Biocompatibility and degradation behaviour of degradable magnesium sponges coated with bioglass – method establishment within the framework of a pilot study

Abstract

Aim of the present study was to establish methods for the evaluation of biocompatibility and degradation behaviour of coated magnesium sponges in cancellous bone. So bioglass coated sponges of the magnesium alloy AX30 were implanted into the femurs of rabbits for an observation period of 6, 12 and 24 weeks, respectively. In the follow up clinical and radiographical examinations and in vivo l-computed tomographies (XtremeCT) were taken regularly. After euthanasia ex vivo l-computed tomographies (lCT80) and histological examinations were executed. As result the greater trochanter proved to be a suitable implantation site and all coated magnesium sponges were tolerated well. The radiographs showed no development of gas or severe bone alterations. The XtremeCT depicted the proceeding degradation and accumulations of gas, but turned out to be not as meaningful in exact determination of bone and sponge changes. Better results regarding the degradation state of the sponges were provided by the lCT80 at the end of the test. After all implantation periods different sized implant residues and newly formed bone around the implant were found. The histological examinations resulted in new bone formation and a mild, decreasing inflammation. The bone-implant-interface could not be evaluated at all localisations, since the remaining implants partly coiled up during microtome sectioning. In conclusion the chosen methods are suitable for usage in further studies. But supplement of the cutting and grinding method according to Donath is required to examine the bone-implant-compound.Keywords: sponge / bioglass coating / in vivo / magnesium alloy / resorbable / Ziel dieser Studie war die Methodenetablierung zur Untersuchung von Biokompatibilität und Degradationsverhalten von Magnesiumschwämmen mit Beschichtung in spongiösem Knochen. Es wurden bioglasbeschichtete Schwämme der Magnesiumlegierung AX30 für 6, 12 oder 24 Wochen in Kaninchenfemora implantiert. Es folgten regelmäßige klinische und radiologische Untersuchungen, in vivo (XtremeCT) und ex vivo (lCT80) l-Computertomographien und histologische Untersuchungen. Der Trochanter major erwies sich als geeigneter Implantationsort und die beschichteten Magnesiumschwämme als gut verträglich. Die Röntgenaufnahmen zeigten weder Gasentwicklung noch gravierende Knochenveränderungen. Das XtremeCT stellte Degradationsfortschritte und Gas dar, stellte sich aber als wenig aussagekräftig bezüglich der exakten Bestimmung der Umbauvorgänge von Implantat und Knochen heraus. Bessere Ergebnisse bezüglich des Degradationsfortschritts der Schwämme lieferte hingegen das lCT80 am Versuchsende. Nach allen Implantationszeiten wurden unterschiedlich große Schwammresiduen und neu gebildeter Knochen nachgewiesen. Die histologischen Untersuchungen ergaben neben der Knochenneubildung milde, abnehmende Entzündungsreaktionen. Die Knochen-Implantat-Grenzflächen konnten nicht an allen Lokalisationen untersucht werden, da sich das Implantatmaterial während des Schneidevorgangs am Mikrotom z. T. herauslöste. Insgesamt ...

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

“…The animals were randomly divided into scaffold and time groups. According to the study by Lalk et al (2010), two scaffolds (one per hind limb) were implanted per rabbit in the cancellous part of the greater trochanter of the femur (Figure 2a). In all three groups (p400, p500, and ß-TCP) a total of 40 scaffolds were used.…”

“…The corrosion behavior of Mg could be slowed down by adding various elements such as aluminum (Al), zinc (Zn), lithium (Li), and rare earth elements (SE). This resulted in better primary stability with good biocompatibility (Angrisani et al, 2012;Angrisani et al, 2016;Hampp et al, 2013;Höh et al, 2009;Lalk et al, 2013;Lalk, Reifenrath, Rittershaus, Bormann, & Meyer-Lindenberg, 2010;Meyer-Lindenberg et al, 2010;Rossig et al, 2015;Thomann et al, 2009;Witte et al, 2005;Witte et al, 2006;Witte et al, 2010). Compared with Al-Zn alloys (AZ91, AZ31) and an alloy with yttrium and rare earths (WE43) (Witte et al, 2005), the Mg alloy LAE442 (90 wt% Mg, 4 wt% Li, 4 wt % Al, 2 wt%) has proven to be a promising implant in various animal studies with regard to its good mechanical stability and biocompatibility (Angrisani et al, 2012;Angrisani et al, 2016;Hampp et al, 2013;Meyer-Lindenberg et al, 2010;Reifenrath et al, 2010;Rossig et al, 2015;Witte et al, 2005;Witte et al, 2006;Witte et al, 2010).…”

Rare Earth Metals as Alloying Components in Magnesium Implants for Orthopaedic Applications

“…µ-Computed tomography is a non-destructive analysing method to assess changes within the structure of either engineering components or medical implants [2,40,58,59]. It can also be used to evaluate the reactions of the surrounding tissue to implanted orthopaedic devices after in vivo examinations [57,60,61]. However, the laboratory animals have to be sacrificed for these investigations.…”

“…However, the laboratory animals have to be sacrificed for these investigations. To evaluate the proceeding degradation and to perform a proper initial-to-end-value comparison in vivo µ-computed tomography scans have been introduced recently [50,55,57,60,62]. Further they allow for a reduction of laboratory animals as the results after different implantation periods could be gained from the same animal.…”

“…This definition includes the fact that every inserted implant actually could/will influence the surrounding tissue in one or another way and emphasize on the adequacy. The reactions which are described are either foreign body reactions ( [3,57,60,65] or structural changes of the bone [2,57,61]. To assess cellular reactions histological examinations have to be carried out.…”