Abstract:
A method for maintaining the alignment of the edges of a wound in the fascia, using a wound closure device, which is a biodegradable compressible structure capable of maintaining the alignment of the edges of the wound during the healing process, an insertion tool for guiding the device into the wound, and a compression tool for compressing the device against the fascia and associated layers. After connecting the insertion tool to the wound closure device, the insertion tool is used to guide the wound closure device through the wound and hold the device in place, The compression tool compresses the wound closure device while the insertion tool holds the device in place. Finally, remove the insertion and compression tools, allowing the wound closure device to remain in place long enough for the wound to heal before the wound closure device degrades.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention generally relates to a wound closure device and a method that is used to repair the defect typically left in the fascia layer during laparoscopic surgery by an instrument called a trocar. 
     Laparoscopic surgery was introduced as an alternative to open surgical methods. Also referred to as minimally invasive surgery, the technique allows for small incision access to the intra-abdominal cavity. The approach utilizes specialized equipment for the purposes of inflating the abdominal cavity with gas, deploying and exchanging instruments during the operation, and real time imaging with a videoscopic camera. 
     A laparoscopic trocar is a surgical device used for laparoscopic procedures to pierce and access the wall of an anatomical cavity, thereby forming a passageway providing communication with the inside of the cavity. Other medical instruments such as videoscopes and operating instruments can thereafter be inserted through the passageway to perform various medical procedures within the anatomical cavity. 
     When the procedures are over, the laparoscopic trocar is removed, leaving a residual defect in the fascia-peritoneal layer. Laparoscopic trocars are typically 5-15 mm in diameter. Generally, any port size larger than 5 mm should be closed because of the risk of hernias. The defect is located deep in the abdominal wall, making it difficult to view. 
     Trocar site herniation is a recognized complication of laparoscopic surgery. Omental and-sometimes-intestinal herniation with incarceration and obstruction has been documented in recent surgical literature, occurring particularly at any trocar insertion site larger than 5 mm that was not sutured at operation. The necessity to perform fascial closure of any trocar insertion site larger than 5 mm has now been established and is routinely practiced worldwide. 
     However, the conventional closure of such a trocar site fascial defect is often technically difficult, frustrating, indefinitely successful, and even sometimes dangerous due to the limited size of skin incision, the depth of the subcutaneous fatty layer, and necessity of blind manipulation. Moreover, the suturing that involves placement of deep blind sutures after the abdomen has been decompressed is a dangerous manipulation that surgeons tend to avoid. 
     A number of techniques and instruments have been suggested to facilitate a safe and secure closure of the fascial defect through the tiny skin opening. Many of these repairs include passing in any way a suture from one side of the trocar wound to the other, and its ligation. For this purpose either a heavy needle or a variety of straight needles through which sutures are passed have been used. Problems arise as both sides of the defect may not be sutured. Also, in overweight and obese patients with thick abdominal walls, reliable fascia closure is very difficult to achieve. This results in a delayed hernia formation such as an incarcerated or symptomic hernia. The literature shows as much as a 6% overall hernia complication rate, resulting in reoperation, rehospitalization, and extended disability. In the best case this results in the need for an elective repair, resulting in rehospitalization. 
     Although as easy and quick methods, these suturing techniques require positioning of the camera and graspers, visualization of the needles during their entrance into the peritoneal cavity, feeding of the graspers or suture passers with the suture loop, all of which are repeated once to thrice for every trocar defect. Any of these suturing techniques are not only time and effort consuming, but also require sophisticated laparoscopic talent and coordination. As more defects at various sites in the abdominal wall are to be closed after advanced laparoscopic operations, the laparoscopic procedures that support the suturing techniques become more complicated and complex. The above-mentioned suturing techniques would therefore be not that easy and quick. 
     Techniques using such instruments as the Carter-Thomason or Riza-Ribe® needles work by adding a catch onto the end of a needle assembly to catch a free floating suture. To facilitate the closure of the fascia defects of a trocar entry site greater than 5 mm, the surgeon places the upper end of a dissecting forceps through the fascial defect and tilts it so that the peritoneum comes into contact with its flat surface. An assistant retracts the skin and subcutaneous tissue and the needle with the appropriate suture material is then used to take a stitch through the fascia under direct vision. The sharp end of the needle is prevented from coming into contact with any deeper structure as it slides on the flat surface of the dissecting forceps. The stitch is then pulled up to lift the edge of the fascia and the needle is passed from the opposite edge of the fascia in the same manner and then the suture is ligated. 
     Moreover, a series of manipulations is needed to complete a single suturing. The conventional suturing technique involves much traumatic manipulation including pushing, pulling and retraction of the wound, and insertion and extraction of needles. Most of the time the needle is passed twice, and sometimes more. As manipulation in the wound increases, the inflammation and risk of ensuing infection rise considerably. The edema and the collection of seroma and hematoma at the wound further cause dehiscence and hernia formation on a long-term basis. 
     Excessive traumatic manipulation and suturing with heavy sutures oppose the “minimal damage” basis of laparoscopic surgery. The patients are subject to pain and complications at their trocar sites in the postoperative period. The problems associated with the repair of trocar wound would be annoying to the patient as he (or she) is discharged on the first or second postoperative day. The problems of the wound would cause the patient to refer back to the institution. 
     Any of these suturing techniques are to be done under direct vision. It is however impossible to repair the last trocar wound under direct vision. Unless a 0.5 cm scope is used, the last large trocar site can only be closed with conventional blind sutures. At a regular laparoscopic cholecystectomy, the surgeon can only repair the first of two large trocar defects under direct vision. He must close the last one blindly. 
     No matter which suturing technique or needle is used, it is not possible to eliminate the trocar site hernias completely. As described in Malazgirt (US Patent Application, pub #20060015142 published Jan. 19, 2006), the current incidence is reportedly around 0.77-3%. As complex Laparoscopic surgery becomes more common, the incidence of this complication increases. The reported rates of hernia show that there is not yet any superior method in the safe closure of the trocar fascial defect. 
     Eldridge and Titone (U.S. Pat. No. 6,120,539 Issued Sep. 19, 2000) proposed a prosthetic repair fabric constructed from a combination of non-absorbable tissue-infiltratable fabric which faces the anterior surface of the fascia and an adhesion-resistant barrier which faces outward from the fascia. This prosthetic requires the use of sutures to hold it in place. 
     Eberbach (U.S. Pat. No. 5,366,460 Issued Nov. 22, 1994) proposed the use of a non-biodegradable fabric-coated loop inserted through the defect into the fascia wall, pressing against the posterior fascia wall from the intra-abdominal pressure. 
     Agarwal et al (U.S. Pat. No. 6,241,768 Issued Jun. 5, 2001) proposed a prosthetic device made of a biocompatible non-biodegradable mesh, which sits across the fascia defect using the abdominal pressure to hold it in place. 
     Rousseau (US Patent Publication #20030181988) proposed a plug made of biocompatible non-biodegradable material which covers the anterior side of the fascia, the defect, as well as the posterior side of the fascia. 
     Malazgirt (US Patent Publication #20060015142) proposed a plug/mesh non-biodegradable combination for repair of large trocar wounds. It is stated that it requires at least a “clean flat area around with a radius of 2.5 cm”, and requires staples to hold it in place. 
     Ford and Torres (US Patent Publication #20060282105) proposed a patch with a tether or strap, all made of non-biodegradable biocompatible material placed against the anterior wall of the fascia defect. 
     SUMMARY 
     A device and methods for closing a wound in the fascia and associated layers are disclosed. The device includes a biodegradable implantable device, an insertion tool and a compression tool. The biodegradable implantable device includes a biodegradable compressible structure of such size and shape that it is capable of maintaining the alignment of the edges of the wound. One or more embodiments of the biodegradable compressible structure include a structure with a surface to make contact with the inner surface of a wound, another structure with a surface to contact with the outer surface of a wound, a means for connecting the two bases such as a screw or snap fitting, and a means for detachably connecting the compressible structure to an insertion tool such as grooves or a slotted ring. The insertion tool provides a means for inserting the biodegradable compressible structure into the wound and a means for exerting a force on the biodegradable compressible structure such that the two biodegradable bases move closer to each other and compress the fascia and associated layers of the abdominal wall. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a transparent view of the device at the end of the compression process in accordance with one or more embodiments of the present invention. 
         FIG. 2  shows a transparent view of the device for closing a wound in accordance with one embodiment of the present invention. 
         FIG. 3  shows a view of the disassembled parts in accordance with one or more embodiments of the present invention. 
         FIG. 4  shows a cross-section of an embodiment of the wound closure device. 
         FIG. 5  shows a detailed bottom view of the subfascial button in accordance with one or more embodiments of the present invention. 
         FIG. 6  shows a detailed top view of the superfascial button along with its attached screw in accordance with one or more embodiments of the present invention. 
         FIG. 7  shows a view of the top of the superfascial button in accordance with one or more embodiments of the invention. 
         FIG. 8  shows a view of the bottom of the superfascial button and screw assembly for one or more embodiments of the current invention. 
         FIG. 9  shows a detailed view of the central insertion stem in accordance with one or more embodiments of the present invention. 
         FIG. 10  shows a detailed view of the hollow tube component in accordance with one or more embodiments of the present invention. 
         FIG. 11  shows a view of the device in accordance with one or more embodiments of the current invention. 
         FIG. 12  shows a view of an embodiment of the wound closure device when it is being compressed into the wound. 
         FIG. 13  shows a view of an embodiment of the device being inserted through the tunnel. 
         FIG. 14  shows a view of an embodiment of the device in place. 
         FIG. 15  shows a view of an embodiment of the device during the healing process. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows a transparent view of an embodiment of the insertion tool, compression tool, and the wound closure device. The wound closure device consists of a subfascial button  102 , screw  110 , and superfascial button  104 . In one or more embodiments, the insertion tool consists of a central insertion stem  108 . In one or more embodiments, the compression tool consists of an outer tube  106 . 
     In one or more embodiments, the superfascial button  104  is permanently attached to the screw  110 . The screw  110  gets inserted into a threaded hole in the subfascial button  102 . These three components make up what is referred to as the “wound closure device”. The central insertion stem  108  screws into a threaded hole in the base of the subfascial button  102 . The central insertion stem  108  is used by someone on the surgical team to guide the wound closure device into the wound. The hollow tube  106  slips over the central insertion stem  108  onto a connector on top of the superfascial button  104 . The hollow tube  106  can then be used to tighten the wound closure device onto the fascia around the wound. In one or more embodiments, the central insertion stem  108  is longer than the hollow tube  106 , sufficiently longer so that both the hollow tube  106  and central insertion stem  108  can be held by one person at the same time. Once the wound closure device is tightened, the central insertion stem  108  and hollow tube  106  can be removed. 
       FIG. 2  shows a direct side-on hidden line view of an embodiment of the wound closure device, compression tool, and insertion tool. The subfascial button  102  is shown in position after compression against the superfascial button  104 , with the hollow tube  108  and central insertion stem  108  still attached. The screw  110 , part of the superfascial button  104  is shown screwed into the subfascial button  102 . 
       FIG. 3  shows a view of each of the parts disassembled. The subfascial button  102  will be attached to the superfascial button  104  via the screw  110 . In one or more embodiments the screw is part of the superfascial button  104 . The screw  110  and superfascial button  104  have a central hole large enough for the central insertion stem  108  to slide through so that it can be attached to the base of the subfascial button  102 . Connecting the central insertion stem  108  to the base of the subfascial button  102  provides stability to the device during insertion. In one or more embodiments, the threads holding the central insertion stem  108  to the base of the subfascial button  102  are of an opposite handedness to the threads holding the screw  110  to the base of the subfascial button  102 . This means that tightening one will not loosen the other, which would be a serious issue as one would not want to loosen the screw  110  when detaching the central insertion stem  108 . 
       FIG. 4  shows a cross-sectional view of the assembly. The face  420  of the subfascial button  102  has one or more protrusions  414  attached. The face  420  of the subfascial button is of a smaller diameter than the cupped  402  portion of the superfascial button  104 , such that the protrusions  414  of the subfascial button  102  fit inside the cupped portion  402  of the superfascial button  104 . The central insertion stem  108  fits into threads in the subfascial button  412  which extend from the threads in the subfascial button for the screw  410 . There is also a gap between the edge of the subfascial button face  420  and the inner wall of the cupped portion  402  of the superfascial button, the gap allowing the fascia and associated layers to be engaged by the device, keeping the device in the location of the wound. 
     Subfascial Button 
       FIG. 5  shows a view of the subfascial button as it is in one or more embodiments. The subfascial button  102  consists of a cone  508  and a base  506 . The base  506  is of roughly constant diameter. In one or more embodiments, the cone  508  allows the wound closure device to push through the wound easier. The subfascial button has a hole with screw threads  502  substantially through the center of the face  504  extending through the base  506  and into the cone portion  508 , such that the screw threads  502  are deep enough to stably connect the subfascial button  102  to the screw. The diameter of the subfascial button  102  at the end of the screw threads is such that neither reasonably sufficient torque on the screw used to tighten the screw into the subfascial button  102  nor the act of pushing the subfascial button cone  508  through the fascia would cause the subfascial button  102  to crack. Not shown in the figure but clearly shown in other figures is a smaller hole deeper into the cone  412 . This hole is also substantially through the center, has threads of a handedness and a diameter that it can connect with the central insertion stem  108 . 
     In one or more embodiments, the subfascial button base  506  has a thin, flat profile of a few millimeters in thickness, is moderately rigid in structure and circular or elliptical in shape. This profile is desirable to lessen the likelihood of the patient&#39;s awareness of its presence or discomfort during the post-operative healing interval. 
     In one or more embodiments, a counter-rotational or frictional control feature can be added to the subfascial button face  504  such as small protrusions  414  of a conical shape to prevent the tendency to rotate during the process of tightening the superfascial button  104  onto the anterior surface of the fascia. In one or more embodiments, this frictional control feature is implemented where the face of the subfascial button  504  is textured with a patterned surface to offer frictional control such that, in use, the textured side is placed in direct contact with the fascia and associated layers of the abdominal wall, and covers the wound. Its purpose is to align the edges of the defect (i.e. anatomical alignment), and hold them in place to facilitate the healing process. In one or more embodiments, the texture is a non-smooth (unpolished) frictional control surface feature to assure that the subfascial button  102  remains in position and does not slide or shift laterally during the healing interval. 
     As deployed and implanted, the subfascial button  102  is located under the fascial defect and is a mating member of the wound closure device. Like the superfascial button  104 , the goals of the subfascial button is to close and securely align the trocar port defect in the fascia and associated layers, and hold it in place for the intended healing interval. And, similarly, its purpose is fulfilled and completed at the end of the intended healing interval when the wound closure device should dissolve. 
     The Screw 
     The screw  110  is of such length so that it can be inserted into the subfascial button  102  and still has sufficient length to straddle the fascia. In one or more embodiments, it must also be of large enough diameter to enable the central insertion stem  108  to be inserted through the screw into the finer threads of the subfascial button. In one or more embodiments, the length of the screw  110  can be made at varying lengths to enable use for patients with differing tissue thicknesses and minimize the exposure of the screw  110 . In one or more embodiments, the screw  110  is permanently attached to the bottom of the superfascial button  104 . In other embodiments, the screw  110  is independent of the subfascial button and superfascial button  104 , and so the length of the screw  110  must be taken into account to minimize the length of the screw  110  present beyond the superfascial button  104 . 
     In one or more embodiments, the diameter of the screw  110  may be made at varying widths to support the closure of different diameter wounds. In one or more embodiment, the screw  110  has a hole through its center which accepts the central insertion stem  108 . In one or more embodiments, where the screw  110  is not permanently attached to the superfascial button  104 , to prevent loosening, the threads between the screw  110 , superfascial button  104  and subfascial button  102  are a different hand-sense (i.e. right-handed vs. left-handed) than the threads between the subfascial button  102  and central insertion stem  108 . 
     In one or more embodiments, the screw  110  can be permanently connected to or an integral part of the subfascial button  102 . 
     In one or more embodiments, the screw  110  may be replaced by a locking or clasping mechanism. This locking or clasping mechanism can be configured with frictional features or racheting and interlocking protrusions to secure the subfascial button base  420  and superfascial button base  418  components together, and hold them with the desired degree of tension across the fascia and associated layers. 
     Superfascial Button 
     As shown in  FIG. 6 , the superfascial button  104  consists of a base  606  and a connector  602 , the base  606  being closer to the fascia and associated layers. The superfascial button  104  has a hole through the center  604  which allows the central insertion stem  108  to be slipped through it unobstructed. In one or more embodiments, the connector  602  consists of one or more grooves or slots that are deep enough so that a compression tool with protrusions could be inserted into the grooves. The compression tool would have enough contact between the protrusions and the grooves such that torque can be applied by the tool to tighten the superfascial button  104  onto the subfascial button  102 . 
     As shown in  FIG. 7 , in one or more embodiments, the connector may be embodied as a raised ring  704  with two or more notches  706  in the ring. These notches  1006  are in a pattern that matches the pattern of protrusions attached to the end of an embodiment of a compression tool. The notches  706  are of enough width to accommodate the protrusions. As with other embodiments, this embodiment would also have a screw attached  702  and a central hole  708  to allow the central insertion stem  108  to slip through it. 
     An embodiment of the superfascial button  104  is shown in  FIG. 8 . In one or more embodiments, the superfascial button base  804  has a thin, flat profile of a few millimeters in thickness, is moderately rigid in structure and circular or elliptical in shape. This profile is desirable to lessen the likelihood of the patient&#39;s awareness of its presence or discomfort during the post-operative healing interval. In one or more embodiments, the base would have sides which curve upward at the edges  802 . The sides should be high enough above the flat profile so that fascia and associated layers are engaged between the inner wall of the side and the edge of the subfascial button. By doing so, the sides encourage the device to remain at the location of wound, further assuring the anatomical alignment of the wound edges, and countering the tendency of the fascia and associated layers to pull away. 
     In one or more embodiments, the screw  110  is permanently attached to the base  806 . There is a hole in the screw  808  that is aligned with the hole through the superfascial button  604 . The hole is of such size and shape to allow the central insertion stem  108  to slip through it unobstructed. 
     In one or more embodiments, the superfascial button base  606  has a thin, flat profile of a few millimeters in thickness, is moderately rigid in structure and circular or elliptical in shape. This profile is desirable to lessen the likelihood of the patient&#39;s awareness of its presence or discomfort during the post-operative healing interval. 
     General Composition of the Wound Closure Device 
     Materials specified for the wound closure device are specific for its intended application and use. The scope of materials that will satisfy the requirements of this application is unusually narrow. This is a direct consequence of the specificity and functional demands characteristic of the intended surgical application. 
     The intention for the wound closure device is to close and secure the trocar port defect in the fascia. This requires a known and finite healing interval of some three to five months. Its purpose fulfilled at the end of this period, making continued presence of the closure device a potential liability. To prevent it from becoming a source for irritation once the healing process is completed, the implanted closure device should be removed. Consequently, to avoid the need for a second surgical intervention to remove the device, Maurus and Kaeding (Maurus, P. B. and Kaeding, C. C., “Bioabsorbable Implant Material Review”,  Oper. Tech. Sports Med  12, 158-160, 2004) found it was a primary requirement for the wound closure device is that it is biodegradable. This means that the materials will degrade or disintegrate, being absorbed in the surrounding tissue in the environment of the human body, after a definite, predictable and desired period of time. One advantage of such materials over non-degradable or essentially stable materials is that after the interval for which they are applied (i.e. healing time) has elapsed, they are no longer a contributing asset and do not need subsequent surgical intervention for removal, as would be required for materials more stable and permanent. This is most significant as it minimizes risks associated with repeat surgeries and the additional trauma associated with these procedures. 
     A disadvantage of these types of materials is that their biodegradable characteristic makes them susceptible to degradation under normal ambient conditions. There is usually sufficient moisture or humidity in the atmosphere to initiate their degradation even upon relatively brief exposure. This means that precautions must be taken throughout their processing and fabrication into useful forms, and in their storage and handling, to avoid moisture absorption. This is not a serious limitation as many materials require handling in controlled atmosphere chambers and sealed packaging; but it is essential that such precautions are observed. Middleton and Tipton (Middleton, J. and Tipton A. “Synthetic Biodegradable Polymers As Medical Devices”  Medical Plastics and Biomaterials Magazine , March 1998) found that this characteristic also dictates that their sterilization before surgical use cannot be done using autoclaves, but alternative approaches must be employed (e.g. exposure to atmospheres of ethylene oxide or gamma radiation with cobalt 60). 
     While biodegradability is an essential material characteristic for the wound closure device, the intended application is such that a further requirement is that the material is formulated and manufactured with sufficient compositional and process control to provide a precisely predictable and reliable degree of biodegradability. This means a typical biodegradation interval of three to five months, corresponding to the healing interval for the trocar defect in the fascia layer. 
     In these materials, simple chemical hydrolysis of the hydrolytically unstable backbone of the polymer is the prevailing mechanism for its degradation. As discussed in Middleton and Tipton (Middleton, J. and Tipton A referenced previously), this type of degradation when the rate at which water penetrates the material exceeds that at which the polymer is converted into water-soluble materials is known as bulk erosion. 
     Biodegradable polymers may be either natural or synthetic. In general, synthetic polymers offer more advantages than natural materials in that their compositions can be more readily finely-tuned to provide a wider range of properties and better lot-to-lot uniformity and, accordingly, offer more general reliability and predictability and are the preferred source. 
     Synthetic absorbable materials have been fabricated primarily from three polymers: polyglycolic acid (PGA), polylactic acid (PLA) and polydioxanone (PDS). These are alpha polyesters or poly(alpha-hydroxy) acids. The dominant ones are PLA and PGA and have been studied for several decades. One of the key advantages of these polymers is that they facilitate the growth of blood vessels and cells in the polymer matrix as it degrades, so that the polymer is slowly replaced by living tissue as the polymer degrades (“Plastic That Comes Alive: Biodegradable plastic scaffolds support living cells in three dimensional matrices so they can grow together into tissues and even whole organs” by  Cat Faber Strange Horizons  http://www.strangehorizons.com/2001/20010305/plastic.shtml) 
     In recent years, researchers have found it desirable for obtaining specific desirable properties to prepare blends of these two dominant types, resulting in a highly useful form, or co-polymer, designated as PLGA or poly(lactic-co-glycolic acid). 
     In one or more embodiments, the biodegradable wound closure device may be made of biodegradable material of different stability (i.e. half-life). While it is important for the material that is in direct contact with the fascia or lending support to that (the subfascial button base  506 , screw  110 , and superfascial button base  606 ) needs to stay in place for a few months, while the rest of the implantable structure can degrade significantly in a matter of weeks without affecting the performance of the payload. In one or more embodiments, the screw  110  would degrade sooner than the subfascial button base  506  and superfascial button base  606 , so that the ends of the defect are allowed to grow together while protecting the surface of the defect. 
     Material for the Subfascial Button 
     Owing to its necessarily and virtually inaccessible location beneath the fascia and peritoneum and its need to be placed and positioned correctly and precisely in proper alignment with the superfascial button base  606  located on the other side, the material used for the subfascial button base  506  must be even more specialized than the superfascial button base  606 . That is, besides the same requirement for biodegradability and biocompatibility, the additional need for its placement and positioning in a virtually inaccessible and invisible location imposes much more stringent specifications and limitations upon the grade of polymer used for this component. 
     In one or more embodiments, the subfascial button  102  is made from shape memory biodegradable polymer, such that the cross-section of its insertion is small, but over time it expands against the fascia. In one embodiment, it would be inserted in a teardrop shape, and once in place expand into a flattened disc-like shape. 
     Although various pre-insertion bending and folding manipulative procedures might be conceived and envisioned for controlling the profile of the subfascial button base  506  to enable it to be inserted into and through the subcutaneous tissue and fascial defect and then, somehow, unfolded and flattened, and deployed into its desired position correctly aligned with the superfascial button  104 ; such requirements are considered essentially unreliable, excessively time-consuming and of seriously doubtful feasibility for a practical and increasingly common surgical procedure. For these reasons, in one or more embodiments of the invention, the material contemplated for the subfascial button base  506  is a co-polymer having the desired biodegradability characteristics for the application, but also one that possesses a shape-memory property. Shape memory polymers are discussed in Lendlein and Kelch (Lendlein, A. and Kelch, J. “Shape-Memory Polymers”  Angewandte Chem. Int. Ed.,  41, 2034-2057 (2002)) and described further in Kawai and Matsuda (U.S. Pat. No. 4,950,258, issued Aug. 21, 1990). 
     Polymer systems with shape-memory properties have an attractive and broad application potential in minimally invasive (e.g. laparoscopic) surgery, the field of interest for this invention. Absorbable implants of the material can be inserted into the human body in a compressed or deformed (temporary) shape through a small incision (as the trocar fascial defect of this disclosure). After being placed into the desired position, (Kawai and Matsuda (U.S. Pat. No. 4,950,258, issued Aug. 21, 1990) described how shape memory polymers can be reverted back to their desired final functional shape upon warming to body temperature. 
     During the appropriate healing interval, the implant is degraded and absorbed, making subsequent surgery to remove the implant unnecessary. These shape-memory materials may be suitably modified to achieve the precisely desired behavior for specific applications. 
     For biomedical applications such as the wound closure device, a thermal transition of the shape of the shape-memory material in a fairly narrow temperature range between room (ambient) and body temperature is desired. Such materials have been developed and are available for application in the present contemplated invention. Nevertheless, because of the demanding nature of this application and the need for rigidly narrow operating temperature limits, as well as assurance of adequate mechanical properties, it is expected and probably unavoidably necessary that some co-polymer development will be required to achieve an optimal balance of properties for this very specific application. 
     In use, and having an implantable subfascial button  102  of the desired geometry of optimal material, the circular or elliptically shaped disc would be deformed such that its deformed profile would be readily insertable into and through the subcutaneous tissue layer and trocar fascial defect. This maneuver would desirably take place within a brief time interval to assure that the polymeric material did not reach its shape-memory transition temperature (i.e. body temperature) before being positioned into its required and desired location behind or under the fascial defect. 
     Material for the Superfascial Button 
     Depending upon the ratio of lactide-to-glycolide used for polymerization, different forms or grades of PLGA are obtainable. These are usually identified according to the monomers&#39; ratio and are so designated in the literature and suppliers&#39; brochures. PLGA has been successful as a biodegradable polymer for medical applications because it undergoes hydrolysis in the body to produce the original monomers, lactic acid and glycolic acid. 
     The two monomers associated with PLGA, lactide and glycolide, under normal physiological conditions, are byproducts of various metabolic pathways in the human body. Since the body effectively deals with these two monomers, there is minimal system toxicity associated with use of this co-polymer. A notable feature of PLGA is that it is possible to tailor the polymer degradation interval by adjusting the ratio of monomers. In light of the versatility of the PLGA co-polymer and its record of successful use in a wide range of bio-absorbable applications, it is the specified material for the superfascial button base  606 . 
     Insertion Tool 
     In one or more embodiments, the insertion and the minimal positioning expected to be required would be accommodated with an attached positioning stem fastened to the subfascial button  102 . The insertion tool consists of an insertion mechanism to place the wound closure device into position at the fascia defect. In one or more embodiments, the insertion mechanism is a central insertion stem  108  as described below. 
     Central Insertion Stem 
     The central insertion stem enables the wound closure device to be inserted through the trocar tunnel (subcutaneous tissue layer) and fascial defect and placed below the fascia. As shown in  FIG. 9 , the central insertion stem  108  is a solid piece of cylindrical material which is threaded at the lower end. These threads  904  are of sufficient length to attach to the biodegradable wound closure device into the screw to hold the biodegradable wound closure device steady throughout an insertion procedure. The stem handle  902  must be of significant length to be grasped while allowing one to simultaneously grasping the outer tube body. In one or more embodiments, the diameter of the central insertion stem  108  used in a particular procedure may vary to support different wound sizes. 
     The central insertion stem  108  would extend up and out in a forward anterior direction through the fascia defect and be manually manipulateable by the surgeon. At this point, with the subfascial button in its proper position under the fascia defect, it can be brought up against the peritoneum and underside of the fascia by the surgeon simply exerting an upward (outward) manual force upon the central insertion stem. 
     In one or more embodiments, a frictional or racheting holding feature is provided between a hole in the superfascial button and the lower surface of the central insertion stem whereby the superfascial button becomes secured to the central insertion stem, allowing the subfascial button base  506  and superfascial button base  606  to sandwich the fascia and associated layers between them. This feature is designed to allow the desired degree of compressive force to be maintained without further application of continual external manual pressure. At this point in the closure device implant procedure the closure device is self-sustaining, independent of the need for external force and in its desired position. 
     Outer Tube 
     As shown in  FIG. 10 , the outer tube  106  is a hollow tube that fits over the central insertion stem  108  at one end and into the connector of the superfascial button  602  at the other. The outer tube  106  has a body  1010  that is of significant length to enable one to grasp it comfortably from outside the body, and one or more protrusions  1006  which enable the outer tube  106  to detachably connect to the connector  602 . The inner diameter of the outer tube  106  should be significantly greater than the diameter of the central insertion stem  108  to enable to the outer tube  106  to slide over the central insertion stem  108  unobstructed. In one or more embodiments, the outer diameter of the outer tube  106  must be smaller than the diameter of the superfascial button  104  to allow the outer tube  106  to sit on top of the superfascial button  104 . In other embodiments, the outer tube  106  may be wider than the superfascial button  104  such that the protrusions  1006  on the bottom of the outer tube can be inserted into the grooves  602  on the superfascial button  104 . 
     In one or more embodiments, as shown in  FIG. 10 , the face of the outer tube  1004  is surrounded by a curved edge  1002  in such a way so that it substantially covers the head of the superfascial button, improving the stability of the connection between the outer tube and superfascial button. 
     Once the wound closure device has been put into place by the central insertion stem  108 , the outer tube  106  would be introduced to allow the surgeon to assure mutual seating of both the subfascial button  102  and superfascial button  104  tightly against either side of the fascia. This would simply require application of an upward manual force to the central insertion stem (attached to the subfascial button) and simultaneously-applied downward pressure to the hollow tube  106  contacting the superfascial button  104 . Such opposing manual forces would readily bring the superfascial button  104  and subfascial button  102  together with the fascia sandwiched in between. In one or more embodiments, this downward force on the hollow tube  106  would also require a torque force to turn the superfascial button  104  so that it moves closer to the subfascial button. 
     The wound closure device only comes into play toward the end of the surgical event, after the surgical procedure has essentially been completed. At this stage, the intent is to close the trocar port to prevent any subsequent risk of herniation at the defect sites, a risk with present suturing closure methods. Accordingly, since the trocar will have already been removed along with the videoscope, and the abdominal cavity deflated, visibility and maneuverability within the abdominal cavity are necessarily severely restricted. This is in contrast to the significantly more accessible and visible situation at this location during the surgical procedure itself. 
     Material of the Central Insertion Stem 
     In one or more embodiments, the central insertion stem  108  is made of material that is non-reactive but not itself biodegradable. The central insertion stem  108  can be discarded or reused, and may be made in varying lengths to enable surgeons in different situations dealing with patients of different sizes to be able to control the placement of the biodegradable wound closure device. 
     In one or more embodiments, the central insertion stem  108  is fabricated of two polymers of differing grades—a short-term degradation material at the protruding end, and a longer-term material at the location of the holding mechanism. Such a dual-material component might be readily assembled using a mechanical or other joint type at the desired location along its length, where the two polymer grades intersect. Upon completion of the surgical procedure and implanting of the wound closure device, the protruding central insertion stem  108  can be cut off below the anterior surface of the subcutaneous layer but above the juncture of the two grades of polymer. With a short-term biodegradable material for the anterior portion of the central insertion stem  108 —well beyond the superfascial button  104  and its securing frictional or racheting feature—the potential problem with stem removal is eliminated. To avoid a possible mix-up during fabrication and assembly of such a dual-material central insertion stem the different grades of polymer could be tinted different colors. 
     Description of Use of One or More Embodiments of the Invention 
     One or more embodiments of the use of this invention are described herein. 
     Connect the subfascial button  102  to the assembly consisting of the screw  110  and superfascial button  104 . In one or more embodiments, the superfascial button  104  could be a separate component which needs to be connected to the screw  110 . The central insertion stem  108  can then be connected to the biodegradable wound closure device by threading it onto the screw  110 . In one or more embodiments, the superfascial button  104  can be inserted over the central insertion stem  108  prior to attempting to implant the wound closure device. In other embodiments, the superfascial button  104  can be inserted after the subfascial button  102  is implanted. In other embodiments, the superfascial button  104  is permanently attached to the screw  110 , such that the superfascial button-screw assembly is threaded into the subfascial button  102 , and the central insertion stem  108  is threaded into a threaded hole in the subfascial button  412 . 
     Using the central insertion stem  108 , guide the biodegradable wound closure device to the wound site and press it through the site. Then pull back on the central insertion stem  108  to cinch it in place. In one or more embodiments, if not already done place the superfascial button  104  on the central insertion stem  108 , connector-side up and allow it to slide into position at the top of the subfascial button  104 . 
     Once the biodegradable wound closure device is in place, place the outer tube  106  over the central insertion stem  108  by sliding the outer tube over the central insertion stem  108  through the hole in the outer tube  408  and slide the outer tube  106  into place over the superfascial button connector  602 .  FIG. 11  shows what the configuration would look like in one or more embodiments of the present invention. 
     Rotate the outer tube  106  until the outer tube protrusions  1006  line up with the superfascial button connector  602 . The outer tube  106  should drop slightly so that the protrusions  1006  are inside the superfascial button connector  602 . 
     Once the outer tube  106  is in place, it can be used to compress the biodegradable wound device against the fascia and associated abdominal layers. While grasping the central insertion stem  108  with one hand. Rotate the outer tube  106  in the direction appropriate to the threads of the screw  110 , until it feels tight. In one or more embodiments, this direction would be the opposite sense of the threads on the central insertion stem  904  to prevent it from slipping out.  FIG. 12  shows the resulting configuration where the biodegradable wound device has been compressed. 
       FIG. 13  shows an embodiment of the invention in place. As stated previously, the laparoscopic trocar is removed, leaving a residual defect in the fascia-peritoneal layer  1306  under the skin  1302  which goes through the skin  1302  and intermediate tissue layers above the fascia  1306  and into the wound  1308 , after the laproscopy tunnel and surgical tools have been removed. The ability for the surgeon to see into the wound is impaired because there is nothing holding the sides of the wound up. The surgeon would hold the central insertion stem  108  to keep the subfascial button  102  in place while applying a rotational force to the outer tube  106  over the screw  110  to move the superfascial button  104  toward the subfascial button  102 . This results in compressing the fascia between  1304  it. 
       FIG. 14  shows an embodiment of the invention after the central insertion stem  108  and outer tube  106  have been removed. The fascia  1304  is compressed and pushed into the area under the superfascial button  104  by the protrusions  414  on the subfascial button  102 . The combination of the compression and pushing mechanism acts to keep the device in place after the insertion process is complete. 
       FIG. 15  shows an embodiment of the invention during the healing process. The skin  1302  and fascia-peritoneal layer  1306  have healed over the area of the tunnel and the wound  1308  is healing. The material of the screw  110 , subfascial button  102 , and superfascial button  104  are still on the wound  1308  because of the initial compression and pushing of the tissue, but are degrading. By the time they degrade to the point where they no longer provide any engagement with the fascia tissue  1304 , the wound  1308  will have healed sufficiently to complete the process. 
     Once the biodegradable wound closure device has been compressed against the fascia as shown in  FIG. 13 , the outer tube  106  can be removed.  FIG. 14  shows an embodiment of the wound closure device against the fascia wound  1308  with the central insertion stem  108  removed. The wound closure device is left in place by unscrewing the central insertion stem  108  from the subfascial button threads  412 . The wound can be closed at the epidermal layers. As shown in  FIG. 15 , the fascia wound  1308  will heal and the biodegradable wound closure device will dissolve over time. In one or more embodiments, the biodegradable wound closure device will be constructed of biodegradable polymers of various expected degrading times, such that the parts of the wound closure device which are not required to hold the wound in place will dissolve faster than the parts that are required to hold the wound in place.