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Griesbach JK, Schulte FA, Schädli GN, Rubert M, Müller R. Mechanoregulation analysis of bone formation in tissue engineered constructs requires a volumetric method using time-lapsed micro-computed tomography. Acta Biomater 2024; 179:149-163. [PMID: 38492908 DOI: 10.1016/j.actbio.2024.03.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 02/09/2024] [Accepted: 03/07/2024] [Indexed: 03/18/2024]
Abstract
Bone can adapt its microstructure to mechanical loads through mechanoregulation of the (re)modeling process. This process has been investigated in vivo using time-lapsed micro-computed tomography (micro-CT) and micro-finite element (FE) analysis using surface-based methods, which are highly influenced by surface curvature. Consequently, when trying to investigate mechanoregulation in tissue engineered bone constructs, their concave surfaces make the detection of mechanoregulation impossible when using surface-based methods. In this study, we aimed at developing and applying a volumetric method to non-invasively quantify mechanoregulation of bone formation in tissue engineered bone constructs using micro-CT images and FE analysis. We first investigated hydroxyapatite scaffolds seeded with human mesenchymal stem cells that were incubated over 8 weeks with one mechanically loaded and one control group. Higher mechanoregulation of bone formation was measured in loaded samples with an area under the curve for the receiver operating curve (AUCformation) of 0.633-0.637 compared to non-loaded controls (AUCformation: 0.592-0.604) during culture in osteogenic medium (p < 0.05). Furthermore, we applied the method to an in vivo mouse study investigating the effect of loading frequencies on bone adaptation. The volumetric method detected differences in mechanoregulation of bone formation between loading conditions (p < 0.05). Mechanoregulation in bone formation was more pronounced (AUCformation: 0.609-0.642) compared to the surface-based method (AUCformation: 0.565-0.569, p < 0.05). Our results show that mechanoregulation of formation in bone tissue engineered constructs takes place and its extent can be quantified with a volumetric mechanoregulation method using time-lapsed micro-CT and FE analysis. STATEMENT OF SIGNIFICANCE: Many efforts have been directed towards optimizing bone scaffolds for tissue growth. However, the impact of the scaffolds mechanical environment on bone growth is still poorly understood, requiring accurate assessment of its mechanoregulation. Existing surface-based methods were unable to detect mechanoregulation in tissue engineered constructs, due to predominantly concave surfaces in scaffolds. We present a volumetric approach to enable the precise and non-invasive quantification and analysis of mechanoregulation in bone tissue engineered constructs by leveraging time-lapsed micro-CT imaging, image registration, and finite element analysis. The implications of this research extend to diverse experimental setups, encompassing culture conditions, and material optimization, and investigations into bone diseases, enabling a significant stride towards comprehensive advancements in bone tissue engineering and regenerative medicine.
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Affiliation(s)
- Julia K Griesbach
- Institute for Biomechanics, ETH Zürich, Gloriastrasse 37/39, 8092 Zürich, Switzerland
| | - Friederike A Schulte
- Institute for Biomechanics, ETH Zürich, Gloriastrasse 37/39, 8092 Zürich, Switzerland
| | - Gian Nutal Schädli
- Institute for Biomechanics, ETH Zürich, Gloriastrasse 37/39, 8092 Zürich, Switzerland
| | - Marina Rubert
- Institute for Biomechanics, ETH Zürich, Gloriastrasse 37/39, 8092 Zürich, Switzerland
| | - Ralph Müller
- Institute for Biomechanics, ETH Zürich, Gloriastrasse 37/39, 8092 Zürich, Switzerland.
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2
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Walle M, Whittier DE, Schenk D, Atkins PR, Blauth M, Zysset P, Lippuner K, Müller R, Collins CJ. Precision of bone mechanoregulation assessment in humans using longitudinal high-resolution peripheral quantitative computed tomography in vivo. Bone 2023; 172:116780. [PMID: 37137459 DOI: 10.1016/j.bone.2023.116780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 03/31/2023] [Accepted: 04/20/2023] [Indexed: 05/05/2023]
Abstract
Local mechanical stimuli in the bone microenvironment are essential for the homeostasis and adaptation of the skeleton, with evidence suggesting that disruption of the mechanically-driven bone remodelling process may lead to bone loss. Longitudinal clinical studies have shown the combined use of high-resolution peripheral quantitative computed tomography (HR-pQCT) and micro-finite element analysis can be used to measure load-driven bone remodelling in vivo; however, quantitative markers of bone mechanoregulation and the precision of these analyses methods have not been validated in human subjects. Therefore, this study utilised participants from two cohorts. A same-day cohort (n = 33) was used to develop a filtering strategy to minimise false detections of bone remodelling sites caused by noise and motion artefacts present in HR-pQCT scans. A longitudinal cohort (n = 19) was used to develop bone imaging markers of trabecular bone mechanoregulation and characterise the precision for detecting longitudinal changes in subjects. Specifically, we described local load-driven formation and resorption sites independently using patient-specific odds ratios (OR) and 99 % confidence intervals. Conditional probability curves were computed to link the mechanical environment to the remodelling events detected on the bone surface. To quantify overall mechanoregulation, we calculated a correct classification rate measuring the fraction of remodelling events correctly identified by the mechanical signal. Precision was calculated as root-mean-squared averages of the coefficient of variation (RMS-SD) of repeated measurements using scan-rescan pairs at baseline combined with a one-year follow-up scan. We found no significant mean difference (p < 0.01) between scan-rescan conditional probabilities. RMS-SD was 10.5 % for resorption odds, 6.3 % for formation odds, and 1.3 % for correct classification rates. Bone was most likely to be formed in high-strain and resorbed in low-strain regions for all participants, indicating a consistent, regulated response to mechanical stimuli. For each percent increase in strain, the likelihood of bone resorption decreased by 2.0 ± 0.2 %, and the likelihood of bone formation increased by 1.9 ± 0.2 %, totalling 38.3 ± 1.1 % of strain-driven remodelling events across the entire trabecular compartment. This work provides novel robust bone mechanoregulation markers and their precision for designing future clinical studies.
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Affiliation(s)
- Matthias Walle
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Danielle E Whittier
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland; Department of Osteoporosis, Bern University Hospital, Bern, Switzerland
| | - Denis Schenk
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Penny R Atkins
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland; Department of Osteoporosis, Bern University Hospital, Bern, Switzerland
| | - Michael Blauth
- Department of Orthopaedics and Traumatology, Medical University Innsbruck, Innsbruck, Austria
| | - Philippe Zysset
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Kurt Lippuner
- Department of Osteoporosis, Bern University Hospital, Bern, Switzerland
| | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Caitlyn J Collins
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland; Virginia Tech, Department of Biomedical Engineering and Mechanics, Blacksburg, VA, United States.
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3
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Durongbhan P, Davey CE, Stok KS. SPHARM-PDM based image preprocessing pipeline for quantitative morphometric analysis (QMA) for in situ joint assessment in rabbit and rat models. Sci Rep 2022; 12:1113. [PMID: 35064147 PMCID: PMC8782854 DOI: 10.1038/s41598-021-04542-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 12/21/2021] [Indexed: 02/08/2023] Open
Abstract
The accessibility of quantitative measurements of joint morphometry depends on appropriate tibial alignment and volume of interest (VOI) selection of joint compartments; often a challenging and time-consuming manual task. In this work, we developed a novel automatic, efficient, and model-invariant image preprocessing pipeline that allows for highly reproducible 3D quantitative morphometric analysis (QMA) of the joint. The pipeline addresses the problem by deploying two modules: an alignment module and a subdivision module. Alignment is achieved by representing the tibia in its basic form using lower degree spherical harmonic basis functions and aligning using principal component analysis. The second module subdivides the joint into lateral and medial VOIs via a watershedding approach based on persistence homology. Multiple repeated micro-computed tomography scans of small (rat) and medium (rabbit) animal knees were processed using the pipeline to demonstrate model invariance. Existing QMA was performed to evaluate the pipeline’s ability to generate reproducible measurements. Intraclass correlation coefficient and mean-normalised root-mean-squared error of more than 0.75 and lower than 9.5%, respectively, were achieved for joint centre of mass, joint contact area under virtual loading, joint space width, and joint space volume. Processing time and technical requirements were reduced compared to manual processing in previous studies.
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Affiliation(s)
- Pholpat Durongbhan
- Department of Biomedical Engineering, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Catherine E Davey
- Department of Biomedical Engineering, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Kathryn S Stok
- Department of Biomedical Engineering, The University of Melbourne, Parkville, VIC, 3010, Australia.
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4
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Ning B, Londono I, Laporte C, Villemure I. Validation of an in vivo micro-CT-based method to quantify longitudinal bone growth of pubertal rats. Bone 2022; 154:116207. [PMID: 34547522 DOI: 10.1016/j.bone.2021.116207] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 09/13/2021] [Accepted: 09/15/2021] [Indexed: 11/02/2022]
Abstract
Bone growth is an essential part of skeletal development during childhood and puberty. Accurately characterizing longitudinal bone growth helps to better understand the determining factors of peak bone mass, which has impacts on bone quality later in life. Animal models were largely used to study longitudinal bone growth. However, the commonly used histology-based method is destructive and unable to follow up the growth curve of live animals in longitudinal experiments. In this study, we validated an in vivo micro-CT-based method against the histology-based method to quantify longitudinal bone growth rates of young rats non-destructively. CD (Sprague Dawley) IGS rats aged 35, 49 and 63 days received the same treatments: two series of repeated in vivo micro-CT scans on their proximal hind limb at a five-day interval, and two calcein injections separated by three days. The longitudinal bone growth rate was quantified by registering time-lapse micro-CT images in 3D, calculating the growth distance on registered images, and dividing the distance by the five-day gap. The growth rate was also evaluated by measuring the 2D distance between consecutive calcein fluorescent bands on microscopic images, divided by the three-day gap. The two methods were both validated independently with reproducible repeated measurements, where the micro-CT-based method showed higher precision. They were also validated against each other with low relative errors and a strong Pearson sample correlation coefficient (0.998), showing a significant (p < 0.0001) linear correlation between paired results. We conclude that the micro-CT-based method can serve as an alternative to the histology-based method for the quantification of longitudinal growth. Thanks to its non-invasive nature and true 3D capability, the micro-CT-based method helps to accommodate in vivo longitudinal animal studies with highly reproducible measurements.
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Affiliation(s)
- Bohao Ning
- Department of Mechanical Engineering, Polytechnique Montréal, P.O. Box 6079, Station Centre-Ville, Montréal, QC H3C 3A7, Canada; CHU Sainte-Justine Research Centre, 3175 Côte-Sainte-Catherine Road, Montréal, QC H3T 1C5, Canada
| | - Irène Londono
- CHU Sainte-Justine Research Centre, 3175 Côte-Sainte-Catherine Road, Montréal, QC H3T 1C5, Canada
| | - Catherine Laporte
- CHU Sainte-Justine Research Centre, 3175 Côte-Sainte-Catherine Road, Montréal, QC H3T 1C5, Canada; Department of Electrical Engineering, École de technologie supérieure, 1100 Notre-Dame Street West, Montréal, QC H3C 1K3, Canada
| | - Isabelle Villemure
- Department of Mechanical Engineering, Polytechnique Montréal, P.O. Box 6079, Station Centre-Ville, Montréal, QC H3C 3A7, Canada; CHU Sainte-Justine Research Centre, 3175 Côte-Sainte-Catherine Road, Montréal, QC H3T 1C5, Canada.
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5
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Paul GR, Wehrle E, Tourolle DC, Kuhn GA, Müller R. Real-time finite element analysis allows homogenization of tissue scale strains and reduces variance in a mouse defect healing model. Sci Rep 2021; 11:13511. [PMID: 34188165 PMCID: PMC8241979 DOI: 10.1038/s41598-021-92961-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 06/18/2021] [Indexed: 11/26/2022] Open
Abstract
Mechanical loading allows both investigation into the mechano-regulation of fracture healing as well as interventions to improve fracture-healing outcomes such as delayed healing or non-unions. However, loading is seldom individualised or even targeted to an effective mechanical stimulus level within the bone tissue. In this study, we use micro-finite element analysis to demonstrate the result of using a constant loading assumption for all mouse femurs in a given group. We then contrast this with the application of an adaptive loading approach, denoted real time Finite Element adaptation, in which micro-computed tomography images provide the basis for micro-FE based simulations and the resulting strains are manipulated and targeted to a reference distribution. Using this approach, we demonstrate that individualised femoral loading leads to a better-specified strain distribution and lower variance in tissue mechanical stimulus across all mice, both longitudinally and cross-sectionally, while making sure that no overloading is occurring leading to refracture of the femur bones.
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Affiliation(s)
- Graeme R Paul
- Institute for Biomechanics, ETH Zurich, Leopold-Ruzicka-Weg 4, 8093, Zurich, Switzerland
| | - Esther Wehrle
- Institute for Biomechanics, ETH Zurich, Leopold-Ruzicka-Weg 4, 8093, Zurich, Switzerland
| | - Duncan C Tourolle
- Institute for Biomechanics, ETH Zurich, Leopold-Ruzicka-Weg 4, 8093, Zurich, Switzerland
| | - Gisela A Kuhn
- Institute for Biomechanics, ETH Zurich, Leopold-Ruzicka-Weg 4, 8093, Zurich, Switzerland
| | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Leopold-Ruzicka-Weg 4, 8093, Zurich, Switzerland.
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6
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Walle M, Marques FC, Ohs N, Blauth M, Müller R, Collins CJ. Bone Mechanoregulation Allows Subject-Specific Load Estimation Based on Time-Lapsed Micro-CT and HR-pQCT in Vivo. Front Bioeng Biotechnol 2021; 9:677985. [PMID: 34249883 PMCID: PMC8267803 DOI: 10.3389/fbioe.2021.677985] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 05/17/2021] [Indexed: 11/20/2022] Open
Abstract
Patients at high risk of fracture due to metabolic diseases frequently undergo long-term antiresorptive therapy. However, in some patients, treatment is unsuccessful in preventing fractures or causes severe adverse health outcomes. Understanding load-driven bone remodelling, i.e., mechanoregulation, is critical to understand which patients are at risk for progressive bone degeneration and may enable better patient selection or adaptive therapeutic intervention strategies. Bone microarchitecture assessment using high-resolution peripheral quantitative computed tomography (HR-pQCT) combined with computed mechanical loads has successfully been used to investigate bone mechanoregulation at the trabecular level. To obtain the required mechanical loads that induce local variances in mechanical strain and cause bone remodelling, estimation of physiological loading is essential. Current models homogenise strain patterns throughout the bone to estimate load distribution in vivo, assuming that the bone structure is in biomechanical homoeostasis. Yet, this assumption may be flawed for investigating alterations in bone mechanoregulation. By further utilising available spatiotemporal information of time-lapsed bone imaging studies, we developed a mechanoregulation-based load estimation (MR) algorithm. MR calculates organ-scale loads by scaling and superimposing a set of predefined independent unit loads to optimise measured bone formation in high-, quiescence in medium-, and resorption in low-strain regions. We benchmarked our algorithm against a previously published load history (LH) algorithm using synthetic data, micro-CT images of murine vertebrae under defined experimental in vivo loadings, and HR-pQCT images from seven patients. Our algorithm consistently outperformed LH in all three datasets. In silico-generated time evolutions of distal radius geometries (n = 5) indicated significantly higher sensitivity, specificity, and accuracy for MR than LH (p < 0.01). This increased performance led to substantially better discrimination between physiological and extra-physiological loading in mice (n = 8). Moreover, a significantly (p < 0.01) higher association between remodelling events and computed local mechanical signals was found using MR [correct classification rate (CCR) = 0.42] than LH (CCR = 0.38) to estimate human distal radius loading. Future applications of MR may enable clinicians to link subtle changes in bone strength to changes in day-to-day loading, identifying weak spots in the bone microstructure for local intervention and personalised treatment approaches.
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Affiliation(s)
- Matthias Walle
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | | | - Nicholas Ohs
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Michael Blauth
- Department for Trauma Surgery, Innsbruck University Hospital, Innsbruck, Austria
| | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
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7
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Besler BA, Schadow JE, Durongbhan P, Steiner TH, Choo RJ, Zulliger MA, Wilke M, Atal K, Firminger C, Quintin A, Koller B, Müller R, Nesic D, Stok KS. Quantitative measures of bone shape, cartilage morphometry and joint alignment are associated with disease in an ACLT and MMx rat model of osteoarthritis. Bone 2021; 146:115903. [PMID: 33652170 DOI: 10.1016/j.bone.2021.115903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 02/11/2021] [Accepted: 02/22/2021] [Indexed: 12/16/2022]
Abstract
Multi-scale, subject-specific quantitative methods to characterize and monitor osteoarthritis in animal models and therapeutic treatments could help reveal causal relationships in disease development and distinguish treatment strategies. In this work, we demonstrate a reproducible and sensitive quantitative image analysis to characterize bone, cartilage and joint measures describing a rat model of post-traumatic osteoarthritis. Eleven 3-month-old male Wistar rats underwent medial anterior cruciate ligament (ACL) transection and medial meniscectomy on the right knee to destabilise the right tibiofemoral joint. They were sacrificed 6 weeks post-surgery and a silicon-based micro-bead contrast agent was injected in the joint space, before scanning with micro-computed tomography (microCT). Subsequently, 3D quantitative morphometric analysis (QMA), previously developed for rabbit joints, was performed. This included cartilage, subchondral cortical and epiphyseal bone measures, as well as novel tibiofemoral joint metrics. Semi-quantitative evaluation was performed on matching two-dimensional (2D) histology and microCT images. Reproducibility of the QMA was tested on eleven age-matched additional joints. The results indicate the QMA method is accurate and reproducible and that microCT-derived cartilage measurements are valid for the analysis of rat joints. The pathologic changes caused by transection of the ACL and medial meniscectomy were reflected in measurements of bone shape, cartilage morphology, and joint alignment. Furthermore, we were able to identify model-specific predictive parameters based on morphometric parameters measured with the QMA.
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Affiliation(s)
- Bryce A Besler
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland; University of Calgary, Calgary, Canada.
| | - Jemima E Schadow
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland; Department of Biomedical Engineering, The University of Melbourne, Parkville, Australia.
| | - Pholpat Durongbhan
- Department of Biomedical Engineering, The University of Melbourne, Parkville, Australia.
| | | | - Ryan J Choo
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
| | | | | | - Kailash Atal
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Colin Firminger
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
| | - Aurelie Quintin
- Department of BioMedical Research, University of Bern, Bern, Switzerland.
| | | | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
| | - Dobrila Nesic
- Department of BioMedical Research, University of Bern, Bern, Switzerland; Faculty of Medicine, University of Geneva, Geneva, Switzerland.
| | - Kathryn S Stok
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland; SCANCO Medical AG, Brüttisellen, Switzerland; Department of Biomedical Engineering, The University of Melbourne, Parkville, Australia.
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8
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Li Z, Betts D, Kuhn G, Schirmer M, Müller R, Ruffoni D. Mechanical regulation of bone formation and resorption around implants in a mouse model of osteopenic bone. J R Soc Interface 2020; 16:20180667. [PMID: 30890053 DOI: 10.1098/rsif.2018.0667] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Although mechanical stimulation is considered a promising approach to accelerate implant integration, our understanding of load-driven bone formation and resorption around implants is still limited. This lack of knowledge may delay the development of effective loading protocols to prevent implant loosening, especially in osteoporosis. In healthy bone, formation and resorption are mechanoregulated processes. In the intricate context of peri-implant bone regeneration, it is not clear whether bone (re)modelling can still be load-driven. Here, we investigated the mechanical control of peri-implant bone (re)modelling with a well-controlled mechanobiological experiment. We applied cyclic mechanical loading after implant insertion in tail vertebrae of oestrogen depleted mice and we monitored peri-implant bone response by in vivo micro-CT. Experimental data were combined with micro-finite element simulations to estimate local tissue strains in (re)modelling locations. We demonstrated that a substantial increase in bone mass around the implant could be obtained by loading the entire bone. This augmentation could be attributed to a large reduction in bone resorption rather than to an increase in bone formation. We also showed that following implantation, mechanical regulation of bone (re)modelling was transiently lost. Our findings should help to clarify the role of mechanical stimulation on the maintenance of peri-implant bone mass.
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Affiliation(s)
- Zihui Li
- 1 Institute for Biomechanics, ETH Zurich , Zurich , Switzerland
| | - Duncan Betts
- 1 Institute for Biomechanics, ETH Zurich , Zurich , Switzerland
| | - Gisela Kuhn
- 1 Institute for Biomechanics, ETH Zurich , Zurich , Switzerland
| | | | - Ralph Müller
- 1 Institute for Biomechanics, ETH Zurich , Zurich , Switzerland
| | - Davide Ruffoni
- 1 Institute for Biomechanics, ETH Zurich , Zurich , Switzerland.,3 Mechanics of Biological and Bioinspired Materials Laboratory, Department of Aerospace and Mechanical Engineering, University of Liège , Liège , Belgium
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9
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Brunet SC, Kuczynski MT, Bhatla JL, Lemay S, Pauchard Y, Salat P, Barnabe C, Manske SL. The utility of multi-stack alignment and 3D longitudinal image registration to assess bone remodeling in rheumatoid arthritis patients from second generation HR-pQCT scans. BMC Med Imaging 2020; 20:36. [PMID: 32264872 PMCID: PMC7140503 DOI: 10.1186/s12880-020-00437-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 03/27/2020] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Medical imaging plays an important role in determining the progression of joint damage in rheumatoid arthritis (RA). High resolution peripheral quantitative computed tomography (HR-pQCT) is a sensitive tool capable of evaluating bone microarchitecture and erosions, and 3D rigid image registration can be used to visualize and quantify bone remodeling over time. However, patient motion during image acquisition can cause a "stack shift" artifact resulting in loss of information and reducing the number of erosions that can be analyzed using HR-pQCT. The purpose of this study was to use image registration to improve the number of useable HR-pQCT scans and to apply image-based bone remodeling assessment to the metacarpophalangeal (MCP) joints of RA patients. METHODS Ten participants with RA completed HR-pQCT scans of the 2nd and 3rd MCP joints at enrolment to the study and at a 6-month follow-up interval. At 6-months, an additional repeat scan was acquired to evaluate reliability. HR-pQCT images were acquired in three individual 1 cm acquisitions (stacks) with a 25% overlap. We completed analysis first using standard evaluation methods, and second with multi-stack registration. We assessed whether additional erosions could be evaluated after multi-stack registration. Bone remodeling analysis was completed using registration and transformation of baseline and follow-up images. We calculated the bone formation and resorption volume fractions with 6-month follow-up, and same-day repositioning as a negative control. RESULTS 13/57 (23%) of erosions could not be analyzed from raw images due to a stack shift artifact. All erosions could be volumetrically assessed after multi-stack registration. We observed that there was a median bone formation fraction of 2.1% and resorption fraction of 3.8% in RA patients over the course of 6 months. In contrast to the same-day rescan negative control, we observed median bone formation and resorption fractions of 0%. CONCLUSIONS Multi-stack image registration is a useful tool to improve the number of useable scans when analyzing erosions using HR-pQCT. Further, image registration can be used to longitudinally assess bone remodeling. These methods could be implemented in future studies to provide important pathophysiological information on the progression of bone damage.
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Affiliation(s)
- Scott C Brunet
- Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary AB3280 Hospital Dr NW, Calgary, Alberta, T2N 4Z6, Canada.,Biomedical Engineering Graduate Program, Schulich School of Engineering, University of Calgary, Calgary, AB, Canada.,McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Michael T Kuczynski
- Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary AB3280 Hospital Dr NW, Calgary, Alberta, T2N 4Z6, Canada.,Biomedical Engineering Graduate Program, Schulich School of Engineering, University of Calgary, Calgary, AB, Canada.,McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Jennifer L Bhatla
- Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary AB3280 Hospital Dr NW, Calgary, Alberta, T2N 4Z6, Canada.,McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Sophie Lemay
- Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary AB3280 Hospital Dr NW, Calgary, Alberta, T2N 4Z6, Canada.,McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Yves Pauchard
- Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary AB3280 Hospital Dr NW, Calgary, Alberta, T2N 4Z6, Canada.,McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Peter Salat
- Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary AB3280 Hospital Dr NW, Calgary, Alberta, T2N 4Z6, Canada.,McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Cheryl Barnabe
- McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Division of Rheumatology, Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Sarah L Manske
- Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary AB3280 Hospital Dr NW, Calgary, Alberta, T2N 4Z6, Canada. .,Biomedical Engineering Graduate Program, Schulich School of Engineering, University of Calgary, Calgary, AB, Canada. .,McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
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10
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The association between mineralised tissue formation and the mechanical local in vivo environment: Time-lapsed quantification of a mouse defect healing model. Sci Rep 2020; 10:1100. [PMID: 31980656 PMCID: PMC6981157 DOI: 10.1038/s41598-020-57461-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 01/02/2020] [Indexed: 11/08/2022] Open
Abstract
An improved understanding of how local mechanical stimuli guide the fracture healing process has the potential to enhance clinical treatment of bone injury. Recent preclinical studies of bone defect in animal models have used cross-sectional data to examine this phenomenon indirectly. In this study, a direct time-lapsed imaging approach was used to investigate the local mechanical strains that precede the formation of mineralised tissue at the tissue scale. The goal was to test two hypotheses: 1) the local mechanical signal that precedes the onset of tissue mineralisation is higher in areas which mineralise, and 2) this local mechanical signal is independent of the magnitude of global mechanical loading of the tissue in the defect. Two groups of mice with femoral defects of length 0.85 mm (n = 10) and 1.45 mm (n = 9) were studied, allowing for distinct distributions of tissue scale strains in the defects. The regeneration and (re)modelling of mineralised tissue was observed weekly using in vivo micro-computed tomography (micro-CT), which served as a ground truth for resolving areas of mineralised tissue formation. The mechanical environment was determined using micro-finite element analysis (micro-FE) on baseline images. The formation of mineralised tissue showed strong association with areas of higher mechanical strain (area-under-the-curve: 0.91 ± 0.04, true positive rate: 0.85 ± 0.05) while surface based strains could correctly classify 43% of remodelling events. These findings support our hypotheses by showing a direct association between the local mechanical strains and the formation of mineralised tissue.
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11
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Zhang Y, Dall’Ara E, Viceconti M, Kadirkamanathan V. A new method to monitor bone geometry changes at different spatial scales in the longitudinal in vivo μCT studies of mice bones. PLoS One 2019; 14:e0219404. [PMID: 31329619 PMCID: PMC6645529 DOI: 10.1371/journal.pone.0219404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 06/21/2019] [Indexed: 12/17/2022] Open
Abstract
Longitudinal studies of bone adaptation in mice using in vivo micro-computed tomography (μCT) have been commonly used for pre-clinical evaluation of physical and pharmacological interventions. The main advantage of this approach is to use each mouse as its own control, reducing considerably the sample size required by statistical power analysis. To date, multi-scale estimation of bone adaptations become essential since the bone activity that takes place at different scales may be associated with different bone mechanisms. Measures of bone adaptations at different time scales have been attempted in a previous study. This paper extends quantification of bone activity at different spatial scales with a proposition of a novel framework. The method involves applying level-set method (LSM) to track the geometric changes from the longitudinal in vivo μCT scans of mice tibia. Bone low- and high-spatial frequency patterns are then estimated using multi-resolution analysis. The accuracy of the framework is quantified by applying it to two times separated scanned images with synthetically manipulated global and/or local activity. The Root Mean Square Deviation (RMSD) was approximately 1.5 voxels or 0.7 voxels for the global low-spatial frequency or local high-spatial frequency changes, respectively. The framework is further applied to the study of bone changes in longitudinal datasets of wild-type mice tibiae over time and space. The results demonstrate the ability for the spatio-temporal quantification and visualisation of bone activity at different spatial scales in longitudinal studies thus providing further insight into bone adaptation mechanisms.
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Affiliation(s)
- Yang Zhang
- Department of Automatic Control and Systems Engineering, The University of Sheffield, Sheffield, United Kingdom
- INSIGNEO Institute for in Silico Medicine, The University of Sheffield, Sheffield, United Kingdom
| | - Enrico Dall’Ara
- INSIGNEO Institute for in Silico Medicine, The University of Sheffield, Sheffield, United Kingdom
- Department of Oncology & Metabolism, The University of Sheffield, Sheffield, United Kingdom
| | - Marco Viceconti
- Department of Industrial Engineering, Alma Mater Studiorum, University of Bologna, Bologna Area, Italy
- Medical Technology Lab, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Visakan Kadirkamanathan
- Department of Automatic Control and Systems Engineering, The University of Sheffield, Sheffield, United Kingdom
- INSIGNEO Institute for in Silico Medicine, The University of Sheffield, Sheffield, United Kingdom
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Christen P, Boutroy S, Ellouz R, Chapurlat R, van Rietbergen B. Least-detectable and age-related local in vivo bone remodelling assessed by time-lapse HR-pQCT. PLoS One 2018; 13:e0191369. [PMID: 29364934 PMCID: PMC5783377 DOI: 10.1371/journal.pone.0191369] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 01/03/2018] [Indexed: 01/05/2023] Open
Abstract
We previously developed an image analysis approach for the determination of local sites of bone remodelling using time-lapse in vivo HR-pQCT. The involved image filtering for removing noise was chosen rather aggressively, and also removed some effects of the bone remodelling. In this paper, we quantify these filtering settings using ex vivo reproducibility HR-pQCT images, and determine the least-detectable bone remodelling using in vivo reproducibility HR-pQCT images, as well as testing whether the approach is capable of capturing age-related bone remodelling by use of in vivo long-term HR-pQCT images. We found that a threshold value of 225 mg HA/cm3 for the filtering led to acceptable results with falsely determined bone remodelling of less than 0.5%, and that the least-detectable bone formation and bone resorption are 2.0 ± 1.0% and 2.2 ± 0.7% respectively. We also found that age-related local bone remodelling can be captured satisfactorily in postmenopausal women. The latter revealed new insights into the effect of ageing on bone remodelling, and showed that bone remodelling seems to take place through a few small formation packets and many large resorption volumes leading to a net bone loss. We conclude that local in vivo bone remodelling can be successfully assessed with time-lapse in vivo HR-pQCT capable of assessing age-related changes in bone remodelling.
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Affiliation(s)
- Patrik Christen
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
- * E-mail:
| | | | - Rafaa Ellouz
- INSERM UMR 1033, Université de Lyon, Lyon, France
| | | | - Bert van Rietbergen
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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Li Z, Kuhn G, Schirmer M, Müller R, Ruffoni D. Impaired bone formation in ovariectomized mice reduces implant integration as indicated by longitudinal in vivo micro-computed tomography. PLoS One 2017; 12:e0184835. [PMID: 28910363 PMCID: PMC5599039 DOI: 10.1371/journal.pone.0184835] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 08/31/2017] [Indexed: 12/29/2022] Open
Abstract
Although osteoporotic bone, with low bone mass and deteriorated bone architecture, provides a less favorable mechanical environment than healthy bone for implant fixation, there is no general agreement on the impact of osteoporosis on peri-implant bone (re)modeling, which is ultimately responsible for the long term stability of the bone-implant system. Here, we inserted an implant in a mouse model mimicking estrogen deficiency-induced bone loss and we monitored with longitudinal in vivo micro-computed tomography the spatio-temporal changes in bone (re)modeling and architecture, considering the separate contributions of trabecular, endocortical and periosteal surfaces. Specifically, 12 week-old C57BL/6J mice underwent OVX/SHM surgery; 9 weeks after we inserted special metal-ceramics implants into the 6th caudal vertebra and we measured bone response with in vivo micro-CT weekly for the following 6 weeks. Our results indicated that ovariectomized mice showed a reduced ability to increase the thickness of the cortical shell close to the implant because of impaired peri-implant bone formation, especially at the periosteal surface. Moreover, we observed that healthy mice had a significantly higher loss of trabecular bone far from the implant than estrogen depleted animals. Such behavior suggests that, in healthy mice, the substantial increase in peri-implant bone formation which rapidly thickened the cortex to secure the implant may raise bone resorption elsewhere and, specifically, in the trabecular network of the same bone but far from the implant. Considering the already deteriorated bone structure of estrogen depleted mice, further bone loss seemed to be hindered. The obtained knowledge on the dynamic response of diseased bone following implant insertion should provide useful guidelines to develop advanced treatments for osteoporotic fracture fixation based on local and selective manipulation of bone turnover in the peri-implant region.
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Affiliation(s)
- Zihui Li
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Gisela Kuhn
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | | | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Davide Ruffoni
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
- Mechanics of Biological and Bioinspired Materials Research Unit, Department of Aerospace and Mechanical Engineering, University of Liège, Liège, Belgium
- * E-mail:
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14
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Christen P, Schulte FA, Zwahlen A, van Rietbergen B, Boutroy S, Melton LJ, Amin S, Khosla S, Goldhahn J, Müller R. Voxel size dependency, reproducibility and sensitivity of an in vivo bone loading estimation algorithm. J R Soc Interface 2016; 13:20150991. [PMID: 26790999 DOI: 10.1098/rsif.2015.0991] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A bone loading estimation algorithm was previously developed that provides in vivo loading conditions required for in vivo bone remodelling simulations. The algorithm derives a bone's loading history from its microstructure as assessed by high-resolution (HR) computed tomography (CT). This reverse engineering approach showed accurate and realistic results based on micro-CT and HR-peripheral quantitative CT images. However, its voxel size dependency, reproducibility and sensitivity still need to be investigated, which is the purpose of this study. Voxel size dependency was tested on cadaveric distal radii with micro-CT images scanned at 25 µm and downscaled to 50, 61, 75, 82, 100, 125 and 150 µm. Reproducibility was calculated with repeated in vitro as well as in vivo HR-pQCT measurements at 82 µm. Sensitivity was defined using HR-pQCT images from women with fracture versus non-fracture, and low versus high bone volume fraction, expecting similar and different loading histories, respectively. Our results indicate that the algorithm is voxel size independent within an average (maximum) error of 8.2% (32.9%) at 61 µm, but that the dependency increases considerably at voxel sizes bigger than 82 µm. In vitro and in vivo reproducibility are up to 4.5% and 10.2%, respectively, which is comparable to other in vitro studies and slightly higher than in other in vivo studies. Subjects with different bone volume fraction were clearly distinguished but not subjects with and without fracture. This is in agreement with bone adapting to customary loading but not to fall loads. We conclude that the in vivo bone loading estimation algorithm provides reproducible, sensitive and fairly voxel size independent results at up to 82 µm, but that smaller voxel sizes would be advantageous.
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Affiliation(s)
| | | | | | - Bert van Rietbergen
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Stephanie Boutroy
- INSERM UMR 1033, Hôpital Edouard Herriot, Université de Lyon, Lyon, France
| | - L Joseph Melton
- Division of Epidemiology, Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA
| | - Shreyasee Amin
- Division of Epidemiology, Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA Division of Rheumatology, Department of Internal Medicine, Mayo Clinic, Rochester, MN, USA
| | - Sundeep Khosla
- Division of Endocrinology, Diabetes, Metabolism and Nutrition, Department of Internal Medicine, Mayo Clinic, Rochester, MN, USA
| | - Jörg Goldhahn
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland Novartis, Institutes for BioMedical Research (NIBR), Basel, Switzerland
| | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
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15
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Stok KS, Besler BA, Steiner TH, Villarreal Escudero AV, Zulliger MA, Wilke M, Atal K, Quintin A, Koller B, Müller R, Nesic D. Three-Dimensional Quantitative Morphometric Analysis (QMA) for In Situ Joint and Tissue Assessment of Osteoarthritis in a Preclinical Rabbit Disease Model. PLoS One 2016; 11:e0147564. [PMID: 26808542 PMCID: PMC4726512 DOI: 10.1371/journal.pone.0147564] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 01/05/2016] [Indexed: 11/23/2022] Open
Abstract
This work utilises advances in multi-tissue imaging, and incorporates new metrics which define in situ joint changes and individual tissue changes in osteoarthritis (OA). The aims are to (1) demonstrate a protocol for processing intact animal joints for microCT to visualise relevant joint, bone and cartilage structures for understanding OA in a preclinical rabbit model, and (2) introduce a comprehensive three-dimensional (3D) quantitative morphometric analysis (QMA), including an assessment of reproducibility. Sixteen rabbit joints with and without transection of the anterior cruciate ligament were scanned with microCT and contrast agents, and processed for histology. Semi-quantitative evaluation was performed on matching two-dimensional (2D) histology and microCT images. Subsequently, 3D QMA was performed; including measures of cartilage, subchondral cortical and epiphyseal bone, and novel tibio-femoral joint metrics. Reproducibility of the QMA was tested on seven additional joints. A significant correlation was observed in cartilage thickness from matching histology-microCT pairs. The lateral compartment of operated joints had larger joint space width, thicker femoral cartilage and reduced bone volume, while osteophytes could be detected quantitatively. Measures between the in situ tibia and femur indicated an altered loading scenario. High measurement reproducibility was observed for all new parameters; with ICC ranging from 0.754 to 0.998. In conclusion, this study provides a novel 3D QMA to quantify macro and micro tissue measures in the joint of a rabbit OA model. New metrics were established consisting of: an angle to quantitatively measure osteophytes (σ), an angle to indicate erosion between the lateral and medial femoral condyles (ρ), a vector defining altered angulation (λ, α, β, γ) and a twist angle (τ) measuring instability and tissue degeneration between the femur and tibia, a length measure of joint space width (JSW), and a slope and intercept (m, Χ) of joint contact to demonstrate altered loading with disease progression, as well as traditional bone and cartilage and histo-morphometry measures. We demonstrate correlation of microCT and histology, sensitive discrimination of OA change and robust reproducibility.
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Affiliation(s)
- Kathryn S. Stok
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
- SCANCO Medical AG, Bruttisellen, Switzerland
- * E-mail:
| | | | | | | | | | - Markus Wilke
- Department of Clinical Research, University of Bern, Bern, Switzerland
| | - Kailash Atal
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Aurelie Quintin
- Department of Clinical Research, University of Bern, Bern, Switzerland
| | | | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Dobrila Nesic
- Department of Clinical Research, University of Bern, Bern, Switzerland
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Minimizing Interpolation Bias and Precision Error in In Vivo µCT-Based Measurements of Bone Structure and Dynamics. Ann Biomed Eng 2016; 44:2518-2528. [PMID: 26786342 DOI: 10.1007/s10439-015-1527-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 12/08/2015] [Indexed: 01/28/2023]
Abstract
In vivo µCT imaging allows for high-resolution, longitudinal evaluation of bone properties. Based on this technology, several recent studies have developed in vivo dynamic bone histomorphometry techniques that utilize registered µCT images to identify regions of bone formation and resorption, allowing for longitudinal assessment of bone remodeling. However, this analysis requires a direct voxel-by-voxel subtraction between image pairs, necessitating rotation of the images into the same coordinate system, which introduces interpolation errors. We developed a novel image transformation scheme, matched-angle transformation (MAT), whereby the interpolation errors are minimized by equally rotating both the follow-up and baseline images instead of the standard of rotating one image while the other remains fixed. This new method greatly reduced interpolation biases caused by the standard transformation. Additionally, our study evaluated the reproducibility and precision of bone remodeling measurements made via in vivo dynamic bone histomorphometry. Although bone remodeling measurements showed moderate baseline noise, precision was adequate to measure physiologically relevant changes in bone remodeling, and measurements had relatively good reproducibility, with intra-class correlation coefficients of 0.75-0.95. This indicates that, when used in conjunction with MAT, in vivo dynamic histomorphometry provides a reliable assessment of bone remodeling.
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17
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Spatial relationships between bone formation and mechanical stress within cancellous bone. J Biomech 2016; 49:222-8. [DOI: 10.1016/j.jbiomech.2015.12.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 11/02/2015] [Accepted: 12/03/2015] [Indexed: 12/15/2022]
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18
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Evaluation of in-vivo measurement errors associated with micro-computed tomography scans by means of the bone surface distance approach. Med Eng Phys 2015; 37:1091-7. [DOI: 10.1016/j.medengphy.2015.08.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Revised: 03/31/2015] [Accepted: 08/07/2015] [Indexed: 01/01/2023]
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19
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The influence of age on adaptive bone formation and bone resorption. Biomaterials 2014; 35:9290-301. [PMID: 25128376 DOI: 10.1016/j.biomaterials.2014.07.051] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 07/23/2014] [Indexed: 12/11/2022]
Abstract
Bone is a tissue with enormous adaptive capacity, balancing resorption and formation processes. It is known that mechanical loading shifts this balance towards an increased formation, leading to enhanced bone mass and mechanical performance. What is not known is how this adaptive response to mechanical loading changes with age. Using dynamic micro-tomography, we show that structural adaptive changes of trabecular bone within the tibia of living mice subjected to two weeks of in vivo cyclic loading are altered by aging. Comparisons of 10, 26 and 78 weeks old animals reveal that the adaptive capacity diminishes. Strikingly, adaptation was asymmetric in that loading increases formation more than it reduces resorption. This asymmetry further shifts the (re)modeling balance towards a net bone loss with age. Loading results in a major increase in the surface area of mineralizing bone. Interestingly, the resorption thickness is independent of loading in trabecular bone in all age groups. This data suggests that during youth, mechanical stimulation induces the recruitment of bone modeling cells whereas in old age, only bone forming cells are affected. These findings provide mechanistic insights into the processes that guide skeletal aging in mice as well as in other mammals.
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Schulte FA, Ruffoni D, Lambers FM, Christen D, Webster DJ, Kuhn G, Müller R. Local mechanical stimuli regulate bone formation and resorption in mice at the tissue level. PLoS One 2013; 8:e62172. [PMID: 23637993 PMCID: PMC3634859 DOI: 10.1371/journal.pone.0062172] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 03/18/2013] [Indexed: 11/24/2022] Open
Abstract
Bone is able to react to changing mechanical demands by adapting its internal microstructure through bone forming and resorbing cells. This process is called bone modeling and remodeling. It is evident that changes in mechanical demands at the organ level must be interpreted at the tissue level where bone (re)modeling takes place. Although assumed for a long time, the relationship between the locations of bone formation and resorption and the local mechanical environment is still under debate. The lack of suitable imaging modalities for measuring bone formation and resorption in vivo has made it difficult to assess the mechanoregulation of bone three-dimensionally by experiment. Using in vivo micro-computed tomography and high resolution finite element analysis in living mice, we show that bone formation most likely occurs at sites of high local mechanical strain (p<0.0001) and resorption at sites of low local mechanical strain (p<0.0001). Furthermore, the probability of bone resorption decreases exponentially with increasing mechanical stimulus (R2 = 0.99) whereas the probability of bone formation follows an exponential growth function to a maximum value (R2 = 0.99). Moreover, resorption is more strictly controlled than formation in loaded animals, and ovariectomy increases the amount of non-targeted resorption. Our experimental assessment of mechanoregulation at the tissue level does not show any evidence of a lazy zone and suggests that around 80% of all (re)modeling can be linked to the mechanical micro-environment. These findings disclose how mechanical stimuli at the tissue level contribute to the regulation of bone adaptation at the organ level.
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Affiliation(s)
| | - Davide Ruffoni
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | | | - David Christen
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | | | - Gisela Kuhn
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
- * E-mail:
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21
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Lambers FM, Stuker F, Weigt C, Kuhn G, Koch K, Schulte FA, Ripoll J, Rudin M, Müller R. Longitudinal in vivo imaging of bone formation and resorption using fluorescence molecular tomography. Bone 2013; 52:587-95. [PMID: 23142804 DOI: 10.1016/j.bone.2012.11.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 10/24/2012] [Accepted: 11/01/2012] [Indexed: 11/23/2022]
Abstract
Bone research often focuses on anatomical imaging of the bone microstructure, but in order to gain better understanding in how bone remodeling is modulated through interventions also bone formation and resorption processes should be investigated. With this in mind, the purpose of this study was to establish a longitudinal in vivo imaging approach of bone formation and resorption using fluorescence molecular tomography (FMT). In this study the reproducibility, accuracy and sensitivity of FMT for bone imaging were assessed by performing longitudinal measurements with FMT and comparing it to in vivo micro-computed tomography on a set of control mice, and mice in which load-adaptation was induced in the sixth caudal vertebra. The precision error for FMT measurements, expressed as coefficient of variation, was smaller than 16%, indicating acceptable reproducibility. A correlation was found between bone resorption measured with FMT and bone resorption rate measured with in vivo micro-computed tomography only over the first 14days (R=0.81, p<0.01), but not between bone formation measured with FMT and bone formation rate measured with in vivo micro-CT. Bone formation measured by FMT was 89-109% greater (p<0.05) for mice subjected to mechanical loading than control mice. Bone resorption was 5-8% lower, but did not reach a significant difference between groups, indicating moderate sensitivity for FMT. In conclusion, in vivo FMT in mouse tail bones is feasible but needs to be optimized for monitoring load adaptation in living mice.
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Affiliation(s)
- F M Lambers
- Institute for Biomechanics, ETH Zürich, Zürich, Switzerland
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