## 8 Other Antimicrobial Materials  
In addition to antibiotic-loaded bone scaffolds, there are also other antimicrobial biomaterials including bioactive glass [82]. This is a biodegradable, osteeconductive, osteoinductive and osteogenic material that kills bacteria by leaching ionic dissolution products from its surface [83; 84]. This changes the local osmotic pressure and pH such that it is hostile to microbial growth [84]. It has also been shown to be angiogenic _in vitro_[85]. However, disadvantages of bioactive glass include brittleness and a low fracture toughness [86]. Bioactive glass S53P4 has been the focus of a large multinational study of 116 patients across six countries with chronic osteomyelitisitis [87]. This research reported a cure rate of  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Authors** & **Study Type** & **Materials** & **Main Finding(s)** \\ \hline [PERSON] et al., 2017 [76] & _In vitro_ & Bioglas + PLGA + vancomycin & Supported the fewest viable bacteria compared to controls after 24 h of S. aureus culture. Effect was maintained even after 6 cycles of exposure. \\ [PERSON] et al., 2017 [79] & _In vivo_ (rabbits) & Silica microspheres + nano-HA + polyurethane + levofloxacin (lev) & Increased bone formation compared to controls and levofloxacin (lev) & levofloxacin 6- and 12-weeks. After this time, the scaffold began to degrade. \\ [PERSON] et al., 2018 [78] & _In vivo_ (rabbits) & Gelatin + \(\beta\)-TCP + vancomycin & At 8 weeks, the radiological and histopathological severities were significantly better than controls (\(\gamma\).3x and 3.66x respectively). \\ [PERSON] et al., 2019 [80] & _In vitro_ & Silicon-calcium silicate + polycaprolactone + vancomycin (3D-printed) & Observed a two-step, controlled antibiotic release profile - 50\% during the first 40 h, then sustained release of 20\% over the next 6 days. \\ [PERSON] et al., 2019 [81] & _In vitro_ & Silica microspheres + nano-HA + polyurethane + levofloxacin & Observed increased osteogenic differentiation of bone marrow stem cells at 14 days, a lower number of bacterial colony units at 12 days, decreased apoptosis of osteoblast precursors and decreased microbial adhesion compared to controls. \\ [PERSON] et al., 2019 [77] & _In vivo_ (rats) & Silk + nanosilver + gentamicin & Lower colony count at 3 weeks compared to controls. Four of the six cases in this group inhibited bacterial growth completely. \\ \hline \hline \end{tabular}
\end{table}
Table 2: Experimental studies focusing on antibiotic-eluting, composite scaffolds for chronic osteomyelitisitis.  
90% at a median follow-up length of 31 months [87]. There is some evidence that the antibacterial effect of bioactive glass can be further improved by doping them with metal ions such as zinc, strontium or silver [87]. These materials in themselves have antimicrobial properties [88]. In a recent study be [PERSON] et al. (2010), for example, magnesium-containing cements were shown to have intrinsic antimicrobial activity and were sufficient alone, to significantly improve the health state of animals [37]. Other antimicrobials include enzyme-loaded scaffolds and polymeric nanoparticles [89; 90]. The latter is especially notable, as no bacterial resistance was observed towards these materials _in vitro_ after 20 serial passages (1300 bacterial generations) [90]. On the other hand, resistance occurred after only a few passages for clinically relevant antibiotics [90]. The usefulness of nanoparticles in bone tissue engineering has been summarised by several authors [91; 92].