Home / Univ.-Prof. DI Dr. Dieter Pahr

Univ.-Prof. DI Dr. Dieter Pahr

Dept. Anatomy and Biomechanics, Division Biomechanics (Head)

Publications

  1. 2018

    • Journal Article

      • Georgiou, L., Kivell T. L., Pahr D. H., & Skinner M. M.
        (2018).  Trabecular bone patterning in the hominoid distal femur.
        PeerJ. 6, e5156.

      • Lu, S. C., Vereecke E. E., Synek A., Pahr D. H., & Kivell T. L.
        (2018).  A novel experimental design for the measurement of metacarpal bone loading and deformation and fingertip force.
        PeerJ. 6, e5480.

      • Panyasantisuk, J., Dall'Ara E., Pretterklieber M., Pahr D. H., & Zysset P. K.
        (2018).  Mapping anisotropy improves QCT-based finite element estimation of hip strength in pooled stance and side-fall load configurations.
        Medical Engineering & Physics. 59, 36-42.

      • Synek, A., Dunmore C. J., Kivell T. L., Skinner M. M., & Pahr D. H.
        (2018).  Inverse remodelling algorithm identifies habitual manual activities of primates based on metacarpal bone architecture.
        Biomechanics and Modeling in Mechanobiology.

  2. 2017

    • Journal Article

      • Benca, E., Reisinger A., Patsch J. M., Hirtler L., Synek A., Stenicka S., et al.
        (2017).  Effect of simulated metastatic lesions on the biomechanical behavior of the proximal femur.
        Journal of Orthopaedic Research. 35, 2407-2414.

Research Projects

  • FAM-3D

    Functional anatomical 3D-models

    • Project Number: FTI18
    • Project Lead: Nikolaus Dellantoni, ACMIT - Austrian Center for Medical Innovation and Technology
    • Project Partner: Karl Landsteiner University of Health Sciences / Department Anatomy and Biomechanics, NÖ Landeskliniken Holding / X-ray Institute for Diagnostics, Interventional Radiology and Nuclear Medicine
    • Duration: 36 months starting from 01.04.2019
  • Reproducing biological tissues

    Reproducing biological tissues in terms of their mechanical properties by means of 3D printing

    • Project Number: SC17_016
    • Project Lead: Dieter Pahr, Karl Landsteiner University of Health Sciences / Division Biomechanics
    • Duration: 36 months starting from 01.12.2018

    Background

    3D printing, also known as additive manufacturing (AM) or rapid prototyping, has become a highly versatile tool with a broad range of applications, such as manufacturing, art, design, and medicine. In the field of biomedical engineering AM has not only gained wide popularity in tissue engineering for printing scaffolds and in biomechanics for patient-specific prostheses, but it has also been proposed as an instrument for fabricating realistic 3D models. For example, individual modelling of patient-specific conditions via AM poses an excellent opportunity for surgeons to practice procedures beforehand. Studies have shown that in doing so operation time is reduced and the physician's confidence is increased, resulting in shorter times of radiation exposure and lower costs. Although 3D modelling approaches for pre-surgical planning have been reported previously, a closer look, concerning the mechanical properties of the printed materials, is still required. Currently, these models lack accurate representation of the tissue biomechanics. This demands a procedure for fine-tuning the mechanical properties of the 3D printed materials to closely match the in vivo conditions. In this project, 3D printing is applied to the task of producing materials that closely imitate biological tissues, and organ-like structures, in terms of their mechanical properties. The printed tissues can be patient-specific for pre-surgical planning, as well as standardized for applications in research dealing with advancing novel operating techniques, implant technology, and other medical devices. One of the incentives is to thereby limit the demand of donor organs and reduce variability of the organs used in research. Due to the fact that the capabilities of 3D printing are currently rapidly increasing, this research can also be seen as the groundwork for even more applications concerning printed organs that might be possible with future technology. The key objectives of this project are:
    the establishment of a testing protocol for acquiring characteristic biomechanical parameters of different tissues, the development of software tools for attaining these parameters in 3D printed structures (based on suitable material combinations and spatial distribution thereof, plus post-processing procedures), the printing of these tissue replicas alongside the validation of their mechanical properties via comparison with the actual tissue characteristics. All instructions for manufacturing these models are to be contained in a so-called “toolbox”.

  • Digitisation as a chance for restoration and visualisation

    Digitisation as a chance for restoration and visualisation – A pilot study on the 30,000 year old double burial of newborns from Krems-Wachtberg

    • Project Number: FTI17-010
    • Project Lead: Dieter Pahr, Karl Landsteiner University of Health Sciences / Division Biomechanics
    • Project Partner: Museum of Natural History Vienna / Department of Anthropology, Danube University Krems / Collection Studies and Management, Austrian Academy of Science / Institute for Oriental and European Archaeology
    • Duration: 24 months starting from 01.11.2018

    Background

    The discovery of the more than 30,000 years old ritual double burial of two neonates at the Krems-Wachtberg site in 2005 has evoked much attention not only by the media and the general public, but also from the international scientific community as findings of sub adults of ancient humans are, on a global scale, extremely rare occasions. After the discovery and exposure the ritual burial was carefully recovered as a block, and the fragile specimens were stored to keep its original excellent condition. In 2015 the recovered block was excavated, documenting each single step with state-of-the art methods.
    Digitisation is now aimed for to enable analyses, restoration and also visualisation. Currently, the only non-destructive way to make a digital copy and visualize the remains is high-resolution micro-computed tomography imaging. It allows 3D reconstruction of the surface as well as the inner micro-structure - making it possible to “uncover the invisible”. Such a device has been installed at the division for Biomechanics of KL University as part of the Core Facility at Campus Krems. This will overcome the current restrictions of analysis and allows a digitisation of the findings for future analysis.
    Together with the available light scanning data from the excavation the whole assembly can be reconstructed. Apart from 3-dimensional reconstruction it will be possible to restorate the chaîne operatoire of activities which were part of this burial process, as well as the post-sedimentary formation processes (4D = modelling the development through time).
    In addition to the reconstruction of the burial, up-to-date documentation and archiving of the data is of utmost importance to lay a basis for further research. Thus, one of the main objectives of this pilot project is to set up a catalogue of criteria for a long term, open-source data repository which provides access to all the data regarding the excavation and findings for larger groups of scientists beyond disciplinary borders.
    Digitisation of the Krems-Wachtberg double burial is challenging in all respects and requires a variety of experts to deal with the many aspects that are inherent in such a spectacular discovery. For the first time, it is possible to investigate this outstanding find from Krems-Wachtberg under the leadership of Lower Austrian research institutions. As one of its main targets, the proposed project will contribute to a further professionalization in Collection Management and Museology – one of the areas of Lower Austrian FTI strategy – and it will significantly improve the visibility of cultural heritage in Lower Austria by latest technical developments that allow for scientific exploitation on an international level.

  • HIPStar

    Obesity-specific joint center estimation in gait analysis

    • Project Number: P 30923-B30
    • Project Lead: Brian Horsak, FH St. Pölten / Institute of Health Sciences
    • Project Partner: Karl Landsteiner University of Health Sciences / Division Biomechanics, Medical University of Vienna / Department of Pediatrics and Adolescent Medicine, Orthopaedic Hospital Vienna-Speising
    • Duration: 36 months starting from 01.10.2018

    Background

    Gait analysis aims at gathering quantitative information about the mechanics of the musculo-skeletal system during locomotion. Typically, in gait analysis, variables such as kinematics, joint moments, and powers are determined. This information is used to evaluate pathological gait patterns. Errors in locating the three-dimensional (3D) position of the hip joint center (HJC) can strongly affect the calculation of 3D gait analysis variables. This consequentially leads to incorrect interpretations. The problem of inaccuracy in HJC location increases significantly in patients where bony landmarks are difficult to identify, such as in overweight or obese populations. Nevertheless, gait analysis remains as the state of the art method for clinicians and for researchers. Often medical imaging-based methods are recommended to identify the 3D HJC localization. However, some of those methods expose patients to radiation or are expensive and time-consuming. Therefore, non-invasive predictive methods, based on experimental data, or functional models were introduced in recent years to estimate the position of the HJC. Researcher has attempted to evaluate which of these methods best determine the HJC most accurately in various populations. Among those, only a few studies recruited children or clinically diagnosed patients. Surprisingly, there is no study, which recruited overweight or obese children and adolescents. However, all currently non-invasive available methods are strongly affected by the amount of subcutaneous fat present (wobbling mass), which can introduce great inaccuracies. Therefore, a study to identify how well existing HJC estimation methods work for this very specific population is strongly recommended. In addition, new methods such as 3D free-hand ultrasound techniques (3DUS) may bear great potential for accurate and non-invasive estimation techniques. These methods, are still experimental and have not yet been tested in overweight populations.
    The primary aim of this study is to evaluate the accuracy of current non-invasive HJC estimation methods for clinical 3D gait analysis to magnetic resonance imaging (MRI) in a population of overweight or obese children and adolescents. Based on the results obtained in this study, we will (i) provide recommendations, for which methods serve best to estimate the HJC position; (ii) develop soft tissue compensation algorithms and strategies that allow for a more accurate estimation of the HJC; (iii) in addition, we will evaluate the use of 3DUS as a promising alternative in HJC estimation.

  • BEST MgAlloy

    Biocompatible elements - simulations and tests for Mg alloys

    • Project Number: KF3-F-639/004-2017
    • Project Partner: Aerospace & Advanced Composites GmbH, FH Wiener Neustadt, AC2T research GmbH, Karl Landsteiner University of Health Sciences / Division Biomechanics
    • Duration: 36 months starting from 01.04.2018

    Background

    Biodegradable magnesium-based implants are increasingly coming into focus for temporary use in medical applications, such as plates, nails, pins or screws for osteosynthesis of broken bones. The great advantage of this is the elimination of a second operation for explanting any permanent metallic fixations.

  • Endobone

    Developmental tissue engineering model of endochondral ossification for bone regeneration

    • Project Number: LSC16_024
    • Project Lead: Stefan Nehrer, Danube University Krems / Department of Regenerative Medicine
    • Project Partner: Karl Landsteiner University of Health Sciences / Division Biomechanics
    • Duration: 36 months starting from 01.01.2018

    Background

    Bone engraftment techniques to treat large bone defects involve implantation of allogenic bone grafts as a replacement tissue but are constrained on poor integration and functional anastomosis for ingrowth of vasculature from the host tissue. In proportionate many unresolved factors are to be addressed in advancing the clinical outcome for treating fracture non-unions, osteonecrosis, osteoporosis. Tissue engineering strategies hold promise in promoting bone regeneration. Nevertheless, the common approach in bone tissue engineering is by stimulating the osteogenesis route for regenerating bone which still remains an ineffective approach. Mimicking the natural process of bone formation through a developmental mechanism for formation of long bones called endochondral ossification has been envisioned from the commencement of research in the field of bone tissue engineering. In the current proposal, we propose a strategy for bone regeneration with naturally derived biomaterials incorporating extracellular matrix derived from cartilage (CD-ECM) as a template. We hypothesize that bone regeneration through a cartilaginous intermediate template onto solid biomaterials will produce a neotissue that mimics the native bone in its structure and functionality. To test this hypothesis we will compare bone regeneration from the proposed model to the gold-standard bone allografts used in clinics. CD-ECM incorporated biomaterials embedding hypertrophic chondrocytes are evaluated for their mineralized matrix formation in vitro with biochemical analysis and histological evaluation. Further, by non-destructive analysis micro-computed tomography (µCT) monitoring generated 3D segmented images and biomechanical testing of the scaffolds are evaluated together with computational finite element modelling simulations to determine the stiffness, strength of the engineered bone. The CD-ECM incorporated biomaterials are then implanted with or without hypertrophic chondrocytes ectopically in a mouse model for de novo mineralized matrix formation. The bone formation is further assessed by biochemical, µCT, biomechanical, computational modelling. This interdisciplinary approach would aid in a developmental engineering process instructing bioresponsive scaffolds to recapitulate native bone repair mechanisms.

  • Medi3D Print

    3D print of biological materials

    • Project Lead: Nikolaus Dellantoni, ACMIT - Austrian Center for Medical Innovation and Technology
    • Project Partner: Karl Landsteiner University of Health Sciences / Division Biomechanics
    • Duration: 36 months starting from 01.01.2018

    Background

    3D printing is entering medicine and can help in many ways. In addition to accurately fitting implants and orthoses, 3D printing can be used in surgical preparation to gain a better understanding of the planned surgery. Increasingly, the printing of organs is becoming more important. In this research project materials are to be printed with the help of the Polyjet process which come as close as possible to real biological tissues from the haptic but also with regard to the biomechanical behavior. The printing technology developed in this way enables the production of patient-specific organ models based on CT and MRI data, which can be used for preoperative planning prior to complicated procedures. Furthermore, for the further development of surgical techniques and implants mechanically equivalent organs or specimens can be produced, which make dispensing with the use of body donations for these concerns. The printed organs are standardizable and have no undesirable variability, as is the case with body donation.

  • Novel biomechanical test setup

    Development of a novel biomechanical test setup together with bone strength simulation models to improve the diagnoses and treatment of osteoporosis

    • Project Number: SC16_009
    • Project Lead: Dieter Pahr, Karl Landsteiner University of Health Sciences / Division Biomechanics
    • Duration: 36 months starting from 01.09.2017

    Background

    Osteoporosis (OP) is a silent bone disease resulting in loss of bone density, decreased bone strength and ultimately fracture. It is underrated, underdiagnosed and undertreated. Every third women and every fifth men over 50 are concerned. OP is responsible for more than 4 million fractures annually in the EU, with hip fracture as the most common type. This translates into more than €40 billions of health care costs, out of which less than 5% is spent on prevention. Beside diabetes, cardiovascular diseases, and cancer it’s one of the important health care challenges in the next decades. Especially in Lower Austria this puts an estimated €200 million of annual burden on the healthcare system only. The early diagnostics of OP is vital for fracture prevention. This in return increases the life quality of the patient, and decreases the healthcare and social costs. Bone density is used as predictor of osteoporotic fracture risk. It is measured with DEXA and diagnosed with a derived T-score. However, recent studies showed the inaccuracy and insufficiency of such densitometry measures. For example, more than 50% of OP fractures occur in the patients who are considered as “low risk” by this method, and 15% of patients are falsely treated for being at "high risk". An improvement of this situation needs (a) better screening techniques, (b) more screening, and (c) improved diagnosis scores. The goal of this project is to improve osteoporosis diagnostic tools. Bone fracture happens because of overloading and/or reduced resistance against loading due to bone loss. Finite element analysis (FEA) simulation is a non-invasive numerical method which is able to estimate individual bone strength in-vivo based on DEXA or Quantitative Computed Tomography (QCT) images. Geometrical, structural, and material properties are computed from images and combined with typical physiological loading conditions including the magnitude, direction, and frequency of the loading. The accuracy of the model is inherited from a good knowledge of all these parameters. FEA -based bone strength has the potential to effectively improve diagnosis, assessment, and monitoring of osteoporosis. But despite the significant progress made in the last decade, these predictions still need considerable improvements through enhancements in imaging, mechanical testing, and simulation techniques to justify their clinical use.

  • M3dRES

    Additive Manufacturing for Medical Research

    • Project Number: FFG858060
    • Project Lead: Francesco Moscato, Medical University of Vienna / Center for Medical Physics and Biomedical Engineering
    • Project Partner: ACMIT - Austrian Center for Medical Innovation and Technology, Karl Landsteiner University of Health Sciences / Division Biomechanics
    • Duration: 36 months starting from 01.05.2017

    Background

    The M3dRES project aims at establishing a unique infrastructure devoted to 3d-printing for medical research in a strongly interdisciplinary environment.
    M3dRES provides essential tools for the personalized patient treatment, for the enhancement of medical imaging, for the acceleration of tissue engineering and regenerative medicine, and for the modernization of current medical education.

  • OsteoSim

    Computer simulation models for the early detection of osteoporosis

    • Project Number: FFG850746
    • Project Lead: Dieter Pahr, Karl Landsteiner University of Health Sciences / Division Biomechanics
    • Project Partner: Danube University Krems / Department of Regenerative Medicine, Braincon GmbH&CoKG, Technische Universität Wien / Institute for Lightweight Design and Structural Biomechanics
    • Duration: 36 months starting from 01.12.2015

    Background

    Osteoporosis is a common age disease of the bone. The cause of osteoporosis is usually a hormonal change. Older women are predominantly affected, but men are also increasingly suffering from this disease. The widespread of osteoporosis is gradually becoming a health economic problem. Osteoporosis gradually reduces bone density. As a result, the entire skeleton is weakened biomechanically and it is more likely to suffer from bone fractures. In clinical practice, the diagnosis of osteoporosis or, in general, the estimation of a fracture risk on the basis of bone density measurement (BMD measurement) is carried out. According to WHO, a T <-2.5 standard deviation is the critical threshold for the diagnosis of osteoporosis. Unfortunately, results of studies (eg, Rotterdam study3) show that in a group with non-vertebral fractures, only 44 percent of women and 21 percent of men had a value below -2.5. The final goal is to combine both medical reports from osteoporosis and osteoarthrosis together with new, validated assessment models, which gives better results than the T-score. As a secondary goal, relationships and possible interactions of both diseases are shown. This is to be achieved by four research tasks: new models of osteoporosis, standardization of radiographs, combined findings - correlations osteoporosis and osteoarthrosis, validation of new osteoporosis assessment models.

Events

  1. 27 May

    ÖH Elections at KL University

    27. May 2019, 11:30 - 29. May 2019, 10:30
    Karl Landsteiner Privatuniversität, Trakt X / Besprechungsraum EG
  2. 15 Jun

    5. Campus-Ball Krems

    15. June 2019, 19:00 - 16. June 2019, 04:00
    Campus Krems, Dr.-Karl-Dorrek-Straße 30
  3. 07 Jul

    ESBiomech Conference 2019

    07. July 2019, 08:30 - 10. July 2019, 18:00
    University of Vienna