Circular surgical stapler with mating anvil and shell assembly

1. A surgical fastener applying apparatus comprising:

an elongated body member having proximal and distal ends; and

a fastener applying portion disposed adjacent the distal end of the elongated body member, the fastener applying portion comprising:

a first member defining a central opening, and including an annular first tissue contacting surface, the first tissue contacting surface comprising:

a plurality of slots through which a plurality of surgical fasteners are ejected during firing of the surgical fastener applying apparatus; and

an alignment depression, wherein the alignment depression is spaced apart from the plurality of slots and spaced apart from the central opening; and

a second member movable in relation to the first member, the second member including an annular second tissue contacting surface and a fixed projection extending therefrom, wherein the fixed projection frictionally fits within the alignment depression of the first tissue contacting surface to inhibit relative axial displacement between the first and second members.

2. The surgical stapler according to claim 1 , wherein the first tissue contacting surface includes a plurality of alignment depressions, and the second tissue contacting surface includes a plurality of projections extending therefrom in registration with the plurality of alignment depressions.

3. The surgical stapler according to claim 2 , wherein the plurality of alignment depressions are spaced equidistant from one another, and the plurality of projections are spaced equidistant from one another.

4. The surgical stapler according to claim 1 , wherein at least one alignment depression of the plurality of alignment depressions in the first tissue contracting surface is a hole extending substantially through the first tissue contacting surface.

5. The surgical stapler according to claim 1 , wherein at least one projection of the plurality of projections includes a tapered end.

6. The surgical stapler according to claim 1 , wherein the second tissue contacting surface includes a plurality of pockets configured and dimensioned to receive the surgical fasteners to facilitate formation thereof.

7. The surgical stapler according to claim 1 , wherein the plurality of alignment depressions in the first tissue contacting surface are spaced radially inward of the plurality of slots formed in the first tissue contacting surface, and radially outward of the central opening.

8. A surgical fastener applying apparatus comprising:

an elongated body member having proximal and distal ends; and

a fastener applying portion disposed adjacent the distal end of the elongated body member, the fastener applying portion comprising:

a first member defining a central opening, and including a first tissue contacting surface, the first tissue contacting surface comprising:

a plurality of slots through which a plurality of surgical fasteners are ejected during firing of the surgical fastener applying apparatus; and

a second member movable in relation to the first member, the second member including a second tissue contacting surface, wherein the first tissue contacting surface includes a plurality of alignment depressions, and the second tissue contacting surface includes a plurality of projections extending therefrom, wherein the plurality of projections frictionally fit within the plurality of alignment depressions, wherein the plurality of alignment depressions are spaced equidistant from the central opening.

9. A fastener applying portion for use with a surgical fastener applying apparatus, the fastener applying portion comprising:

a first member defining an annular first tissue contacting surface with a plurality of fastener slots formed therein, the first tissue contacting surface having an alignment depression formed therein spaced apart from the plurality of slots; and

a second member movable in relation to the first member, the second member including an annular second tissue contacting surface, and an alignment protrusion fixedly extending therefrom, wherein the alignment protrusion frictionally fits within the alignment depression in the first tissue contacting surface to inhibit relative axial displacement between the first and second members.

10. The fastener applying portion according to claim 9 , wherein the first tissue contacting surface includes a plurality of alignment depressions spaced equidistant from one another, and the second tissue contacting surface includes a plurality of alignment protrusions extending therefrom in registration with the plurality of alignment depressions.

11. The fastener applying portion according to claim 10 , wherein the plurality of alignment projections extending from the second tissue contacting surface are positioned in diametrical opposition, and the plurality of alignment protrusion in the first tissue contacting surface are positioned in diametrical opposition.

12. The fastener applying portion according to claim 9 , wherein the second member further comprises a plurality of venting apertures.

13. The fastener applying portion according to claim 9 , wherein the alignment protrusion extending from the second tissue contacting surface includes a tapered end.

14. The fastener applying portion according to claim 9 , wherein the second tissue contacting surface further comprises a plurality of fastener forming pockets formed therein.

15. The fastener applying portion according to claim 9 , wherein the alignment depression in the first tissue contacting surface is spaced radially inward of the plurality of slots formed in the first tissue contacting surface, and radially outward of the central opening in the first member.

16. The fastener applying portion according to claim 9 , wherein the alignment depression is a hole extending entirely through the first tissue contacting surface.

17. A method of performing a surgical procedure comprising:

inserting a surgical fastener applying apparatus into an opening in a patient;

positioning the surgical fastener applying apparatus such that target tissue is positioned between first and second members comprising a fastener applying portion of the surgical fastener applying apparatus;

approximating the first and second members of the fastener applying portion such that a projection fixedly extending from an annular second tissue contacting surface of the second member frictionally fits within a corresponding alignment depression formed in an annular first tissue contacting surface of the first member to inhibit relative axial displacement between the first and second members, wherein the depression is spaced from a plurality of slots formed in the first tissue contacting surface of the first member, and from a central opening defined in the first member; and

firing the surgical fastener applying apparatus to eject a plurality of surgical fasteners through the plurality of slots formed in the first tissue contacting surface of the first member into the target tissue positioned between the first and second members of the fastener applying portion.

18. The method according to claim 17 , wherein approximating the first and second members includes inserting a plurality of projections extending from the second tissue contacting surface of the second member into a corresponding plurality of alignment depressions formed in the first tissue contacting surface of the first member.