An end effector for use with a surgical stapler comprising: an anvil assembly; and a staple cartridge assembly movable relative to the anvil assembly between an approximated position and a spaced apart position, the staple cartridge assembly defining a plurality of retention slots and a cavity, the staple cartridge assembly including: a plurality of staples disposed in the respective plurality of retention slots; a plurality of pushers configured to eject the plurality of staples through the respective plurality of retention slots; an actuation sled configured for movement along a length of the staple cartridge assembly to sequentially engage the plurality of pushers to eject the plurality of staples through the respective plurality of retention slots, the actuation sled including a first knife blade; a surgical buttress material configured to be supported on a tissue facing surface of the staple cartridge assembly; a suture including opposing ends securely attached to opposing lateral sides of the staple cartridge assembly; characterised by an anchoring button configured to be received in the cavity of the staple cartridge assembly such that a portion of the suture is supported in the cavity so as to be severed by the first knife blade of the actuation sled when the actuation sled is advanced distally. an anvil assembly; and a staple cartridge assembly movable relative to the anvil assembly between an approximated position and a spaced apart position, the staple cartridge assembly defining a plurality of retention slots and a cavity, the staple cartridge assembly including: a plurality of staples disposed in the respective plurality of retention slots; a plurality of pushers configured to eject the plurality of staples through the respective plurality of retention slots; an actuation sled configured for movement along a length of the staple cartridge assembly to sequentially engage the plurality of pushers to eject the plurality of staples through the respective plurality of retention slots, the actuation sled including a first knife blade; a surgical buttress material configured to be supported on a tissue facing surface of the staple cartridge assembly; a suture including opposing ends securely attached to opposing lateral sides of the staple cartridge assembly; characterised by an anchoring button configured to be received in the cavity of the staple cartridge assembly such that a portion of the suture is supported in the cavity so as to be severed by the first knife blade of the actuation sled when the actuation sled is advanced distally. a plurality of staples disposed in the respective plurality of retention slots; a plurality of pushers configured to eject the plurality of staples through the respective plurality of retention slots; an actuation sled configured for movement along a length of the staple cartridge assembly to sequentially engage the plurality of pushers to eject the plurality of staples through the respective plurality of retention slots, the actuation sled including a first knife blade; a surgical buttress material configured to be supported on a tissue facing surface of the staple cartridge assembly; a suture including opposing ends securely attached to opposing lateral sides of the staple cartridge assembly; characterised by an anchoring button configured to be received in the cavity of the staple cartridge assembly such that a portion of the suture is supported in the cavity so as to be severed by the first knife blade of the actuation sled when the actuation sled is advanced distally.