@article{AkbariShandizBoulosSavarssonetal.2018, author = {Akbari Shandiz, Mohsen and Boulos, Paul and S{\ae}varsson, Stefan and Ramm, Heiko and Fu, Chun Kit and Miller, Stephen and Zachow, Stefan and Anglin, Carolyn}, title = {Changes in Knee Shape and Geometry Resulting from Total Knee Arthroplasty}, volume = {232}, journal = {Journal of Engineering in Medicine}, number = {1}, doi = {10.1177/0954411917743274}, pages = {67 -- 79}, year = {2018}, abstract = {Changes in knee shape and geometry resulting from total knee arthroplasty can affect patients in numerous important ways: pain, function, stability, range of motion, and kinematics. Quantitative data concerning these changes have not been previously available, to our knowledge, yet are essential to understand individual experiences of total knee arthroplasty and thereby improve outcomes for all patients. The limiting factor has been the challenge of accurately measuring these changes. Our study objective was to develop a conceptual framework and analysis method to investigate changes in knee shape and geometry, and prospectively apply it to a sample total knee arthroplasty population. Using clinically available computed tomography and radiography imaging systems, the three-dimensional knee shape and geometry of nine patients (eight varus and one valgus) were compared before and after total knee arthroplasty. All patients had largely good outcomes after their total knee arthroplasty. Knee shape changed both visually and numerically. On average, the distal condyles were slightly higher medially and lower laterally (range: +4.5 mm to -4.4 mm), the posterior condyles extended farther out medially but not laterally (range: +1.8 to -6.4 mm), patellofemoral distance increased throughout flexion by 1.8-3.5 mm, and patellar thickness alone increased by 2.9 mm (range: 0.7-5.2 mm). External femoral rotation differed preop and postop. Joint line distance, taking cartilage into account, changed by +0.7 to -1.5 mm on average throughout flexion. Important differences in shape and geometry were seen between pre-total knee arthroplasty and post-total knee arthroplasty knees. While this is qualitatively known, this is the first study to report it quantitatively, an important precursor to identifying the reasons for the poor outcome of some patients. Using the developed protocol and visualization techniques to compare patients with good versus poor clinical outcomes could lead to changes in implant design, implant selection, component positioning, and surgical technique. Recommendations based on this sample population are provided. Intraoperative and postoperative feedback could ultimately improve patient satisfaction.}, language = {en} } @article{SaevarssonSharmaAmirietal.2012, author = {Saevarsson, Stefan and Sharma, Gulshan and Amiri, Shahram and Montgomery, Sigrun and Ramm, Heiko and Lichti, Derek and Lieck, Robert and Zachow, Stefan and Anglin, Carolyn}, title = {Radiological method for measuring patellofemoral tracking and tibiofemoral kinematics before and after total knee replacement}, volume = {1}, journal = {Bone and Joint Research}, number = {10}, doi = {10.1302/2046-3758.110.2000117}, pages = {263 -- 271}, year = {2012}, language = {en} } @article{HildebrandtGoubergritsHepptetal.2013, author = {Hildebrandt, Thomas and Goubergrits, Leonid and Heppt, Werner and Bessler, Stefan and Zachow, Stefan}, title = {Evaluation of the Intranasal Flow Field through Computational Fluid Dynamics (CFD)}, volume = {29}, journal = {Journal of Facial and Plastic Surgery}, number = {2}, publisher = {Thieme}, doi = {10.1055/s-0033-1341591}, pages = {93 -- 98}, year = {2013}, language = {en} } @article{SaevarssonSharmaRammetal.2013, author = {Saevarsson, Stefan and Sharma, Gulshan and Ramm, Heiko and Lieck, Robert and Hutchison, Carol and Werle, Jason and Montgomery, Sigrun and Romeo, Carolina and Zachow, Stefan and Anglin, Carolyn}, title = {Kinematic Differences Between Gender Specific And Traditional Knee Implants}, volume = {28}, journal = {The Journal of Arthroplasty}, number = {9}, doi = {10.1016/j.arth.2013.01.021}, pages = {1543 -- 1550}, year = {2013}, language = {en} } @misc{SharmaHoSaevarssonetal.2012, author = {Sharma, Gulshan and Ho, Karen and Saevarsson, Stefan and Ramm, Heiko and Lieck, Robert and Zachow, Stefan and Anglin, Carolyn}, title = {Knee Pose and Geometry Pre- and Post-Total Knee Arthroplasty Using Computed Tomography}, journal = {58th Annual Meeting of the Orthopaedic Research Society (ORS)}, address = {San Francisco, CA}, year = {2012}, language = {en} } @misc{SharmaSaevarssonAmirietal.2012, author = {Sharma, Gulshan and Saevarsson, Stefan and Amiri, Shahram and Montgomery, Sigrun and Ramm, Heiko and Lichti, Derek and Zachow, Stefan and Anglin, Carolyn}, title = {Sequential-Biplane Radiography for Measuring Pre and Post Total Knee Arthroplasty Kinematics}, journal = {58th Annual Meeting of the Orthopaedic Research Society (ORS)}, address = {San Francisco, CA}, year = {2012}, language = {en} } @inproceedings{StefanGulshanSigrunetal.2012, author = {Stefan, Saevarsson and Gulshan, Sharma and Sigrun, Montgomery and Karen, Ho and Ramm, Heiko and Lieck, Robert and Zachow, Stefan and Hutchison, Carol and Jason, Werle and Carolyn, Anglin}, title = {Kinematic Comparison Between Gender Specific and Traditional Femoral Implants}, booktitle = {67th Canadian Orthopaedic Association (COA) Annual Meeting}, year = {2012}, language = {en} } @article{HoSaevarssonRammetal.2012, author = {Ho, Karen and Saevarsson, Stefan and Ramm, Heiko and Lieck, Robert and Zachow, Stefan and Sharma, Gulshan and Rex, Erica and Amiri, Shahram and Wu, Barnabas and Leumann, Andre and Anglin, Carolyn}, title = {Computed tomography analysis of knee pose and geometry before and after total knee arthroplasty}, volume = {45}, journal = {Journal of biomechanics}, number = {13}, doi = {10.1016/j.jbiomech.2012.06.004}, pages = {2215 -- 21}, year = {2012}, language = {en} } @article{XieGruberCrampenetal.2025, author = {Xie, Kunpeng and Gruber, Lennart Johannes and Crampen, Martin and Li, Yao and Ferreira, Andr{\´e} and Tappeiner, Elias and Gillot, Maxime and Schepers, Jan and Xu, Jiangchang and Pankert, Tobias and Beyer, Michel and Shahamiri, Negar and ten Brink, Reinier and Dot, Gauthier and Weschke, Charlotte and van Nistelrooij, Niels and Verhelst, Pieter-Jan and Guo, Yan and Xu, Zhibin and Bienzeisler, Jonas and Rashad, Ashkan and Fl{\"u}gge, Tabea and Cotton, Ross and Vinayahalingam, Shankeeth and Ilesan, Robert and Raith, Stefan and Madsen, Dennis and Seibold, Constantin and Xi, Tong and Berg{\´e}, Stefaan and Nebelung, Sven and Kodym, Oldřich and Sundqvist, Osku and Thieringer, Florian and Lamecker, Hans and Coppens, Antoine and Potrusil, Thomas and Kraeima, Joep and Witjes, Max and Wu, Guomin and Chen, Xiaojun and Lambrechts, Adriaan and Cevidanes, Lucia H Soares and Zachow, Stefan and Hermans, Alexander and Truhn, Daniel and Alves, Victor and Egger, Jan and R{\"o}hrig, Rainer and H{\"o}lzle, Frank and Puladi, Behrus}, title = {Beyond Benchmarks: Towards Robust Artificial Intelligence Bone Segmentation in Socio-Technical Systems}, volume = {299}, journal = {Expert Systems With Applications}, number = {Part D}, doi = {10.1016/j.eswa.2025.130031}, year = {2025}, abstract = {Despite the advances in automated medical image segmentation, AI models still underperform in various clinical settings, challenging real-world integration. In this multicenter evaluation, we analyzed 20 state-of-the-art mandibular segmentation models across 19,218 segmentations of 1,000 clinically resampled CT/CBCT scans. We show that segmentation accuracy varies by up to 25\% depending on socio-technical factors such as voxel size, bone orientation, and patient conditions such as osteosynthesis or pathology. Higher sharpness, isotropic smaller voxels, and neutral orientation significantly improved results, while metallic osteosynthesis and anatomical complexity led to significant degradation. Our findings challenge the common view of AI models as "plug-and-play" tools and suggest evidence-based optimization recommendations for both clinicians and developers. This will in turn boost the integration of AI segmentation tools in routine healthcare.}, language = {en} } @misc{DeuflhardDoesselLouisetal.2008, author = {Deuflhard, Peter and D{\"o}ssel, Olaf and Louis, Alfred and Zachow, Stefan}, title = {Mehr Mathematik wagen in der Medizin}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-10776}, number = {08-25}, year = {2008}, abstract = {Der Artikel gibt einen Einblick in das reiche Feld der Zusammenarbeit zwischen Mathematik und Medizin. Beispielhaft werden drei Erfolgsmodelle dargestellt: Medizinische Bildgebung, mathematische Modellierung und Biosignalverarbeitung im Bereich der Dynamik des Herzens sowie mathematische Modellierung und Simulation in der Krebstherapie Hyperthermie und der Mund-Kiefer-Gesichts-Chirurgie. In allen F{\"a}llen existiert ein Gleichklang der Interessen von Medizin und Mathematik: Beide Disziplinen wollen die Resultate schnell und zuverl{\"a}ssig. F{\"u}r die Klinik heißt das, dass notwendige Rechnungen in m{\"o}glichst kurzer Zeit, und zwar auf dem PC, ablaufen m{\"u}ssen und dass die Resultate so genau und belastbar sein m{\"u}ssen, dass medizinische Entscheidungen darauf aufbauen k{\"o}nnen. F{\"u}r die Mathematik folgt daraus, dass h{\"o}chste Anforderungen an die Effizienz der verwendeten Algorithmen und die darauf aufbauende Software in Numerik und Visualisierung zu stellen sind. Jedes Kapitel endet mit einer Darstellung der Perspektive des jeweiligen Gebietes. Abschließend werden m{\"o}gliche Handlungsoptionen f{\"u}r Politik und Wirtschaft diskutiert.}, language = {de} } @misc{ZilskeLameckerZachow2007, author = {Zilske, Michael and Lamecker, Hans and Zachow, Stefan}, title = {Adaptive Remeshing of Non-Manifold Surfaces}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-9445}, number = {07-01}, year = {2007}, abstract = {We present a unified approach for consistent remeshing of arbitrary non-manifold triangle meshes with additional user-defined feature lines, which together form a feature skeleton. Our method is based on local operations only and produces meshes of high regularity and triangle quality while preserving the geometry as well as topology of the feature skeleton and the input mesh.}, language = {en} } @misc{Zachow1999, type = {Master Thesis}, author = {Zachow, Stefan}, title = {Design and Implementation of a planning system for episthetic surgery}, year = {1999}, language = {en} } @misc{EhlkeRammLameckeretal.2013, author = {Ehlke, Moritz and Ramm, Heiko and Lamecker, Hans and Hege, Hans-Christian and Zachow, Stefan}, title = {Fast Generation of Virtual X-ray Images from Deformable Tetrahedral Meshes}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-41896}, year = {2013}, abstract = {We propose a novel GPU-based approach to render virtual X-ray projections of deformable tetrahedral meshes. These meshes represent the shape and the internal density distribution of a particular anatomical structure and are derived from statistical shape and intensity models (SSIMs). We apply our method to improve the geometric reconstruction of 3D anatomy (e.g.\ pelvic bone) from 2D X-ray images. For that purpose, shape and density of a tetrahedral mesh are varied and virtual X-ray projections are generated within an optimization process until the similarity between the computed virtual X-ray and the respective anatomy depicted in a given clinical X-ray is maximized. The OpenGL implementation presented in this work deforms and projects tetrahedral meshes of high resolution (200.000+ tetrahedra) at interactive rates. It generates virtual X-rays that accurately depict the density distribution of an anatomy of interest. Compared to existing methods that accumulate X-ray attenuation in deformable meshes, our novel approach significantly boosts the deformation/projection performance. The proposed projection algorithm scales better with respect to mesh resolution and complexity of the density distribution, and the combined deformation and projection on the GPU scales better with respect to the number of deformation parameters. The gain in performance allows for a larger number of cycles in the optimization process. Consequently, it reduces the risk of being stuck in a local optimum. We believe that our approach contributes in orthopedic surgery, where 3D anatomy information needs to be extracted from 2D X-rays to support surgeons in better planning joint replacements.}, language = {en} } @inproceedings{GladilinZachowDeuflhardetal.2001, author = {Gladilin, Evgeny and Zachow, Stefan and Deuflhard, Peter and Hege, Hans-Christian}, title = {Validation of a Linear Elastic Model for Soft Tissue Simulation in Craniofacial Surgery}, volume = {4319}, booktitle = {Proc. SPIE Medical Imaging 2001}, editor = {Mun, Seong}, address = {San Diego, USA}, doi = {10.1117/12.428061}, pages = {27 -- 35}, year = {2001}, language = {en} } @inproceedings{GladilinZachowHegeetal.2001, author = {Gladilin, Evgeny and Zachow, Stefan and Hege, Hans-Christian and Deuflhard, Peter}, title = {FE-based heuristic approach for the estimation of person-specific facial mimics}, booktitle = {Proceedings of Euro-Par 2001: 5-th International Symposium on Computer Methods}, address = {Rome, Italy}, year = {2001}, language = {en} } @inproceedings{GladilinZachowHegeetal.2001, author = {Gladilin, Evgeny and Zachow, Stefan and Hege, Hans-Christian and Deuflhard, Peter}, title = {Towards a Realistic Simulation of Individual Facial Mimics}, booktitle = {Vision Modeling and Visualization 2001 (VMV)}, address = {Stuttgart, Germany}, pages = {129 -- 134}, year = {2001}, language = {en} } @inproceedings{ZachowGladilinZeilhoferetal.2001, author = {Zachow, Stefan and Gladilin, Evgeny and Zeilhofer, Hans-Florian and Sader, Robert}, title = {Improved 3D Osteotomy Planning in Cranio-Maxillofacial Surgery}, booktitle = {Proc. Medical Image Computing and Computer-Assisted Intervention (MICCAI 2001)}, address = {Utrecht, The Netherlands}, doi = {10.1007/3-540-45468-3_57}, pages = {473 -- 481}, year = {2001}, language = {en} } @inproceedings{ZachowGladilinZeilhoferetal.2001, author = {Zachow, Stefan and Gladilin, Evgeny and Zeilhofer, Hans-Florian and Sader, Robert}, title = {3D Osteotomieplanung in der MKG-Chirurgie unter Ber{\"u}cksichtigung der r{\"a}umlichen Weichgewebeanordnung}, booktitle = {Rechner- und sensorgest{\"u}tzte Chirurgie, GI Proc. zur SFB 414 Tagung}, address = {Heidelberg}, pages = {217 -- 226}, year = {2001}, language = {en} } @inproceedings{GladilinZachowDeuflhardetal.2001, author = {Gladilin, Evgeny and Zachow, Stefan and Deuflhard, Peter and Hege, Hans-Christian}, title = {A Biomechanical Model for Soft Tissue Simulation in Craniofacial Surgery}, booktitle = {Medical Imaging and Augmented Reality (MIAR)}, address = {Hong Kong, China}, doi = {10.1109/MIAR.2001.930276}, pages = {137 -- 141}, year = {2001}, language = {en} } @inproceedings{GladilinZachowDeuflhardetal.2001, author = {Gladilin, Evgeny and Zachow, Stefan and Deuflhard, Peter and Hege, Hans-Christian}, title = {Virtual Fibers: A Robust Approach for Muscle Simulation}, booktitle = {IX Mediterranean Conference on Medical and Biological Engineering and Computing (MEDICON)}, address = {Pula, Croatia}, pages = {961 -- 964}, year = {2001}, language = {en} }