeleton with up to 1/3 of all cancer patients developing spinal metastases. Longer survival times for patients, particularly secondary to breast cancer, have increased the need for better understanding the impact of skeletal metastases on structural stability. This study aims to apply image registration to calculate strain distributions in metastatically involved rodent vertebrae utilizing µCT imaging. Osteolytic vertebral lesions were developed in five rnu/rnu rats 2-3 weeks post intracardiac injection with MT-1 human breast cancer cells. An image registration algorithm was used to calculate and compare strain fields due to axial compressive loading in metastatically involved and control vertebrae. Tumor-bearing vertebrae had greatly increased compressive strains, double the magnitude of strain compared to control vertebrae (p=0.01). Qualitatively strain concentrated within the growth plates in both tumor bearing and control vertebrae. Most interesting was the presence of strain concentrations at the dorsal wall in metastatically involved vertebrae, suggesting structural instability. Strain distributions, quantified by image registration were consistent with known consequences of lytic involvement. Metastatically involved vertebrae had greater strain magnitude than control vertebrae. Strain concentrations at the dorsal wall in only the metastatic vertebrae, were consistent with higher incidence of burst fracture secondary to this pathology. Future use of image registration of whole vertebrae will allow focused examination of the efficacy of targeted and systemic treatments in reducing strains and the related risk of fracture in pathologic bones under simple and complex loading.
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Affiliation(s)
- Michael R Hardisty
- Orthopaedic Biomechanics Laboratory, Sunnybrook Health Sciences Centre, 2075 Bayview Ave., Room UB-19, University of Toronto, Toronto, Ontario, Canada
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Amini S, Mortazavi F, Sun J, Levesque M, Hoemann CD, Villemure I. Stress relaxation of swine growth plate in semi-confined compression: depth dependent tissue deformational behavior versus extracellular matrix composition and collagen fiber organization. Biomech Model Mechanobiol 2012; 12:67-78. [DOI: 10.1007/s10237-012-0382-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 02/22/2012] [Indexed: 02/08/2023]
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Peng Q, Wang Y, Qiu J, Zhang B, Sun J, Lv Y, Yang L. A novel mechanical loading model for studying the distributions of strain and mechano-growth factor expression. Arch Biochem Biophys 2011; 511:8-13. [DOI: 10.1016/j.abb.2011.04.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 04/19/2011] [Accepted: 04/22/2011] [Indexed: 01/06/2023]
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Wosu R, Sergerie K, Lévesque M, Villemure I. Mechanical properties of the porcine growth plate vary with developmental stage. Biomech Model Mechanobiol 2011; 11:303-12. [DOI: 10.1007/s10237-011-0310-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 04/21/2011] [Indexed: 10/18/2022]
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26
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Amini S, Veilleux D, Villemure I. Tissue and cellular morphological changes in growth plate explants under compression. J Biomech 2011; 43:2582-8. [PMID: 20627250 DOI: 10.1016/j.jbiomech.2010.05.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 04/23/2010] [Accepted: 05/11/2010] [Indexed: 11/29/2022]
Abstract
The mechanisms by which mechanical loading may alter bone development within growth plates are still poorly understood. However, several growth plate cell or tissue morphological parameters are associated with both normal and mechanically modulated bone growth rates. The aim of this study was to quantify in situ the three-dimensional morphology of growth plate explants under compression at both cell and tissue levels. Growth plates were dissected from ulnae of immature swine and tested under 15% compressive strain. Confocal microscopy was used to image fluorescently labeled chondrocytes in the three growth plate zones before and after compression. Quantitative morphological analyses at both cell (volume, surface area, sphericity, minor/major radii) and tissue (cell/matrix volume ratio) levels were performed. Greater chondrocyte bulk strains (volume decrease normalized to the initial cell volume) were found in the proliferative (35.4%) and hypertrophic (41.7%) zones, with lower chondrocyte bulk strains (24.7%) in the reserve zone. Following compression, the cell/matrix volume ratio decreased in the reserve and hypertrophic zones by 24.3% and 22.6%, respectively, whereas it increased by 35.9% in the proliferative zone. The 15% strain applied on growth plate explants revealed zone-dependent deformational states at both tissue and cell levels. Variations in the mechanical response of the chondrocytes from different zones could be related to significant inhomogeneities in growth plate zonal mechanical properties. The ability to obtain in situ cell morphometry and monitor the changes under compression will contribute to a better understanding of mechanisms through which abnormal growth can be triggered.
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Affiliation(s)
- Samira Amini
- Department of Mechanical Engineering, Ecole Polytechnique of Montreal, Station Centre-Ville, Montréal, Québec, Canada.
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27
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Abstract
STUDY DESIGN A biomechanical study of the Charleston brace. OBJECTIVE To model the nighttime Charleston brace treatment and study its biomechanical action. SUMMARY OF BACKGROUND DATA The Charleston brace has been proposed as an alternative to the traditional daytime thoracolumbosacral orthosis for the treatment of moderate scoliotic deformities. It is worn at night and imposes a supine side-bending to reduce the major scoliotic curve. The biomechanics of the Charleston brace is still poorly understood. METHODS The geometry of the spine, pelvis, rib cage, and of the external trunk surface of 2 scoliotic patients were acquired using a 3-dimensional multiview radiograph reconstruction technique and surface topography. A finite element model of each patient's trunk was created. Two sets of mechanical properties (stiff and normal) of the spine were tested. For each case, the transition from standing to supine position was first simulated by modifying the direction of the gravity forces acting on the patients' spine. Supine bending was simulated by applying a lateral displacement on the first thoracic vertebra. A custom-fit Charleston brace was modeled and positioned on the patient model. Tension was applied in the straps. Efficiency of the simulated Charleston braces was studied by computing geometrical corrections and effects on the internal stresses of the spine. RESULTS The reduction of the major scoliotic curve varied between 58% and 97% and was in the range of published clinical data. Internal compressive stresses up to 1 MPa were generated on the convex side of the major scoliotic curve and tensile stresses up to 1 MPa on its concavity. In contrast, increased compressive stresses were exerted on the concavity of the secondary curves and added tensile stresses in their convexity. CONCLUSION This study quantified the Charleston brace's biomechanical effect, which consists in inverting the asymmetrical compressive loading in the major scoliotic curve. It also highlighted that the Charleston brace worsens the asymmetrical compressive loading in the compensatory curves. The finite element model developed could help studying different brace designs and optimizing brace efficiency.
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Hardisty MR, Akens M, Yee AJ, Whyne CM. Image registration demonstrates the growth plate has a variable affect on vertebral strain. Ann Biomed Eng 2010; 38:2948-55. [PMID: 20443059 DOI: 10.1007/s10439-010-0052-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Accepted: 04/16/2010] [Indexed: 11/25/2022]
Abstract
Characterizing the biomechanical behavior of the vertebrae is important in understanding the impact of structural and material changes on spinal growth and fracture risk. The growth plate is critical for the normal development of the skeleton, with abnormalities leading to uneven maturation. Little is known about how growth plates affect the stress and strain experienced by the surrounding bone. Concentrated strain within the growth plate may influence mechanical cell signaling during development, lead to increased fracture risk at this site and may influence average bone strain measures. It is hypothesized that the growth plates and adjacent bony areas will take up a large amount of the strain within rat-tail vertebrae under axial compressive loading, leading to increased average bone strain measures. The sixth caudal vertebrae of 8 rnu/rnu rats were muCT scanned in both loaded (20-32 N axial compression) and unloaded configurations. Image registration was used to calculate strain in the bone due to the applied load by finding a spatial mapping between the two scans. In seven of the eight rats, the majority of the strain measured within their vertebrae was concentrated in the growth plates. Five of the specimens had growth plates that demonstrated rigid behavior in contrast to compliant growth plate behavior seen in the other three rats. The presence of a compliant growth plate led to higher average (-0.03 vs. -0.01) and maximum (-0.13 vs. -0.02) strains. The strain within the growth plate is important to consider when interpreting apparent tissue level biomechanical data commonly reported in the literature as this study suggests strains are not uniformly distributed with high concentrations in and around the growth plate. This strain distribution may provide insight into the mechanical signals that cells experience during the formation of new bone, with the higher strains near the growth plate signaling cells to lay down more bone, while also leading to increased risk of fracture in this region.
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Affiliation(s)
- M R Hardisty
- Sunnybrook Health Sciences Centre, University of Toronto, ON, Canada
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Chen J, Lee CSD, Coleman RM, Yoon JY, Lohmann CH, Zustin J, Guldberg RE, Schwartz Z, Boyan BD. Formation of tethers linking the epiphysis and metaphysis is regulated by vitamin d receptor-mediated signaling. Calcif Tissue Int 2009; 85:134-45. [PMID: 19506934 DOI: 10.1007/s00223-009-9259-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2009] [Accepted: 04/30/2009] [Indexed: 10/20/2022]
Abstract
Rat tibial growth plates have X-ray opaque tethers that link the epiphysis and metaphysis and increase with age as the growth plate (GP) becomes thinner. To determine if tether formation is a regulated process of GP maturation, we tested the hypotheses that tether properties and distribution can be quantified by micro-computed tomography (microCT), that rachitic GPs typical of vitamin D receptor knockout (VDR(-/-)) mice have fewer tethers and altered tether distribution, and that tether formation is regulated by signaling via the VDR. Distal femoral GPs from VDR(+/+) and VDR(-/-) 8-week-old mice were analyzed with microCT and then processed for decalcified and undecalcified histomorphometry. A wide range of parameters that assessed GP and tether geometry and morphology, along with tether distribution, were measured using both microCT and histology. Growth plates of 10-week-old VDR(+/+) and VDR(-/-) mice on a high-calcium, phosphorus, lactose, and vitamin D(3) rescue diet were also analyzed. Both microCT and histology showed tethers present throughout normal mice GPs, while reduction in tether number and volume percentage occurred in VDR(-/-) GPs with localization to the central region. Decreased shrinkage in the axial direction during decalcified histological processing correlated with tether formation, suggesting mechanical stability due to tethers. Tether formation increased greatly between 8 and 10 weeks. Rescue diets restored VDR(-/-) GP size but not tether volume percentage. Overall, these results demonstrate microCT imaging's utility for analyzing tether formation and suggest that signaling via the VDR plays a pivotal role in tether formation.
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Affiliation(s)
- Jida Chen
- Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332-0363, USA
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Villemure I, Stokes IAF. Growth plate mechanics and mechanobiology. A survey of present understanding. J Biomech 2009; 42:1793-803. [PMID: 19540500 DOI: 10.1016/j.jbiomech.2009.05.021] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 04/14/2009] [Accepted: 05/08/2009] [Indexed: 10/20/2022]
Abstract
The longitudinal growth of long bones occurs in growth plates where chondrocytes synthesize cartilage that is subsequently ossified. Altered growth and subsequent deformity resulting from abnormal mechanical loading is often referred to as mechanical modulation of bone growth. This phenomenon has key implications in the progression of infant and juvenile musculoskeletal deformities, such as adolescent idiopathic scoliosis, hyperkyphosis, genu varus/valgus and tibia vara/valga, as well as neuromuscular diseases. Clinical management of these deformities is often directed at modifying the mechanical environment of affected bones. However, there is limited quantitative and physiological understanding of how bone growth is regulated in response to mechanical loading. This review of published work addresses the state of knowledge concerning key questions about mechanisms underlying biomechanical modulation of bone growth. The longitudinal growth of bones is apparently controlled by modifying the numbers of growth plate chondrocytes in the proliferative zone, their rate of proliferation, the amount of chondrocytic hypertrophy and the controlled synthesis and degradation of matrix throughout the growth plate. These variables may be modulated to produce a change in growth rate in the presence of sustained or cyclic mechanical load. Tissue and cellular deformations involved in the transduction of mechanical stimuli depend on the growth plate tissue material properties that are highly anisotropic, time-dependent, and that differ in different zones of the growth plate and with developmental stages. There is little information about the effects of time-varying changes in volume, water content, osmolarity of matrix, etc. on differentiation, maturation and metabolic activity of chondrocytes. Also, the effects of shear forces and torsion on the growth plate are incompletely characterized. Future work on growth plate mechanobiology should distinguish between changes in the regulation of bone growth resulting from different processes, such as direct stimulation of the cell nuclei, physico-chemical stimuli, mechanical degradation of matrix or cellular components and possible alterations of local blood supply.
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Affiliation(s)
- Isabelle Villemure
- Department of Mechanical Engineering, Ecole Polytechnique of Montreal, Station Centre-Ville, Montréal, Québec, Canada.
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31
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Mechanical properties of the porcine growth plate and its three zones from unconfined compression tests. J Biomech 2009; 42:510-6. [DOI: 10.1016/j.jbiomech.2008.11.026] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 11/07/2008] [Accepted: 11/10/2008] [Indexed: 11/24/2022]
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Sylvestre PL, Villemure I, Aubin CE. Finite element modeling of the growth plate in a detailed spine model. Med Biol Eng Comput 2007; 45:977-88. [PMID: 17687580 DOI: 10.1007/s11517-007-0220-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Accepted: 06/11/2007] [Indexed: 11/28/2022]
Abstract
Very few computer models of the spine integrate vertebral growth plates to investigate their mechanical behavior and potential impacts on bone growth. An approach was developed to generate a finite element (FE) model of the lumbar spine and their connective tissues including the growth plate, which allowed a personalization of the geometry based on patients' bi-planar radiographs. The geometrical validation was performed by deforming meshed vertebrae to reference vertebral specimens and comparing geometrical indices. No significant difference was found between the measured parameters, with errors under 1% in 83% of the geometrical parameters. Mechanical validation was done by simulating loading cases on a functional unit representing experimental testing on cadaveric spines. The flexibility of the functional unit remained between expected ranges of motion, but was more linear than experimental data. The mechanical behavior of the growth plate was evaluated under various loading cases: greater stresses were located in the proliferative zone for the different spinal loading cases tested. This modeling approach is a useful tool to study the effect of mechanical stresses on bone growth.
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Affiliation(s)
- Pierre-Luc Sylvestre
- Department of Mechanical Engineering, Ecole Polytechnique of Montreal, Station Centre-Ville, PO Box 6079, Montreal, QC, Canada H3C 3A7
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Phatak NS, Sun Q, Kim SE, Parker DL, Sanders RK, Veress AI, Ellis BJ, Weiss JA. Noninvasive determination of ligament strain with deformable image registration. Ann Biomed Eng 2007; 35:1175-87. [PMID: 17394084 DOI: 10.1007/s10439-007-9287-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Accepted: 02/26/2007] [Indexed: 11/24/2022]
Abstract
Ligament function and propensity for injury are directly related to regional stresses and strains. However, noninvasive techniques for measurement of strain are currently limited. This study validated the use of Hyperelastic Warping, a deformable image registration technique, for noninvasive strain measurement in the human medial collateral ligament using direct comparisons with optical measurements. Hyperelastic Warping determines the deformation map that aligns consecutive images of a deforming material, allowing calculation of strain. Diffeomorphic deformations are ensured by representing the deformable image as a hyperelastic material. Ten cadaveric knees were subjected to six loading scenarios each. Tissue deformation was documented with magnetic resonance imaging (MRI) and video-based experimental measurements. MRI datasets were analyzed using Hyperelastic Warping, representing the medial collateral ligament (MCL) with a hexahedral finite element (FE) model projected to a manually segmented ligament surface. The material behavior was transversely isotropic hyperelastic. Warping predictions of fiber stretch were strongly correlated with experimentally measured strains (R (2) = 0.81). Both sets of measurements were in agreement with previous ex vivo studies. Warping predictions of fiber stretch were insensitive to bulk:shear modulus ratio, fiber stiffness, and shear modulus in the range of +2.5SD to -1.0SD. Correlations degraded when the shear modulus was decreased to 2.5SD below the mean (R (2) = 0.56), and when an isotropic constitutive model was substituted for the transversely isotropic model (R (2) = 0.65). MCL strains in the transitional region near the joint line, where the material behavior and material symmetry are more complex, showed the most sensitivity to changes in shear modulus. These results demonstrate that Hyperelastic Warping requires the use of a constitutive model that reflects the material symmetry, but not subject-specific material properties for accurate strain predictions for this application. Hyperelastic Warping represents a powerful technique for noninvasive strain measurement of musculoskeletal tissues and has many advantages over other image-based strain measurement techniques.
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Affiliation(s)
- Nikhil S Phatak
- Department of Bioengineering, University of Utah, 50 S. Central Campus Drive, Rm. 2480, Salt Lake City, UT 84112, USA
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