Combating orthopedic implant biofilms — SABER (Study on Agitation for Biofilm Eradication and Reduction) evaluates mechanical, sonication, and radiofrequency approaches: a preclinical in vitro study

BACKGROUND AND PURPOSE: Medical devices commonly employed in orthopedic surgery continue to be susceptible to challenging and costly biofilm bacterial infections. We aimed to evaluate the impact of mechanical brushing with sonication and radiofrequency on biofilms grown on 3 metallic alloys commonly utilized in orthopedic implants: titanium, stainless steel, and cobalt-chromium. METHODS: Biofilms of 4 common bacteria encountered in orthopedic infections were grown on 540 metal chips for 3 metal alloy cohorts. The biofilms were treated with sterile saline irrigation, sonication brushing, or radiofrequency sonication brushing to compare against untreated control. Biofilm burden was evaluated both qualitatively and quantitatively with scanning electron microscopy imaging and crystal violet (CV) staining optical density or colony-forming unit measurements, respectively. Parametric, nonparametric, and linear regression analyses for quantitative data were performed. RESULTS: Qualitatively and quantitatively, all interventions showed a strong reduction in biofilm burden of all microbes on all metals. There was a significant decrease in CV-stained biofilms for brushing interventions compared with irrigation alone and controls. Biofilm burden was significantly reduced in all experiments. The untreated control represented 100% biofilm. Irrigation alone reduced biofilm to 44%, while sonication further decreased biofilm to 25%. The most effective method, sonication with radiofrequency, reduced biofilm to 20%. CONCLUSION: Our data shows consistent qualitative and quantitative reduction in biofilm burden with brushing interventions compared with irrigation and control. While further study is warranted, our data suggest that mechanical brushing with sonication and radiofrequency may be beneficial tools in reducing biofilm burden on orthopedic metal implants.