The In Vitro Performance of Surgical Irrigation Solutions in Preventing Biofilm Formation on Implants

Total joint arthroplasties are widely performed in the United States. Although various intraoperative irrigation solutions have been studied, comprehensive in vitro comparisons of their efficacy in preventing biofilm formation across multiple implant materials remain limited. This study evaluated the effectiveness of nine commercially available irrigation solutions in preventing biofilm formation by Staphylococcus aureus and Pseudomonas aeruginosa on four orthopaedic implant materials under clinically relevant conditions. Cytotoxicity was also assessed by evaluating human dermal fibroblast recovery following exposure.

The solutions tested included a polyhexamethylene biguanide (PHMB)-synergy solution, a benzalkonium chloride (BZK) solution, a PHMB-betaine solution, a chlorhexidine gluconate solution, a povidone-iodine solution, a hypochlorous acid solution, a citric acid solution, a triple antibiotic solution (bacitracin, cefazolin, gentamicin), and normal saline. The testing laboratory was blinded to solution identities. Stainless steel, cobalt-chromium alloy, titanium alloy, and ultrahigh molecular weight polyethylene coupons (n = four per group) were pretreated with each solution for two minutes. After aspiration, bacteria in simulated synovial fluid were added. Following 24-hour incubation at 37° C, adherent bacteria were recovered and quantified. For cytocompatibility, fibroblasts were exposed to selected solutions for two minutes, and then incubated in fresh medium. Cell viability was assessed on days one and five using a colorimetric metabolic activity assay.

The PHMB-synergy and BZK solutions were the most effective in preventing biofilm formation, with microbial levels over 6.0-log lower than controls for both pathogens across all materials. Other solutions showed variable efficacy depending on the material and bacterial strain. A 1:10 dilution of the PHMB-synergy solution supported fibroblast recovery at day five, while the BZK solution remained cytotoxic at the same dilution.

Pretreatment with certain irrigation solutions for two minutes, reflecting clinical use, significantly reduces biofilm formation on orthopaedic implant materials and may help prevent periprosthetic joint infections in total joint arthroplasty.