Anvil assembly with snap backup ring

1. An anvil assembly comprising:

a center rod assembly; and

a head assembly pivotally supported on the center rod assembly between an operative position and a tilted position, the head assembly including:

a housing;

a post extending proximally from the housing and defining a proximal annular groove; and

a backup member operably supported about the post, wherein the backup member is movable from a first position in which a portion of the backup member is positioned to prevent pivotal movement of the head assembly from the operative position to the tilted position, to a second position in which the backup member is positioned to permit pivotal movement of the head assembly from the operative position to a tilted position, the backup member including a first locking feature and a second locking feature receivable within the proximal annular groove of the post to maintain the backup member in the first position.

2. The anvil assembly according to claim 1 , wherein the post further defines a distal annular groove, the first and second locking features being received within the distal annular groove to maintain the backup member in the second position.

3. The anvil assembly according to claim 1 , wherein the center rod assembly includes a center rod having at least one tab, wherein the at least one tab engages the backup member when the backup member is in the first position to maintain the head assembly in the operative position.

4. The anvil assembly according to claim 3 , wherein movement of the backup member from the first position to the second position disengages the backup member from the at least one tab to permit the head assembly to move to the tilted position.

5. The anvil assembly according to claim 1 , wherein the first and second locking features are configured to prevent movement of the backup member from the first position to the second position until a predetermined force has been applied to the backup member.

6. The anvil assembly according to claim 5 , wherein the first and second locking features are configured to flex radially outward when the predetermined force is applied to the backup member.

7. The anvil assembly according to claim 1 , wherein the first and second locking features each include a ridge configured for receipt within the proximal annular groove when the backup member is in the first position and within the distal annular groove when the backup member is in the second position.

8. An anvil assembly comprising:

a center rod assembly including a center rod having at least one tab; and

a head assembly pivotally supported on the center rod assembly between an operative position and a tilted position, the head assembly including:

a housing;

a post extending proximally from the housing; and

a backup member operably supported about the post, wherein the backup member is movable from a first position in which a portion of the backup member is positioned to prevent pivotal movement of the head assembly from the operative position to the tilted position, to a second position in which the backup member is positioned to permit pivotal movement of the head assembly from an operative position to the tilted position, the backup member including a first detent and a second detent configured to engage a proximal surface of the post to maintain the backup member in the first position, wherein the at least one tab engages the backup member when the backup member is in the first position to maintain the head assembly in the operative position.

9. The anvil assembly according to claim 8 , wherein the post defines first and second cutouts for receiving the respective first and second detents when the backup member is in the second position.

10. The anvil assembly according to claim 8 , wherein movement of the backup member from the first position to the second position disengages the backup member from the at least one tab to permit the head assembly to move to the tilted position.

11. The anvil assembly according to claim 8 , wherein the at least one tab engages one of the first and second detents.

12. The anvil assembly according to claim 8 , wherein the first and second detents are configured to prevent movement of the backup member from the first position to the second position until a predetermined force has been applied to the backup member.