The aim of this study was to develop a single-layer hybrid organic-inorganic sol-gel coating that is capable of a controlled antibiotic release for cementless hydroxyapatite (HA)-coated titanium orthopaedic prostheses. Coatings containing gentamicin at a concentration of 1.25% weight/volume (wt/vol), similar to that found in commercially available antibiotic-loaded bone cement, were prepared and tested in the laboratory for: kinetics of antibiotic release; activity against planktonic and biofilm bacterial cultures; biocompatibility with cultured mammalian cells; and physical bonding to the material (n = 3 in all tests). The sol-gel coatings and controls were then tested in vivo in a small animal healing model (four materials tested; n = 6 per material), and applied to the surface of commercially pure HA-coated titanium rods.Aims
Methods
Vancomycin is commonly added to acrylic bone cement during revision
arthroplasty surgery. Proprietary cement preparations containing
vancomycin are available, but are significantly more expensive.
We investigated whether the elution of antibiotic from ‘home-made’
cement containing vancomycin was comparable with more expensive
commercially available vancomycin impregnated cement. A total of 18 cement discs containing either proprietary CopalG+V;
or ‘home-made’ CopalR+G with vancomycin added by hand, were made.
Each disc contained the same amount of antibiotic (0.5 g gentamycin,
2 g vancomycin) and was immersed in ammonium acetate buffer in a
sealed container. Fluid from each container was sampled at eight
time points over a two-week period. The concentrations of gentamicin
and vancomycin in the fluid were analysed using high performance
liquid chromatography mass spectrometry.Aims
Materials and Methods
We investigated whether the indentation of bone
cement spacers used in revision of infected joint arthroplasty with a
MacDonald dissector increased the elution of antibiotic The fluid sampled at 72 hours from the indented discs containing
0.17 g gentamicin (0.88% w/w) contained a mean of 113 mcg/ml (90.12
to 143.5) compared with 44.5 mcg/ml (44.02 to 44.90) in the fluid
sampled from the plain discs (p = 0.012). In discs containing 0.33
g gentamicin (1.75% w/w), the concentration eluted from the indented discs
at 72 hours was a mean of 316 mcg/ml (223 to 421) compared with
a mean of 118 mcg/ml (100 to 140) from the plain discs (p <
0.001). At two weeks, these significant differences persisted. At nine
weeks the indented discs eluted a greater concentration for all
gentamicin doses, but the difference was only significant for the
discs containing 0.17 g (0.88% w/w, p = 0.006). However if the area
under the curve is taken as a measure of the total antibiotic eluted,
the indented discs eluted more gentamicin than the plain discs for
the 0.17 g (0.88% w/w, p = 0.031), the 0.25 g (1.41% w/w, p <
0.001) and the 0.33 g (1.75% w/w, p <
0.001) discs. When preparing antibiotic spacers for use in staged revision
arthroplasty surgery we recommend indenting the spacer with a MacDonald
dissector to increase the elution of antibiotic. Cite this article:
