Knitted tissue scaffolds

FIELD

0001Knitted tissue scaffolds and methods for manufacturing the same are provided.

BACKGROUND

0002Surgical staplers are used in surgical procedures to close openings in tissue, blood vessels, ducts, shunts, or other objects or body parts involved in the particular procedure. The openings can be naturally occurring, such as passageways in blood vessels or an internal organ like the stomach, or they can be formed by the surgeon during a surgical procedure, such as by puncturing tissue or blood vessels to form a bypass or an anastomosis, or by cutting tissue during a stapling procedure.

0003Some surgical staplers require a surgeon to select the appropriate staples having the appropriate staple height for the tissue being stapled. For example, a surgeon could select tall staples for use with thick tissue and short staples for use with thin tissue. In some instances, however, the tissue being stapled does not have a consistent thickness and, thus, the staples cannot achieve the desired fired configuration at each staple site. As a result, a desirable seal at or near all of the stapled sites cannot be formed, thereby allowing blood, air, gastrointestinal fluids, and other fluids to seep through the unsealed sites.

0004Further, staples, as well as other objects and materials that can be implanted in conjunction with procedures like stapling, generally lack some characteristics of the tissue in which they are implanted. For example, staples and other objects and materials can lack the natural flexibility of the tissue in which they are implanted, and therefore are unable to withstand the varying intra-tissue pressures at the implantation site. This can lead to undesirable tissue tearing, and consequently leakage, at or near the staple site, and/or leakage between the apposed implant and tissue.

0005Accordingly, there remains a need for improved instruments and methods that address current issues with surgical staplers. Adjunct materials and methods of using the same in surgical methods for tissue sealing are described in <patcit id="pcit0001" dnum="WO2015191277A2"><text>WO 2015/191277 A2</text></patcit>.

SUMMARY

0006The present invention is defined by the features of the independent claim. Embodiments of the invention are defined in the dependent claims.

0007Staple cartridge assemblies for use with a surgical stapling instrument are provided.

0008In one exemplary embodiment, the staple cartridge assembly can include a staple cartridge having a plurality of staples and a cartridge deck, a knitted elastically deformable, bioabsorbable composite scaffold formed of a plurality of fiber materials, wherein the scaffold is configured to mate with the cartridge deck and wherein the staples are deployable through the scaffold into tissue captured against the scaffold. The composite scaffold can include a tissue interaction surface and a cartridge deck interaction surface, and an intermediate layer that can be disposed between the tissue interaction surface and the cartridge deck interaction surface. The tissue interaction surface and the cartridge deck interaction surface can each be on opposite sides of the scaffold and each can have fibers of a first polymer and fibers of a second polymer, where the first polymer fibers can be multifilament fibers. The first polymer fibers can form a structural component of the tissue interaction surface and the cartridge deck interaction surface with a variable stiffness profile over time following implantation. The second polymer fibers can degrade at a rate greater than that of the first polymer fibers without substantially affecting the stiffness profile of the structural component. The intermediate layer can be formed of monofilament fibers that are oriented in a direction that is substantially non-parallel to the cartridge deck. In one aspect, the multifilament fibers can have an average diameter that is greater than a diameter of the monofilament fibers. In another aspect, the scaffold can be configured to apply a stress of at least about 29000 N/m² (3 gf/mm²) to the captured tissue for at least 3 days when the scaffold is in a tissue deployed state.

0009In some aspects, the multifilament fibers can each include the second polymer fibers at a range of about 15% to 85%. In other aspects, the multifilament fibers can each include the second polymer fibers at a range of about 25% to 45%.

0010In some aspects, the second polymer fibers can have a fiber diameter from about 0.005 mm to 0.02 mm. In one aspect, the second polymer fibers can be formed of a copolymer of glycolide and L-lactide.

0011In some aspects, the multifilament fibers can include about 6 to 40 filaments. In one aspect, the filaments are formed of the first polymer fibers. In another aspect, at least one filament is formed of the first polymer fiber and at least one filament is formed of the second polymer fiber.

0012In some aspects, the first polymer fibers can be formed of at least one of poly-L-lactic acid, a copolymer of glycolide and L-lactide, a copolymer of glycolic acid and lactic acid, poly(lactic-co-glycolic acid), poly(lactic acid), polyglycolide, and a copolymer of glycolide, caprolactone, trimethylene carbonate, and lactide.

0013In some aspects, the monofilament fibers can be formed of at least one of polydioxanone, a copolymer of polydioxanone and polyglycolide, a copolymer of lactide and polycaprolactone), a copolymer of glycolide, dioxanone, and trimethylene carbonate, poly(trimethylene carbonate), polyhydroxyalkanoate, and polyglyconate.

0014Scaffolds for use with a surgical staple cartridge are also provided and can include a tissue interaction surface and a cartridge deck interaction surface, and an intermediate layer disposed between the tissue interaction surface and the cartridge deck interaction surface. The tissue interaction surface and a cartridge deck interaction surface can each be on opposite sides of the scaffold and each can have fibers of a first polymer and fibers of a second polymer, where the first polymer fibers can be multifilament fibers. The first polymer fibers can form a structural component of the tissue interaction surface and the cartridge deck interaction surface with a variable stiffness profile over time following implantation. The second polymer fibers can degrade at a rate greater than that of the first polymer fibers without substantially affecting the stiffness profile of the structural component. The intermediate layer being can formed of monofilament fibers that are oriented in a direction that is substantially non-parallel to the cartridge deck. In another aspect, the scaffold can be configured to apply a stress of at least about 29000 N/m² (3 gf/mm²) to the captured tissue for at least 3 days when the scaffold is in a tissue deployed state.

0015In some aspects, the multifilament fibers can have an average diameter that is greater than a diameter of the monofilament fibers. In other aspects, the multifilament fibers can each include the second polymer fibers at a range of about 15% to 85%.

0016In some aspects, the second polymer fibers can have a fiber diameter from about 0.005 mm to 0.02 mm. In one aspect, the second polymer fibers can be formed of a copolymer of glycolide and L-lactide.

0017In some aspects, the multifilament fibers can include about 6 to 40 filaments. In one aspect, at least one filament is formed of the first polymer fiber and at least one filament is formed of the second polymer fiber.

0018In some aspects, the first polymer fibers can be formed of at least one of poly-L-lactic acid, a copolymer of glycolide and L-lactide, a copolymer of glycolic acid and lactic acid, poly(lactic-co-glycolic acid), poly(lactic acid), polyglycolide, and a copolymer of glycolide, caprolactone, trimethylene carbonate, and lactide.

0019In some aspects, the monofilament fibers can be formed of at least one of polydioxanone, a copolymer of polydioxanone and polyglycolide, a copolymer of lactide and polycaprolactone), a copolymer of glycolide, dioxanone, and trimethylene carbonate, poly(trimethylene carbonate), polyhydroxyalkanoate, and polyglyconate.

BRIEF DESCRIPTION OF THE DRAWINGS

0020The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

0021This invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which: <ul id="ul0001" list-style="none"><li><figref idref="f0001">FIG. 1</figref> is a perspective view of one exemplary embodiment of a conventional surgical stapling and severing instrument;</li><li><figref idref="f0002">FIG. 2</figref> is a perspective view of a wedge sled of a staple cartridge of the surgical stapling and severing instrument of <figref idref="f0001">FIG. 1</figref>;</li><li><figref idref="f0002">FIG. 3</figref> is a perspective view of a knife and firing bar ("E-beam") of the surgical stapling and severing instrument of <figref idref="f0001">FIG. 1</figref>;</li><li><figref idref="f0003">FIG. 4</figref> is a longitudinal cross-sectional view of a surgical cartridge that can be disposed within the stapling and severing instrument of <figref idref="f0001">FIG. 1</figref>;</li><li><figref idref="f0003">FIG. 5</figref> is a top view of a staple in an unfired (pre-deployed) configuration that can be disposed within the staple cartridge of the surgical cartridge assembly of <figref idref="f0003">FIG. 4</figref>;</li><li><figref idref="f0004">FIG. 6</figref> is a longitudinal cross-sectional view of an exemplary embodiment of a surgical cartridge assembly having a scaffold attached to a cartridge deck;</li><li><figref idref="f0005">FIG. 7</figref> is a schematic illustrating the scaffold of <figref idref="f0004">FIG. 6</figref> when stapled to tissue;</li><li><figref idref="f0006">FIG. 8A</figref> is a magnified top view of an exemplary embodiment of a scaffold that can be attached to the cartridge deck of the surgical cartridge assembly of <figref idref="f0004">FIG. 6</figref>;</li><li><figref idref="f0007">FIG. 8B</figref> is a magnified cross-sectional view of the scaffold of <figref idref="f0006">FIG. 8A</figref> taken at B-B;</li><li><figref idref="f0007">FIG. 8C</figref> is another magnified cross-sectional view of the scaffold of <figref idref="f0006">FIG. 8A</figref> taken at C-C;</li><li><figref idref="f0008">FIG. 9</figref> is a scanning electron micrograph (SEM) image of the scaffold in <figref idref="f0006 f0007">FIGS. 8A-8C</figref> at 500 µm scale;</li><li><figref idref="f0009">FIG. 10A</figref> is a histopathology image of an implanted scaffold removed at 60 days as discussed in Example 2.</li><li><figref idref="f0009">FIG. 10B</figref> is a magnified view of section 10B in <figref idref="f0009">FIG. 10A</figref>;</li><li><figref idref="f0009">FIG. 11A</figref> is a histopathology image of an implanted scaffold removed at 90 days as discussed in Example 2;</li><li><figref idref="f0009">FIG. 11B</figref> is a magnified view of section 11B in <figref idref="f0009">FIG. 11A</figref>;</li><li><figref idref="f0010">FIG. 12A</figref> is a perspective view of another exemplary embodiment of a scaffold;</li><li><figref idref="f0011">FIG. 12B</figref> is another exemplary embodiment of a staple cartridge assembly having the scaffold shown in <figref idref="f0010">FIG. 12A</figref> attached to a cartridge deck; and</li><li><figref idref="f0012">FIG. 13</figref> is a bottom view of another exemplary embodiment of a scaffold.</li></ul>

DETAILED DESCRIPTION

0022Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the instruments and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the instruments, systems, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention.

0023Further, in the present disclosure, like-named components of the embodiments generally have similar features, and thus within a particular embodiment each feature of each like-named component is not necessarily fully elaborated upon. Additionally, to the extent that linear or circular dimensions are used in the description of the disclosed systems, instruments, and methods, such dimensions are not intended to limit the types of shapes that can be used in conjunction with such systems, instruments, and methods. A person skilled in the art will recognize that an equivalent to such linear and circular dimensions can easily be determined for any geometric shape. Sizes and shapes of the systems and instruments, and the components thereof, can depend at least on the anatomy of the subject in which the systems and instruments will be used, the size and shape of components with which the systems and instruments will be used, and the methods and procedures in which the systems and instruments will be used.

0024It will be appreciated that the terms "proximal" and "distal" are used herein with reference to a user, such as a clinician, gripping a handle of an instrument. Other spatial terms such as "front" and "rear" similarly correspond respectively to distal and proximal. It will be further appreciated that for convenience and clarity, spatial terms such as "vertical" and "horizontal" are used herein with respect to the drawings. However, surgical instruments are used in many orientations and positions, and these spatial terms are not intended to be limiting and absolute.

0025Values or ranges may be expressed herein as "about" and/or from/of "about" one particular value to another particular value. When such values or ranges are expressed, other embodiments disclosed include the specific value recited and/or from/of the one particular value to another particular value. Similarly, when values are expressed as approximations, by the use of antecedent "about," it will be understood that here are a number of values disclosed therein, and that the particular value forms another embodiment. It will be further understood that there are a number of values disclosed therein, and that each value is also herein disclosed as "about" that particular value in addition to the value itself. In embodiments, "about" can be used to mean, for example, within 10% of the recited value, within 5% of the recited value or within 2% of the recited value.

0026For purposes of describing and defining the present teachings, it is noted that unless indicated otherwise, the term "substantially" is utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The term "substantially" is also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

0027Surgical staple cartridge assemblies and methods for manufacturing the same are provided. In general, a staple cartridge assembly is provided having a staple cartridge that includes a cartridge deck with a plurality of staples disposed therein. The staple cartridge assembly also includes a knitted elastically deformable, bioabsorbable scaffold that is configured to releasably mate with the cartridge deck and allow the staples to be deployed therethrough into tissue. The scaffold can be releasably mated to the cartridge deck such that when a staple is deployed from the cartridge deck and into tissue, at least a portion of the scaffold can attach to the tissue captured by the staple. As discussed herein, the scaffold can be configured to compensate for variations in tissue properties, such as variations in the tissue thickness, and/or promote tissue ingrowth when the scaffold is stapled to tissue. For example, the scaffold can be configured to apply a stress of at least about 29000 N/m² (3 gf/mm²) to tissue for at least 3 days when in a tissue deployed state (e.g., when the scaffold is stapled to tissue <i>in vivo</i>)<i>.</i> An exemplary staple cartridge assembly can include a variety of features to facilitate application of a surgical staple, as described herein and illustrated in the drawings. However, a person skilled in the art will appreciate that the staple cartridge assembly can include only some of these features and/or it can include a variety of other features known in the art. The staple cartridge assemblies described herein are merely intended to represent certain exemplary embodiments. Moreover, while the scaffolds are described in connection with surgical staple cartridge assemblies, the scaffolds can be used in connection with any type of surgical instrument.

0028<figref idref="f0001">FIG. 1</figref> illustrates an exemplary surgical stapling and severing instrument 100 suitable for use with an implantable adjunct such as, for example, a scaffold. The surgical stapling and severing instrument 100 can include an anvil 102 which may be repeatedly opened and closed about its pivotal attachment to an elongate staple channel 104. A staple applying assembly 106 may comprise the anvil 102 and the channel 104, wherein the assembly 106 can be proximally attached to an elongate shaft 108 forming an implement portion 110. When the staple applying assembly 106 is closed, or at least substantially closed, the implement portion 110 can present a sufficiently small cross-section suitable for inserting the staple applying assembly 106 through a trocar. While the instrument 100 is configured to staple and sever tissue, surgical instruments configured to staple but not sever tissue is also contemplated herein.

0029In various instances, the staple applying assembly 106 is manipulated by a handle 112 connected to the elongate shaft 108. The handle 112 can include user controls such as a rotation knob 114 that rotates the elongate shaft 108 and the staple applying assembly 106 about a longitudinal axis of the elongate shaft 108 and a closure trigger 116, which can pivot in front of a pistol grip 118 to close the staple applying assembly 106. A closure release button 120 is outwardly presented on the handle 112 when the closure trigger 116 is clamped such that the closure release button 120 can be depressed to unclamp the closure trigger 116 and open the staple applying assembly 106, for example.

0030A firing trigger 122, which can pivot in front of the closure trigger 116, causes the staple applying assembly 106 to simultaneously sever and staple tissue clamped therein. In various instances, multiple firing strokes can be employed using the firing trigger 122 to reduce the amount of force required to be applied by the surgeon's hand per stroke. In certain embodiments, the handle 112 can comprise one or more rotatable indicator wheels such as, for example, rotatable indicator wheel 124 which can indicate the firing progress. A manual firing release lever 126 can allow the firing system to be retracted before full firing travel has been completed, if desired, and, in addition, the firing release lever 126 can allow a surgeon, or other clinician, to retract the firing system in the event that the firing system binds and/or fails.

0031Additional details on the surgical stapling and severing instrument 100 and other surgical stapling and severing instruments suitable for use with the present disclosure are described, for example, in <patcit id="pcit0002" dnum="US9332984B"><text>U.S. Patent No. 9,332,984</text></patcit> and in <patcit id="pcit0003" dnum="US20090090763"><text>U.S. Patent Application Publication No. 2009/0090763</text></patcit>. Further, the surgical stapling and severing instrument need not include a handle, but instead a housing that is configured to couple to a surgical robot, for example, as described in <patcit id="pcit0004" dnum="US68919817" dnum-type="L"><text>U.S. Patent Application No. 15/689,198, filed on August 29, 2017 to Frederick E. Shelton et al.</text></patcit>.

0032With reference to <figref idref="f0002">FIGS. 2 and 3</figref>, a firing assembly such as, for example, firing assembly 228 can be utilized with a surgical stapling and severing instrument, such as instrument 100 in <figref idref="f0001">FIG. 1</figref>, to advance a wedge sled 230 which comprises a plurality of wedges 232 configured to deploy staples from a staple applying assembly, like staple applying assembly 106 in <figref idref="f0001">FIG. 1</figref> into tissue captured between an anvil, like anvil 102 in <figref idref="f0001">FIG. 1</figref> and an elongate staple channel, like channel 104 in <figref idref="f0001">FIG. 1</figref>. Furthermore, an E-beam 233 at a distal portion of the firing assembly 228 may fire the staples from the staple applying assembly as well as position the anvil relative to the elongate staple channel during firing. The E-beam 233 includes a pair of top pins 234, a pair of middle pins 236 which may follow portion 238 of the wedge sled 230, and a bottom pin or foot 240, as well as a sharp cutting edge 242, which can be configured to sever the captured tissue as the firing assembly 228 is advanced distally. In addition, integrally formed and proximally projecting top guide 244 and middle guide 246 bracketing each vertical end of the cutting edge 242 may further define a tissue staging area 248 assisting in guiding tissue to the sharp cutting edge 242 prior to being severed. The middle guide 246 may also serve to engage and fire the staple applying assembly by abutting a stepped central member 250 of the wedge sled 230 that effects staple formation by the staple applying assembly.

0033Referring to <figref idref="f0003">FIG. 4</figref>, a staple cartridge 400 can be utilized with a surgical stapling and severing instrument, like surgical stapling and severing instrument 100 in <figref idref="f0001">FIG. 1</figref>, and can include a cartridge deck 402 and a plurality of staple cavities 404. A staple 406, for example, can be removably positioned in each staple cavity 404. The staple 406 in a unfired (pre-deployed) configuration is shown in more detail in <figref idref="f0003">FIG. 5</figref>. The staple cartridge 400 can also include a longitudinal channel that can be configured to receive a firing and/or cutting member, e.g., an E-beam, like E-beam 233 in <figref idref="f0002">FIG. 3</figref>.

0034Each staple 406 can comprise a crown (base) 406_C and one or more legs 406_L extending from the crown 406_C. Prior to the staples 406 being deployed, the crowns 406_C of the staples 406 can be supported by staple drivers 408 positioned within the staple cartridge 400 and, concurrently, the legs 406_L of the staples 406 can be at least partially contained within the staple cavities 404. Further, the staple legs 406_L of the staples 406 can extend beyond the tissue-contacting surface 410 of the staple cartridge 400 when the staples 406 are in their unfired positions. In certain instances, as shown in <figref idref="f0003">FIG. 5</figref>, the tips of the staple legs 406_L can comprise sharp tips which can incise and penetrate tissue.

0035The staples 406 can be deployed between an unfired position and a fired position such that the legs 406_L move through the staple cavities 404, penetrate tissue positioned between an anvil, like anvil 102 in <figref idref="f0001">FIG. 1</figref>, and the staple cartridge 400, and contact the anvil. As the legs 406_L are deformed against the anvil, the legs 406_L of each staple 406 can capture a portion of the tissue within each staple 406 and apply a compressive force to the tissue. Further, the legs 406_L of each staple 406 can be deformed downwardly toward the crown 406_C of the staple 406 to form a staple entrapment area in which the tissue can be captured therein. In various instances, the staple entrapment area can be defined between the inner surfaces of the deformed legs and the inner surface of the crown of the staple. The size of the entrapment area for a staple can depend on several factors such as the length of the legs, the diameter of the legs, the width of the crown, and/or the extent in which the legs are deformed, for example.

0036In use, an anvil, like anvil 102 in <figref idref="f0001">FIG. 1</figref>, can be moved into a closed position by depressing a closure trigger, like closure trigger 116 in <figref idref="f0001">FIG. 1</figref>, to advance an E-beam, like E-beam 233 in <figref idref="f0002">FIG. 3</figref>. The anvil can position tissue against a tissue-contacting surface 410 of the staple cartridge 400. Once the anvil has been suitably positioned, the staples 406 can be deployed.

0037To deploy staples 406, as discussed above, a staple-firing sled, like sled 230 in <figref idref="f0002">FIG. 2</figref>, can be moved from a proximal end 400p toward a distal end 400d of the staple cartridge 400. As a firing assembly, like firing assembly 228 in <figref idref="f0002">FIG. 3</figref>, is advanced, the sled can contact the staple drivers 408 and lift the staple drivers 408 upwardly within the staple cavities 404. In at least one example, the sled and the staple drivers 408 can each include one or more ramps, or inclined surfaces, which can co-operate to move the staple drivers 408 upwardly from their unfired positions. As the staple drivers 408 are lifted upwardly within their respective staple cavities 404, the staple drivers 408 can lift the staples 406 upwardly such that the staples 406 can emerge from their staple cavities 404 and penetrate into tissue. In various instances, the sled can move several staples upwardly at the same time as part of a firing sequence.

0038A person skilled in the art will appreciate that, while scaffolds are shown and described below, the scaffolds disclosed herein can be used with other surgical instruments, and need not be coupled to a staple cartridge as described.

0039As discussed above, with some surgical staplers, a surgeon is often required to select the appropriate staples having the appropriate staple height for the tissue that is to be stapled. For example, a surgeon could select tall staples for use with thick tissue and short staples for use with thin tissue. In some instances, however, the tissue being stapled does not have a consistent thickness and, thus, the staples cannot achieve the desired fired configuration for every section of the stapled tissue (e.g., thick and thin tissue sections). The inconsistent thickness of tissue can also lead to undesirable leakage and/or tearing of tissue at the staple site when staples with the same or substantially the same height are used, particularly when the staple site is exposed to intra-tissue pressures at the staple site and/or along the staple line.

0040Accordingly, various embodiments of scaffolds are provided that can be configured to compensate for varying thickness of tissue that is captured within fired (deployed) staples to avoid the need to take into account staple height when stapling tissue during surgery. That is, the scaffolds described herein can allow a set of staples with the same or similar heights to be used in stapling tissue of varying thickness (i.e., from thin to thick tissue) while also, in combination with the scaffold, provide adequate tissue compression within and between fired staples. Thus, the scaffolds described herein can maintain suitable compression against thin or thick tissue stapled thereto to thereby minimize leakage and/or tearing of tissue at the staple sites.

0041Alternatively or in addition, the scaffold can be configured to promote tissue ingrowth. In various instances, it is desirable to promote the ingrowth of tissue into an implantable scaffold, to promote the healing of the treated tissue (e.g. stapled and/or incised tissue) and/or to accelerate the patient's recovery. More specifically, the ingrowth of tissue into an implantable scaffold may reduce the incidence, extent, and/or duration of inflammation at the surgical site. Tissue ingrowth into and/or around the implantable scaffold may manage the spread of infections at the surgical site, for example. The ingrowth of blood vessels, especially white blood cells, for example, into and/or around the implantable scaffold may fight infections in and/or around the implantable scaffold and the adjacent tissue. Tissue ingrowth may also encourage the acceptance of foreign matter (e.g., the implantable scaffold and the staples) by the patient's body and may reduce the likelihood of the patient's body rejecting the foreign matter. Rejection of foreign matter may cause infection and/or inflammation at the surgical site.

0042In general, the scaffolds provided herein are designed and positioned atop a staple cartridge, like staple cartridge 400 in <figref idref="f0003">FIG. 4</figref>, such that when the staples are fired (deployed) from the cartridge deck of the staple cartridge, the staples penetrate through the scaffold and into tissue. As the legs of the staple are deformed against the anvil that is positioned opposite the staple cartridge assembly, the deformed legs capture a portion of the scaffold and a portion of the tissue within each staple. That is, when the staple is fired into tissue, at least a portion of the scaffold becomes positioned between the tissue and the fired staple. While the scaffolds described herein are configured to be attached to a staple cartridge of a staple cartridge assembly, it is also contemplated herein that the scaffolds can be configured to mate with other instrument components, such as a jaw of a surgical stapler.

0043<figref idref="f0004">FIG. 6</figref> illustrates an exemplary embodiment of a staple cartridge assembly 600 that includes a staple cartridge 602 and a scaffold 604. Aside from the differences described in detail below, the staple cartridge 602 can be similar to staple cartridge 400 (<figref idref="f0003">FIG. 4</figref>) and is therefore not described in detail herein. As shown, the scaffold 604 is positioned against the staple cartridge 602. The staple cartridge can include a cartridge deck 606 and a plurality of staples 608, like staples 406 shown in <figref idref="f0003">FIGS. 4 and 5</figref>. The staples 608 can be any suitable unformed (pre-deployed) height. For example, the staples 608 can have an unformed height between about 2 mm to 4.8 mm. Prior to deployment, the crowns of the staples 608 can be supported by staple drivers 610.

0044In the illustrated embodiment, the scaffold 604 can be mated to an outer surface 612, for example a tissue-contacting surface, of the cartridge deck 606. The outer surface 612 of the cartridge deck 606 can include one or more attachment features. The one or more attachment features can be configured to engage the scaffold 604 to avoid undesirable movements of the scaffold 604 relative to the cartridge deck 606 and/or premature release of the scaffold 604 from the cartridge deck 606. Exemplary attachment features can be found in <patcit id="pcit0005" dnum="US20160106427A"><text>U.S. Patent Publication No. 2016/0106427</text></patcit>.

0045The scaffold 604 is elastically deformable to permit the scaffold to compress to varying heights to thereby compensate for different tissue thickness that are captured within a deployed staple. The scaffold 604 has an uncompressed (undeformed), or pre-deployed, height and is configured to deform to one of a plurality of compressed (deformed), or deployed, heights. For example, the scaffold 604 can have an uncompressed height which is greater than the fired height of the staples 608 (e.g., the height (H) of the fired staple 608a in <figref idref="f0005">FIG. 7</figref>). In one embodiment, the uncompressed height of the scaffold 604 can be about 10% taller, about 20% taller, about 30% taller, about 40% taller, about 50% taller, about 60% taller, about 70% taller, about 80% taller, about 90% taller, or about 100% taller than the fired height of the staples 608. In certain embodiments, the uncompressed height of the scaffold 604 can be over 100% taller than the fired height of the staples 608, for example.

0046The scaffold 604 can be releasably mated to the outer surface 612 of the cartridge deck 606. As shown in <figref idref="f0005">FIG. 7</figref>, when a staple is fired, tissue (T) and a portion of the scaffold 604 is captured by the fired (formed) staple 608a. The fired staple 608a defines the entrapment area therein, as discussed above, for accommodating the captured scaffold 604 and tissue (T). The entrapment area defined by the fired staple 608a is limited, at least in part, by a height (H) of the fired staple 608a. For example, the height of a fired staple 608a can be about 3.30 mm (0.130 inches) or less. In some embodiments, the height of a fired staple 608a can be from about 0.025 inches to 3.30 mm (0.130 inches). In some embodiments, the height of a fired staple 608a can be from about 0.76 mm (0.030 inches) to 2.54 mm (0.100 inches).

0047As described above, the scaffold 604 can be compressed within a plurality of fired staples whether the thickness of the tissue captured within the staples is the same or different within each staple. In at least one exemplary embodiment, the staples within a staple line, or row, can be deformed such that the fired height is about 2.75 mm, for example, where the tissue (T) and the scaffold 604 can be compressed within this height. In certain instances, the tissue (T) can have a compressed height of about 1.0 mm and the scaffold 604 can have a compressed height of about 1.75 mm. In certain instances, the tissue (T) can have a compressed height of about 1.50 mm and the scaffold 604 can have a compressed height of about 1.25 mm. In certain instances, the tissue (T) can have a compressed height of about 1.75 mm and the scaffold 604 can have a compressed height of about 1.00 mm. In certain instances, the tissue (T) can have a compressed height of about 2.00 mm and the scaffold 604 can have a compressed height of about 0.75 mm. In certain instances, the tissue (T) can have a compressed height of about 2.25 mm and the scaffold 604 can have a compressed height of about 0.50 mm. Accordingly, the sum of the compressed heights of the captured tissue (T) and scaffold 604 can be equal, or at least substantially equal, to the height (H) of the fired staple 608a.

0048As discussed in more detail below, the structure of the scaffold can be configured such that when the scaffold and tissue are captured within the fired staple, the scaffold can apply a stress that can withstand the pressure of circulating blood through tissue. High blood pressure is typically considered 210 mmHg, and therefore it would be desirable for the scaffold to apply a stress to the tissue that is equal to or greater than 210 mmHg (e.g., 29000 N/m² (3 gf/mm²)) for a predetermined time period (e.g., 3 days). As such, in certain embodiments, the scaffold can be configured to apply a stress of at least about 29000 N/m² (3 gf/mm²) to the captured tissue for at least 3 days. The scaffold is in a tissue deployed state when the scaffold is stapled to tissue <i>in vivo.</i> In one embodiment, the applied stress can be about 29000 N/m² (3 gf/mm²). In another embodiment, the applied stress can be greater than 29000 N/m² (3 gf/mm²). In yet another embodiment, the stress can be at least about 29000 N/m² (3 gf/mm²) and applied to the captured tissue for more than 3 days. For example, in one embodiment, the stress can be at least about 29000 N/m² (3 gf/mm²) and applied to captured tissue for about 3 days to 5 days.

0049In order to design a scaffold that is configured to apply a stress of at least about 3 g/mm² to the captured tissue for a predetermined time, one can use the principles of Hooke's law (F=kD). For example, when the force (stress) to be applied to the captured tissue is known, one can design a scaffold to have a stiffness (k). The stiffness can be set by tuning the materials and/or the geometry of the scaffold (e.g., the type and/or diameter of the fibers and/or the interconnectivity of the fibers). Further, one can design the scaffold to have a maximum amount of compression displacement for a minimum thickness of tissue, e.g., 1 mm, and therefore the length of displacement D can be the combination of a minimum thickness of tissue, e.g., 1 mm, plus a thickness of the tissue when stapled to tissue for a given max staple height, e.g., 2.75 mm. By way of example, in one embodiment, a scaffold can be structured to have a height that is greater than a maximum formed stapled height of 2.75 mm and to compress to a height of 1.75 mm when stapled to tissue having a minimum thickness of 1 mm. Therefore, the scaffold can vary in compressibility to maintain a constant length of displacement D such that the stiffness (k) and total thickness (D) of captured tissue and scaffold can apply a stress of 29000 N/m² (3 gf/mm²) to the captured tissue. It should be noted a person of ordinary skill in the art will appreciate that the foregoing formula can be modified to take into account variations in temperatures, e.g., when the adjunct is brought from room temperature to body temperature after implantation.

0050Additionally, the scaffold can be further developed to provide a substantially continuous stress to the captured tissue (e.g., 29000 N/m² (3 gf/mm²)) for a predetermined time (e.g., 3 days). To achieve this, one would need to take into account the degradation rate of the materials of the scaffold and the rate of tissue ingrowth within the scaffold when designing the scaffold. In doing so, one can design a scaffold such that the stiffness of the scaffold and/or the total thickness of the captured tissue and scaffold do not vary in a way that could effect an applied stress that is less than 29000 N/m² (3 gf/mm²).

0051A scaffold is stapled to tissue under various stapling conditions (e.g., tissue thickness, height of formed staple, intra-tissue pressure). Depending on the stapling condition, one can determine an effective amount of stress that the scaffold needs to be able to apply to the tissue to prevent tissue tearing and leakage. For example, in one embodiment, an effective amount of stress is at least about 29000 N/m² (3 gf/mm²). In order for the scaffold to provide an effective amount of stress to the tissue, the scaffold can be designed to effectively compensate for the various stapling conditions. As such, the scaffold can be tailored to assume different compressed heights when stapled to tissue. As there is a finite range of intra-tissue pressures, tissue thicknesses, and formed staple heights, one can determine appropriate material and/or geometric structures for the scaffold that can be effective in applying a substantially continuous desired stress to the tissue (e.g., 29000 N/m² (3 gf/mm²)) when stapled thereto for a given amount of time (e.g., at least 3 days) over a range of stapling conditions. That is, as described in more detail below, the present scaffolds are formed of compressible materials and geometrically configured so as to allow the scaffold to compress to various heights in predetermined planes when stapled to tissue. Further, this varied response by the scaffold can also allow the scaffold to maintain its application of a continuous desired stress to the tissue when exposed to fluctuations in intra-tissue pressure that can occur when the scaffold is stapled to tissue (e.g., a spike in blood pressure).

0052The scaffold can have a variety of configurations. For example, in certain embodiments, the scaffold can include at least one knitted layer and at least one support layer. As used herein, "knitted layer" is used synonymously with "knitted zone," and "support layer" is used synonymously with "spacer zone."

0053<figref idref="f0006 f0007">FIGS. 8A-8C</figref> and <figref idref="f0008">9</figref> illustrate an exemplary embodiment of a scaffold 800 having first and second knitted layers 802, 804 with a support layer 806 disposed therebetween. In this illustrated embodiment, the first knitted layer 802 can be configured to be positioned against tissue and the second knitted layer 804 can be configured to be positioned against a cartridge deck, like cartridge deck 606 in <figref idref="f0004">FIG. 6</figref>.

0054As shown, the knitted layers 802, 804 includes fibers 808 of a first type and fibers 810 of a second type, and the support layer 806 includes the second type of fibers 810. In this way, by having the scaffold 800 formed of two different fibers 808, 810 the scaffold can have a variable stiffness profile over time following implantation. For example, the first type of fibers 808 can function as a structural component of the knitted layers 802, 804, and the stiffness profile can be a function of the degradation profile of the first type of fibers 808 and the interaction between the first type of fibers 808 with the second type of fibers 810 in the knitted layers 802, 804.

0055Further, the knitted layers 802, 804 can be configured such that when the scaffold 800 is attached to a cartridge deck, at least a portion of the first type of fibers 808 are oriented in a direction that is substantially parallel to the cartridge deck. While the first and second type of fibers 808, 810 can have a variety of sizes, in some implementations, the first type of fibers 808 has a fiber diameter that is less than a fiber diameter of the second type of fibers 810.

0056While the fibers 808, 810 of the knitted layers 802, 804 and of the support layer 806 can either be monofilament or multifilament, in some implementations, the first type of fibers 808 are multifilament fibers and the second type of fibers 810 are monofilament fibers, as shown in <figref idref="f0006 f0007">FIGS. 8A-8C</figref> and <figref idref="f0008">9</figref>. As used herein, the term "monofilament fibers" has its own ordinary and customary meaning and can include fibers formed of a single filament. As used herein, the term "multifilament fibers" has its own ordinary and customary meaning and can include fibers formed of two or more filaments that are associated with one another to form a unitary structure. In one embodiment, the multifilament fibers are non-bonded multifilament fibers. As used herein, a "non-bonded multifilament fiber" has its own ordinary and customary meaning and can include an assembly of two or more filaments that are in contact with one another at least one point along their lengths but are not physically attached to one another. Non-limiting examples of non-bonded multifilament fibers include yarn (filaments twisted about one another along their lengths) and tow (filaments not twisted about one another along their lengths).

0057The multifilament fibers can have a variety of configurations. For example, in some implementations, each multifilament fiber includes from about 6 to 40 filaments. In one aspect, each multifilament fiber includes from about 14 to 28 filaments. The increased surface area and voids that exist between the filaments of the multifilament fibers can facilitate improved tissue ingrowth within the scaffold (see e.g., Example 2).

0058The multifilament fibers can have a variety of sizes. For example, each multifilament fiber can have an average diameter of about 0.02 mm to 0.2 mm, of about 0.05 mm to 0.2 mm, or of about 0.15 mm to 0.2 mm. In some implementations, each filament of the multifilament fibers has a diameter that is less than a fiber diameter of the monofilament fibers. For example, where the knitted layers 802, 804 include first type of fibers that are multifilament fibers and second type of fibers that are monofilament fibers, each filament of the multifilament fibers can have a diameter that is about 1/5 to 1/20 the diameter of the monofilament fibers. In certain embodiments, each filament of the multifilament fibers can have a diameter that is about 1/10 the diameter of the monofilament fibers.

0059The multifilament fibers can be formed of filaments formed of the same material or filaments of different materials. For example, in some implementations, the multifilament fibers can include first filaments of a first material and second filaments of a second material. In one embodiment, the second material degrades at a faster rate than a degradation rate of the first material. In this way, the degradation of the second material can activate, and thus encourage accelerated attraction of, macrophages and accelerate the inflammation phase of healing while not substantially affecting the variable stiffness profile of the scaffold over time following implantation. The activation of macrophages can in turn cause increases in myofibroblast population and neovascularization. Further, the degradation of the second material can encourage tissue ingrowth within the scaffold. The first material, for example, can be at least one of poly-L-lactic acid, a copolymer of glycolide and L-lactide, a copolymer of glycolic acid and lactic acid, poly(lactic-co-glycolic acid), poly(lactic acid), polyglycolide, and a copolymer of glycolide, caprolactone, trimethylene carbonate, and lactide. Non-limiting examples of suitable first materials can be formed of polyglactin 910, Lactomer^™ 9-1, 75:25 or 50:50 lactic acid/glycolic acid, Polygytone^™ 6211, or Caprosyn^™. The second material, for example, can be a copolymer of glycolide and L-lactide, such as Vicryl Rapide^™.

0060While the multifilament fibers can include the second filaments at various percentage ranges, in some implementations, the multifilament fibers can each include second filaments at a range of about 15% to 85% or at a range of about 25% to 45%. The second filaments can have various fiber diameters. For example, in some implementations, the second filaments can have a fiber diameter from about 0.0005 mm to 0.02 mm. In one embodiment, the second filaments have a fiber diameter of about 0.015 mm.

0061The monofilament fibers can have a variety of sizes. For example, the monofilaments can have a diameter of about 0.2 mm to 0.35 mm. In some implementations, the monofilament fibers can each have a diameter that is less than an average diameter of the multifilament fibers. The average diameter (D) of a multifilament fiber can be calculated using the following formula: <maths id="math0001" num=""><math display="block"><mi>D</mi><mo>=</mo><msqrt><mfrac><mrow><mn>4</mn><mi>W</mi></mrow><mi mathvariant="italic">Nρπ</mi></mfrac></msqrt></math><img file="EP3530203B1_D0001.tif" /></maths> where, <ul id="ul0002" list-style="none" compact="compact"><li>W = weight of multifilament fiber (fiber bundle) per unit length</li><li>N = number of filaments</li><li>ρ = density of fiber.</li></ul>

0062While the first and second type of fibers 808, 810 can have various glass transition temperatures, in some implementations, the first type of fibers 808 have a first glass transition temperature and the second type of fibers 810 have a second glass transition temperature that is less than the first glass transition temperature. For example, the first glass transition temperature can be greater than the second glass transition temperature by at least about 30 degrees C. In other exemplary embodiments, the first glass transition temperature can be greater than the second glass transition temperature by at least about 45 degrees C. A difference in glass transition of the first and second types of fibers 808, 810 can further facilitate a secure attachment of the scaffold to the cartridge deck without adversely affecting the structural integrity of the scaffold.

0063As discussed above, a portion of the scaffold is captured with tissue within the fired staple and therefore it is desirable that the scaffold be formed of suitable bioabsorbable materials. As such, the first and second type of fibers 808, 810 can each be formed of a variety of absorbable materials. Non-limiting examples of suitable materials for the first type of fibers include at least one of poly-L-lactic acid, a copolymer of glycolide and L-lactide, a copolymer of glycolic acid and lactic acid, poly(lactic-co-glycolic acid), poly(lactic acid), polyglycolide, and a copolymer of glycolide, caprolactone, trimethylene carbonate, and lactide. For example, the first type of fibers can be formed of polyglactin 910, Lactomer^™ 9-1, 75:25 or 50:50 lactic acid/glycolic acid, Polygytone^™ 6211, or Caprosyn^™. Non-limiting examples of suitable materials for the second type of fibers include at least one of polydioxanone, a copolymer of polydioxanone and polyglycolide, a copolymer of lactide and polycaprolactone), a copolymer of glycolide, dioxanone, and trimethylene carbonate, poly(trimethylene carbonate), polyhydroxyalkanoate, and polyglyconate. For example, the second type of fibers can be formed of 92:8 polydioxanone/Polyglycolide, 25:75 lactide/polycaprolactone, Glycomer^™631, or Maxon^™. In one embodiment, the first type of fibers is formed of polyglactin 910 and the second type of fibers is formed of polydioxanone.

0064In some embodiments, the first type of fibers 808 can be coated with a bioabsorbable polymeric material. In this way, the glass transition temperature of the first type of fibers 808 can be modified, e.g., by either increasing or decreasing the glass transition compared to the glass transition temperature of the base material of the first type of fibers, which in certain instances may be desirable for attaching the scaffold to the cartridge deck. For example, decreasing the glass transition temperature of the first type of fibers 808 can provide a more secure attachment of the scaffold 800 to a cartridge deck, like cartridge deck 606 in <figref idref="f0004">FIG. 6</figref>, and/or enhance the conformability of the scaffold 800 to the cartridge deck and, when cooled, maintain a suitable shape. Non-limiting examples of suitable coating materials include polydioxanone or 25:75 lactide/polycaprolactone.

0065While the knitted layers 802, 804 can each have various knitted patterns, in some implementations, like in <figref idref="f0006 f0007">FIGS. 8A-8C</figref> and <figref idref="f0008">9</figref>, the knitted layers 802, 804 can each have a Raschel knit pattern (e.g., as described in Example 1 below). A person skilled in the art will appreciate that the knitted layers of the scaffold can take the form of other warp knitted patterns.

0066As shown in <figref idref="f0006 f0007">FIGS. 8A-8C</figref> and <figref idref="f0008">9</figref>, the second type of fibers 810 interconnect with the first type of fibers 808 of the first and second knitted layers 802, 804 in a manner in which the first and second fibers are non-fixedly attached and slidably interconnected. As such, in this illustrated embodiment, the first and second type of fibers 808, 810 can move relative to each other, thereby allowing for movement and for expansion in the x-direction (e.g., stretch) and the y-direction (e.g., compression). Additionally, the interconnection between the first and second type of fibers 808, 810 can affect, at least in part, the stiffness of the scaffold 800. For example, the tighter the interconnection, the stiffer the scaffold 800.

0067Further, as shown in the <figref idref="f0006 f0007">FIGS. 8A-8C</figref> and <figref idref="f0008">9</figref>, the first and second knitted layers 802, 804 each include a plurality of openings 812 formed therein. The openings 812 of the first and second knitted layers 802, 804 each have a perimeter formed of the first and second types of fibers 808, 810. The openings 812 of the second knitted layer 804 can have a size that is less than about ¼ of a width of a crown of a staple, like staple 406 in <figref idref="f0003">FIG. 5</figref>. As such, in some implementations, the crown of the fired staple can span over at least four openings 812 in the second knitted layer 804. In one embodiment, the openings 812 can have a size that is about 1/8 of the width of the crown. While the crown of a staple can have a variety of widths, in some implementations, the width of the crown can be about 2.03 mm (0.080 inches) to 3.56 mm (0.140 inches). In one embodiment, the width of the crown is about 3.5 mm (0.12 inches).

0068The plurality of openings 812 in the first and second knitted layers 802, 804 can have a variety of sizes. For example, the plurality of openings 812 in the second knitted layer 804 can have a diameter from about 0.05 mm (0.002 inches) to 2.5 mm (0.1 inches). As used herein, "diameter" of an opening is the largest distance between any pair of vertices of the opening.

0069As discussed above and shown in <figref idref="f0006 f0007">FIGS. 8A-8C</figref> and <figref idref="f0008">9</figref>, the scaffold 800 includes a support layer 806 that is positioned between the first and second knitted layers 802, 804. The support layer 806 is non-fixedly attached to first and second knitted layers 802, 804. The support layer 806 can be configured such that when the scaffold 800 is attached to a cartridge deck, like cartridge deck 606 in <figref idref="f0004">FIG. 6</figref>, at least a portion of the second type of fibers 810 of the support layer 806 are oriented in a direction that is substantially non-parallel to the cartridge deck. While the support layer 806 is shown in <figref idref="f0006 f0007">FIGS. 8A-8C</figref> and <figref idref="f0008">9</figref>, to include only the second type of fibers 810, which in this exemplary embodiment, are monofilaments, it is also contemplated herein that the support layer 806 can include additional types of fibers, including, for example, the first type of fibers 808.

0070As shown, the fibers 810 of the support layer 806 are arranged within the support layer 806 to form standing (spacer) fibers 814 and a plurality of voids 816 therebetween. The standing fibers 814 are non-fixedly attached to each other. Further, the standing fibers 814 are non-fixedly and slidably interconnected to the first type of fibers 808 of the first and second knitted layers 802, 804. In some implementations, the plurality of voids 816 can be larger than the plurality of openings 812 in the first and second knitted layers 802, 804.

0071The standing fibers 814 are configured to bend under force applied to the scaffold 800 (e.g., when stapled to tissue). The resilience of the standing fibers 814 permits, at least in part, the scaffold to compress at various heights to thereby accommodate tissue (T) with tissue portions of different thicknesses. That is, independent of the particular tissue thickness, the sum of the compressed heights of the captured tissue and scaffold within the fired staple can be maintained, and thus can remain equal, or at least substantially equal, to the height of the fired staple. In this way, at least in part, the scaffold 800 can be configured to apply a stress of at least about 29000 N/m² (3 gf/mm²) to the captured tissue for at least a predetermined period (e.g., at least about 3 days).

0072Generally, the material composition, the height, and/or the transverse cross-sectional area of each standing fiber 814 controls, at least in part, its stiffness or ability to bend under compression which, in turn, controls, at least in part, the compressibility of the scaffold 800. Accordingly, the standing fibers 814 can be configured to tune the compressibility of the scaffold 800 to one or more desired values. For example, while the standing fibers 814 in <figref idref="f0007">FIGS. 8B-8C</figref> and <figref idref="f0008">9</figref> are of the same material, in some implementations, the support layer 806 can include standing fibers of different materials with different stiffnesses. Alternatively or in addition, in some implementations, the support layer 806 can include standing fibers of different heights and/or transverse cross-sectional areas. In one embodiment, the standing fibers 814 can have a high length-to-diameter ratio, for example, a ratio of about 25:1 to 6:1. In this way, the standing fibers 814 can further encourage tissue ingrowth and cell integration within the implanted scaffold.

0073The amount of the standing fibers 814 within a certain section of the support layer 806 can also affect, among other things, the compressibility of such section, and thus the compressibility of the scaffold 800. In certain instances, the standing fibers 814 can be strategically concentrated in certain sections of the support layer 806 to provide greater column strength in such sections, for example. In at least one instance, the standing fibers 814 can be concentrated in sections of the support layer 806 that are configured to receive staples when the staples are fired. Alternatively, the standing fibers 814 can be concentrated in sections of the support layer 806 that do not receive staples when the staples are fired.

0074The ratio of the voids 816 to the standing fibers 814 can vary. In one implementation this ratio can be in the range of at least about 3:1. In other implementations, the ratio of voids 816 to the standing fibers 814 can in the range of at least about 5:1 or of at least about 12:1. Further, at least a portion of the voids 816 in the support layer 806 can each have a different size. In this way, the variable void sizes throughout the cross-section of the scaffold 800 can promote extracellular remodeling. That is, the variable void sizes can facilitate revascularization as well as mobility of cells within the scaffold 800 when the scaffold is implanted, thereby encouraging both tissue and cellular ingrowth. Further the variable void sizes can also facilitate extraction of byproducts and cellular waste from the implanted scaffold, and thus the implantation site.

0075In some embodiments, the scaffold 800 can also include a porous layer interconnected to the second knitted layer 804. In this way, when the scaffold 800 is attached to a cartridge deck, like cartridge deck 606 in <figref idref="f0004">FIG. 6</figref>, the porous layer would be positioned between the cartridge deck and the second knitted layer 804. In one embodiment, the porous layer is fused or bonded to the second knitted layer 804. The porous layer can be formed of a material having a lower glass transition temperature than the fibers 808, 810 of the scaffold 800. It is also contemplated herein that the porous layer can be formed of a material having the same or a higher glass transition temperature than at least one of the fibers 808, 810 of the scaffold 800. The porous layer can have a thickness that is less than about 0.08 mm (0.003 inches). In one embodiment, the porous layer has a thickness that is less than about 0.025 mm (0.001 inches). The porous layer can also include pores that are greater than about 0.013 mm (0.0005 inches) in diameter. For example, in some implementations, the pores can vary in size from about 0.013 mm (0.0005 inches) to about 0.025 mm (0.001 inches). Further, in some implementations, the pores can make up at 50% of the surface area of the layer.

0076The scaffolds described herein, like scaffold 800 in <figref idref="f0006 f0007">FIGS. 8A-8C</figref> and <figref idref="f0008">9</figref>, can be manufactured using any suitable methods. For example, in one embodiment, the method can include forming a first knitted layer, forming a second knitted layer, and interknitting spacers with the first and second knitted layers. The first and second knitted fibers can comprise fibers of a first polymer. The first knitted layer can be configured to mate with a cartridge deck. Interknitting the spacer fibers with the first and second knitted layers can connect the first and second knitted layers together in a spaced parallel relation. As used herein, a "spaced parallel relation" means that the first and second layers extend within planes that are distanced from and substantially parallel with one another. The spacer fibers can be formed of only a second polymer that is different than the first polymer. The first polymer fibers can have a diameter that is different than a diameter of the second polymer fibers. The spacer fibers can be integrated with and extending between the first and second knitted layers. The method can also include annealing the first and second knitted layers interknitted with the spacer fibers.

0077The interknitting of the spacer fibers with the first and second knitted layers can form a support layer therebetween. The formation of the first knitted layer can include knitting the first polymer fibers according to a predetermined pattern. The formation of the second knitted layer can include knitting the first polymer fibers according to a predetermined pattern. While the knitted layers can each have various knitted patterns, in some implementations, the knitted layers can each have a Rachel knit pattern (e.g., as described in Example 1 below). A person skilled in the art will appreciate that the knitted layers of the scaffold can take the form of other warp knitted patterns.

0078<figref idref="f0010">FIG. 12A</figref> illustrates another exemplary embodiment of a scaffold 1000. Aside from the differences described in detail below, the scaffold 1000 can be similar in construction to the scaffold 800 (<figref idref="f0006 f0007">FIGS. 8A-8C</figref> and <figref idref="f0008">9</figref>) and is therefore not described in detail herein. In this embodiment, the scaffold 1000 includes a first knitted layer 1002 having a first portion 1004 and a second portion 1006, each having outer and inner edges. The inner edges 1004a, 1006a define a channel 1008 that extends along the longitudinal axis (L) of the scaffold 1000. The channel 1008 is configured to receive a cutting member, such as a knife. As shown in <figref idref="f0011">FIG. 12B</figref>, the channel 1008 does not extend completely through the scaffold 1000. In particular, the channel 1008 does not extend through the second knitted layer 1010. In this way, the scaffold 1000 is configured to have sufficient structural integrity to thereby be effectively manipulated and attached to a cartridge deck, like cartridge deck 2014 in <figref idref="f0011">FIG. 12B</figref>. In another embodiment, as shown in <figref idref="f0012">FIG. 13</figref>, the scaffold 3000 can have a channel 3008 that is perforated. In use, when the cutting member is initially fired and travels along the scaffold 1000, the cutting member cuts through the second knitted layer 1010, thereby separating the scaffold 1000 into two pieces.

0079Further, as shown in <figref idref="f0010">FIG. 12A</figref>, the scaffold 1000 includes flanges 1012 that are configured to mate with recessed channels, like recessed channels 2016 of cartridge deck 2014 in <figref idref="f0011">FIG. 12B</figref>, as further described below. While <figref idref="f0010">FIG. 12A</figref> illustrates the scaffold 1000 having flanges 1012 at one side of the scaffold 1000, there are additional flanges 1012 positioned at the opposite side of the scaffold 1000. A person skilled in the art will appreciate that the number and placement of flanges 1012 are not limited to what is shown in <figref idref="f0010">FIG. 12A</figref>. While the flanges 1012 can be made of a variety of materials, in some implementations, as shown in <figref idref="f0010">FIG. 12A</figref>, the flanges 1012 are an extension of the second knitted layer 1010. In other embodiment, the flanges 1012 can be formed of different material and formed in-line or offline with the other components of the scaffold 1000. A person skilled in the art will appreciate that the flanges can be formed of the same or different materials than that of the first and/or second knitted layers of the scaffold and can be attached thereto by any suitable method.

0080<figref idref="f0011">FIG. 12B</figref> illustrates another exemplary embodiment of a staple cartridge assembly 2000. Aside from the differences described in detail below, the staple cartridge assembly 2000 can be similar to staple cartridge assembly 600 (<figref idref="f0004">FIG. 6</figref>) and is therefore not described in detail herein. Further, for purposes of simplicity, certain components of the staple cartridge assembly 2000 are not illustrated in <figref idref="f0011">FIG. 12B</figref>.

0081The staple cartridge assembly 2000 includes the scaffold 1000 in <figref idref="f0010">FIG. 12A</figref> attached to a cartridge deck 2014 having recessed channels 2016. The scaffold 1000 can be attached to the cartridge deck using any suitable methods, as described in more detail below. As shown, the recessed channels 2016 are configured to receive the flanges 1012 such that the flanges 1012 can attach to the side(s) of the cartridge deck. In this way, the scaffold 1000 can be more securely attached to the cartridge deck 2014, thereby preventing undesired movement of the scaffold 1000 during use.

0082The scaffolds can be applied to a cartridge deck to form a staple cartridge assembly using any suitable method. For example, in some embodiments, the method can include heating a cartridge deck and positioning a scaffold against a surface of the cartridge deck. The scaffold can include first and second type of fibers in which the first type of fibers are predominately present. As used herein, "predominately present" when used to describe the amount of particular fibers in a layer means an amount that is greater than 50% of the total amount fibers within that layer. The first type of fibers can have a first glass transition temperature and the second type of fibers can have a second glass transition temperature that is less than the first glass transition temperature. The cartridge deck can be heated to a temperature of at least the second glass transitions temperature. The method can also include cooling the cartridge deck and scaffold applied thereto to a temperature that is less than the second glass transition temperature.

0083The scaffold can include first and second knitted layers each having the first and second types of fibers and a support layer disposed between the first and second knitted layers. In such instance, the positioning of the scaffold against the surface of the cartridge deck can include placing the first knitted layer against the surface and applying force to the scaffold such that the first knitted layer bonds and conforms to a shape of the surface. The support layer can be formed of the second type of fibers.

0084The instruments disclosed herein can be designed to be disposed of after a single use, or they can be designed to be used multiple times. In either case, however, the instrument can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the instrument, followed by cleaning or replacement of particular pieces and subsequent reassembly. In particular, the instrument can be disassembled, and any number of the particular pieces or parts of the instrument can be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, the instrument can be reassembled for subsequent use either at a reconditioning facility, or by a surgical team immediately prior to a surgical procedure. Those skilled in the art will appreciate that reconditioning of an instrument can utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned instrument, are all within the scope of the present application.

0085The present teachings may be further understood with reference to the following non-limiting examples.

<u>EXAMPLES</u>

Example 1: Manufacturing of a Scaffold

0086A sample having two knitted layers and a support layer positioned therebetween was prepared. The two knitted layers were each formed of Vicryl fibers (multifilament fibers of Vicryl) and the support layer was formed of Polydioxanone (PDS) fibers (monofilament fibers of PDS), details of which are provided in Table 1 below. <tables id="tabl0001" num="0001"><table frame="all"><title>Table 1. Vicryl and Polydioxanone Fiber Information</title><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="45mm" align="center" /><colspec colnum="2" colname="col2" colwidth="34mm" align="center" /><colspec colnum="3" colname="col3" colwidth="16mm" align="center" /><colspec colnum="4" colname="col4" colwidth="25mm" align="center" /><thead valign="top"><row><entry>Fiber</entry><entry>Fiber Diameter (mils)</entry><entry>Ten (lbf)</entry><entry>Elongation (%)</entry></row></thead><tbody><row><entry>7-0 PDS, dyed</entry><entry>3.18</entry><entry>0.67</entry><entry>38.28</entry></row><row><entry>2 ply, 28 denier Vicryl, natural</entry><entry>1.17</entry><entry>0.58</entry><entry>20.34</entry></row></tbody></tgroup></table></tables>

0087The sample was warp knit using a 16 gauge double needle bar Raschel knitting machine with a six guide bar (GB) construction. Each guide bar was individually controlled using a pattern chain, the patterns for which can be found in Table 2 below. PDS was used in the support layer and Vicryl was used for the knitted layers. <tables id="tabl0002" num="0002"><table frame="all"><title>Table 2. Pattern Chain</title><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="21mm" /><colspec colnum="2" colname="col2" colwidth="52mm" /><colspec colnum="3" colname="col3" colwidth="27mm" /><colspec colnum="4" colname="col4" colwidth="21mm" /><thead valign="middle"><row><entry align="center">Guide Bars</entry><entry align="center">Guide Bar Movement</entry><entry align="center">Threading</entry><entry align="center">Fiber Used</entry></row></thead><tbody valign="middle"><row><entry align="center">1</entry><entry align="center">1-0; 0-0/1-2; 2-2/2-3; 3-3/2-1; 1-1//</entry><entry morerows="5" align="center">Fully Threaded</entry><entry align="center">Vicryl</entry></row><row><entry align="center">2</entry><entry align="center">2-3; 3-3/2-1; 1-1/1-0; 0-0/1-2; 2-2//</entry><entry align="center">Vicryl</entry></row><row><entry align="center">3</entry><entry align="center">(1-0; 2-3) X 4//</entry><entry align="center">PDS</entry></row><row><entry align="center">4</entry><entry align="center">(2-3; 1-0) X 4//</entry><entry align="center">PDS</entry></row><row><entry align="center">5</entry><entry align="center">2-2; 2-3/3-3; 2-1/1-1; 1-0/0-0; 1-2//</entry><entry align="center">Vicryl</entry></row><row><entry align="center">6</entry><entry align="center">1-1; 1-0/0-0; 1-2/2-2; 2-3/3-3; 2-1//</entry><entry align="center">Vicryl</entry></row></tbody></tgroup></table></tables>

0088Approximately 5.8 m (6.4 yards) of 13 cm (5 inch) wide sample was produced. The sample was scoured with isopropyl alcohol. The sample was placed on a roll, sealed in a nitrogen purged foil bag, and kept under nitrogen flow until further processing.

0089An approximate 13 cm × 13 cm (5 inch × 5 inch) segment of the sample was then annealed using cycle conditions as described in Table 3. <tables id="tabl0003" num="0003"><table frame="all"><title>Table 3. Cycle Conditions</title><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="38mm" /><colspec colnum="3" colname="col3" colwidth="21mm" /><colspec colnum="4" colname="col4" colwidth="36mm" /><colspec colnum="5" colname="col5" colwidth="38mm" /><thead valign="middle"><row><entry align="center">N₂ Purge</entry><entry namest="col2" nameend="col3" align="center">Ramp Up</entry><entry align="center">Annealing</entry><entry align="center">Cool Down</entry></row><row><entry align="center">Hours / Temperature (°C)</entry><entry align="center">Minutes / Temperature (°C)</entry><entry align="center">Speed (°C/min)</entry><entry align="center">Hours / Temperature (°C)</entry><entry align="center">Minutes / Temperature (°C)</entry></row></thead><tbody valign="middle"><row><entry align="center">1 / 30</entry><entry align="center">90/85</entry><entry align="center">0.94 / 1</entry><entry align="center">6/85</entry><entry align="center">60/30</entry></row></tbody></tgroup></table></tables>

0090The annealed sample was then cut to produce approximately 5 mm × 10 mm sample scaffolds. One of the scaffold samples was examined by optical microscopy (OM) and SEM. Various OM images of the sample scaffold is shown in <figref idref="f0006 f0007">FIGS. 8A-8C</figref>, and a cross-sectional SEM image of the scaffold sample is shown in <figref idref="f0008">FIG. 9</figref>.

Example 2: Cellular Ingrowth and Limited Inflammation

0091Sample scaffolds as prepared in Example 1 were subcutaneously implanted for up to 90 days into rabbits injected with a hematoxylin and eosin stain (H&amp;E) stain. Histopathology images of an implanted scaffold removed at 60 days is illustrated in <figref idref="f0009">FIGS. 10A-10B</figref> and an implanted scaffold removed at 90 days is illustrated in <figref idref="f0009">FIGS. 11A-11B</figref>. The white ovals/circles shown in these images are fibers of the scaffold cut either perpendicular or slightly off. As shown, the black boxes illustrate some of the portions of the scaffold in which tissue ingrowth occurred during implantation. Additionally, the arrows in <figref idref="f0009">FIGS. 10B and 11B</figref> point to inflammatory areas around the fibers, which are indicative of the inflammation phase of healing.

0092One skilled in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the invention is not to be limited by what has been particularly shown and described, except as indicated by the appended claims.