A circular stapling device, comprising: a handle assembly; an elongate body that extends from the handle assembly; a cartridge assembly mounted on a distal end of the elongate body, the cartridge assembly defining an annular containment groove, the cartridge assembly including: a housing; a pusher member supported within the housing and being movable between a first position and a second position; and a fastener cartridge body supported on the housing and having a tissue engaging surface that extends to an annular edge; a circular cartridge buttress member having a body portion and an extension portion, the body portion being supported on the tissue engaging surface of the fastener cartridge body, the extension portion extending from the body portion and over the annular edge of the tissue engaging surface; and a retaining ring member secured within the containment groove over the extension portion of the circular cartridge buttress member to releasably secure the circular cartridge buttress member to the fastener cartridge body; and further comprising a knife assembly, the knife assembly including a primary knife blade and a secondary knife blade, the primary knife blade dimensioned to cut tissue, the secondary knife blade being connected to the pusher member, the secondary knife blade being movable with the pusher member to cut the retaining ring member and relieve a tension that the retaining ring member exerts on the extension portion of the circular cartridge buttress member, the tension being sufficient to maintain the circular cartridge buttress member secured to the fastener cartridge body. a handle assembly; an elongate body that extends from the handle assembly; a cartridge assembly mounted on a distal end of the elongate body, the cartridge assembly defining an annular containment groove, the cartridge assembly including: a housing; a pusher member supported within the housing and being movable between a first position and a second position; and a fastener cartridge body supported on the housing and having a tissue engaging surface that extends to an annular edge; a housing; a pusher member supported within the housing and being movable between a first position and a second position; and a fastener cartridge body supported on the housing and having a tissue engaging surface that extends to an annular edge; a circular cartridge buttress member having a body portion and an extension portion, the body portion being supported on the tissue engaging surface of the fastener cartridge body, the extension portion extending from the body portion and over the annular edge of the tissue engaging surface; and a retaining ring member secured within the containment groove over the extension portion of the circular cartridge buttress member to releasably secure the circular cartridge buttress member to the fastener cartridge body; and further comprising a knife assembly, the knife assembly including a primary knife blade and a secondary knife blade, the primary knife blade dimensioned to cut tissue, the secondary knife blade being connected to the pusher member, the secondary knife blade being movable with the pusher member to cut the retaining ring member and relieve a tension that the retaining ring member exerts on the extension portion of the circular cartridge buttress member, the tension being sufficient to maintain the circular cartridge buttress member secured to the fastener cartridge body.