The aim of this study was to investigate the differences in the in vivo degradation behaviour of magnesium implants with various grain sizes and damaged surfaces. For this purpose, three different LAE442 magnesium implants were produced: cast, single and double extruded implants, in order to obtain different grain sizes. Furthermore, defects were positioned on the surfaces of some of the single extruded implants. The initial stability was determined. Four pins of each implant material were implanted into rabbits’ tibiae and regularly clinically, radiologically and µ-computed tomographically investigated over a period of 27 weeks. Following explantation, investigations were carried out using stereo and scanning electron microscopy including energy-dispersive X-ray analyses. Weight and strength changes were measured. The double extruded implants possessing the finest grains exhibited the highest initial stability (179.18 N). These implants demonstrated the lowest in vivo corrosion rates (0.0134 mm/year) and the least radiologically visible changes. The highest corrosion rate was computed for the implants possessing damaged surfaces. Radiologically discernible bone changes occurred at almost the same time as implant changes for all groups. Based on these results, the aim should be to produce fine-grained magnesium-based alloys for resorbable implants and to avoid any surface damage.
ThomannMKrauseCBormannD. Comparison of the resorbable magnesium alloys LAE442 und MgCa0.8 concerning their mechanical properties, their progress of degradation and the bone-implant-contact after 12 months implantation duration in a rabbit model. Mater Sci Eng Technol2009; 40: 82–87.
2.
StaigerMPPietakAMHuadmaiJ. Magnesium and its alloys as orthopedic biomaterials: a review. Biomaterials2006; 27: 1728–1734.
3.
HuehnerschulteTAAngrisaniNRittershausD. In vivo corrosion of two novel magnesium alloys ZEK100 and AX30 and their mechanical suitability as biodegradable implants. Materials2011; 4: 1144–1167.
4.
WitteFKaeseVHaferkampH. In vivo corrosion of four magnesium alloys and the associated bone response. Biomaterials2005; 26: 3557–3563.
5.
ZengRDietzelWWitteF. Progress and challenge for magnesium alloys as biomaterials. Adv Eng Mater2008; 10: B3–B14.
6.
ReifenrathJKrauseABormannD. Profound differences in the in-vivo-degradation and biocompatibility of two very similar rare-earth containing Mg-alloys in a rabbit model. Materwiss Werksttech2010; 41: 1054–1061.
7.
HamppCUllmannBReifenrathJ. Research on the biocompatibility of the new magnesium alloy LANd442 – an in vivo study in the rabbit tibia over 26 weeks. Adv Eng Mater2012; 14: B28–B37.
8.
WitteFHortNVogtC. Degradable biomaterials based on magnesium corrosion. Curr Opin Solid State Mater Sci2008; 12: 63–72.
9.
SalgadoAJCoutinhoOPReisRL. Bone tissue engineering: state of the art and future trends. Macromol Biosci2004; 4: 743–765.
10.
HofmannGO. Biodegradable implants in traumatology: a review on the state-of-the-art. Arch Orthop Trauma Surg1995; 114: 123–132.
11.
SongGAtrensA. Understanding magnesium corrosion – a framework for improved alloy performance. Adv Eng Mater2003; 5: 837–858.
12.
YazhongZPanFPengJ. Effect of neodymium on the as-extruded ZK20 magnesium alloy. J Rare Earth2010; 28: 631–635.
13.
TongGLiuHLiuY. Effect of rare earth additions on microstructure and mechanical properties of AZ91 magnesium alloys. T Nonferr Metal Soc2010; 20: 336–340.
14.
Von der HöhNBormannDLucasA. Influence of different surface machining treatments of magnesium-based resorbable implants on the degradation behavior in rabbits. Adv Eng Mater2009; 11: B47–B54.
15.
KannanMBSingh RamanRKWitteF. Influence of circumferential notch and fatigue crack on the mechanical integrity of biodegradable magnesium-based alloy in simulated body fluid. J Biomed Mater Res B Appl Biomater2010; 96: 303–309.
16.
Alvarez-LopezMPeredaMDDel ValleJA. Corrosion behaviour of AZ31 magnesium alloy with different grain sizes in simulated biological fluids. Acta Biomater2009; 6: 1763–1771.
17.
JiangBGaoLHuangG. Effect of extrusion processing parameters on microstructure and mechanical properties of as-extruded AZ31 sheets. T Nonferr Metal Soc2008; 18: 160–164.
18.
ChenYWangQPengJ. Effects of extrusion ratio on the microstructure and mechanical properties of AZ31 Mg alloy. J Mater Process Tech2007; 182: 281–285.
19.
ShahzadMWagnerL. Influence of extrusion parameters on microstructure and texture developments, and their effects on mechanical properties of the magnesium alloy AZ80. Mater Sci Eng2009; 506: 141–147.
20.
WitteFFischerJNellesenJ. In vitro and in vivo corrosion measurements of magnesium alloys. Biomaterials2006; 27: 1013–1018.
21.
KrauseAVon der HöhNBormannD. Degradation behaviour and mechanical properties of magnesium implants in rabbit tibiae. J Mater Sci2010; 45: 624–632.
22.
UllmannBReifenrathJDziubaD. In vivo degradation behaviour of the magnesium alloy LANd442 in rabbit tibiae. Materials2011; 4: 2197–2218.
23.
WitteFFischerJNellesenJ. In vivo corrosion and corrosion protection of magnesium alloy LAE442. Acta Biomater2010; 6: 1792–1799.
24.
MakarGKrugerJ. Corrosion of magnesium. Int Mater Rev1993; 38: 138–153.
25.
SongG. Recent progress in corrosion and protection of magnesium alloys. Adv Eng Mater2005; 7: 563–586.
26.
AtrensALiuMZainalAN. Corrosion mechanism applicable to biodegradable magnesium implants. Mater Sci Eng B: Adv2011; 176: 1609–1636.
27.
ZhangEXuLYuG. In vivo evaluation of biodegradable magnesium alloy bone implant in the first 6 months implantation. J Biomed Mater Res A2009; 90: 882–893.
28.
LiLGaoJWangY. Evaluation of cyto-toxicity and corrosion behavior of alkali-heat-treated magnesium in simulated body fluid. Surf Coat Technol2004; 185: 92–98.
29.
SongYShanDChenR. Biodegradable behaviors of AZ31 magnesium alloys in simulated body fluid. Mater Sci Eng C Mater Biol Appl2009; 29: 1039–1045.
30.
ASTM G31-72:2004. Standard practice for laboratory immersion corrosion testing of metals. American Society for Testing and Materials.
31.
DziubaDMeyer-LindenbergASeitzJ-M. Long term in vivo degradation behaviour and biocompatibility of the magnesium alloy ZEK100 for use as biodegradable bone implant. Acta Biomater. Epub ahead of print 23August2012. DOI: 10.1016/j.actbio.2012.08.028.
32.
LambotteA. L’utilisation du magnesium comme materiel perdu dans l’osteosynthèse. Bull Mém Soc Nat Chir1932; 28: 1325–1334.
33.
McBrideED. Absorbable metal in bone surgery. JAMA1938; 111: 2464–2467.
34.
SugiyamaTPriceJSLanyonLE. Functional adaptation to mechanical loading in both cortical and cancellous bone is controlled locally and is confined to the loaded bones. Bone2010; 46: 314–321.
35.
LambersFMSchulteFAKuhnG. Mouse tail vertebrae adapt to cyclic mechanical loading by increasing bone formation rate and decreasing bone resorption rate as shown by time-lapsed in vivo imaging of dynamic bone morphometry. Bone2011; 49: 1340–1350.
36.
WitteFUlrichHPalmC. Biodegradable magnesium scaffolds: part II: peri-implant bone remodeling. J Biomed Mater Res A2007; 81: 757–765.
37.
KubotaK. Review processing and mechanical properties of fine-grained magnesium alloys. J Mater Sci1999; 34: 2255–2262.
