Biodegradation of a magnesium alloy implant in the intercondylar femoral notch showed an appropriate response to the synovial membrane in a rabbit model in vivo

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

In vitro corrosion of ZEK100 plates in Hank's Balanced Salt Solution

Background: In recent years magnesium alloys have been intensively investigated as potential resorbable materials with appropriate mechanical and corrosion properties. Particularly in orthopedic research magnesium is interesting because of its mechanical properties close to those of natural bone, the prevention of both stress shielding and removal of the implant after surgery. Methods: ZEK100 plates were examined in this in vitro study with Hank's Balanced Salt Solution under physiological conditions with a constant laminar flow rate. After 14, 28 and 42 days of immersion the ZEK100 plates were mechanically tested via four point bending test. The surfaces of the immersed specimens were characterized by SEM, EDX and XRD. Results: The four point bending test displayed an increased bending strength after 6 weeks immersion compared to the 2 week group and 4 week group. The characterization of the surface revealed the presence of high amounts of O, P and Ca on the surface and small Mg content. This indicates the precipitation of calcium phosphates with low solubility on the surface of the ZEK100 plates. Conclusions: The results of the present in vitro study indicate that ZEK100 is a potential candidate for degradable orthopedic implants. Further investigations are needed to examine the degradation behavior

Evaluating a Novel Class of Biomaterials: Magnesium-Containing Layered Double Hydroxides

Metallic magnesium and compounds such as magnesium hydroxide Mg(OH)2 have been shown to have osteoconductive properties under experimental conditions and are gaining an increasing interest in the field of degradable biomaterials. The application of the compounds as implant coatings could support implant incorporation, resulting in an increased period of use of the implants. A variety of Mg-containing Layered Double Hydroxides (Mg-LDHs) has been synthesized and examined. These materials have been tested in various in vitro and in vivo studies; the latter took place in different sites like in the middle ear or in the condyle of New Zealand White Rabbits. In the latest study newly formed bone could be found around the Mg-Al-CO3-LDH pellets, making it a promising compound for bone-healing applications.DFG/SFB/59

The influence of storage and heat treatment on a magnesium-based implant material: An in vitro and in vivo study

© 2015 Bracht et al. Background: Magnesium alloys are recommended as a potential material for osteosynthesis. It is known that storage-induced property modifications can occur in materials like aluminum. Thus the aim of this study was to analyze the influence of storage durations of up to 48weeks on the biomechanical, structural, and degradation properties of the degradable magnesium alloy LAE442. Methods: Extruded implants (n=104; Ø 2.5mm×25mm) were investigated after storage periods of 0, 12, 24, and 48weeks in three different sub-studies: (I) immediately after the respective storage duration and after an additional (II) 56days of in vitro corrosion in simulated body fluid (SFB), and (III) 48weeks in vivo corrosion in a rabbit model, respectively. In addition, the influence of a T5-heat treatment (206°C for 15h in an argon atmosphere) was tested (n=26; 0week of storage). Evaluation was performed by three-point bending, scanning electron microscopy, radiography, μ-computed tomography, evaluation of the mean grain size, and contrast analysis of precipitations (such as aluminum or lithium). Results: The heat treatment induced a significant reduction in initial stability, and enhanced the corrosion resistance. In vivo experiments showed a good biocompatibility for all implants. During the storage of up to 48weeks, no significant changes occurred in the implant properties. Conclusions: LAE442 implants can be safely used after up to 48weeks of storage

Comparative in vitro study and biomechanical testing of two different magnesium alloys.

In this in vitro study, magnesium plates of ZEK100 and MgCa0.8 alloy similar to common titanium alloy osteosynthesis plates were investigated as degradable biomedical materials with a focus on primary stability. Immersion tests were performed in Hank's Balanced Salt Solution at 37. The bending strength of the samples was determined using the four-point bending test according to ISO 9585:1990. The initial strength of the noncorroded ZEK100 plate was 11% greater than that of the MgCa0.8 plate; both were approximately 65% weaker than a titanium plate. The bending strength was determined after 48 and 96 h of immersion in Hank's Balanced Salt Solution; both magnesium alloys decreased by approximately 7% after immersion for 96 h. The degradation rate and the Mg(2+) release of ZEK100 were lower than those of MgCa0.8. Strong pitting and filiform corrosion were observed in the MgCa0.8 samples after 96 h of immersion. The surface of the ZEK100 plates exhibited only small areas of filiform corrosion. The results of this in vitro study indicate that the ZEK100 alloy may be more suitable for biomedical applications

In vitro corrosion of ZEK100 plates in Hank's Balanced Salt Solution

Abstract Background In recent years magnesium alloys have been intensively investigated as potential resorbable materials with appropriate mechanical and corrosion properties. Particularly in orthopedic research magnesium is interesting because of its mechanical properties close to those of natural bone, the prevention of both stress shielding and removal of the implant after surgery. Methods ZEK100 plates were examined in this in vitro study with Hank's Balanced Salt Solution under physiological conditions with a constant laminar flow rate. After 14, 28 and 42 days of immersion the ZEK100 plates were mechanically tested via four point bending test. The surfaces of the immersed specimens were characterized by SEM, EDX and XRD. Results The four point bending test displayed an increased bending strength after 6 weeks immersion compared to the 2 week group and 4 week group. The characterization of the surface revealed the presence of high amounts of O, P and Ca on the surface and small Mg content. This indicates the precipitation of calcium phosphates with low solubility on the surface of the ZEK100 plates. Conclusions The results of the present in vitro study indicate that ZEK100 is a potential candidate for degradable orthopedic implants. Further investigations are needed to examine the degradation behavior.</p