Pulsatile Lavage Is Not Enough to Remove Implant Biofilm: An In Vitro Evaluation of Sonication Brushing

During periprosthetic joint infection revision surgeries, intraoperative irrigation is performed to clear debris, blood, purulence, and microbes from the surgical wound. Dental evidence suggests motorized agitation is effective in removing established biofilms. The purpose of this study was to investigate how pulsatile irrigation and sonicated brushing affect mature staphylococcal biofilm on real arthroplasty components.

Five identically sized, never implanted tibial base plates (TBPs) underwent keel removal with a wire electrical discharge machine. Implants were passivated in 25% nitric acid, autoclaved, and submerged in Methicillin sensitive Staphylococcus aureus (MSSA) infected tryptic soy broth. Biofilm was grown for 72 hours, with media replaced every 24 hours. Following growth, TBPs were assigned to 6 experimental conditions: control (no treatment), low-speed pulsatile lavage, high-speed pulsatile lavage, sonication brushing, combination of low-speed pulsatile lavage followed by sonication brushing, and combination of high-speed pulsatile lavage followed by sonication brushing. Pulsatile lavage lasted 5 seconds, while sonication brushing lasted 20 seconds using a modified commercial brush. Experiments were performed in sextuplicate. Posttreatment TBPs were either put in a sonication bath to dislodge remaining bacteria to count colony-forming units (CFUs) or stained with crystal violet to quantify residual biofilm biomass.

All mechanical methods significantly reduced CFU counts. Low-speed pulsatile lavage, high-speed pulsatile lavage, sonication brushing, and brushing without sonication reduced CFU counts by 64%, 68%, 87%, and 82%, and reduced biofilm biomass by 74%, 68%, 78%, and 77%, respectively, as compared with controls. The combination of pulsatile lavage and brushing lowered CFU counts by 99%, and biofilm biomass was reduced by 86%. Scanning electron microscope (SEM) imaging confirmed biofilm removal from the locking mechanism by sonication brushing only.

Combining pulsatile lavage and mechanical debridement methods more effectively removes biofilm from implant surfaces compared with either method alone.

Mechanical methods including pulsatile lavage and sonication brushing remove biofilm from orthopaedic implants. Clinicians should be aware of these tools and consider using them.