Biofilm Removal and Bacterial Reduction Using a Low-Cost Ultrasonic Bath Sonicator with Povidone–Iodine on Polyethylene: An In Vitro Periprosthetic Joint Infection Model

Background: Biofilm formation on polyethylene surfaces contributes significantly to treatment failure in periprosthetic joint infection (PJI). In certain clinical situations, such as discontinued implant systems, replacement polyethylene liners may be unavailable, necessitating more complex revision procedures. This study evaluated the efficacy of a low-cost ultrasonic bath sonicator for biofilm removal and bacterial reduction on polyethylene surfaces, with and without povidone–iodine. Methods: An exploratory in vitro experimental study was performed using twenty ultra-high-molecular-weight polyethylene (UHMWPE) coupons (1 × 1 cm, 3 mm thickness) allocated into five groups (n = 4/group): negative control, positive control, povidone–iodine only (PVP-I), sonication only (SON), and sonication with povidone–iodine (SON+PVP-I). Biofilm formation using Staphylococcus epidermidis was established through an optimized protocol developed from sequential pilot experiments. Residual biofilm was quantified using optical density at 600 nm (OD600), while viable bacterial burden was determined by colony-forming unit counts per milliliter (CFU/mL). Results: SON demonstrated the lowest residual biofilm burden (OD600 = 0.194), whereas no culturable bacteria were detected above the assay detection limit (<10 CFU/mL) in the SON+PVP-I group. SON alone resulted in the greatest reduction in residual biofilm biomass, while the addition of PVP-I was associated with reduced recovery of culturable bacteria. Conclusions: A low-cost ultrasonic bath sonicator effectively reduced residual biofilm biomass on polyethylene surfaces, while no culturable bacteria were detected following combined sonication and povidone–iodine treatment. These findings suggest that sonication and chemical disinfection may provide complementary roles in polyethylene decontamination strategies. However, because of the exploratory study design and non-equivalent bacterial recovery procedures across treatment groups, the bacterial recovery findings should be interpreted cautiously. Further studies are required before clinical application.