# Biofilm Growth on Different Materials Used in Contemporary Femoral Head Prosthesis: An In Vitro Study

## TL;DR

This study found that the material of femoral head prostheses does not significantly affect bacterial biofilm formation, which is a key cause of joint infections.

## Contribution

The study empirically evaluates biofilm growth on three modern prosthetic materials in vitro, revealing no significant differences in infection risk.

## Key findings

- No statistically significant differences in biofilm formation were observed across cobalt–chrome, oxinium, and ceramic prostheses.
- Biofilms were primarily localized in the taper hole rather than the bearing surface of the prostheses.
- CFU counts for both S. aureus and P. aeruginosa varied by less than one log across materials.

## Abstract

Background/Objectives: Periprosthetic joint infection (PJI) primarily results from bacterial biofilms adhering to prosthetic surfaces, making treatment challenging without prosthesis removal. This in vitro study aims to investigate whether the materials used in contemporary femoral head prosthesis influences bacterial biofilm development. Methods: Femoral head prostheses made of three different materials—cobalt–chrome, oxinium, and ceramic—were inoculated with either Staphylococcus aureus or Pseudomonas aeruginosa in separate experiments, with each pathogen tested independently. The samples were cultured under shaking conditions at 37 °C for 96 h to promote biofilm formation. Scanning electron microscopy (SEM) was used to confirm the presence of biofilms, and adherent biofilms were quantified by counting colony-forming units (CFUs) after sonication. Additionally, crystal violet staining was performed to assess biofilm distribution on the femoral head surfaces. Statistical analyses compared CFU counts across the different materials. Results: The mean CFU counts for S. aureus were 7.6 × 105 ± 9.7 × 104 for cobalt–chrome, 6.9 × 105 ± 3.6 × 105 for oxinium, and 1.1 × 106 ± 3.0 × 105 for ceramic femoral head prostheses. For P. aeruginosa, the CFU counts were 2.3 × 106 ± 7.2 × 105, 3.7 × 106 ± 2.5 × 106, and 2.2 × 106 ± 8.9 × 105, respectively. Regardless of the bacterial strain, differences among the three materials were within one log range, and no statistical significance was observed. While biofilms were confirmed using SEM, limited adherence was observed on the bearing surface, with the biofilm predominantly localized in the taper hole. Conclusions: The findings suggest that the material used in contemporary femoral head prostheses has minimal impact on bacterial biofilm formation. Surgeons’ choice of femoral head prosthesis material should base their material selection on factors other than PJI prevention.