Hannover, Germany
Hannover, Germany

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Patent
Syntellix AG | Date: 2017-03-01

The subject of the present invention is a method for the surface treatment of a biocorrodable implant by means of electrochemical reactions, comprising the steps of: a) providing an implant of a biocorrodable magnesium alloy; b) introducing the implant into an electrolyte with a pH of 9-13; c) electrochemically treating the surface of the implant, wherein the implant serves as the working electrode and there is also a counterelectrode, and wherein the working electrode is alternately polarized cathodically and anodically, the current density being set to -0.1 to -7 mA/cm2 for the cathodic polarization and to 0.1 to 2 mA/cm2 for the anodic polarization. A corresponding implant is also the subject of the invention.


Reifenrath J.,University of Veterinary Medicine Hannover | Angrisani N.,University of Veterinary Medicine Hannover | Erdmann N.,University of Veterinary Medicine Hannover | Lucas A.,Leibniz University of Hanover | And 7 more authors.
Biomedical Materials (Bristol) | Year: 2013

Magnesium alloys are promising implant materials for use in orthopaedic applications. In the present study, screws made of the Mg-alloy ZEK100 (n = 12) were implanted in rabbit tibiae for four and six weeks, respectively. For degradation analysis, in vivo μ-computed tomography (μCT), a determination of the weight changes and SEM/EDX examinations of the screws were performed. Screw retention forces were verified by uniaxial pull-out tests. Additionally, soft-tissue biocompatibility was estimated using routine histological methods (H&E staining) and the immunohistological characterization of B- and T-cells. After six weeks, a 7.5% weight reduction occurred and, in dependence of the implant surrounding, the volume loss (μCT) reached 9.6% (screw head) and 5.0% for the part of the thread in the marrow cavity. Pull-out forces significantly decreased to 44.4% in comparison with the origin value directly after implantation. Soft tissue reactions were characterized by macrophage and lymphocyte infiltration, whereas T-cells as well as B-cells could be observed. In comparison to MgCa0.8-screws, the degradation rate and inflammatory tissue response were increased and the screw holding power was decreased after six weeks. In conclusion, ZEK100-screws seem to be inferior to MgCa0.8-screws, although their initial strength was more appropriate. © 2013 IOP Publishing Ltd.


Waizy H.,Hannover Medical School | Diekmann J.,Hannover Medical School | Weizbauer A.,Hannover Medical School | Reifenrath J.,University of Veterinary Medicine Hannover | And 4 more authors.
Journal of Biomaterials Applications | Year: 2014

Biodegradable magnesium-based implants are currently being developed for use in orthopedic applications. The aim of this study was to investigate the acute, subacute, and chronic local effects on bone tissue as well as the systemic reactions to a magnesium-based (MgYREZr-alloy) screw containing rare earth elements. The upper part of the screw was implanted into the marrow cavity of the left femora of 15 adult rabbits (New Zealand White), and animals were euthanized 1 week, 12 weeks, and 52 weeks postoperatively. Blood samples were analyzed at set times, and radiographic examinations were performed to evaluate gas formation. There were no significant increased changes in blood values compared to normal levels. Histological examination revealed moderate bone formation with direct implant contact without a fibrous capsule. Histopathological evaluation of lung, liver, intestine, kidneys, pancreas, and spleen tissue samples showed no abnormalities. In summary, our data indicate that these magnesium-based screws containing rare earth elements have good biocompatibility and osteoconductivity without acute, subacute, or chronic toxicity. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.


Ezechieli M.,Hannover Medical School | Ettinger M.,Hannover Medical School | Konig C.,Hannover Medical School | Weizbauer A.,Hannover Medical School | And 5 more authors.
Knee Surgery, Sports Traumatology, Arthroscopy | Year: 2014

Purpose: Degradable magnesium implants have received increasing interest in recent years. In anterior cruciate ligament reconstruction surgery, the well-known osteoconductive effects of biodegradable magnesium alloys may be useful. The aim of this study was to examine whether interference screws made of MgYREZr have comparable biomechanical properties to commonly used biodegradable screws and whether a different thread on the magnesium screw has an influence on the fixation strength.Methods: Five magnesium (MgYREZr-alloy) screws were tested per group. Three different groups with variable thread designs (Designs 1, 2, and 3) were produced and compared with the commercially available bioabsorbable Bioacryl rapid polylactic-co-glycolic acid screw Milagro®. In vitro testing was performed in synthetic bone using artificial ligament fixed by an interference screw. The constructs were pretensioned with a constant load of 60 N for 30 s followed by 500 cycles between 60 N and 250 N at 1 Hz. Construct displacements between the 1st and 20th and the 21st and 500th cycles were recorded. After a 30 s break, a maximum load to failure test was performed at 1 mm/s measuring the maximum pull-out force.Results: The maximum loads to failure of all three types of magnesium interference screws (Design 1: 1,092 ± 133.7 N; Design 2: 1,014 ± 103.3 N; Design 3: 1,001 ± 124 N) were significantly larger than that of the bioabsorbable Milagro® interference screw (786.8 ± 62.5 N) (p < 0.05). However, the greatest maximum load was found with magnesium screw Design 1. Except for a significant difference between Designs 1 and 2, there were no further significant differences among the four groups in displacement after the 20th cycle.Conclusions: Biomechanical testing showed higher pull-out forces for magnesium compared with a commercial polymer screw. Hence, they suggest better stability and are a potential alternative. The thread geometry does not significantly influence the stability provided by the magnesium implants. This study shows the first promising results of a degradable material, which may be a clinical alternative in the future. © 2014 European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA)


Ezechieli M.,Hannover Medical School | Diekmann J.,Hannover Medical School | Weizbauer A.,Hannover Medical School | Becher C.,Hannover Medical School | And 5 more authors.
Journal of Biomaterials Applications | Year: 2014

Degradable magnesium alloys are promising biomaterials for orthopedic applications. The aim of this study was to evaluate the potential effects on both the synovial membrane (synovialis) and the synovial fluid (synovia) of the degradation products of a MgYREZr-pin implanted in the intercondylar femoral notch in a rabbit model. Thirty-six animals were randomized into two groups (MgYREZr or Ti6Al4V alloy) of 18 animals each. Each group was then divided into three subgroups with implantation periods of 1, 4, and 12 weeks, with six animals in each subgroup. The initial inflammatory reaction caused by the surgical trauma declined after 12 weeks of implantation, and elucidated a progressive recovery of the synovial membrane. Compared with control Ti6Al4V pins, there were no significant differences between the groups. However, after 12 weeks, recovery of the synovial membrane was more advanced in the titanium group, in which 92% showed no signs of synovitis, than in the magnesium group. A cytotoxicity test with L929 cells and human osteoblasts (HOB) was also conducted, according to EN ISO 10993-5/12, and no toxic leachable products were observed after 24 h of incubation. In conclusion, the MgYREZr alloy seems to be a suitable material for intra-articular degradable implants. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.


PubMed | Hannover Medical School, Syntellix AG and Leibniz University of Hanover
Type: Journal Article | Journal: Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA | Year: 2014

Degradable magnesium implants have received increasing interest in recent years. In anterior cruciate ligament reconstruction surgery, the well-known osteoconductive effects of biodegradable magnesium alloys may be useful. The aim of this study was to examine whether interference screws made of MgYREZr have comparable biomechanical properties to commonly used biodegradable screws and whether a different thread on the magnesium screw has an influence on the fixation strength.Five magnesium (MgYREZr-alloy) screws were tested per group. Three different groups with variable thread designs (Designs 1, 2, and 3) were produced and compared with the commercially available bioabsorbable Bioacryl rapid polylactic-co-glycolic acid screw MilagroThe maximum loads to failure of all three types of magnesium interference screws (Design 1: 1,092133.7N; Design 2: 1,014103.3N; Design 3: 1,001124N) were significantly larger than that of the bioabsorbable MilagroBiomechanical testing showed higher pull-out forces for magnesium compared with a commercial polymer screw. Hence, they suggest better stability and are a potential alternative. The thread geometry does not significantly influence the stability provided by the magnesium implants. This study shows the first promising results of a degradable material, which may be a clinical alternative in the future.


PubMed | Hannover Medical School, Syntellix AG and Leibniz University of Hanover
Type: Journal Article | Journal: Journal of biomaterials applications | Year: 2014

Degradable magnesium alloys are promising biomaterials for orthopedic applications. The aim of this study was to evaluate the potential effects on both the synovial membrane (synovialis) and the synovial fluid (synovia) of the degradation products of a MgYREZr-pin implanted in the intercondylar femoral notch in a rabbit model. Thirty-six animals were randomized into two groups (MgYREZr or Ti6Al4V alloy) of 18 animals each. Each group was then divided into three subgroups with implantation periods of 1, 4, and 12 weeks, with six animals in each subgroup. The initial inflammatory reaction caused by the surgical trauma declined after 12 weeks of implantation, and elucidated a progressive recovery of the synovial membrane. Compared with control Ti6Al4V pins, there were no significant differences between the groups. However, after 12 weeks, recovery of the synovial membrane was more advanced in the titanium group, in which 92% showed no signs of synovitis, than in the magnesium group. A cytotoxicity test with L929 cells and human osteoblasts (HOB) was also conducted, according to EN ISO 10993-5/12, and no toxic leachable products were observed after 24 h of incubation. In conclusion, the MgYREZr alloy seems to be a suitable material for intra-articular degradable implants.


Seitz J.-M.,Syntellix AG | Lucas A.,Syntellix AG | Kirschner M.,Syntellix AG
JOM | Year: 2016

Magnesium alloys are currently subject to much research for use in biodegradable implant applications. The challenge in this field of material development comprises the design of an alloy that provides adequate mechanical and corrosion properties combined with an excellent biocompatibility. While there are many approaches in current literature only one Mg-based application shows the potential to hit the market. MAGNEZIX® Compression Screws are the world’s first approved/CE-certified magnesium-based implants designed for use in biodegradable osteosyntheses applications in humans. Therefore, this paper focusses on challenges and current clinical results achieved by means of degradable compression screws. Insights into the screws’ process chain and approval processes are given. As these innovative screws have already been on the market for 2 years long-term results based on their use in surgery are discussed. © 2016 The Minerals, Metals & Materials Society


Windhagen H.,Hannover Medical School | Radtke K.,Hannover Medical School | Weizbauer A.,Hannover Medical School | Diekmann J.,Hannover Medical School | And 5 more authors.
BioMedical Engineering Online | Year: 2013

Purpose: Nondegradable steel-and titanium-based implants are commonly used in orthopedic surgery. Although they provide maximal stability, they are also associated with interference on imaging modalities, may induce stress shielding, and additional explantation procedures may be necessary. Alternatively, degradable polymer implants are mechanically weaker and induce foreign body reactions. Degradable magnesium-based stents are currently being investigated in clinical trials for use in cardiovascular medicine. The magnesium alloy MgYREZr demonstrates good biocompatibility and osteoconductive properties. The aim of this prospective, randomized, clinical pilot trial was to determine if magnesium-based MgYREZr screws are equivalent to standard titanium screws for fixation during chevron osteotomy in patients with a mild hallux valgus.Methods: Patients (n=26) were randomly assigned to undergo osteosynthesis using either titanium or degradable magnesium-based implants of the same design. The 6 month follow-up period included clinical, laboratory, and radiographic assessments.Results: No significant differences were found in terms of the American Orthopaedic Foot and Ankle Society (AOFAS) score for hallux, visual analog scale for pain assessment, or range of motion (ROM) of the first metatarsophalangeal joint (MTPJ). No foreign body reactions, osteolysis, or systemic inflammatory reactions were detected. The groups were not significantly different in terms of radiographic or laboratory results.Conclusion: The radiographic and clinical results of this prospective controlled study demonstrate that degradable magnesium-based screws are equivalent to titanium screws for the treatment of mild hallux valgus deformities. © 2013 Windhagen et al.; licensee BioMed Central Ltd.


Patent
Syntellix Ag | Date: 2012-08-28

A method for producing a medical implant, such as a bone screw, a bone nail, a bone pin, a plate, a suture anchor, etc. for fastening soft parts, such as tendons, muscles, and ligaments, to a bone, or in the form of an endoprosthesis or at least a part thereof, from a magnesium alloy having a magnesium fraction of at least 80 wt %, in particular of at least 90 wt %, including the following steps: a) melting the magnesium alloy to obtain an alloy melt, b) atomizing the alloy melt under a protective-gas atmosphere and cooling the atomized alloy melt to below the solidification point thereof in order to obtain an alloy powder, c) shaping the alloy powder by pressing to obtain an alloy green body, d) extruding the alloy green body to obtain a magnesium alloy molded part, and e) producing the medical implant from the magnesium alloy molded part.

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