Disclosed herein are polyurethane polymer matrices with a porosity of from about 20 microns to about 90 microns that are useful in promoting closure and protection of incision sites; supporting the lower pole position of breast implants; and providing a partial or complete covering of breast implants to provide a beneficial interface with host tissue and to reduce the potential for malpositioning or capsular contracture. The disclosed matrices can be seeded with mammalian cells.