Maintz, Michaela
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Maintz, Michaela
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Publikation In situ minimally invasive 3D printing for bone and cartilage regeneration - a scoping review(De Gruyter, 14.09.2024) Maintz, Michaela; Tomooka, Yukiko; Eugster, Manuela; Gerig, Nicolas; Sharma, Neha; Thieringer, Florian M.; Rauter, GeorgAdvancements in personalized medicine, three-dimensional (3D) printing, miniaturization, and robot-assistedsurgery are driving innovation in tissue engineering. A novelapproach, known asin situprinting, focuses on the direct depo-sition of materials at the surgical site. Using thein situprintingapproach, bone and/or cartilage defects can be addressed withhigh precision. Furthermore, highly customized 3D printed tis-sue constructs or implants can be deposited directly insidethe body. Currently, most applications ofin situprinting arelimited to areas near the skin or open surgeries. Even thougha minimally invasive approach would bring clinical benefits,only a few research groups have focused on this field. In thisscoping review, we provide an overview of the current stateofin situminimally invasive 3D printing technology for boneand cartilage regeneration and discuss its advantages and cur-rent challenges.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Case report. One-stage craniectomy and cranioplasty digital workflow for three-dimensional printed polyetheretherketone implant for an extensive skull multilobular osteochondosarcoma in a dog(Frontiers Research Foundation, 29.08.2024) Hobert, Marc; Sharma, Neha; Benzimra, Caroline; Hinden, Sandro; Oevermann, Anna; Maintz, Michaela; Beyer, Michel; Thieringer, Florian; Guevar, JulienObjective: To report a digital workflow for use and long-term outcome of cranioplasty with a 3D-printed patient-specific Polyetheretherketone (PEEK) implant in a 12-y-old German Shepherd dog after surgical removal of an extensive occipital bone multilobular osteochondrosarcoma (MLO). Study design: Retrospective case report. Animal: A 12-year-old neutered female German Shepherd dog was presented with facial deformity, blindness, tetraparesis, and ataxia. Magnetic resonance imaging (MRI) and computed tomography (CT) identified a large skull-based mass extending extra-and intracranially with severe compression of the cerebellum and occipital lobes of the cerebrum. Methods: One-stage decompressive craniectomy using virtual surgical planned 3D-printed craniotomy cutting guides and the Misonix BoneScalpel® and reconstruction with a patient-specific 3D-printed PEEK cranial implant. Results: 3D-printed craniectomy cutting guides allowed an adequate fit of the cranial implant to the original skull. Misonix BoneScalpel® allowed performing a safe and extensive craniectomy. Postoperative CT (8 weeks after surgery) confirmed the PEEK cranial implant to be in place and without implant rejection. Clinically, the neurological examination identified only a right-hind limb delay in proprioception 8 weeks postoperatively, which remained unchanged at 18 months after surgery. Adjunctive treatment included metronomic chemotherapy. Eighteen months after surgery the dog passed away for reasons unrelated to the MLO, no implant-related complications were reported. Conclusion: 3D-printed craniectomy cutting guides, patient-specific PEEK cranial implant, and metronomic chemotherapy can lead to a successful long-term outcome in dogs with extensive skull MLO. Clinical significance: PEEK is an alternative biomaterial that can be used successfully for skull reconstruction.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Evaluation of the dimensional accuracy of robot-guided laser osteotomy in reconstruction with patient-specific implants. An accuracy study of digital high-tech procedures(MDPI, 19.06.2024) Msallem, Bilal; Veronesi, Lara; Beyer, Michel; Halbeisen, Florian S.; Maintz, Michaela; Franke, Adrian; Korn, Paula; Dragu, Adrian; Thieringer, Florian M.Background/Objective: With the rapid advancement in surgical technologies, new workflows for mandibular reconstruction are constantly being evaluated. Cutting guides are extensively employed for defining osteotomy planes but are prone to errors during fabrication and positioning. A virtually defined osteotomy plane and drilling holes in robotic surgery minimize potential sources of error and yield highly accurate outcomes. Methods: Ten mandibular replicas were evaluated after cutting-guided saw osteotomy and robot-guided laser osteotomy following reconstruction with patient-specific implants. The descriptive data analysis summarizes the mean, standard deviation (SD), median, minimum, maximum, and root mean square (RMS) values of the surface comparison for 3D printed models regarding trueness and precision. Results: The saw group had a median trueness RMS value of 2.0 mm (SD ± 1.7) and a precision of 1.6 mm (SD ± 1.4). The laser group had a median trueness RMS value of 1.2 mm (SD ± 1.1) and an equal precision of 1.6 mm (SD ± 1.4). These results indicate that robot-guided laser osteotomies have a comparable accuracy to cutting-guided saw osteotomies, even though there was a lack of statistical significance. Conclusions: Despite the limited sample size, this digital high-tech procedure has been shown to be potentially equivalent to the conventional osteotomy method. Robotic surgery and laser osteotomy offers enormous advantages, as they enable the seamless integration of precise virtual preoperative planning and exact execution in the human body, eliminating the need for surgical guides in the future.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Parameter optimization in a finite element mandibular fracture fixation model using the design of experiments approach(Elsevier, 08/2023) Maintz, Michaela; Msallem, Bilal; de Wild, Michael; Seiler, Daniel; Herrmann, Sven; Feiler, Stefanie; Sharma, Neha; Dalcanale, Federico; Cattin, Philippe; Thieringer, Florian Markus01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Topology-optimized patient-specific osteosynthesis plates(De Gruyter, 02.09.2022) Maintz, Michaela; Seiler, Daniel; Thieringer, Florian M.; de Wild, MichaelPatient-specific osteosynthesis plates can be used to reduce complications related to bone fracture treatment, such as infection, malocclusion and fatigue fractures of plates and screws. However, the implant design process is tedious. We propose a semi-automatic workflow to computationally design patient-specific titanium osteosynthesis plates for mandibular angle fractures. In this process, the plate stiffness is maximized while the mass is reduced. Two plate designs with different numbers of screw holes (implant #1 with four holes, implant #2 with eight holes) were generated with identical topology optimization settings and compared in a finite element model simulating various biomechanical masticatory loads. Differences in von Mises stresses in the implants and screws were observed. The load case of clenching the jaw on the opposite side of the fracture showed the highest stress distribution in implant #1 and higher peak stresses in implant #2. Stress concentrations were observed in sharp corners of the implant and could be reduced using local stress-based topology optimization. We conclude that the design process is an effective method to generate patientspecific implants.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Fabrication and characterization of PCL/HA filament as a 3D printing material using thermal extrusion technology for bone tissue engineering(MDPI, 11.02.2022) Wang, Fengze; Tankus, Esma Bahar; Santarella, Francesco; Rohr, Nadja; Sharma, Neha; Märtin, Sabrina; Michalscheck, Mirja; Cao, Shuaishuai; Maintz, Michaela; Thieringer, Florian M.The most common three-dimensional (3D) printing method is material extrusion, where a pre-made filament is deposited layer-by-layer. In recent years, low-cost polycaprolactone (PCL) material has increasingly been used in 3D printing, exhibiting a sufficiently high quality for consideration in cranio-maxillofacial reconstructions. To increase osteoconductivity, prefabricated filaments for bone repair based on PCL can be supplemented with hydroxyapatite (HA). However, few reports on PCL/HA composite filaments for material extrusion applications have been documented. In this study, solvent-free fabrication for PCL/HA composite filaments (HA 0%, 5%, 10%, 15%, 20%, and 25% weight/weight PCL) was addressed, and parameters for scaffold fabrication in a desktop 3D printer were confirmed. Filaments and scaffold fabrication temperatures rose with increased HA content. The pore size and porosity of the six groups’ scaffolds were similar to each other, and all had highly interconnected structures. Six groups’ scaffolds were evaluated by measuring the compressive strength, elastic modulus, water contact angle, and morphology. A higher amount of HA increased surface roughness and hydrophilicity compared to PCL scaffolds. The increase in HA content improved the compressive strength and elastic modulus. The obtained data provide the basis for the biological evaluation and future clinical applications of PCL/HA material.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation A multi-criteria assessment strategy for 3D printed porous polyetheretherketone (PEEK) patient-specific implants for orbital wall reconstruction(MDPI, 13.08.2021) Sharma, Neha; Welker, Dennis; Aghlmandi, Soheila; Maintz, Michaela; Zeilhofer, Hans-Florian; Honigmann, Philipp; Seifert, Thomas; Thieringer, FlorianPure orbital blowout fractures occur within the confines of the internal orbital wall. Restoration of orbital form and volume is paramount to prevent functional and esthetic impairment. The anatomical peculiarity of the orbit has encouraged surgeons to develop implants with customized features to restore its architecture. This has resulted in worldwide clinical demand for patient-specific implants (PSIs) designed to fit precisely in the patient’s unique anatomy. Material extrusion or Fused filament fabrication (FFF) three-dimensional (3D) printing technology has enabled the fabrication of implant-grade polymers such as Polyetheretherketone (PEEK), paving the way for a more sophisticated generation of biomaterials. This study evaluates the FFF 3D printed PEEK orbital mesh customized implants with a metric considering the relevant design, biomechanical, and morphological parameters. The performance of the implants is studied as a function of varying thicknesses and porous design constructs through a finite element (FE) based computational model and a decision matrix based statistical approach. The maximum stress values achieved in our results predict the high durability of the implants, and the maximum deformation values were under one-tenth of a millimeter (mm) domain in all the implant profile configurations. The circular patterned implant (0.9 mm) had the best performance score. The study demonstrates that compounding multi-design computational analysis with 3D printing can be beneficial for the optimal restoration of the orbital floor.01A - Beitrag in wissenschaftlicher ZeitschriftProjekt
