A Comparison of In-vitro Staphylococcus aureus Growth on Rough and Smooth Titanium Surfaces.

Purpose: The textured titanium surfaces used in many total hip arthroplasty (THA) implants are designed to promote osseointegration. However, these surface types may also facilitate bacterial adherence and risk of infection. This aim of this study is to characterize the bacterial growth and viability on the different titanium surfaces used in THA implants.

Materials and methods: Smooth and rough titanium samples were cleaned, sterilized, and prepared for bacterial testing. Staphylococcus aureus cultures were applied to the samples, incubated to allow for bacterial adherence, and stained to visualize and quantify bacterial coverage using fluorescence imaging and ImageJ software. Student's t-test was used to compare the percentage of bacterial coverage at each timepoint between smooth and rough samples. Finally, scanning electron microscopy (SEM) was used to observe and compare the surface structure and bacterial adherence at a microtopographic level.

Results: Microtopographic differences between surfaces showed extensive irregularities in the rough samples as compared to the uniform grooved surface of the smooth samples. Confocal imaging showed greater bacterial coverage on the rough surfaces compared to smooth ones at all timepoint including 6 hours (7.85% vs. 3.89%, P=0.049), 12 hours (17.68% vs. 9.54%, P=0.0038), and 24 hours (20.77% vs. 13.26%, P=0.0024). SEM images further confirmed more bacterial proliferation on rough titanium surfaces, especially at the 12-hour mark, with evidence of extra-cellular-matrix.

Conclusion: Our findings demonstrate that rough titanium surfaces allow for greater in-vitro S. aureus growth with biofilm formation as early as 24 hours.