Material combinations and processing methods for surgical instruments

Abstract

To provide improved surgical instruments. [Solution] Surface preparation of sliding surfaces can improve the wear performance of surgical instruments such as surgical staplers, which include a reusable mechanism that is used multiple times with a single-use reloadable cartridge. A combination of surface hardening, surface finishing, and surface coating can be applied to the metal components of surgical instruments to reduce the possibility of abrasive wear in metal-to-metal sliding engagements. Surface hardening technology can enable further manufacturing operations such as welding without compromising the strength of the underlying metal substrate. With stainless steel metal substrates, surface hardening or surface hardening technology may reduce corrosion resistance, so a surface coating can be added to suppress surface oxidation and to provide a barrier against metal-to-metal contact. Further lubricating coating layers, such as a brazing coating layer, can enhance abrasion resistance.

Description

Technical Field

[0001] 〔Cross - Reference to Related Applications〕 This application claims priority and the benefit thereof to U.S. Provisional Patent Application No. 63 / 107,321, entitled "Material Combinations and Processing Methods for a Surgical Instrument", filed on October 29, 2020, which is hereby incorporated by reference in its entirety.

[0002] This application generally relates to surgical instruments, and more particularly to material combinations and processing methods for sliding components within the end effector of a surgical instrument, such as a surgical stapling device.

Background Art

[0003] Surgical staplers are used to access or clamp tissue and staple clamped tissue together. Thus, surgical staplers have mechanisms to ensure that the tissue is properly positioned and captured and to drive staples through the tissue. As a result, this has led to the creation of, for example, multiple triggers and handles along with complex mechanisms to provide proper stapling of the clamped tissue. These complex mechanisms can lead to an increased manufacturing burden, as well as potential causes of device failure and confusion for the user. That is, reliable stapling of clamped tissue without complex mechanisms is desirable.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] The surgical stapler may further include a replaceable reloadable cartridge that allows multiple cartridges to be used with the stapler in a single surgical procedure. The clamping and firing mechanism of the surgical stapler may include metal components that are in sliding contact. Further improvements to the sliding contact components are desirable to counteract wear degradation over multiple firing cycles. [Means for solving the problem]

[0006] In certain embodiments, surgical stapling devices are provided herein. The surgical stapling device comprises an end effector and a launching member. The end effector comprises a first jaw and a second jaw pivotably coupled to the first jaw. The launching member is longitudinally slidable relative to the end effector to pivotably move the second jaw relative to the first jaw in order to actuate the end effector. At least one of the first jaw, the second jaw and the launching member comprises a metal substrate, a dry film surface coating disposed on the metal substrate, and a bone wax layer disposed on the dry film surface.

[0007] In certain embodiments, a surgical stapler is provided herein. The surgical stapler comprises an elongated shaft and a jaw assembly. The elongated shaft extends from a proximal end to a distal end. The jaw assembly is positioned at the distal end of the elongated shaft. The jaw assembly comprises a cartridge support, an anvil, and a launching member. The cartridge support is configured to receive a reloadable cartridge in which a plurality of staples are arranged. The cartridge support and anvil are pivotably movable between an open configuration and a closed configuration. The launching member is longitudinally slidable in the closed configuration, engaging with the cartridge support and anvil to launch staples. At least one of the anvil, cartridge support, and launching member comprises a surface-hardened metal substrate, a dry film surface coating disposed on the metal substrate, and a bone wax layer disposed on the dry film surface.

[0008] In certain embodiments, a method for manufacturing a surgical end effector is provided herein. The method comprises the steps of providing a first jaw member, a second jaw member, and a launching member, each having a metal substrate. The method further comprises the steps of curing at least one of the metal substrates of the first jaw member, the second jaw member, and the launching member to a first predetermined hardness. The method further comprises the steps of applying a dry film coating to at least one of the cured first jaw member, the second jaw member, and the launching member. The method further comprises the steps of applying a bone sap composition to at least one of the first jaw member, the second jaw member, and the launching member. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of an embodiment of a surgical stapling device. [Figure 2] Figure 1 is a perspective view of an embodiment of a shaft assembly and jaw assembly for use with the surgical stapling device. [Figure 3]Figure 1 is a perspective view of an embodiment of a jaw assembly and reload cartridge for use with the surgical stapling device. [Figure 4] Figure 3 is a cross-sectional perspective view of the proximal end of the jaw assembly. [Figure 5] Figure 3 is a cross-sectional perspective view of the jaw assembly. [Figure 6] This graph shows an illustrative force-to-progress plot for an exemplary embodiment of a jaw assembly. [Figure 7] This graph shows an illustrative force-to-progress plot for another exemplary embodiment of the jaw assembly. [Figure 8] This graph shows an illustrative force-to-progress plot for another exemplary embodiment of the jaw assembly. [Figure 9A] This is a schematic diagram of a cross-section of a metal substrate for an exemplary embodiment of the components of a surgical stapler. [Figure 9B] This is a schematic cross-sectional view of a metal substrate to another exemplary embodiment of the components of a surgical stapler. [Figure 10] This figure shows an exemplary method for preparing the surfaces of components of a surgical stapler. [Modes for carrying out the invention]

[0010] Referring to Figures 1 and 2, embodiments of a surgical stapling device are illustrated. The illustrated embodiment of the surgical stapler 10 comprises an elongated shaft 20, a jaw assembly 30, and a handle assembly 40. Various embodiments of the elongated shaft 20 and jaw assembly 30 described herein can be used interchangeably with either a mechanical handle assembly 40, such as the illustrated one, or an electrically operated handle assembly 40, for example, including an electric motor. Furthermore, embodiments of the elongated shaft 20 and jaw assembly 30 described herein are intended to be used with a shaft assembly configured to be actuated by a robotic surgical system. Figure 1 shows the surgical stapler 10 with the jaw assembly 30 in an open configuration. Figure 2 shows a removable reloadable shaft assembly comprising the elongated shaft 20 and jaw assembly 30 of the surgical stapler 10 with the jaw assembly 30 in an open configuration.

[0011] Continuing with reference to Figures 1 and 2, the illustrated embodiment of the surgical stapler 10 has and can be sized for use in laparoscopic surgical procedures. For example, the elongated shaft 20 and jaw assembly 30 have and can be sized for introduction into the surgical field through an access port or trocar cannula. In some embodiments, the elongated shaft 20 and jaw assembly 30 have and can be sized for insertion through a trocar cannula having a relatively small working channel diameter, such as less than 8 mm. In other embodiments, the elongated shaft 20 and jaw assembly 30 have and can be sized for insertion through a trocar cannula having a larger working channel diameter, such as 10 mm, 11 mm, 12 mm, or 15 mm. In other embodiments, certain aspects of the surgical stapler described herein are designed to be incorporated into a surgical stapling device for use in open abdominal surgery procedures.

[0012] Continuing to refer to FIGS. 1 and 2, in the illustrated embodiment, the jaw assembly 30 is coupled to the elongate shaft 20 at the distal end 24 of the elongate shaft. The jaw assembly 30 includes a first jaw 34 pivotally coupled to a second jaw 32. In the embodiment shown in FIGS. 1-2, the jaw assembly is pivotally coupled to the elongate shaft such that the jaw assembly can be selectively positioned at an articulation position relative to the central longitudinal axis L of the jaw assembly. The handle assembly of FIG. 1 includes an articulation knob 190 and an articulation mechanism configured to provide continuous selectable articulation of the jaw assembly of the elongate shaft assembly through an articulation range. In an initial configuration, the second jaw 32 includes a plurality of staples positioned within a reload cartridge 50 positioned therein. That is, the second jaw 32 defines a reload support.

[0013] Continuing to refer to FIGS. 1 and 2, in the illustrated embodiment, the jaw assembly 30 can be actuated from an open configuration (FIG. 1) to a closed configuration and further to a stapling configuration by an actuating member or beam that is longitudinally slidable within the elongate shaft. In an initial position, the beam can be positioned at the distal end 24 of the elongate shaft 20. With the beam in the initial position, the first jaw 34 is pivotally rotated away from the second jaw 32 such that the jaw assembly 30 is in an open configuration. The actuating beam engages the first jaw 34 upon translation of the distal actuating member or beam parallel to the longitudinal axis L. Translation of the actuating beam a first distance distally from the initial position can actuate the jaw assembly from the open configuration to the closed configuration. With the jaw assembly 30 in the closed configuration, the actuating beam can be translated proximally the first distance to return the jaw assembly 30 to the open configuration. The distal end of the actuating beam is configured to advance a staple slider configured to deploy a plurality of staples 36 from the second jaw 32 upon a further translation of the actuating beam distally beyond the first distance.

[0014] Referring to Figures 1-3, in the illustrated embodiment, the handle assembly is coupled to the elongated shaft 20 at its proximal end 22. As shown, the handle assembly 40 has a pistol grip configuration having a housing that defines a fixed handle 42 and a movable handle 44 or trigger pivotably coupled to the fixed handle 42. In other embodiments, surgical stapler devices including the embodiments described herein are conceivable to have a handle assembly having other configurations, such as a scissor-grip configuration or an in-line configuration. The handle assembly 40 houses an actuation mechanism configured to selectively advance the actuation shaft in response to the movement of the movable handle 44 to actuate the actuation beam in the elongated shaft by a first distance in an open-close stroke, close the jaw assembly from an initial open position by a second distance beyond the first distance in a firing stroke that fires staples, and return the actuation beam by the second and first distances to the initial position. In certain embodiments, a sliding selector 72 on the handle assembly allows the user to select whether the handle assembly is operated to actuate the jaw assembly in an open-close stroke or in a firing stroke. Various embodiments of the handle assembly and associated actuation mechanisms are disclosed in U.S. Patent No. 9,668,732, entitled "Surgical Stapler Handle Assembly Having Actuation Mechanism With Longitudinal Rotatable Shaft," and U.S. Patent Application No. 15 / 485,620, filed April 12, 2017, entitled "Surgical Stapler Having Articulation Mechanism," both of which are incorporated herein by reference in their entirety.

[0015] Continuing to refer to FIGS. 1-3, in some embodiments, the surgical stapler 10 can include a plurality of staples positioned within a disposable reload cartridge 50, while the handle assembly 40 and the elongate shaft 20 are configured to be reused with a plurality of staple reload cartridges. In certain embodiments, each reload cartridge 50 can be coupled to a reload cover 150 to shield the tissue contact surface and staple pockets of the reload cartridge prior to attachment to the jaw assembly, and the reload cover 150 is to be removed prior to the surgical stapler being introduced into the surgical site. The handle assembly 40 and the elongate shaft 20 can be desirably resistant to performance degradation associated with wear so as to reliably operate the stapler for a plurality of clamping and staple firing cycles each including a single-use reload cartridge 50. The surgical stapler can include one or more gripping and firing lockout mechanisms that can limit the function of the handle assembly and warn the user, and enhance patient safety, when the reload cartridge is not present in the jaw assembly or when a partially or fully fired reload cartridge is present in the jaw assembly. In certain embodiments, a staple deployment member, such as a sled or slider that is translatable within the reload cartridge 50, can overcome one or more lockout mechanisms when the staple deployment member is in a proximal position of the jaw assembly corresponding to a state where an unfired reload cartridge is present within the surgical stapler 10.

[0016] Referring to Figure 1, the handle assembly 40 is provided with a coupler 46 at its distal end. The coupler 46 is configured to engage with the elongated shaft 20 of the surgical stapler 10. The coupler 46 may have a bayonet connection having an outer connector that can detachably connect the handle assembly 40 to the elongated shaft 20 and an inner connector that can detachably connect the working shaft of the handle assembly 42 to the working member of the elongated shaft 20. That is, the surgical stapler 10 can be configured so that the handle assembly 40 can be reused with multiple disposable shafts and / or reloadable cartridges during a surgical procedure. In other embodiments, the handle assembly and some part of the elongated shaft can be reused, while the remainder of the elongated shaft and the jaw assembly define a disposable cartridge. In certain other embodiments, the handle assembly and elongated shaft can be reused, while the jaw assembly defines a disposable cartridge. In yet another embodiment, a jaw insert that accommodates multiple staples can define a disposable cartridge, while the remainder of the surgical stapler is reusable.

[0017] As described herein, the shaft assemblies, jaw assemblies, and reload cartridges described herein can be used in conjunction with actuators for powered stapler handle assemblies or robotic surgical systems. Various embodiments of powered handle assemblies and associated operating mechanisms are disclosed in U.S. Patent Application No. 15 / 486,227, filed April 12, 2017, entitled "Reload Shaft Assembly for Surgical Stapler," U.S. Patent Application No. 15 / 486,008, filed April 12, 2017, entitled "Surgical Stapler Having a Powered Handle," and U.S. Patent Application No. 16 / 287,748, filed February 27, 2019, entitled "Surgical Stapler Having a Powered Handle," all of which are incorporated herein by reference in their entirety.

[0018] Referring to Figure 3, a perspective view of the jaw assembly of the elongated shaft 20 with the reload cartridge 50 removed from the second jaw 32 is shown. As shown, the reload cartridge 50 is removably positioned on a reload support defined by the second jaw 32. In the illustrated embodiment, the reload cartridge 50 includes a plurality of staples disposed therein, each staple positioned within its own staple pocket formed through the body of the reload cartridge. The upper surface of the reload cartridge 50 defines a tissue contact surface which can be substantially planar in certain embodiments. The reload cartridge further includes a blade channel formed therein. As shown, the blade channel extends longitudinally between rows of staple pockets, so that the parallel movement of a cutting blade passing through the blade channel transversely cuts the tissue between rows of staples deployed within the tissue positioned in the jaws when the staples are fired. The reloading support defined by the second jaw 32 is sized to removably receive the reloading cartridge 50 and includes a channel configured to do so. For example, in certain embodiments, the channel of the reloading support may include at least one recess 132 sized to receive a corresponding protruding boss on the reloading cartridge 50 and configured to do so.

[0019] Referring to Figure 4, an embodiment of the jaw assembly is illustrated. The cross-section of the jaw assembly is oriented substantially perpendicular to the longitudinal axis of the jaw assembly at the proximal end of the jaw assembly, just distal to the distal end 24 of the elongated shaft, to facilitate visibility of certain aspects of the operation of the surgical stapler in the closure / tissue clamping and firing operations. In the illustrated embodiment, the surgical stapler includes an actuation mechanism that includes a firing member 120 that is longitudinally translatable within the first jaws 34 and second jaws 32 of the jaw assembly to actuate the jaw assembly from an open configuration to a closed configuration and subsequently fire multiple staples from a reloaded cartridge.

[0020] Continuing to refer to Figure 4, in certain embodiments, the launching member 120 may include an I-shaped beam profile in which the upper flange 126 is connected to the lower flange 124 by a vertical blade member 122. The upper flange 126 is movable within the channel of the first jaw 34, and the lower flange 124 is movable within the channel of the second jaw 32. The blade member 122 is movable within the blade channel of the reloading cartridge.

[0021] Referring to Figure 5, certain aspects of an embodiment relating to the jaw assembly of a surgical stapler are shown. A cross-section of the jaw assembly is shown longitudinally to further illustrate the operation of the operating mechanism of the surgical stapler. As shown, the elongated shaft comprises an actuating member 128 that is slidable longitudinally therein. The actuating member 128 extends to the distal end to which the firing member 120 is coupled. The reloading cartridge 50 comprises a slider 52 or wedge sled that moves parallel to the inside to advance as the longitudinal distal movement of the firing member 120 advances and fires a plurality of staples from the reloading cartridge.

[0022] Continuing to refer to Figure 5, the jaw assembly may include an upper channel 136 formed in the first jaw 34. The jaw assembly may further include a lower channel 134 formed in the second jaw 32. In the illustrated embodiment, as the firing member 120 advances longitudinally to close the jaw assembly and fire staples from the reload cartridge 50, the upper flange 126 slides within the upper channel 136 of the first jaw 34, and the lower flange 124 slides within the lower channel 134 of the second jaw 32. In the illustrated embodiment, the proximal end of the upper channel 136 includes a ramp, so that the operation of the firing member 120 across the ramp pivots the first jaw 34 into a closed configuration. The upper channel 136 further includes a channel distal to the ramp that extends substantially parallel to the lower channel 134 when the jaw is in the closed configuration.

[0023] Since the jaw assembly is intended to be reused with multiple single-use reloadable cartridges 50, it is desirable that the sliding surfaces of the launching member 120 and the lower channel 134 and upper channel 136 be configured to minimize performance degradation over multiple use cycles. With the structure clamped between the jaws, the lower surface of the upper flange 126 slides against the upper surface of the upper channel 136, and the upper surface of the lower flange 124 slides against the lower surface of the lower channel 134. That is, in certain embodiments, at least these sliding surfaces can be configured to reduce the effects of their frictional engagement. In other embodiments, it may be desirable that the first jaw 34, the second jaw 32, and all of the launching member 120 be configured to reduce the effects of their frictional engagement.

[0024] In certain embodiments, it is desirable that the jaw assembly be configured to be reused with at least 10 reload cartridges without significantly reducing performance. In certain embodiments, it may be preferable that the jaw assembly be configured to be reused with at least 12 reload cartridges without significantly reducing performance. Furthermore, it is considered desirable that the jaw assembly be configured to be operable with a desired number of reload cartridges while the first and second jaws 34, 32 apply an operating load of at least 80 pounds of compression force to the tissue clamped between them. In other embodiments, it is desirable that the jaw assembly be configured to be operable with a desired number of reload cartridges with an operating load of at least 100 pounds of compression force. In yet another embodiment, it is desirable that the jaw assembly be configured to be operable with a desired number of reload cartridges with an operating load of at least 120 pounds of compression force. In certain embodiments, the jaw assembly is configured to be operable with a desired operating load for a desired number of reload cartridges with a desired operating load while the jaws are displaced by an angular deviation of up to 1 degree from a state in which the first jaw 34 is parallel to the second jaw 32 in a closed configuration. In certain embodiments, the jaw assembly is configured to be operable for a desired number of reload cartridges with a desired operating load, with the jaws displaced by an angular deviation of up to 2 degrees from a state in which the first jaw 34 is parallel to the second jaw 32 in a closed configuration. During use, jaw misalignment may occur during stapling due to jaw deflection depending on the thickness or density of the tissue clamped between the jaws.

[0025] Generally, when two surfaces, such as the lower and upper flanges 124, 126 of a launching member and their respective lower and upper channels 134, 136, come into contact under load and slide against each other, frictional forces counteract the movement. While frictional force is proportional to the load, it ultimately does not depend on the contact area. At a microscopic level, each surface is not truly flat, but has surface irregularities or irregularities. These irregularities create localized contact points where the contact load is distributed. In such cases, the true contact area is only a small fraction of the apparent nominal area. There are several types of wear in which the coefficient of friction can gradually increase. When irregularities first come into contact, they deform elastically. However, even small loads can generate large contact stresses that, if concentrated in a small area, cause plastic deformation. Subsequently, the contact points flatten, and a joint is formed. Wear generally involves the physical removal of material from a solid. It can be divided into three categories: abrasion, adhesion, and fatigue. Abrasive wear is a slower wear process. This occurs when two surfaces rub against each other, with the harder surface scraping away at the softer surface. It often features a rough appearance and may involve the generation of fine particles. In many cases, some form of work hardening (cold working) can occur at this stage. Adhesion wear is a more aggressive form of wear that can lead to abrasion, especially in the case of metal-to-metal contact surfaces. At very localized temperatures, the peaks of opposing surface irregularities may deform and move relative to each other. If the debris is not removed, this type of wear can intensify further, leading to abrasion due to high frictional forces.

[0026] Referring to Figures 6-8, certain aspects of sliding engagement between two surfaces are shown. Force-to-distance plots are shown for exemplary combinations of sliding engagement cycles between a pair of exemplary components. Figure 6 shows force-to-distance plots for exemplary components over several sliding engagement cycles, illustrating abrasive wear and abrasion. Figure 7 shows force-to-distance plots for exemplary components over several sliding engagement cycles, illustrating multiple cycles of abrasion followed by abrasion. Figure 8 shows force-to-distance plots for exemplary components over several sliding engagement cycles, illustrating gradual abrasive wear.

[0027] Referring to Figure 6, an exemplary force-distance plot is shown for several sliding engagement cycles between exemplary sliding components. This plot illustrates the progression from at least one sliding engagement cycle with abrasive wear in the first direction 210 and abrasive wear in the second direction 212 to abrasive wear in the first direction 214 and abrasive wear in the second direction 216. When the components move in the first and second directions with abrasive wear, the frictional force between the components is relatively small and relatively constant along the distance moved. The plotted line above the x-axis indicates movement in the first direction (210, 214), while the plotted line below the x-axis indicates movement in the second direction (212, 216), opposite to the first direction. The height (or depth) of the plotted line from the x-axis represents the frictional force required to slide the components. When abrasive wear appears in the first and second directions 214, 216, the frictional force becomes very irregular and considerably larger than the frictional force that appears in the abrasive wear state. Wear is highly detrimental to the device's function because it increases the coefficient of dynamic friction by a factor greater than 1, resulting in a significant increase in the force required to actuate the device. In some cases, wear can cause the force required to actuate the device to increase to more than twice the force expected for a pair of sliding surfaces. That is, embodiments of surgical staplers having sliding components that undergo wear after several sliding engagements are considered undesirable for use with multiple reloadable cartridges because the force required to actuate the actuating mechanism becomes excessive, stressing components within the shaft and handle assemblies and making the handle assembly difficult to operate.

[0028] Referring to Figure 7, an exemplary force-to-distance plot is shown for several sliding engagement cycles between exemplary sliding components. This plot illustrates the progression from at least several sliding engagement cycles with abrasive wear in a first direction 220 and abrasive wear in a second direction 222 to abrasive wear in a second direction 224. As the components move in the first and second directions with abrasive wear, the plotted lines show multiple wear cycles in which the frictional force gradually increases until abrasion occurs, although the frictional force between the components is relatively small and relatively constant along the distance traveled. In certain embodiments, components exhibiting such wear characteristics can be used in a surgical stapler, provided that the components remain in an abrasive wear state for a number of wear cycles sufficient to allow the use of at least a desired number of reload cartridges before undergoing abrasive wear.

[0029] Referring to Figure 8, an exemplary force-to-distance plot is shown for several sliding engagement cycles between exemplary sliding components. This plot illustrates the repeated operation over multiple sliding engagement cycles with abrasive wear in a first direction 230 and abrasive wear in a second direction 232, without the components undergoing abrasive wear. As the components move in the first and second directions with abrasive wear, the frictional force between the components is relatively small, relatively constant along the distance traveled, and with minimal increase between cycles. It is desirable to include a jaw assembly for the surgical stapler so as to have wear characteristics that reduce the possibility of abrasion for repeated use with multiple reloaded cartridges.

[0030] In certain embodiments, the material selection for components of a surgical stapler that engage in sliding contact, such as jaw assemblies and firing members, can be selected based on certain priorities. For example, the material selected as the first consideration, as well as the surface preparation coating and its processing, are limited to those that satisfy biocompatibility standards for use in surgical devices that come into contact with patients. Furthermore, it is desirable that the selected materials can be joined by welding operations, thereby providing flexibility in the configuration of various aspects of the jaw design, for example, by facilitating the use of a two-piece first jaw 34 having a cover or cap welded onto the lower anvil surface, with the first jaw member forming a channel between them. Furthermore, it is desirable that the selected materials have sufficient strength and toughness properties to withstand repeated staple firing operations. Furthermore, it may be desirable that the selected materials be resistant to oxidation and corrosion. Finally, it is desirable that the selected materials can be manufactured in various processes to facilitate manufacturing efficiency, for example, including metal injection molding processes.

[0031] To achieve the desired properties, various grades of stainless steel can be selected. For example, in certain embodiments, grade 17-4 stainless steel can be selected and used for sliding components. In other embodiments, grade 420 stainless steel can be selected and used for sliding components. Grade 420 is a martensitic stainless steel, in contrast to precipitation-hardening stainless steels such as grade 17-4. Grade 420 stainless steel has a relatively higher carbon content compared to grade 17-4 stainless steel. That is, preferably, grade 420 stainless steel is relatively hardenable compared to low-carbon steel. However, martensitic stainless steels tend to have lower weldability than precipitation-hardening stainless steels because brittle martensite tends to form from the rapid cooling of the weld, which can lead to stress-induced cracking. Furthermore, the relatively high carbon content of grade 420 stainless steel may also result in relatively low corrosion resistance. Both grades 17-4 and 420 are suitable for use in metal injection molding processes.

[0032] In further embodiments regarding material selection, stainless steel of grade 13-8 or grade 455 / 465 can be selected and used. However, it should be noted that these grades of stainless steel tend to be specialty materials, and therefore may not be desirable in terms of potential cost, availability, and manufacturability concerns.

[0033] The material selection considerations indicate that metallic stainless steel is desirable for use in the jaw assemblies and launching members of surgical staplers. Therefore, further consideration is needed regarding the preparation and treatment of the properties of these components to reduce the potential for abrasion that may arise from metal-to-metal sliding engagements. Generally, materials with relatively high surface hardness may be more resistant to abrasion. Various techniques exist for achieving relatively high surface hardness in metal substrates, such as stainless steel substrates, which are being considered for use in the sliding components of surgical staplers. For example, in various embodiments, at least one of diffusion / thermochemical techniques, surface plating techniques, surface coating techniques, and applied energy techniques can be used to prepare the surface of a metal substrate for use in sliding contacts with reduced abrasion.

[0034] In diffusion or thermochemical processes, the surface layer of a metal substrate is hardened, typically at relatively high temperatures, by adding hardening species such as carbon, nitrogen, or boron. These processes can be called "surface hardening" in that they aim to produce a relatively hard case or surface layer while maintaining the toughness and ductility of the core. However, typical surface hardening techniques have yielded undesirable results for stainless steel materials, particularly precipitation-hardening stainless steels, in that they reduce the corrosion resistance of the stainless steel. Furthermore, in the case of precipitation-hardening stainless steels, surface hardening methods involving relatively high temperatures can lead to unintended annealing of the material. Moreover, when a metal substrate is formed using a metal injection molding process, the substrate may have a relatively high porosity. That is, unless there are further modifications to the surface hardening technique to control the depth of the hardened layer, the depth of the surface hardened layer may differ from the depth of a metal substrate of similarly hardened material not formed by a metal injection molding process.

[0035] However, certain surface hardening techniques can be used on stainless steel materials with little to no undesirable significant effects. For example, there is S3P (Specialty Stainless Steel Processes) offered by Bodycote plc and a relatively low-temperature diffusion surface hardening technique commercially known under the trademark KOLSTERISING. This diffusion technique can surface harden relatively low-carbon stainless steels, such as Grade 17-4 stainless steel, while minimizing the reduction in corrosion resistance and minimizing the impact on the basic strength and ductility of the metal substrate.

[0036] Another technique for generating a hardened layer involves surface modification, which corrects the grain structure of the metal substrate in the outer layer through work hardening. For example, shot peening (impacting the substrate with high-speed shots) or ion implantation (impacting the metal substrate with high-speed particles) can be used to form a hardened surface layer. Advantageously, these processes do not affect surface chemistry, i.e., they do not reduce corrosion resistance. However, if foreign matter is present in the shot (e.g., if the shot medium is reused), the foreign matter may become embedded in the metal substrate, potentially leading to localized corrosion resistance degradation. Furthermore, these surface modification processes can present manufacturing challenges because only the impacted surface is work-hardened, requiring strict control of fixtures, shot size, strength, and coverage to facilitate consistent results and reduce the possibility of substrate distortion.

[0037] In certain embodiments, surface plating, i.e., the step of introducing a thin layer of a metallic compound onto a substrate, can be used to produce desired surface hardness properties in the sliding components of a surgical stapler. Examples of the types of materials that can be used for surface plating to impart surface hardness include chromium, electroless nickel, diamond-like coatings, and ceramics. Advantageously, depending on the selected material, surface plating can be a dipping process that can be carried out at the component level with consistent surface properties. However, surface plating can affect the weldability of a component because the plating compound is present in the base material, affecting the strength of the component. Furthermore, highly hard surface plating can also be relatively brittle and tend to crack and break down into particles unnecessarily when subjected to large loads at point contact. In components of a surgical stapler, in certain examples, particularly when there is jaw misalignment or when large tissue portions are clamped between the jaws, the engagement of the flanges of the launching member may engage with each channel at virtually point contact.

[0038] In certain embodiments, the metal substrates of sliding components of a surgical stapler may have surface coatings applied to provide desirable operating characteristics. However, generally, surface coatings do not adhere to metal substrates as well as surface plating. Furthermore, similar to surface plating, surface coatings may become granular when loaded during use. That is, it is preferable to use biocompatible surface coating materials. Moreover, if the surface coating is applied before welding the material substrate, it may form part of the weld base material and reduce the strength of the welded component. Therefore, the effect of the surface coating on the weldability of the substrate can be minimized by choosing to mask the welding location or to apply the coating after the welding operation.

[0039] Various surface coatings can be applied to metal substrates to improve sliding performance. For example, in certain embodiments, lubricants such as those commercially available under the trademarks KRYTOX from Chemours Company or MOLYKOTE from Dow Corning Corporation can be applied to the sliding surfaces. In other embodiments, a dry film polytetrafluoroethylene (PTFE) coating can be applied to the sliding surfaces to enhance lubrication between them. For example, a coating commercially available from Donwell Company, Inc. as Dry Film RA coating can be applied to the sliding components of surgical instruments. PTFE dry film materials may be suitable for use in applications that come into contact with patients and can be strategically applied at the component level through a spraying process or a dipping process.

[0040] In certain embodiments, sliding performance can be improved by applying bone solder as a surface coating to function as a lubricant between sliding surfaces. Various bone solder compositions are commercially available and typically consist primarily of beeswax. Bone solder is suitable for use in patient-contact applications as it has traditionally been applied to reduce bleeding from bone surfaces during medical procedures. Desirably, bone solder is adhesive and adheres well to the applied surface. Furthermore, bone solder generally undergoes only minimal particle formation, even in the case of point-contact engagement between sliding surfaces. However, bone solder may have a relatively low melting transition temperature (which can be around 120°F for certain bone solder compositions). That is, the expected sterilization and transport temperature range must be evaluated to reduce the possibility of the applied bone solder melting and accumulating. Furthermore, since bone solder is typically applied manually to the target surface, uniform application to concave surfaces such as jaw assembly channels may require special application tools and procedures.

[0041] Referring to Figure 9A, a schematic cross-sectional view of a metal substrate surface to be used as a sliding surface for a surgical staple fastening device is shown. As mentioned above, from the standpoint of various considerations regarding material selection, stainless steel is suitable for use in sliding components of surgical staple fastening devices, such as the launching member and jaw member of the jaw assembly of a surgical stapler. However, in metal-to-metal sliding engagements, these materials can be subjected to unwanted abrasion. Therefore, it is desirable to prepare the sliding surface to withstand abrasion. In the illustrated embodiment, the component comprises a metal substrate 240 having a first strength and a first hardness. The surface layer 242 of the metal substrate 240 is hardened to a second hardness greater than the first hardness. For example, in certain embodiments, surface hardening is used to produce a surface layer 242 with a second hardness and a depth D. In some embodiments, a diffusion method is used for the surface hardening method. In certain embodiments, a low-temperature diffusion surface hardening method is used.

[0042] Continuing to refer to Figure 9A, in certain embodiments, the first surface coating layer 244 can be laminated on the metal substrate 240 and its hardened surface layer 242. For example, in some embodiments, it may be desirable to select the first surface coating to suppress metal-to-metal contact. Furthermore, since certain surface hardening methods tend to reduce the corrosion resistance of stainless steel materials, in certain embodiments, it may be desirable that the first surface coating layer contain an antioxidant.

[0043] Continuing to refer to Figure 9A, in certain embodiments, the components of the surgical stapler may further include a second surface coating layer 246 laminated on top of the first surface coating layer 244. The second surface coating layer 246 may be selected to reduce wear over multiple sliding engagement cycles. For example, in certain embodiments, a bone putty composition may be placed over the entire sliding surface to provide sliding lubrication properties for multiple reloading cycles. Advantageously, the bone putty composition can improve the sliding contact of the components of the surgical stapler, even when point contact increases due to accidental mismatches.

[0044] Continuing to refer to Figure 9A, another aspect of surface preparation for the sliding components of a surgical stapler is surface finish. In the case of sliding surfaces, it may be undesirable for the surface finish of the sliding component to be either relatively smooth (e.g., roughness less than 25 μin) or relatively rough (e.g., roughness greater than 75 μin). Very smooth sliding surfaces have a relatively large theoretical contact area and few surface irregularities. That is, these smooth surfaces may be prone to abrasion or cold welding during sliding engagement. In contrast, relatively rough surfaces may result in relatively high frictional force and particle formation because the irregularities bond together. Sliding surfaces with relatively moderate roughness (e.g., about 25 μin to 75 μin) can preferably have less abrasion and moderate frictional force compared to surfaces with relatively low and relatively high roughness. Moderate roughness can also preferably retain the surface coating when the coated surface is sliding engaged. In certain embodiments, a moderately rough surface having a surface roughness of approximately 25 μin to 75 μin can be prepared by a tumbling process.

[0045] Referring to Figure 9B, a schematic cross-sectional view of a surface of another embodiment of a metal substrate used as a sliding surface for a surgical stapling device is shown. Similar to the embodiment of the metal substrate shown above with reference to Figure 9A, the illustrated embodiment of the metal substrate comprises a core of metal substrate 240, a first coating layer 244, and a second coating layer 246. In certain embodiments, the first coating layer 244 may include a dry film, and the second coating layer may include a bone brazing layer. However, unlike the embodiment of the metal substrate in Figure 9A, as shown in Figure 9B, the metal substrate 240 does not include a surface hardened surface.

[0046] Considering the above description, there are various embodiments of material selection and surface preparation to achieve desired sliding performance in the launching member, first jaw, and second jaw without wear over a desired number of firing cycles. In one embodiment, the launching member and jaws of the jaw assembly may include Grade 17-4 stainless steel. The 17-4 stainless steel can be heat-treated to H900 conditions (corresponding to a Rockwell C hardness of about 45). The surface layer of the material can be surface-hardened to a Rockwell C hardness of about 70. For example, in some embodiments, a diffusion method such as the S3P method commercially available from Bodycote Pic can provide a hardened surface layer with a hardened layer depth of about 25-40 microns and a Rockwell C hardness of about 65-70. The launching member and jaws of the jaw assembly can be tumbling to a moderate surface roughness. For example, the components may have a surface roughness of about 25 μin to 75 μin. In one embodiment, the components have a surface roughness of about 50 μin. A first coating layer of PTFE dry film can be added. This first coating layer can prevent corrosion on the hardened surface and suppress metal-to-metal contact. The components may further include a second coating layer of a brazing composition. Advantageously, this combination of materials and process provides a jaw assembly and firing element that can withstand wear when repeatedly used in multiple single-use reloadable cartridges.

[0047] Other embodiments relating to the launching member, first jaw, and second jaw of a surgical stapler comprise grade 420 stainless steel material heat-treated to a Rockwell C hardness of approximately 55. The components can be tumbled to a moderate surface roughness. The components may include a first coating layer of PTFE dry film and a second coating layer of bone brazing composition.

[0048] Other embodiments of surgical stapler components, including at least one of the launching member, first jaw, and second jaw, are made of Grade 17-4 stainless steel. The material is heat-treated to a hardness of approximately 45 Rockwell C. For example, as described above, in certain embodiments, the material can be heat-treated up to H900 conditions. No further surface hardening is performed. The components may have a moderately rough surface finish, which can be achieved by a tumbling process. The components may include a first coating layer of PTFE dry film and a second coating layer of bone brazing composition. In certain embodiments, one or more of the launching member, first jaw, and second jaw components may be formed from Grade 17-4 stainless steel using a metal injection molding process. Certain metal injection molding processes can result in a metal substrate with a relatively high porosity compared to the corresponding machined components. Surface hardening techniques for such porous metal injection molded components may produce a hardened surface layer that is relatively deep but correspondingly relatively brittle, which may affect the bulk properties of the surface-hardened component. In other words, when the components are formed in a metal injection molding process that can produce a relatively porous metal substrate, an embodiment of the surgical stapler component without an additional surface hardening process may be desirable.

[0049] In the embodiments described above, the components are prepared so that the surface hardness of the jaws and the launching member is relatively high (from at least about 45 Rockwell C hardness to about 70 Rockwell C hardness) and substantially identical. In other embodiments, the launching member is designed to have a slightly lower surface hardness than the jaw member. For example, the launching member may have a Rockwell C hardness up to about 10 lower than the surface hardness of the jaws.

[0050] Furthermore, in the embodiments described above, surface hardening is provided by diffusion or heat treatment, but in other embodiments, shot peening or another work hardening technique may be applied to work harden the surface layer of the metal substrate of the component. This work hardened surface layer can then be covered with one or more coating layers.

[0051] Referring to Figure 10, a method for preparing a metal substrate to be used as a sliding component of a surgical stapler is shown. In certain embodiments, the method may include a step 260 of providing the metal substrate. As described above, in certain embodiments, the metal substrate may be made of stainless steel material such as Grade 17-4 stainless steel or Grade 420 stainless steel. In certain embodiments, the step of providing the metal substrate may include a step of metal injection molding the metal substrate component.

[0052] Continuing to refer to Figure 10, the method further comprises a step 262 for hardening the metal substrate to a desired hardness. In certain embodiments, the hardening step of the metal substrate may include a step of heat-treating the metal substrate. For example, in certain embodiments, the hardening step of the metal substrate includes a step of heat-treating the metal substrate to an H900 condition corresponding to a hardness of about 45 HRC. In various embodiments, the hardening step of the metal substrate may include a step of surface hardening the metal substrate by a diffusion step. In other embodiments, the hardening step of the metal substrate may include a step of work-hardening the surface layer of the metal substrate by shot peening or the like. In certain embodiments schematically shown in Figure 9B, the metal substrate is hardened to a hardness of about 45 HRC by heat treatment without further surface hardening. In other embodiments schematically shown in Figure 9A, the metal substrate is hardened by a heat treatment step, followed by surface hardening by a diffusion step or the like to achieve a relatively high surface hardness. In some embodiments, the surface layer can be hardened to about 45 HRC to 75 HRC. It may be desirable for the surface layer to be hardened to at least about 55 HRC. In certain embodiments, the surface is hardened to about 70 HRC. In certain embodiments, the metal substrates forming the launching member components for a surgical stapler are surface hardened to a first hardness, and the metal substrates forming the first and second jaws are surface hardened to a second hardness different from the first hardness. In certain embodiments, the second hardness is within a range of about 10 HRC higher than the first hardness.

[0053] Continuing to refer to Figure 10, in certain embodiments, the method further comprises a step 264 to give a moderately rough surface finish. In certain embodiments, the step to give a moderately rough surface finish may include a step of tumbling the components. In certain embodiments, the moderately rough surface finish may include a surface roughness of about 25 μin to 75 μin. In some embodiments, the surface roughness is about 50 μin.

[0054] Continuing to refer to Figure 10, in certain embodiments, the method further comprises a step 266 of applying at least one surface coating. In certain embodiments, the step of applying at least one surface coating comprises a step of applying a first surface coating and a step of applying a second surface coating. In certain embodiments, the step of applying at least one surface coating comprises a step of applying a PTFE dry film and a step of applying a brazing composition.

[0055] While this application discloses certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses of the invention and obvious modifications thereof and equivalent forms. Furthermore, various features of these inventions can be used alone or in combination with other features relating to these inventions other than those explicitly described above. That is, the scope of the present invention disclosed herein is not to be limited by the specific disclosed embodiments described above, but should be determined solely by a fair reading of the claims that follow.

Claims

1. Surgical instruments, Joe 1, and A second jaw pivotably coupled to the first jaw, An end effector equipped with, A launching member that is longitudinally slidable relative to the end effector in order to pivot the second jaw relative to the first jaw and actuate the end effector, Equipped with, At least one of the first jaw, the second jaw, and the launching member comprises a metal substrate, a dry film surface coating disposed on the metal substrate, and a brazing layer disposed on the dry film surface. A surgical instrument characterized by the following features.

2. The surgical instrument according to claim 1, characterized in that the metal substrate comprises a core and a surface hardened layer.

3. The surgical instrument according to claim 2, characterized in that the surface hardened layer is hardened to a hardness in the range of approximately 45 HRC to approximately 70 HRC.

4. The surgical instrument according to claim 2, characterized in that the surface hardened layer is formed by a diffusion process.

5. The surgical instrument according to claim 1, characterized in that the metal substrate comprises stainless steel material of grade 17-4.

6. The surgical instrument according to claim 5, characterized in that the substrate is heat-treated up to H900 conditions.

7. The surgical instrument according to claim 1, characterized in that the metal substrate comprises stainless steel material of grade 420.

8. The surgical instrument according to claim 1, characterized in that each of the first jaw, the second jaw, and the firing member comprises a metal substrate having a core and a surface hardened layer hardened to at least 55 HRC.

9. The surgical instrument according to claim 1, characterized in that the metal substrate has a surface finish roughness between approximately 25 μin and 75 μin.

10. The surgical instrument according to claim 9, characterized in that the metal substrate has a tumbling-processed surface finish.

11. It is a surgical stapler, A slender shaft extending from the proximal end to the distal end, The jaw assembly at the distal end of the elongated shaft, A cartridge support configured to accept a reloaded cartridge with multiple staples, The cartridge support and the anvil are pivotable between open and closed configurations, and A firing member that engages with the cartridge support and the anvil in the closed configuration and is slidable in the longitudinal direction for firing staples, The jaw assembly comprising, Equipped with, At least one of the anvil, the cartridge support, and the firing member comprises a surface-hardened metal substrate, a dry film surface coating disposed on the metal substrate, and a brazing layer disposed on the dry film surface. A surgical stapler characterized by the following features.

12. The surgical stapler according to claim 11, characterized in that the metal substrate is surface-hardened to at least about 55 HRC.

13. The surgical stapler according to claim 11, characterized in that the metal substrate is surface-hardened using a diffusion process.

14. The surgical stapler according to claim 11, characterized in that each of the anvil, the cartridge support, and the firing member comprises a surface-hardened metal substrate, a dry film surface coating disposed on the metal substrate, and a bone wax layer disposed on the dry film surface.

15. A method for manufacturing a surgical end effector, The steps include providing a first jaw member, a second jaw member, and a launching member, each having a metal substrate, A step of hardening at least one of the metal substrates among the first jaw member, the second jaw member, and the launching member to a first predetermined hardness, The steps include applying a dry film coating to at least one of the first jaw member, the second jaw member, and the launching member, The steps include applying a bone wax composition to at least one of the first jaw member, the second jaw member, and the launching member, A method characterized by comprising:

16. The method according to 15, characterized in that the step of providing the first jaw member, the second jaw member, and the launching member comprises the step of forming at least one of the first jaw member, the second jaw member, and the launching member from forged metal.

17. The method according to 15, characterized in that the step of providing the first jaw member, the second jaw member, and the launching member comprises the step of metal injection molding at least one of the first jaw member, the second jaw member, and the launching member.

18. The method according to 15, characterized in that the step of hardening at least one of the metal substrates among the first jaw member, the second jaw member, and the launching member comprises a step of surface hardening the metal substrate using a diffusion step.

19. The method according to 15, characterized in that the step of curing at least one of the first jaw member, the second jaw member, and the launching member of the metal substrate comprises a step of curing the metal substrate using a shot peening process.

20. The method according to 15, characterized in that the first predetermined hardness is at least about 55 HRC.

21. The method according to 20, characterized in that the step of hardening the metal substrate of at least one of the first jaw member, the second jaw member, and the launching member comprises a step of hardening all of the metal substrates of the first jaw member, the second jaw member, and the launching member to a first predetermined hardness.

22. The method according to 20, further comprising the step of hardening one of the metal substrates among the first jaw member, the second jaw member, and the launching member to a second predetermined hardness different from the first predetermined hardness.

23. The launching member is hardened to the first predetermined hardness, and the first jaw member and the second jaw member are hardened to the second predetermined hardness. The second predetermined hardness is less than approximately 10 HRC higher than the first predetermined hardness. The method according to the feature of 22.

24. The method according to 15, further comprising the step of tumbling at least one of the metal substrates among the first jaw member, the second jaw member, and the launching member before adding the dry film.

Images