Patent Application
20110125188
The present invention relates generally to self-retaining systems for surgical procedures, methods of manufacturing self-retaining systems for surgical procedures, and uses thereof.
Wound closure devices such as sutures, staples and tacks have been widely used in superficial and deep surgical procedures in humans and animals for closing wounds, repairing traumatic injuries or defects, joining tissues together (bringing severed tissues into approximation, closing an anatomical space, affixing single or multiple tissue layers together, creating an anastomosis between two hollow/luminal structures, adjoining tissues, attaching or reattaching tissues to their proper anatomical location), attaching foreign elements to tissues (affixing medical implants, devices, prostheses and other functional or supportive devices), and for repositioning tissues to new anatomical locations (repairs, tissue elevations, tissue grafting and related procedures) to name but a few examples.
Sutures are often used as wound closure devices. Sutures typically consist of a filamentous suture thread attached to a needle with a sharp point. Suture threads can be made from a wide variety of materials including bioabsorbable (i.e., that break down completely in the body over time), or non-absorbable (permanent; non-degradable) materials. Absorbable sutures have been found to be particularly useful in situations where suture removal might jeopardize the repair or where the natural healing process renders the support provided by the suture material unnecessary after wound healing has been completed; as in, for example, completing an uncomplicated skin closure. Non-degradable (non-absorbable) sutures are used in wounds where healing may be expected to be protracted or where the suture material is needed to provide physical support to the wound for long periods of time; as in, for example, deep tissue repairs, high tension wounds, many orthopedic repairs and some types of surgical anastomosis. Also, a wide variety of surgical needles are available, and the shape, and size of the needle body and the configuration of the needle tip is typically selected based upon the needs of the particular application.
To use an ordinary suture, the suture needle is advanced through the desired tissue on one side of the wound and then through the adjacent side of the wound. The suture is then formed into a “loop” which is completed by tying a knot in the suture to hold the wound closed. Knot tying takes time and causes a range of complications, including, but not limited to (i) spitting (a condition where the suture, usually a knot, pushes through the skin after a subcutaneous closure), (ii) infection (bacteria are often able to attach and grow in the spaces created by a knot), (iii) bulk/mass (a significant amount of suture material left in a wound is the portion that comprises the knot), (iv) slippage (knots can slip or come untied), and (v) irritation (knots serve as a bulk “foreign body” in a wound). Suture loops associated with knot tying may lead to ischemia (knots can create tension points that can strangulate tissue and limit blood flow to the region) and increased risk of dehiscence or rupture at the surgical wound. Knot tying is also labor intensive and can comprise a significant percentage of the time spent closing a surgical wound. Additional operative procedure time is not only bad for the patient (complication rates rise with time spent under anesthesia), but it also adds to the overall cost of the operation (many surgical procedures are estimated to cost between $15 and $30 per minute of operating time).
Self-retaining sutures (including barbed sutures) differ from conventional sutures in that self-retaining sutures possess numerous tissue retainers (such as barbs) which anchor the self-retaining suture into the tissue following deployment and resist movement of the suture in a direction opposite to that in which the retainers face, thereby eliminating the need to tie knots to affix adjacent tissues together (a “knotless” closure). Knotless tissue-approximating devices having barbs have been previously described in, for example, U.S. Pat. No. 5,374,268, disclosing armed anchors having barb-like projections, while suture assemblies having barbed lateral members have been described in U.S. Pat. Nos. 5,584,859 and 6,264,675. Sutures having a plurality of barbs positioned along a greater portion of the suture are described in U.S. Pat. No. 5,931,855, which discloses a unidirectional barbed suture, and U.S. Pat. No. 6,241,747, which discloses a bidirectional barbed suture. Methods and apparatus for forming barbs on sutures have been described in, for example, U.S. Pat. No. 6,848,152. Self-retaining systems for wound closure also result in better approximation of the wound edges, evenly distribute the tension along the length of the wound (reducing areas of tension that can break or lead to ischemia), decrease the bulk of suture material remaining in the wound (by eliminating knots) and reduce spitting (the extrusion of suture material—typically knots—through the surface of the skin. All of these features are thought to reduce scarring, improve cosmesis, and increase wound strength relative to wound closures using plain sutures or staples. Thus, self-retaining sutures, because such sutures avoid knot tying, allow patients to experience an improved clinical outcome, and also save time and costs associated with extended surgeries and follow-up treatments. It is noted that all patents, patent applications and patent publications identified throughout are incorporated herein by reference in their entirety.
The ability of self-retaining sutures to anchor and hold tissues in place even in the absence of tension applied to the suture by a knot is a feature that also provides superiority over plain sutures. When closing a wound that is under tension, this advantage manifests itself in several ways: (i) self-retaining sutures have a multiplicity of retainers which can dissipate tension along the entire length of the suture (providing hundreds of “anchor” points, this produces a superior cosmetic result and lessens the chance that the suture will “slip” or pull through) as opposed to knotted interrupted sutures which concentrate the tension at discrete points; (ii) complicated wound geometries can be closed (circles, arcs, jagged edges) in a uniform manner with more precision and accuracy than can be achieved with interrupted sutures; (iii) self-retaining sutures eliminate the need for a “third hand” which is often required for maintaining tension across the wound during traditional suturing and knot tying (to prevent “slippage” when tension is momentarily released during tying); (iv) self-retaining sutures are superior in procedures where knot tying is technically difficult, such as in deep wounds or laparoscopic/endoscopic procedures; and (v) self-retaining sutures can be used to approximate and hold the wound prior to definitive closure. As a result, self-retaining sutures provide easier handling in anatomically tight or deep places (such as the pelvis, abdomen and thorax) and make it easier to approximate tissues in laparoscopic/endoscopic and minimally invasive procedures; all without having to secure the closure via a knot. Greater accuracy allows self-retaining sutures to be used for more complex closures (such as those with diameter mismatches, larger defects or purse string suturing) than can be accomplished with plain sutures.
A self-retaining suture may be unidirectional, having one or more retainers oriented in one direction along the length of the suture thread; or bidirectional, typically having one or more retainers oriented in one direction along a portion of the thread, followed by one or more retainers oriented in another (often opposite) direction over a different portion of the thread (as described with barbed retainers in U.S. Pat. Nos. 5,931,855 and 6,241,747). Although any number of sequential or intermittent configurations of retainers are possible, a common form of bidirectional self-retaining suture involves a needle at one end of a suture thread which has barbs having tips projecting “away” from the needle until the transition point (often the midpoint) of the suture is reached; at the transition point the configuration of barbs reverses itself about 180° (such that the barbs are now facing in the opposite direction) along the remaining length of the suture thread before attaching to a second needle at the opposite end (with the result that the barbs on this portion of the suture also have tips projecting “away” from the nearest needle). Projecting “away” from the needle means that the tip of the barb is further away from the needle and the portion of suture comprising the barb may be pulled more easily through tissue in the direction of the needle than in the opposite direction. Put another way, the barbs on both “halves” of a typical bidirectional self-retaining suture have tips that point towards the middle, with a transition segment (lacking barbs) interspersed between them, and with a needle attached to either end.
Despite the multitude of advantages of unidirectional and bidirectional self-retaining sutures, there remains a need to improve upon the design of the suture such that a variety of common limitations can be eliminated. Specifically, several problems common to existing self-retaining sutures can be addressed by the embodiments of this invention, including, but not limited to: (i) retainers or barbs that are fragile and break or too flexible and bend back, or do not stand proud due to an insufficient ability of the material to plastically deform and as such do not properly engage when deployed in tissue; (ii) inadequate “hold” provided by the retainers for some surgical procedures; resulting in retainers or barbs do not sufficiently anchor in the surrounding tissue and “pull through;” (iii) insufficient contact between the retainers and the surrounding tissue (often occurring when the thread diameter is too small relative to the diameter of the hole created by a larger needle; this limits the ability of the retainers to contact and “grip” the surrounding tissue); (iv) breakage of the self-retaining suture during tensioning and wound approximation; and (v) rotation and slippage of the retainers after deployment. Furthermore, the creation and or deployment of retainer features of self-retaining sutures may be difficult to achieve.
In accordance with the foregoing background and the limitations of the prior art, the present invention provides, shape-memory self-retaining sutures which have enhanced ability to anchor into the surrounding tissue, enhanced tissue holding capabilities, enhanced maximum load, and enhanced clinical performance.
In accordance with another aspect, the present invention provides methods for making shape-memory self-retaining sutures which have enhanced ability to anchor into the surrounding tissue, enhanced tissue holding capabilities, enhanced maximum load, and enhanced clinical performance.
In accordance with another aspect, the present invention provides procedures utilizing shape-memory self-retaining sutures which have enhanced ability to anchor into the surrounding tissue, enhanced tissue holding capabilities, enhanced maximum load, and enhanced clinical performance.
In accordance with another aspect, the present invention provides self-retaining sutures comprising a filament including at least one shape-memory material which enhances the creation, elevation and deployment of the retainers and/or the suture.
In accordance with another aspect, the present invention provides self-retaining sutures comprising retainers which have shape-memory properties which permit controllable elevation and deployment of the retainers.
In accordance with one aspect, there is provided a self-retaining suture including a filament; a plurality of retainers disposed on the filament, each retainer having a retainer base engaging the filament; and a first shape-memory material. The self-retaining suture has a first form and a second form, and a transition in the suture from the first form to the second form is effectuated by a primary transition stimulus. In various embodiments, either the first form and/or the second form may include elevated retainers. Similarly, in various embodiments, either the first form and/or the second form may include an increase in the filament length. In certain embodiments, at least one of the filament and the retainers may include the shape-memory material. In certain embodiments, the primary transition stimulus may be at least one of the following: a selected electric field, a selected magnetic field, electromagnetic radiation of a selected magnitude, a selected temperature, a selected pressure, a selected pH, a selected chemical environment, or a selected solvation environment. In further embodiments, the suture may include a third form, wherein a transition in the suture from the second form to the third form is effectuated by a secondary transition stimulus. In some of the embodiments in which the suture includes a third form, the third form comprises elevated retainers and/or an increased filament length. In addition, in some of the embodiments including a third suture form, the secondary transition stimulus may be one or more of the following: a selected electric field, a selected magnetic field, electromagnetic radiation of a selected magnitude, a selected temperature, a selected pressure, a selected pH, a selected chemical environment, or a selected solvation environment. In certain embodiments, the shape-memory material may be selected from the class comprised of polymers, thermoplastics, metal alloys, hydrogels and ceramics. In particular embodiments, the shape-memory material may be a metal alloy, and in some of those embodiments, the metal alloy may be a nickel-titanium alloy. In some embodiments, the suture may comprise more than one material, and one of those materials may be the first shape-memory material. In some embodiments, the retainers may include at least in part the first shape-memory material. In some embodiments, in which the suture comprises more than one material, another of the materials may be a second shape-memory material. In some such embodiments, the retainers may include at least in part the second shape-memory material. In addition, in some embodiments suture may include a third material, and in some of these embodiments the third material may be a shape-memory material.
In further embodiments, suture may include a sheath layer and a core layer and at least one of these layers may include the first shape-memory material. In certain embodiments, the core layer may include braided core filaments, parallel core filaments, and/or segmented core filaments. In yet other embodiments, the suture may include a sheath layer, an intermediate layer, and a core layer. In certain of these embodiments, the core layer may include braided core filaments, parallel core filaments, and/or segmented core filaments.
In accordance with another aspect, there is provided a self-retaining suture system which includes at least one such suture.
In accordance with another aspect, in some embodiments there is provided a method of manufacturing a shape-memory self-retaining suture. In some embodiments, the method may include providing a filament, coating the filament with a first shape-memory material, and forming retainers on the coated filament. The retainers may be formed by cutting into the filament, removing material from the filament, and/or providing retainer bodies having an inner surface and an outer surface and affixing the retainer bodies to the filament. In particular embodiments, the method may include coating the retainer bodies on at least part of the outer retainer surface. In some embodiments, the retainer bodies may include at least in part shape-memory material.
In accordance with yet another aspect, in some embodiments there is provided a method of manufacturing a shape-memory self-retaining suture, including providing a filament, forming retainers on the filament, and coating the filament with a first shape-memory material. The retainers may be formed by cutting into the filament, removing material from the filament, and/or providing retainer bodies having an inner surface and an outer surface and affixing the retainer bodies to the filament.
In accordance with yet another aspect, in some embodiments there is provided a method of manufacturing a shape-memory self-retaining suture, including providing a filament made up at least in part of a first shape-memory material and forming retainers on the filament. The retainers may be formed by cutting into the filament, removing material from the filament, and/or providing retainer bodies having an inner surface and an outer surface and affixing the retainer bodies to the filament. In some embodiments, the retainer bodies may include at least in part shape-memory material.
In accordance with yet another aspect, in some embodiments there is provided a method of manufacturing a shape-memory self-retaining suture, including providing suture material made up at least in part of shape-memory material, providing a mold for forming self-retaining sutures, and injecting the material through the mold. In other embodiments, there is provided a method of manufacturing a shape-memory self-retaining suture, including providing suture material, providing a mold for forming self-retaining sutures, injecting the suture material through the mold to form a suture, and coating the suture with shape-memory material. In yet other embodiments, there is provided a method of manufacturing a shape-memory self-retaining suture, including providing suture material made up at least in part of shape-memory material, providing a die for forming self-retaining sutures, and stamping said material with the die. In yet additional embodiments, there is provided a method of manufacturing a shape-memory self-retaining suture, including providing suture material, providing a die for forming self-retaining sutures, and stamping the suture material with the die to form a suture, and coating the suture with shape-memory material.
In some embodiments of the methods of manufacturing a shape-memory self-retaining suture, the method may further include incorporating a therapeutic agent into the suture. In certain embodiments, the method may further include coating the self-retaining suture with a therapeutic agent.
In accordance with yet another aspect, there is provided in some embodiments a method of performing a surgical procedure, including providing a shape-memory self-retaining suture having a first form and a second form, wherein a transition in the suture from the first form to the second form is effectuated by a transition stimulus, applying the transition stimulus to the suture to transition the suture into its second form, deploying the suture into tissue, and allowing the suture to revert to its first form. In other embodiments, there is provided a method of performing a surgical procedure, including providing a shape-memory self-retaining suture having a deployment form and a deployed form, wherein a transition in the suture from the deployment form to the deployed form is effectuated by a transition stimulus, deploying the suture into tissue and applying the transition stimulus to the suture to transition the suture into its deployed form. In some embodiments of these methods, the transition stimulus may be one or more of the following: a selected electric field, a selected magnetic field, electromagnetic radiation of a selected magnitude, a selected temperature, a selected pressure, a selected pH, a selected chemical environment, or a selected solvation environment.
In yet other embodiments, there is provided a method of performing a surgical procedure in tissue, including providing a shape-memory self-retaining suture having a deployment form and an in vivo form, wherein a transition in the suture from the deployment form to the in vivo form is effectuated by a physiological condition of the tissue, and deploying the suture into the tissue. In some embodiments, the physiological condition may be is physiological temperature and/or physiological pH.
The details of one or more embodiments are set forth in the description below. Other features, objects and advantages will be apparent from the description, the drawings, and the claims. In addition, the disclosures of all patents, patent applications and publications referenced herein are incorporated by reference in their entirety.
The details of one or more aspects or embodiments are set forth in the description below. Other features, objects and advantages will be apparent from the description, the drawings, and the claims. In addition, the disclosures of all patents and patent applications referenced herein are incorporated by reference in their entirety.
Features of the invention, its nature and various advantages will be apparent from the accompanying drawings and the following detailed description of various embodiments.
Definitions of certain terms that may be used hereinafter include the following.
“Self-retaining system” refers to a self-retaining suture together with devices for deploying the suture into tissue. Such deployment devices include, without limitation, suture needles, cannulas and other deployment devices as well as sufficiently rigid and sharp ends on the suture itself to penetrate tissue.
“Self-retaining suture” refers to a suture that comprises features on the suture filament for engaging tissue without the need for a knot or suture anchor.
“Tissue retainer” (or simply “retainer”) or “barb” refers to a physical feature of a suture filament which is adapted to mechanically engage tissue and resist movement of the suture in at least one axial directions. By way of example only, tissue retainer or retainers can include hooks, projections, barbs, darts, extensions, bulges, anchors, protuberances, spurs, bumps, points, cogs, tissue engagers, traction devices, surface roughness, surface irregularities, surface defects, edges, facets and the like. In certain configurations, tissue retainers are adapted to engage tissue to resist movement of the suture in a direction other than the direction in which the suture is deployed into the tissue by the surgeon, by being oriented to substantially face the deployment direction. In some embodiments the retainers lie flat when pulled in the deployment direction and open or “fan out” when pulled in a direction contrary to the deployment direction. As the tissue-penetrating end of each retainer faces away from the deployment direction when moving through tissue during deployment, the tissue retainers should not catch or grab tissue during this phase. Once the self-retaining suture has been deployed, a force exerted in another direction (often substantially opposite to the deployment direction) causes the retainers to be displaced from the deployment position (i.e. resting substantially along the suture body), forces the retainer ends to open (or “fan out”) from the suture body in a manner that catches and penetrates into the surrounding tissue, and results in tissue being caught between the retainer and the suture body; thereby “anchoring” or affixing the self-retaining suture in place. In certain other embodiments, the tissue retainers may be configured to permit motion of the suture in one direction and resist movement of the suture in another direction without fanning out or deploying. In certain other configurations, the tissue retainer may be configured or combined with other tissue retainers to resist motion of the suture filament in both directions. Typically a suture having such retainers is deployed through a device such as a cannula which prevents contact between the retainers and the tissue until the suture is in the desired location.
“Retainer configurations” refers to configurations of tissue retainers and can include features such as size, shape, flexibility, surface characteristics, and so forth. These are sometimes also referred to as “barb configurations”.
“Bidirectional suture” refers to a self-retaining suture having retainers oriented in one direction at one end and retainers oriented in the other direction at the other end. A bidirectional suture is typically armed with a needle at each end of the suture thread. Many bidirectional sutures have a transition segment located between the two barb orientations.
“Transition segment” refers to a retainer-free (barb-free) portion of a bidirectional suture located between a first set of retainers (barbs) oriented in one direction and a second set of retainers (barbs) oriented in another direction. The transition segment can be at about the midpoint of the self-retaining suture, or closer to one end of the self-retaining suture to form an asymmetrical self-retaining suture system.
“Suture thread” refers to the filamentary body component of the suture. The suture thread may be a monofilament, or comprise multiple filaments as in a braided suture. The suture thread may be made of any suitable biocompatible material, and may be further treated with any suitable biocompatible material, whether to enhance the sutures' strength, resilience, longevity, or other qualities, or to equip the sutures to fulfill additional functions besides joining tissues together, repositioning tissues, or attaching foreign elements to tissues.
“Monofilament suture” refers to a suture comprising a monofilamentary suture thread.
“Braided suture” refers to a suture comprising a multifilamentary suture thread. The filaments in such suture threads are typically braided, twisted, or woven together.
“Degradable suture” (also referred to as “biodegradable suture” or “absorbable suture”) refers to a suture which, after introduction into a tissue is broken down and absorbed by the body. Typically, the degradation process is at least partially mediated by, or performed in, a biological system. “Degradation” refers to a chain scission process by which a polymer chain is cleaved into oligomers and monomers. Chain scission may occur through various mechanisms, including, for example, by chemical reaction (e.g., hydrolysis, oxidation/reduction, enzymatic mechanisms or a combination of these) or by a thermal or photolytic process. Polymer degradation may be characterized, for example, using gel permeation chromatography (GPC), which monitors the polymer molecular mass changes during erosion and breakdown. Degradable suture material may include polymers such as polyglycolic acid, copolymers of glycolide and lactide, copolymers of trimethylene carbonate and glycolide with diethylene glycol (e.g., MAXON™, Tyco Healthcare Group), terpolymer composed of glycolide, trimethylene carbonate, and dioxanone (e.g., BIOSYN™ [glycolide (60%), trimethylene carbonate (26%), and dioxanone (14%)], Tyco Healthcare Group), copolymers of glycolide, caprolactone, trimethylene carbonate, and lactide (e.g., CAPROSYN™, Tyco Healthcare Group). A dissolvable suture can also include partially deacetylated polyvinyl alcohol. Polymers suitable for use in degradable sutures can be linear polymers, branched polymers or multi-axial polymers. Examples of multi-axial polymers used in sutures are described in U.S. Patent Application Publication Nos. 2002/0161168, 2004/0024169, and 2004/0116620. Sutures made from degradable suture material lose tensile strength as the material degrades. Degradable sutures can be in either a braided multifilament form or a monofilament form.
“Non-degradable suture” (also referred to as “non-absorbable suture”) refers to a suture comprising material that is not degraded by chain scission such as chemical reaction processes (e.g., hydrolysis, oxidation/reduction, enzymatic mechanisms or a combination of these) or by a thermal or photolytic process. Non-degradable suture material includes polyamide (also known as nylon, such as nylon 6 and nylon 6,6), polyester (e.g., polyethylene terephthlate), polytetrafluoroethylene (e.g., expanded polytetrafluoroethylene), polyether-ester such as polybutester (block copolymer of butylene terephthalate and polytetra methylene ether glycol), polyurethane, metal alloys, metal (e.g., stainless steel wire), polypropylene, polyethelene, silk, and cotton. Sutures made of non-degradable suture material are suitable for applications in which the suture is meant to remain permanently or is meant to be physically removed from the body.
“Suture diameter” refers to the diameter of the body of the suture. It is to be understood that a variety of suture lengths may be used with the sutures described herein and that while the term “diameter” is often associated with a circular periphery, it is to be understood herein to indicate a cross-sectional dimension associated with a periphery of any shape. Suture sizing is based upon diameter. United States Pharmacopeia (“USP”) designation of suture size runs from 0 to 7 in the larger range and 1-0 to 11-0 in the smaller range; in the smaller range, the higher the value preceding the hyphenated zero, the smaller the suture diameter. The actual diameter of a suture will depend on the suture material, so that, by way of example, a suture of size 5-0 and made of collagen will have a diameter of 0.15 mm, while sutures having the same USP size designation but made of a synthetic absorbable material or a non-absorbable material will each have a diameter of 0.1 mm. The selection of suture size for a particular purpose depends upon factors such as the nature of the tissue to be sutured and the importance of cosmetic concerns; while smaller sutures may be more easily manipulated through tight surgical sites and are associated with less scarring, the tensile strength of a suture manufactured from a given material tends to decrease with decreasing size. It is to be understood that the sutures and methods of manufacturing sutures disclosed herein are suited to a variety of diameters, including without limitation 7, 6, 5, 4, 3, 2, 1, 0, 1-0, 2-0, 3-0, 4-0, 5-0, 6-0, 7-0, 8-0, 9-0, 10-0 and 11-0.
“Suture deployment end” refers to an end of the suture to be deployed into tissue; one or both ends of the suture may be suture deployment ends. The suture deployment end may be attached to a deployment device such as a suture needle, or may be sufficiently sharp and rigid to penetrate tissue on its own.
“Armed suture” refers to a suture having a suture needle on at least one suture deployment end.
“Needle attachment” refers to the attachment of a needle to a suture requiring same for deployment into tissue, and can include methods such as crimping, swaging, using adhesives, and so forth. The suture thread is attached to the suture needle using methods such as crimping, swaging and adhesives. Attachment of sutures and surgical needles is described in U.S. Pat. Nos. 3,981,307, 5,084,063, 5,102,418, 5,123,911, 5,500,991, 5,722,991, 6,012,216, and 6,163,948, and U.S. Patent Application Publication No. US 2004/0088003). The point of attachment of the suture to the needle is known as the swage.
“Suture needle” refers to needles used to deploy sutures into tissue, which come in many different shapes, forms and compositions. There are two main types of needles, traumatic needles and atraumatic needles. Traumatic needles have channels or drilled ends (that is, holes or eyes) and are supplied separate from the suture thread and are threaded on site. Atraumatic needles are eyeless and are attached to the suture at the factory by swaging or other methods whereby the suture material is inserted into a channel at the blunt end of the needle which is then deformed to a final shape to hold the suture and needle together. As such, atraumatic needles do not require extra time on site for threading and the suture end at the needle attachment site is generally smaller than the needle body. In the traumatic needle, the thread comes out of the needle's hole on both sides and often the suture rips the tissues to a certain extent as it passes through. Most modern sutures are swaged atraumatic needles. Atraumatic needles may be permanently swaged to the suture or may be designed to come off the suture with a sharp straight tug. These “pop-offs” are commonly used for interrupted sutures, where each suture is only passed once and then tied. For barbed sutures that are uninterrupted, these atraumatic needles are preferred.
Suture needles may also be classified according to the geometry of the tip or point of the needle. For example, needles may be (i) “tapered” whereby the needle body is round and tapers smoothly to a point; (ii) “cutting” whereby the needle body is triangular and has a sharpened cutting edge on the inside; (iii) “reverse cutting” whereby the cutting edge is on the outside; (iv) “trocar point” or “taper cut” whereby the needle body is round and tapered, but ends in a small triangular cutting point; (v) “blunt” points for sewing friable tissues; (vi) “side cutting” or “spatula points” whereby the needle is flat on top and bottom with a cutting edge along the front to one side (these are typically used for eye surgery).
Suture needles may also be of several shapes including, (i) straight, (ii) half curved or ski, (iii) ¼ circle, (iv) ⅜ circle, (v) ½ circle, (vi) ⅝ circle, (v) and compound curve.
Suturing needles are described, for example, in U.S. Pat. Nos. 6,322,581 and 6,214,030 (Mani, Inc., Japan); and 5,464,422 (W. L. Gore, Newark, Del.); and 5,941,899; 5,425,746; 5,306,288 and 5,156,615 (US Surgical Corp., Norwalk, Conn.); and 5,312,422 (Linvatec Corp., Largo, Fla.); and 7,063,716 (Tyco Healthcare, North Haven, Conn.). Other suturing needles are described, for example, in U.S. Pat. Nos. 6,129,741; 5,897,572; 5,676,675; and 5,693,072. The sutures described herein may be deployed with a variety of needle types (including without limitation curved, straight, long, short, micro, and so forth), needle cutting surfaces (including without limitation, cutting, tapered, and so forth), and needle attachment techniques (including without limitation, drilled end, crimped, and so forth). Moreover, the sutures described herein may themselves include sufficiently rigid and sharp ends so as to dispense with the requirement for deployment needles altogether.
“Needle diameter” refers to the diameter of a suture deployment needle at the widest point of that needle. While the term “diameter” is often associated with a circular periphery, it is to be understood herein to indicate a cross-sectional dimension associated with a periphery of any shape.
“Wound closure” refers to a surgical procedure for closing of a wound. An injury, especially one in which the skin or another external or internal surface is cut, torn, pierced, or otherwise broken is known as a wound. A wound commonly occurs when the integrity of any tissue is compromised (e.g., skin breaks or burns, muscle tears, or bone fractures). A wound may be caused by an act, such as a puncture, fall, or surgical procedure; by an infectious disease; or by an underlying medical condition. Surgical wound closure facilitates the biological event of healing by joining, or closely approximating, the edges of those wounds where the tissue has been torn, cut, or otherwise separated. Surgical wound closure directly apposes or approximates the tissue layers, which serves to minimize the volume new tissue formation required to bridge the gap between the two edges of the wound. Closure can serve both functional and aesthetic purposes. These purposes include elimination of dead space by approximating the subcutaneous tissues, minimization of scar formation by careful epidermal alignment, and avoidance of a depressed scar by precise eversion of skin edges.
‘Tissue elevation procedure” refers to a surgical procedure for repositioning tissue from a lower elevation to a higher elevation (i.e. moving the tissue in a direction opposite to the direction of gravity). The retaining ligaments of the face support facial soft tissue in the normal anatomic position. However, with age, gravitational effects and loss of tissue volume effect downward migration of tissue, and fat descends into the plane between the superficial and deep facial fascia, thus causing facial tissue to sag. Face-lift procedures are designed to lift these sagging tissues, and are one example of a more general class of medical procedure known as a tissue elevation procedure. More generally, a tissue elevation procedure reverses the appearance change that results from effects of aging and gravity over time, and other temporal effects that cause tissue to sag, such as genetic effects. It should be noted that tissue can also be repositioned without elevation; in some procedures, tissues are repositioned laterally (away from the midline), medially (towards the midline) or inferiorly (lowered) in order to restore symmetry (i.e. repositioned such that the left and right sides of the body “match”).
“Medical device” or “implant” refers to any object placed in the body for the purpose of restoring physiological function, reducing/alleviating symptoms associated with disease, and/or repairing and/or replacing damaged or diseased organs and tissues. While normally composed of biologically compatible synthetic materials (e.g., medical-grade stainless steel, titanium and other metals or polymers such as polyurethane, silicon, PLA, PLGA and other materials) that are exogenous, some medical devices and implants include materials derived from animals (e.g., “xenografts” such as whole animal organs; animal tissues such as heart valves; naturally occurring or chemically-modified molecules such as collagen, hyaluronic acid, proteins, carbohydrates and others), human donors (e.g., “allografts” such as whole organs; tissues such as bone grafts, skin grafts and others), or from the patients themselves (e.g., “autografts” such as saphenous vein grafts, skin grafts, tendon/ligament/muscle transplants). Medical devices that can be used in procedures in conjunction with the present invention include, but are not restricted to, orthopedic implants (artificial joints, ligaments and tendons; screws, plates, and other implantable hardware), dental implants, intravascular implants (arterial and venous vascular bypass grafts, hemodialysis access grafts; both autologous and synthetic), skin grafts (autologous, synthetic), tubes, drains, implantable tissue bulking agents, pumps, shunts, sealants, surgical meshes (e.g., hernia repair meshes, tissue scaffolds), fistula treatments, spinal implants (e.g., artificial intervertebral discs, spinal fusion devices, etc.) and the like.
As discussed above, the present invention provides compositions, configurations, methods of manufacturing and methods of using shape-memory self-retaining sutures in surgical procedures which greatly increase the ability of the self-retaining sutures to anchor into the surrounding tissue to provide superior holding strength and improve clinical performance.
Shape-memory materials are materials which have the ability to memorize one or more shapes different than the current temporary shape and transition between the shapes in response to a stimulus. A wide variety of materials are known to exhibit shape-memory effects including, for example, polymers, thermoplastics, metal alloys, hydrogels and ceramics. A shape-memory material transitions from one shape to another shape in response to a transition stimulus—typically a temperature change. However, a wide variety of different transition stimuli can be used to effect transition between shapes in shape-memory materials including, for example, temperature, electromagnetic radiation, electrical current, magnetic fields, pH, and solvation (including, but not limited to water solvation). The transition stimulus is typically dependent upon the shape-memory material.
Shape-memory metal alloys are known that transition between shapes in response to a temperature stimulus. Nickel-Titanium alloy known as NITINOL is a superelastic shape-memory alloy that is often used in medical applications. Nitinol is typically composed of approximately 55% Nickel by weight but making small changes in the composition can change the transition temperature of the alloy significantly. The temperature stimulus causes a transition in crystalline structure. When NITINOL is deformed below its transition temperature it will remain in the deformed shape until heated above its transition temperature, at which time it will return to its original shape. The shape-memory property of NITINOL is due to a temperature-dependent phase transformation from a low-symmetry to a high symmetry crystallographic structure. Those crystal structures are known as martensite (at lower temperatures) and austenite (at higher temperatures).
Shape-memory alloys may have different kinds of shape-memory effect including one-way and two-way shape-memory. In the one-way shape-memory effect a piece of the alloy transitions from a first shape at the low temperature to a permanent shape at a temperature above the transition temperature but does not substantially change shape upon returning below the transition temperature. In the two way shape-memory effect the alloy may regain some of the first shape upon returning below the transition temperature. Shape-memory metals include for example the alloys of: Ni—Ti, Ag—Cd, Au—Cd, Cu—Al—Ni, Cu—Sn, Cu—Zn, Cu—Zn—Si, Fe—Pt, Mn—Cu, and Fe—Mn—Si in suitable ratios.
Shape-memory polymers also transition between shapes in response to an external stimulus. Polymers with shape-memory have a current shape and one or more stored shapes. Dual-shape and triple-shape polymers have been described. A first stored shape is produced by conventional methods and the configuration of that shape is largely determined by covalent bonds between the polymer chains. The material is then deformed into a second (and possibly third) temporary form under conditions in which the second (and possibly third) form is fixed by mechanical connections made by particular “switching segment”. The transformation into the second (and possibly third) temporary forms is a process called programming. The polymer maintains the second (and possibly third) form until another of the shapes is recalled by a predetermined external stimulus. Shape-memory polymers including dual-shape and triple-shape polymers are disclosed for example in U.S. Pat. Nos. 6,160,084, 6,388,043, 6,720,402, 6,852,825, 7,037,984 and U.S. Patent Publications 2004/0014929, 2006/0116503, 2006/0140999, 2006/0257629, 2007/0088135 to Lendlein et al. which are incorporated herein by reference.
The shape-memory effect in shape-memory-polymers is due to a heterogeneous molecular network structure, which contains meltable “switching segments” among other harder segments. Applying a stimulus causes the crystallized switching segments to “melt” and the material recovers a form controlled (“memorized”) by other elements of the crystalline structure of the polymer. A shape-memory polymer may have multiple different “switching segments” which melt in response to different stimuli thus permitting a plurality of shapes to be memorized. The transition stimulus for shape memory polymers is often temperature, but can also be an electric field, magnetic field, electromagnetic radiation (e.g. light), pH change, chemical change or solvation change (e.g. water). In some instances the transition stimulus is a means for raising the temperature of the polymer. Passing an electric current through a conductive polymer can be used to raise the temperature by resistive heating. Applying a fluctuating magnetic field to a polymer can be used to heat a polymer having ferromagnetic properties. Illuminating a polymer with electromagnetic radiation can be used to heat a polymer which absorbs (or is treated to absorb) the particular wavelength used. However, other transition stimuli such as pH, chemical change and solvation may be used to “melt” the switching segment without a change in temperature.
A shape memory material including a polymer or alloy may be incorporated in a self-retaining suture to provide shape memory attributes to the filament and/or retainers of the self-retaining suture. The particular shape-memory material selected depends upon the shape change desired and also choosing a transition stimulus compatible with the application. For example, where a shape-memory material is desired to undergo a shape-change after implantation in tissue, it is desirable that the transition stimulus be applied without damaging the tissue in which the material is implanted. In some embodiments, the material is selected such that the transition stimulus is a physiological property of the tissue in which the material will be implanted—such that the material undergoes a shape change automatically upon implantation in the tissue. In other embodiments the material is selected such that the transition stimulus is not a physiological property of the tissue in which the material will be implanted—such that the transition stimulus must be supplied to the material from an external device before the material undergoes a shape change.
The present invention provides compositions, configurations, methods of manufacturing shape-memory self-retaining sutures and methods of using shape-memory self-retaining sutures in surgical procedures Shape-memory self-retaining sutures incorporate a shape-memory material in a way which affects the geometry of features of the shape-memory filament before, during or after deployment of the suture into tissue.
In a shape-memory self-retaining suture system, the retainers 130 and/or filament 120 includes a shape-memory component. In some embodiments, the shape-memory component may be used to cause retainers 130 to elevate or lie flat against filament 120 in response to a stimulus. With the retainer 130 elevated, when self-retaining suture thread 102 is moved in the direction of arrow 138, tip 132 or retainer 130 engages tissue surrounding filament 120 and causes retainers 130 to fan out further from filament 120 and engage the tissue with tissue retainer surface 134 thereby preventing movement of the suture in that direction. However, prior to elevation of retainer 130 it may be possible to move shape-memory suture thread 102 in both of directions 136, 138 without interference by retainers 130. Thus, the use of shape-memory suture thread 102 allows for selectable control of the self-retaining features of the shape-memory self-retaining suture system 100.
Shape-memory suture threads as described herein may be produced by any suitable method, including without limitation, one or a combination of injection molding, stamping, cutting, laser, extrusion, and so forth. With respect to cutting, polymeric thread or filaments may be manufactured or purchased for the suture body, and the retainers can be subsequently cut onto the suture body. Such retainers may be hand-cut, laser-cut, or mechanically machine-cut using blades, cutting wheels, grinding wheels, and so forth. During cutting either the cutting device or the suture thread may be moved relative to the other, or both may be moved, to control the size, shape and depth of cut. Particular methods for cutting barbs on a filament are described in U.S. patent application Ser. No. 09/943,733 titled “Method Of Forming Barbs On A Suture And Apparatus For Performing Same” to Genova et al., and U.S. patent application Ser. No. 10/065,280 titled “Barbed Sutures” to Leung et al. both of which are incorporated herein by reference.
In step 262 of
In an alternative embodiment, a retainer 230 may be formed in filament 220 by making a cut into the surface of filament 220. When a retainer 230 is made in this manner, the retainer needs to be elevated above the surface of filament in order to engage tissue. The retainer may be annealed while held in the elevated position at a temperature sufficient to alter the permanent configuration of the filament. The retainers may be elevated using a range of different technologies, including mechanically lifting each retainer and wrapping the filament around a mandrel. Technology for elevating retainers is disclosed in U.S. Provisional Patent Application 61/030,423 entitled “Method And Apparatus For Elevating Retainers On Self-Retaining Sutures” to Goraitchouk et al. which is incorporated herein by reference.
In steps 264, 266 and 268, of
In step 268 of
Retainer 230 will remain flush against filament 220 in the temporary configuration shown in
Where the transition stimulus is a temperature, the shape-memory polymer is heated above the transition temperature in step 270. The shape-memory polymer may be selected such that the transition temperature is a physiological tissue temperature. However as shown in
Applications of Self-Retaining Sutures with Shape-Memory Properties
As shown in
As shown in
In another alternative embodiment, also illustrated in
As shown, in
The shape-memory properties of a shape-memory suture thread can also be utilized to affect the size and/or shape of the filament instead of the retainers of the self-retaining suture. Shape-memory can be used to store a temporary filament shape instead of or in addition to using shape-memory to affect retainer elevation. Thus, in a simple example, the shape-memory effect may be used to reduce the length of a suture after deployment in order to approximate a wound.
As shown in
In alternative embodiments, an external stimulus may be required to cause elevation of the retainers. Such an external stimulus may be, for example, the application of heat to cause a temperature rise in the suture in excess of natural body temperature. The temperature rise can be caused by heating the suture outside the body prior to deployment. Alternatively, magnetic particles may be embedded in the material of the suture and caused to heat the suture material by magnetic induction caused by application of a magnetic filed through the tissue of the subject after deployment of the suture. Additionally, shape-memory polymers which contract upon application of UV light, pH or other stimuli which may be applied to the suture after deployment in the tissues may be used. In such cases, the transition stimulus may be controlled in order to cause all or part of filament 420 to contract thus a measure of control of the wound approximation and/or the force applied to tissues 490, 491 may be achieved.
As shown in
Self-retaining suture systems may comprise more than two arms. A self-retaining suture system may have one, two or more arms including up to about ten arms or more depending upon the application. For example, as shown in
Self-retaining suture systems having more than two arms, such as shown in
Self-retaining suture systems comprising more than two arms may be made using the shape-memory materials described herein and/or non-shape-memory materials. For example the self-retaining suture system 460 of
Shape-memory can be used to store a temporary filament shape instead of or in addition to using shape-memory to affect retainer elevation. Thus, in another simple example, the shape-memory effect may be used to elevate tissue after deployment.
A shape-memory self-retaining suture may be used for tissue elevation procedures in all parts of the body where tissue elevation procedures are performed. For example shape-memory self-retaining suture may be used in procedures, including, but not limited to face-lifts, brow-lifts, breast-lifts, neck-lifts, thigh lifts, and buttock lifts. As described with respect to
The use of shape-memory self-retaining sutures in tissue elevation applications has many advantages. The elevation may be carried out some-time subsequent to the deployment step. For example, the suture may be deployed and then the patient released for a recovery period. Some time later, the patient returns to the physicians' office. The physician can apply the transition stimulus to the suture to elevate the tissue while the patient is watching in a mirror. Thus the patient can guide the physician to achieve the aesthetic effect desired by the patient. Moreover, if the transition stimulus is not applied to all regions of the shape-memory self-retaining suture, if further elevation is required at a later date, the patient may return and have the transition stimulus applied to further regions of the shape-memory self-retaining suture to cause more elevation. The time period between the deployment and elevation steps also allows the shape-memory self-retaining suture to become better anchored in the tissue prior to elevation allowing for a better result. Furthermore, swelling caused by suture deployment can dissipate prior to elevation such that the true effects of the elevation can be directly observed without masking by the effects of inflammation and swelling.
Triple-shape shape-memory polymers allow an article to be made which has two temporary shapes in addition to its permanent shape. Examples of such materials are described in Bellin et al., “Polymeric triple-shape materials” PNAS 103:48 pp. 18043-47 (2006) which is incorporated herein by reference. Triple-shape-memory polymers have two types of meltable switching segment. Each switching segment responds to a different transition stimulus. The article is formed from the melted polymer as previously described. The polymer is then raised to a temperature above the transition temperature for both of the switching segments. The article is then deformed to a first temporary shape and held in the first temporary shape while the temperature is reduced below the transition temperature of the first switching segment. The article is then deformed to a second temporary shape while the temperature is between the transition temperature of the first switching segments and the transition temperature of the second switching segments. The article is held in the second temporary shape while the temperature is reduced below the transition temperature of the second switching segment. After the article is cooled below the transition temperature of the second switching segment, the deforming force may be removed and the article will retain the second temporary shape. Subsequently a first external transition stimulus can raise the temperature of the article to a temperature above the transition temperature of the second switching segment. At this temperature, the second switching segment melts and the second temporary shape is lost and the first temporary shape is recovered. The article will retain this second temporary shape until a second external transition stimulus raise the temperature of the article to a temperature above the transition temperature of the first switching segment. At this temperature, the first switching segment melts and the first temporary shape is lost and the permanent shape is recovered.
Examples of the use of triple-shape shape-memory polymers in self-retaining sutures are illustrated in
Self-retaining suture 500 is be deployed into tissues in the configuration shown in
Many different programmed configurations of self-retaining suture made of triple-shape shape-memory polymers are possible.
In alternative embodiments of the present invention retainers are formed in the surface of a composite shape-memory filament. In a composite shape memory filament, the filament includes two or more materials. At least one of the two or more materials is a shape memory material. It is advantageous to use composite shape-memory filaments to make self-retaining sutures. For example, by forming retainers in a composite shape-memory filament, a shape-memory self-retaining suture can be created in which the retainers elevate without requiring external mechanical elevation or in which the retainers self-elevate to augment the effects of mechanical elevation to produce a greater combined elevation. This is advantageous as it reduces the need for mechanical elevation which is time consuming, expensive and has the potential for weakening the retainers. Depending upon the combination of materials from which the composite shape-memory filament is made and the transition temperature of the shape memory component (or components), the retainers can be made to elevate prior to deployment, upon deployment into tissue, or after deployment into tissue.
A composite filament can be made in many different ways. In accordance with one embodiment of the invention, a composite monofilament 720 is formed by co-extruding two materials. As shown in
In main extruder 730, the two melted materials 711, 716 flow through two flow paths 736, 738 through an extrusion die 732 which controls the arrangement of the two materials 711, 716 when the materials combine in composite flow channel 739. The two materials are introduced into in composite flow channel 739 as shown and then extruded from die 732 through die exit 734. Die 732 and flow channels 736, 738, 739 are designed and operated such that the two materials 711 and 716 do not mix in composite flow channel 739. When making a composite shape-memory filament, at least one of the materials provided to the extrusion die is a shape-memory polymer.
The fiber 740 which is still melted material is then solidified by air or liquid cooling in quenching station 750. Quenching station 750 optionally includes a quenching bath 752 for liquid cooling. The solidified filament 742 is then drawn in drawing machine 760. Typically the solidified filament is drawn at temperatures between 70-80% of melting point (Celsius). Usually the suture is extruded then drawn on several rollers 762 with decreasing temperature. Drawing of the filament reduces the diameter of the filament while at the same time orienting the molecules of the polymers of the filament and enhancing the tensile strength of the filament. Typically drawing is conducted in a continuous process by winding the filament around a series of rollers 762 where each roller in the series has a slightly higher roller surface speed. The speed differential of the rollers results in stretching of the filament as the filament passes from roller to roller. The filament may also be tempered by one or more heating and cooling steps before, during or after the drawing process. As illustrated in
The core filament may consist entirely of a non-shape-memory material, or may consist entirely of shape-memory material or may be a mixture of shape-memory materials and non-shape-memory materials. In one example, the core filament may comprise a braid of heterogeneous yarns wherein the heterogeneous yarns contain filaments made from a shape-memory alloy and non-biodegradable polymers. Exemplary yarns are disclosed in U.S. patent application Ser. No. 10/972,464 titled “Yarns Containing Filaments Made From Shape-memory Alloys” which is incorporated herein by reference.
Although extrusion has been illustrated in
Depending upon the configuration of the extruders, die, spin block, spinneret, or other manufacturing equipment, a composite filament suitable for creating a self-retaining suture in accordance with embodiments of the present invention can be created with a wide variety of different arrangements of different materials. Furthermore, composite filaments can be made using 2, 3, 4 or even more different component materials if necessary or desired for the particular application. Examples of possible configurations of composite filaments are useful in specific embodiments of the present invention and are described below with respect to
As shown in
The configuration of the particular materials in the composite filament will depend upon the characteristics of the materials and the amount of material necessary to fulfill the role of the filament. For example, in one embodiment sheath 814, may be made from a shape-memory polymer such that the elevation of retainers formed from the material of the sheath may be programmed. The depth of the sheath may be chosen such that the retainers when formed are formed entirely out of the sheath material. Alternatively, core 812 may be made from a shape memory material thus allowing the length of shape of the suture filament to be programmed. In some embodiments, different shape memory materials (having different transition stimuli) may be selected for core 812 and sheath 814 allowing retainer elevation and filament length and shape to be programmed and actuated somewhat independently.
Referring now to
As shown in
This transition stimulus can be selected such that the sheath material shrinks when exposed to body temperature, moisture, pH or another natural chemical property of tissue to which the sheath material will only be exposed when deployed in the body. For example, polyether-ester shape-memory polymers can be activated to undergo contraction at transition temperatures near body temperature. Core material 950 is selected that does not shrink or shrinks less than the sheath material and is also selected to enhance the mechanical strength of the suture. Thus, when the suture is deployed into tissues of the body, sheath 952 contracts in the direction of arrows 910, and core 950 does not contract. Contraction of the sheath causes the retainers 930 to elevate from the position shown in
In alternative embodiments, an external stimulus may be required to cause elevation of the retainers. Such an external stimulus may be, for example, the application of heat to cause a temperature rise in the suture in excess of natural body temperature. The temperature rise can be caused by heating the suture outside the body prior to deployment. Alternatively, magnetic particles may be embedded in the material of the suture and caused to heat the suture material by magnetic induction caused by application of a magnetic field through the tissue of the subject after deployment of the suture. Additionally, shape-memory polymers which contract upon application of UV light, pH or other stimuli which may be applied to the suture after deployment in the tissues may be used in sheath 952. The external stimulus should be a stimulus that can reach and affect the suture without causing injury to tissue.
In alternative embodiments, retainers may be formed separately from a filament and then attached to a filament. Methods of manufacturing sutures with frusto-conical retainers have also been described, for example, in European Patent 1 075 843 and U.S. Pat. Publication No. 2007/0038429. Particular configurations of retainers are disclosed in United States Provisional Patent Application ANGIO-1016US0 entitled “Self-Retaining Sutures With Bi-Directional Retainers Or Uni-Directional Retainers” to Goraltchouk et al. In accordance with embodiments of the present invention, either the filament or the retainers or both may comprise a shape-memory material such as a shape-memory polymer or shape-memory alloy. The shape memory components may be programmed/trained prior to assembly of the retainers and filament thereby allowing the use of shape-memory components having training/programming requirements which are incompatible with the other components of the self-retaining suture. For example, programming of a NITINOL alloy requires a temperature of several hundred degrees centigrade for several minutes. Many polymer filaments will melt or burn under these conditions. Thus, if NITINOL shape-memory components are to be combined with polymer components to make a shape-memory self-retaining suture it is preferable to train/program the NITINOL components prior to integration with the polymer components.
As shown in
As shown in
As described above with respect to
Referring to
As shown in
The connector may serve not only to connect the filaments of the self-retaining sutures but also to apply tension and reposition the self-retaining sutures. As shown in
Reducing the diameter of ring 1046 draws each of the self-retaining suture threads 1042 in towards the center as shown by arrows 1049. The diameter of ring 1046 may be fixed prior to deploying self-retaining multi-arm self-retaining suture system 1040. However, in some applications it is desirable to deploy the threads of multi-arm self-retaining suture system 1040 into tissue with ring 1046 at a large diameter and then cause ring 1046 to contract drawing the tissues in which the threads 1042 are deployed towards each other in the direction of arrows 1049. The reduction in size of ring 1046 may be performed immediately after deployment of threads 1042 or at a later time, or in sequential steps as, for example, where the tissue stretches or swelling reduces over time allowing further approximation of the tissues toward the center point as shown.
It is another advantage of the present invention that the sheath and/or outer layers of the filament may desirably incorporate materials that further promote tissue engagement. In addition to tissue engagement at the retainers, use of tissue engagement-promoting materials in at least part of the suture sheath surface (whether or not such materials also make up all or part of the retainers) can enhance the ability of the sutures to stay in place. One such class of tissue engagement-promoting materials are porous polymers that can be extruded, including both microporous polymers and polymers that can be extruded with bubbles (whether bioabsorbable or nonbioabsorbable). A suture synthesized with such materials in the sheath can have a three-dimensional lattice structure that increases tissue engagement surface area and permits tissue infiltration into the suture body itself, thus having a sheath structure that promotes successful suture use. Moreover, by optimizing pore size, fibroblast ingrowth can be encouraged, further facilitating the suture to be anchored in the tissue. One such microporous polymer is ePTFE (expanded polytetrafluoroethylene). Self-retaining incorporating ePTFE (and related microporous materials) in the sheath are well-suited to uses requiring a strong and permanent lift (such as breast lifts, face lifts, and other tissue repositioning procedures), as tissue infiltration of the suture results in improved fixation and engraftment of the suture and the surrounding tissue thus providing superior hold and greater longevity of the lift. Furthermore, an agent can be utilized in conjunction with the suture (introduced separately or adhered to the suture or incorporated into a material of the suture) to encourage fibrosis. Fibrosis-inducing agents which may be used in conjunction with a self-retaining suture in accordance with the present invention are described in U.S. Pat. No. 7,166,570 titled “Medical Implants And Fibrosis-Inducing Agents” to Hunter et al. which is incorporated herein by reference.
Additionally, self-retaining sutures described herein may be provided with therapeutic compositions including, for example, compositions to promote healing and prevent undesirable effects such as scar formation, infection, pain, and so forth. This can be accomplished in a variety of manners, including for example: (a) by directly affixing to the suture a formulation (e.g., by either spraying the suture with a polymer/drug film, or by dipping the suture into a polymer/drug solution), (b) by coating the suture with a substance such as a hydrogel which will in turn absorb the composition, (c) by interweaving formulation-coated thread (or the polymer itself formed into a thread) into the suture structure in the case of multi-filamentary sutures, (d) constructing the suture itself with a composition. Such compositions may include without limitation anti-proliferative agents, anti-thrombotic agents, anti-angiogenic agents, anti-infective agents, fibrosis-inducing agents, anti-scarring agents, lubricious agents, echogenic agents, anti-inflammatory agents, cell cycle inhibitors, analgesics, and anti-microtubule agents. For example, a composition can be applied to the suture before the retainers are formed, so that when the retainers engage, the engaging surface is substantially free of the coating. In this way, tissue being sutured contacts a coated surface of the suture as the suture is introduced, but when the retainer engages, a non-coated surface of the retainer contacts the tissue. Alternatively, the suture may be coated after or during formation of retainers on the suture if, for example, a fully-coated rather than selectively-coated suture is desired. In yet another alternative, a suture may be selectively coated either during or after formation of retainers by exposing only selected portions of the suture to the coating. The particular purpose to which the suture is to be put or the composition may determine whether a fully-coated or selectively-coated suture is appropriate; for example, with lubricious coatings, it may be desirable to selectively coat the suture, leaving, for instance, the tissue-engaging surfaces of the sutures uncoated in order to prevent the tissue engagement function of those surfaces from being impaired. On the other hand, coatings such as those comprising such compounds as anti-infective agents may suitably be applied to the entire suture, while coatings such as those comprising fibrosing agents may suitably be applied to all or part of the suture (such as the tissue-engaging surfaces). The purpose of the suture may also determine the sort of coating that is applied to the suture; for example, self-retaining sutures having anti-proliferative coatings may be used in closing tumor excision sites, while self-retaining sutures with fibrosing coatings may be used in tissue repositioning procedures and those having anti-scarring coatings may be used for wound closure on the skin. As well, the structure of the suture may influence the choice and extent of coating; for example, sutures having an expanded segment may include a fibrosis-inducing composition on the expanded segment to further secure the segment in position in the tissue. Coatings may also include a plurality of compositions either together or on different portions of the suture, where the multiple compositions can be selected either for different purposes (such as combinations of analgesics, anti-infective and anti-scarring agents) or for the synergistic effects of the combination.
In accordance with embodiments of the present invention, the shape memory properties of the suture may be utilized to influence where, when and/or how the therapeutic compounds or materials are exposed to tissue and/or released into the tissue. First, in certain embodiments, self-retaining sutures may be made in which the therapeutic compound or agent is only exposed upon elevation of the retainer. As discussed above, shape-memory materials can be used to make retainers that may be elevated or made to lay flat against the filament in response to a transition stimulus. Thus, for example, where the therapeutic agent is only exposed to tissue on the tissue retainer surface, the therapeutic agent may be protected during insertion of the self-retaining suture into tissue and then the retainer may be elevated by application of a transition stimulus, thereby exposing the therapeutic agent to the tissue.
As shown in
In addition to the general wound closure and soft tissue repair applications, self-retaining sutures can be used in a variety of other indications.
Self-retaining sutures described herein may be used in various dental procedures, i.e., oral and maxillofacial surgical procedures and thus may be referred to as “self-retaining dental sutures.” The above-mentioned procedures include, but are not limited to, oral surgery (e.g., removal of impacted or broken teeth), surgery to provide bone augmentation, surgery to repair dentofacial deformities, repair following trauma (e.g., facial bone fractures and injuries), surgical treatment of odontogenic and non-odontogenic tumors, reconstructive surgeries, repair of cleft lip or cleft palate, congenital craniofacial deformities, and esthetic facial surgery. Self-retaining dental sutures may be degradable or non-degradable, and may typically range in size from USP 2-0 to USP 6-0.
Self-retaining sutures described herein may also be used in tissue repositioning surgical procedures and thus may be referred to as “self-retaining tissue-repositioning sutures”. Such surgical procedures include, without limitation, face lifts, neck lifts, brow lifts, thigh lifts, and breast lifts. Self-retaining sutures used in tissue repositioning procedures may vary depending on the tissue being repositioned; for example, sutures with larger and further spaced-apart retainers may be suitably employed with relatively soft tissues such as fatty tissues. In particular, shape-memory self-retaining sutures may be employed where the shape-memory suture is programmed to shrink in response to the application of a transition stimulus thereby repositioning the tissue in which it is implanted. Thus a self-retaining suture may be anchored in tissue to a stable anatomical feature. Applying a transition stimulus selectively to the self-retaining suture would then lift the tissue towards the stable anatomical feature. The amount of lift could be selected by selective application of the transition stimulus to different regions of the suture.
Self-retaining sutures described herein may also be used in microsurgical procedures that are performed under a surgical microscope (and thus may be referred to as “self-retaining microsutures”). Such surgical procedures include, but are not limited to, reattachment and repair of peripheral nerves, spinal microsurgery, microsurgery of the hand, various plastic microsurgical procedures (e.g., facial reconstruction), microsurgery of the male or female reproductive systems, and various types of reconstructive microsurgery. Microsurgical reconstruction is used for complex reconstructive surgery problems when other options such as primary closure, healing by secondary intention, skin grafting, local flap transfer, and distant flap transfer are not adequate. Self-retaining microsutures have a very small caliber, often as small as USP 9-0 or USP 10-0, and may have an attached needle of corresponding size. The microsutures may be degradable or non-degradable.
Self-retaining sutures as described herein may be used in similarly small caliber ranges for ophthalmic surgical procedures and thus may be referred to as “ophthalmic self-retaining sutures”. Such procedures include but are not limited to keratoplasty, cataract, and vitreous retinal microsurgical procedures. Ophthalmic self-retaining sutures may be degradable or non-degradable, and have an attached needle of correspondingly-small caliber.
Self-retaining sutures can be used in a variety of veterinary applications for a wide number of surgical and traumatic purposes in animal health.
Although the present invention has been shown and described in detail with regard to only a few exemplary embodiments of the invention, it should be understood by those skilled in the art that it is not intended to limit the invention to the specific embodiments disclosed. Various modifications, omissions, and additions may be made to the disclosed embodiments without materially departing from the novel teachings and advantages of the invention, particularly in light of the foregoing teachings. Accordingly, it is intended to cover all such modifications, omissions, additions, and equivalents as may be included within the spirit and scope of the invention as defined by the following claims.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US09/41685 | 4/24/2009 | WO | 00 | 2/8/2011 |
| Number | Date | Country | |
|---|---|---|---|
| 61047682 | Apr 2008 | US |
