Analysis of the bone ultrastructure around biodegradable Mg–xGd implants using small angle X-ray scattering and X-ray diffraction

Zeller‐Plumhoff, Berit; Malich, Carina; Krüger, Diana; Campbell, G.; Wiese, Björn; Galli, S.; Wennerberg, Ann; Willumeit‐Römer, Regine; Wieland, D. C. Florian

doi:10.1016/j.actbio.2019.11.030

Cited by 33 publications

(15 citation statements)

References 38 publications

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“…This result is in agreement with the literature on bulk bone, where an increase in thickness and length of crystals with age has been reported [30,50] as well as during bone healing [24,44]. However, a recent study that investigated bone formation around Titanium and resorbable screws in rats did not report any differences in platelet thickness with healing nor compared to mature bone [51]. This discrepancy could be explained by their limited sample size, different sample preparation strategies (difficulties in slicing a metal implant), as well as different data analysis approaches.…”

Section: Young and Immature Tissue In The Bone Chambersupporting

confidence: 92%

Spatio-temporal evolution of hydroxyapatite crystal thickness at the bone-implant interface

et al. 2020

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A better understanding of bone nanostructure around the bone-implant interface is essential to improve longevity of clinical implants and decrease failure risks. This study investigates the spatiotemporal evolution of mineral crystal thickness and plate orientation in newly formed bone around the surface of a metallic implant. Standardized coin-shaped titanium implants designed with a bone chamber were inserted into rabbit tibiae for 7 and 13 weeks. Scanning measurements with microfocused small-angle X-ray scattering (SAXS) were carried out on newly formed bone close to the implant and in control mature cortical bone. Mineral crystals were thinner close to the implant (1.8 ± 0.45 nm at 7 weeks and 2.4 ± 0.57 nm at 13 weeks) than in the control mature bone tissue (2.5 ± 0.21 nm at 7 weeks and 2.8 ± 0.35 nm at 13 weeks), with increasing thickness over healing time (+30 % in 6 weeks). These results are explained by younger bone close to the implant, which matures during osseointegration. Thinner mineral crystals parallel to the implant surface within the first 100 µm close to the implant indicate that the implant affects bone ultrastructure close to the implant, potentially due to heterogeneous interfacial stresses, and suggest a longer maturation process of bone tissue and difficulty in binding to the metal. The bone growth kinetics within the bone chamber was derived from the spatio-temporal evolution of bone tissue's nanostructure, coupled with microtomographic imaging. The findings indicate that understanding mineral crystal thickness or plate orientation can improve our knowledge of osseointegration.

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Section: Young and Immature Tissue In The Bone Chambersupporting

confidence: 92%

Spatio-temporal evolution of hydroxyapatite crystal thickness at the bone-implant interface

et al. 2020

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“…While the chemical composition of a surface can have a large impact on the growth properties, this effect is expected to be most pronounced for the case of calcium phosphate surfaces [59]. A recent study using scanning SAXS could not show significant differences in the DOO or mineral particle thickness between different implant materials such as Ti, PEEK, or Mg-Gd alloys [60].…”

Section: Discussionmentioning

confidence: 99%

3D nanoscale analysis of bone healing around degrading Mg implants studied by X-ray scattering tensor tomography

Liebi

Lutz‐Bueno

Guizar‐Sicairos

et al. 2020

Preprint

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The nanostructural adaptation of bone is crucial for its compatibility with orthopedic implants. The bone’s nanostructure determines its mechanical properties, however little is known about its temporal and spatial adaptation in degrading implants. This study presents insights into this adaptation by applying electron microscopy, elemental analysis, and small-angle X-ray scattering tensor-tomography (SASTT). We extend the SASTT reconstruction to multiple radii of the reciprocal space vector q, providing a 3D reciprocal-space map per voxel. Each scattering curve is spatially linked to one voxel in the volume, and properties such as the thickness of the mineral particles are quantified. This reconstruction provides information on nanostructural adaptation during healing around a degrading ZX10 magnesium implant over the course of 18 months, using a sham as control. The nanostructural adaptation process is observed to start with an initially fast interfacial organization towards the implant direction, followed by a substantial reorganization of the volume around the implant, and an adaptation in the later degradation stages. The study sheds light on the complex bone-implant interaction in 3D, allowing a more guided approach towards the design of future implant materials, which are expected to be of great interest for further clinical studies on the bone-implant interaction.TOC text and figureDegrading Magnesium implants are mechanically and chemically well adapted orthopedic implant materials and ensure a gradual load transfer during bone healing due to their degradation. The impact of the implant degradation on the bone nanostructure is however not fully understood. This study unveils the processes 3D and shows different stages of bone healing.

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“…Magnesium implants are often implanted into the tibia or femur of the animal, specifically into the diaphysis of the long bone. [148,149] However, depending on the scientific question different implantation sites are used, such as the epiphysis, metaphysis, or intercondylar notch. [133] Healing times are selected based on the scientific question and bone healing stage under investigation.…”

Section: Ex Vivo Characterizationmentioning

confidence: 99%

Section: Implant Characterization In Vitro and Ex Vivomentioning

confidence: 99%

Utilizing Synchrotron Radiation for the Characterization of Biodegradable Magnesium Alloys—From Alloy Development to the Application as Implant Material

et al. 2021

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Magnesium (Mg)-based alloys are investigated for the use as lightweight structural metals, e.g., in the automotive industry, [1] as biodegradable implant materials [2] and for hydrogen storage. [3] The choice of alloying system and subsequent processing of the material is a crucial factor for the degradation profile of the alloy and its mechanical properties. [4][5][6][7] This review focuses on use of Mg alloys as implant material, with some references to its application as a structural metal.The degradation profile of Mg alloys is of particular importance for their application as implant materials, as a controlled degradation is required to ensure cell viability and implant stability in vivo. [8,9] During the development of Mg alloys for the application as a biodegradable implant, alloying systems are carefully selected and manufactured, with their microstructure being tailored according to specifications by selecting the appropriate processing route. The microstructure and the mechanical properties of the alloy will be evaluated and the alloy is then tested for in vitro degradation in an aqueous environment under physiological conditions (pH %7.4, 37 C, 5% CO 2 , 21% O 2 , 95% rel. humidity) with and without cells to assess its general degradation properties and cell viability. [10] The mechanical properties and degradation profile need to be tailored depending on the application of the implant. Mg alloys for bone support, for example, require mechanical properties close to that of bone. For bone, the average Young's modulus is between 7 and 31 GPa, depending on the type of bone and its hydration state. [11,12] In longitudinal direction, the bone's tensile and compressive ultimate strength have been reported to be between 93 and 135 MPa, and 154 and 205 MPa, respectively. [13,14] Finally, the elongation to failure of the clinically approved MAGNEZIX screw by Syntellix AG (Hanover, Germany) was determined to be 8%. [15] By contrast, Mg alloys designed for the use as stents must possess a minimum ultimate tensile strength of 300 MPa, low yield strength of 200-300 MPa, and higher ductility (min. 15%-18% elongation to failure, preferably 30%) for their successful deployment. [16,17] Finally, in vivo animal experiments are conducted to evaluate the alloy suitability for the translation into the clinic.

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Analysis of the bone ultrastructure around biodegradable Mg–xGd implants using small angle X-ray scattering and X-ray diffraction

Cited by 33 publications

References 38 publications

Spatio-temporal evolution of hydroxyapatite crystal thickness at the bone-implant interface

Spatio-temporal evolution of hydroxyapatite crystal thickness at the bone-implant interface

3D nanoscale analysis of bone healing around degrading Mg implants studied by X-ray scattering tensor tomography

Utilizing Synchrotron Radiation for the Characterization of Biodegradable Magnesium Alloys—From Alloy Development to the Application as Implant Material

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