A circular stapling instrument, comprising: an anvil assembly and an annular knife, the anvil assembly comprising an anvil center rod; an anvil head pivotally coupled to the anvil center rod and movable between a first, operative condition and a second, tilted condition, the anvil head including an inner surface having an outer periphery to define a recess therein and a groove extending radially outward from the recess, the groove having a proximal ledge and a distal ledge; and a ring assembly including: a backup member disposed within the recess of the anvil head; and a cut ring nested with the backup member and captured in the groove of the anvil head, wherein the ring assembly is movable within the recess from a proximal position preventing pivotal movement of the anvil head from the first, operative condition, to a distal position permitting pivotal movement of the anvil head to the second, tilted condition, wherein the cut ring includes: an annular inner body portion disposed in the recess of the anvil head; and an annular outer body portion captured between the proximal and distal ledges of the groove of the anvil head, wherein the outer body portion is configured to be disconnected from the inner body portion upon an advancement of the annular knife through the cut ring wherein the inner body portion of the cut ring is supported on the backup member; characterised in that a part of the outer body portion of the cut ring is supported on the backup member with the outer body portion extending radially beyond the backup member and the outer body portion of the cut ring is configured to be dragged proximally upon a retraction of the annular knife due to frictional engagement between an outer surface of the annular knife and an inner peripheral surface of the outer body portion until the outer body portion contacts the proximal ledge, such that the outer body portion and the inner body portion are axially spaced from one another to define a passage. an anvil assembly and an annular knife, the anvil assembly comprising an anvil center rod; an anvil head pivotally coupled to the anvil center rod and movable between a first, operative condition and a second, tilted condition, the anvil head including an inner surface having an outer periphery to define a recess therein and a groove extending radially outward from the recess, the groove having a proximal ledge and a distal ledge; and a ring assembly including: a backup member disposed within the recess of the anvil head; and a cut ring nested with the backup member and captured in the groove of the anvil head, wherein the ring assembly is movable within the recess from a proximal position preventing pivotal movement of the anvil head from the first, operative condition, to a distal position permitting pivotal movement of the anvil head to the second, tilted condition, wherein the cut ring includes: an annular inner body portion disposed in the recess of the anvil head; and an annular outer body portion captured between the proximal and distal ledges of the groove of the anvil head, wherein the outer body portion is configured to be disconnected from the inner body portion upon an advancement of the annular knife through the cut ring a backup member disposed within the recess of the anvil head; and a cut ring nested with the backup member and captured in the groove of the anvil head, wherein the ring assembly is movable within the recess from a proximal position preventing pivotal movement of the anvil head from the first, operative condition, to a distal position permitting pivotal movement of the anvil head to the second, tilted condition, wherein the cut ring includes: an annular inner body portion disposed in the recess of the anvil head; and an annular outer body portion captured between the proximal and distal ledges of the groove of the anvil head, wherein the outer body portion is configured to be disconnected from the inner body portion upon an advancement of the annular knife through the cut ring an annular inner body portion disposed in the recess of the anvil head; and an annular outer body portion captured between the proximal and distal ledges of the groove of the anvil head, wherein the outer body portion is configured to be disconnected from the inner body portion upon an advancement of the annular knife through the cut ring wherein the inner body portion of the cut ring is supported on the backup member; characterised in that a part of the outer body portion of the cut ring is supported on the backup member with the outer body portion extending radially beyond the backup member and the outer body portion of the cut ring is configured to be dragged proximally upon a retraction of the annular knife due to frictional engagement between an outer surface of the annular knife and an inner peripheral surface of the outer body portion until the outer body portion contacts the proximal ledge, such that the outer body portion and the inner body portion are axially spaced from one another to define a passage.