The effect of a subcutaneous silicone rubber implant with shallow surface microgrooves on the surrounding tissues in rabbits

It has been suggested that during wound healing microtextured surfaces can alter events at the interface between implant surface surface and surrounding tissues. To investigate this phenomenon, smooth and microtextured silicone rubber implants were implanted subcutaneously in rabbits for 3, 7, 42, and 84 days. The textured implants possessed parallel surface microgrooves and ridges with a width of 2.0, 5.0, and 10.0 microns. All grooves had a depth of approximately 0.5 microns. SEM observation showed fibroblasts, erythrocytes, lymphocytes, macrophages, fibrin, and collagen on all implant surfaces after 3 and 7 days. After 42 and 84 days only little collagen, a small number of fibroblasts, but no inflammatory cells were seen on the implant surfaces. The fibroblasts were not oriented along the surface grooves on all textured surfaces. Three-dimensional reconstruction of CLSM images and LM images showed no significant differences between the thickness of the capsules surrounding the smooth and those surrounding the microgrooved implants. In contrast LM did show a significantly lower number of inflammatory cells and a significantly higher number of blood vessels in the capsules surrounding the microgrooved implants. Differences between the 2.0, 5.0, and 10.0 microns grooved implants were not detected. Our results concerning the capsule thickness suggest that the depth of our grooves was not sufficient to facilitate mechanical interlocking, but the cause for the observed differences in inflammatory response and number of blood vessels remains unclear.