Mechanical method and apparatus for bilateral tissue fastening

A mechanical system for bilaterally securing skin tissue preferably utilizes a tissue manipulator apparatus to approximate a portion of an interior surface of each of two pieces of living dermis tissue along a vertical interface below an exterior surface without overlapping either interior surface across the vertical interface. An applicator apparatus includes a driving head portion positioned in the vertical interface and at least partially below the exterior surface and a handle portion positioned at least partially above the exterior surface. The applicator apparatus bilaterally drives at least one portion of the fastener through each piece of the living dermis tissue behind the interior surface of that piece of tissue such that the fastener is positioned below the exterior surface and a portion of the fastener is positioned generally transverse to the vertical interface.

FIELD OF THE INVENTION

The present invention relates generally to the field of surgical instruments such as surgical staplers, clip applicators and sutureless closure devices. More particularly, the present invention relates to a mechanical method and apparatus for fastening tissue, such as skin tissue, with a fastener positioned below the tissue surface that bilaterally secures opposed pieces of tissue.

BACKGROUND OF THE INVENTION

When an opening in tissue is created either through an intentional incision or an accidental wound or laceration, biological healing of the opening commences through the proximity of the opposed living tissue surfaces. If the opening is very large or if its location subjects the wound to continual movement, a physician will seek to forcibly hold the sides of the opening in close proximity so as to promote the healing process.

In the case of skin tissue, for example, healing occurs best when the opposing dermal layers of the skin tissue are held in proximity with each other. Human skin tissue is comprised of three distinct layers of tissue. The epidermal layer, also known as the epidermis, is the outermost layer and includes non-living tissue cells. The dermal layer, or dermis, is the middle layer directly below the epidermal layer and comprises the living tissue of the skin that is the strongest of the three layers. The subcutaneous, or hypodermis layer is the bottom layer of skin tissue and includes less connective tissue making this the weakest layer of skin tissue.

The most prevalent method for forcibly closing a tissue opening is through the use of a suture or “stitches.” As early as the second century, the Greeks were using sutures to physically close skin openings. In its simplest form, a suture is simply a length of material that is attached to a tissue-piercing device, such as a needle, and looped through the opposing sides of an opening. The suture is then pulled tight and the loop closes causing the opposing sides of the tissue to come into close physical proximity. The suture loop is held tight by the tying of a knot or some other locking mechanism. The first sutures were made of animal gut. Eventually other natural suture materials including leather, horsehair, flax, cotton and silk came into use.

As the sciences of medical and materials technology have advanced over the course of the past century, new bioabsorbable materials have been developed to further improve upon the basic suturing concept. Examples of modern improvements to the suturing process include enhancements to the suturing apparatus as shown, for example, in U.S. Pat. Nos. 2,439,383, 2,959,172 and 3,344,790, as well as advances in sutures and suture materials as shown, for example, in U.S. Pat. Nos. 3,123,077, 3,297,033, 3,636,956, 3,792,010 4,027,676 and 4,047,533.

While traditional suturing remains a popular method of effectuating closure of skin openings, the use of staples and staplers as a skin closure technique has become increasingly popular, especially in surgical settings where the opening is created through a purposeful incision. In these settings, the incision tends to make a clean, straight cut with the opposing sides of the incision having consistent and non-jagged surfaces. Typically, stapling of a skin opening, for example, is accomplished by manually approximating the opposing sides of the skin opening and then positioning the stapler so that a staple will span the opening. The stapler is then manipulated such that the staple is driven into the skin with one leg being driven into each side of the skin and the cross-member of the staple extending across the opening external to the skin surface. Generally, the legs of the staple are driven into an anvil causing the staple to deform so as to retain the skin tissue in a compressed manner within the staple. This process can be repeated along the length of the opening such that the entire incision is held closed during the healing process.

While modern suturing and stapling techniques continue to provide an effective manner of effectuating skin closure, there remains a series of inherent disadvantages in using either of these techniques. The standard technique for both suturing and stapling includes puncturing both the epidermis and dermis. This can result in a wound closure having an unaesthetically pleasing appearance on the surface of the skin. The presence of the fastener exposed through the skin surface provides an opportunity for infection and for accidentally catching the fastener and tearing the wound open. In the case of non-absorbable fasteners, further action by a medical professional is necessary in order to remove the fastener once biological healing is complete.

In order to overcome these limitations, practitioners have developed a number of specialized suturing techniques where the suture is passed only through the dermis effectively positioning the suture below the skin surface, or in a subcuticular fashion. A surgeon has the choice of placing individual or interrupted sutures along the length of an opening. Another suturing option is for the surgeon to use a single strand of suture material to place a plurality of continuing suture loops or running sutures along the length of an opening. While the presence of the suture below the surface can improve the aesthetic nature of the closure, it requires greater skill and technique to accomplish effectively and takes longer than conventional external suturing.

While there has been active development of dermal layer suturing techniques, little has been done in the area of staples and staplers for use in connection with the dermal layer. In a series of patents issued to Green et al., including U.S. Pat. Nos. 5,292,326, 5,389,102, 5,489,287 and 5,573,541, a subcuticular stapling method and apparatus are disclosed that were ultimately commercialized as the U.S. Surgical SQS Subcuticular Stapling Apparatus. The Green et al. patents describe a stapling technique employing a handheld apparatus with jaws to proximate, interdigitate and overlap opposing sides of dermal layer tissue along the length of a skin opening. The apparatus then drives a single spike through the interdigitated and overlapped dermal layers of the opposing skin surfaces in order to secure both sides of the dermal tissue on the single spike. Although this technique reduced the time required to effectuate a subcuticular skin closure, the SQS device was not commercially successful in part because the resulting closure produced an undesirable wave-like scar that sometimes did not heal effectively.

While many improvements have been made to mechanical tissue closure techniques, it would be desirable to provide a mechanical tissue closure system that is capable of effectively delivering fasteners below the skin surface so as to produce an efficient and efficacious tissue closure.

SUMMARY OF THE INVENTION

The present invention is a mechanical system for bilaterally securing skin tissue. Preferably, a tissue manipulator is used to approximate a portion of an interior surface of each of two pieces of living dermis tissue along a vertical interface below an exterior surface without overlapping either interior surface across the vertical interface. An applicator apparatus includes a driving head portion positioned in the vertical interface and at least partially below the exterior surface, and a handle portion positioned at least partially above the exterior surface. The applicator apparatus bilaterally drives at least one portion of the fastener through each piece of the living dermis tissue behind the interior surface of that piece of tissue such that the fastener is positioned below the exterior surface and a portion of the fastener is positioned generally transverse to the vertical interface.

Unlike existing mechanical tissue fastening systems, the present invention recognizes the need for and advantages of a fastener system that captures and retains dermal tissue in a compressed state within a preferably bioabsorbable fastener that is not inserted through the epidermal skin layer. The mechanical fastening system of the present invention is able to consistently and repeatedly interface a fastener with a target tissue zone in the dermal layer such that the fastener inserted into the target tissue zone produces an effective and aesthetically pleasing closure of a tissue opening.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

InFIGS. 1-3there is shown a depiction of a typical opening50in the surface of skin52, such as may be made, for example, by a surgical incision or a wound. As illustrated inFIG. 1, for purposes of describing the present invention, opening50may be described as having a length or longitudinal orientation parallel to the y-y axis, a width orientation parallel to the x-x axis, and a depth orientation parallel to the z-z axis. The x-y-z axis for purposes of the present invention is defined with respect to an external tissue surface, which in the case of skin52is the outer surface. References to a vertical and horizontal planar orientation in connection with the present invention are made with respect to the external tissue surface at the site of the opening in question. The vertical inner surfaces60formed by each side of the opening50can be visualized as meeting along a generally vertical interface51. It will be understood that in the case of an opening that extends over a curved tissue surface, the corresponding horizontal and vertical surfaces associated with the opening will be defined with respect to such curved tissue surface. It also will be understood that the vertical interface51may be vertical in only one orientation with respect to the tissue surface, such as in the case when an angled incision has formed the opening50.

As is best illustrated in the sectional views ofFIGS. 2 and 3, human skin52generally has three discrete layers. These layers comprise an epidermal layer54of mostly non-living tissue having an exterior surface55, a dermal layer56of mostly living tissue, and a subcutaneous tissue layer58. Although the preferred embodiment of the present invention will be described with respect to human skin tissue52, it will be understood that the present invention is applicable to closure of openings in other types of tissue having generally defined surfaces, such as fascia, membranes organs, vessels, vasculature, vascular pedicles, skin grafts, bladder and other biocompatible materials with generally defined surfaces such as artificial skin, artificial membranes and synthetic mesh.

It has long been known that the most rapid healing of a skin opening with a minimum of scarring occurs when the inner surfaces60of the living dermal layer56at each side of the vertical interface51of skin opening50are brought together and held in close contact in what is referred to as an everted position as is shown in exaggerated fashion inFIG. 3. To the extent that the primarily non-living material of epidermal layer54can be excluded from the healing opening, the rapidity and level of scar tissue formed during the healing process will be improved.

The ability of the present invention to provide a more effective and efficacious tissue closure can be seen with reference toFIGS. 30-33, which show skin openings closed by various prior art methods as compared with an opening closed using the bilateral fastening techniques of the present invention. InFIG. 30, there is shown a skin opening closed with subcutaneous sutures. The generally everted condition of the closed opening can produce unattractive scarring and less than optimal healing if the eversion is excessive or inadequate. As can be seen fromFIG. 30, obtaining consistency from suture to suture is difficult and the quality of the closure is highly dependent upon the skill of the surgeon.FIG. 31shows a skin opening closed by conventional surgical stapling. In addition to the generally unattractive appearance of the closed opening, staple openings and the excessive everted condition of the opening may lead to undesirable scarring. In addition, if non-resorbable staples are used, the staples must be removed before complete healing can occur.FIG. 32shows a depiction of an opening closed with the interdigitated subcuticular stapler known as the SQS device that is described, for example, in U.S. Pat. Nos. 5,292,326, 5,389,102, 5,489,287 and 5,573,541. The characteristic undulating appearance caused by the overlapping interdigitation of the skin may lead to an unusual appearing scar in the healed opening. The overlapping and interdigitation of the skin can also cause epidermis tissue to be interposed between dermal layers, thereby leading to incomplete healing or excessive scarring.

By comparison, an opening that has been partially closed by the method and using the apparatus of the present invention is shown inFIG. 33. As shown, the closed portion of the opening is tightly closed, yet lies flat without undue eversion of the opening leading to better healing performance with minimal scarring. There is consistency in the closure from fastener to fastener. Because the fasteners are positioned below the skin surface (i.e., subcuticular), the fasteners are not exposed and there is no puncturing or button-holing of the epidermis that can lead to the increased possibility of infection or interference with the normal healing process. In addition, if fasteners made of a bioresorbable, bioabsorbable or even a bioerodible material are used, there is no need to later remove the fasteners.

The advantages of the present invention are accomplished by an apparatus and method that bilaterally engages target tissue zones70on each side of a skin opening50with a fastener that is preferably made of a bioresorbable material. As used in connection with the present invention, the term bilateral refers to at least two axis of insertion for a fastener that are on separate sides of the vertical interface51of an opening50. The bilateral engagement may be made either simultaneously or sequentially, and the fastener used may have a variety of configurations and be oriented in a variety of ways as will be further described herein. The location, geometry and orientation of the fastener and the dermal layers in relation to the mechanical apparatus of the present invention are all important considerations to obtaining the most optimal contact and compression of the dermal layer for efficacious closing of the opening. While the skin opening50will be described in connection with an opening in a single piece of tissue, it will be understood that the opening50could also be between two separate and otherwise unconnected pieces of tissue, or even between a piece of tissue and a piece of biocompatible material to be secured to that piece of tissue.

As is shown inFIGS. 4 and 5, there exists an optimal target tissue zone70on each side of vertical interface51that may be bilaterally engaged by a fastener in order to achieve optimal dermal contact for healing. This target tissue zone70lies within the dermal layer56, and can be visualized as a rectangular cross-sectional area when the tissue is in a relaxed condition as shown best inFIG. 4. In addition, within target tissue zone70, there exists a most preferred area72for tissue engagement. In the depth orientation, target tissue zone70lays between a distance L3of about 0.1 mm below the surface55of epidermal layer54, and a distance L4up to 2.0 mm below the surface55. The most preferred area72lies between a distance L5of about 0.2 mm and a distance L6of about 0.8 mm below the surface. In the width orientation, target tissue zone70lies between a distance L7of about 1.0 mm and a distance L8of about 20.0 mm from vertical interface51. Most preferred area72lies between a distance L9of about 2.0 mm and a distance L10of about 8.0 mm from vertical interface51. Because the target tissue zone70is not visible to an operator, the manipulator assembly400and applicator assembly100are preferably designed to consistently and repeatedly enable the operator to position the target tissue zone70for deployment of a fastener400.

As illustrated inFIG. 6, due to the inherent flexibility and resilience of skin tissue, it is most desirable that a fastener400be deployed into the target tissue zone70while the skin opening is everted. By compressing the everted dermal layers56on either side of the opening50into the fastener400, the dermal layers56are retained in close contact with each other by the fastener400after the everting pressure is removed and the skin relaxes into a flat condition as shown inFIG. 4.

A preferred embodiment of the apparatus of the present invention is shown inFIGS. 7-20. Generally, the apparatus includes an applicator assembly100, a tissue manipulator assembly300, and a fastener400.

A preferred embodiment of applicator assembly100is shown inFIGS. 7-16. The assembly generally comprises upper handle portion110and lower handle portion120, to which is attached driving head140. Trigger200, which pivots about pivot202is provided to allow user actuation of the mechanism. Although a manual pivoting trigger arrangement200is shown, it will be understood that a variety of other user-actuated manual triggers, buttons or actuator mechanisms may be utilized with the applicator assembly100, such as a push button, slide mechanism, cam mechanism, spring actuated apparatus, cable actuated pull mechanism, rotating mechanism or tab actuated trigger. Alternatively, an automatic actuator in the form of an electronic, pneumatic, motion controlled, remote controlled or computer-activated trigger may be used to operate the applicator100.

InFIGS. 8-13, there are shown detailed views of a preferred embodiment of a driving head140and lower handle portion120. Driving head140is preferably U-shaped and has an anvil portion142separated from backing portion144by a cross-member146, thereby forming a gap148. Cross-member146preferably has concave areas150, which are shaped to correspond to tissue manipulator surfaces318of tissue manipulator assembly300, allowing the dermal layer56of skin to be compressed into contact within gap148, and with target tissue zones70present for capture on either side of vertical interface51as will be further explained hereinbelow. Although driving head140is shown in a fixed orientation relative to lower handle portion120and upper handle portion110, it will be understood that driving head140may be articulated, either in the plane of the vertical interface51or perpendicular to the plane of the vertical interface51, to allow for increased maneuverability and orientation of driving head140. Alternatively, lower handle portion120may be articulated relative to upper handle portion110, or both lower handle portion120and driving head140may be articulated.

Preferably, anvil portion144of driving head140has apertures152formed therethrough. Apertures152are appropriately sized so as to slidingly receive penetrators or pilot needles154,156and may be bore directly into the material of anvil portion144or may be lined with a metal guide tube or the like inserted into a bore in anvil portion144. Pilot needles154,156have a generally arcuate shaped cross-section throughout distal portions155,157, and a solid cylindrical cross-section in proximal portions159,161. Each distal portion155,157has an inner concave surface158,160for accommodating and retaining a fastener400, and each proximal portion159,161engages the back surface of the fastener400, allowing the fastener to be advanced distally with the needles. The distal ends162,164of pilot needles154,156have a sharp point for penetrating skin. Pilot needles154,156are vertically disposed at a distance d1 below top surface166of anvil portion142. It is preferable that top surface166be usable as a reference datum for visually gauging whether pilot needles154,156are located within target tissue zone70. Accordingly, it is preferable that distance d1 be between 0.1 mm and 2.0 mm, and most preferably between 0.2 mm and 0.8 mm, so that when top surface166is aligned with the outer skin surface, pilot needles154,156are located within target tissue zone70and most preferably within most preferred area72.

Delivery mechanism128serves to eject a fastener from driving head140. In a preferred embodiment, slide block122is slidably mounted on guides124,126, within lower handle portion120. Slide block122is engaged with trigger200so that actuation of the trigger causes sliding movement of slide block122. Pilot needles154,156are fixedly attached to slide block122, and extend outwardly through backing portion144of driving head140through slot168. Thus, back and forth sliding motion of slide block122causes pilot needles154,156to be extended and retracted from slot168, gap148and apertures152. It will be understood that any number of mechanical driving arrangements can be used to impart the necessary force to pilot needles154,156, or alternatively to the fastener400directly. Examples include sliding mechanisms, cam mechanisms, spring-operated mechanisms, screw drives, pneumatic drives, automated motion control drives, or the like.

Pilot needles154,156are preferably spaced apart by an interneedle distance of between about 2.0 mm and 20 mm and most preferably between about 4.0 mm and 16.0 mm, so that when the driving head in placed within a skin opening to be fastened, and with the skin opening aligned with the approximate midpoint between the pilot needles, the pilot needles will be located within the width orientation of the target tissue zone70.

Although single fasteners may be inserted manually one-by-one between pilot needles154,156, an alternative embodiment of applicator assembly100, shown in phantom inFIGS. 14-16, has an automated fastener delivery and storage mechanism220. In this mechanism, fasteners are preferably stacked vertically in echelon fashion surrounding a guide member224, and are biased downwardly with a resilient member such as a spring (not shown). Housing222is provided to protect the mechanism. The bottom-most fastener in the echelon is engaged with pilot needles154,156. As each fastener400is emplaced in the skin through operation of the applicator assembly100as described herein, and slide block122is returned to the proximal limit of travel, the downward bias of the echelon causes the immediately vertical adjacent fastener to move downward and become engaged within pilot needles154,156. The next fastener may then be emplaced in the skin, and the process repeated. Again, it will be appreciated that numerous arrangements and configurations for providing and deploying multiple fasteners within the context of the present invention could be used, such as inline stacking in either a horizontal or vertical orientation, side-by-side stacking, rotational presentation via a circular chamber or magazine or belt or tape-attached presentation of the fasteners400.

InFIGS. 17 and 18, there is shown a preferred embodiment of the tissue manipulator assembly300of the present invention. The proximal ends307of arms302,304are joined together at fulcrum306, forming the tweezer-like structure of the overall assembly. Gripping areas312are provided on each arm to allow gripping of the assembly with the fingers. Any suitable fastening method may be used at fulcrum306, including rivets316as shown, or the arms302,304may be welded, cast, or molded together or may otherwise be integrally formed together. The material and overall dimensions for arms302,304are selected so as to allow the arms to be resiliently compressed inwardly with the fingers, and with a memory characteristic for returning to the original position upon the removal of pressure. In addition, the material used for the arms and other portions of the assembly are preferably thermally and chemically stable so as to allow sterilization with either heat or chemical means. The preferred material for arms302,304is stainless steel.

At the distal ends309of each arm302,304are formed tissue manipulator surfaces318. Manipulator surfaces318are preferably semi-cylindrically shaped as shown, with the diametrical dimension of each semi-cylinder selected so as to conform to the diameter and shape of the concave areas150of applicator assembly100. Skin gripping jaw members314are preferably attached to the exterior surfaces326of each arm member302,304. Each jaw member314has a backing portion324for attaching to the arms, and a pair of inwardly directed projections320disposed on both sides of manipulator surfaces318. Directly opposed serrations322are preferably provided on the inward-most edge of each projection320for better skin purchase. Backing member324may be attached to each arm302,304using any suitable attachment method, including mechanical fasteners such as the rivets316as shown. For reasons that will be further explained, it is preferable that each jaw member314is of sufficient resilience and is attached so that inwardly directed projections320may deflect separately from skin manipulator surfaces318under moderate finger pressure applied to arms302,304. This may be achieved through concerted selection of the material used for jaw member314, the thickness dimension of backing member324, and the free length L1of each backing member324between the inwardly directed projections320and the fastener316closest to the distal end309of the arm. The objective of the design of the backing member324is to have the jaw members314engage tissue with a first force and have the manipulator surfaces318engage tissue between the jaw members314with a second force that is greater than the first force. In addition, the use of a pair of directed projections320on each side of the vertical interface51serves to stabilize the tissue laterally between the pair of projections320.

Mechanical stops330are provided to prevent pressure beyond that necessary to ensure optimal approximation of tissue into gap148and concave portions150of applicator assembly100from being transmitted through manipulator surfaces318. Preferably, mechanical stops330are set so that manipulator surfaces318close to a distance that is spaced apart from the interneedle distance of pilot needles154,156by a range of 0.2-0.8 millimeters, such that the total distance between mechanical stops330is 0.4-1.6 millimeters greater than the interneedle distance between pilot needles154,156. In a preferred embodiment in which the interneedle distance is set at 3.25 millimeter, the mechanical stops330would allow the surfaces318to close to within a range of 3.65-4.85 millimeters when approximating tissue into gap148. Although jaw members314may be formed from any suitable material, the preferable material is stainless steel.

InFIGS. 19 and 20, there is shown a preferred embodiment of a fastener400of the present invention. Fastener400has body portion402, which comprises a cross-member408connecting a pair of fork members or legs406. The outer margins410of each leg406are dimensioned and shaped accommodatingly to the inner concave surfaces158,160, of pilot needles154,156, allowing fastener400to fit and slide between the distal portions155,157of the needles, as is shown best inFIGS. 12 and 13. Shoulders414preferably are provided to engage the solid cylindrical cross-section of the proximal portions159,161of pilot needles154,156, thus allowing fastener400to be advanced distally with motion of the needles. The distal end412of each leg406is incurvately shaped to allow easier passage through an opening in skin, referred to as a skive, that is created by pilot needles154,156. Inwardly directed barbs404preferably are provided on each leg406to resist withdrawal of the fastener once emplaced.

Although an overall U-shape for the fastener400, as shown inFIGS. 19 and 20is preferred, other shapes having a capability for bilateral tissue engagement are also possible and within the scope of the invention. Such other shapes include for example, but are not limited to, a square shape similar to an ordinary staple, a semi-circular or C-shape or a V-shape or W-shape in which the cross-member408has bends or other features. While the shape of fastener400is generally determined in a planar configuration, it will be recognized that other non-planar shapes and configuration can be used, such as a fastener having multiple projections for each leg406, with each projection oriented in a different plane, or a fastener having cross-member408arranged in a V-shape projecting out of the normal plane of the fastener400. Two leg members406are preferred, but it will be understood that additional leg members406could be added in the same or a different plane of the fastener400such that the leg members of each side of the fastener form a dident or trident configuration, for example.

As shown inFIG. 39, an inner cross-sectional area409is defined by the fastener400for capturing the compressed dermal tissue. In a preferred embodiment, inner cross-sectional area409ranges from 1.5 sq. mm to 50 sq. mm and most preferably about 5 sq. mm to 10 sq. mm. This area is generally defined by an inner diameter length of between 1.5 mm and 9 mm and most preferably about 3.8 mm and an inner diameter width of between 1 mm and 5 mm and most preferably about 2 mm. It will be apparent that numerous shapes and configurations can be used for the shape and arrangement of cross-sectional area409. Preferably, inner cross-sectional area409is generally arrowhead shaped as a result of the positioning of the barbs412. As will be described, the barbs412or similar anti-reversing projections resist against the withdrawal of fastener400. While the barbs412are preferably oriented into the inner cross-sectional area409, it will be appreciated that barbs412may be omitted or may be oriented outwardly.

Although it is possible for fastener400to be deformed during delivery and application, preferably the majority of dermal tissue retained within cross-sectional area409is captured in a compressed state by a fastener400that is sufficiently rigid so as to retain the dimensional integrity of cross-sectional area409within +/−30% of its designed area for a period of preferably at least 10 days. Most preferably, structural integrity of fastener400is maintained for at least 21 days. In this way, the dermal tissue captured in fastener400is retained in a compressed state for a period sufficient to allow the biological healing process to occur without the dermal tissue being under tension during the healing process. Preferably, the dimensions of the fastener400and the operation of the applicator assembly100coordinate to create a compression ratio of dermal tissue within the inner cross-sectional area409that is greater than one. The compression ratio is defined either as a ratio of area or a ratio of width. In the case of width, the compression ratio is the ratio of the dimension defined by the position of the skive relative to the vertical interface51when the dermal tissue is at rest divided by the position of the skive relative to the vertical interface as held by the fastener400. In the case of area, the compression ratio is the ratio of the area of dermal tissue that will be retained by the fastener400when that dermal tissue is at rest divided by the actual cross-sectional area409.

Alternatively, it is possible to take advantage of the bilateral tissue fastening in the tissue target zone as taught by the present invention with a deformable fastener where the deforming of a bioresorbable or bioabsorbable fastener serves to provide at least some of the compression of the dermal tissue such that the need for a mechanical tissue manipulator is reduced or potentially eliminated. In this embodiment, a bioresorbable or bioabsorbable fastener would be deformed by the applicator apparatus in order to appropriately compress the dermal tissue. Deformation of a bioresorbable or bioabsorbable fastener could be accomplished in a number of ways, including pre-stressing the fastener into an open configuration such that it returns to a closed configuration, with or without mechanical assistance from the applicator, application of ultrasound, heat or light energy to alter the shape of, or reduce or relax stresses in, the fastener in situ, designing a polymer material with appropriate shapes and compositions that the material is deformable upon deployment without fracturing, or any combination of these techniques.

Fastener400is preferably formed from any suitable biodegradable material. The currently most preferred biodegradable material is a lactide/glycolide copolymer where the ratio is never less than at least 10% of one element and preferably in a range of 60%-70% lactide. Examples of other suitable materials include poly(dl-lactide), poly(l-lactide), polyglycolide, poly(dioxanone), poly(glycolide-co-trimethylene carbonate), poly(l-lactide-co-glycolide), poly(dl-lactide-co-glycolide), poly(l-lactide-co-dl-lactide) and poly(glycolide-co-trimethylene carbonate-co-dioxanone). In addition, other suitable materials could include compositions with naturally occurring biopolymers such as collagen and elastin, or stainless steel, metal, nylon or any other biocompatible materials in the case of a non-absorbable fastener, or even various combinations of such materials depending upon the desired application and performance of the fastener.

With reference toFIGS. 21-24, the operation of the apparatus of the present invention may now be explained and understood. A fastener400is first loaded between pilot needles154,156, as shown inFIG. 12. Slide block122is then proximally retracted to the fullest extent so that pilot needles154,156and the fastener400are entirely within slot168. Driving head140is then introduced into skin opening50and top surface282is aligned with the outer surface of the skin as shown inFIG. 21. Tissue manipulator assembly300is placed with jaw members314on either side of driving head140. Arms302,304of manipulator assembly300are pressed inward so that jaws314engage the skin surface and begin to force the skin52into gap148in applicator assembly100as shown inFIG. 22. Serrations322provide purchase on the skin surface and prevent lateral slipping of the skin relative to the jaws. As further inward pressure is applied to arms302,304, inwardly directed projections320engage side surfaces170of anvil portion142and side surfaces172of backing portion144, each with a single thickness of skin trapped between as shown inFIG. 23. Still further inward pressure on arms302,304, as shown inFIG. 24, causes tissue manipulator surfaces to deflect inward slightly from jaws314, until each engages concave area150of cross-member146with a layer of skin trapped in between. In this position, inner surfaces60of dermal layer56are in direct contact with each other within gap148and substantially parallel with vertical interface51, but are not overlapped or interdigitated.

In this preferred embodiment, pilot needles154,156are aligned generally horizontally and substantially parallel with the outer surface of the skin and are within target tissue zone70. Cross-member408of fastener400is positioned generally transverse to vertical interface51and a working plane of fastener400defined by cross-member408and legs406is generally horizontal in orientation. Trigger280is then actuated, causing slide block122to move proximally within lower handle portion120, and advancing pilot needles154,156into the skin, creating a skive through the target tissue zone70of the skin on each side of vertical interface51. Fastener400moves with pilot needles154,156, and each leg406of the fastener400is simultaneously driven into and through the skive. Once fastener400is advanced distally a sufficient distance so that barb tips416of fastener400enter apertures152and accordingly emerge from the skive, trigger280may be reversed so that slide block122moves proximally, retracting pilot needles154,156. Barbs412engage the skin, thereby preventing fastener400from being withdrawn with the pilot needles. Once slide block122has been fully retracted proximally, thereby causing pilot needles154,156to be fully retracted from gap148, the pressure on manipulator assembly300may be released and applicator assembly100can be moved proximally in the opening50to deliver another fastener400or can be removed from opening50.

In addition to the preferred embodiment of the apparatus described above wherein the legs of a fastener are simultaneously driven through the target tissue zone on each side of the skin opening and with the fastener legs oriented parallel to the epidermal skin surface, those of skill in the art will appreciate that other embodiments of a mechanical fastening system for openings in skin tissue are within the scope of the present invention. For instance, the working plane of fastener400defined by cross-member408and legs406may be oriented generally orthogonal, or oblique in at least one orientation, to the horizontal plane generally defined by exterior surface55of epidermal layer54. In such an embodiment, fastener400may be inserted in a generally vertical orientation with legs406pointing generally in an upward direction or in a downward direction.

Another embodiment of the apparatus of the present invention wherein a fastener is driven sequentially through the bilateral target tissue zones is shown inFIGS. 25-29. In one embodiment, fastener500has flexible body portion502with a barb506at distal end505and an attachment flap504at proximal end503. Flexible body portion502is dimensioned so as to be received within either concave inner surface158,160of pilot needles154,156. Attachment flap504has slot508formed therethrough, which is adapted to receive barb506. In applicator assembly100, anvil portion142has concave deflector153formed between apertures152and extending into a portion of each aperture152so that only an area of each aperture is open sufficient to allow the arcuate cross-section of pilot needles154,156to pass. In operation, and with reference toFIGS. 1-29, fastener500is axially aligned with pilot needle154, and is inserted within the corresponding concave inner surface of the needle with barb506oriented toward the point of the needle. Applicator assembly100is then introduced into the interface portion51of the skin opening50as described above. Tissue manipulator assembly300is then applied as before to bring the dermal layer56into contact within gap148, and thereby properly positioning target tissue zone70. As slide block122and the attached pilot needles154,156are moved distally through actuation of trigger280, fastener500is advanced through the skin tissue on one side of skin opening50along with pilot needle154in which it is disposed. Once the tip of barb506reaches aperture152, however, it is engaged by, and begins to slide laterally along, concave deflector163, causing flexible body portion502to bend. As pilot needles154,156are further advanced, barb506is turned in direction 180 degrees by deflector163. It will be appreciated that the barb506may either be positioned in front of pilot needle154by an amount sufficient to redirect barb506into the opposite direction or pilot needle154may advance into the corresponding aperture152to a depth at which the redirection of barb506upon the entry to aperture152will be sufficient to redirect barb506into the opposite direction. Once redirected and positioned in line with the second skive, barb506is advanced in the opposite direction by pilot needle156and through the skin tissue on the opposite side of the vertical interface51as pilot needle156is withdrawn. Once barb506emerges from the dermal tissue, attachment flap504may be bent so that barb506may be pushed through slot508, thus securing fastener500in a loop and bilaterally capturing both sides of the skin opening50. It will also be appreciated that attachment flap504may be replaced by suitable structure on flexible body502for engaging a suture. The suture lock of co-pending application entitled “SUTURE LOCK HAVING NON-THROUGH BORE CAPTURE ZONE,” application Ser. No. 10/166,161, filed Jun. 10, 2002 which is commonly owned by the assignee of the present invention and the disclosure of which is hereby incorporated by reference, may then be used to secure the suture to barb506, completing the bilateral capture. In this embodiment described herein, the skives are created simultaneously and the fastener400is inserted sequentially into each corresponding skive from an opposite direction. Alternatively, a single U-shaped needle could be utilized in place of pilot needles154,156and both the skives and fastener could be created and inserted sequentially. Numerous other combinations of bilateral creation of skives and insertion of fasteners are contemplated by scope of the present invention.

As described herein, the fastener is oriented so that a working plane defined by the flexible body502of fastener500is substantially parallel to a plane generally defined by exterior surface55of epidermal layer54, and transverse to vertical interface51. Those of skill in the art will appreciate, however, that the working plane of fastener500could also be oriented substantially orthogonal, or oblique, with the plane generally defined by exterior surface55while remaining in a transverse orientation with respect to vertical interface51. Those of skill in the art will also appreciate that other bilateral capture mechanical fastening systems wherein the target tissue zones are penetrated by a fastener in sequential fashion are possible within the scope of the present invention. For instance, a semi-circular, oval, or spiral fastener may be advanced sequentially through target tissue zones70on each side of vertical interface51using a mechanism that imparts a rotational motion to the fastener, but without causing interdigitation or overlapping of skin across vertical interface51. The mechanism may have means for creating a semi-circular, oval or spiral skive through which the fastener may be advanced, or the fastener itself may be formed from sufficiently rigid material and have a sharpened point so as to be capable of creating a skive as it passes through the skin. In another alternative embodiment providing a sequential bilateral capture motion, a fastener is provided having a cross-member connecting two legs wherein the legs are staggered so that when the fastener is advanced into the skin in a linear fashion, one of the legs precedes the other. In still another embodiment, two straight fasteners comprising a shaft portion with skin-engaging barbs are provided. These fasteners are oriented in opposite directions on either side of the vertical interface51, and are sequentially advanced through respective skives by an applicator assembly allowing a reversible motion.

In one embodiment, as shown inFIG. 34, a tab or other similar guiding structure167projects from an exposed portion of anvil portion140to serve as a reference guide to locating the external surface of the skin against such guiding structures. Most preferably, this guiding structure167is adapted to mate with a corresponding pair of surface guiding features169on the internal surface of arms302,304of the tissue manipulator assembly300so as to provide both a tactile and visual indication of the appropriate positioning of the applicator100and tissue manipulator300relative to the vertical interface51of the tissue opening50. Preferably, the guiding structure167and guiding features169combine to force the applicator100to stay laterally centered about the vertical interface51and to stay properly positioned both horizontally and vertically. Alternatively, visual indicators and/or an exterior platform-like structure around the exterior of driving head140may be provided to assist the user in proper positioning of the applicator assembly100and the tissue manipulator assembly300.

FIGS. 35 and 36show an alternate embodiment of applicator assembly100and tissue manipulator assembly300in which both manipulator surfaces318and concave areas150are semi-spherically shaped to provide guiding structure in both horizontal and vertical orientations as the tissue is compressed by the tissue manipulator300into the applicator100. In this embodiment, there are no inward projections320shown for capturing the tissue as the application of pressure to the ball-like tips318provides both the capture and compression forces imparted to the tissue. Areas150on the applicator100are semi-spherical in shape to mate in more than one orientation with the ball tips318, rather than being merely concave to align the tissue in a single orientation.

FIG. 37shows another alternate embodiment of applicator assembly100in which the fasteners400are inserted obliquely into the tissue along the vertical interface51. In this embodiment, the penetrating needles152,154are oriented obliquely downward relative to the horizontal and the distance dl on the driving head140is reduced. An upper projection167extends on top of the vertical interface51of the opening50to serve as a guide and the aperture141between upper projection167and the driving head140is positioned to require less rotational movement of the applicator assembly100in the plane of the vertical interface51when the tissue is being positioned in the driving head140or the applicator assembly100is being positioned for insertion of a subsequent fastener400. One advantage of the oblique orientation of the fasteners400along the vertical interface51of opening50is that the effective spacing between backing members408of adjacent fasteners400is reduced, thereby affording the opportunity to increase the resulting holding pressure that can be applied across the vertical interface51to resist tearing by being able to insert more fasteners per longitudinal distance of the opening50.

FIG. 38shows another embodiment of the present invention in which the tissue manipulator300and the applicator assembly100are integrated together into a single handheld surgical instrument600. In this embodiment, a manual trigger200is used to activate first the lateral compression operation of the arms302,304of the tissue manipulator assembly300and then is further depressed to engage the delivery mechanism128. A force translation mechanism602inside the handle110in the form of a cam, wedge or similar arrangement is first engaged by the depression of the trigger200. Further depression of trigger200then causes delivery mechanism128to be actuated. It will be appreciated that a single handheld surgical instrument600integrating the structures of both the applicator assembly100and the tissue manipulator assembly300could be arranged and operated in a number of ways. For example, two trigger actuators could be used instead of one two-stage actuator. Instead of arranging the tissue manipulator assembly300and the applicator assembly100inline in the same orientation, the two assemblies300and100could be arranged to face each other in the longitudinal orientation.

Although the present invention has been described with respect to the various embodiments, it will be understood that numerous insubstantial changes in configuration, arrangement or appearance of the elements of the present invention can be made without departing from the intended scope of the present invention. Accordingly, it is intended that the scope of the present invention be determined by the claims as set forth.