SYSTEMS AND METHODS FOR CUSTOMIZING CROSSLINKING DENSITY IN BIOABSORBABLE MATERIALS

FIELD

The present invention relates generally to systems and methods for embedding medical additives into bioabsorbable materials.

BACKGROUND

Surgical 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.

Most staplers have a handle (some of which are directly user operable, others of which are operable by a user via a robotic interface) with an elongate shaft extending from the handle and having a pair of movable opposed jaws formed on an end thereof for holding and forming staples therebetween. The staples are typically contained in a staple cartridge, which can house multiple rows of staples and is often disposed in one of the two jaws for ejection of the staples to the surgical site. In use, the jaws are positioned so that the object to be stapled is disposed between the jaws, and staples are ejected and formed when the jaws are closed, and the device is actuated. Some staplers include a knife configured to travel between rows of staples in the staple cartridge to longitudinally cut and/or open the stapled tissue between the stapled rows.

SUMMARY

There is provided, in accordance with an example of the present invention, a bioabsorbable material configured to be delivered to tissue. The material includes a porous body including at least one polymer having a first zone comprising a first crosslink density and a second zone having a second crosslink density different than the first zone. At least the first and second zones form a gradient of compression strength along a portion of the porous body.

There is provided, in accordance with an example of the present invention, a method to form a bioabsorbable material. The method can include the steps of chemically reacting a polyol and an isocyanate to form a porous body and adding a polymerizable compound to at least a portion of the porous body. The polymerizable compound can have crosslinkable units. The polymerizable compound can be configured to undergo crosslinking between the crosslinking units upon exposure to a stimulation and modulate a crosslinking density in the porous body.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of one exemplary embodiment of a conventional surgical stapling and severing instrument.

FIG. 2A is a top view of a staple cartridge for use with the surgical stapling and severing instrument of FIG. 1;

FIG. 2B is a side view of the staple cartridge of FIG. 2A;

FIG. 3 is a side view of a staple in an unfired (pre-deployed) configuration that can be disposed within the staple cartridge of the surgical cartridge assembly of FIG. 2A;

FIG. 4 is a perspective view of a knife and firing bar (“E-beam”) of the surgical stapling and severing instrument of FIG. 1;

FIG. 5 is a perspective view of a wedge sled of a staple cartridge of the surgical stapling and severing instrument of FIG. 1;

FIG. 6A is a longitudinal cross-sectional view of an exemplary surgical cartridge assembly having a compressible non-fibrous adjunct attached to a top or deck surface of a staple cartridge;

FIG. 6B is a longitudinal cross-sectional view of a surgical end effector having an anvil pivotably coupled to an elongate channel and the surgical cartridge assembly of FIG. 6A disposed within and coupled to the elongate channel, showing the anvil in a closed position without any tissue between the anvil and the adjunct;

FIG. 7A is a partial-schematic illustrating the adjunct of FIGS. 6A-6B in a tissue deployed condition;

FIG. 7B is a diagram showing an enlarged portion of an exemplary adjunct with a porous structure;

FIG. 8 is a perspective view of an exemplary cartridge assembly;

FIG. 9A is a perspective view of an exemplary surgical cartridge assembly having an adjunct of bioabsorbable material attached to a top or deck surface of a staple cartridge;

FIG. 9B is a perspective view of an exemplary surgical cartridge assembly having an adjunct of bioabsorbable material attached to a top or deck surface of a staple cartridge;

FIG. 9C is a perspective view of an exemplary surgical cartridge assembly having an adjunct of bioabsorbable material attached to a top or deck surface of a staple cartridge;

FIG. 9D is a perspective view of an exemplary surgical cartridge assembly having an adjunct of bioabsorbable material attached to a top or deck surface of a staple cartridge;

FIG. 10A is a side view of an exemplary end effector having an adjunct of bioabsorbable material in a delivery configuration;

FIG. 10B is a side view of an exemplary end effector having an adjunct of bioabsorbable material after firing and release from cartridge;

FIG. 11A is a top perspective view of an exemplary adjunct after use;

FIG. 11B is a side view of an exemplary adjunct after use; and

FIG. 12 is a flow chart showing an exemplary method of forming a surgical adjunct with spatial control of mechanical properties in bioabsorbable material.

DETAILED DESCRIPTION

The following detailed description should be read with reference to the drawings, in which like elements in different drawings are identically numbered. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.

As used herein, the terms “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, “about” or “approximately” may refer to the range of values±10% of the recited value, e.g., “about 90%” may refer to the range of values from 81% to 99%.

The term “polyurethane,” as used herein, refers to a polymeric reaction product of an isocyanate and a polyol, and is not limited to those polymers which include only urethane or polyurethane linkages. It is well understood by those of ordinary skill in the art of preparing polyurethanes that the polyurethane polymers may also include linkages such as allophanate, carbodiimide, and other linkages described herein in addition to urethane linkages.

The expressions “reaction system,” “reactive formulation,” “reaction product,” and “reactive mixture” are interchangeably used herein, and all refer to a combination of reactive compounds used to make the bioabsorbable material according to the disclosure.

The term “room temperature” refers to temperatures of about 20° C., this means referring to temperatures in the range 18° C. to 25° C. Such temperatures will include, 18° C., 19° C., 20° C., 21° C., 22° C., 23° C., 24° C. and 25° C.

Unless otherwise expressed, the “weight percentage” (indicated as % wt. or wt. %) of a component in a composition refers to the weight of the component over the total weight of the composition in which it is present and is expressed as percentage.

“Glass transition temperature” and “Tg” as referred to herein refers to the temperature at which a reversible transition from a hard glass condition into a rubber-elastic condition occurs.

Surgical stapling assemblies and methods for manufacturing and using the same are provided. In general, a surgical stapling assembly can include a staple cartridge having staples disposed therein and an adjunct configured to be releasably retained on the staple cartridge. As discussed herein, the various adjuncts provided can be configured to compensate for variations in tissue properties, such as variations in tissue thickness, and/or to promote tissue ingrowth when the adjuncts are stapled to tissue. As discussed herein, an adjunct can include a bioabsorbable material, such as a foam.

An exemplary stapling 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 stapling assembly can include only some of these features and/or it can include a variety of other features known in the art. The stapling assemblies described herein are merely intended to represent certain exemplary examples. Moreover, while the adjuncts are described in connection with surgical staple cartridge assemblies, the adjuncts can be used in connection with staple reloads that are not cartridge based or any type of surgical instrument.

FIG. 1 illustrates an exemplary surgical stapling and severing device 100 suitable for use with an implantable adjunct. The illustrated surgical stapling and severing device 100 includes end effector 106 having an anvil 102 that is pivotably coupled to an elongate channel 104. As a result, the end effector 106 can move between an open position, as shown in FIG. 1, and a closed position in which the anvil 102 is positioned adjacent to the elongate channel 104 to engage tissue therebetween. The end effector 106 can be attached at its proximal end to an elongate shaft 108 forming an implement portion 110. When the end effector 106 is closed, or at least substantially closed, (e.g., the anvil 102 moves from the open position in FIG. 1 toward the elongate channel) the implement portion 110 can present a sufficiently small cross-section suitable for inserting the end effector 106 through a trocar. While the device 100 is configured to staple and sever tissue, surgical devices configured to staple but not sever tissue are also contemplated herein.

In various instances, the end effector 106 can be 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 end effector 106 about a longitudinal axis (Ls) of the elongate shaft 108 and an articulation control 115 that can articulate the end effector 106 about an articulate axis (TA) that is substantially transverse to the longitudinal axis (Ls) of the elongate shaft 108. Further controls include a closure trigger 116 which can pivot relative to a pistol grip 118 to close the end effector 106. A closure release button 120 can be 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 end effector 106, for example. Handle 112 may also take the form of an interface for connection to a surgical robot.

In some examples, a firing trigger 122, which can pivot relative to the closure trigger 116, can cause the end effector 106 to simultaneously sever and staple tissue clamped therein. The firing trigger 122 may be powered, require force from a user to engage, or some combination thereof. 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.

Additional details on the surgical stapling and severing device 100 and other surgical stapling and severing devices suitable for use with the present disclosure are described, for example, in U.S. Pat. No. 9,332,984 and in U.S. Patent Publication No. 2009/0090763, the disclosures of which are incorporated herein by reference in their entireties. Further, the surgical stapling and severing device need not include a handle, but instead can have a housing that is configured to couple to a surgical robot, for example, as described in U.S. Patent Publication No. 2019/0059889, the disclosure of which is incorporated herein by reference in its entirety.

As further shown in FIG. 1, a staple cartridge 200 can be utilized with the instrument 100. In use, the staple cartridge 200 is placed within and coupled to the elongate channel 104. While the staple cartridge 200 can have a variety of configurations, in this illustrated example, the staple cartridge 200, which is shown in more detail in FIGS. 2A-2B, has a proximal end 202a and a distal end 202b with a cartridge longitudinal axis (LC) extending therebetween. As a result, when the staple cartridge 200 is inserted into the elongate channel 104 (FIG. 1), the longitudinal axis (LC) is substantially or approximately parallel with the longitudinal axis (LS) of the elongate shaft 108. Further, the staple cartridge 200 includes a longitudinal slot 210 defined by two opposing walls 210a, 210b and configured to receive at least a portion of a firing member of a firing assembly, like firing assembly 400 in FIG. 4, as discussed further below. As shown, the longitudinal slot 210 extends from the proximal end 202a toward the distal end 202b of the staple cartridge 200. It is also contemplated herein that in other examples, the longitudinal slot 210 can be omitted.

The illustrated staple cartridge 200 includes staple cavities 212, 214 defined therein, in which each staple cavity 212, 214 is configured to removably house at least a portion of a staple (not shown). The number, shape, and position of the staple cavities can vary and can depend at least on the size and shape (e.g., mouth-like shape) of the staples to be removably disposed therein. In this illustrated example, the staple cavities are arranged in two sets of three longitudinal rows, in which the first set of staple cavities 212 is positioned on a first side of the longitudinal slot 210 and the second set of staple cavities 214 is positioned on a second side of the longitudinal slot 210. On each side of the longitudinal slot 210, and thus for each set of rows, a first longitudinal row of staple cavities 212a, 214a extends alongside the longitudinal slot 210, a second row of staple cavities 212b, 214b extends alongside the first row of staple cavities 212a, 214a, and a third row of staple cavities 212c, 214c extends alongside the second row of staple cavities 212b, 214b. Each row may be approximately parallel and the staple cavities that make up the rows may be approximately parallel in orientation with the longitudinal slot 210. As shown in FIGS. 2A, each staple cavity 212, 214 may include a maximum length SL of about 0.122 inches to about 0.124 inches and a maximum width SW of about 0.023 inches to about 0.027 inches. In addition, at least the centers of two adjacent cavities 212, 214 are spaced apart by about 0.158 inches.

The staples releasably stored in the staple cavities 212, 214 can have a variety of configurations. An exemplary staple 300 that can be releasably stored in each of the staple cavities 212, 214 is illustrated in FIG. 3 in its unfired (pre-deployed, unformed) configuration. The illustrated staple 300 includes a crown (base) 302 and two legs 304 extending from each end of the crown 302. In this example, the crown 302 extends in a linear direction and the staple legs 304 have the same unformed height. Further, prior to the staples 300 being deployed, the staple crowns 302 can be supported by staple drivers that are positioned within the staple cartridge 200 and, concurrently, the staple legs 304 can be at least partially contained within the staple cavities 212, 214. Further, the staple legs 304 can extend beyond a top surface, like top surface 206, of the staple cartridge 200 when the staples 300 are in their unfired positions. In certain instances, as shown in FIG. 3, the tips 306 of the staple legs 304 can be pointed and sharp which can incise and penetrate tissue.

In use, staples 300 can be deformed from an unfired position into a fired position such that the staple legs 304 move through the staple cavities 212, 214, penetrate tissue positioned between the anvil 102 and the staple cartridge 200, and contact the anvil 102. As the staple legs 304 are deformed against the anvil 102, the legs 304 of each staple 300 can capture a portion of the tissue within each staple 300 and apply a compressive force to the tissue. Further, the legs 304 of each staple 300 can be deformed downwardly toward the crown 302 of the staple 300 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.

In some examples, all of the staples disposed within the staple cartridge 200 can have the same unfired (pre-deployed, unformed) configuration. In other examples, the staples can include at least two groups of staples each having a different unfired (pre-deployed, unformed) configuration, e.g., varying in height and/or shape, relative to one another, etc.

Referring back to FIGS. 2A-2B, the staple cartridge 200 extends from a top surface or deck surface 206 to a bottom surface 208, in which the top surface 206 is configured as a tissue-facing surface and the bottom surface 208 is configured as a channel-facing surface. As a result, when the staple cartridge 200 is inserted into the elongate channel 104, as shown in FIG. 1, the top surface 206 faces the anvil 102 and the bottom surface 208 (obstructed) faces the elongate channel 104.

With reference to FIGS. 4 and 5, a firing assembly such as, for example, firing assembly 400, can be utilized with a surgical stapling and severing device, like device 100 in FIG. 1. The firing assembly 400 can be configured to advance a wedge sled 500 having wedges 502 configured to deploy staples from the staple cartridge 200 into tissue captured between an anvil, like anvil 102 in FIG. 1, and a staple cartridge, like staple cartridge 200 in FIG. 1. Furthermore, an E-beam 402 at a distal portion of the firing assembly 400 may fire the staples from the staple cartridge. During firing, the E-beam 402 can also cause the anvil to pivot towards the staple cartridge, and thus move the end effector from the open position towards a closed position. The illustrated E-beam 402 includes a pair of top pins 404, a pair of middle pins 406, which may follow a portion 504 of the wedge sled 500, and a bottom pin or foot 408. The E-beam 402 can also include a sharp cutting edge 410 configured to sever the captured tissue as the firing assembly 400 is advanced distally, and thus towards the distal end of the staple cartridge. In addition, integrally formed and proximally projecting top guide 412 and middle guide 414 bracketing each vertical end of the cutting edge 410 may further define a tissue staging area 416 assisting in guiding tissue to the sharp cutting edge 410 prior to being severed. The middle guide 414 may also serve to engage and fire the staples within the staple cartridge by abutting a stepped central member 506 of the wedge sled 500 that effects staple formation by the end effector 106.

In use, the anvil 102 in FIG. 1 can be moved into a closed position by depressing the closure trigger in FIG. 1 to advance the E-beam 402 in FIG. 4. The anvil 102 can position tissue against at least the top surface 206 of the staple cartridge 200 in FIGS. 2A-2B. Once the anvil has been suitably positioned, the staples 300 in FIG. 3 disposed within the staple cartridge can be deployed.

To deploy staples from the staple cartridge, as discussed above, the sled 500 in FIG. 5 can be moved from the proximal end toward a distal end of the cartridge body, and thus, of the staple cartridge. As the firing assembly 400 in FIG. 4 is advanced, the sled can contact and lift staple drivers within the staple cartridge upwardly within the staple cavities 212, 214. In at least one example, the sled and the staple drivers can each include one or more ramps, or inclined surfaces, which can co-operate to move the staple drivers upwardly from their unfired positions. As the staple drivers are lifted upwardly within their respective staple cavities, the staples are advanced upwardly such that the staples emerge from their staple cavities and penetrate into tissue. In various instances, the sled can move several staples upwardly at the same time as part of a firing sequence.

As indicated above, the stapling device can be used in combination with a compressible adjunct. A person skilled in the art will appreciate that, while adjuncts are shown and described below, the adjuncts disclosed herein can be used with other surgical instruments and need not be coupled to a staple cartridge as described. Further, a person skilled in the art will also appreciate that the staple cartridges need not be replaceable.

As discussed above, with some surgical staplers, a surgeon is often required to select the appropriate staples having the appropriate staple height for tissue to be stapled. For example, a surgeon will utilize 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 lead to undesirable leakage and/or tearing of tissue at the staple site when staples with the same or substantially greater height are used, particularly when the staple site is exposed to intra-pressures at the staple site and/or along the staple line.

Accordingly, various examples of adjuncts 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 adjuncts described herein can allow a set of staples with the same or similar heights to be used in stapling tissue of varying thickness (e.g., from thin to thick tissue) while also, in combination with the adjunct, providing adequate tissue compression within and between fired staples. Thus, the adjuncts 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. In addition, exemplary adjuncts described herein may be configured to be absorbed in the body over a period of 100 to 300 days depending on implanted location and tissue health.

Alternatively, or in addition, the adjuncts can be configured to promote tissue ingrowth. In various instances, it is desirable to promote the ingrowth of tissue into an implantable adjunct, 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 adjunct may reduce the incidence, extent, and/or duration of inflammation at the surgical site. Tissue ingrowth into and/or around the implantable adjunct may, for example, manage the spread of infections at the surgical site. The ingrowth of blood vessels, especially white blood cells, for example, into and/or around the implantable adjunct may fight infections in and/or around the implantable adjunct and the adjacent tissue. Tissue ingrowth may also encourage the acceptance of foreign matter (e.g., the implantable adjunct 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.

In general, the adjuncts provided herein are designed and positioned atop a staple cartridge, like staple cartridge 200. When the staples are fired (deployed) from the cartridge, the staples penetrate through the adjunct and into tissue. As the legs of the staple are deformed against the anvil that is positioned opposite the staple cartridge, the deformed legs capture a portion of the adjunct and a portion of the tissue within each staple. That is, when the staples are fired into tissue, at least a portion of the adjunct becomes positioned between the tissue and the fired staple. While the adjuncts described herein can be configured to be attached to a staple cartridge, it is also contemplated herein that the adjuncts can be configured to mate with other instrument components, such as an anvil of a surgical stapler. A person of ordinary skill will appreciate that the adjuncts provided herein can be used with replaceable cartridges or staple reloads that are not cartridge based.

In various embodiments, the adjunct or bioabsorbable materials disclosed herein can be comprised of an absorbable polymer. In certain embodiments, an adjunct can be comprised of foam, film, fibrous woven, fibrous non-woven polyurethane, polyester, polycarbonate, polyorthoester, polyanhydride, polyesteramide, polyoxaester, polyphosphazenes, polyphosphoesters, polyether urethane, polyester urethane, polyester urea, and/or polysaccharide. In other embodiments, an adjunct can be a copolymer including, for example, PGA (polyglycolic acid), PGA/PCL (poly(glycolic acid-co-caprolactone)), PLA/PCL (poly(lactic acid-co-polycaprolactone)), PLLA/PCL, PGA/TMC (poly(glycolic acid-co-trimethylene carbonate)), PDS, PEPBO, and the like. In various embodiments, an adjunct can include an organic material such as, for example, carboxymethyl cellulose, sodium alginate, hyaluronic acid, and/or oxidized regenerated cellulose. In various embodiments, an adjunct has a durometer in the 3-7 Shore A (30-50 Shore 00) ranges with a maximum stiffness of 15 Shore A (65 Shore 00). In certain embodiments, an adjunct can undergo 40% compression under 3 lbf load, 60% compression under 6 lbf load, and/or 80% compression under 20 lbf load, for example. In certain embodiments, one or more gasses, such as air, nitrogen, carbon dioxide, and/or oxygen, for example, can be bubbled through and/or contained within the adjunct.

Methods of Stapling Tissue

FIGS. 6A-6B illustrate an exemplary example of a stapling assembly 600 that includes a staple cartridge 200 and an adjunct 604. For sake of simplicity, the adjunct 604 is generally illustrated in FIGS. 6A-6B, and various configurations of the adjunct are described in more detail below. As shown, the adjunct 604 is positioned against the staple cartridge 200. While partially obstructed in FIGS. 6A-6B, the staple cartridge 200 includes staples 300, that are configured to be deployed into tissue. The staples 300 can have any suitable unformed (pre-deployed) height.

In the illustrated example, the adjunct 604 can be mated to at least a portion of the top surface or deck surface 206 of the staple cartridge 602. In some examples, the top surface 206 of the staple cartridge 200 can include one or more surface features which can be configured to engage the adjunct 604 to avoid undesirable movements of the adjunct 604 relative to the staple cartridge 200 and/or to prevent premature release of the adjunct 604 from the staple cartridge 200. Exemplary surface features are described further below and in U.S. Pat. No. 10,052,104, which is incorporated by reference herein in its entirety.

FIG. 6B shows the stapling assembly 600 placed within and coupled to the elongate channel 610 of surgical end effector 106. The anvil 102 is pivotally coupled to the elongate channel 610 and is thus moveable between open and closed positions relative to the elongate channel 610, and thus the staple cartridge 200. The anvil 102 is shown in a closed position in FIG. 6B and illustrates a tissue gap T_G1created between the staple cartridge 602 and the anvil 612. More specifically, the tissue gap T_G1is defined by the distance between the tissue-compression surface 102a of the anvil 102 (e.g., the tissue-engaging surface between staple forming pockets in the anvil) and the tissue-contacting surface 604a of the adjunct 604. In this illustrated example, both the tissue-compression surface 102a of the anvil 102 and the tissue-contacting surface 604a of the adjunct 604 is planar, or substantially planar (e.g., planar within manufacturing tolerances). As a result, when the anvil 102 is in a closed position, as shown in FIG. 6B, the tissue gap T_G1is generally uniform (e.g., nominally identical within manufacturing tolerances) when no tissue is disposed therein. In other words, the tissue gap T_G1is generally constant (e.g., constant within manufacturing tolerances) across the end effector 106 (e.g., in the y-direction). In other examples, the tissue-compression surface of the anvil can include a stepped surface having longitudinal steps between adjacent longitudinal portions, and thus create a stepped profile (e.g., in the y-direction). In such examples, the tissue gap T_G1can be varied.

The adjunct 604 is compressible to permit the adjunct to compress to varying heights to thereby compensate for different tissue thickness that are captured within a deployed staple. The adjunct 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 adjunct 604 can have an uncompressed height which is greater than the fired height of the staples 300 disposed within the staple cartridge 200 (e.g., the height (H) of the fired staple 300a in FIG. 7A). That is, the adjunct 604 can have an undeformed state in which a maximum height of the adjunct 604 is greater than a maximum height of a fired staple (e.g., a staple that is in a formed configuration).

In use, once the surgical stapling and severing device, like device 100 in FIG. 1, is directed to the surgical site, tissue is positioned between the anvil 102 and the stapling assembly 600 such that the anvil 102 is positioned adjacent to a first side of the tissue and the stapling assembly 600 is positioned adjacent to a second side of the tissue (e.g., the tissue can be positioned against the tissue-contacting surface 604a of the adjunct 604). Once tissue is positioned between the anvil 102 and the stapling assembly 600, the surgical stapler can be actuated, e.g., as discussed above, to thereby clamp the tissue between the anvil 102 and the stapling assembly 600 (e.g., between the tissue-compression surface 102a of the anvil 102 and the tissue-contacting surface 604a of the adjunct 604) and to deploy staples from the cartridge through the adjunct and into the tissue to staple and attach the adjunct to the tissue.

As shown in FIG. 7A, when the staples 300 are fired, tissue (T) and a portion of the adjunct 604 are captured by the fired (formed) staples 300a. The fired staples 300a each define the entrapment area therein, as discussed above, for accommodating the captured adjunct 604 and tissue (T). The entrapment area defined by a fired staple 300a is limited, at least in part, by a height (H) of the fired staple 300a.

Referring to FIG. 7B, the adjunct 604 may have pores 632 with a median pore size of about 0.025 mm³to about 0.300 mm³, such as about 0.022 mm³. In some examples, the adjunct 604 may have one or more struts 634 between the pore 632 that provide support and strength to the adjunct 604. In particular, the adjunct 604 may include a plurality of struts 634, having a median strut thickness ST of about 0.025 mm to about 0.300 mm, such as about 0.08 mm.

FIG. 8 illustrates a perspective view of a staple cartridge assembly 600 with an adjunct 604 and a staple cartridge 200. The adjunct 604 has a tissue contacting surface 604a, a proximal end 604c, and a distal end 604b. The adjunct 604 may include a slot/slit 808 separating or partially separating two parallel portions of the adjunct 604. In one example, adjunct 604 may include a slot 808 separating two parallel portions of the adjunct 604, while in another example, adjunct 604 may include a slit 808 separating two parallel portions of the adjunct 604 and also one or more bridges (e.g., five bridges) 802 connecting the two parallel portions of the adjunct 604. At least one bridge has a length in the longitudinal direction of about 0.035 inches to about 0.046 inches. The adjunct 604 has a length L of about 40 mm to about 80 mm, such as about 60 mm to about 65 mm, about 66.04 mm to about 66.3 mm, about 45 mm to about 55 mm, or about 51.12 mm to about 51.38 mm. The adjunct 604 has a width W of about 8 mm to about 12 mm, such as about 9.75 mm to about 10.25 mm or about 10.025 mm to about 10.035 mm. The adjunct 604 may also have a thickness or height TH of about 2.5 mm to about 3.5 mm, such as about 2.85 mm to about 3.15 mm or about 2.95 mm to about 3.05 mm.

The cartridge 200 has a height CH of about 6.3 mm to about 8.1 mm, a width CW of about 8.9 mm to about 14 mm, and a length CL of about 80 mm to about 90 mm such as about 86.7 mm.

The staple cartridge 200 may include one or more raised ledges 804 along one or more sides of the adjunct 604 to help align the adjunct 604 on the deck of the staple cartridge 200. Although not shown in FIG. 8, the staple cartridge 200 may also include an adhesive or buttress adhesive material to attach the adjunct 604. The adjunct 604 may be attached to the cartridge 200 with about 100 mg to about 120 mg of the adhesive or buttress adhesive material.

Spatial Control of Mechanical Properties Through Selective Crosslinking Density

As described above, the end effector 106 (shown in FIG. 1) comprising the cartridge 200 and adjunct 604 is closed or substantially closed for inserting through a trocar to the delivery site. During delivery, the surgical adjunct 604 needs to have mechanical properties such that the material is sufficiently compressible, but must have increased strength to retain staples, sutures, and screws at the delivery site. The surgical adjunct 604 can be tuned the particular purpose before, during, and after surgical procedures and have one or more of the properties described below that modulate the mechanical properties. In particular, the adjunct 604 described has selective crosslinking density control in vivo and can also have a certain compressibility when attached to the cartridge outside of the body.

Turning to FIGS. 9A and 9B, example staple cartridge assemblies 900a, 900b with spatial control of mechanical properties include an adjunct 604 having two or more zones such as a first zone 636 and a second zone 638. In some examples, the first zone 636 and the second zone 638 may be distinct. The first zone 636 of the porous body 634 includes a first crosslink density, while the second zone 638 has a second crosslink density different than the first zone 636. As shown in the staple cartridge assembly 900a, the second zone 638 can be positioned approximately central along a longitudinal axis Lp of the porous body 634. Another orientation of spatial control of a cartridge assembly 900b is provided in FIG. 9B, where more than one second zone 638 is positioned along the longitudinal axis to provide a gradient of crosslink density laterally. As shown in FIG. 9B, the second zone 638 can be positioned centrally along each half of the adjunct 604. In some examples, the spatial control shown in FIG. 9B may provide for an optional slot/slit 808 separating or partially separating two parallel portions of the adjunct 604, as shown in FIG. 8.

As would be appreciated by one of skill in the art, such spatial control could be more optimal for tissue in-growth or hemostatic behavior. Further, the gradient could also be compositional with a varying bio-absorption profile. A short-term absorption profile may be preferred to address hemostasis while a long-term absorption profile may address better tissue healing without leakages.

FIGS. 9C and 9D provide example staple cartridge assemblies 900c, 900d with spatial control of mechanical properties include an adjunct 604 having a first zone 636 and a second zone 638 positioned at approximately opposing ends of the adjunct 604, such as at the proximal end 604c and a distal end 604b. In some embodiments, the second zone 638 at the proximal end 604c and distal end 604b of the adjunct 604 can be substantially equal in length, as illustrated in FIG. 9C. Alternatively, the second zone 638 can be substantially greater in length at the distal end 604b of adjunct 604, where it may be desirable to modulate the crosslink density where the compression between the anvil and the cartridge 200 initiates. Although not depicted, an orientation where the second zone is substantially greater in length at the proximal end 604c of the adjunct 604 is also contemplated. In some examples, the spatial control shown in FIGS. 9C and 9D may provide for an optional slot/slit 808 separating or partially separating two parallel portions of the adjunct 604, as shown in FIG. 8.

In some embodiments, an example staple cartridge assembly with spatial control of mechanical properties can include an adjunct 604 having a first zone 636 and a second zone 638, where the second zone 638 is positioned over at least a portion of one side of the first zone 636. For instance, the second zone 638 can coat over the first zone 636 on at least one side, or alternatively on two sides, or all sides. The coating can be resistant or substantially resistant to absorption at certain pH, such as, for example, acidic conditions (pH<7) such that the coating can be used for tissue at or near the stomach. In other examples, the coating can delay absorption time for a predetermined timeframe and prevent the bulk material of the adjunct from contacting fluids.

The adjunct 604 has a porous body 634 made of at least one polymer that can undergo selective crosslinking via photocurable networks, monomer incorporation, stimuli responsive functional groups, and the like. The polymer may include polyurethane, polyester, polycarbonate, polyorthoester, polyanhydride, polyesteramide, and/or polyoxaester.

To achieve control of crosslink density, the polymer of the porous body 634 can have or be mixed with a polymerizable compound having functional groups that act as crosslinkable units.

In some embodiments, the polymerizable compound is a chain extender that does not contribute to crosslinking. The chain extender can be incorporated in the polymer's monomer backbone or as pendent groups. In some examples, the chain extender is carbon-carbon based and has double bonds that incorporate within the polymer backbone. As a non-limiting example, a fumaric acid can be added during the condensation reaction of the polymer backbone of the porous body. With the addition of a photoinitiator, the fumaric acid in the polymer backbone would provide a crosslinking site that is specifically controlled by lithography through the photocurable site. In addition, upon degradation of the porous body, such as in the body after a surgical procedure, dimethyl fumarate could be selectively generated from the polymer backbone. Dimethyl fumarate is a known Nrf2 activator that can be used to secondarily treat inflammation and prevent nerve damage.

In another example, the chain extender replaces one or more of the functional groups on the polymer backbone such that the crosslinking is reduced. For instance, in a polyurethane polymer backbone, a chain extender such as acrylate or methacrylate can replace one of the hydroxyl groups from the polyol. The chain extender can be fumaric acid, succinic acid, maleic acid, and/or combinations thereof.

Returning to FIGS. 9A-9D, the polymerizable compound is added only to the first zone 636 or only to the second zone 638 such that the porous body 643 has differing crosslink densities around the middle row of staples, or around staple pockets and between rows of staples. As would be appreciated by one of skill in the art, utilizing a lower crosslink density in the middle row, where the amount of pressure is lowest compared to the first and third rows, can result in a lower force required to fire the staples while maintaining the necessary compressive properties across the entire staple line.

Alternatively, the polymerizable compound can be added to both the first zone 636 and second zone 638, but in different concentrations. For example, the plasticizer (e.g., polyethylene glycol 200 (PEG-200)) may be included as a separate chemical additive or as a chemical backbone within a polymer. In another embodiment, polymerizable compounds having different functional groups and crosslink density can be added to one of the first zone 636 or the second zone 638. In some embodiments, the polymerizable compounds can be added before, during, or after the formation of the porous body.

In some embodiments, the change in crosslink density between the first zone 636 and second zone 638 forms a gradient of compression strength along a portion of the porous body 634. In general, the adjunct 604 may have a compression strength of about 30 kPa to about 70 kPa, such as about 30 kPa to about 60 kPa (e.g., about 42 kPa), about 30 kPa to about 50 kPa, about 32.5 kPa to about 37.5 kPa. In some embodiments, the adjunct 604 may have a compression strength of about 30 kPa to about 70 kPa in the first zone, and a compression strength of about 15 to about 50 kPa in the second zone. In order to test compression strengths, an adjunct 604 was placed in a humid warm environment at approximately 37° C., compressed to a first height (e.g., about 1.75 mm), then a second height shorter than the first height, and then released back to the first height at which point the adjunct's compression strength was measured.

In some examples, the adjunct 604 may have a tensile strength of about 30 kPa to about 90 kPa such as about 45 kPa to about 85 kPa or about 55 kPa to about 75 kPa. In some examples, the adjunct 604 will have tensile strength of about 110 kPa to about 150 kPa. Specifically, the adjunct's 604 tensile strength may be measured after submerging it in water at a temperature of about 37° C. for less than a minute and then running a tensile strength test.

In some embodiments, the polymerizable compound is a crosslinking monomer added to the polymer backbone that is specifically undercured and retains reactive sites within the network. Additional crosslinking monomers can be deposited or otherwise applied onto or within the porous body in patterned locations to increase the mechanical properties locally. In one non-limiting example, a polymer backbone having isocyanate functional groups, a polyol crosslinking monomer can be added to increase crosslinking at the specific addition location, for example, along only one of the first zone 636 or second zone 638, as shown in FIGS. 9A and 9B. Because monofunctional alcohols act as capping agents to isocyanate functional groups, a monofunctional alcohol can be added to the zone intended to maintain the crosslink density. The crosslinking monomer can be an arylboronic acid, a styrylpyrene, a styrene, and combinations thereof.

In some embodiments, direct crosslinking monomer addition can be done through any suitable technique including, without limitation, inkjet printing, direct deposition, thermal spraying, cold dynamic spraying, cold spraying, electro spraying, ultrasonic spray coating, dip coating, screen printing, spin coating, and the like.

In yet another embodiment, the polymerizable compound is a stimuli-responsive functional group that can undergo reversible crosslinking upon exposure to one or more of heat, light, ultrasound waves, pH, counter ion exchange, and combinations thereof. Example stimuli-responsive functional groups include o-nitrobenzyl, coumarin, anthracene, disulfide, diselenide, Diels-Alder (diene and dienophile). Stimuli-responsive functional groups can allow for crosslink density transition from linear to complex architectures such as star, cyclic, or hyperbranched. The stimuli-responsive functional groups can include a vinyl acetate, an acrylonitrile, a vinylidene dichloride, an isoprene, a butadiene, a chloroprene, and/or combinations thereof.

In any of the embodiments disclosed herein, the polymerizable compound can modulate the crosslink density (and the mechanical properties of porous body) for a predetermined time frame. For instance, a crosslink density change may occur over several seconds or minutes such that upon delivery, the porous body is readily compressible, and the end effector is easily inserted through the trocar and after the induction period passes, the mechanical strength of the porous body increases in specific zones as a function of spatial arrangements (e.g., the first zone 636 of FIG. 9A).

FIG. 10A is a side view of the end effector 106 in a delivery configuration, where the adjunct 604 is compressible between the anvil 102 and the cartridge 200. As illustrated, the end effector 106 can include a staple cartridge 200 an adjunct 604 comprising a bioabsorbable material. In certain embodiments, the adjunct 604 is releasably retained on the cartridge 200. When the end effector 106 closes around tissue T, the adjunct 604 can compress from a thickness of the uncompressed adjunct UT to a thickness of compressed adjunct CT of adjunct in response to a variation in tissue thickness.

FIG. 10B is a side view of the end effector 106 after firing of staples 300, where the adjunct 604 is no longer compressed between the anvil 102 and the cartridge 200. As shown, the adjunct 604 is released from the cartridge 200 after firing. The adjunct 604 is shown to maintain the thickness of the compressed adjunct CT and the thickness of uncompressed adjunct UT from pre-firing in FIG. 10A. In some embodiments, the adjunct 604 can undergo a change in crosslink density before firing of staples such that the adjunct height PH and compressed portion CT will be maintained after firing and releasing adjunct 604 and tissue T. In other embodiments, the adjunct 604 can undergo crosslink density changes after a predetermined timeframe, as described above. In such an example, the adjunct height PH and compressed portion CT can either expand or contract in response to the staple height and the tissue thickness. As would be appreciated by those of skill in the art, a change in crosslink density of the adjunct 604 can be advantageous to ensure a hemostatic seal during changes in tissue inflammatory responses and throughout the healing process.

FIGS. 11A and 11B show top and side view of an adjunct 604 after firing staples 300 and cutting tissue T. As shown, adjunct 604 may split in two post firing. Where the adjunct 604 contacts with the tissue T, bumps 604e, 604f may form that correspond to the texture and thickness variation in the tissue. This means that adjunct 604 can adapt to different heights and compressions depending on the application.

FIG. 12 is a flowchart of a method 1200 of forming surgical adjunct 604, including a bioabsorbable material that itself includes a porous body. The techniques for spatial control of mechanical properties described herein may offer an added benefit of increasing adjunct strength and durability in combination with positive in vivo interactions (e.g., biocompatibility, wound healing, tissue integration, chemotherapy, anti-inflammatory, bone growth and integration, ligament and tendon repair, etc.) when the adjunct is delivered to the tissue site, as described herein. As such, the techniques described herein may allow the bioabsorbable material itself to aid in the healing process of the surrounding tissue. In addition, the embedding techniques described herein may offer an added benefit of preventing fibrous encapsulation of the foam cushion, and/or providing tunable release profiles for a variety of medical additives delivered to the tissue site.

Specifically with respect to FIG. 12, the method 1200 used for spatial control of mechanical properties in a bioabsorbable material (e.g., a foam) may include chemically reacting a polyol and an isocyanate to form a porous body (step 1202). In some examples, the bioabsorbable material may include a polyurethane. Method 1200 also includes adding a polymerizable compound to at least a portion of the porous body (step 1204). The polymerizable compound is at least one of a chain extender and a photoinitiator. After introduction of the polymerizable compound, method 1200 includes exposing the porous body and the polymerizable compound to at least one of heat, light, ultrasound waves, and pH (step 1206). Method 1200 can end after step 1206 or can optionally include adding a medical additive to the porous body (optional step 1208). In such examples, the medical additives may include medicants to treat pain and/or promote wound healing, tissue growth, infection reduction, and the like. In similar methods, crosslink density may be varied through other process parameters besides adding a polymerizable compound. For example, it is envisioned that the chemical backbone of the bioabsorbable material may be changed from one zone to another or the density may be changed from one zone to another by manipulated mechanical or other chemical properties when producing the bioabsorbable material.

As will be appreciated by one skilled in the art, The embodiments described above are cited by way of example, and the present invention is not limited by what has been particularly shown and described hereinabove. Rather, the scope of the invention includes both combinations and sub combinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.

In some examples, disclosed devices (e.g., end effector, surgical adjunct, and/or staple cartridges) and methods involving one or more disclosed devices may involve one or more of the following clauses:

Clause 1: A bioabsorbable material configured to be delivered to tissue, the material comprising: a porous body comprising at least one polymer comprising: a first zone comprising a first crosslink density; and a second zone comprising a second crosslink density different than the first zone, wherein at least the first and second zones form a gradient of compression strength along a portion of the porous body.

Clause 2: The material of clause 1, wherein the porous body comprises polyurethane and at least one of the first zone and the second zone comprises a polymerizable compound comprising crosslinkable units, the polymerizable compound configured to react with the polyurethane and undergo crosslinking between crosslinking units upon exposure to a stimulation.

Clause 3: The material of clause 2, wherein the stimulation comprises at least one of heat, light, ultrasound waves, and pH.

Clause 4: The material of clause 2, wherein the polymerizable compound comprises at least one of a chain extender, a reactive monomer, a photoinitiator and a stimuli-responsive functional group; and wherein at least one of the chain extender, reactive monomer, photoinitiator and stimuli-responsive functional group are configured to modulate an amount of crosslinking between crosslinking units.

Clause 5: The material of clause 4, wherein the chain extender comprises fumaric acid, succinic acid, maleic acid, or combinations thereof.

Clause 6: The material of clause 2, wherein the polymerizable compound comprises an acrylate, a methacrylate, an arylboronic acid, a styrylpyrene, a styrene, a vinyl acetate, an acrylonitrile, a vinylidene dichloride, an isoprene, a butadiene, a chloroprene, or combinations thereof.

Clause 7: The material of clause 2, wherein the polymerizable compound is further configured to degrade to form a degradation product, and wherein the degradation product functions as a medicament when released at or approximate the tissue.

Clause 8: The material of clause 1, wherein the second zone is positioned approximately central along a longitudinal axis of the porous body (LP).

Clause 9: The material of clause 1, wherein the second zone is positioned at approximately opposing ends of the porous body.

Clause 10: The material of clause 1, wherein the second zone is coated over at least one side of the first zone.

Clause 11: The material of clause 10, wherein the coating comprises a thickness of about 20 μm to about 100 μm.

Clause 12: The material of clause 1, wherein the foam has a compression strength of about 30 to about 70 kPa in the first zone, and a compression strength of about 15 to about 50 kPa in the second zone.

Clause 13: The material of clause 1, wherein the second zone comprises a lower crosslinking density than the first zone.

Clause 14: A method to form a bioabsorbable material, the method comprising the steps of: chemically reacting a polyol and an isocyanate to form a porous body; and adding a polymerizable compound to at least a portion of the porous body, wherein the polymerizable compound comprises crosslinkable units, the polymerizable compound configured to undergo crosslinking between the crosslinking units upon exposure to a stimulation and modulate a crosslinking density in the porous body.

Clause 15: The method of clause 14, wherein the porous body comprises polyurethane.

Clause 16: The method of clause 14, wherein the polymerizable compound comprises at least one of a chain extender, a reactive monomer, a photoinitiator and a stimuli-responsive functional group, wherein at least one of the chain extender, reactive monomer, photoinitiator and stimuli-responsive functional group are configured to modulate an amount of crosslinking between the crosslinking units upon exposure to the stimulation.

Clause 17: The method of clause 14, further comprising the step of: applying the polymerizable compound approximately centrally along a longitudinal axis of the porous body.

Clause 18: The method of clause 14, further comprising the step of: applying the polymerizable compound at approximately opposing ends of the porous body.

Clause 19: The method of clause 14, further comprising the step of: exposing the porous body and the polymerizable compound to at least one of heat, light, ultrasound waves, and pH.

Clause 20: The method of clause 14, further comprising the step of: adding a medical additive to the porous body, wherein the one or more medical additives are further configured to chemically bond with the polymerizable compound and be released at or approximate the tissue over a predetermined period of time.

Clause 21: A bioabsorbable material configured to be delivered to tissue, the material comprising: a porous body comprising at least one polymer comprising: a first zone comprising a first crosslink density; and a second zone comprising a second crosslink density different than the first zone, wherein the first and second zones form a gradient of compression strength along a portion of the porous body.

Clause 22: The material of clause 21, wherein the porous body comprises polyurethane and at least one of the first zone and the second zone comprises a polymerizable compound comprising crosslinkable units, the polymerizable compound configured to react with the polyurethane and undergo crosslinking between crosslinking units upon exposure to a stimulation.

Clause 23: The material of clauses 21-22, wherein the stimulation comprises at least one of heat, light, ultrasound waves, and pH.

Clause 24: The material of any of clauses 22-23, wherein the polymerizable compound comprises at least one of a chain extender, a reactive monomer, a photoinitiator and a stimuli-responsive functional group; and wherein at least one of the chain extender, reactive monomer, photoinitiator and stimuli-responsive functional group are configured to modulate an amount of crosslinking between crosslinking units.

Clause 25: The material of clause 24, wherein the chain extender comprises fumaric acid, succinic acid, maleic acid, or combinations thereof.

Clause 26: The material of any of clauses 22-25, wherein the polymerizable compound comprises an acrylate, a methacrylate, an arylboronic acid, a styrylpyrene, a styrene, a vinyl acetate, an acrylonitrile, a vinylidene dichloride, an isoprene, a butadiene, a chloroprene, or combinations thereof.

Clause 27: The material of any of clauses 22-26, wherein the polymerizable compound is further configured to degrade to form a degradation product, and wherein the degradation product functions as a medicament when released at or approximate the tissue.

Clause 28: The material of any of clauses 21-27, wherein the second zone is positioned approximately central along a longitudinal axis of the porous body.

Clause 29: The material of any of clauses 21-27, wherein the second zone is positioned at approximately opposing ends of the porous body.

Clause 30: The material of any of clauses 21-27, wherein the second zone is coated over at least a portion of one side of the first zone.

Clause 31: The material of any of clauses 28-30, wherein the second zone comprises a thickness of about 20 μm to about 100 μm.

Clause 32: The material of any of clauses 21-31, wherein the material comprises a compression strength of about 30 to about 70 kPa in the first zone, and a compression strength of about 15 to about 50 kPa in the second zone.

Clause 33: The material of any of clauses 21-32, wherein the second zone comprises a lower crosslink density than the first zone.

Clause 34: The material of any of clauses 21-33, further comprising one or more medical additives configured to remain chemically bonded with the polymerizable compound in at least one of the first zone or the second zone.

Clause 35: The material of clause 34, wherein the one or more medical additives are further configured to be released at or approximate the tissue over a predetermined period of time.

	Number	Date	Country
Parent	63522660	Jun 2023	US
Child	18484988		US

SYSTEMS AND METHODS FOR CUSTOMIZING CROSSLINKING DENSITY IN BIOABSORBABLE MATERIALS

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