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This study aims to assess whether ultra-high-molecular-weight polyethylene (UHMWPE) fibers can be successfully embedded in a polylactic acid (PLA) matrix in a material extrusion 3D printing (ME3DP) process, despite the apparent thermal incompatibility between the two materials. The work started with assessing the maximum PLA extrusion temperatures at which UHMWPE fibers withstand the 3D printing process without melting or severe degradation. After testing various fiber orientations and extrusion temperatures, it has been found that the maximum extrusion temperature depends on fiber orientation relative to extrusion pathing and varies between 175 &deg, C and 185 &deg, C at an ambient temperature of 25 &deg, C. Multiple specimens with embedded strands of UHMWPE fibers have been 3D printed and following tensile strength tests on the fabricated specimens, it has been found that adding even a small number of fiber strands laid in the same direction as the load increased tensile strength by 12% to 23% depending on the raster angle, even when taking into account the decrease in tensile strength due to reduced performance of the PLA substrate caused by lower extrusion temperatures.

The growing field of translational myology continually seeks to define and promote the generalizability of muscle research to clinical practice via optimizing the transition of a wide variety of investigative muscle assessment modalities. There are distinct challenges in all facets of this research, but understanding the physiological importance of mobility currently presents a strategic priority. The severe physiological consequences from the loss of mobility are experienced by all of us: whether induced by normative ambulatory challenges as we age or as sequela of lower extremity pathology. Indeed, a growing wealth of literature clearly implicates mobility loss with a plethora of comorbidities, leading to an increasingly deleterious quality of life and ultimately resulting in early mortality. The loss of mobility is concomitantly evidenced by the progressive decline of skeletal muscle size and quality – phenomena which altogether define muscle degeneration. Nonetheless, complete etiological definitions and methodological comparisons for the precise, non-invasive quantification of muscle degeneration remains disparately described in literature. This thesis focuses on the development, application, and assessment of novel methods in computational and mathematical modeling of medical images to quantify muscle degeneration and optimize our understanding of two mobility-restorative procedures: Functional Electrical Stimulation and Total Hip Arthroplasty. Additional impacts of these methods are further explored in defining multimodal metrics for mobility analysis, characterizing the utility of 3D printing for surgical planning, modeling craniofacial electromyography, and computing pre-surgical periprosthetic fracture risk. Results from these investigations altogether present the efficacies and limitations of available image processing modalities, and introduce novel methodologies, such as nonlinear trimodal regression analysis of radiodensitometric distributions and computational interference fitting for periprosthetic femoral fracture analysis. Such analyses and perspectives are herein presented in both a theoretical and practical context. Standardizing computational modeling methodologies for medical image assessment in these contexts would allow for the generalizability of such research to the indication of respective compensatory targets for clinical intervention., Vöðvafræði er vaxandi svið sem sækist að því að skilgreina og upphefja rannsóknir á vöðvakerfinu svo hægt sè að nýta þekkinguna í klínísku umhverfi. Þessu er náð fram með því að nýta þær rannsóknaraðferðir við höfum nú þegar, til hins ýtrasta. Það eru fjölbreytilegar áskoranir og erfiðleikar framundan en það má ekki aftra okkur. Mikilvægi þess að skilja þörf líkamans fyrir hreyfingu er mikið forgangsatriði. Við höfum öll orðið vitni að því hvað gerist við fólk þegar hreyfigetan hverfur, hvort sem það er ellin sem kippir undan okkur eða afleiðingar sjúkdóma, þá benda rannsóknir til þess að takmarkanir á hreyfigetu dragi verulega úr lífsgæðum fólks og stuðlað að hærri dánartíðni. Minnkuð hreyfigeta er bókfærð með mælingum á stærð og gæðum beinagrindarvöðva - Hlutir sem skilgreina vöðvarýrnun. Engu að síður eru læknisfræðilegar skilgreiningar og óáreitandi aðferðum við öflun gagna ekki einhvað sem er vanalega lýst í greinargerðum. Þessi ritgerð einblínir á þróun, nýtingu og mat á nýjum aðferðum sem hægt er að nota við öflun gagna og nýtingu þeirra við þær tvær aðferðir sem við höfum til að hjálpa fólki með minnkaða hreyfigetu: rafstuðsmeðferð og gerfiliðaraðgerð á mjöðm. Áframhaldandi afleiðingar þessara aðferða er kannað enn frekar í: skilgreiningar á fjölþátta tölfræði greiningu á hreyfanleika, skilgreiningar á nýtingu þrívíddarprentunar við undirbúning skurðaðgerða, modeling craniofacial electromyography og tölfræðilegir útreikningar á brotlíkum beinstoðtækja fyrir aðgerð. Niðurstöður þessara aðgerða hafa leitt í ljós möguleika og hindranir tækninnar sem nú er notuð og hjálpað til við að auðga flóruna m.a. með nýstárlegum leiðum til að greina brotlíkur þegar beinagrindarstoðtækjum er komið fyrir við lærlegg sem er brotinn eða í brothættu. Að koma upp staðli fyrir aðferðir sem beitt er við módelgerð myndi flýta mikið fyrir því að þessar aðferðir finni praktísk hlutverk innan heilbrigðisstofnana., Landspítali Scientific Fund, PI: Paolo Gargiulo, “Bone Modeling in patients undergoing THA”, A-2014-072. Rannís Icelandic Research Fund (Rannsóknasjodur), PI: Paolo Gargiulo, “Clinical evaluation score for Total Hip Arthroplasty planning and postoperative assessment”, 152368-051. Rannís Innovation Fund (Nyskopunarsjodur), PI: Paolo Gargiulo, “Clinical assessment for patients undergoing total hip replacement”. The IRCCS Fondazione Ospedale San Camillo, Venezia, Italia. The European Regional Development Fund -Cross Border Cooperation Programme Slovakia –Austria 2007–2013 (Interreg-IVa), project Mobilität im Alter, MOBIL, N_00033 (partners: Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Austria, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria, and Faculty of Physical Education and Sports, Comenius University in Bratislava, Slovakia). Austrian national co-financing of the Austrian Federal Ministry of Science and Research. Ludwig Boltzmann Society (Vienna, Austria) to CH, SL, HK. The EU Commission Shared Cost Project RISE (Contract n. QLG5-CT-2001-02191) and The Austrian Ministry of Science funds to Prof. Dr. H. Kern Vienna (Austria) covered the clinical costs, the production of customized devices and the international management of the project. The Italian MIUR funds to UC and FC, the Laboratoryof Translational Myology, and the Italian C.N.R. funds to the Institute of Neuroscience, University of Padova, Italy, supported light microscopy, morphometry, and costs of data analyses; Some of the research reported here in was additionally supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health,under award number NIH NIAMS 1R03AR053706-01A2 to ALP. It should be noted that the respective content presented here is solely the responsibility of us,the authors,and does not necessarily represent the official views of the National Institutes of Health.

This paper illustrates the feasibility and utility of combining cranial anatomy and brain function on the same 3D-printed model, as evidenced by a neurosurgical planning case study of a 29-year-old female patient with a low-grade frontal-lobe glioma. We herein report the rapid prototyping methodology utilized in conjunction with surgical navigation to prepare and plan a complex neurosurgery. The method introduced here combines CT and MRI images with DTI tractography, while using various image segmentation protocols to 3D model the skull base, tumor, and five eloquent fiber tracts. This 3D model is rapid-prototyped and coregistered with patient images and a reported surgical navigation system, establishing a clear link between the printed model and surgical navigation. This methodology highlights the potential for advanced neurosurgical preparation, which can begin before the patient enters the operation theatre. Moreover, the work presented here demonstrates the workflow developed at the National University Hospital of Iceland, Landspitali, focusing on the processes of anatomy segmentation, fiber tract extrapolation, MRI/CT registration, and 3D printing. Furthermore, we present a qualitative and quantitative assessment for fiber tract generation in a case study where these processes are applied in the preparation of brain tumor resection surgery., The authors would like to thank the Icelandic Innovation Fund RANNIS, the company Ossur, and the University Hospital Landspitali, for providing financial and technical support to this project., "Peer Reviewed"