J Orthop Res. 2023 Oct 26. doi: 10.1002/jor.25720. Online ahead of print.
Rifampin has been proven to be effective in the treatment of prosthetic infections due to its ability to intercalate into biofilms. The use of rifampin in antibiotic spacers is not well described, which would be especially important in the local periprosthetic environment where parenteral doses have poor penetration. Null hypothesis tests if rifampin use in PMMA cement will show no clinically significant impact on mechanical strength at antibiotic concentrations that remain bactericidal. Test antibiotic cement samples supplemented with 0mg, 30mg, 50mg, 100mg, 150mg or 200mg of rifampin into a standard 40g bag were tested for compression to failure using published ASTM standards. The samples were then inoculated with Pseudomonas aeruginosa and either evaluated for lipo-polysacharide (LPS) presence as a marker of biofilm or tested by elution as the Kirby Bauer assay. Rifampin concentrations of 30mg, and 50mg, showed no statistically different mechanical characteristics to control PMMA (p>0.05). The 100mg sample fell within the acceptable range of compressive strength and had significantly less LPS and bacterial presence compared to control at 12 and 24 hours. The ability of PMMA with 100mg of rifampin to maintain its structural integrity and have significant bacterial inhibition at 12 and 24 hours makes it a great candidate as an antibiotic bone cement additive. PMMA loaded with up to 100mg of rifampin shows promise in the treatment and prevention of PJI for total knee and total hip arthroplasty. This article is protected by copyright. All rights reserved.