Suture material and surgical suture kit

Abstract

This invention refers to surgical instruments, wound suturing devices. This invention is aimed to create a durable, non-stretchable, atraumatic suture that provides a retention effect due to the ingrowth of surrounding tissues into the suture, delivery of medicines, and practicability in various surgical applications. The task set in suture material, which represents a fiber intended for connection with a surgical needle and containing a core and a sheath, wherein the core material differs from the sheath material, is solved by that the core is made of at least one thread of biocompatible metal with an anti-slip arrangement, and the sheath is made of porous polytetrafluoroethylene, wherein porous polytetrafluoroethylene represents a porous three-dimensional structure containing open through pores and dead-end pores, the dead-end pores are evenly distributed over the inner surfaces of the open through pores and are connected to the inner surface of the open through pores.

Description

[0001] SUTURE MATERIAL AND SURGICAL SUTURE KIT

[0002] This invention refers to surgical instruments, wound suturing devices.

[0003] Wound closure devices, such as sutures, staples and rivets, are widely used in superficial and deep surgical procedures in humans and animals to close wounds, repair traumatic injuries or defects, connect tissues (bringing together torn tissues, closing anatomical cavities, fixing one or multiple layers of tissue, anastomosis between two hollow / luminal structures, closure of tissue, attachment or reconnection of tissue at the appropriate anatomical location), to attach foreign elements to tissue (fixation of medical implants, devices, prostheses and other functional or supporting devices), as well as for the reposition of tissues with new anatomical localization (restoration, tissue elevation, tissue grafting and related procedures and many other techniques).

[0004] Sutures are often used as wound closure devices. A suture typically consists of a fibrous ligature attached to a sharp-tipped needle. Sutures can be made from a wide variety of materials, including bioabsorbable (i.e., completely biodegradable in the body over time) or nonabsorbable (permanent, non-degradable) materials. Absorbable sutures have proven to be particularly useful in cases where suture removal might compromise tissue repair and where suture support is unnecessary after healing, e.g. in uncomplicated skin wounds. Nonabsorbable (non- degradable) sutures are used in situations where healing takes a long time, and where a wound requires physical support with suture for an extended period of time (e.g., deep tissue repair, high tension wounds, a variety of orthopedic treatments, and some types of surgical anastomoses). In addition, a wide variety of surgical needles are used in medical practice. The needle shape and size, as well as its tip configuration, are generally selected depending on particular application.

[0005] Given the particular importance of sutures in surgery, a wide range of modifications are applied in medical practice, differing in properties (synthetic absorbable, natural absorbable, nonabsorbable, natural nonabsorbable [https: / / footberg.by / , 2023] and in design.

[0006] A well-known metal suture design [RU173623U, 04 / 09 / 2017] is a titanium thread with a primer coating system based on poly conjugated polymers.

[0007] Another well-known metal suture design [RU2014144878, 10 / 06 / 2016] features a titanium thread coated with porous titanium nickelide.

[0008] The known metal suture materials demonstrate certain disadvantages, i.e. limited applications (inapplicable for suturing soft tissues due to cutting with metal suture) and infeasibility of biologically active coatings.

[0009] A known metal suture [CN 108607144, 28 / 05 / 2018] is a woven thread made of pure magnesium or magnesium alloy with porous ceramic layer on each thread surface. This suture accommodates no multidirectional notches to ensure strong fixation of the thread in tissues (in particular, in muscle tissue). When placed e.g. in the pelvic area without proper fixation with notches, the suture migrates and comes out when the patient moves. This causes great discomfort for the patient. Also, suture migration is always accompanied by inflammation and suppuration.

[0010] A known suture material is a multifilament core made of synthetic fibers with a multifilament braid of synthetic fibers [EA 025052, 30 / 11 / 2016], Another known suture [US9,98,6999B2, 05 / 06 / 2018] features a colored polytetrafluoroethylene (further - PTFE) monofilament. Tensile strength and visual recognition are important properties of the suture. Although conventional approaches for making expanded PTFE sutures may provide sufficient handling and abrasion resistance, Applicants identified that the conventional approaches may provide low tensile strength and may pose difficulty distinguishing the natural white color of PTFE against light or white backgrounds. In turn, Applicants identified improvements to suture tensile strength in combination with pigment additives that could improve the marketability of sutures so produced.

[0011] Multi-step process for forming a fiber, etching the fiber, and then dyeing the fiber may be complex and expensive.

[0012] One more suture design [WO2014 / 1 16780A1, 31 / 07 / 2014] represents an ePTFE monofilament with sections of different diameters. A modification of the described technique to implant the known PTFE suture in sub-right ventricular tissue to help stabilize the suture’s position is one potential option, but this may create a possibility of erosion of the sub-right ventricular tissue contacted by the implanted known PTFE suture. Care should be taken to avoid jerking motions that can tear the seam. Uneven tension can result in an unreliable knot.

[0013] When using a conventional suture design, a surgical needle is passed through the desired tissue on one side of the wound and then through the other side of the wound. The suture then forms a “loop” that ends with a knot in the suture material to hold the wound closed.

[0014] Tying knots is time-consuming and causes a number of complications, including but not limited to: (i) protrusion (a condition where the suture (usually the knot) is pushed through the skin after the wound has been closed), (ii) infection (bacteria are able to attach and proliferate in the spaces formed by the knot), (iii) mass accumulation (a significant amount of suture material entering the knot remains in the wound), (iv) slippage (knots may slip or become untied), (v) irritation (the knot is a foreign body in the wound). The suture loops used to create the knot can cause ischemia (knots create tissue pressure points to restrict regional blood flow) and increase the risk of surgical wound dehiscence and rupture. Tying knots is a rather labor-intensive process. It can take up a significant portion of time spent closing a surgical wound. Extra time for manipulations is dangerous for the patient’s health (complications may intensify as the time spent under anesthesia increases).

[0015] Well-known self-retaining sutures having barbs are described in earlier publications, e.g., [US5,374,268 A, 20 / 12 / 1994], where the suture design features barb-like protruding fastening elements. Surgical suture having barb-like lateral elements is described in [US5,584,859 A, 17 / 12 / 1996] and [US6,264,675B1, 24 / 07 / 2001]. However, the well-known sutures for continuous subcutaneous and intradermal suturing of wound edges prove to have some negative features that do not allow these manipulations to be performed efficiently: the suture devices proposed in US patents are so bulky that it makes impossible to apply continuous sutures and make scars unnoticeable.

[0016] The nearest Prior Art reference is [RU2608237 C2, 17 / 01 / 2017] where the suture material is revealed. The suture material is a fiber intended for connection with a surgical needle and contains a core and a sheath, and the core material differs from the sheath material. The sheath is made with barbs which, when the suture is applied, cut into the surrounding tissue and prevent the suture material from moving backwards.

[0017] The main disadvantage of all self-retaining suture materials is that the barbs injure surrounding tissues. During surgical manipulations, the ability to deliver a drug to the surgery site serves an important advantage. Effective wound healing practice requires that the drug be delivered to the desired location in the proper concentration.

[0018] This invention is aimed to create a durable, non-stretchable, atraumatic suture that provides a retention effect due to the ingrowth of surrounding tissues into the suture, delivery of medicines, and practicability in various surgical applications.

[0019] The task set in suture material, which represents a fiber intended for connection with a surgical needle and containing a core and a sheath, wherein the core material differs from the sheath material, is solved by that the core is made of at least one thread of biocompatible metal with an anti-slip arrangement, and the sheath is made of porous polytetrafluoroethylene, wherein porous polytetrafluoroethylene represents a porous three-dimensional structure containing open through pores and dead-end pores, the dead-end pores are evenly distributed over the inner surfaces of the open through pores and are connected to the inner surface of the open through pores.

[0020] Preferably, the suture integrates a titanium dioxide layer between the core and sheath.

[0021] The sizes of open through pores and dead-end pores are preferably selected in the range of 150-300 pm and correspond to the size of the cells in the tissue to be sutured.

[0022] The drug may be distributed isotropically or anisotropically throughout the suture sheath.

[0023] Preferably, the core is to be made of biocompatible metal similar to that of the surgical needle the suture is intended to be connected to. The anti-slip arrangement may comprise of at least one knot with the thread of biocompatible metal being tied to, or the core may accommodate more than one strand of biocompatible metal woven together to form the anti-slip arrangement.

[0024] The task set is further solved in surgical suture kit, containing the claimed suture material and a sleeve assembly of at least three adjacent cylinders, each with a through axial cavity of at least the diameter of the suture, wherein the thread of the suture material is placed inside the axial cavity of one of the cylinders and all cylinders are designed with the option of inelastic reduction of their diameters.

[0025] The aforesaid sleeve cylinders can be made twisted or braided from the claimed suture material.

[0026] The non-restrictive examples of the claimed suture and kit invention are explained in detail with reference to the following non-restrictive drawings, where:

[0027] Fig. 1 shows a schematic general view of the claimed suture system;

[0028] Fig. 2 shows a microphotographic view of the claimed suture at x40 magnification;

[0029] Fig. 3 provides a schematic example of connecting the claimed suture with a surgical needle;

[0030] Fig. 4 gives a schematic example of the claimed surgical suture kit in the starting configuration.

[0031] Fig. 5 gives a schematic example of the claimed surgical suture kit in an in- use configuration.

[0032] Fig. 6 provides a schematic sectional view of the sleeve assembly as part of the claimed surgical suture kit (magnification).

[0033] The claimed suture material represents a fiber (1) containing a core made of at least one thread (2) of biocompatible metal with titanium dioxide layer (3) and having a knot-like anti-slip arrangement (4) thread (2) being tied to. The core can be made of several threads of biocompatible metal woven together to form the anti-slip arrangement (not shown in the drawings). Fiber (1) contains a sheath (5) made of porous polytetrafluoroethylene (further - PTFE), representing a porous three-dimensional structure containing open through pores and dead-end pores, evenly distributed over and passing to the inner surface of the open through pores.

[0034] Thread (2) for the claimed suture core is selected to have the same diameter for all standard sizes of the claimed suture; the diameter of thread (2) should not exceed 100 pm, preferably 20 pm. Knots (4) are tied on thread (2) by use of a knitting machine according to a predetermined pattern. Knots can be made along the entire length of the thread (2) section or, to ensure that the suture material can be tied, only on specific fraction of the specified section. It is also possible to make the claimed suture core by weaving two or more threads to form a three- dimensional structure for anti-slip function (not shown in the drawings). Preferably, the finished core is coated with titanium dioxide layer 3.

[0035] Porous PTFE structure is made, for example, by the method described in [Belarus Patent No. 10325, publ. 02 / 28 / 2008] by mixing starter (PTFE) granules with blowing agent (table salt) granules, pressing the resulting mixture, washing out the table salt from the resulting porous workpiece and its subsequent sintering. The complex structure of the pores is ensured, in this case, by the splintered shape of the porogen granules. The sizes of dead-end pores are determined by the grain sizes of the blowing agent fine fraction, and the sizes of open pores are determined by the sizes of the blowing agent large fraction grains. The sheath thickness is selected to accommodate the required thickness of the manufactured suture material according to Table 1 below.

[0036] The claimed suture can be manufactured, for example, by extrusion. The mixture of PTFE and table salt granules prepared as described above is applied to a ready thread (2) with knots (4), with titanium dioxide layer (3) plated. Next, the workpiece is compressed (pressed), table salt is washed out in a stream of water and sintered, forming a sheath (5) of porous PTFE (see Fig. 2). The diameter of the finished suture material should match the dimensions as referenced, e.g., in the most commonly used US Pharmacopeia (USP), or European Pharmacopeia (EP):

[0037] Table 1

[0038] Table 1 continued

[0039] The most common applications provide for the following suture thicknesses:

[0040] - skin suture on the trunk and limbs - 3 / 0; - skin suture on the face / fingers / children - 5 / 0;

[0041] - subcutaneous suture - 3 / 0;

[0042] - vascular ligatures - 2 / 0;

[0043] - muscle suture - 0 to 2;

[0044] - fascia suture - 1 to 3; - vascular suture -5 / 0 to 7 / 0;

[0045] - nerve suture - 8 / 0 to 10 / 0

[0046] To connect to surgical needle (6), a small thread (2) end section of fiber (1) is stripped from sheath (5) and inserted into groove (7) of needle (6), and then secured by any known method.

[0047] Made of the same biocompatible metal, e.g., titanium or stainless steel, the thread (2) / needle (6) system is easier to connect, for example, by spot welding, and also avoids the potential differences at metal-to-metal interface and accompanying corrosion.

[0048] It should be noted that polytetrafluoroethylene is characterized by “creeping” (ref.: Encyclopedia of Polymers, Vol. 3. Soviet Encyclopedia Publishing House, M., 1998, p. 645) or “pseudofluidity” behavior (ref.: A.V. Goryainova et al. Fluoroplastics in mechanical engineering. M., 1971, p. 15); recrystallization process develops at room temperature even under minor mechanical loads, which results in deformations. Thus, knots tied with the claimed suture material may become loose over time.

[0049] Considering the said property, a surgical suture kit is proposed, which comprises the claimed suture material in the form of thread ( 1 ) (see Fig. 1 -3) with the surgical needle (6) and sleeve assembly (8) (see Fig. 4-6). The sleeve assembly (8) accommodates three adjacent cylinders (9), (10) and (11) (Fig. 6), each with a through axial cavity of at least the diameter of the suture. In this example, cylinders (9), (10) and (11) are arranged in parallel and connected solidly lengthwise. Thread (1) of the suture material is placed inside the axial cavity of one of the aforesaid cylinders, in this example, in cylinder (10). To avoid damage to thread (1), the ends of cylinders (9), (10), (11) are made rounded. In the starting configuration sleeve assembly (8) (Fig. 4) is positioned close to the available end of suture thread (1) equipped with needle (6).

[0050] The cylinders are made twisted or braided from the claimed suture material, thus enabling the inelastic reduction of their diameters.

[0051] A medicinal substance may be sprayed along the suture isotropically or anisotropically.

[0052] The medicinal substance (drug) features a chemical substance that can penetrate the body and change its physiology. Drugs include, e.g., synthetic and natural toxins, biologically active substances, and known pharmaceuticals, including those listed in [2010 Physicians’ Desk Reference® (PDR® 2009)].

[0053] The drug is applied to suture material so that the suture is bound to the drug during implantation into the patient’s tissue and releases the drug into the patient’s tissue after implantation.

[0054] The drug can be bound to the suture by a variety of methods. The inventive suture material should preferably be impregnated with drug after porous PTFE sheath (5) complete formation on thread (2), e.g., by spraying a drug film or by immersing the suture in a drug solution.

[0055] Prepared suture sections with needles attached and / or surgical suture kits are sterilized and placed in sterile packaging.

[0056] The claimed suture is used by applying well-known, traditional techniques to close wounds, repair traumatic injuries or defects, connect tissues (bringing together tom tissues, closing anatomical cavities, fixing one or multiple layers of tissue, anastomosis between two hollow / luminal structures, closure of tissue, attachment or reconnection of tissue at the appropriate anatomical location), to attach foreign elements to tissue (fixation of medical implants, devices, prostheses and other functional or supporting devices), as well as for the reposition of tissues with new anatomical localization (restoration, tissue elevation, tissue grafting and related procedures and many other techniques). Available ends of fiber (1) of the claimed suture are usually tied with a knot.

[0057] When suturing tissues using the claimed surgical suture kit, sleeve assembly (8) slides along the thread (1) to prepare in the in-use configuration (Fig. 5). Needle (6) is inserted inside cylinder (9) of sleeve assembly (8), the available end of thread (1) is pulled to stop. Then, needle (6) is inserted to the in a counter direction into cylinder (11) of sleeve assembly (7), the available end of fiber (1) is pulled to stop, and the entire sleeve assembly (7) is compressed to fix the connection.

[0058] Since the claimed suture belongs to non-absorbable devices, it remains in contact with the surrounding tissues of the patient’s body, and, thanks to the specific pore structure of porous PTFE sheath (5), the tissue cells trend to actively grow into the porous PTFE layer and consolidate. However, when tissue cells reach the metal thread (2), in some cases, a rejection reaction is possible at the metal-cell boundary of the body tissue, unless the titanium dioxide layer is applied. The titanium dioxide layer avoids such direct contact, and, as a result, no rejection reaction and possible associated complications develop.

[0059] The applicant studied the behavior of various body tissues in contact with porous PTFE.

[0060] Thus, the behavior of soft gum tissue in contact with porous PTFE was investigated in WO 2013 / 029142, where the outcome of experimental dental implantation of porous PTFE ring around the tooth neck was detailed on page 9 as follows.

[0061] Three dental implants with porous PTFE ring surrounding the implant neck were subjected to macroscopic and microscopic examination. During the removal thereof, a fragment of soft tissue, fixed firmly in the area of the polytetrafluoroethylene ring, was removed together with the implant. The volume of the tissues fused with the ring, varied a wide range. In one of the samples studied the contours of the ring were visible, in the other sample the thickness of the adjacent tissue 10 exceeded the thickness of the ring about twofold.

[0062] Histological examination established that the dense fibrous connective tissue interacts with ring around the neck of the tooth. It adjoins the surface of the ring and advances into the pores of the material of which the ring is made. The bundles of collagen fibers, as well as a large number of fibroblasts are clearly seen at the large magnification on the histological preparations stained with hematoxylin and eosin. The presence of the fragments of multi layered non-squamous epithelium interacting with the polytetrafluoroethylene insertion of the dental implant was revealed in the investigated samples.

[0063] The behavior of nervous tissue in contact with porous PTFE was reported in WO 2018 / 227264, where the outcome of experimental porous PTFE implantation of inside the transsection of the rat spinal cord area was detailed on pages 7-9 as follows.

[0064] Based on the histological (stain with haematoxylin and eosin), neurohistological (Nissl stain) and histochemical (detection of ACE, LDG and SDG activity) examinations, one may conclude that:

[0065] • The rearrangement of the structure of spinal cord area under test was observed in the places of PTFE placement. The nerve cell appendages grew into the implant pores throughout the volume of the PTFE implanted, proving the restored nerve impulse conduction in the transsection region. No hypertrophy of the connective-tissue (collagen) scar was noted.

[0066] • The spinal cord neuron cell appendages regenerate actively in the region of the spinal cord injury, into the pore of the implanted PTFE throughout the volume in the side of the adjoining intact regions of the spinal cord.

[0067] • The neuron cell appendages regenerating in the PTFE implanted in the injured region of the spinal cord, restore its functional activity, as showed by the significant increase of the activity values of the energy metabolism enzymes - LDG and SDG in regenerating nerve cell appendages

[0068] • No significant differences were found in the percentage of viable cells in the dog spinal cord samples without the half-transsection of the spinal cord or after the PTFE implant placement in the region of the experimental injury.

[0069] • No significant difference was detected in the course of the calculation of histochemical values of CD90 (stem cell marker) expression in the spinal cord samples from the intact dog and the dog after the PTFE implant placement in the region of the experimental injury.

[0070] • The section of the rat spinal cord area after the half-transsection and destruction of the thoracic vertebra (Ti l) without the implant placement was visualized. Treatment with haematoxylin-eosin (X400). Along the edge of the scar tissue one can observe the formation of the glial capsule (intensive red colour (black colour - in the drawing), course connective-tissue (collagen) scar) which wall is formed by glial cells, predominantly, astrocytes, locating in the form of the multilayer shaft. The glial cells, as detected in adjoining regions of the spinal cord, undergo dystrophic changes. Hemodynamic disorders are found in the adjoining areas of the spinal cord, they are the result of the necrobiotic changes in blood vessel walls, entry of the blood liquid fraction to the circumvascular space and development of pericapillary oedema. Vacuolization and cytoplasm swelling, destruction of some cells (white hollows) are noted. A particular attention should be paid to the applicant’s study reported in WO 2020 / 206523, which represented dog heart muscle tissue behavior in contact with porous PTFE surrounding a metal structure, where the outcome of experimental implantation of a Clip Device for Left Atrial Appendage (LAA) Isolation was detailed on page 8 as follows.

[0071] Reference to the histological and histochemical studies of the atrial appendage with an implanted clip covered with porous PTFE, it can be concluded that:

[0072] - LAA myocardial cells (cardiomyocytes, connective tissue, vessels) actively germinate into porous PTFE, as evidenced by hematoxylin-eosin staining of numerous muscle cells, vessels and connective tissue in the pores of PTFE material covering the clip device;

[0073] - LAA myocardium tissue, which germinates into porous PTFE, is functionally consistent, as evidenced by the energy metabolism enzymes identified in cardiomyocytes, i.e. lactate dehydrogenase and succinate dehydrogenase, being the indication of metabolic activity. Despite the fact that the enzyme activity is slightly lower compared to that in the reference sample (intact LAA tissue), it can be assumed that, for a longer period of LAA tissue clamping, cardiomyocytes germinating in porous PTFE will show more prominent metabolic activity due to structural and adaptive rearrangements caused by the presence of synthetic material;

[0074] - LAA muscle tissue that grows into porous PTFE retains its cholinergic innervation, as evidenced by thin AChE-positive nerve fibers detected, which are visualized even in deeper layers of porous PTFE.

[0075] The latter study made evident that surrounding tissue grew into porous PTFE, even if applied as a layer to a metal substrate. Thus, being a non-absorbable device to remain in the patient’s body for a long time, the claimed suture will also be subject to the stitched tissue ingrowth, which ensures the strength of the resulting suture. The claimed suture design provides for extra strength due to metal core (thread (2), thus ensuring the suture’s additional advantages:

[0076] - it becomes possible to use threads of smaller diameter. The stronger the thread material, the smaller the thread diameter is needed and the less traumatic the suturing process will be to tissues. The metal core enhances the strength of the knot. Knot strength is the ability of the thread to hold the knot. The stronger the knots, the fewer knots are needed to suture the wound. The fewer knots are placed on the wound, the better, since the sutured tissues are injured less.

[0077] - the risk of unreliable knot is reduced due to uniform thread tension. The metal core and the applied PTFE surface layer make it possible to obtain a universal thread that will allow this material to be used in almost all surgery applications.

[0078] Traditionally, PTFE suture material is used in dental surgery, implant surgery, bone graft surgery, plastic surgery, subcutaneous closure, orthopedics, arthroscopic tendon repair, cardiac surgery, valve repair, pediatric surgery, gynecology.

[0079] Metal suture material is used to close the sternum during heart surgery and orthopedic surgery.

[0080] The claimed suture can be used for all surgery applications as described above.

[0081] Thus, the invention device provides a durable, non-stretching, atraumatic suture material, featuring a retention effect due to the ingrowth of surrounding tissues into the suture material, delivery of medicinal substances, and practicability in various surgery applications.

Claims

The Claims1. Suture material, which represents a fiber intended for connection with a surgical needle and containing a core and a sheath, wherein the core material differs from the sheath material, characterized in that the core is made of at least one thread of biocompatible metal with an anti-slip arrangement, and the sheath is made of porous polytetrafluoroethylene, wherein porous polytetrafluoroethylene represents a porous three-dimensional structure containing open through pores and dead-end pores, the dead-end pores are evenly distributed over the inner surfaces of the open through pores and are connected to the inner surface of the open through pores.

2. Suture of claim 1, characterized in that the suture is equipped with a titanium dioxide layer between the core and sheath.

3. Suture of claim 1 , characterized in that the sizes of open through pores and dead-end pores are selected in the range of 150-300 pm and correspond to the size of the cells in the tissue to be sutured.

4. Suture of claim 1, characterized in that the drug is distributed isotropically or anisotropically throughout the suture sheath.

5. Suture of claim 1 , characterized in that the core is made of biocompatible metal similar to that of the surgical needle the suture is intended to be connected to.

6. Suture of claim 1, characterized in that the anti-slip arrangement comprises of at least one knot with the thread of biocompatible metal being tied to.

7. Suture of claim 1, characterized in that the core accommodates more than one thread of biocompatible metal woven together to form the anti-slip arrangement.

8. Surgical suture kit containing the claimed suture material and a sleeve assembly of at least three adjacent cylinders, each with a through axial cavity of at least diameter of the suture, wherein the thread of the suture material is placed inside the axial cavity of one of the cylinders, and all cylinders are designed with the option of inelastic reduction of their diameters.

9. Surgical suture kit of claim 8, characterized in that the aforesaid sleeve cylinders are made twisted or braided from the claimed suture material specified in claims 1 to 7.

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