@article{SchmidtPenzkoferBachmaieretal., author = {Schmidt, Ulf and Penzkofer, Rainer and Bachmaier, Samuel and Augat, Peter}, title = {Implant Material and Design Alter Construct Stiffness in Distal Femur Locking Plate Fixation: A Pilot Study}, series = {Clinical Orthopaedics and Related Research®}, volume = {471}, journal = {Clinical Orthopaedics and Related Research®}, number = {9}, publisher = {The Association of Bone and Joint Surgeons}, doi = {10.1007/s11999-013-2867-0}, pages = {2808 -- 2814}, abstract = {BACKGROUND: Construct stiffness affects healing of bones fixed with locking plates. However, variable construct stiffness reported in the literature may be attributable to differing test configurations and direct comparisons may clarify these differences. QUESTIONS/PURPOSES: We therefore asked whether different distal femur locking plate systems and constructs will lead to different (1) axial and rotational stiffness and (2) fatigue under cyclic loading. METHODS: We investigated four plate systems for distal femur fixation (AxSOS, LCP, PERI-LOC, POLYAX) of differing designs and materials using bone substitutes in a distal femur fracture model (OTA/AO 33-A3). We created six constructs of each of the four plating systems. Stiffness under static and cyclic loading and fatigue under cyclic loading were measured. RESULTS: Mean construct stiffness under axial loading was highest for AxSOS (100.8 N/mm) followed by PERI-LOC (80.8 N/mm) and LCP (62.6 N/mm). POLYAX construct stiffness testing showed the lowest stiffness (51.7 N/mm) with 50\% stiffness of AxSOS construct testing. Mean construct stiffness under torsional loading was similar in the group of AxSOS and PERI-LOC (3.40 Nm/degree versus 3.15 Nm/degree) and in the group of LCP and POLYAX (2.63 Nm/degree versus 2.56 Nm/degree). The fourth load level of > 75,000 cycles was reached by three of six AxSOS, three of six POLYAX, and two of six PERI-LOC constructs. All others including all LCP constructs failed earlier. CONCLUSIONS: Implant design and material of new-generation distal femur locking plate systems leads to a wide range of differences in construct stiffness. CLINICAL RELEVANCE: Assuming construct stiffness affects fracture healing, these data may influence surgical decision-making in choosing an implant system.}, language = {en} } @article{HeineEigenbergerBrebantetal., author = {Heine, Norbert and Eigenberger, Andreas and Brebant, Vanessa and Kempa, Sally and Seitz, Stephan and Prantl, Lukas and Kuehlmann, Britta}, title = {The effect of radiotherapy on fat engraftment for complete breast reconstruction using lipofilling only}, series = {Archives of Gynecology and Obstetrics}, journal = {Archives of Gynecology and Obstetrics}, publisher = {Springer}, doi = {10.1007/s00404-022-06610-4}, pages = {7}, abstract = {Purpose Lipofilling has been established as a standard technique for contour enhancement following breast reconstruction. However, there is a paucity in current literature regarding the use of this technique for complete reconstruction of the female breast as an alternative to conventional techniques, such as expander or flap-based procedures. In particular, the influence of pre-operative irradiation for successful reconstruction has rarely been examined in published studies. Here, the authors describe their experience with successful fat injection in pre-radiated breasts in comparison with non-pre-radiated patients. Methods In this retrospective study, we examined a total of 95 lipofilling treatments on 26 patients (28 breasts). All of them experienced mastectomy following breast cancer; local breast defects after partial resection of the gland were not included in this study. In total, 47 lipofilling procedures in 12 non-irradiated patients (14 breasts) and 48 procedures in 14 irradiated women (also 14 breasts) were performed. Per session, approximately 297 +/- 112 cc of adipose tissue was grafted in group A (no radiotherapy) and approximately 259 +/- 93 cc was grafted in group B (radiotherapy). Results Among the group of women without pre-operative radiation, 71\% of breast reconstructions limited to lipofilling only showed constant engraftment of fat tissue with a successful reconstructive result, whereas only 21\% of the patients with pre-radiated breasts showed complete reconstruction of the breast with a permanent fat in-growth. Conclusion Preoperative radiotherapy significantly impedes successful completion of breast reconstructions planned only by autologous fat transfer. Patients should be selected individually and carefully for complete breast reconstruction using lipofilling only.}, language = {en} } @inproceedings{SchaefferHerrmannBoehm, author = {Schaeffer, Leon and Herrmann, David and B{\"o}hm, Valter}, title = {Concept of a wrist Hand Orthosis based on a prestressed compliant structure}, series = {Proceedings of the 7th International Conference on Biomedical Engineering and Applications (ICBEA), Hangzhou, China, 21-23 April 2023}, booktitle = {Proceedings of the 7th International Conference on Biomedical Engineering and Applications (ICBEA), Hangzhou, China, 21-23 April 2023}, publisher = {IEEE}, doi = {10.1109/ICBEA58866.2023.00024}, pages = {98 -- 103}, abstract = {In the treatment of hand injuries in the context of orthopedic care, movable wrist hand orthoses are used in numerous instances. Early motion therapy is in most cases advantageous for adequate, rapid and successful long-term healing of the hand. Conventional dynamic wrist hand orthoses can only be used for movement therapy to a limited extent since they represent the wrist as a simple rotating joint and neglect the complexity of the hand movement possibilities. In this paper, a preliminary concept for dynamic wrist hand orthoses based on prestressed compliant structures is presented. The distinctive feature of this concept lies in the enabling of multiaxial motion capabilities of the human hand without applying conventional joints. According to the concept the wrist region is surrounded by a prestressed compliant structure. Besides the derivation and description of the concept, a first three-dimensional computer-aided design is shown. Additionally, the necessary steps in the development of such a novel dynamic wrist orthosis are discussed.}, language = {en} } @article{HimmeleinPerezRuizdeGaribayBrandeletal., author = {Himmelein, Susanne and Perez Ruiz de Garibay, Aritz and Brandel, Veronika and Zierfuß, Frank and Bingold, Tobias Michael}, title = {The ADVanced Organ Support (ADVOS) hemodialysis system removes IL-6: an in vitro proof-of-concept study}, series = {Intensive care medicine experimental}, volume = {12}, journal = {Intensive care medicine experimental}, number = {1}, publisher = {SpringerOpen}, address = {Berlin ; Heidelberg}, issn = {2197-425X}, doi = {10.1186/s40635-024-00652-5}, abstract = {BACKGROUND IL-6 is a pleiotropic cytokine modulating inflammation and metabolic pathways. Its proinflammatory effect plays a significant role in organ failure pathogenesis, commonly elevated in systemic inflammatory conditions. Extracorporeal blood purification devices, such as the Advanced Organ Support (ADVOS) multi hemodialysis system, might offer potential in mitigating IL-6's detrimental effects, yet its efficacy remains unreported. METHODS We conducted a proof-of-concept in vitro study to assess the ADVOS multi system's efficacy in eliminating IL-6. Varying concentrations of IL-6 were introduced into a swine blood model and treated with ADVOS multi for up to 12 h, employing different blood and concentrate flow rates. IL-6 reduction rate, clearance, and dynamics in blood and dialysate were analyzed. RESULTS IL-6 clearance rates of 0.70 L/h and 0.42 L/h were observed in 4 and 12-h experiments, respectively. No significant differences were noted across different initial concentrations. Reduction rates ranged between 40 and 46\% within the first 4 h, increasing up to 72\% over 12 h, with minimal impact from flow rate variations. Our findings suggest that an IL-6-albumin interaction and convective filtration are implicated in in vitro IL-6 elimination with ADVOS multi. CONCLUSIONS This study demonstrates for the first time an efficient and continuous in vitro removal of IL-6 by ADVOS multi at low blood flow rates. Initial concentration-dependent removal transitions to more consistent elimination over time. Further clinical investigations are imperative for comprehensive data acquisition.}, language = {en} } @article{UhrhanSchwindtWitte, author = {Uhrhan, Katja and Schwindt, Esther and Witte, Hartmut}, title = {Fabrication and Dielectric Validation of an Arm Phantom for Electromyostimulation}, series = {Bioengineering}, volume = {11}, journal = {Bioengineering}, number = {7}, publisher = {MDPI}, address = {Basel}, issn = {2306-5354}, doi = {10.3390/bioengineering11070724}, abstract = {Electromyostimulation (EMS) is an up-and-coming training method that demands further fundamental research regarding its safety and efficacy. To investigate the influence of different stimulation parameters, electrode positions and electrode sizes on the resulting voltage in the tissue, a tissue mimicking phantom is needed. Therefore, this study describes the fabrication of a hydrogel arm phantom for EMS applications with the tissue layers of skin, fat, blood and muscle. The phantom was dielectrically validated in the frequency range of 20 Hz to 100 Hz. We also conducted electromyography (EMG) recordings during EMS on the phantom and compared them with the same measurements on a human arm. The phantom reproduces the dielectric properties of the tissues with deviations ranging from 0.8\% to more than 100\%. Although we found it difficult to find a compromise between mimicking the permittivity and electrical conductivity at the same time, the EMS-EMG measurements showed similar waveforms (1.9-9.5\% deviation) in the phantom and human. Our research contributes to the field of dielectric tissue phantoms, as it proposes a multilayer arm phantom for EMS applications. Consequently, the phantom can be used for initial EMS investigations, but future research should focus on further improving the dielectric properties.}, language = {en} } @article{BartschBehamGebhardtetal., author = {Bartsch, Alexander and Beham, Daniela and Gebhardt, Jakob and Ehrlich, Ingo and Schratzenstaller, Thomas and Monkman, Gareth J.}, title = {Mechanical Properties of NdPrFeB Based Magnetoactive Bisphenol-Free Boron-Silicate Polymers}, series = {Journal of Nanomedicine and Nanotechnology}, volume = {14}, journal = {Journal of Nanomedicine and Nanotechnology}, number = {6}, publisher = {Walsh Medical Media}, issn = {2157-7439}, doi = {10.35248/2157-7439.23.14.705}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-67425}, abstract = {Following a ban on many materials containing bisphenol-A, new bisphenol-free Boron silicates have been found as substitutes. The purpose of this study is to describe the mechanical properties of these bisphenol-free magnetoactive borosilicate polymers containing hard magnetic particles. Samples of 0\%, 33\% and 66\% by wt. were loaded for compression using a universal testing machine. The maximum forces occurring for different travel speeds were compared before and after post-magnetization treatments. The post-magnetization included 2 stages. In addition, the change in mechanical properties within 24 hours after the post-magnetization process was investigated. Furthermore, the influence of speed and particle content were investigated. In general, there is a correlation between the required compressive force and, the level of post-magnetization stress, the increase in travel speed and particle content in the boron silicate. Comparison of the non-post-magnetized and post-magnetized samples using two-tailed t-tests shows that the p-values for all weight fraction changes in NdPrFeB particles and travel speeds are less than 0.001. Also, a comparison between tests in which the traverse speed was varied also showed significant changes in the resulting compression forces. The same is valid for changes in the weight ratio of the NdPrFeB particles in the samples. For post-magnetized samples, no significant difference can be observed in the first 24 hours following magnetization. In summary, the material presents viscoelastic, plastic force-displacement behavior, which can be well recognized by its bi-linear curve shape. The investigation shows that borosilicate polymers based on NdPrFeB can have their mechanical behavior modified and controlled by post-magnetization processes. This opens new possibilities for many future applications.}, language = {en} } @inproceedings{SchaefferHerrmannBoehm, author = {Schaeffer, Leon and Herrmann, David and B{\"o}hm, Valter}, title = {Preliminary theoretical considerations of a hand orthosis based on a prestressed, compliant structure}, series = {Proceedings of the 2023 International Symposium on Medical Robotics (ISMR), Atlanta, 19-21 April 2023}, booktitle = {Proceedings of the 2023 International Symposium on Medical Robotics (ISMR), Atlanta, 19-21 April 2023}, publisher = {IEEE}, doi = {10.1109/ISMR57123.2023.10130230}, pages = {1 -- 7}, abstract = {In the treatment of hand injuries in the context of orthopedic care, movable hand orthoses are used in many cases. Early motion therapy is in most cases advantageous for adequate, rapid, and successful long-term healing of the hand. Conventional mobile hand orthoses can only be used for movement therapy to a limited extent since they represent the wrist as a simple rotating joint and neglect the complexity of the movement possibilities of the hand. In this paper, a novel concept for movable hand orthoses based on prestressed compliant structures is presented. The advantage with this concept is that it replicates the multiaxial motion capabilities without the need for conventional joints. Besides the derivation and description of the concept, a first three-dimensional CAD design is shown. Additionally, the next planned steps in the development of such a novel dynamic hand orthosis are described.}, language = {en} } @inproceedings{SchaefferHerrmannBoehm, author = {Schaeffer, Leon and Herrmann, David and B{\"o}hm, Valter}, title = {Theoretical considerations on a 2D compliant tensegrity joint in context of a biomedical application}, series = {Engineering for a changing world : 60th ISC, Ilmenau Scientific Colloquium, Technische Universit{\"a}t Ilmenau, September 4-8, 2023}, booktitle = {Engineering for a changing world : 60th ISC, Ilmenau Scientific Colloquium, Technische Universit{\"a}t Ilmenau, September 4-8, 2023}, publisher = {Technische Universit{\"a}t Ilmenau}, address = {Ilmenau}, doi = {10.22032/dbt.58879}, pages = {1 -- 15}, abstract = {In this paper, a two-dimensional compliant tensegrity joint was investigated for potential biomedical applications such as orthotics or exoskeletons. The structure consists of two compressed members connected by five compliant tensioned members. The concept is based on the tensegrity principle, which allows the realization of dynamic orthoses without conventional hinge joints. Another advantage is the adaptability to the individual needs of the patient through a suitable design of the structure and the careful selection of the characteristics of the elements. Using geometric nonlinear analysis, the mechanical behavior of the structure was investigated, focusing on mechanical compliance. The main objective was to determine the influence of the initial length and stiffness of the tensioned members and the influence of the magnitude of external forces on the overall stiffness of the movable member of the structure. The results highlight the significant impact of member parameters on the structure's stiffness and movability under varying load magnitudes. The research laid the foundation for future development of dynamic orthoses based on this structure.}, language = {en} } @misc{Dendorfer, author = {Dendorfer, Sebastian}, title = {Sturz- und Frakturpr{\"a}vention: Use it or lose it!}, series = {10 Jahre Alterstraumatologie Caritas Krankenhaus St. Josef Regensburg}, journal = {10 Jahre Alterstraumatologie Caritas Krankenhaus St. Josef Regensburg}, language = {de} } @inproceedings{Fuhrmann, author = {Fuhrmann, Thomas}, title = {Semi-Structured Lab Projects in Communication Engineering Education}, series = {2023 IEEE Global Engineering Education Conference (EDUCON), 01-04 May 2023, Kuwait}, booktitle = {2023 IEEE Global Engineering Education Conference (EDUCON), 01-04 May 2023, Kuwait}, publisher = {IEEE}, doi = {10.1109/EDUCON54358.2023.10125244}, pages = {1 -- 5}, abstract = {It is generally known that project-based learning is a very important part of engineering education to connect theoretical knowledge with practical work. Students learn to apply their knowledge to real-world challenges as it is the case in their later professional life. If students are not used to project work or the scientific topic is new and relatively complex, they may be overwhelmed. The consequence is that students achieve poor results, are frustrated, and therefore learning success is low. Semi-structured projects are introduced that combine the advantages of structured experiments with projects. The project work is structured into several parts with detailed descriptions of the tasks. In the end, students get similar results to doing a free project, but the success rate is higher due to higher guidance. Therefore, these semi-structured projects are seen to be an appropriate method to guide students to learn how to do project work. The feedback from most students is very positive. Some students with no previous lab experience complained about the project work and wished for more guidance to become familiar with lab work. In sum, the student feedback is encouraging to develop semi-structured projects further.}, language = {en} }