SP29. Fabrication Of Positionally Stable Smooth Implants

PURPOSE: Due to the association of BIA-ALCL with textured devices, the FDA recommended the voluntary recall of textured implants. With the recall came the loss of one of the major benefits conferred by the textured surface: positional stability for anatomically shaped implants. To date, there have been limited modifications, such as suture tabs, which typically provide only temporary expander/implant stability. Our group has engineered a novel smooth breast implant surface that promotes tissue ingrowth into macropores, which are 1-4mm smooth indentations along the implant surface. This novel topography facilitates tissue ingrowth into the outer surface of the implant, thereby fixing the implant into position as the implant capsule forms. In this study, we report our early novel macropore breast implant positional stability findings. METHODS: Miniaturized, anatomically shaped 2cc breast implants with variable surface topography were fabricated using polydimethylsiloxane (PDMS). Three-dimensionally printed negative molds were produced using CAD modeling for implant casting. The prototype breast implant surface was molded with macropores to the following variations in width (W), depth (D), and total surface pore count (P): W1D2P22, W2D2P11, W2D2P22, W2D3P22, W4D2P11 (all widths and depths reported in milimeters). Comparison control groups consisted of smooth implant surfaces and textured implant surfaces topographically comparable to commercially available textured surfaces. Four implants per group (n=4) were autoclaved and inserted into a tight subcutaneous pocket on the dorsa of 350-400 g Sprague-Dawley rats. Rats were sacrificed at one-month and three-month time points and the implant-capsule unit was explanted en bloc for both positional analysis, histological analysis, and micro-CT. RESULTS: At the one-month time point, the smooth implant group had a mean positional rotation of 30.8±22° while the textured group had a mean rotation of 7.5±2.8°. The macropore mean positional rotational data at 1 month was the following: W1D2P22 at 10±3.0°, W2D2P11 at 34.2±24.9°, W2D2P22 at 15.8±5.3°, W2D3P22 at 10.8±4.2°, W4D2P11 at 12.5±3.2°. At the 3-month time point, the smooth implant group had a mean positional rotation of 108.9±45.0° while the textured group had a mean rotation of 43.1±15.4°. The macropore mean positional data at 3 months was the following: W1D2P22 at 75±35.0°, W2D2P11 at 70.6±40.7°, W2D2P22 at 40.6±1.2°, W2D3P22 at 35±7.6°, W4D2P11 at 37.5±13.2°. There was no statistically significant difference between macropore and textured implant positional stability at the 3-month time point (p>0.05). Lower stability was observed when the macropore width and pore count was decreased. There were no significant differences in capsule thickness between groups. CONCLUSION: We present an innovative design of a novel smooth implant topography which enhances implant positional stability without using the traditional microtextured surface linked to BIA-ALCL in a rodent subcutaneous implantation model. These promising early in-vivo results have led to follow-on studies to identify the optimal macropore configuration and density that maximizes implant stability.