Compressible knitted adjuncts with varying interconnections

1. A stapling assembly for use with a surgical stapler, comprising:

a cartridge having a plurality of staples disposed therein, the plurality of staples being configured to be deployed into tissue; and

a knitted adjunct configured to be releasably retained on the cartridge such that the adjunct can be attached to tissue by the plurality of staples in the cartridge, the adjunct having a first end, a second end, and a longitudinal axis extending therebetween, the adjunct comprising at least one knitted layer formed of first fibers and at least one core layer formed of second fibers that are interconnected with the first fibers to form a plurality of interconnections, wherein one of the plurality of interconnections differs from at least another one of the plurality of interconnections to provide a variable compression strength;

wherein the one of the plurality of interconnections that differs from the at least another one of the plurality of interconnections differs in at least one of a lateral direction and a longitudinal direction relative to the longitudinal axis of the adjunct.

2. The stapling assembly of claim 1 , wherein the plurality of interconnections includes a first plurality of interconnections and a second plurality of interconnections.

3. A stapling assembly for use with a surgical stapler, comprising:

a cartridge having a plurality of staples disposed therein, the plurality of staples being configured to be deployed into tissue; and

a knitted adjunct configured to be releasably retained on the cartridge such that the adjunct can be attached to tissue by the plurality of staples in the cartridge, the adjunct having a first end, a second end, and a longitudinal axis extending therebetween, the adjunct comprising at least one knitted layer formed of first fibers and at least one core layer formed of second fibers that are interconnected with the first fibers to form a plurality of interconnections, wherein one of the plurality of interconnections differs from at least another one of the plurality of interconnections to provide a variable compression strength;

wherein the plurality of interconnections includes a first plurality of interconnections and a second plurality of interconnections, and wherein the first plurality of interconnections each have a first tightness, and wherein the second plurality of interconnections each have a second tightness that is greater than the first tightness.

4. The stapling assembly of claim 3 , wherein the cartridge includes a slot formed therein and extending along at least a portion of a longitudinal axis thereof, and wherein the first plurality of interconnections are proximate to the slot relative to the second plurality of interconnections.

5. The stapling assembly of claim 2 , wherein the first plurality of interconnections are present in a first amount, and wherein the second plurality of interconnections are present in a second amount that is greater than the first amount.

6. The stapling assembly of claim 1 , wherein the at least one knitted layer includes third fibers that interconnected with the first fibers and second fibers.

7. The stapling assembly of claim 1 , wherein the second fibers are monofilament fibers.

8. The stapling assembly of claim 1 , wherein the at least one knitted layer includes a first knitted layer that is configured to contact the cartridge.

9. The stapling assembly of claim 8 , wherein the at least one knitted layer includes a second knitted layer that is configured to contact tissue, and wherein the at least one core layer is positioned therebetween.

10. The stapling assembly of claim 1 , wherein the core layer further comprises third fibers that are interconnected with the second fibers.

11. A stapling assembly for use with a surgical stapler, comprising:

a cartridge having a plurality of staples disposed therein, the plurality of staples being configured to be deployed into tissue; and

a knitted adjunct configured to be releasably retained on the cartridge such that the adjunct can be attached to tissue by the plurality of staples in the cartridge, the adjunct having a first end, a second end, and a longitudinal axis extending therebetween, wherein the adjunct comprises at least two different compression zones, each compression zone being formed of first fibers and second fibers that are interconnected to each other at knots, wherein the knots of a first compression zone of the at least two different compression zones each have a first knot tightness and the knots of a second compression zone of the at least two different compression zones each have a second knot tightness that is greater than the first knot tightness such that the adjunct has a varying compression strength;

wherein at least one of the first compression zone and the second compression zone includes third fibers that are interconnected to the second fibers.

12. The stapling assembly of claim 11 , wherein the second compression zone is positioned about at least a portion of a perimeter of the adjunct, and wherein the first compression zone is internal to the perimeter.

13. The stapling assembly of claim 11 , the first compression zone has a first fiber density and the second compression zone has a second fiber density that is different than the first fiber density.

14. The stapling assembly of claim 11 , wherein the cartridge includes a slot formed therein and extending along at least a portion of a longitudinal axis thereof, and wherein the first compression zone is configured to at least partially overlap with the slot when the adjunct is attached to the cartridge.

15. The stapling assembly of claim 11 , wherein the second compression zone is configured to at least partially overlap with at least a portion of the plurality of staple when the adjunct is attached to the cartridge.

16. The stapling assembly of claim 11 , wherein the knots of the first compression zone are present therein at a first frequency and the knots of the second compression zone are present therein at a second frequency that is different than the first frequency.

17. A stapling assembly for use with a surgical stapler, comprising:

a cartridge having a plurality of staples disposed therein, the plurality of staples being configured to be deployed into tissue; and

a knitted adjunct configured to be releasably retained on the cartridge such that the adjunct can be attached to tissue by the plurality of staples in the cartridge, the adjunct having a first end, a second end, and a longitudinal axis extending therebetween, the adjunct comprising

a tissue-contacting layer formed of at least first fibers,

a cartridge-contacting layer formed of at least second fibers, and

a core layer disposed between the tissue-contacting layer and the cartridge-contacting layer, the core layer being formed of third fibers that are interconnected with the first fibers at a first tightness and with the second fibers at a second tightness that is different than the first tightness to allow the adjunct to compress in a first predetermined direction and to limit movement in a second direction that differs from the first predetermined direction;

wherein at least one of the tissue-contacting layer and the cartridge-contacting layer includes reinforcing fibers that are knotted to the second fibers to minimize lateral movement of the second fibers relative to the longitudinal axis of the adjunct.

18. The stapling assembly of claim 17 , wherein the first tightness is greater than the second tightness.

19. The stapling assembly of claim 17 , wherein the first tightness is less than the second tightness.