de Wild, Michael
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de Wild, Michael
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- PublikationThree anchor concepts for rotator cuff repair in standardized physiological and osteoporotic bone: a biomechanical study(Elsevier, 06.10.2019) de Wild, Michael; Dietschy, Alain; Claudio, Rosso; Rosso, Claudio [in: Journal of Shoulder and Elbow Surgery]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationThe new LassoLoop360° technique for biomechanically superior tissue grip(Springer, 2019) Müller, Sebastian; de Wild, Michael [in: Knee Surgery, Sports Traumatology, Arthroscopy]PurposeSuprapectoral tenodesis is a frequently used technique for treating pathologies of the long head of the biceps bra-chii (LHBB) tendon. However, so far, no Gold Standard treatment exist. Hence, the arthroscopic LassoLoop360 (LL360) technique is introduced aiming to provide secure fixation and improved biomechanical properties. It was hypothesized, that the LL360 technique would show superior biomechanical response to cyclic loading and ultimate load-to-failure testing compared to the commonly used simple Lasso Loop (SLL).MethodsTwenty-two porcine superficial flexor digitorum tendons were prepared using a No. 2 suture according to either the SLL or the LL360 technique. Displacement after cyclic loading (1.000 cycles) between 5 and 30 N, ultimate load-to-failure (ULTF), mode of failure as well as the construct stiffness were tested.ResultsSignificantly less displacement was found in the LL360 group (SLL 2.25 ± 0.51 mm; LL360 1.67 ± 0.37 mm; p = 0.01). Ultimate Load to Failure was significantly higher in the LL360 (168.6 ± 29.6 N) as compared to the SLL (124.1 ± 25.8 N, p = 0.02). The LL360 also revealed a significant higher stiffness compared to the SLL (SLL 13.1 ± 0.9 N/mm vs. LL360 19.1 ± 1.0 N/mm, p < 0.001). The most common mode of failure was the suture cutting through the tendon, with a significantly less suture cutting through for the LL360 compared with the SLL (p < 0.05).ConclusionThe LassoLoop360-technique offers superior biomechanical characteristics regarding the tendon-suture-interface compared to the SLL. In the initial healing phase, the suture-tendon-interface is the most vulnerable part of the tendon-suture-anchor construct, the aim of this new technique is to reduce this weakest part of the chain (Ponce et al., Am J Sports Med 39:188–194, 2011). This technique may therefore be beneficial for arthroscopic suprapectoral biceps tenodesis at the entrance of the bicipital groove01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationLattice Microarchitecture for Bone Tissue Engineering from Calcium Phosphate Compared to Titanium(Mary Ann Liebert, 10/2018) Chen, Tse-Hsiang; Ghayor, Chafik; Siegenthaler, Barbara; Schuler, Felix; Rüegg, Jasmine; de Wild, Michael; Weber, Franz E. [in: Tissue Engineering. Part A]Additive manufacturing of bone tissue engineering scaffolds will become a key element for personalized bone tissue engineering in the near future. Several additive manufacturing processes are based on extrusion where the deposition of the filament will result in a three-dimensional lattice structure. Recently, we studied diverse lattice structures for bone tissue engineering realized by laser sintering of titanium. In this work, we used lithography-based ceramic manufacturing of lattice structures to produce scaffolds from tricalcium phosphates (TCP) and compared them in vivo to congruent titanium scaffolds manufactured with the identical computer-aided design data to look for material-based differences in bony healing. The results show that, during a 4-week period in a noncritical-size defect in a rabbit calvarium, both scaffolds with the identical microarchitecture performed equally well in terms of bony regeneration and bony bridging of the defect. A significant increase in both parameters could only be achieved when the TCP-based scaffolds were doped with bone morphogenetic protein-2. In a critical-size defect in the calvarial bone of rabbits, however, the titanium scaffold performed significantly better than the TCP-based scaffold, most likely due to its higher mechanical stability. We conclude that titanium and TCP-based scaffolds of the same microarchitecture perform equally well in terms of bone regeneration, provided the microarchitecture meets the mechanical demand at the site of implantation.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationOsteoconductive Lattice Microarchitecture for Optimized Bone Regeneration(Mary Ann Liebert, 06/2018) de Wild, Michael; Ghayor, Chafik; Zimmermann, Simon; Rüegg, Jasmine; Nicholls, Flora; Schuler, Felix; Chen, Tse-Hsiang; Weber, Franz E. [in: 3D Printing and Additive Manufacturing]Selective laser melting (SLM) is one methodology to realize additive manufacturing and is mainly used to join metal powder in a layer-by-layer manner to produce a solid three-dimensional (3D) object. For bone tissue engineering purposes, scaffolds can readily be designed as 3D data model and realized with titanium known for its excellent osseointegration behavior. The microarchitecture, that is, design with submillimeter features, of additively manufactured scaffolds is in many cases a lattice structure. This study aimed to apply SLM that allows a high degree of microarchitectural freedom to generate lattice structures and to determine the optimal distance between rods and the optimal diameter of rods for osteoconduction (bone ingrowth into scaffolds) and bone regeneration. For the biological readout, diverse SLM-fabricated titanium implants were placed in the calvarium of rabbits and new bone formation and defect bridging were determined after 4 weeks of healing. The results from the middle section of the defects show that with a lattice microarchitecture, the optimal distance between titanium rods is around 0.8 mm and the optimal rod dimension is between 0.3 and 0.4 mm to optimize defect bridging and bone regeneration.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationMechanical anisotropy of titanium scaffolds(De Gruyter, 2017) Weber, Franz E.; de Wild, Michael; Rüegg, Jasmine; Schumacher, Ralf [in: Current Directions in Biomedical Engineering]The clinical performance of an implant, e.g. for the treatment of large bone defects, depends on the implant material, anchorage, surface topography and chemistry, but also on the mechanical properties, like the stiffness. The latter can be adapted by the porosity. Whereas foams show isotropic mechanical properties, digitally modelled scaffolds can be designed with anisotropic behaviour. In this study, we designed and produced 3D scaffolds based on an orthogonal architecture and studied its angle-dependent stiffness. The aim was to produce scaffolds with different orientations of the microarchitecture by selective laser melting and compare the angle-specific mechanical behaviour with an in-silico simulation. The anisotropic characteristics of open-porous implants and technical limitations of the production process were studied.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationMarker for the pre-clinical development of bone substitute materials(De Gruyter, 2017) de Wild, Michael; Zimmermann, Simon; Obrecht, Marcel; Dard, Michel [in: Current Directions in Biomedical Engineering]Thin mechanically stable Ti-cages have been developed for the in-vivo application as X-ray and histology markers for the optimized evaluation of pre-clinical performance of bone graft materials. A metallic frame defines the region of interest during histological investigations and supports the identification of the defect site. This standardization of the procedure enhances the quality of pre-clinical experiments. Different models of thin metallic frameworks were designed and produced out of titanium by additive manufacturing (Selective Laser Melting). The productibility, the mechanical stability, the handling and suitability of several frame geometries were tested during surgery in artificial and in ex-vivo bone before a series of cages was preclinically investigated in the female Göttingen minipigs model. With our novel approach, a flexible process was established that can be adapted to the requirements of any specific animal model and bone graft testing.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationEvaluation of calcium dihydroxide- and silver-coated implants in the rat tibia(SAGE, 02.11.2016) Harrasser, Norbert; de Wild, Michael; Gorkotte, Johannes; Obermeier, Andreas; Feihl, Susanne [in: Journal of Applied Biomaterials & Functional Materials]Silver ions (Ag+) have strong antibacterial effects, and silver-coated materials are in widespread clinical use. However, the application of silver-coated medical devices is not without concerns: its use with direct bone contact is not established, and systemic toxic side effects of released Ag+ have been described. Therefore, alternative bactericidal coatings with a more localized way of acting - e.g., calcium dihydroxide, Ca(OH)2 (CH) - would be advantageous. A new rat model of the animal's tibial metaphysis was developed. In the left proximal tibiae of 36 male Wistar rats, titanium screws were implanted. The screws were coated with hydroxyapatite (HA; 12 animals: group I), low-dosed HA silver (HA-Ag; 12 animals: group II) and CH (12 animals: group III). After 6 weeks, all rats were sacrificed. The implants were evaluated for morphological changes on their surfaces, by light microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy; for osteointegration, by measurement of resistance to removal; and for bacterial colonization, by quantitative culture analysis. Additionally, the tibial bone was investigated histologically for signs of osteomyelitis and sonicated to detect bacterial loads. (i) No microbiological or histological signs of infection could be determined on any of the screws or the surrounding bone. (ii) The bone-implant interface analysis revealed extensive bone formation and direct bone-implant contact on all HA, HA-Ag and HA-CH coated screws. (iii) HA and HA-Ag were partially, and CH was fully, degraded on the screw coating, allowing host bone to osteointegrate.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationA new model of implant-related osteomyelitis in the metaphysis of rat tibiae(BioMed Central, 08.04.2016) Harrasser, Norbert; Gorkotte, Johannes; Obermeier, Andreas; Feihl, Susanne; Straub, Melanie; Slotta-Huspenina, Julia; von Eisenhart-Rothe, Ruediger; Moser, Walter; Gruner, Philipp; de Wild, Michael; Gollwitzer, Hans; Burgkart, Rainer [in: BMC Musculoskeletal Disorders]Animal models serve as an important tool to understand peri-implant infection. Most of the models use high bacterial loads (>104 colony forming units, CFU) to provide high infection rates. Therefore these animals evolve rather similarly, making comparison between groups and statistical analysis possible. On the other hand, to mimic clinical constellation of surgery-related infections the use of low amounts of bacteria would be more advantageous.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationBiocompatible wear-resistant thick ceramic coating(De Gruyter, 2016) de Wild, Michael; Vogt, Nicola; Wozniak, Katarzyna; Salito, Armando [in: Current Directions in Biomedical Engineering]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationPreliminary microstructural investigation of Mg produced by SLM(European Cells and Materials, 2016) Saxer, Sina; Rüegg, Jasmine; Dietschy, Alain; Schumacher, Ralf; de Wild, Michael; Wiese, Björn; Wohlfender, Fabian [in: European Cells and Materials]01A - Beitrag in wissenschaftlicher Zeitschrift
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