APPARATUSES, SYSTEMS, AND METHODS FOR FASCIAL CLOSURE

A biocompatible device for fascial closing following surgeries and a corresponding hand-held tensioning mechanism. The device is modeled after a zip tie and consists of a needle, body, and locking mechanism. The needle and body are driven through fascia, then the needle is separated to allow for the feeding of the body through the locking mechanism to provide tension against fascia separation. The body of the tie comprises a first face with a series of recessed teeth and a second face with a substantially smooth surface. When the tie forms a loop in a locked configuration, the first face of the body is oriented toward an internal volume of the loop and in direct contact with a target, whereas the second face of the body is oriented towards surrounding tissues that minimizes trauma to surrounding tissues.

TECHNICAL FIELD

Embodiments described herein relate to internal fixation devices, including fasteners and fixators. Such fixation devices and systems can include flexible bands or straps.

BACKGROUND

The foundation of good wound closure starts with a good fascial closure. Fascia is a band of connective tissue beneath the skin that attaches, stabilizes, and separates organs and skin within the body. The most prevalent method used to achieve fascial closure is by hand tying sutures along the length of the wound. Unfortunately, complications occasionally exist associated with poor closure of the galea, even in the most skilled of hands. These complications can include wound dehiscence, muscle retraction, herniation, poor cosmetic wound healing, protruding knots, and a route for deep wound infections. Complications become more likely in patient populations that undergo frequent repeat operations (e.g., trauma, oncology, shunted hydrocephalus). For these patients, the fascia typically is lost to scar tissue formation and the overlying skin thins, increasing the difficulty to achieve a robust closure. Sutures placed in the location of the fascia are prone to “pulling through” when tension is applied. This term refers to what occurs when the sutures break through the hole punctured in the fascia before bringing each side together. Alternative suturing techniques, such as full thickness vertical mattress sutures, can be used in some circumstances to close these friable tissues, but these alternatives increase operative time and are of questionable benefit. Regardless of the complexity of a wound, all sutures must be tied to a similar tension. If there is too much variance in tension between sutures, sutures under high tension are prone to breakage or early loss of tensile strength. This leaves a segment of the wound susceptible to wound dehiscence due to the loss of the integrity provided by the underlying fascial closure.

It is often the case that a fascial suture is tightened as much as possible by a medical practitioner, to the point that the suture is on the verge of breaking. Different types of suture material are used for different purposes, such as braided or monofilament fibers having different cross-sectional areas for varied surface characteristics and tensile strength. Additionally, it may be necessary to apply sutures to pull together the edges of an incision by an initial amount, and then later in the same procedure re-tie the sutures or add new sutures to pull the edges closer together. This reduces the force that is needed on the suture in the first pass, and therefore reduces the hand strength needed by the medical professional and reduces the possibility for injury caused by the suture material itself pulling on the patient. In general, the manual nature of the suture tying leaves patients vulnerable to human variation.

Fascial sutures are placed via a repeatable process one at a time. First, the needle is grasped by the needle driver on the needle body. Once the tissue being driven into has been stabilized with forceps, the needle is penetrated through the tissue at an approximately 90° angle typically between 1-3 mm from the fascia edge, depending on the thickness. Next, the needle and suture are pulled through the puncture hole and the needle penetrates the other side of the wound perpendicular to the fascia, on the other side of the wound. The surgeon then brings the tissue together by pulling on either side of the suture, applying the tension by hand. Once the surgeon is satisfied with the degree of closure, they place a knot to secure the suture and lock the tissue in place. Multiple knots are often thrown to ensure reliable locking. The process can take up to 30 or 40 minutes for some procedures.

Cable ties, sometimes referred to as zip ties, are commonly used flexible fasteners that consist of a notched body with a locking mechanism on one end that the other end of the body can be looped through. As the body is pulled through the locking mechanism, small notches/teeth within it match the geometry of the body's notches, and engage to ratchet the body through, preventing reverse motion beyond the most recent tooth to pass through the ratchet. Pulling the body through tightens the zip tie loop and can be done by hand, or with a zip tie tensioning device which can tighten the zip tie to a desired degree of tension and cut the excess zip tie material flush with the locking mechanism.

Cable ties have been disclosed for use with bone or cartilage, such as in U.S. Patent Publication No. 2013/0261625 to Koch. The ties disclosed in Koch provide ratcheting mechanisms and are shaped to correspond to the boney structures that they wrap around. The tensioning device for a cable tie, which is often shaped like a gun and referred to as a “zip tie gun,” requires the user to pull a trigger that ratchets the zip tie tight around an object. This is a knotless securing method with little to no tension variance between ties, ensuring a uniformly tight closure. The notch engagement design, which only allows translational movement forwards through a lock to increase and hold tension has been emulated in a few surgical closures, such as those described in U.S. Pat. No. 7,972,347 B2 to Garvin and U.S. Pat. No. 9,757,131 to Sanders. Garvin describes a single piece surgical wound fastener that clasps with a male connecting strap and female connector to be bidirectionally ratcheted with a clamp to tighten the wound closure. The device is directed to be affixed to the tissue directly on either side of the wound with barbed insertion tongues and intended to provide even tensioning. Sanders describes a strap tie assembly ratcheting via a plurality of engagements in a receiving channel which is affixed from large bases attached directly to the skin with barbs or hooks. Other ratcheting devices for attachments to bone are described in, for example, U.S. Pat. No. 8,845,686 to Bennett and the related commercial products sold by ZipTek LLC.

The cable ties described in Koch, Garvin, Sanders, and Bennett are not suitable as suture replacements for a variety of reasons. First, sutures should not need to be removed in the majority of applications. That is, sutures typically dissolve in the body in about the time it takes for the incision to heal (or longer). Otherwise, it would be necessary to reopen the incision to remove the sutures, which would defeat the purpose of the procedure. For that reason, ties that are used for connecting bone are not usable for tissue repair such as sutures for the fascia. For example, Koch describes use of PEEK or PEKK, neither of which would dissolve, while Bennett uses metallic screws for anchoring. While the structures and materials of these references are therefore suitable for bone and cartilage procedures, they cannot be incorporated into a tissue repair application.

Patients who have wounds closed poorly or have pieces of the closure device remaining may experience poor wound closure, wound dehiscence, muscle retraction or spasms, herniation, and cosmetic problems. Additionally, remaining material can provide a route for deep infections. Therefore it is important to properly close a wound, preferably using the least amount of time and leaving little to no material behind (such as by using dissolvable materials).

SUMMARY

The systems, devices, and methods described herein add ratcheting functionality for tissue repair. This reduces the time needed to carry out a procedure, is safer and more comfortable for physicians, reduces or eliminates the chance for breakage of the suture, and permits tightening and re-tightening of the same ties. The ties disclosed herein have a variety of shapes in different embodiments that are relatively low-profile and that will provide adequate holding strength for an incision to repair itself, while also being dissolvable for long-term patient safety and comfort.

According to an embodiment, a tie is made of a biodegradable material. The tie includes a body extending a long a length from a proximal end to a distal end, a needle coupled to the body at the distal end, and a locking mechanism. The locking mechanism is coupled to the body at the proximal end and oriented to receive the distal end of the body, such that the body can be pulled through the locking mechanism to create a loop. The body includes a series of recessed teeth defined within an otherwise smooth form factor, wherein each tooth of the series of recessed teeth includes a base and an apex, with the base extending into the body and the apex flush with a top face of the body defined by the form factor, such that each tooth has a cross-section in the shape of a right triangle, and wherein each tooth faces inwards when the body is arranged in the locking mechanism to form the loop.

According to another embodiment, a tie is made of a biodegradable material and includes a body extending a long a length from a proximal end to a distal end, a needle coupled to the body at the distal end, and a locking mechanism coupled to the body at the proximal end and oriented to receive the distal end of the body, such that the body can be pulled through the locking mechanism to create a loop, wherein the body comprises ramp extrusions that make up a series of teeth each having a triangular cross-section, wherein a width of each tooth is equal to a width of the tie, and wherein each tooth faces inwards when the body is arranged in the locking mechanism to form the loop.

In either of the first two embodiments, the locking body can define a receiving channel, and wherein the receiving channel is configured to receive the body. The tie can include a locking engagement arranged in the receiving channel and responsive to an applied force of a tie passing through to bend from a hinge towards the sidewall of the lock, wherein the locking engagement is configured to mate with the teeth with a responsive force, fully grasping a tooth and restricting translational movement backwards through the receiving channel. The extension of the locking device beyond a closure site can be minimized. The body can be passed through the lock is ratcheted to hold a target tension.

The biodegradable material can be biocompatible and bioabsortive in a body over a target time period. The biodegradable material further can be a compositional mixture of PLA and PLGA from 0:200 to 200:0. The material can enable the tie to be closed to form a loop of a target diameter. The needle can further have a diameter, an inner radius, and an outer radius, wherein the diameter is equal to or greater than a width of the body, the inner radius configured to match a bottom face of the body, and the outer radius configured to match with a teeth side of the body.

The material can enable the zip-tie to be cut with standard Operating-Room scissors. The tie can have a surface area configured to be directly applied against the body and better supports surgical closure. The tie can be used for surgical closure in a procedure such as to stitch through fascial layers; to perform spinal closures to support the high tensile strength and force needed to hold closed the wound; cranial closures; laparoscopic surgery; endoscopic surgery; to stitch bones together; sternum closure in open heart and other applicable surgeries; and emergency situations and applications by the military.

According to another embodiment, a method for surgical fascial closure includes securing a tie with surgical drivers, the tie comprising a body, needle coupled to the body at a distal end; the body extending a long a length from the distal end to a proximal end, a locking mechanism coupled to the body at the proximal end and oriented to receive the distal end of the body, such that the body can be pulled through the locking mechanism to create a loop, wherein the body further comprises ramp extrusions that make up a series of teeth each having a triangular cross-section, wherein a width of each tooth is equal to a width of the tie, and wherein each tooth faces inwards when the body is arranged in the locking mechanism to form the loop; driving the tie through fascial layers, with the surgical drivers, at a distance of X to Y from a first side of a wound, and up through the fascial layers at second side of the wound at the same distance X to Y from the wound, where X to Y are defined by dimensions of the tie used; and passing the distal end of the body through the locking mechanism.

The locking body mechanism can include a receiving channel, and the receiving channel can be configured to receive the body and is marginally larger than the body to account for a close fit. The method can include using a device having a locking engagement arranged in the receiving channel and responsive to an applied force of a tie passing through to bend from a hinge towards the sidewall of the lock, wherein the locking engagement is configured to mate with the teeth with a responsive force, fully grasping a tooth and restricting translational movement backwards through the receiving channel. The method can include using the applied force to ratchet the ties placed along the length of the wound towards closure, either one by one, or gradually, moving from one to the next until a target tension is achieved; and cutting the tie body flush with the lock at that tension. The needle can be cut off from the body of the tie before securing the tie. Securing the tie with the surgical drivers can involve securing the needle with the surgical drivers, and driving the tie through the facial layers comprises driving the needle through the facial layers.

According to another embodiment, a tie tensioning gun can be specialized for use with surgical ties. The tie tensioning gun can include an external frame encasing the internal components with an opening in the side to load a tie; a clamping mechanism for gripping the tie in the opening of the device; a handle, formed as a trigger, that is pulled to clamp and tighten the tie; and at least three internal links comprising a mechanism that translates a rotational motion, created on the handle when pulled, to linear motion.

The tie tensioning gun can further include a spring with an adjustable length to allow for cutting the tie at a predetermined tension, and a blade, wherein one of the at least three links has a proximal end and the blade is couple to the proximal end of the one of the at least three links. The blade can cut an excess of the tie when a locking mechanism on a proximal end of the tie is flush with the opening in the side of the external plastic frame. The tie tension gun can include a container configured to receive the excess of the tie when cut.

DETAILED DESCRIPTION OF THE DRAWINGS

Tissue repair, including fascia repair, relies in large part on the use of sutures that can easily break, cause injury to the medical practitioner's hands during install due to the force required, and that are time-intensive to make. Ratcheting functionality reduces the potential for injury or discomfort for the medical team, and speeds up the process of closing an incision. The total number of ratcheting bands can be reduced as compared to sutures because the bands are larger and sturdier than sutures. The bands can also have significantly higher tensile loads applied due to their increased cross-sectional area.

Unlike existing ratcheting devices such as zip-ties, in suture replacement it is beneficial to use materials that dissolve over time. The dissolving time can be pre-set by using different materials, shapes, and sizes. Additionally, the bands disclosed herein can have different sizes or cross-sectional areas to set the maximum level of tensile force that can be supported. As such, larger or stronger patients or parts of the body can have differently sized bands than smaller or weaker patients or parts of the body.

The shapes described herein reduce the time needed to carry out a procedure compared to sutures, for two reasons. First, the total number of bands needed is lower than the number of sutures that would be needed, due to the increased physical size and tensile strength of the bands compared to a surgical suture. Second, the bands can be tightened by a relatively small tightening gun, rather than requiring access for a pair of hands as is the case with sutures. Therefore more people, such as a surgeon and one or more surgeon's assistants, can be involved in the tightening process than would be possible for tightening sutures.

The devices described herein are safer and more comfortable for physicians, reduce or eliminates the chance for breakage of the closure device, and permits tightening and re-tightening of the same ties, unlike sutures. The ties disclosed herein have a variety of shapes in different embodiments that are relatively low-profile and that will provide adequate holding strength for an incision to repair itself, while also being dissolvable for long-term patient safety and comfort.

FIG.1is a detailed cross-sectional view of a fascia that can be held by devices described herein. As shown inFIG.1, a typical portion of the body that can be held with the bands described herein includes a top layer L1that is skin. The skin layer L1is arranged above adipose tissues layer L2. The adipose tissues layer L2is adjacent a layer L3of loose connective tissues that connect the skin and adipose layers L1and L2to the muscle layer L4. However, a thin layer of deep fascia is interposed between adipose layer L2and connective tissues layer L3, and it is this deep fascia that must be reconnected for proper healing after an incision.

FIGS.2A and2Bare perspective and top views, respectively, of a fastener according to a recessed-tooth embodiment. The fascia closing device illustrated inFIGS.2A and2Bis a surgical fastener, where the locking teeth are recessed into the body2. The zip tie has a locking mechanism1connected to the zip tie body2which is attached to a steel needle3.

As shown inFIG.3, the device has a smooth cross-section when the body2is viewed from the side. The smooth cross-section is due to the recessed nature of the teeth (not shown inFIG.3) into the body3. This recessed tooth structure facilitates easy sliding of the device through the fascia and other tissues without causing unnecessary trauma that a rough outer form factor could otherwise generate. Additionally, as shown inFIG.3the needle3has the largest cross-sectional width, such that pulling the body2through the opening created by the needle3should not cause any further stress on the surrounding tissue.

The zip tie body2of the embodiment ofFIGS.2A,2B, and3, as described above, has a solid body with triangular teeth recessed into it. This is shown in the detailed view of FIG.4. The teeth have a vertical component3used in accordance with the locking mechanism to stop reverse motion and slanted face4to allow forward motion through the locking mechanism. These teeth are spaced evenly5over the top face of the body2. As used herein, the term “vertical” and the like refer to the orientation on the page, and it should be understood that with respect to some other reference frame the teeth may not be vertically oriented whatsoever. In fact, as described in more detail below, the teeth may not even be oriented in the same direction as one another, as the entire device can be formed into a loop or other bent structure.

FIG.5shows a locking mechanism usable with the device described above with respect toFIGS.2A,2B,3, and4. In particular, the locking mechanism1ofFIGS.2A,2B, and3can be substantially as depicted inFIG.5.

The locking mechanism ofFIG.5has an extension6that connects the outer shell7to the zip tie body. In embodiments, the extension6can be connected to the body2by mechanical friction fit, by melting or welding the components together, or other fastening mechanisms. In some embodiments (not shown), the extension6can be significantly larger than shown and include teeth, such that the extension6is the body2. In such embodiments, it is possible for the device to be a single unitary device rather than having a locking mechanism (e.g., locking mechanism1) that is formed separately from the body2. In embodiments, a sleeve (not shown) or other structure can surround extension6to render the area around extension6smooth, rather than having sharp corners as depicted inFIG.5.

In use, as shown inFIG.6, the body (e.g., body2) can be fed through the opening in the locking mechanism8and the tongue9is the pawl of the ratcheting mechanism. The slanted back of the tongue10allows for the tongue to displace as the zip tie is pulled through the locking mechanism, then snaps back to place once the zip tie teeth align with the pawl teeth11. The pawl teeth11are spaced12equally to the teeth on the zip tie body. When the zip tie body is engaged with the pawl teeth, reverse motion is prevented by the interlocking bodies13of the teeth. The spacing between the teeth can be set based on the expected use. In some procedures it may be desirable to have more closely-spaced spacings12, while for larger incisions the spacing12could be greater. In some embodiments, smaller spacing is desirable due to the higher accuracy of desired tension that it allows. In embodiments, spacing12can be between about 0.02 inches and about 0.05 inches.

FIG.7is a cross sectional view of the body2of the recessed-style device ofFIGS.2A and2Bbeing fed through the locking mechanism to engage with tongue9, illustrating how the tongue9of the locking mechanism fits in with the device body2to prevent backwards motion. As shown inFIG.7, the interlocking bodies13of the teeth are engaged such that moving the body2upwards with respect to the page is possible, while moving the body2downward with respect to the page will cause tongue9to deform downwards and to the right, pinching the body2and preventing movement.

FIG.8is a plan view of the recessed-style locking mechanism component ofFIGS.2A and2B, illustrating the relative body size of the major components described previously.

FIGS.9-15depict an exposed-style fascia closure device according to another embodiment. The terms “exposed-style” and “protruding teeth” are used to refer to the same types of devices throughout this disclosure. Unlike the embodiment described above with respect toFIGS.2A-8, the teeth in this embodiment are not recessed. Exposed teeth15can grip to adjacent structures, including tissue, bone, or other devices.

Like the recessed device, the exposed-style fascia device ofFIGS.9-15has teeth15that rise at some slope18to a point19. Extension20(similar to extension6described above) extends outwardly from the outer shell21. Tongue23extends through an inner passage22. The tongue23can be flexible so that surface24is parallel with a wall of the inner passage22when compressed, or angled outwards (as shown inFIG.14) when not compressed.

The teeth can be made of a material17that is dissolvable in tissue so that the teeth15hold for a sufficient time for the fascia or other adjacent tissues to heal, before the structural integrity of the device is compromised due to the dissolving. In embodiments, the material can be a mix of polylactic acid and polyglycolic acid, such as a 90/10 copolymer blend. In alternative embodiments, the ratio of monomers could differ to be, for example, 999/1 to 1/999, such as about 80/20. Other monomers could be used that are soluble, such as polydioxanone, for example. In other embodiments, the material could be the same materials used currently for surgical sutures, such as VICRYL® or MONOCRYL® (poliglecaprone25) materials.

The cross-section of the devices described herein can vary based on the expected load, the material or materials used in the construction of the device, and the cross-sectional area of the device at its narrowest point. The structure of the devices can therefore be modified to have different materials and/or minimum cross-sectional areas to support the needed load, while also remaining small enough to fully dissolve on the desired timeline and to avoid being uncomfortable or noticeable in the patient after the procedure.

FIGS.16-21depict a fascia closing device having a circular cross-sectional shape according to another embodiment. A circular cross-section lacks sharp corners and edges, and can therefore be a more gentle tie for the patient. Additionally, due to the large ratio of volume to surface area, the circular cross-section will dissolve relatively slowly compared to a zip tie having another shape. Furthermore, a circular cross-section can be used easily with a more traditional needle shape (retaining a more spherical cross section). A circular cross section allows for easier bending in any direction since no bending direction has corners in the way. This allows for the tie to be placed non-perpendicularly within the incision without increased error risk from bending phenomena. Circular cross-sections can also provide more robust locking than devices in which the body must be aligned with the aperture of the locking portion.

The parts of the device shown inFIGS.16-21are similar to those of the previously-described embodiments, but modified the circular cross-section of the body. A modified locking mechanism27is configured to receive a ribbed portion28of the body. As shown inFIGS.16and17, the locking mechanism27has a necked shape and a circular socket-like shape at a proximal end thereof (wherein the distal end is opposite the ribbed portion28, at the needle29). The ribbed portions28engage with teeth25, which can be separated by gaps26.

Ribbed portion28can include a series of ridges30opposite the necked portion31from the locking portion27. The ridges can be received in an aperture32and locked in place by a deformable portion33, as shown inFIG.20. In various embodiments, the locking portion can be entirely internal to the locking mechanism, or it can partially or entirely protrude from the locking mechanism.

It should be understood that additional cross-sectional shapes could be appropriate for other embodiments. As described above, flat rectilinear ties and those with circular cross-sections are usable in a large number of embodiments. However, it may also be desirable to use ties that have a cross-sectional shape suitable for other purposes or locations within the patient.

FIGS.22and23depict a side-loaded embodiment, which can have a reduced profile as shown in the top view ofFIG.23. As shown inFIG.22, a locking mechanism35is coupled to a proximal portion36and a distal portion37that can be locked therein. The distal portion37is coupled to a needle38. A closed loop can be formed with very low profile and without a sharp angle between the body and the body itself. In embodiments, the proximal portion36and the distal portion37can be parallel one another. In other embodiments, the form factor of locking mechanism35itself can have some radius of curvature corresponding to the expected size of the loop to be formed by the device.

The device inFIGS.22and23therefore provides a continuous curvature, or at least avoids the sharp angled curves of other types of zip ties. In embodiments, the radius of curvature can be between about 1 mm and about 10 mm, such as about ⅛ inch.

FIG.24is a perspective view of a needle that can be used with any of the embodiments described above. In various embodiments, the needle used can have a size and cross-section that matches with the body of the device. For example, a body with a rectilinear cross-section can correspond to a needle having a rectilinear cross-section, while a body with a circular or ovoid cross-section can correspond to a needle having a corresponding circular or ovoid cross-section. As described above, the cross-sectional size of the needle may be the same size or slightly larger than that of the body.

FIGS.25A through29depict a fascia closure device with an alternative recessed style locking mechanism, according to embodiments.