In vitro models of soft tissue damage by implant-associated frictional shear stresses

Silicone Implant Surface Roughness, Friction, and Wear

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 (Ra = 2.7 ± 0.6 μm) resulted in average friction coefficients of μavg = 0.46 ± 0.11 across 1,000 mm of sliding distance and generated 1,304 particles with an average particle diameter of Davg = 8.3 ± 13.1 μm. The "microtextured" implant shell (Ra = 32 ± 7.0 μm) exhibited μavg = 1.20 ± 0.10 and generated 2,730 particles with Davg = 4.7 ± 9.1 μm. The "macrotextured" implant shell (Ra = 80 ± 10 μm) exhibited the highest friction coefficients, μavg = 2.82 ± 0.15 and the greatest number of wear debris particles, 11,699, with an average particle size of Davg = 5.3 ± 3.3 μm. Our data may provide guidance for the design of silicone breast implants with lower surface roughness, lower friction, and smaller quantities of wear debris.