Development of Sponge Structure and Casting Conditions for Absorbable Magnesium Bone Implants

Julmi, Stefan; Klose, Christian; Krüger, A.; Wriggers, Peter; Maier, Hans Jürgen

doi:10.1007/978-3-319-51493-2_29

Cited by 6 publications

(7 citation statements)

References 11 publications

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“…Further reasons for the more significant changes in shape and volume losses of p400 compared to p500, could be the rougher and somewhat larger surface area of p400 due to production. 54 A larger and more uneven surface displays a larger contact area of the implant material to the host tissue, which can result in a more rapid degradation. 29,55 A similar situation was described by Von der Höh et al, 56 who investigated Mg implants with different surface structures in rabbit femura.…”

Section: Discussionmentioning

confidence: 99%

Effect of pore size on tissue ingrowth and osteoconductivity in biodegradable Mg alloy scaffolds

Augustin

Feichtner

Waselau

et al. 2022

Journal of Applied Biomaterials & Functional Materials

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Magnesium has mechanical properties similar to those of bone and is being considered as a potential bone substitute. In the present study, two different pore sized scaffolds of the Mg alloy LAE442, coated with magnesium fluoride, were compared. The scaffolds had interconnecting pores of either 400 (p400) or 500 µm (p500). ß-TCP served as control. Ten scaffolds per time group (6, 12, 24, 36 weeks) were implanted in the trochanter major of rabbits. Histological analyses, µCT scans, and SEM/EDX were performed. The scaffolds showed slow volume decreases (week 36 p400: 9.9%; p500: 7.5%), which were accompanied by uncritical gas releases. In contrast, ß-TCP showed accelerated resorption (78.5%) and significantly more new bone inside (18.19 ± 1.47 mm3). Bone fragments grew into p400 (0.17 ± 0.19 mm3) and p500 (0.36 ± 0.26 mm3), reaching the centrally located pores within p500 more frequently. In particular, p400 displayed a more uneven and progressively larger surface area (week 36 p400: 253.22 ± 19.44; p500: 219.19 ± 4.76 mm2). A better osseointegration of p500 was indicated by significantly more trabecular contacts and a 200 µm wide bone matrix being in the process of mineralization and in permanent contact with the scaffold. The number of macrophages and foreign body giant cells were at an acceptable level concerning resorbable biomaterials. In terms of ingrown bone and integrative properties, LAE442 scaffolds could not achieve the results of ß-TCP. In this long-term study, p500 appears to be a biocompatible and more osteoconductive pore size for the Mg alloy LAE442.

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Section: Discussionmentioning

confidence: 99%

Effect of pore size on tissue ingrowth and osteoconductivity in biodegradable Mg alloy scaffolds

Augustin

Feichtner

Waselau

et al. 2022

Journal of Applied Biomaterials & Functional Materials

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“…Specifically, previous results have already shown that the maximum tolerable load within the elastic regime (858 N) of Mg-La2 implants is significantly lower than that of LAE442 implants (1608 N). 11,16 However, this lower value is still sufficient for the implant's location considered within the rabbit's tibia, as the bone is subjected to only a maximum load of 60 N there. 23,24 However, with respect to the degradation behavior, the difference between the alloys is much more crucial.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, the resulting open-pored Mg scaffolds showed sufficient strength for the envisaged application. 11,16 Apparently, an ideal scaffold would promote bone ingrowth behavior, provide sufficient mechanical strength, and degrade after a given time without leaving any critical elements within the body. The objective of the present study is to move one step ahead in this direction by studying three different Mg-based alloys under conditions relevant for the clinical application.…”

Section: Introductionmentioning

confidence: 99%

Magnesium Alloys for Open-Pored Bioresorbable Implants

Maier

Julmi

Behrens

et al. 2020

JOM

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If bone defects occur, the body's own healing mechanism can close them below a critical size; for larger defects, bone autografts are used. These are typically cut from the same person's hip in a second surgery. Consequently, the risk of complications, such as inflammations, rises. To avoid the risks resulting from the second surgery, absorbable, open-pored implants can be used. In the present study, the suitability of different magnesium alloys as absorbable porous bone substitute material has been investigated. Using the investment casting process with its design flexibility, the implant's structure can be adapted to the ideal pore geometry with respect to bone ingrowth behavior. Different magnesium alloys (Mg-La2, LAE442, and ZX61) were studied and rated in terms of their degradation rate, bone ingrowth behavior, biocompatibility, and resorbability of the individual alloying elements.

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“…To produce the porous scaffolds, exact models of the scaffolds were created using the fused deposition modeling process with individual successive layers of wax on a 3D printer (Solidscape, Inc., Merrimack) (Julmi, Klose, Krüger, Wriggers, & Maier, 2017). For the following investment casting process, the resulting single wax cylinders were attached together to a model wax tree.…”

Section: Magnesium Alloy and Scaffold Structurementioning

confidence: 99%

Comparison of two pore sizes of LAE442 scaffolds and their effect on degradation and osseointegration behavior in the rabbit model

et al. 2020

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The magnesium alloy LAE442 emerged as a possible bioresorbable bone substitute over a decade ago. In the present study, using the investment casting process, scaffolds of the Magnesium (Mg) alloy LAE442 with two different and defined pore sizes, which had on average a diameter of 400 μm (p400) and 500 μm (p500), were investigated to evaluate degradation and osseointegration in comparison to a ß‐TCP control group. Open‐pored scaffolds were implanted in both greater trochanter of rabbits. Ten scaffolds per time group (6, 12, 24, and 36 weeks) and type were analyzed by clinical, radiographic and μ‐CT examinations (2D and 3D). None of the scaffolds caused adverse reactions. LAE442 p400 and p500 developed moderate gas accumulation due to the Mg associated in vivo corrosion, which decreased from week 20 for both pore sizes. After 36 weeks, p400 and p500 showed volume decreases of 15.9 and 11.1%, respectively, with homogeneous degradation, whereas ß‐TCP lost 74.6% of its initial volume. Compared to p400, osseointegration for p500 was significantly better at week 2 postsurgery due to more frequent bone‐scaffold contacts, higher number of trabeculae and higher bone volume in the surrounding area. No further significant differences between the two pore sizes became apparent. However, p500 was close to the values of ß‐TCP in terms of bone volume and trabecular number in the scaffold environment, suggesting better osseointegration for the larger pore size.

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Development of Sponge Structure and Casting Conditions for Absorbable Magnesium Bone Implants

Cited by 6 publications

References 11 publications

Effect of pore size on tissue ingrowth and osteoconductivity in biodegradable Mg alloy scaffolds

Effect of pore size on tissue ingrowth and osteoconductivity in biodegradable Mg alloy scaffolds

Magnesium Alloys for Open-Pored Bioresorbable Implants

Comparison of two pore sizes of LAE442 scaffolds and their effect on degradation and osseointegration behavior in the rabbit model

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