Publications by authors named "Dieter H Pahr"

62 Publications

Femoral strength can be predicted from 2D projections using a 3D statistical deformation and texture model with finite element analysis.

Med Eng Phys 2021 Jul 24;93:72-82. Epub 2021 May 24.

Institut für Leichtbau und Struktur-Biomechanik, TU-Wien, Vienna, Austria; Karl Landsteiner University of Health Sciences, Krems, Austria. Electronic address:

Ultimate force of the proximal human femur can be predicted using Finite Element Analysis (FEA), but the models rely on 3D computed tomography images. Landmark-based statistical appearance models (SAM) and B-Spline transformation-based statistical deformation models (SDM) have been used to estimate 3D images from 2D projections, which facilitates model generation and reduces the radiation dose. However, there is no literature on the accuracy of SDM-based FEA models of bones with respect to experimental results. In this study, a methodology for an enhanced SDM with textural information is presented. The statistical deformation and texture models (SDTMs) are based on a set of 37 quantitative CT (QCT) images. They were used to estimate 3D images from two or one projections of the set in a leave-one-out setup. These estimations where then used to create FEA models. The ultimate force predicted by FEA models estimated from two or one projection using the SDTMs were compared to the experimental ultimate force from a previous study on the same femora and to the results of standard QCT-based FEA models. High correlations between predictions and experimental measurements were found for FEA models reconstructed from 2D projections with R=0.835 when based on two projections and R=0.724 when using one projection. The correlations were comparable to those reached with standard QCT-based FE-models with the experimental results (R=0.795). This study shows the high potential of SDTM-based 3D image reconstruction and FEA modelling from 2D projections to predict femoral ultimate force.
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http://dx.doi.org/10.1016/j.medengphy.2021.05.012DOI Listing
July 2021

Effects of anti-resorptive treatment on the material properties of individual canine trabeculae in cyclic tensile tests.

Bone 2021 Sep 1;150:115995. Epub 2021 May 1.

Institute of Lightweight Design and Structural Biomechanics, TU Wien, Gumpendorfer Straße 7, 1060 Vienna, Austria. Electronic address:

Osteoporosis is defined as a decrease of bone mass and strength, as well as an increase in fracture risk. It is conventionally treated with antiresorptive drugs, such as bisphosphonates (BPs) and selective estrogen receptor modulators (SERMs). Although both drug types successfully decrease the risk of bone fractures, their effect on bone mass and strength is different. For instance, BP treatment causes an increase of bone mass, stiffness and strength of whole bones, whereas SERM treatment causes only small (4%) increases of bone mass, but increased bone toughness. Such improved mechanical behavior of whole bones can be potentially related to the bone mass, bone structure or material changes. While bone mass and architecture have already been investigated previously, little is known about the mechanical behavior at the tissue/material level, especially of trabecular bone. As such, the goal of the work presented here was to fill this gap by performing cyclic tensile tests in a wet, close to physiologic environment of individual trabeculae retrieved from the vertebrae of beagle dogs treated with alendronate (a BP), raloxifene (a SERM) or without treatments. Identification of material properties was performed with a previously developed rheological model and of mechanical properties via fitting of envelope curves. Additionally, tissue mineral density (TMD) and microdamage formation were analyzed. Alendronate treatment resulted in a higher trabecular tissue stiffness and strength, associated with higher levels of TMD. In contrast, raloxifene treatment caused a higher trabecular toughness, pre-dominantly in the post-yield region. Microdamage formation during testing was not affected by either anti-resorptive treatment regimens. These findings highlight that the improved mechanical behavior of whole bones after anti-resorptive treatment is at least partly caused by improved material properties, with different mechanisms for alendronate and raloxifene. This study further shows the power of performing a mechanical characterization of trabecular bone at the level of individual trabeculae for better understanding of clinically relevant mechanical behavior of bone.
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http://dx.doi.org/10.1016/j.bone.2021.115995DOI Listing
September 2021

Comparison of Thiel preserved, fresh human, and animal liver tissue in terms of mechanical properties.

Ann Anat 2021 Jul 6;236:151717. Epub 2021 Mar 6.

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, University of Technology Vienna, Getreidemarkt 9, 1060 Wien, Austria. Electronic address:

Background: In medical training and research fresh human tissue is often replaced by preserved human or fresh animal tissue, due to availability and ethical reasons. Newer preservation approaches, such as the Thiel method, promise more realistic mechanical properties than conventional formaldehyde fixation. Concerning animal substitute material, porcine and bovine tissue is often chosen, as it is easily obtainable and certain similarity to human tissue is assumed. However, it has not been thoroughly investigated how Thiel preservation changes non-linear and viscoelastic behaviour of soft organ tissues. Furthermore, differences in these properties between animal tissue and human tissue have not been previously corroborated.

Methods: We conducted ramp and relaxation tensile tests on fresh human and Thiel preserved hepatic tissue, extracting strain-specific elastic moduli, and viscoelastic properties. The results for fresh human liver were then compared to corresponding results for Thiel preserved liver, as well as previously published results for porcine and bovine liver.

Results: Our results showed that Thiel preservation seems to be associated with increased stiffness as well as decreased viscoelastic damping behaviour. Porcine liver was stiffer than human liver with similar viscoelastic properties. Bovine liver exhibited similar stiffness as human liver, however lower viscoelastic damping.

Conclusions: The differences between human and animal liver tissue, concerning their mechanical properties, can be explained by their characteristic histology. Changes in mechanical properties due to Thiel preservation might stem from altered protein cross-linking and dehydration. The results illustrate that appropriate materials for medical training systems must be selected based on which mechanical properties are relevant for the respective application.
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http://dx.doi.org/10.1016/j.aanat.2021.151717DOI Listing
July 2021

Towards optimization of volar plate fixations of distal radius fractures: Using finite element analyses to reduce the number of screws.

Clin Biomech (Bristol, Avon) 2021 02 13;82:105272. Epub 2021 Jan 13.

Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria; Department of Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria.

Background: Using fewer distal screws in volar plate fixation of distal radius fractures could reduce treatment costs and complications. However, there is currently no consensus on the ideal screw configuration, likely due to experimental limitations and its subject-specific nature. In this study, finite element analysis was used to investigate (1) if reducing the number of screws is biomechanically feasible and (2) if an optimal screw configuration is subject-specific.

Methods: Validated subject-specific finite element models of 16 human radii with extra articular distal radius fractures and volar plate fixation with six distal screws were used as a baseline. 41 additional configurations with three to six distal screws were simulated for each subject. Axial stiffness and peri-implant strains around the distal screws were evaluated. Subject-specific optimum configurations were determined using a lower bound for the axial stiffness and minimizing peri-implant strains.

Findings: Even using three distal screws led to only minor deterioration of the biomechanical properties in the best configuration (axial stiffness: -11.2%, peri-implant strains: -35.0%), but a considerable deterioration in the worst configuration (axial stiffness: -46.2%, peri-implant strains: +112.4%). The optimization showed that the ideal screw configuration is subject-specific and on average 1.9 screws could be saved based on the herein used optimization criterion.

Interpretation: This study highlights that not only how many, but which screws are used in volar plate fixation of distal radius fractures is critical. Using a patient-specific selection of distal screws bears potential to save costs and reduce complications.
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http://dx.doi.org/10.1016/j.clinbiomech.2021.105272DOI Listing
February 2021

Prediction of the Inelastic Behaviour of Radius Segments: Damage-based Nonlinear Micro Finite Element Simulation vs Pistoia Criterion.

J Biomech 2021 02 2;116:110205. Epub 2021 Jan 2.

Institute of Lightweight Design and Structural Biomechanics, TU Wien, Austria; Division Biomechanics, Karl Landsteiner University, Austria.

The Pistoia criterion (PC) is widely used to estimate the failure load of distal radius segments based on linear micro Finite Element (μFE) analyses. The advantage of the PC is that a simple strain-threshold and a tissue volume fraction can be used to predict failure properties. In this study, the PC is compared to materially nonlinear μFE analyses, where the bone tissue is modelled as an elastic, damageable material. The goal was to investigate for which outcomes the PC is sufficient and when a nonlinear (NL) simulation is required. Three types of simulation results were compared: (1) prediction of the failure load, (2) load sharing of cortical and trabecular regions, and (3) distribution of local damaged/overstrained tissue at the maximum sustainable load. The failure load obtained experimentally could be predicted well with both the PC and the NL simulations using linear regression. Although the PC strongly overestimated the failure load, it was sufficient to predict adequately normalized apparent results. An optimised PC (oPC) was proposed which uses experimental data to calibrate the individual volume of overstrained tissue. The main areas of local over-straining predicted by the oPC were the same as estimated by the NL simulation, although the oPC predicted more diffuse regions. However, the oPC relied on an individual calibration requiring the experimental failure load while the NL simulation required no a priori knowledge of the experimental failure load.
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http://dx.doi.org/10.1016/j.jbiomech.2020.110205DOI Listing
February 2021

Reply to Haeusler et al.: Internal structure of the femur provides robust evidence for locomotor and taxonomic diversity at Sterkfontein.

Proc Natl Acad Sci U S A 2020 11 20;117(46):28570-28571. Epub 2020 Oct 20.

Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury CT2 7NR, United Kingdom.

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http://dx.doi.org/10.1073/pnas.2016647117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7682416PMC
November 2020

A Review on Recent Advances in the Constitutive Modeling of Bone Tissue.

Curr Osteoporos Rep 2020 Dec 17;18(6):696-704. Epub 2020 Oct 17.

Department of Anatomy und Biomechanics, Karl Landsteiner University of Health Sciences, Krems, Austria.

Purpose Of Review: Image-based finite element analysis (FEA) to predict and understand the biomechanical response has become an essential methodology in musculoskeletal research. An important part of such simulation models is the constitutive material model of which recent advances are summarized in this review.

Recent Findings: The review shows that existing models from other fields were introduced, such as cohesion zone (cortical bone) or phase-field models (trabecular bone). Some progress has been made in describing cortical bone involving physical mechanisms such as microcracks. Problems with validations at different length scales remain a problem. The improvement of recent constitutive models is partially obscured by uncertainties that affect overall predictions, such as image quality and calibration or boundary conditions. Nevertheless, in vivo CT-based FEA simulations based on a sophisticated constitutive behavior are a very valuable tool for clinical-related osteoporosis research.
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http://dx.doi.org/10.1007/s11914-020-00631-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7732794PMC
December 2020

Hyperelastic and viscoelastic characterization of hepatic tissue under uniaxial tension in time and frequency domain.

J Mech Behav Biomed Mater 2020 12 24;112:104038. Epub 2020 Aug 24.

Department Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, 3500 Krems an der Donau, Austria. Electronic address:

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 E, 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 (E∼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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http://dx.doi.org/10.1016/j.jmbbm.2020.104038DOI Listing
December 2020

Effect of CT imaging on the accuracy of the finite element modelling in bone.

Eur Radiol Exp 2020 09 1;4(1):51. Epub 2020 Sep 1.

Institute of Lightweight Design and Structural Biomechanics, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria.

The finite element (FE) analysis is a highly promising tool to simulate the behaviour of bone. Skeletal FE models in clinical routine rely on the information about the geometry and bone mineral density distribution from quantitative computed tomography (CT) imaging systems. Several parameters in CT imaging have been reported to affect the accuracy of FE models. FE models of bone are exclusively developed in vitro under scanning conditions deviating from the clinical setting, resulting in variability of FE results (< 10%). Slice thickness and field of view had little effect on FE predicted bone behaviour (≤ 4%), while the reconstruction kernels showed to have a larger effect (≤ 20%). Due to large interscanner variations (≤ 20%), the translation from an experimental model into clinical reality is a critical step. Those variations are assumed to be mostly caused by different "black box" reconstruction kernels and the varying frequency of higher density voxels, representing cortical bone. Considering the low number of studies together with the significant effect of CT imaging on the finite element model outcome leading to high variability in the predicted behaviour, we propose further systematic research and validation studies, ideally preceding multicentre and longitudinal studies.
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http://dx.doi.org/10.1186/s41747-020-00180-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7458968PMC
September 2020

Correction to: A two‑layer elasto‑visco‑plastic rheological model for the material parameter identification of bone tissue.

Biomech Model Mechanobiol 2020 10;19(5):1977

Division Biomechanics, Department of Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria.

In the original publication of the article.
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http://dx.doi.org/10.1007/s10237-020-01356-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7502445PMC
October 2020

Comparison of different microCT-based morphology assessment tools using human trabecular bone.

Bone Rep 2020 Jun 4;12:100261. Epub 2020 May 4.

Institute for Lightweight Design and Structural Biomechanics, TU-Wien, Vienna, Austria.

MicroCT-based morphological parameters are often used to quantify the structural properties of trabecular bone. Various software tools are available for calculating these parameters. Studies that examine the comparability of their results are rare. Four different software tools were used to analyse a set of 701 microCT images from human trabecular bone samples. Bone volume to total volume (/), bone surface (), trabecular thickness (. .) and degree of anisotropy () were evaluated. / shows very low difference (-0.18 ± 0.15%). The difference in could be reduced below 5% if artificial cut surfaces are not included. . . and . . show differences of maximal -12% although the same theoretical background is used. is most critical with differences from 4.75 ± 3.70% (medtool vs. Scanco), over -38.61 ± 13.15% (BoneJ vs. Scanco), up to 80.52 ± 50.04% (medtool vs. BoneJ). Quantitative results should be considered with caution, especially when comparing different studies. Introducing standardization procedures and the disclosure of underlying algorithms and their respective implementations could improve this issue.
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http://dx.doi.org/10.1016/j.bonr.2020.100261DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7235944PMC
June 2020

The position of Australopithecus sediba within fossil hominin hand use diversity.

Nat Ecol Evol 2020 07 18;4(7):911-918. Epub 2020 May 18.

Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.

The human lineage is marked by a transition in hand use, from locomotion towards increasingly dexterous manipulation, concomitant with bipedalism. The forceful precision grips used by modern humans probably evolved in the context of tool manufacture and use, but when and how many times hominin hands became principally manipulative remains unresolved. We analyse metacarpal trabecular and cortical bone, which provide insight into behaviour during an individual's life, to demonstrate previously unrecognized diversity in hominin hand use. The metacarpals of the palm in Australopithecus sediba have trabecular morphology most like orangutans and consistent with locomotor power-grasping with the fingers, while that of the thumb is consistent with human-like manipulation. This internal morphology is the first record of behaviour consistent with a hominin that used its hand for both arboreal locomotion and human-like manipulation. This hand use is distinct from other fossil hominins in this study, including A. afarensis and A. africanus.
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http://dx.doi.org/10.1038/s41559-020-1207-5DOI Listing
July 2020

A two-layer elasto-visco-plastic rheological model for the material parameter identification of bone tissue.

Biomech Model Mechanobiol 2020 Dec 6;19(6):2149-2162. Epub 2020 May 6.

Division Biomechanics, Department of Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria.

The ability to measure bone tissue material properties plays a major role in diagnosis of diseases and material modeling. Bone's response to loading is complex and shows a viscous contribution to stiffness, yield and failure. It is also ductile and damaging and exhibits plastic hardening until failure. When performing mechanical tests on bone tissue, these constitutive effects are difficult to quantify, as only their combination is visible in resulting stress-strain data. In this study, a methodology for the identification of stiffness, damping, yield stress and hardening coefficients of bone from a single cyclic tensile test is proposed. The method is based on a two-layer elasto-visco-plastic rheological model that is capable of reproducing the specimens' pre- and postyield response. The model's structure enables for capturing the viscously induced increase in stiffness, yield, and ultimate stress and for a direct computation of the loss tangent. Material parameters are obtained in an inverse approach by optimizing the model response to fit the experimental data. The proposed approach is demonstrated by identifying material properties of individual bone trabeculae that were tested under wet conditions. The mechanical tests were conducted according to an already published methodology for tensile experiments on single trabeculae. As a result, long-term and instantaneous Young's moduli were obtained, which were on average 3.64 GPa and 5.61 GPa, respectively. The found yield stress of 16.89 MPa was lower than previous studies suggest, while the loss tangent of 0.04 is in good agreement. In general, the two-layer model was able to reproduce the cyclic mechanical test data of single trabeculae with an root-mean-square error of 2.91 ± 1.77 MPa. The results show that inverse rheological modeling can be of great advantage when multiple constitutive contributions shall be quantified based on a single mechanical measurement.
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http://dx.doi.org/10.1007/s10237-020-01329-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7603462PMC
December 2020

Evidence for habitual climbing in a Pleistocene hominin in South Africa.

Proc Natl Acad Sci U S A 2020 04 30;117(15):8416-8423. Epub 2020 Mar 30.

Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury CT2 7NR, United Kingdom.

Bipedalism is a defining trait of the hominin lineage, associated with a transition from a more arboreal to a more terrestrial environment. While there is debate about when modern human-like bipedalism first appeared in hominins, all known South African hominins show morphological adaptations to bipedalism, suggesting that this was their predominant mode of locomotion. Here we present evidence that hominins preserved in the Sterkfontein Caves practiced two different locomotor repertoires. The trabecular structure of a proximal femur (StW 522) attributed to exhibits a modern human-like bipedal locomotor pattern, while that of a geologically younger specimen (StW 311) attributed to either sp. or exhibits a pattern more similar to nonhuman apes, potentially suggesting regular bouts of both climbing and terrestrial bipedalism. Our results demonstrate distinct morphological differences, linked to behavioral differences between and later hominins in South Africa and contribute to the increasing evidence of locomotor diversity within the hominin clade.
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http://dx.doi.org/10.1073/pnas.1914481117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7165455PMC
April 2020

Quantifying tactile properties of liver tissue, silicone elastomers, and a 3D printed polymer for manufacturing realistic organ models.

J Mech Behav Biomed Mater 2020 04 13;104:103630. Epub 2020 Jan 13.

Division Biomechanics, Karl Landsteiner Private University, Dr.-Karl-Dorrek-Straße 30, 3500, Krems an der Donau, Austria.

In order to produce anatomical models that feel realistic to the touch, artificial materials need to be found that mimic tactile properties of biological tissues. The aim of this study was to provide a guideline for identifying materials that feel similar to biological tissues, based on a quantifiable and reproducible measure. For this, a testing procedure was developed to identify mechanical properties that contribute to tactility. Bovine and porcine liver tissues were compared to different silicone elastomers and a soft 3D printed polymer. Macroindentation was chosen to simulate the palpation of material cubes with loading occurring during actual finger and material interaction. Elastic behaviour was considered by conducting quasistatic loading and unloading for extracting contact stiffness S and equivalent spring stiffness k. Viscoelasticity was quantified by means of force relaxation for calculating loss tangent tanδ based on a Prony series approach. Furthermore, Shore 00 hardness H was measured with a hand-held durometer. For assessing how well materials mimicked liver in terms of tactile properties, a mean error of all measured properties was introduced, referred to as tactile similarity error Q. The 3D printed polymer exhibited the highest error (Q=100-150%), while the material with the lowest error - thus representing liver best - was a super-soft silicone elastomer (nominal hardness of 30 Shore Units) with Q~50%. In conclusion, a suitable material was found that best represented liver. However, the relatively high tactile similarity error, even for the best material tested, indicates that there is still room for improvement concerning material choice.
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http://dx.doi.org/10.1016/j.jmbbm.2020.103630DOI Listing
April 2020

Metacarpophalangeal joint loads during bonobo locomotion: model predictions versus proxies.

J R Soc Interface 2020 03 4;17(164):20200032. Epub 2020 Mar 4.

Animal Postcranial Evolution Laboratory, Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.

The analysis of internal trabecular and cortical bone has been an informative tool for drawing inferences about behaviour in extant and fossil primate taxa. Within the hand, metacarpal bone architecture has been shown to correlate well with primate locomotion; however, the extent of morphological differences across taxa is unexpectedly small given the variability in hand use. One explanation for this observation is that the activity-related differences in the joint loads acting on the bone are simply smaller than estimated based on commonly used proxies (i.e. external loading and joint posture), which neglect the influence of muscle forces. In this study, experimental data and a musculoskeletal finger model are used to test this hypothesis by comparing differences between climbing and knuckle-walking locomotion of captive bonobos () based on (i) joint load magnitude and direction predicted by the models and (ii) proxy estimations. The results showed that the activity-related differences in predicted joint loads are indeed much smaller than the proxies would suggest, with joint load magnitudes being almost identical between the two locomotor modes. Differences in joint load directions were smaller but still evident, indicating that joint load directions might be a more robust indicator of variation in hand use than joint load magnitudes. Overall, this study emphasizes the importance of including muscular forces in the interpretation of skeletal remains and promotes the use of musculoskeletal models for correct functional interpretations.
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http://dx.doi.org/10.1098/rsif.2020.0032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7115223PMC
March 2020

Efficient materially nonlinear [Formula: see text]FE solver for simulations of trabecular bone failure.

Biomech Model Mechanobiol 2020 Jun 20;19(3):861-874. Epub 2019 Nov 20.

Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria.

An efficient solver for large-scale linear [Formula: see text] simulations was extended for nonlinear material behavior. The material model included damage-based tissue degradation and fracture. The new framework was applied to 20 trabecular biopsies with a mesh resolution of [Formula: see text]. Suitable material parameters were identified based on two biopsies by comparison with axial tension and compression experiments. The good parallel performance and low memory footprint of the solver were preserved. Excellent correlation of the maximum apparent stress was found between simulations and experiments ([Formula: see text]). The development of local damage regions was observable due to the nonlinear nature of the simulations. A novel elasticity limit was proposed based on the local damage information. The elasticity limit was found to be lower than the 0.2% yield point. Systematic differences in the yield behavior of biopsies under apparent compression and tension loading were observed. This indicates that damage distributions could lead to more insight into the failure mechanisms of trabecular bone.
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http://dx.doi.org/10.1007/s10237-019-01254-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7203600PMC
June 2020

Musculoskeletal models of a human and bonobo finger: parameter identification and comparison to in vitro experiments.

PeerJ 2019 9;7:e7470. Epub 2019 Aug 9.

Institute of Lightweight Design and Structural Biomechanics, TU Wien, Vienna, Austria.

Introduction: Knowledge of internal finger loading during human and non-human primate activities such as tool use or knuckle-walking has become increasingly important to reconstruct the behaviour of fossil hominins based on bone morphology. Musculoskeletal models have proven useful for predicting these internal loads during human activities, but load predictions for non-human primate activities are missing due to a lack of suitable finger models. The main goal of this study was to implement both a human and a representative non-human primate finger model to facilitate comparative studies on metacarpal bone loading. To ensure that the model predictions are sufficiently accurate, the specific goals were: (1) to identify species-specific model parameters based on in vitro measured fingertip forces resulting from single tendon loading and (2) to evaluate the model accuracy of predicted fingertip forces and net metacarpal bone loading in a different loading scenario.

Materials & Methods: Three human and one bonobo () fingers were tested in vitro using a previously developed experimental setup. The cadaveric fingers were positioned in four static postures and load was applied by attaching weights to the tendons of the finger muscles. For parameter identification, fingertip forces were measured by loading each tendon individually in each posture. For the evaluation of model accuracy, the extrinsic flexor muscles were loaded simultaneously and both the fingertip force and net metacarpal bone force were measured. The finger models were implemented using custom Python scripts. Initial parameters were taken from literature for the human model and own dissection data for the bonobo model. Optimized model parameters were identified by minimizing the error between predicted and experimentally measured fingertip forces. Fingertip forces and net metacarpal bone loading in the combined loading scenario were predicted using the optimized models and the remaining error with respect to the experimental data was evaluated.

Results: The parameter identification procedure led to minor model adjustments but considerably reduced the error in the predicted fingertip forces (root mean square error reduced from 0.53/0.69 N to 0.11/0.20 N for the human/bonobo model). Both models remained physiologically plausible after the parameter identification. In the combined loading scenario, fingertip and net metacarpal forces were predicted with average directional errors below 6° and magnitude errors below 12%.

Conclusions: This study presents the first attempt to implement both a human and non-human primate finger model for comparative palaeoanthropological studies. The good agreement between predicted and experimental forces involving the action of extrinsic flexors-which are most relevant for forceful grasping-shows that the models are likely sufficiently accurate for comparisons of internal loads occurring during human and non-human primate manual activities.
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http://dx.doi.org/10.7717/peerj.7470DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6690335PMC
August 2019

QCT-based finite element prediction of pathologic fractures in proximal femora with metastatic lesions.

Sci Rep 2019 07 16;9(1):10305. Epub 2019 Jul 16.

Institute for Lightweight Design and Structural Biomechanics, TU Wien, 1060, Vienna, Austria.

Predicting pathologic fractures in femora with metastatic lesions remains a clinical challenge. Currently used guidelines are inaccurate, especially to predict non-impeding fractures. This study evaluated the ability of a nonlinear quantitative computed tomography (QCT)-based homogenized voxel finite element (hvFE) model to predict patient-specific pathologic fractures. The hvFE model was generated highly automated from QCT images of human femora. The femora were previously loaded in a one-legged stance setup in order to assess stiffness, failure load, and fracture location. One femur of each pair was tested in its intact state, while the contralateral femur included a simulated lesion on either the superolateral- or the inferomedial femoral neck. The hvFE model predictions of the stiffness (0.47 < R < 0.94), failure load (0.77 < R < 0.98), and exact fracture location (68%) were in good agreement with the experimental data. However, the model underestimated the failure load by a factor of two. The hvFE models predicted significant differences in stiffness and failure load for femora with superolateral- and inferomedial lesions. In contrast, standard clinical guidelines predicted identical fracture risk for both lesion sites. This study showed that the subject-specific QCT-based hvFE model could predict the effect of metastatic lesions on the biomechanical behaviour of the proximal femur with moderate computational time and high level of automation and could support treatment strategy in patients with metastatic bone disease.
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http://dx.doi.org/10.1038/s41598-019-46739-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6635505PMC
July 2019

Influence of processing parameters on mechanical properties of a 3D-printed trabecular bone microstructure.

J Biomed Mater Res B Appl Biomater 2020 01 20;108(1):38-47. Epub 2019 Mar 20.

Institute for lightweight design and structural biomechanics, Vienna University of Technology, 1060 Vienna, Austria.

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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http://dx.doi.org/10.1002/jbm.b.34363DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6916655PMC
January 2020

Trabecular architecture of the great ape and human femoral head.

J Anat 2019 05 21;234(5):679-693. Epub 2019 Feb 21.

Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.

Studies of femoral trabecular structure have shown that the orientation and volume of bone are associated with variation in loading and could be informative about individual joint positioning during locomotion. In this study, we analyse for the first time trabecular bone patterns throughout the femoral head using a whole-epiphysis approach to investigate how potential trabecular variation in humans and great apes relates to differences in locomotor modes. Trabecular architecture was analysed using microCT scans of Pan troglodytes (n = 20), Gorilla gorilla (n = 14), Pongo sp. (n = 5) and Homo sapiens (n = 12) in medtool 4.1. Our results revealed differences in bone volume fraction (BV/TV) distribution patterns, as well as overall trabecular parameters of the femoral head between great apes and humans. Pan and Gorilla showed two regions of high BV/TV in the femoral head, consistent with hip posture and loading during two discrete locomotor modes: knuckle-walking and climbing. Most Pongo specimens also displayed two regions of high BV/TV, but these regions were less discrete and there was more variability across the sample. In contrast, Homo showed only one main region of high BV/TV in the femoral head and had the lowest BV/TV, as well as the most anisotropic trabeculae. The Homo trabecular structure is consistent with stereotypical loading with a more extended hip compared with great apes, which is characteristic of modern human bipedalism. Our results suggest that holistic evaluations of femoral head trabecular architecture can reveal previously undetected patterns linked to locomotor behaviour in extant apes and can provide further insight into hip joint loading in fossil hominins and other primates.
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http://dx.doi.org/10.1111/joa.12957DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6481414PMC
May 2019

Inverse remodelling algorithm identifies habitual manual activities of primates based on metacarpal bone architecture.

Biomech Model Mechanobiol 2019 Apr 9;18(2):399-410. Epub 2018 Nov 9.

Institute of Lightweight Design and Structural Biomechanics, TU Wien, Getreidemarkt 9/BE, Vienna, Austria.

Previously, a micro-finite element (micro-FE)-based inverse remodelling method was presented in the literature that reconstructs the loading history of a bone based on its architecture alone. Despite promising preliminary results, it remains unclear whether this method is sensitive enough to detect differences of bone loading related to pathologies or habitual activities. The goal of this study was to test the sensitivity of the inverse remodelling method by predicting joint loading histories of metacarpal bones of species with similar anatomy but clearly distinct habitual hand use. Three groups of habitual hand use were defined using the most representative primate species: manipulation (human), suspensory locomotion (orangutan), and knuckle-walking locomotion (bonobo, chimpanzee, gorilla). Nine to ten micro-computed tomography scans of each species ([Formula: see text] in total) were used to create micro-FE models of the metacarpal head region. The most probable joint loading history was predicted by optimally scaling six load cases representing joint postures ranging from [Formula: see text] (extension) to [Formula: see text] (flexion). Predicted mean joint load directions were significantly different between knuckle-walking and non-knuckle-walking groups ([Formula: see text]) and in line with expected primary hand postures. Mean joint load magnitudes tended to be larger in species using their hands for locomotion compared to species using them for manipulation. In conclusion, this study shows that the micro-FE-based inverse remodelling method is sensitive enough to detect differences of joint loading related to habitual manual activities of primates and might, therefore, be useful for palaeoanthropologists to reconstruct the behaviour of extinct species and for biomedical applications such as detecting pathological joint loading.
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http://dx.doi.org/10.1007/s10237-018-1091-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6418057PMC
April 2019

A novel experimental design for the measurement of metacarpal bone loading and deformation and fingertip force.

PeerJ 2018 11;6:e5480. Epub 2018 Sep 11.

Animal Postcranial Evolution Lab, Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.

Background: Musculoskeletal and finite element modelling are often used to predict joint loading and bone strength within the human hand, but there is a lack of in vitro evidence of the force and strain experienced by hand bones.

Methods: This study presents a novel experimental setup that allows the positioning of a cadaveric digit in a variety of postures with the measurement of force and strain experienced by the third metacarpal. The setup allows for the measurement of fingertip force as well. We tested this experimental setup using three cadaveric human third digits in which the flexor tendons were loaded in two tendon pathways: (1) parallel to the metacarpal bone shaft, with bowstringing; (2) a semi-physiological condition in which the tendons were positioned closer to the bone shaft.

Results: There is substantial variation in metacarpal net force, metacarpal strain and fingertip force between the two tendon pathways. The net force acting on the metacarpal bone is oriented palmarly in the parallel tendon condition, causing tension along the dorsum of the metacarpal shaft, while the force increases and is oriented dorsally in the semi-physiological condition, causing compression of the dorsal metacarpal shaft. Fingertip force is also greater in the semi-physiological condition, implying a more efficient grip function. Inter-individual variation is observed in the radioulnar orientation of the force experienced by the metacarpal bone, the fingertip force, and the strain patterns on the metacarpal shaft.

Conclusion: This study demonstrates a new method for measuring force and strain experienced by the metacarpal, and fingertip force in cadaveric digits that can, in turn, inform computation models. Inter-individual variation in loads experienced by the third digit suggest that there are differences in joint contact and/or internal bone structure across individuals that are important to consider in clinical and evolutionary contexts.
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http://dx.doi.org/10.7717/peerj.5480DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6138040PMC
September 2018

Ontogeny and variability of trabecular bone in the chimpanzee humerus, femur and tibia.

Am J Phys Anthropol 2018 12 29;167(4):713-736. Epub 2018 Aug 29.

Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.

Objectives: Trabecular bone structure is known to be influenced by joint loading during life. However, many additional variables have the potential to contribute to trabecular bone structure of an adult individual, including age, sex, body size, genetics, and overall activity level. There is little research into intraspecific variability in trabecular bone and ontogeny of trabecular bone structure, especially in nonhuman primates.

Materials And Methods: This study investigates trabecular structure in adult and immature chimpanzees from a single population using high-resolution microcomputed tomographic scans of the proximal humerus, proximal femur, and distal tibia. Trabecular bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular spacing (Tb.Sp), and degree of anisotropy (DA) were quantified in specific regions of adult and immature chimpanzees, and color maps were generated to visualize the distribution of BV/TV throughout the joint in the metaphysis of immature specimens.

Results: The results demonstrate that variability in adult trabecular structure cannot be explained by sex or body size. During ontogeny, there is a general increase in trabecular BV/TV and Tb.Th with age, and ratios of trabecular parameters between the fore- and hindlimb may be consistent with locomotor transitions during ontogeny.

Discussion: Variation in trabecular morphology among adult individuals is not related to sex or body size, and the factors contributing to intraspecific variability, such as overall activity levels and genetic differences, require further investigation. Trabecular ontogeny in chimpanzees differs from humans in some respects, most notably the absence of a high BV/TV at birth.
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http://dx.doi.org/10.1002/ajpa.23696DOI Listing
December 2018

Dehydration of individual bovine trabeculae causes transition from ductile to quasi-brittle failure mode.

J Mech Behav Biomed Mater 2018 11 1;87:296-305. Epub 2018 Aug 1.

Institute of Lightweight Design and Structural Biomechanics, TU Wien, Getreidemarkt 9, BE02, A-1060 Vienna, Austria. Electronic address:

Trabecular bone is located inside flat bones as well as in the epi- and metaphysis of long bones and plays a key role with respect to load transfer. Disorders, such as osteoporosis, weaken the structural integrity and may also cause changes in the mechanical properties of individual trabeculae, such as Young's modulus. Knowledge of mechanical tissue properties are necessary to assess risk of bone fracture with finite element analysis (FEA). However, such parameters are most often obtained from experiments on air-dried specimens which do not reflect the physiological conditions. In this study, micro-tensile tests of individual bovine trabeculae were performed until fracture to evaluate the influence of hydration state on the elastic and post-yield behavior. Dehydration resulted in significantly (p < 0.001) lower post yield work and ultimate strain, whereas stiffness, yield stress and ultimate stress were significantly (p < 0.001) larger. Further, inelastic strain of dehydrated samples was confined to a small region, whereas it was distributed over a larger area in wet samples. Similarly, microdamage accumulation was confined to a significantly smaller region (p < 0.05) in dry samples, compared to wet ones. Thus, damage localization resulted in a quasi-brittle failure in dry samples. In contrast, hydrated samples showed a much larger area of microdamage accumulation, resulting in a ductile failure. These results emphasize the need to keep bone samples hydrated during mechanical testing. Sequentially, the findings may help to improve clinical applications like FEA-based bone strength predictions.
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http://dx.doi.org/10.1016/j.jmbbm.2018.07.039DOI Listing
November 2018

Trabecular bone patterning across the human hand.

J Hum Evol 2018 10 30;123:1-23. Epub 2018 Jul 30.

Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury CT2 7NZ, United Kingdom; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany.

Hand bone morphology is regularly used to link particular hominin species with behaviors relevant to cognitive/technological progress. Debates about the functional significance of differing hominin hand bone morphologies tend to rely on establishing phylogenetic relationships and/or inferring behavior from epigenetic variation arising from mechanical loading and adaptive bone modeling. Most research focuses on variation in cortical bone structure, but additional information about hand function may be provided through the analysis of internal trabecular structure. While primate hand bone trabecular structure is known to vary in ways that are consistent with expected joint loading differences during manipulation and locomotion, no study exists that has documented this variation across the numerous bones of the hand. We quantify the trabecular structure in 22 bones of the human hand (early/extant modern Homo sapiens) and compare structural variation between two groups associated with post-agricultural/industrial (post-Neolithic) and foraging/hunter-gatherer (forager) subsistence strategies. We (1) establish trabecular bone volume fraction (BV/TV), modulus (E), degree of anisotropy (DA), mean trabecular thickness (Tb.Th) and spacing (Tb.Sp); (2) visualize the average distribution of site-specific BV/TV for each bone; and (3) examine if the variation in trabecular structure is consistent with expected joint loading differences among the regions of the hand and between the groups. Results indicate similar distributions of trabecular bone in both groups, with those of the forager sample presenting higher BV/TV, E, and lower DA, suggesting greater and more variable loading during manipulation. We find indications of higher loading along the ulnar side of the forager sample hand, with high site-specific BV/TV distributions among the carpals that are suggestive of high loading while the wrist moves through the 'dart-thrower's' motion. These results support the use of trabecular structure to infer behavior and have direct implications for refining our understanding of human hand evolution and fossil hominin hand use.
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http://dx.doi.org/10.1016/j.jhevol.2018.05.004DOI Listing
October 2018

Trabecular bone patterning in the hominoid distal femur.

PeerJ 2018 5;6:e5156. Epub 2018 Jul 5.

Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent at Canterbury, Canterbury, Kent, UK.

Background: In addition to external bone shape and cortical bone thickness and distribution, the distribution and orientation of internal trabecular bone across individuals and species has yielded important functional information on how bone adapts in response to load. In particular, trabecular bone analysis has played a key role in studies of human and nonhuman primate locomotion and has shown that species with different locomotor repertoires display distinct trabecular architecture in various regions of the skeleton. In this study, we analyse trabecular structure throughout the distal femur of extant hominoids and test for differences due to locomotor loading regime.

Methods: Micro-computed tomography scans of ( = 11), ( = 18), ( = 14) and sp. ( = 7) were used to investigate trabecular structure throughout the distal epiphysis of the femur. We predicted that bone volume fraction (BV/TV) in the medial and lateral condyles in would be distally concentrated and more anisotropic due to a habitual extended knee posture at the point of peak ground reaction force during bipedal locomotion, whereas great apes would show more posteriorly concentrated BV/TV and greater isotropy due to a flexed knee posture and more variable hindlimb use during locomotion.

Results: Results indicate some significant differences between taxa, with the most prominent being higher BV/TV in the posterosuperior region of the condyles in and higher BV/TV and anisotropy in the posteroinferior region in . Furthermore, trabecular number, spacing and thickness differ significantly, mainly separating from the other apes.

Discussion: The trabecular architecture of the distal femur holds a functional signal linked to habitual behaviour; however, there was more similarity across taxa and greater intraspecific variability than expected. Specifically, there was a large degree of overlap in trabecular structure across the sample, and was not as distinct as predicted. Nonetheless, this study offers a comparative sample of trabecular structure in the hominoid distal femur and can contribute to future studies of locomotion in extinct taxa.
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http://dx.doi.org/10.7717/peerj.5156DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035864PMC
July 2018

Systemic patterns of trabecular bone across the human and chimpanzee skeleton.

J Anat 2018 04 18;232(4):641-656. Epub 2018 Jan 18.

Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.

Aspects of trabecular bone architecture are thought to reflect regional loading of the skeleton, and thus differ between primate taxa with different locomotor and postural modes. However, there are several systemic factors that affect bone structure that could contribute to, or be the primary factor determining, interspecific differences in bone structure. These systemic factors include differences in genetic regulation, sensitivity to loading, hormone levels, diet, and activity levels. Improved understanding of inter-/intraspecific variability, and variability across the skeleton of an individual, is required to interpret properly potential functional signals present within trabecular structure. Using a whole-region method of analysis, we investigated trabecular structure throughout the skeleton of humans and chimpanzees. Trabecular bone volume fraction (BV/TV), degree of anisotropy (DA) and trabecular thickness (Tb.Th) were quantified from high resolution micro-computed tomographic scans of the humeral and femoral head, third metacarpal and third metatarsal head, distal tibia, talus and first thoracic vertebra. We found that BV/TV is, in most anatomical sites, significantly higher in chimpanzees than in humans, suggesting a systemic difference in trabecular structure unrelated to local loading regime. Differences in BV/TV between the forelimb and hindlimb did not clearly reflect differences in locomotor loading in the study taxa. There were no clear systemic differences between the taxa in DA and, as such, this parameter might reflect function and relate to differences in joint loading. This systemic approach reveals both the pattern of variability across the skeleton and between taxa, and helps identify those features of trabecular structure that may relate to joint function.
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http://dx.doi.org/10.1111/joa.12776DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5835784PMC
April 2018

Plausibility and parameter sensitivity of micro-finite element-based joint load prediction at the proximal femur.

Biomech Model Mechanobiol 2018 Jun 30;17(3):843-852. Epub 2017 Dec 30.

Institute of Lightweight Design and Structural Biomechanics, TUW, Getreidemarkt 9/BE, Vienna, Austria.

A micro-finite element-based method to estimate the bone loading history based on bone architecture was recently presented in the literature. However, a thorough investigation of the parameter sensitivity and plausibility of this method to predict joint loads is still missing. The goals of this study were (1) to analyse the parameter sensitivity of the joint load predictions at one proximal femur and (2) to assess the plausibility of the results by comparing load predictions of ten proximal femora to in vivo hip joint forces measured with instrumented prostheses (available from www.orthoload.com ). Joint loads were predicted by optimally scaling the magnitude of four unit loads (inclined [Formula: see text] to [Formula: see text] with respect to the vertical axis) applied to micro-finite element models created from high-resolution computed tomography scans ([Formula: see text]m voxel size). Parameter sensitivity analysis was performed by varying a total of nine parameters and showed that predictions of the peak load directions (range 10[Formula: see text]-[Formula: see text]) are more robust than the predicted peak load magnitudes (range 2344.8-4689.5 N). Comparing the results of all ten femora with the in vivo loading data of ten subjects showed that peak loads are plausible both in terms of the load direction (in vivo: [Formula: see text], predicted: [Formula: see text]) and magnitude (in vivo: [Formula: see text], predicted: [Formula: see text]). Overall, this study suggests that micro-finite element-based joint load predictions are both plausible and robust in terms of the predicted peak load direction, but predicted load magnitudes should be interpreted with caution.
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http://dx.doi.org/10.1007/s10237-017-0996-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5948299PMC
June 2018

Trabecular and cortical bone structure of the talus and distal tibia in Pan and Homo.

Am J Phys Anthropol 2017 08 24;163(4):784-805. Epub 2017 May 24.

Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.

Objectives: Internal bone structure, both cortical and trabecular bone, remodels in response to loading and may provide important information regarding behavior. The foot is well suited to analysis of internal bone structure because it experiences the initial substrate reaction forces, due to its proximity to the substrate. Moreover, as humans and apes differ in loading of the foot, this region is relevant to questions concerning arboreal locomotion and bipedality in the hominoid fossil record.

Materials And Methods: We apply a whole-bone/epiphysis approach to analyze trabecular and cortical bone in the distal tibia and talus of Pan troglodytes and Homo sapiens. We quantify bone volume fraction (BV/TV), degree of anisotropy (DA), trabecular thickness (Tb.Th), bone surface to volume ratio (BS/BV), and cortical thickness and investigate the distribution of BV/TV and cortical thickness throughout the bone/epiphysis.

Results: We find that Pan has a greater BV/TV, a lower BS/BV and thicker cortices than Homo in both the talus and distal tibia. The trabecular structure of the talus is more divergent than the tibia, having thicker, less uniformly aligned trabeculae in Pan compared to Homo. Differences in dorsiflexion at the talocrural joint and in degree of mobility at the talonavicular joint are reflected in the distribution of cortical and trabecular bone.

Discussion: Overall, quantified trabecular parameters represent overall differences in bone strength between the two species, however, DA may be directly related to joint loading. Cortical and trabecular bone distributions correlate with habitual joint positions adopted by each species, and thus have potential for interpreting joint position in fossil hominoids.
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http://dx.doi.org/10.1002/ajpa.23249DOI Listing
August 2017