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Warnung L, Sattler S, Haiden E, Schober S, Pahr D, Reisinger A. A mechanically validated open-source silicone model for the training of gastric perforation sewing. BMC Med Educ 2023; 23:261. [PMID: 37076839 PMCID: PMC10116820 DOI: 10.1186/s12909-023-04174-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 03/17/2023] [Indexed: 05/03/2023]
Abstract
BACKGROUND Gastrointestinal perforation is commonly seen in emergency departments. The perforation of the stomach is an emergency situation that requires immediate surgical treatment. The necessary surgical skills require regular practical training. Owing to patient`s safety, in vivo training opportunities in medicine are restricted. Animal tissue especially porcine tissue, is commonly used for surgical training. Due to its limiting factors, artificial training models are often to be preferred. Many artificial models are on the market but to our knowledge, none that mimic the haptic- and sewing properties of a stomach wall at the same time. In this study, an open source silicone model of a gastric perforation for training of gastric sewing was developed that attempts to provide realistic haptic- and sewing behaviour. METHODS To simulate the layered structure of the human stomach, different silicone materials were used to produce three different model layups. The production process was kept as simple as possible to make it easily reproducible. A needle penetration setup as well as a systematic haptic evaluation were developed to compare these silicone models to a real porcine stomach in order to identify the most realistic model. RESULTS A silicone model consisting of three layers was identified as being the most promising and was tested by clinical surgeons. CONCLUSIONS The presented model simulates the sewing characteristics of a human stomach wall, is easily reproducible at low-costs and can be used for practicing gastric suturing techniques. TRIAL REGISTRATIONS Not applicable.
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Affiliation(s)
- Lukas Warnung
- Department of Anatomy and Biomechanics, Division Biomechanics, Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, Krems, 3500, Austria.
- Division of Radiotherapy-Radiation Oncology, University Hospital Krems, Mitterweg 10, Krems, 3500, Austria.
| | - Stefan Sattler
- Department of Surgery, University Hospital Tulln, Alter Ziegelweg 10, Tulln, 3430, Austria
- Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, Krems, 3500, Austria
| | - Elmar Haiden
- Department of Surgery, University Hospital Tulln, Alter Ziegelweg 10, Tulln, 3430, Austria
- Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, Krems, 3500, Austria
| | - Sophie Schober
- Medical Science and Human Medicine study programme, Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, Krems, 3500, Austria
| | - Dieter Pahr
- Department of Anatomy and Biomechanics, Division Biomechanics, Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, Krems, 3500, Austria
- Institute for Lightweight Design and Structural Biomechanics, University of Technology Vienna, Getreidemarkt 9, Wien, 1060, Austria
| | - Andreas Reisinger
- Department of Anatomy and Biomechanics, Division Biomechanics, Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, Krems, 3500, Austria
- Institute for Lightweight Design and Structural Biomechanics, University of Technology Vienna, Getreidemarkt 9, Wien, 1060, Austria
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Amini M, Reisinger A, Synek A, Hirtler L, Pahr D. The predictive ability of a QCT-FE model of the proximal femoral stiffness under multiple load cases is strongly influenced by experimental uncertainties. J Mech Behav Biomed Mater 2023; 139:105664. [PMID: 36657193 DOI: 10.1016/j.jmbbm.2023.105664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/03/2023] [Accepted: 01/05/2023] [Indexed: 01/11/2023]
Abstract
Despite significant improvements in terms of the predictive ability of Quantitative Computed Tomography based Finite Element (QCT-FE) models in estimating femoral strength (fracture load and stiffness), no substantial clinical adoption of this method has taken place to date. Narrowing the wide variability of FE results by standardizing the methodology and validation protocols, as well as reducing the uncertainties in the FEA process have been proposed as routes towards improved reliability. The aim of this study was to: First, validate a QCT-FE model of proximal femoral stiffness in multiple stance load cases, and second, using a parametric approach, determine the influence of select experimental and modeling parameters on the predictive ability of our model. Ten fresh frozen human femoral samples were tested in neutral stance, 15° adducted and 15° abducted load cases. Voxel-based linear-elastic QCT-FE models of the samples were generated to predict the models' stiffness values in all load cases. The base FE models were validated against the experimental results using linear regression. Thirty six deviated models were created using the minimum and maximum values of experiment-based "plausible range" for 18 parameters in 4 categories of embedding, loading, material, and segmentation. The predictive ability of the models were compared in terms of the coefficient of determination (R2) of the linear regression between the measured and predicted stiffness values in all load cases. Our model was capable of capturing 90% of the variation in the experimental stiffness of the samples in neutral stance position (R2 = 0.9, concordance correlation coefficient (CCC) = 0.93, percent root mean squared error (RMSE%) = 8.4%, slope and intercept not significantly different from unity and zero, respectively). Embedding and loading categories strongly affected the predictive ability of the models with an average percent difference in R2 of 4.36% ± 2.77 and 2.96% ± 1.69 for the stance-neutral load case, respectively. The performance of the models were significantly different in adducted and abducted load cases with their R2 dropping to 71% and 70%, respectively. Similarly, off-axes load cases were affected by the parameters differently compared to the neutral load case, with the loading parameter category imposing more than 10% difference on their R2, larger than all other categories. We also showed that automatically selecting the best performing plausible value for each parameter and each sample would result in a perfectly linear correlation (R2> 0.99) between the "tuned" model's predicted stiffness and experimental results. Based on our results, high sensitivity of the model performance to experimental parameters requires extra diligence in modeling the embedding geometry and the loading angles since these sources of uncertainty could dwarf the effects of material modeling and image processing parameters. The results of this study could help in improving the robustness of the QCT-FE models of proximal femur by limiting the uncertainties in the experimental and modeling steps.
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Affiliation(s)
- Morteza Amini
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria.
| | - Andreas Reisinger
- Division Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, 3500 Krems an der Donau, Austria.
| | - Alexander Synek
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria.
| | - Lena Hirtler
- Center for Anatomy and Cell Biology, Medical University of Vienna, Währinger Straße 13, 1090, Vienna, Austria.
| | - Dieter Pahr
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria; Division Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, 3500 Krems an der Donau, Austria.
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Nägl K, Reisinger A, Pahr DH. The biomechanical behavior of 3D printed human femoral bones based on generic and patient-specific geometries. 3D Print Med 2022; 8:35. [DOI: 10.1186/s41205-022-00162-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 10/18/2022] [Indexed: 11/25/2022] Open
Abstract
Abstract
Background
Bone is a highly complex composite material which makes it hard to find appropriate artificial surrogates for patient-specific biomechanical testing. Despite various options of commercially available bones with generic geometries, these are either biomechanically not very realistic or rather expensive.
Methods
In this work, additive manufacturing was used for the fabrication of artificial femoral bones. These were based on CT images of four different commercially available femoral bone surrogates and three human bones with varying bone density. The models were 3D printed using a low-budget fused deposition modeling (FDM) 3D printer and PLA filament. The infill density was mechanically calibrated and varying cortical thickness was used. Compression tests of proximal femora simulating stance were performed and the biomechanical behavior concerning ultimate force, spring stiffness, and fracture pattern were evaluated as well as compared to the results of commercial and cadaveric bones.
Results
Regarding the ultimate forces and spring stiffness, the 3D printed analogs showed mechanical behavior closer to their real counterparts than the commercially available polyurethan-based surrogates. Furthermore, the increase in ultimate force with increasing bone density observed in human femoral bones could be reproduced well. Also, the fracture patterns observed match well with fracture patterns observed in human hip injuries.
Conclusion
Consequently, the methods presented here show to be a promising alternative for artificial generic surrogates concerning femoral strength testing. The manufacturing is straightforward, cheap, and patient-specific geometries are possible.
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Streicher J, Reisinger A, Warnung L, Pahr D. 3D‐Printing Offers Dry Replication and New Insight into Unique Museum Specimens. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r2197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Johannes Streicher
- Anatomy and BiomechanicsKarl Landsteiner University of Health SciencesKrems
| | - Andreas Reisinger
- Anatomy and BiomechanicsKarl Landsteiner University of Health SciencesKrems
| | - Lukas Warnung
- Anatomy and BiomechanicsKarl Landsteiner University of Health SciencesKrems
| | - Dieter Pahr
- Anatomy and BiomechanicsKarl Landsteiner University of Health SciencesKrems
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Zupancic Cepic L, Frank M, Reisinger A, Pahr D, Zechner W, Schedle A. Biomechanical finite element analysis of short-implant-supported, 3-unit, fixed CAD/CAM prostheses in the posterior mandible. Int J Implant Dent 2022; 8:8. [PMID: 35147791 PMCID: PMC8837704 DOI: 10.1186/s40729-022-00404-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 01/17/2022] [Indexed: 11/21/2022] Open
Abstract
Objective To assess the biomechanical effects of different prosthetic/implant configurations and load directions on 3-unit fixed prostheses supported by short dental implants in the posterior mandible using validated 3-D finite element (FE) models.
Methods Models represented an atrophic mandible, missing the 2nd premolar, 1st and 2nd molars, and rehabilitated with either two short implants (implant length-IL = 8 mm and 4 mm) supporting a 3-unit dental bridge or three short implants (IL = 8 mm, 6 mm and 4 mm) supporting zirconia prosthesis in splinted or single crowns design. Load simulations were performed in ABAQUS (Dassault Systèmes, France) under axial and oblique (30°) force of 100 N to assess the global stiffness and forces within the implant prosthesis. Local stresses within implant/prosthesis system and strain energy density (SED) within surrounding bone were determined and compared between configurations. Results The global stiffness was around 1.5 times higher in splinted configurations vs. single crowns, whereby off-axis loading lead to a decrease of 39%. Splinted prostheses exhibited a better stress distribution than single crowns. Local stresses were larger and distributed over a larger area under oblique loads compared to axial load direction. The forces on each implant in the 2-implant-splinted configurations increased by 25% compared to splinted crowns on 3 implants. Loading of un-splinted configurations resulted in increased local SED magnitude. Conclusion Splinting of adjacent short implants in posterior mandible by the prosthetic restoration has a profound effect on the magnitude and distribution of the local stress peaks in peri-implant regions. Replacing each missing tooth with an implant is recommended, whenever bone supply and costs permit.
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Affiliation(s)
- Lana Zupancic Cepic
- Department of Prosthodontics, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria
| | - Martin Frank
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
| | - Andreas Reisinger
- Division Biomechanics, Department of Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - Dieter Pahr
- Division Biomechanics, Department of Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - Werner Zechner
- Department of Oral Surgery, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria
| | - Andreas Schedle
- Competence Centre Dental Materials, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria.
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Amini M, Reisinger A, Hirtler L, Pahr D. Which experimental procedures influence the apparent proximal femoral stiffness? A parametric study. BMC Musculoskelet Disord 2021; 22:815. [PMID: 34556078 PMCID: PMC8461859 DOI: 10.1186/s12891-021-04656-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 08/26/2021] [Indexed: 11/10/2022] Open
Abstract
Background Experimental validation is the gold standard for the development of FE predictive models of bone. Employing multiple loading directions could improve this process. To capture the correct directional response of a sample, the effect of all influential parameters should be systematically considered. This study aims to determine the impact of common experimental parameters on the proximal femur’s apparent stiffness. Methods To that end, a parametric approach was taken to study the effects of: repetition, pre-loading, re-adjustment, re-fixation, storage, and μCT scanning as random sources of uncertainties, and loading direction as the controlled source of variation in both stand and side-fall configurations. Ten fresh-frozen proximal femoral specimens were prepared and tested with a novel setup in three consecutive sets of experiments. The neutral state and 15-degree abduction and adduction angles in both stance and fall configurations were tested for all samples and parameters. The apparent stiffness of the samples was measured using load-displacement data from the testing machine and validated against marker displacement data tracked by DIC cameras. Results Among the sources of uncertainties, only the storage cycle affected the proximal femoral apparent stiffness significantly. The random effects of setup manipulation and intermittent μCT scanning were negligible. The 15∘ deviation in loading direction had a significant effect comparable in size to that of switching the loading configuration from neutral stance to neutral side-fall. Conclusion According to these results, comparisons between the stiffness of the samples under various loading scenarios can be made if there are no storage intervals between the different load cases on the same samples. These outcomes could be used as guidance in defining a highly repeatable and multi-directional experimental validation study protocol.
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Affiliation(s)
- Morteza Amini
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Getreidemarkt 9, Vienna, 1060, Austria.,Division Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, Krems an der Donau, 3500, Austria
| | - Andreas Reisinger
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Getreidemarkt 9, Vienna, 1060, Austria.,Division Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, Krems an der Donau, 3500, Austria
| | - Lena Hirtler
- Center for Anatomy and Cell Biology, Medical University of Vienna, Währinger Straße 13, Vienna, 1090, Austria
| | - Dieter Pahr
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Getreidemarkt 9, Vienna, 1060, Austria. .,Division Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, Krems an der Donau, 3500, Austria.
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Estermann SJ, Pahr DH, Reisinger A. Hyperelastic and viscoelastic characterization of hepatic tissue under uniaxial tension in time and frequency domain. J Mech Behav Biomed Mater 2020; 112:104038. [PMID: 32889334 DOI: 10.1016/j.jmbbm.2020.104038] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/03/2020] [Accepted: 08/10/2020] [Indexed: 01/28/2023]
Abstract
In order to create accurate anatomical models for medical training and research, mechanical properties of biological tissues need to be studied. However, non-linear and viscoelastic behaviour of most soft biological tissues complicates the evaluation of their mechanical properties. In the current study, a method for measuring hyperelasticity and viscoelasticity of bovine and porcine hepatic parenchyma in tension is presented. First, non-linear stress-stretch curves resulting from ramp loading and unloading, were interpreted based on a hyperelastic framework, using a Veronda-Westmann strain energy function. Strain-specific elastic moduli, such as initial stiffness EI, were thereupon defined in certain parts of the stress-stretch curves. Furthermore, dissipated and stored energy density were calculated. Next, the viscoelastic nature of liver tissue was examined with two different methods: stress relaxation and dynamic cyclic testing. Both tests yielded dissipated and stored energy density, as well as loss tangent (tanδ), storage modulus (E'), and loss modulus (E''). In tension, stress relaxation was experimentally more convenient than dynamic cyclic testing. Thus we considered whether relaxation could be used for approximating the results of the cyclic tests. Regarding the resulting elastic moduli, initial stiffness was similar for porcine and bovine liver (EI∼30kPa), while porcine liver was stiffer for higher strains. Comparing stress relaxation with dynamic cyclic testing, tanδ of porcine and bovine liver was the same for both methods (tanδ=0.05-0.25 at 1 Hz). Storage and loss moduli matched well for bovine, but not as well for porcine tissue. In conclusion, the utilized Veronda-Westmann model was appropriate for representing the hyperelasticity of liver tissue seen in ramp tests. Concerning viscoelasticity, both chosen testing methods - stress relaxation and dynamic cyclic testing - yielded comparable results for E', E'', and tanδ, as long as elasticity non-linearities were heeded. The here presented method provides novel insight into the tensile viscoelastic properties of hepatic tissue, and provides guidelines for convenient evaluation of soft tissue mechanical properties.
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Affiliation(s)
- Sarah-Jane Estermann
- Department Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, 3500 Krems an der Donau, Austria; Austrian Center for Medical Innovation and Technology, Viktor Kaplan-Straße 2/1, 2700 Wiener Neustadt, Austria; Institute for Lightweight Design and Structural Biomechanics, TU-Wien, Getreidemarkt 9, 1060 Wien, Austria
| | - Dieter H Pahr
- Department Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, 3500 Krems an der Donau, Austria; Institute for Lightweight Design and Structural Biomechanics, TU-Wien, Getreidemarkt 9, 1060 Wien, Austria
| | - Andreas Reisinger
- Department Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, 3500 Krems an der Donau, Austria.
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Iori G, Schneider J, Reisinger A, Heyer F, Peralta L, Wyers C, Glüer CC, van den Bergh JP, Pahr D, Raum K. Cortical thinning and accumulation of large cortical pores in the tibia reflect local structural deterioration of the femoral neck. Bone 2020; 137:115446. [PMID: 32450342 DOI: 10.1016/j.bone.2020.115446] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 05/03/2020] [Accepted: 05/19/2020] [Indexed: 01/09/2023]
Abstract
INTRODUCTION Cortical bone thinning and a rarefaction of the trabecular architecture represent possible causes of increased femoral neck (FN) fracture risk. Due to X-ray exposure limits, the bone microstructure is rarely measurable in the FN of subjects but can be assessed at the tibia. Here, we studied whether changes of the tibial cortical microstructure, which were previously reported to be associated with femur strength, are also associated with structural deteriorations of the femoral neck. METHODS The cortical and trabecular architectures in the FN of 19 humans were analyzed ex vivo on 3D microcomputed tomography images with 30.3 μm voxel size. Cortical thickness (Ct.Thtibia), porosity (Ct.Potibia) and pore size distribution in the tibiae of the same subjects were measured using scanning acoustic microscopy (12 μm pixel size). Femur strength during sideways falls was simulated with homogenized voxel finite element models. RESULTS Femur strength was associated with the total (vBMDtot; R2 = 0.23, p < 0.01) and trabecular (vBMDtrab; R2 = 0.26, p < 0.01) volumetric bone mineral density (vBMD), with the cortical thickness (Ct.ThFN; R2 = 0.29, p < 0.001) and with the trabecular bone volume fraction (Tb.BV/TVFN; R2 = 0.34, p < 0.001), separation (Tb.SpFN; R2 = 0.25, p < 0.01) and number (Tb.NFN; R2 = 0.32, p < 0.001) of the femoral neck. Moreover, smaller Ct.Thtibia was associated with smaller Ct.ThFN (R2 = 0.31, p < 0.05), lower Tb.BV/TVFN (R2 = 0.29, p < 0.05), higher Tb.SpFN (R2 = 0.33, p < 0.05) and lower Tb.NFN (R2 = 0.42, p < 0.01). A higher prevalence of pores with diameter > 100 μm in tibial cortical bone (relCt.Po100μm-tibia) indicated higher Tb.SpFN (R2 = 0.36, p < 0.01) and lower Tb.NFN (R2 = 0.45, p < 0.01). CONCLUSION Bone resorption and structural decline of the femoral neck may be identified in vivo by measuring cortical bone thickness and large pores in the tibia.
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Affiliation(s)
- Gianluca Iori
- Berlin-Brandenburg Center for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Johannes Schneider
- Berlin-Brandenburg Center for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Andreas Reisinger
- Division Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - Frans Heyer
- Department of Internal Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands; Department of Internal Medicine, VieCuri Medical Center, Venlo, the Netherlands
| | - Laura Peralta
- Laboratoire d'Imagerie Biomédicale, Sorbonne Universités, INSERM UMR S 1146, CNRS UMR 7371, Paris, France; Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, London, UK
| | - Caroline Wyers
- Department of Internal Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands; Department of Internal Medicine, VieCuri Medical Center, Venlo, the Netherlands
| | - Claus C Glüer
- Sektion Biomedizinische Bildgebung, Klinik für Radiologie und Neuroradiologie, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - J P van den Bergh
- Department of Internal Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands; Department of Internal Medicine, VieCuri Medical Center, Venlo, the Netherlands
| | - Dieter Pahr
- Division Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria; Institute for Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
| | - Kay Raum
- Berlin-Brandenburg Center for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
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Iori G, Peralta L, Reisinger A, Heyer F, Wyers C, van den Bergh J, Pahr D, Raum K. Femur strength predictions by nonlinear homogenized voxel finite element models reflect the microarchitecture of the femoral neck. Med Eng Phys 2020; 79:60-66. [PMID: 32291201 DOI: 10.1016/j.medengphy.2020.03.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 03/10/2020] [Accepted: 03/17/2020] [Indexed: 12/16/2022]
Abstract
In the human femoral neck, the contribution of the cortical and trabecular architecture to mechanical strength is known to depend on the load direction. In this work, we investigate if QCT-derived homogenized voxel finite element (hvFE) simulations of varying hip loading conditions can be used to study the architecture of the femoral neck. The strength of 19 pairs of human femora was measured ex vivo using nonlinear hvFE models derived from high-resolution peripheral QCT scans (voxel size: 30.3 µm). Standing and side-backwards falling loads were modeled. Quasi-static mechanical tests were performed on 20 bones for comparison. Associations of femur strength with volumetric bone mineral density (vBMD) or microstructural parameters of the femoral neck obtained from high-resolution QCT were compared between mechanical tests and simulations and between standing and falling loads. Proximal femur strength predictions by hvFE models were positively associated with the vBMD of the femoral neck (R² > 0.61, p < 0.001), as well as with its cortical thickness (R² > 0.27, p < 0.001), trabecular bone volume fraction (R² = 0.42, p < 0.001) and with the first two principal components of the femoral neck architecture (R² > 0.38, p < 0.001). Associations between femur strength and femoral neck microarchitecture were stronger for one-legged standing than for side-backwards falling. For both loading directions, associations between structural parameters and femur strength from hvFE models were in good agreement with those from mechanical tests. This suggests that hvFE models can reflect the load-direction-specific contribution of the femoral neck microarchitecture to femur strength.
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Affiliation(s)
- Gianluca Iori
- Berlin-Brandenburg Center for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Laura Peralta
- Laboratoire d'Imagerie Biomédicale, Sorbonne Universités, INSERM UMR S 1146, CNRS UMR, 7371, Paris, France; Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King's College London, London, UK
| | - Andreas Reisinger
- Division Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - Frans Heyer
- Department of Internal Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands; Department of Internal Medicine, VieCuri Medical Center, Venlo, the Netherlands
| | - Caroline Wyers
- Department of Internal Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands; Department of Internal Medicine, VieCuri Medical Center, Venlo, the Netherlands
| | - Joop van den Bergh
- Department of Internal Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands; Department of Internal Medicine, VieCuri Medical Center, Venlo, the Netherlands
| | - Dieter Pahr
- Division Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria; Institute for Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
| | - Kay Raum
- Berlin-Brandenburg Center for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
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Amini M, Reisinger A, Pahr DH. Influence of processing parameters on mechanical properties of a 3D-printed trabecular bone microstructure. J Biomed Mater Res B Appl Biomater 2020; 108:38-47. [PMID: 30893513 PMCID: PMC6916655 DOI: 10.1002/jbm.b.34363] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 01/25/2019] [Accepted: 02/27/2019] [Indexed: 01/29/2023]
Abstract
Natural bone microstructure has shown to be the most efficient choice for the bone scaffold design. However, there are several process parameters involved in the generation of a microCT-based 3D-printed (3DP) bone. In this study, the effect of selected parameters on the reproducibility of mechanical properties of a 3DP trabecular bone structure is investigated. MicroCT images of a distal radial sample were used to reconstruct a 3D ROI of trabecular bone. Nine tensile tests on bulk material and 54 compression tests on 8.2 mm cubic samples were performed (9 cases × 6 specimens/case). The effect of input-image resolution, STL mesh decimation, boundary condition, support material, and repetition parameters on the weight, elastic modulus, and strength were studied. The elastic modulus and the strength of bulk material showed consistent results (CV% = 9 and 6%, respectively). The weight, elastic modulus, and strength of the cubic samples showed small intragroup variation (average CV% = 1.2, 9, and 5.5%, respectively). All studied parameters had a significant effect on the outcome variables with less effect on the weight. Utmost care to every step of the 3DP process and involved parameters is required to be able to reach the desired mechanical properties in the final printed specimen. © 2019 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:38-47, 2020.
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Affiliation(s)
- Morteza Amini
- Institute for lightweight design and structural biomechanicsVienna University of Technology1060 ViennaAustria
- Department of Anatomy and BiomechanicsKarl Landsteiner University for Health Sciences3500 KremsAustria
| | - Andreas Reisinger
- Department of Anatomy and BiomechanicsKarl Landsteiner University for Health Sciences3500 KremsAustria
| | - Dieter H. Pahr
- Institute for lightweight design and structural biomechanicsVienna University of Technology1060 ViennaAustria
- Department of Anatomy and BiomechanicsKarl Landsteiner University for Health Sciences3500 KremsAustria
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Iori G, Schneider J, Reisinger A, Heyer F, Peralta L, Wyers C, Gräsel M, Barkmann R, Glüer CC, van den Bergh JP, Pahr D, Raum K. Correction: Large cortical bone pores in the tibia are associated with proximal femur strength. PLoS One 2019; 14:e0219443. [PMID: 31276564 PMCID: PMC6611664 DOI: 10.1371/journal.pone.0219443] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
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Iori G, Schneider J, Reisinger A, Heyer F, Peralta L, Wyers C, Gräsel M, Barkmann R, Glüer CC, van den Bergh JP, Pahr D, Raum K. Large cortical bone pores in the tibia are associated with proximal femur strength. PLoS One 2019; 14:e0215405. [PMID: 30995279 PMCID: PMC6469812 DOI: 10.1371/journal.pone.0215405] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 04/01/2019] [Indexed: 11/23/2022] Open
Abstract
Alterations of structure and density of cortical bone are associated with fragility fractures and can be assessed in vivo in humans at the tibia. Bone remodeling deficits in aging women have been recently linked to an increase in size of cortical pores. In this ex vivo study, we characterized the cortical microarchitecture of 19 tibiae from human donors (aged 69 to 94 years) to address, whether this can reflect impairments of the mechanical competence of the proximal femur, i.e., a major fracture site in osteoporosis. Scanning acoustic microscopy (12 μm pixel size) provided reference microstructural measurements at the left tibia, while the bone vBMD at this site was obtained using microcomputed tomography (microCT). The areal bone mineral density of both left and right femoral necks (aBMDneck) was measured by dual‐energy X‐ray absorptiometry (DXA), while homogenized nonlinear finite element models based on high-resolution peripheral quantitative computed tomography provided hip stiffness and strength for one-legged standing and sideways falling loads. Hip strength was associated with aBMDneck (r = 0.74 to 0.78), with tibial cortical thickness (r = 0.81) and with measurements of the tibial cross-sectional geometry (r = 0.48 to 0.73) of the same leg. Tibial vBMD was associated with hip strength only for standing loads (r = 0.59 to 0.65). Cortical porosity (Ct.Po) of the tibia was not associated with any of the femoral parameters. However, the proportion of Ct.Po attributable to large pores (diameter > 100 μm) was associated with hip strength in both standing (r = -0.61) and falling (r = 0.48) conditions. When added to aBMDneck, the prevalence of large pores could explain up to 17% of the femur ultimate force. In conclusion, microstructural characteristics of the tibia reflect hip strength as well as femoral DXA, but it remains to be tested whether such properties can be measured in vivo.
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Affiliation(s)
- Gianluca Iori
- Berlin-Brandenburg Center for Regenerative Therapies, Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Johannes Schneider
- Berlin-Brandenburg Center for Regenerative Therapies, Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Andreas Reisinger
- Division Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - Frans Heyer
- Department of Internal Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Internal Medicine, VieCuri Medical Center, Venlo, The Netherlands
| | - Laura Peralta
- Laboratoire d’Imagerie Biomédicale, Sorbonne Universités, INSERM UMR S 1146, CNRS UMR 7371, Paris, France
- Department of Biomedical Engineering, School of Biomedical Engineering & Imaging Sciences, King’s College London, London, United Kingdom
| | - Caroline Wyers
- Department of Internal Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Internal Medicine, VieCuri Medical Center, Venlo, The Netherlands
| | - Melanie Gräsel
- Sektion Biomedizinische Bildgebung, Klinik für Radiologie und Neuroradiologie, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Reinhard Barkmann
- Sektion Biomedizinische Bildgebung, Klinik für Radiologie und Neuroradiologie, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Claus C. Glüer
- Sektion Biomedizinische Bildgebung, Klinik für Radiologie und Neuroradiologie, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - J. P. van den Bergh
- Department of Internal Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Internal Medicine, VieCuri Medical Center, Venlo, The Netherlands
| | - Dieter Pahr
- Division Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria
- Institute for Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
| | - Kay Raum
- Berlin-Brandenburg Center for Regenerative Therapies, Charité –Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
- * E-mail:
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Benca E, Reisinger A, Patsch JM, Hirtler L, Synek A, Stenicka S, Windhager R, Mayr W, Pahr DH. Effect of simulated metastatic lesions on the biomechanical behavior of the proximal femur. J Orthop Res 2017; 35:2407-2414. [PMID: 28240373 DOI: 10.1002/jor.23550] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 02/21/2017] [Indexed: 02/04/2023]
Abstract
Pathologic fractures of femora in patients with metastatic cancer are associated with high morbidity and mortality. Prediction of impending fractures is based on unspecific clinical criteria or past clinician's experience, which leads to underestimation or overtreatment. The aim of this study was to investigate the effect of the site of metastatic lesions on biomechanical behavior of the proximal femur. Sixteen pairs of human femora were scanned with quantitative computed tomography (QCT) to asses bone mineral density. One femur of each pair remained intact while a defined lesion was reamed out in either the superolateral or inferomedial portion of the femoral neck of the contralateral femur. All femora were loaded in a mechanical test setup mimicking one-legged stance and stiffness, failure load, and fracture location were determined. In the biomechanical experiments the superolateral lesion and the inferomedial lesion caused a stiffness reduction of 19% and 66%, respectively. The average failure load was 40% and 75% lower for specimens with the superolateral (4.53 ± 1.56 kN) and inferomedial (1.89 ± 1.73 kN) lesions, respectively, compared to intact specimens (7.66 ± 3.34 kN). Lesions in the femoral neck led to reduction in both stiffness and failure load of the proximal femur. Furthermore, the site of the lesion had a large effect on the magnitude of the reduction in biomechanical properties. The presented data emphasize the importance of differentiating between locations of the lesion in pathologic fracture prediction of the metastatic femur and underline the insufficient accuracy of current predictive guidelines. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2407-2414, 2017.
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Affiliation(s)
- Emir Benca
- Department of Orthopaedic Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Andreas Reisinger
- Institute for Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
| | - Janina M Patsch
- Department of Radiology, Medical University of Vienna, Vienna, Austria
| | - Lena Hirtler
- Center for Anatomy and Cell Biology, Department of Anatomy, Medical University of Vienna, Vienna, Austria
| | - Alexander Synek
- Institute for Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
| | - Sandra Stenicka
- Department of Orthopaedic Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Reinhard Windhager
- Department of Orthopaedic Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Winfried Mayr
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Dieter H Pahr
- Institute for Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria
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Cejka D, Parada-Rodriguez D, Pichler S, Marculescu R, Kramer I, Kneissel M, Gross T, Reisinger A, Pahr D, Monier-Faugere MC, Haas M, Malluche HH. Only minor differences in renal osteodystrophy features between wild-type and sclerostin knockout mice with chronic kidney disease. Kidney Int 2016; 90:828-34. [PMID: 27528549 PMCID: PMC5530366 DOI: 10.1016/j.kint.2016.06.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 06/14/2016] [Accepted: 06/16/2016] [Indexed: 11/17/2022]
Abstract
Renal osteodystrophy affects the majority of patients with advanced chronic kidney disease (CKD) and is characterized by progressive bone loss. This study evaluated the effects of sclerostin knockout on bone in a murine model of severe, surgically induced CKD in both sclerostin knockout and wild-type mice. Mice of both genotypes with normal kidney function served as controls. Tibiae were analyzed using micro-computed tomography, and lumbar vertebrae were analyzed by histomorphometry. Results were tested for statistical significance by 2-way ANOVA to investigate whether bone of the knockout mice reacted differently to CKD compared with bone of wild-type mice. In the tibiae, there was no difference after creation of CKD between wild-type and knockout animals for cortical thickness or cross-sectional moment of inertia. Increases in cortical porosity induced by CKD differed significantly between genotypes in the tibial metaphysis but not in the diaphysis. In the trabecular compartment, no difference in reaction to CKD between genotypes was found for bone volume, trabecular number, trabecular thickness, and trabecular separation. In the lumbar vertebrae, significant differences in response to CKD between wild-type and knockout mice were seen for both bone volume and trabecular thickness. Osteoblast parameters did not differ significantly, whereas osteoclast numbers significantly increased in the wild-type but significantly decreased in knockout mice with CKD. No differences in response to CKD between genotypes were found for bone formation rate or mineral apposition rate. Thus, complete absence of sclerostin has only minor effects on CKD-induced bone loss in mice.
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Affiliation(s)
- Daniel Cejka
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria.
| | - Diego Parada-Rodriguez
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria
| | - Stefanie Pichler
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria
| | - Rodrig Marculescu
- Department of Laboratory Medicine, Medical University Vienna, Austria
| | - Ina Kramer
- Muscoloskeletal Disease Area, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Michaela Kneissel
- Muscoloskeletal Disease Area, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Thomas Gross
- Institute of Lightweight Design and Structural Biomechanics, Vienna University of Technology, Austria
| | - Andreas Reisinger
- Institute of Lightweight Design and Structural Biomechanics, Vienna University of Technology, Austria
| | - Dieter Pahr
- Institute of Lightweight Design and Structural Biomechanics, Vienna University of Technology, Austria
| | - Marie-Claude Monier-Faugere
- Division of Nephrology, Bone and Mineral Metabolism, Department of Internal Medicine, University of Kentucky, Lexington, Kentucky, USA
| | - Martin Haas
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria
| | - Hartmut H Malluche
- Division of Nephrology, Bone and Mineral Metabolism, Department of Internal Medicine, University of Kentucky, Lexington, Kentucky, USA
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Farahmand P, Marin F, Hawkins F, Möricke R, Ringe JD, Glüer CC, Papaioannou N, Minisola S, Martínez G, Nolla JM, Niedhart C, Guañabens N, Nuti R, Martín-Mola E, Thomasius F, Peña J, Graeff C, Kapetanos G, Petto H, Gentzel A, Reisinger A, Zysset PK. Early changes in biochemical markers of bone formation during teriparatide therapy correlate with improvements in vertebral strength in men with glucocorticoid-induced osteoporosis. Osteoporos Int 2013; 24:2971-81. [PMID: 23740422 PMCID: PMC3838582 DOI: 10.1007/s00198-013-2379-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 04/23/2013] [Indexed: 01/19/2023]
Abstract
UNLABELLED Changes of the bone formation marker PINP correlated positively with improvements in vertebral strength in men with glucocorticoid-induced osteoporosis (GIO) who received 18-month treatment with teriparatide, but not with risedronate. These results support the use of PINP as a surrogate marker of bone strength in GIO patients treated with teriparatide. INTRODUCTION To investigate the correlations between biochemical markers of bone turnover and vertebral strength estimated by finite element analysis (FEA) in men with GIO. METHODS A total of 92 men with GIO were included in an 18-month, randomized, open-label trial of teriparatide (20 μg/day, n = 45) and risedronate (35 mg/week, n = 47). High-resolution quantitative computed tomography images of the 12th thoracic vertebra obtained at baseline, 6 and 18 months were converted into digital nonlinear FE models and subjected to anterior bending, axial compression and torsion. Stiffness and strength were computed for each model and loading mode. Serum biochemical markers of bone formation (amino-terminal-propeptide of type I collagen [PINP]) and bone resorption (type I collagen cross-linked C-telopeptide degradation fragments [CTx]) were measured at baseline, 3 months, 6 months and 18 months. A mixed-model of repeated measures analysed changes from baseline and between-group differences. Spearman correlations assessed the relationship between changes from baseline of bone markers with FEA variables. RESULTS PINP and CTx levels increased in the teriparatide group and decreased in the risedronate group. FEA-derived parameters increased in both groups, but were significantly higher at 18 months in the teriparatide group. Significant positive correlations were found between changes from baseline of PINP at 3, 6 and 18 months with changes in FE strength in the teriparatide-treated group, but not in the risedronate group. CONCLUSIONS Positive correlations between changes in a biochemical marker of bone formation and improvement of biomechanical properties support the use of PINP as a surrogate marker of bone strength in teriparatide-treated GIO patients.
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Affiliation(s)
- P Farahmand
- West German Osteoporosis Centre, Klinikum Leverkusen, University of Cologne, Am Gesundheitspark 11, 51375, Leverkusen, Germany,
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Glüer CC, Marin F, Ringe JD, Hawkins F, Möricke R, Papaioannu N, Farahmand P, Minisola S, Martínez G, Nolla JM, Niedhart C, Guañabens N, Nuti R, Martín-Mola E, Thomasius F, Kapetanos G, Peña J, Graeff C, Petto H, Sanz B, Reisinger A, Zysset PK. Comparative effects of teriparatide and risedronate in glucocorticoid-induced osteoporosis in men: 18-month results of the EuroGIOPs trial. J Bone Miner Res 2013; 28:1355-68. [PMID: 23322362 PMCID: PMC3708101 DOI: 10.1002/jbmr.1870] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 12/10/2012] [Accepted: 12/26/2012] [Indexed: 11/11/2022]
Abstract
Data on treatment of glucocorticoid-induced osteoporosis (GIO) in men are scarce. We performed a randomized, open-label trial in men who have taken glucocorticoids (GC) for ≥3 months, and had an areal bone mineral density (aBMD) T-score ≤ -1.5 standard deviations. Subjects received 20 μg/d teriparatide (n = 45) or 35 mg/week risedronate (n = 47) for 18 months. Primary objective was to compare lumbar spine (L1 -L3 ) BMD measured by quantitative computed tomography (QCT). Secondary outcomes included BMD and microstructure measured by high-resolution QCT (HRQCT) at the 12th thoracic vertebra, biomechanical effects for axial compression, anterior bending, and axial torsion evaluated by finite element (FE) analysis from HRQCT data, aBMD by dual X-ray absorptiometry, biochemical markers, and safety. Computed tomography scans were performed at 0, 6, and 18 months. A mixed model repeated measures analysis was performed to compare changes from baseline between groups. Mean age was 56.3 years. Median GC dose and duration were 8.8 mg/d and 6.4 years, respectively; 39.1% of subjects had a prevalent fracture, and 32.6% received prior bisphosphonate treatment. At 18 months, trabecular BMD had significantly increased for both treatments, with significantly greater increases with teriparatide (16.3% versus 3.8%; p = 0.004). HRQCT trabecular and cortical variables significantly increased for both treatments with significantly larger improvements for teriparatide for integral and trabecular BMD and bone surface to volume ratio (BS/BV) as a microstructural measure. Vertebral strength increases at 18 months were significant in both groups (teriparatide: 26.0% to 34.0%; risedronate: 4.2% to 6.7%), with significantly higher increases in the teriparatide group for all loading modes (0.005 < p < 0.015). Adverse events were similar between groups. None of the patients on teriparatide but five (10.6%) on risedronate developed new clinical fractures (p = 0.056). In conclusion, in this 18-month trial in men with GIO, teriparatide showed larger improvements in spinal BMD, microstructure, and FE-derived strength than risedronate.
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Affiliation(s)
- Claus-C Glüer
- Sektion Biomedizinische Bildgebung, Klinik für Diagnostische Radiologie, Universitätsklinikum Schleswig-Holstein, Kiel, Germany. ‐kiel.de
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Graeff C, Marin F, Petto H, Kayser O, Reisinger A, Peña J, Zysset P, Glüer CC. High resolution quantitative computed tomography-based assessment of trabecular microstructure and strength estimates by finite-element analysis of the spine, but not DXA, reflects vertebral fracture status in men with glucocorticoid-induced osteoporosis. Bone 2013; 52:568-77. [PMID: 23149277 DOI: 10.1016/j.bone.2012.10.036] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 10/07/2012] [Accepted: 10/31/2012] [Indexed: 11/25/2022]
Abstract
High-resolution quantitative computed tomography (HRQCT)-based analysis of spinal bone density and microstructure, finite element analysis (FEA), and DXA were used to investigate the vertebral bone status of men with glucocorticoid-induced osteoporosis (GIO). DXA of L1-L3 and total hip, QCT of L1-L3, and HRQCT of T12 were available for 73 men (54.6±14.0years) with GIO. Prevalent vertebral fracture status was evaluated on radiographs using a semi-quantitative (SQ) score (normal=0 to severe fracture=3), and the spinal deformity index (SDI) score (sum of SQ scores of T4 to L4 vertebrae). Thirty-one (42.4%) subjects had prevalent vertebral fractures. Cortical BMD (Ct.BMD) and thickness (Ct.Th), trabecular BMD (Tb.BMD), apparent trabecular bone volume fraction (app.BV/TV), and apparent trabecular separation (app.Tb.Sp) were analyzed by HRQCT. Stiffness and strength of T12 were computed by HRQCT-based nonlinear FEA for axial compression, anterior bending and axial torsion. In logistic regressions adjusted for age, glucocorticoid dose and osteoporosis treatment, Tb.BMD was most closely associated with vertebral fracture status (standardized odds ratio [sOR]: Tb.BMD T12: 4.05 [95% CI: 1.8-9.0], Tb.BMD L1-L3: 3.95 [1.8-8.9]). Strength divided by cross-sectional area for axial compression showed the most significant association with spine fracture status among FEA variables (2.56 [1.29-5.07]). SDI was best predicted by a microstructural model using Ct.Th and app.Tb.Sp (r(2)=0.57, p<0.001). Spinal or hip DXA measurements did not show significant associations with fracture status or severity. In this cross-sectional study of males with GIO, QCT, HRQCT-based measurements and FEA variables were superior to DXA in discriminating between patients of differing prevalent vertebral fracture status. A microstructural model combining aspects of cortical and trabecular bone reflected fracture severity most accurately.
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Affiliation(s)
- Christian Graeff
- Sektion Biomedizinische Bildgebung, Klinik für Diagnostische Radiologie, Universitätsklinikum Schleswig-Holstein, Kiel, Germany.
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Reisinger A, Trapp N, Knapp C, Himmel D, Breher F, Rüegger H, Krossing I. SilverâEthene Complexes [Ag(η2-C2H4)n][Al(ORF)4] withn=1, 2, 3 (RF=Fluorine-Substituted Group). Chemistry 2009; 15:9505-20. [PMID: 19693753 DOI: 10.1002/chem.200900100] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Andreas Reisinger
- Albert-Ludwigs-Universität Freiburg, Institut für Anorganische und Allgemeine Chemie and Freiburger Materialforschungszentrum (FMF), Albertstr. 21, 79104 Freiburg, Germany
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Reisinger A, Trapp N, Krossing I, Altmannshofer S, Herz V, Presnitz M, Scherer W. Homoleptic silver(I) acetylene complexes. Angew Chem Int Ed Engl 2008; 46:8295-8. [PMID: 17943934 DOI: 10.1002/anie.200702688] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Andreas Reisinger
- Institut für Anorganische und Allgemeine Chemie, Albert-Ludwigs-Universität Freiburg, Albertstrasse 21, 79104 Freiburg, Germany
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Reisinger A, Trapp N, Krossing I, Altmannshofer S, Herz V, Presnitz M, Scherer W. Homoleptische Silber(I)-Acetylen-Komplexe. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200702688] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Reisinger A, Trapp N, Krossing I, Altmannshofer S, Herz V, Presnitz M, Scherer W. Innentitelbild: Homoleptische Silber(I)-Acetylen-Komplexe (Angew. Chem. 43/2007). Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200790216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Reisinger A, Trapp N, Krossing I, Altmannshofer S, Herz V, Presnitz M, Scherer W. Inside Cover: Homoleptic Silver(I) Acetylene Complexes (Angew. Chem. Int. Ed. 43/2007). Angew Chem Int Ed Engl 2007. [DOI: 10.1002/anie.200790216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Affiliation(s)
- Andreas Reisinger
- Institut für Anorganische und Allgemeine Chemie, Albert Ludwigs Universität Freiburg, Albertstrasse 21, D-79104 Freiburg, Germany
| | - Nils Trapp
- Institut für Anorganische und Allgemeine Chemie, Albert Ludwigs Universität Freiburg, Albertstrasse 21, D-79104 Freiburg, Germany
| | - Ingo Krossing
- Institut für Anorganische und Allgemeine Chemie, Albert Ludwigs Universität Freiburg, Albertstrasse 21, D-79104 Freiburg, Germany
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Affiliation(s)
- Gustavo Santiso-Quiñones
- Albert-Ludwig Universität Freiburg. Institut für Anorganische und Analytische Chemie, Albertstr. 21, 79104, Freiburg, Germany.
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Krossing I, Reisinger A. Chemistry with weakly-coordinating fluorinated alkoxyaluminate anions: Gas phase cations in condensed phases? Coord Chem Rev 2006. [DOI: 10.1016/j.ccr.2005.10.023] [Citation(s) in RCA: 188] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Reisinger A, Himmel D, Krossing I. AgOC(CF3)3 und AgOSiiPr3 – Synthese und Charakterisierung eines donorfreien Silber(I)-Alkoxids und -Siloxids. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200600805] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Reisinger A, Himmel D, Krossing I. AgOC(CF3)3 and AgOSiiPr3—Synthesis and Characterization of a Donor-Free Silver(I) Alkoxide and Silyl Oxide. Angew Chem Int Ed Engl 2006; 45:6997-7000. [PMID: 16991158 DOI: 10.1002/anie.200600805] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Andreas Reisinger
- Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität, 79104 Freiburg, Germany
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Krossing I, Reisinger A. Perfluorinated Alkoxyaluminate Salts of Cationic Brønsted Acids: Synthesis, Structure, and Characterization of [H(OEt2)2][Al{OC(CF3)3}4] and[H(THF)2][Al{OC(CF3)3}4]. Eur J Inorg Chem 2005. [DOI: 10.1002/ejic.200400436] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Krossing I, Reisinger A. A Stable Salt of the Tris(ethene)silver Cation: Structure and Characterization of[Ag(η2-C2H4)3]+[Al{OC(CF3)3}4]−. Angew Chem Int Ed Engl 2003. [DOI: 10.1002/ange.200390662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Krossing I, Reisinger A. A Stable Salt of the Tris(ethene)silver Cation: Structure and Characterization of[Ag(η2-C2H4)3]+[Al{OC(CF3)3}4]−. Angew Chem Int Ed Engl 2003. [DOI: 10.1002/anie.200390635] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Krossing I, Reisinger A. A Stable Salt of the Tris(ethene)silver Cation: Structure and Characterization of[Ag(η2-C2H4)3]+[Al{OC(CF3)3}4]−. Angew Chem Int Ed Engl 2003. [DOI: 10.1002/ange.200352080] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Krossing I, Reisinger A. A Stable Salt of the Tris(ethene)silver Cation: Structure and Characterization of[Ag(η2-C2H4)3]+[Al{OC(CF3)3}4]−. Angew Chem Int Ed Engl 2003; 42:5725-8. [PMID: 14661206 DOI: 10.1002/anie.200352080] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Ingo Krossing
- Universität Karlsruhe, Institut für Anorganische Chemie, Engesserstrasse Geb. 30.45, 76128 Karlsruhe, Germany.
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Lemmens M, Reisinger A, Bürstmayr H, Ruckenbauer P. BREEDING FOR HEAD BLIGHT (FUSARIUM SPP.) RESISTANCE IN WHEAT: DEVELOPMENT OF A MYCOTOXIN-BASED SELECTION METHOD OF SEEDLINGS. ACTA ACUST UNITED AC 1994. [DOI: 10.17660/actahortic.1994.355.25] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
A number of analysis techniques aimed at determining the characteristics of optical guided waves propagating in lossy structures are examined. The exact theory is used as a guide to assess the validity of several approximate methods based on two basic approaches: (a) geometrical optics and (b) perturbation calculations. The limitations of the conventional perturbation techniques are specified. We present a generalized procedure that permits an accurate description of metal boundaries at optical frequencies. In this case, TM modes differ from their TE counterparts by a field buildup near conducting walls and by the existence of an additional surface plasma mode. The dependence of attenuation coefficients on film thickness and mode order are discussed. The use of low-index dielectric buffers to reduce ohmic losses is considered. It is found that, with increasing buffer thickness, TM(N) modes undergo a continuous transformation to become TM(N+1).
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