Silicone implant surface roughness, friction, and wear

Some textured silicone breast implants with high average surface roughness ('macrotextured') have been associated with a rare cancer of the immune system, Breast Implant-Associated Anaplastic Large Cell Lymphoma (BIA-ALCL). Silicone elastomer wear debris may lead to chronic inflammation, a key step in the development of this cancer. Here, we model the generation and release of silicone wear debris in the case of a folded implant-implant ('shell-shell') sliding interface for three different types of implants, characterized by their surface roughness. The 'smooth' implant shell with the lowest average surface roughness tested (R-a = 2.7 +/- 0.6 mu m) resulted in average friction coefficients of mu (avg) = 0.46 +/- 0.11 across 1,000 mm of sliding distance and generated 1,304 particles with an average particle diameter of D (avg) = 8.3 +/- 13.1 mu m. The 'microtextured' implant shell (R-a = 32 +/- 7.0 mu m) exhibited mu (avg) = 1.20 +/- 0.10 and generated 2,730 particles with D (avg) = 4.7 +/- 9.1 mu m. The 'macrotextured' implant shell (R-a = 80 +/- 10 mu m) exhibited the highest friction coefficients, mu (avg) = 2.82 +/- 0.15 and the greatest number of wear debris particles, 11,699, with an average particle size of D (avg) = 5.3 +/- 3.3 mu m. Our data may provide guidance for the design of silicone breast implants with lower surface roughness, lower friction, and smaller quantities of wear debris.