Abstract:
A substantially U-shaped staple has a bridge, legs, and an internally disposed compression device with a bias portion having a compression surface movably disposed between the legs and a compression resistor connected to the bridge and to the compression surface and is formed to resist movement of the compression surface towards the bridge with a force.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application: 
     is a divisional of U.S. patent application Ser. No. 13/222,758, filed on Aug. 31, 2011, now U.S. Pat. No. 8,679,156, issued on Mar. 25, 2014, which: 
     
         
         
           
             is a divisional of U.S. patent application Ser. No. 11/971,998, filed on Jan. 10, 2008, now U.S. Pat. No. 8,679,154, issued on Mar. 25, 2014, which:
           claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 60/880,146, filed on Jan. 12, 2007; and
 
is a divisional of U.S. patent application Ser. No. 11/971,998, filed on Jan. 10, 2008, now U.S. Pat. No. 8,679,154, issued on Mar. 25, 2014, which:
   
         
             claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 60/880,146, filed on Jan. 12, 2007,
 
the complete disclosures of which are hereby incorporated by reference herein in their entireties.
 
           
         
       
    
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     n/a 
     FIELD OF THE INVENTION 
     The present invention lies in the field of staple fastening, in particular, staples and instruments capable of applying a single or a plurality of staples to a material and processes therefor. More particularly, the present invention relates to a staple capable of placing a load-bearing force against the material being stapled and improvements in processes for stapling material. The device can be used, particularly, in the medical field for stapling tissue during surgical procedures, whether open, endoscopic, or laparoscopic. 
     BACKGROUND OF THE INVENTION 
     Conventional staples are, typically, U-shaped and require a staple cartridge and anvil to fasten the staple onto a material. The U-shape of the staple can be considered relatively square-cornered because of the sharp angle at which the legs extend from the bridge. On activation of a stapling device, the staple legs are advanced forward so that they penetrate a material on both sides of a slit or opening. As a staple former is advanced further, the legs of the staple bend around the anvil causing the tips of the legs to advance along an arcuate path toward each other so that the staple ultimately assumes a generally rectangular shape, thereby compressing the material that has been trapped between the staple legs, which is tissue in surgical applications. This compression of the material is the mechanism by which a closure is effected. Depending on the length of the incision or opening, a series of staples will be delivered along its length, which can ensure a blood tight closure in surgical procedures. 
     Because the staple has two legs that pierce the material, they are well suited for fastening two or more layers of material together when used with the opposing anvil. Whether used in an office or during a surgical procedure, most staples  1  have similar shapes—a bridge  2  connecting two relatively parallel legs  4 , which legs are disposed approximately orthogonal to the bridge  2 , which, depending on the material of the staple, results in a square-cornered U-shape. In surgical stapling devices, it is beneficial to start the legs  4  in a slight outward orientation to assist retention of the staples within the cartridge. The staple illustrated in  FIG. 1  is representative of conventional surgical staples. Such staples are compressed against an anvil to bend the tips of the legs  4  inward. For purposes sufficient in surgery, the final stapled configuration has a stapling range from a “least” acceptable orientation to a “greatest” acceptable orientation. The “least” acceptable staple range is a position where the tangent defined by the tip of each leg  4  is at a negative angle to a line parallel to the bridge  2  and touching the lower portions of both legs  4 . The “greatest” acceptable staple range is a position where the legs  4  are bent into a shape similar to the letter “B.” 
     The staple  1  of  FIG. 1  is shown in an orientation where the tips of the legs  4  are bent slightly by an anvil on the way towards a final stapled form. (This slightly bent orientation is also present with respect to the staples illustrated hereafter.) The legs  4  of such slightly bent staples have three different portions:
         a connecting portion  6  (at which the legs  4  are connected to the bridge  2 );   an intermediate portion  8  (at which the staple is bent; of course it is also possible for the connection portion  6  to be bent for various fastening purposes); and   a piercing portion  10  (for projecting through the material to be fastened; this portion, too, is bent when fastening).
 
Many stapling devices exist to deploy such staples. Some surgical stapling instruments are described in U.S. Pat. No. 5,465,895 to Knodel et al., and U.S. Pat. Nos. 6,644,532 and 6,250,532 to Green et al. When the staple  1  is bent for fastening, the polygon formed by the interior sides of the bent staple  1  defines an envelope or a central region  14 . The material to be fastened by the staple  1  resides in and is compressed within the central region  14  when stapling occurs. When the final staple orientation is B-shaped, there can be two regions in which the tissue is held and compressed.
       

     One common feature associated with conventional staples is that there is no controllable way of adjusting the compressive force that is applied by the staple to the material being stapled. While items such as paper and cardboard can withstand a wide range of stapler compressive force without breaking or puncturing, living tissue, such as the tissue to be fastened in a surgical procedure, has a limited range of compressive force and cannot withstand force greater than a upper limit within that range without causing tissue damage. In fact, the range of optimal stapling force for a given surgical stapling procedure is relatively small and varies substantially with the type of tissue being stapled. 
     While it may be true that the distance between the bending point of the legs and the bridge (see, e.g., span  12  in  FIG. 1 ) can be increased to impart less force on material within the staple, this characteristic does not apply when living tissue having varying degrees of hardness, composition, and flexibility is the material being stapled. Even if the staple leg bending distance  12  is increased, if more or less or harder or softer tissue than expected is actually captured within the staple, the force applied to the captured tissue will not be controlled and will not be optimal for that tissue. 
     When one, two, or more layers of tissue are being stapled, it is desirable for the tissue to be at a desired compressive state so that a desirous medical change can occur, but not to be at an undesired compressive state sufficient to cause tissue necrosis. Because there is no way to precisely control the tissue that is being placed within the staple, it is not possible to ensure that the tissue is stapled within an optimal tissue compression range, referred to as an OTC range. Therefore, ruling out of tissue necrosis is difficult or not possible. Further, tissue presented within one staple may not be the same tissue that is presented within an adjacent staple or is within another staple that is fired during the same stapling procedure. Thus, while one or a few of a set of staples could actually fasten within the OTC range, it is quite possible for many other staples in the same stapling procedure to fasten outside the OTC range. 
     What is needed, therefore, is an improved staple and improved methods of stapling that allow automatic control of the staple compression force imparted upon the material being stapled so that compression of the material remains within a desired OTC range. While prior art surgical stapling instruments have utility, and may be successfully employed in many medical procedures, it is desirable to enhance their operation with the ability to deliver a staple that can automatically tailor the compression force delivered to the tissue without external mechanics or operations. 
     BRIEF SUMMARY OF THE INVENTION 
     It is accordingly an object of the invention to provide an adjustable compression staple and methods for stapling with adjustable compression that overcome the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that automatically tailors the compression force delivered to the tissue. 
     When tissue is stapled, liquid is forced out of the tissue. The OTC range of the tissue is a compression range in which liquid is removed from the tissue (i.e., desiccates the tissue) without damaging or necrosing the tissue. As the liquid from the tissue exits the tissue due to compression exerted upon the tissue by the staple, however, the compressive force that is being imposed upon the tissue naturally reduces—because less mass is between the opposing staple portions. In some instances, this reduction can allow the imparted tissue compression to exit the OTC range. Staples according to the present invention each have a self-adjusting, pre-tensioned compression device that keeps compression force on the interposed tissue within the OTC compression range even after being desiccated. 
     The prior art staple of  FIG. 1  has a stapling range that is illustrated in  FIG. 17 . For purposes sufficient in surgery, the final stapled configuration of the OTC staples of the present invention has a stapling range that is illustrated, for example, in  FIGS. 18 to 20 . A “least” acceptable staple range is a position where the tangent T defined by the tip of each leg  4  is at a negative angle α to a line L parallel to the bridge  2 . This orientation is illustrated with the left half of the staple in  FIG. 17  merely for reasons of clarity. See also  FIGS. 18 to 20 . A “greatest” acceptable staple range is a position where the legs  4  are bent 180 degrees into a shape similar to the letter “B” (see the exemplary orientation illustrated in the right-half of  FIG. 17 ) but, in comparison to the prior art staple range of  FIG. 17 , as described below in detail, the tips of the legs  4  of the staples according to the invention reach only up to a compressing portion and not further than this compressing portion as shown in  FIG. 20 , for example. In such an orientation, the stapled tips of the legs do not interfere with the OTC device present in the staples according to the invention. 
     The OTC devices for staples according to the invention take many forms. The OTC device can be integral with the legs of the staple and project into a central area or can be attached to the staple to project into the central area. The OTC device can be sinusoidal in shape with a compressing portion at the end of the OTC device or can be have multiple cycles of bends between the bridge of the staple with the compressing portion at the end of the OTC device. The bending portion can be single or double, the double bends being in cycle, out of cycle, mirror-symmetrical, to name a few. The bends can be double-sinusoidal as shown in  FIGS. 8, 9, and 11  The OTC device can be contained entirely between the two legs of the staple or can encircle one or both of the legs and, thereby, use the legs as a guide, for example, a sliding guide. The leg encirclement by the OTC device can be single or multiple. Travel of the OTC device can be limited, for example, by a star washer. The OTC device can be a compression spring(s) and a plate(s), with the plate encircling the legs and sliding thereon. The OTC device can be a compressible material secured on the legs. This material can be in the shape of a plate or a pillow. 
     With the foregoing and other objects in view, there is provided, in accordance with the invention, a substantially U-shaped staple having a bridge, legs, and an internally disposed compression device having a bias portion with a compression surface movably disposed between the legs and a compression resistor connected to the bridge and to the compression surface and is formed to resist movement of the compression surface towards the bridge with a force. 
     In accordance with another feature of the invention, the bridge is substantially rod-shaped with ends and the base end of each of the legs is integral with a respective one of the ends. 
     In accordance with a further feature of the invention, the bridge and legs define a bridge-leg plane and the legs extend from the bridge at an angle of between 80 and 100 degrees in the bridge-leg plane. 
     In accordance with an additional feature of the invention, the compression surface defines two orifices and each of the legs extends through one of the two orifices. 
     In accordance with yet another feature of the invention, the compression resistor defines at least one orifice pair, the compression surface defines two orifices, and each of the legs extends through one of the two orifices and one of the at least one orifice pair. 
     In accordance with yet a further feature of the invention, the compression resistor defines a plurality of orifice pairs, the compression surface defines two orifices, and each of the legs extends through one of the two orifices and one of each of the orifice pairs. 
     In accordance with yet an added feature of the invention, the bridge and the legs define a compression axis and the compression surface is movably disposed between the legs along the compression axis. 
     In accordance with yet an additional feature of the invention, the compression device is connected to the bridge. 
     In accordance with again another feature of the invention, the compression resistor connects the bridge to the compression surface. 
     In accordance with again a further feature of the invention, the bridge, the legs, the compression resistor, and the compression surface are integral. 
     In accordance with again an added feature of the invention, the compression resistor is at least partly disposed between the legs. 
     In accordance with again an additional feature of the invention, the compression resistor is disposed between the bridge and the compression surface. 
     In accordance with still another feature of the invention, the force is a pre-defined opposing force. 
     In accordance with still a further feature of the invention, the force is a substantially constant force. 
     In accordance with still an added feature of the invention, the force is a linearly increasing force. 
     In accordance with still an additional feature of the invention, the compression resistor has an anti-compressive spring constant imparting a substantially constant anti-compressive force over a pre-defined compression range. 
     In accordance with another feature of the invention, the staple and the compression device are of a biocompatible material. 
     In accordance with a further feature of the invention, the compression surface and the legs define a central compression region in which is to be disposed a material to be compressed between the compression surface and stapling points when distal ends of the staple legs are deformed. When the distal ends are deformed in a staple closing direction into the central compression region, the bias portion resists movement of the compression surface in the staple closing direction with a pre-defined, substantially constant force. 
     In accordance with an added feature of the invention, the compression surface and the bias portion are shaped to impart a pre-defined, substantially constant bias force upon material disposed between the compression surface and stapling points when the stapling points are deformed. 
     In accordance with a concomitant feature of the invention, when stapling points are deformed toward one another, material disposed between the compression surface and the stapling points is compressed between the stapling points and the compression surface. The compression resistor maintains a substantially constant compressive force on the material within a pre-defined range independent of a degree of compression between stapling points and the compression surface. 
     Although the invention is illustrated and described herein as embodied in an adjustable compression staple and method for stapling with adjustable compression, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. Additionally, well-known elements of exemplary embodiments of the invention will not be described in detail or will be omitted so as not to obscure the relevant details of the invention. 
     Other features that are considered as characteristic for the invention are set forth in the appended claims. As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one of ordinary skill in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the invention. While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the drawing figures. The figures of the drawings are not drawn to scale. 
     Before the present invention is disclosed and described, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The terms “a” or “an”, as used herein, are defined as one or more than one. The term “plurality,” as used herein, is defined as two or more than two. The term “another,” as used herein, is defined as at least a second or more. The terms “including” and/or “having,” as used herein, are defined as comprising (i.e., open language). The term “coupled,” as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically. 
     As used herein, the term “about” or “approximately” applies to all numeric values, whether or not explicitly indicated. These terms generally refer to a range of numbers that one of skill in the art would consider equivalent to the recited values (i.e., having the same function or result). In many instances these terms may include numbers that are rounded to the nearest significant figure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Advantages of the embodiments of the present invention will be apparent from the following detailed description of the preferred embodiments thereof, which description should be considered in conjunction with the accompanying drawings in which: 
         FIG. 1  is a perspective view from above a side of an exemplary prior art surgical staple; 
         FIG. 2  is a perspective view from above a side of a first exemplary embodiment of an OTC staple according to the invention; 
         FIG. 3  is a perspective view from above a side of a second exemplary embodiment of an OTC staple according to the invention; 
         FIG. 4  is a perspective view from above a side of a third exemplary embodiment of an OTC staple according to the invention; 
         FIG. 5  is a perspective view from above a side of a fourth exemplary embodiment of an OTC staple according to the invention; 
         FIG. 6  is a perspective view from above a side of a fifth exemplary embodiment of an OTC staple according to the invention; 
         FIG. 7  is a perspective view from above a side of a sixth exemplary embodiment of an OTC staple according to the invention; 
         FIG. 8  is a perspective view from above a side of a seventh exemplary embodiment of an OTC staple according to the invention; 
         FIG. 9  is a perspective view from above a side of an eighth exemplary embodiment of an OTC staple according to the invention; 
         FIG. 10  is a perspective view from above a side of a ninth exemplary embodiment of an OTC staple according to the invention; 
         FIG. 11  is a perspective view from above a side of a tenth exemplary embodiment of an OTC staple according to the invention; 
         FIG. 11A  is a fragmentary, enlarged perspective view from below a side of the OTC staple of  FIG. 11 ; 
         FIG. 12  is a perspective view from above a side of an eleventh exemplary embodiment of an OTC staple according to the invention; 
         FIG. 13  is a perspective view from above a side of a twelfth exemplary embodiment of an OTC staple according to the invention; 
         FIG. 14  is a perspective view from above a side of a thirteenth exemplary embodiment of an OTC staple according to the invention; 
         FIG. 15  is a perspective view from above a side of a fourteenth exemplary embodiment of an OTC staple according to the invention; 
         FIG. 16  is a perspective view from above a side of a fifteenth exemplary embodiment of an OTC staple according to the invention; 
         FIG. 17  is a side elevational view of the prior art surgical staple of  FIG. 1  with the staple tips illustrating an exemplary range of stapling; 
         FIG. 18  is a side elevational view of the staple of  FIG. 6  with the staple tips in a first intermediate position of an exemplary stapling range; 
         FIG. 19  is a side elevational view of the staple of  FIG. 6  with the staple tips in a second intermediate position of an exemplary stapling range; and 
         FIG. 20  is a side elevational view of the staple of  FIG. 6  with the staple tips in a third intermediate position of an exemplary stapling range. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Herein various embodiment of the present invention are described. In many of the different embodiments, features are similar. Therefore, to avoid redundancy, repetitive description of these similar features may not be made in some circumstances. It shall be understood, however, that description of a first-appearing feature applies to the later described similar feature and each respective description, therefore, is to be incorporated therein without such repetition. 
     Referring now to the figures of the drawings in detail and first, particularly to  FIG. 2  thereof, there is shown a first exemplary embodiment of an automatic optimal tissue compression (OTC) staple  20  according to the invention. In this first embodiment, the bridge  21  has a center bridge portion  22  and an extension  23  that substantially increases the overall length of the bridge  21 —as compared to the bridge  2  of the staple  1  of  FIG. 1 . As the upper bridge portion  22  transitions into the extension  23 , it curves into and within the central region  24  of the staple  20 . This extension  23  can be in any shape or of any material so long as it delivers a pre-set compressive force to the tissue at a compressing portion  25 , and as long as it allows for absorption (within the area between the compressing portion  25  and the upper bridge portion  22 ) of forces greater than this pre-set force. Therefore, the shape can be trapezoidal, triangular, sinusoidal, or any other configuration. An exemplary embodiment of relatively sinusoidal curves is shown in  FIG. 2 . These curves traverse two periods in the illustrated embodiment, however, the number of wave periods can be varied (smaller or larger). The extension  23  has two mirror-symmetrical portions each starting from the upper bridge portion  22  and ending at respective ends of the compressing portion  25 . Further, it is noted that neither the extension  23  nor the compressing portion  25  directly contacts the legs  26  in this exemplary configuration. 
     In the embodiment of  FIG. 2 , the extension  26  and the compressing portion  29  are integral with the upper bridge portion  22  and a base end  27  of the legs  26 . The legs  26  are shown as relatively circular in cross-section. The bridge  21  and all of the compressing components  22 ,  23 ,  25  can also be circular in cross-section. Alternatively, as shown in  FIG. 2 , any portion of the extension  23  and/or the compressing portion  25  can have different cross-sectional shapes, such as ovular, rectangular, or polygonal. In the embodiment shown, the cross-section of the extension  23  after the first curve away from the upper bridge portion  22  is shaped in a “racetrack” form (two relatively straight sides with two curved ends connecting each end of the sides). The upper bridge portion  22  can also have a different cross-sectional shape. The extension  23  and compressing portion  25  are, in this embodiment, even in cross-sectional area. Different portions of these parts can, however, have varying cross-sectional areas (i.e., varying thicknesses) as desired. 
     When the upper bridge  22 , the extension  23 , and the compressing portion  25  are shaped to deliver the pre-set compressive force to the tissue in a substantially longitudinal direction  28  of an unbent section of the leg portions  26  and to absorb forces greater than this pre-set force, the overall effect is to create an OTC device having a given spring coefficient. In other words, the OTC device maintains the preset compressive force within the stapled area even after tissue changes states, such as expanding due to swelling and/or contracting during desiccation. Variation of the cross-section of any portion of the upper bridge  22 , the extension  23 , and the compressing portion  25  will allow for different OTC spring coefficients and, therefore, allows for adjustment of the compressive and reactive force constants of the OTC device within the staple  20 . Variation of the material making up all of the staple  20  or any of its portions also permits adjustment of the OTC force. 
       FIG. 3  illustrates a second exemplary embodiment of the OTC staple  30  according to the invention. In this variation, as compared to the embodiment of  FIG. 2 , the OTC portion is not integral with the bridge  31  and the legs  32 . Instead, the OTC device  33  is separate therefrom and is connected to these staple portions. Specifically, the OTC device  33  has a compressing portion  34  that directly contacts the tissue being compressed and an extension  36  for providing the load-bearing force when tissue is compressed within the central region  37  of the staple  30 . The OTC device  33  also has a connecting portion  35  for attaching the OTC device  33  to the bridge  31 . The extension  36  connects the upper and lower portions  34 ,  35  of the OTC device  33 . The extension  33  and the compressing portion  34  are, in this embodiment, different in cross-sectional area. Here, the cross-sectional area of the compressing portion  34  is wider than the extension  36 . Any portions of the extension  33  or the compressing portion  34  can be varied to have same or varying cross-sectional areas (i.e., varying thicknesses). 
     Connection of the OTC device  33  to the staple, for example, at the bridge  31 , can occur by any fastening measure. One exemplary connection method is spot welding, which is indicated in  FIG. 3  by reference numeral  38 . Other exemplary methods of attaching suitable materials together include soldering and brazing. The type or types of material of the staple portions  31 ,  32  and the OTC device  33  will direct a preferable attachment method. In the case of attaching two materials together that are not suited to be welded, soldered or brazed, other attachment methods can be used such as crimping and adhesive bonding. Features can be added to one or both of the two components to facilitate the crimp or bond. These features could be configured to have the components snap together. In the case of dissimilar materials, for example, if the staple material is stainless steel and the OTC device  33  is of nickel titanium alloy, then preferred attachment measures include crimping, adhesive bonding, or snapping. 
     In this second embodiment, the OTC device  33  behaves similar to the OTC portions of the embodiment of  FIG. 2  and can be shaped with the same variations of cross-section and other spatial characteristics and can be formed with the same variations in material composition. Variation of any attribute of the OTC device  33  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue. The extension  36  can be any shape or material so long as it delivers a pre-set compressive force to the tissue at the compressing portion  34  and as long as it allows for absorption of forces greater than this pre-set force. An exemplary embodiment selected for this exemplary OTC device  33  is a relatively sinusoidal set of curves traversing less than two periods. The extension  36  has two mirror-symmetrical portions each starting from the bridge  31  and ending at respective ends of the compressing portion  34 . In this exemplary embodiment, neither the extension  36  nor the compressing portion  34  directly contacts the legs  32 . Most of the cross-section of the OTC device  33  has a racetrack form. Like the embodiment of  FIG. 2 , the cross-section can be varied in any desired way to deliver the pre-set compressive force to the tissue and to absorb forces greater than this pre-set force. 
       FIG. 4  illustrates a third exemplary embodiment of the OTC staple  40  according to the invention. In this variation, as compared to the embodiments of  FIGS. 2 and 3 , the OTC portion  43  is not symmetrical with respect to the bridge  41  or the legs  42 . Also, like the embodiment of  FIG. 3 , the OTC portion is not integral with either the bridge  41  or the legs  42 . The OTC device  43  is a separate part from the bridge  41  and the legs  42  and is fixedly connected to the bridge  41  at a connection location (for example, with a spot weld  48 ; other fixation/connection processes can be used). In particular, a connecting portion  45  of the OTC device  43  fixedly secures the OTC device  43  to the bridge  41 . An extension  46  of the OTC device  43  provides the load-bearing force when tissue is compressed within the central region  47  of the staple  40  and a compressing portion  44  directly contacts the tissue being compressed. 
     Notably different from the embodiments of  FIGS. 2 and 3  is the compressing portion  44 . Here, the width of the compressing portion  44  (defined along the line between the two legs  42  of the staple  40 ) is greater than the separation distance of the two legs  42 . The compressing portion  44  is provided with orifices  49  having a shape substantially corresponding to the cross-sectional shape of the upper portion of the staple legs  42  but slightly larger. The legs  42  pass through and slidably rest within these orifices  49 . In such a configuration, movement of the OTC device  43  out of the bridge-legs plane is substantially prevented. Because the orifices  49  are shaped to be slightly larger than the cross-section of the legs  42 , the extension  46  acts as a compression spring in the bridge-legs plane as the compressing portion  44  moves up and down along the upper portion of the legs  42  (up being defined as the direction towards the bridge  41  from the piercing tips of the legs  42 ). Thus, the OTC device  43  of the third embodiment behaves different from the OTC devices of  FIGS. 2 and 3  because of the form-locking and sliding connection between the connecting portion  44  and the legs  42 . A form-locking connection is one that connects two elements together due to the shape of the elements themselves, as opposed to a force-locking connection, which locks the elements together by force external to the elements. 
     Like the previous embodiments, the OTC device  43  can be shaped with variations in cross-section and other spatial characteristics and can be formed with a variety of material compositions. The extension  46  and compressing portion  44  are, in this embodiment, different in cross-sectional area. Here, the cross-sectional area of the compressing portion  44  is wider than the extension  46 . Any portions of the extension  46  or the compressing portion  44  can be varied to have same or varying cross-sectional areas (i.e., varying thicknesses). The extension  46  can be any shape or material so long as it delivers the pre-set compressive force to the tissue at the compressing portion  44  and as long as it allows for absorption of forces greater than this pre-set force. An exemplary embodiment selected for this OTC device  43  is a relatively sinusoidal curve traversing approximately one sinusoidal period. Virtually all of the cross-section of the OTC device  43  has a racetrack form, but can be changed as desired to other shapes (e.g., circular, ovular, polygonal, etc.). As described above, variation of any attribute of the OTC device  43  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue in the central region  47 . 
       FIG. 5  illustrates a fourth exemplary embodiment of the OTC staple  50  according to the invention. This variation has some of the features of the above embodiments. In this variant, like the embodiment of  FIG. 2 , the OTC portion is symmetrical with respect to the bridge  51  and the legs  52  and the OTC device  53  is integral with the bridge  51 . Like the embodiment of  FIG. 4 , the compressing portion  54  has a width greater than the separation distance of the two legs  52  and has ports  55  with a shape substantially corresponding to the cross-sectional shape of the upper portion of the legs  52 , but slightly larger. The legs  52  pass through these ports  55 . In this configuration, movement of the OTC device  53  out of the bridge-legs plane is substantially prevented. The extension  56  of the OTC device  53  traverses from the bridge  51  to the compressing portion  54 . Because the ports  55  are shaped to be slightly larger than the cross-section of the legs  52 , the extension  56  acts as a compression spring in the bridge-legs plane as the compressing portion  54  moves up and down along the upper portion of the legs  52 . It is the extension  56  that provides the load-bearing force when tissue is compressed within the central region  57  of the staple  50 . Because of the form-locking and sliding connection between the compressing portion  54  and the legs  52 , the OTC device  53  of the fourth embodiment behaves similar to the OTC devices of  FIG. 4 . 
     Here, the OTC device  53  is integral with the legs  52 , the bridge  51 , and the compressing portion  54 . Because the two sides of the bridge  51  are not integral, they can separate from one another when the staple  50  is subjected to a twisting force. If desired, to substantially prevent such separation, the central portions of the bridge  51  can be fixedly connected to one another at a connection location (for example, with a spot weld  58 ; other connection processes can be used as well). 
     Like the previous embodiments, the OTC device  53  can be shaped with variations in cross-section and other spatial characteristics and can be formed with a variety of material compositions. Any portions of the extension  56  or the compressing portion  54  can be varied to have the same or varying cross-sectional areas (i.e., varying thicknesses). The extension  56  and compressing portion  54  are, in this embodiment, different in cross-sectional areas. Here, the cross-sectional area of the upper majority of the extension  56  is narrower than the lower portion of the extension  56  and the cross-section of the lower portion of the extension  56  gradually increases in width until it is equal to the cross-section of the compressing portion  54 . 
     The extension  56  can be any shape or material so long as it delivers the pre-set compressive force to the tissue at the compressing portion  54  and as long as it allows for absorption of forces greater than this pre-set force. An exemplary embodiment selected for this OTC device  53  is a relatively sinusoidal curve traversing more than one sinusoidal period. Again, only for illustrative purposes, the cross-section of the OTC device  53  has a racetrack shape, but can be changed as desired to other shapes (e.g., circular, ovular, polygonal, etc.). As described above, variation of any attribute of the OTC device  53  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue in the central region  57 . 
       FIG. 6  illustrates a fifth exemplary embodiment of the OTC staple  60  according to the invention. This variation has some of the features of the above embodiments. In this variant, like the embodiment of  FIG. 3 , the OTC portion is symmetrical with respect to the bridge  61  and the legs  62  and the OTC device  63  is a separate part from the bridge  61  and legs  62  of the staple  60 . Like the embodiment of  FIGS. 4 and 5 , the compressing portion  64  has a width greater than the separation distance of the two legs  62  and has ports  65  with a shape substantially corresponding to the cross-sectional shape of the upper portion of the legs  62 , but slightly larger. The legs  62  pass through these ports  65 . In this configuration, movement of the OTC device  63  out of the bridge-legs plane is substantially prevented. The extension  66  of the OTC device  63  traverses from the bridge  61  to the compressing portion  64 . Because the ports  65  are shaped to be slightly larger than the cross-section of the legs  62 , the extension  66  acts as a compression spring in the bridge-legs plane as the compressing portion  64  moves up and down along the upper portion of the legs  62 . It is the extension  66  that provides the load-bearing force when tissue is compressed within the central region  67  of the staple  60 . Because of the form-locking and sliding connection between the compressing portion  64  and the legs  62 , the OTC device  63  of the fifth embodiment behaves similar to the OTC devices of  FIGS. 4 and 5 . 
     Connection of the OTC device  63  to the staple  60 , for example, at the bridge  61 , can occur by any fastening measure. One exemplary connection method is spot welding, which is indicated in  FIG. 6  by reference numeral  68 . The type or types of material of the staple portions  61 ,  62  and the OTC device  63  will direct a preferable attachment method. In the case of attaching two materials together that are not suited to be welded, soldered or brazed, other attachment methods can be used such as crimping and adhesive bonding. Features can be added to one or both of the two components to facilitate the crimp or bond. These features could be configured to have the components snap together. In the case of dissimilar materials, for example, if the staple material is stainless steel and the OTC device  63  is of nickel titanium alloy, then preferred attachment measures include crimping, adhesive bonding, or snapping. 
     Like the previous embodiments, the OTC device  63  can be shaped with variations in cross-section and other spatial characteristics and can be formed with a variety of material compositions. Any portions of the extension  66  or the compressing portion  64  can be varied to have the same or different cross-sectional areas (i.e., varying thicknesses). The extension  66  and compressing portion  64  are, in this embodiment, different in cross-sectional areas. Here, the cross-sectional area of most of the extension  66  is narrower than the lowermost portion of the extension  66  and the cross-section of this lowermost portion of the extension  66  gradually increases in width until it is equal to the cross-section of the compressing portion  64 , which is substantially wider. 
     The extension  66  can be any shape or material so long as it delivers the pre-set compressive force to the tissue at the compressing portion  64  and as long as it allows for absorption of forces greater than this pre-set force. An exemplary embodiment selected for this OTC device  63  is a relatively sinusoidal curve traversing more than one sinusoidal period. Again, only for illustrative purposes, the cross-section of the OTC device  63  has a racetrack shape, but can be changed as desired to other shapes (e.g., circular, ovular, polygonal, etc.). As described above, variation of any attribute of the OTC device  63  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue in the central region  67 . 
       FIG. 7  illustrates a sixth exemplary embodiment of the OTC staple  70  according to the invention. This variation has some of the features of the above embodiments. In this variant, like the embodiment of  FIG. 3 , the OTC portion is symmetrical with respect to the bridge  71  and the legs  72  and the OTC device  73  is a separate part from the bridge  71  and legs  72  of the staple  70 . Like the embodiment of  FIGS. 4 to 6 , the compressing portion  74  has a width greater than the separation distance of the two legs  72  and has ports  75  with a shape substantially corresponding to the cross-sectional shape of the upper portion of the legs  72 , but slightly larger. The legs  72  pass through these ports  75 . In this configuration, movement of the OTC device  73  out of the bridge-legs plane is substantially prevented. The extension  76  of the OTC device  73  traverses from the bridge  71  to the compressing portion  74 . Because the ports  75  are shaped to be slightly larger than the cross-section of the legs  72 , the extension  76  acts as a compression spring in the bridge-legs plane as the compressing portion  74  moves up and down along the upper portion of the legs  72 . It is the extension  76  that provides the load-bearing force when tissue is compressed within the central region  77  of the staple  70 . Because of the form-locking and sliding connection between the compressing portion  74  and the legs  72 , the OTC device  73  of the sixth embodiment behaves similar to the OTC devices of  FIGS. 4 to 6 . 
     Connection of the OTC device  73  to the staple  70 , for example, at the bridge  71 , can occur by any fastening measure. One exemplary connection method is spot welding, which is indicated in  FIG. 7  by reference numeral  78 . The type or types of material of the staple portions  71 ,  72  and the OTC device  73  will direct a preferable attachment method. In the case of attaching two materials together that are not suited to be welded, soldered or brazed, other attachment methods can be used such as crimping and adhesive bonding. Features can be added to one or both of the two components to facilitate the crimp or bond. These features could be configured to have the components snap together. In the case of dissimilar materials, for example, if the staple material is stainless steel and the OTC device  73  is of nickel titanium alloy, then preferred attachment measures include crimping, adhesive bonding, or snapping. 
     It is noted that the extensions (i.e., springs) in each of  FIGS. 2, 3, 5, and 6  are in the same plane, which can be the bridge-legs plane (as shown) or out of that plane. In comparison to these embodiments, the extension  76  has the springs residing in different planes (i.e., one next to the other. 
     Like the previous embodiments, the OTC device  73  can be shaped with variations in cross-section and other spatial characteristics and can be formed with a variety of material compositions. Any portions of the extension  76  or the compressing portion  74  can be varied to have the same or varying cross-sectional areas (i.e., varying thicknesses). The extension  76  and the compressing portion  74  are, in this embodiment, different in cross-sectional areas. Here, the cross-sectional area of most of the extension  76  is narrower than the lowermost portion of the extension  76  and the cross-section of this lowermost portion of the extension  76  gradually increases in width until it is equal to the cross-section of the compressing portion  74 , which is substantially wider. 
     The extension  76  can be any shape or material so long as it delivers the pre-set compressive force to the tissue at the compressing portion  74  and as long as it allows for absorption of forces greater than this pre-set force. An exemplary embodiment selected for this OTC device  73  is a relatively sinusoidal curve traversing more than one sinusoidal period. Again, only for illustrative purposes, the cross-section of the OTC device  73  has a racetrack shape, but can be changed as desired to other shapes (e.g., circular, ovular, polygonal, etc.). As described above, variation of any attribute of the OTC device  73  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue in the central region  77 . 
       FIG. 8  illustrates a seventh exemplary embodiment of the OTC staple  80  according to the invention. This variation has some of the features of the above embodiments. In this variant, like the embodiment of  FIG. 3 , the OTC portion is symmetrical with respect to the bridge  81  and the legs  82 , and the OTC device  83  is a separate part from the bridge  81  and legs  82  of the staple  80 . Like the embodiment of  FIGS. 4 to 7 , the compressing portion  84  has a width greater than the separation distance of the two legs  82  and has ports  85  with a shape substantially corresponding to the cross-sectional shape of the upper portion of the legs  82 , but slightly larger. The legs  82  pass through these ports  85 . In this configuration, movement of the OTC device  83  out of the bridge-legs plane is substantially prevented. The extension  86  of the OTC device  83  traverses from the bridge  81  to the compressing portion  84 . Because the ports  85  are shaped to be slightly larger than the cross-section of the legs  82 , the extension  86  acts as a compression spring in the bridge-legs plane as the compressing portion  84  moves up and down along the upper portion of the legs  82 . It is the extension  86  that provides the load-bearing force when tissue is compressed within the central region  87  of the staple  80 . Because of the form-locking and sliding connection between the compressing portion  84  and the legs  82 , the OTC device  83  of the seventh embodiment behaves similar to the OTC devices of  FIGS. 4 to 7 . 
     Like the previous embodiments, the OTC device  83  can be shaped with variations in cross-section and other spatial characteristics and can be formed with a variety of material compositions. Any portions of the extension  86  or the compressing portion  84  can be varied to have the same or varying cross-sectional areas (i.e., varying thicknesses). The extension  86  and the compressing portion  84  are, in this embodiment, different in cross-sectional areas. Here, the cross-sectional area of most of the extension  86  is smaller and narrower than the lowermost portion of the extension  86  and the cross-section of this lowermost portion gradually increases in width until it is equal to the cross-section of the compressing portion  84 , which is substantially wider. Also, the cross-sectional area of this extension  86  is smaller than previous embodiments (but it need not be). 
     The extension  86  can be any shape or material so long as it delivers the pre-set compressive force to the tissue at the compressing portion  84  and as long as it allows for absorption of forces greater than this pre-set force. An exemplary embodiment selected for this OTC device  83  is a relatively sinusoidal curve traversing a more than two periods and also having a second “interior” curve that traverses sinusoidal periods. In this embodiment, the OTC device  83  has an uppermost portion that is, in contrast to the embodiments of  FIGS. 3, 6, and 7  a single bar extending along a majority of the bridge  81 . 
     Connection of the OTC device  83  to the staple  80 , for example, at the bridge  81 , can occur by any fastening measure. One exemplary connection method is spot welding, which is indicated in  FIG. 8  by reference numeral  88 . Because there is contact over most of the bridge  81 , the OTC device  83  can be welded over the entire length thereof. The type or types of material of the staple portions  81 ,  82  and the OTC device  83  will direct a preferable attachment method. In the case of attaching two materials together that are not suited to be welded, soldered or brazed, other attachment methods can be used such as crimping and adhesive bonding. Features can be added to one or both of the two components to facilitate the crimp or bond. These features could be configured to have the components snap together. In the case of dissimilar materials, for example, if the staple material is stainless steel and the OTC device  83  is of nickel titanium alloy, then preferred attachment measures include crimping, adhesive bonding, or snapping. 
     Only for illustrative purposes, the cross-section of the OTC device  83  has a racetrack shape, but can be changed as desired to other shapes (e.g., circular, ovular, polygonal, etc.). As described above, variation of any attribute of the OTC device  83  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue in the central region  87 . 
       FIG. 9  illustrates an eighth exemplary embodiment of the OTC staple  90  according to the invention. This variation has some of the features of the above embodiments. In this variant, like the embodiment of  FIG. 3 , the OTC portion is symmetrical with respect to the bridge  91  and the legs  92 , and the OTC device  93  is a separate part from the bridge  91  and legs  92  of the staple  90 . Like the embodiment of  FIGS. 4 to 8 , the compressing portion  94  has a width greater than the separation distance of the two legs  92  and has ports  95  with a shape substantially corresponding to the cross-sectional shape of the upper portion of the legs  92 , but slightly larger. The legs  92  pass through these ports  95 . In this configuration, movement of the OTC device  93  out of the bridge-legs plane is substantially prevented. The extension  96  of the OTC device  93  traverses from the bridge  91  to the compressing portion  94 . Because the ports  95  are shaped to be slightly larger than the cross-section of the legs  92 , the extension  96  acts as a compression spring in the bridge-legs plane as the compressing portion  94  moves up and down along the upper portion of the legs  92 . It is the extension  96  that provides the load-bearing force when tissue is compressed within the central region  97  of the staple  90 . Because of the form-locking and sliding connection between the compressing portion  94  and the legs  92 , the OTC device  93  of the eighth embodiment behaves similar to the OTC devices of  FIGS. 4 to 8 . 
     Like the previous embodiments, the OTC device  93  can be shaped with variations in cross-section and other spatial characteristics and can be formed with a variety of material compositions. Any portion(s) of the extension  96  or the compressing portion  94  can be varied to have the same or varying cross-sectional areas (i.e., varying thicknesses). The extension  96  and the compressing portion  94  are, in this embodiment, different in cross-sectional areas. Here, the cross-sectional area of most of the extension  96  is smaller and narrower than the lowermost portion of the extension  96  and the cross-section of this lowermost portion gradually increases in width until it is equal to the cross-section of the compressing portion  94 , which is substantially wider. Also, the cross-sectional area of this extension  96  is smaller than previous embodiments (but need not be). With such a relatively smaller cross-sectional shape, the curves of the extension  96  might tend to deform or move out of the bridge-legs plane, which tendency can increase or decrease depending upon the material of the extension  96 . To prevent such deformation and/or movement, a plurality of guiding tabs  99  are disposed at one or more of the outside ends of each periodic curve adjacent the legs  92 . These guiding tabs  99  are shaped in a similar manner to the ends of the compressing portion  94 , in that they have ports with a cross-sectional shape substantially corresponding to the cross-sectional shape of the upper portion of the legs  92  but slightly larger. The embodiment illustrated in  FIG. 9  provides each guiding tab  99  with two relatively parallel plates each having one of the two ports through which the respective leg  92  is disposed Like the lower portion of the extension  96 , the cross-sectional area of the extension gradually increases in width until it is equal to the larger cross-section of the plate of the guiding tab  99 . Another alternative of the guiding tab  99  is to have only a single plate with a single port. In such an embodiment (assuming the material was the same as a dual-plate embodiment), the curves of the extension  96  would be slightly stiffer because of the absence of the exterior curve of the guiding tab  99 . 
     The extension  96  can be any shape or material so long as it delivers the pre-set compressive force to the tissue at the compressing portion  94  and as long as it allows for absorption of forces greater than this pre-set force. An exemplary embodiment selected for this OTC device  93  is a relatively sinusoidal curve having a second interior curve that traverses a few sinusoidal periods and, in this embodiment, has an uppermost portion that is, like the embodiment of  FIG. 8 , a single bar extending along a majority of the bridge  91 . Connection of the OTC device  93  to the staple  90 , for example, at the bridge  91 , can occur by any fastening measure. One exemplary connection method is spot welding, which is indicated in  FIG. 9  by reference numeral  98 . Alternatively, the weld can be over the entire span contacting the bridge  91 . The type or types of material of the staple portions  91 ,  92  and the OTC device  93  will direct a preferable attachment method. In the case of attaching two materials together that are not suited to be welded, soldered or brazed, other attachment methods can be used such as crimping and adhesive bonding. Features can be added to one or both of the two components to facilitate the crimp or bond. These features could be configured to have the components snap together. In the case of dissimilar materials, for example, if the staple material is stainless steel and the OTC device  93  is of nickel titanium alloy, then preferred attachment measures include crimping, adhesive bonding, or snapping. 
     Again, only for illustrative purposes, the cross-section of the OTC device  93  has a racetrack shape, but can be changed as desired to other shapes (e.g., circular, ovular, polygonal, etc.). As described above, variation of any attribute of the OTC device  93  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue in the central region  97 . 
       FIG. 10  illustrates a ninth exemplary embodiment of the OTC staple  100  according to the invention. This variation has some of the features of the above embodiments. In this variant, like the embodiment of  FIG. 3 , the OTC portion is symmetrical with respect to the bridge  101  and the legs  102 , and the OTC device  103  is a separate part from the bridge  101  and legs  102  of the staple  100 . The compressing portion  104 , however, is unlike all of the previous embodiments. Here, the compressing portion  104  is formed from two compressing plates, each of these plates being attached to a respective lower end of two halves of the OTC device  103 . The shape of the compressing portion  104  need not be a plate. It can be cylindrical, for example. Like previous embodiments, the lowermost end of the extension  106  gradually increases in cross-section until it is equal to the compressing portion  104 . Each compressing plate, then, extends towards a respective one of the legs  102  and defines a respective port  105  for receiving therein the leg  102 . The port  105  has a shape substantially corresponding to the cross-sectional shape of the upper portion of the legs  102 , but is slightly larger. The legs  102  pass through each port  105  to form the OTC device  103 . In this configuration, movement of the OTC device  103  out of the bridge-legs plane is substantially prevented. The extension  106  of the OTC device  103  traverses from the bridge  101  to the plates of the compressing portion  104 . Because the ports  105  are shaped to be slightly larger than the cross-section of the legs  102 , the extension  106  acts as a compression spring in the bridge-legs plane as the compressing portion  104  moves up and down along the upper portion of the legs  102 . It is the extension  106  that provides the load-bearing force when tissue is compressed within the central region  107  of the staple  100 . 
     In this embodiment, as compared to previous OTC device embodiments, the two sides of the OTC device  103  move independent from one another. Thus, if tissue varies in any characteristic within the central portion  107  (e.g., hardness, thickness, density), the optimal tissue compression force can be delivered independently and differently for each of the two differing tissue segments contacting the respective one of the sides of the OTC device  103 . 
     Connection of the OTC device  103  to the staple  100 , for example, at the bridge  101 , can occur by any fastening measure. One exemplary connection method is spot welding, which is indicated in  FIG. 10  by reference numeral  108 . As the upper portion contacts almost all of the bridge  101 , the weld  108 , instead, can span any amount of the bridge  101 . The type or types of material of the staple portions  101 ,  102  and the OTC device  103  will direct a preferable attachment method. In the case of attaching two materials together that are not suited to be welded, soldered or brazed, other attachment methods can be used such as crimping and adhesive bonding. Features can be added to one or both of the two components to facilitate the crimp or bond. These features could be configured to have the components snap together. In the case of dissimilar materials, for example, if the staple material is stainless steel and the OTC device  103  is of nickel titanium alloy, then preferred attachment measures include crimping, adhesive bonding, or snapping. 
     Like the previous embodiments, the OTC device  103  can be shaped with variations in cross-section and other spatial characteristics and can be formed with a variety of material compositions. Any portions of the extension  106  or the compressing portion  104  can be varied to have the same or varying cross-sectional areas (i.e., varying thicknesses). The extension  106  and the plates of the compressing portion  104  are, in this embodiment, different in cross-sectional areas. Here, the cross-sectional area of most of the extension  106  is smaller and narrower than the lowermost portion of the extension  86  and the cross-section of this lowermost portion gradually increases in width until it is equal to the cross-section of the respective plate of the compressing portion  104 , which is substantially wider. 
     The extension  106  can be any shape or material so long as it delivers the pre-set compressive force to the tissue at the compressing portion  104  and as long as it allows for absorption of forces greater than this pre-set force. An exemplary embodiment selected for this OTC device  103  is a relatively sinusoidal curve having almost two sinusoidal periods and, in this embodiment, has an uppermost portion that is (like the embodiments of  FIGS. 8 and 9 ) a single bar extending along a majority of the bridge  101 . For illustrative purposes, the cross-section of the OTC device  103  has an ovular shape, but can be changed as desired to other shapes (e.g., circular, racetrack, polygonal, etc.). As described above, variation of any attribute of the OTC device  103  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue in the central region  107 . 
       FIGS. 11 and 11A  illustrate a tenth exemplary embodiment of the OTC staple  110  according to the invention. This variation has some of the features of the above embodiments. In this variant, like the embodiment of  FIG. 3 , the OTC portion is symmetrical with respect to the bridge  111  and the legs  112 , and the OTC device  113  is a separate part from the bridge  111  and legs  112  of the staple  110 . The compressing portion  114  is like the embodiment of  FIG. 10 —it is formed from two compressing plates, each of these plates being attached to a respective lower end of two halves of the OTC device  113 . The lowermost end of the extension  116  gradually increases in cross-section until it is equal in area to the compressing portion  114 . Each compressing plate, then, extends towards a respective one of the legs  112  and defines a respective port  115  for receiving therein one of the legs  112 . In  FIG. 11 , the ports  115  cannot be seen because of the presence of one-way washers  119  (described below), but the port  115  is visible in  FIG. 11A . 
     As set forth above, each port  115  has a shape substantially corresponding to the cross-sectional shape of the upper portion of the legs  112  but is slightly larger. The legs  112  pass through each port  115  to form the OTC device  113 . Because the ports  115  are shaped to be slightly larger than the cross-section of the legs  112 , the extension  116  acts as a compression spring in the bridge-legs plane as the compressing portion  114  moves up and down along the upper portion of the legs  112 . In this configuration, movement of the OTC device  113  out of the bridge-legs plane is substantially prevented. It is the extension  116  that provides the load-bearing force when tissue is compressed within the central region  117  of the staple  110 . In this embodiment (like the embodiment of  FIG. 10 ), the two sides of the OTC device  113  move independent from one another. Thus, if tissue varies in any characteristic within the central portion  117  (e.g., hardness, thickness, density), the optimal tissue compression force can be delivered independently and differently for each of the two differing tissue segments contacting the two plates of the compressing portion  114 . 
     Introduced for the first time in this embodiment are one-way devices  119  (one exemplary embodiment being a star washer that is illustrated in  FIGS. 11 and 11A ) disposed on the leg  112  between the bridge  111  and the compressing portion  114 . These devices  119  are shaped to freely move on the leg  112  upwards towards the bridge  111  but not to move in the opposite direction. Thus, as tissue is being compressed within the central region  117  as the distal ends of the legs  112  are curved in the stapling action, the tissue presses against the compressing portion  114  and moves the compressing portion  114  up towards the bridge  111 . Once the stapling force is removed from the staple  110  (after stapling is complete), the tissue will most likely not press the washers  119  any further without any additionally supplied outside force. Thus, the washers  119  limit further movement of the compressing portion  114  from the then-current location of the washers  119  towards the first bend of the legs  112 . These washers also add some friction when the first stapling movement occurs, which friction may be used to add to and make up the compression coefficients of the OTC device  113 . If the stapled tissue swells, it is possible for the washers  119  to be moved if the force is sufficient. After such swelling ends and desiccation of the tissue occurs, the compressing portions  114  will be limited in further compression by these washers  119 . 
     Like the previous embodiments, the OTC device  113  can be shaped with variations in cross-section and other spatial characteristics and can be formed with a variety of material compositions. Any portions of the extension  116  or the compressing portion  114  can be varied to have the same or varying cross-sectional areas (i.e., varying thicknesses). The extension  116  and the plates of the compressing portion  114  are, in this embodiment, different in cross-sectional areas. Here, the cross-sectional area of most of the extension  116  is smaller and narrower than the lowermost portion of the extension  116  and the cross-section of this lowermost portion gradually increases in width until it is equal to the cross-section of the respective plate of the compressing portion  114 , which is substantially wider. 
     The extension  116  can be any shape or material so long as it delivers the pre-set compressive force to the tissue at the compressing portion  114  and as long as it allows for absorption of forces greater than this pre-set force. An exemplary embodiment selected for this OTC device  113  is a relatively sinusoidal curve traversing more than two sinusoidal periods and having a second “interior” curve. In this embodiment, the OTC device  113  has an uppermost portion that is (like the embodiments of  FIGS. 8 to 10 ) a single bar extending along a majority of the bridge  111 . Connection of the OTC device  113  to the staple  110 , for example, at the bridge  111 , can occur by any fastening measure. One exemplary connection method is spot welding, which is indicated in  FIG. 11  by reference numeral  118 . This process can be changed if desired. The type or types of material of the staple portions  111 ,  112  and the OTC device  113  will direct a preferable attachment method. In the case of attaching two materials together that are not suited to be welded, soldered or brazed, other attachment methods can be used such as crimping and adhesive bonding. Features can be added to one or both of the two components to facilitate the crimp or bond. These features could be configured to have the components snap together. In the case of dissimilar materials, for example, if the staple material is stainless steel and the OTC device  113  is of nickel titanium alloy, then preferred attachment measures include crimping, adhesive bonding, or snapping. 
     For illustrative purposes, the cross-section of the OTC device  113  has a racetrack shape, but can be changed as desired to other shapes (e.g., circular, ovular, polygonal, etc.). As described above, variation of any attribute of the OTC device  113  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue in the central region  117 . 
       FIG. 12  illustrates an eleventh exemplary embodiment of the OTC staple  120  according to the invention. This variation is significantly different from the above embodiments. The OTC device  123  is, as above, a separate part from the bridge  121  and legs  122  of the staple  120 . Here, however, the compressing portion  124  is a C-beam having ports  125  that permit passage of a respective one of the legs  122  therethrough. Each port  125  has a shape substantially corresponding to the cross-sectional shape of the upper portion of the legs  122  but is slightly larger. The legs  122  pass through each port  125  to form the OTC device  123 . In this configuration, movement of the OTC device  123  out of the bridge-legs plane is substantially prevented. 
     The C-beam shape is useful for a variety of reasons. First, the C-shape provides a central cavity in which a distal end of a compression device  126  can be held or fastened. Next, the C-shape also increases resistance to bending forces as compared to a simple rectangular plate, as is known in construction. Finally, orienting the open portion of the “C” away from the tissue presents a flat compressing plate to the tissue to be compressed. With such a shape, the tissue can be compressed evenly, with no singular pressure points. Of course, the C-shape is not the only possible cross-sectional shape. The compressing portion  124  can be a rectangular plate, an I-beam, an L-beam, or any other desired shape. 
     The compression device  126  can take any form (see, e.g.,  FIG. 13 ). The exemplary embodiment of  FIG. 12  illustrates the compression device  126  as a conically expanding compression spring. Connection of the spring  126  and compressing portion  124  to the staple  120 , for example, at the bridge  121 , can occur by any fastening measure. The illustrated exemplary proximal connection method is a ring of the spring material wrapping around the bridge  121 . This proximal end is secured at the center of the bridge  121  and held in place there by placing protuberances  128  on the bridge  121 . These protuberances prevent lateral movement of the proximal ring towards either of the two legs  122 . Of course, this ring can be welded or fastened to the bridge  121  by any fastening process. The distal end of the spring is a relatively circular coil lying in the same plane as the interior cavity of the C-beam and having an outer diameter just slightly less than the interior diameter of the C-shaped cavity of the compressing portion  124 . Thus, the ends of the C-shape can be used to retain the distal end of the spring  126  within the cavity. Of course, other fastening measures can be used to secure the spring distal ends to the compressing portion  124 . 
     It is the spring  126  that provides the load-bearing force when tissue is compressed within the central region  127  of the staple  120 . Like the previous embodiments, the OTC device  123  can be shaped with variations in cross-section, winding, and other spatial characteristics and can be formed with a variety of material compositions. Any portions of the spring  126  or the compressing portion  124  can be varied. In particular, the spring  126  can be any shape or material so long as it delivers the pre-set compressive force to the tissue through the compressing portion  124  and as long as it allows for absorption of forces greater than this pre-set force. As described above, variation of any attribute of the OTC device  123  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue in the central region  127 . 
       FIG. 13  illustrates a twelfth exemplary embodiment of the OTC staple  130  according to the invention. This variation is similar to the embodiment of  FIG. 12 . The OTC device  133  is, as above, a separate part from the bridge  131  and legs  132  of the staple  130  and the compressing portion  134  is a C-beam having ports  135  that permit passage of a respective one of the legs  132  therethrough. Each port  135  has a shape substantially corresponding to the cross-sectional shape of the upper portion of the legs  132  but is slightly larger. The legs  132  pass through each port  135  to form the OTC device  133 . In this configuration, movement of the OTC device  133  out of the bridge-legs plane is substantially prevented. 
     The C-beam shape has the same benefits as described in the eleventh embodiment of  FIG. 12 . Like that embodiment, the C-shape is not required; the compressing portion  134  can be a rectangular plate, an I-beam, an L-beam, or any other desired shape. 
     The compression device  136  can take any form. In the exemplary embodiment of  FIG. 13 , the compression device  136  is a pair of compression springs  136 . Connection of these springs  136  and the compressing portion  134  to the staple  130 , for example, at the bridge  131 , can occur by any fastening measure. The illustrated exemplary proximal connection method is a narrowing of the spring diameter to be equal or less than the diameter of the legs  132  at the connection point to the bridge  131 . Thus, the springs  136  can be held by the force imparted on the legs  132  by press-fitting the narrower spring rings onto a desired location on the legs  132 . Alternatively and/or additionally, the almost ninety degree bend at the legs-bridge intersection forms a stop preventing further upward movement of the distal ends of each spring  136 . Of course, the upper ring(s) can be fastened to the staple  130  by any measure, such as welding, crimping, etc. 
     Like the embodiment of  FIG. 12 , the distal end of the springs  136  in  FIG. 13  is formed by a relatively circular coil lying in the same plane as the interior cavity of the C-beam and having an outer diameter just slightly less than the interior diameter of the C-shaped cavity of the compressing portion  134 . Thus, the ends of the C-shape can be used to retain the distal end of the spring  136  within the cavity. The coils can be welded to the C-beam, for example. Of course, other fastening measures and coil configurations can be used to secure the distal ends of the springs  136  to the compressing portion  134 . 
     It is the springs  136  that provide the load-bearing force when tissue is compressed within the central region  137  of the staple  130 . Like the previous embodiments, the OTC device  133  can be shaped with variations in cross-section and other spatial characteristics and can be formed with a variety of material compositions. Any portions of the springs  136  or the compressing portion  134  can be varied. In particular, the spring  136  can be any shape or material so long as it delivers the pre-set compressive force to the tissue through the compressing portion  134  and as long as it allows for absorption of forces greater than this pre-set force. As described above, variation of any attribute of the OTC device  133  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue in the central region  137 . 
     The spring  136  shown in  FIG. 12  floats between the legs  132  and does not touch either leg  132 . In contrast, the springs  135  of  FIG. 13  wrap around the legs throughout the entire length. This orientation presents the possibility of resistance (i.e., friction) imparted upon the springs  136  by the legs  132  when the springs  136  are compressed. This resistance may be desirable depending upon the desired OTC device compression coefficient. If resistance is to be reduced, then sleeves  138  can be inserted onto the legs  132  such that they “lubricate” or reduce resistance of spring compression. These sleeves  138  can be made of polytetrafluoroethylene (PTFE), for example. 
       FIG. 14  illustrates a thirteenth exemplary embodiment of the OTC staple  140  according to the invention. This variation is similar to the embodiments of  FIGS. 12 and 13 . The OTC device  143  is, as above, a separate part from the bridge  141  and legs  142  of the staple  140  and the compressing portion  144  is a C-beam having non-illustrated ports that permit passage of a respective one of the legs  142  therethrough (in the view of  FIG. 14 , the ports are blocked from view by the C-beam). Each port has a shape substantially corresponding to the cross-sectional shape of the upper portion of the legs  142  but is slightly larger. The legs  142  pass through each port to form the OTC device  143 . In this configuration, movement of the OTC device  143  out of the bridge-legs plane is substantially prevented. 
     The C-beam shape has the same benefits as described in the eleventh embodiment of  FIG. 12 . Like that embodiment, the C-shape is not required; the compressing portion  144  can be a rectangular plate, an I-beam, an L-beam, or any other desired shape. 
     The compression device  146  can take any form. The exemplary embodiment of  FIG. 14  is a pair of compression springs  146 . Like the single spring  136  shown in  FIG. 12 , the compression springs  146  of this embodiment float between the legs  142  and do not touch either leg  142 . Connection of these springs  146  to the staple  140 , for example, at the bridge  141 , can occur by any fastening measure. The illustrated exemplary proximal connection method is a second C-beam disposed against the bridge  141  and connected thereto by any fastening measure, such as spot welds  148 , for example. With such a connection configuration, each of the springs  146  can be formed with a relatively circular coil lying in the same plane as the interior cavity of each C-beam and having an outer diameter just slightly less than the interior diameter of the respective C-shaped cavity of the compressing portion  144 . Thus, the ends of the C-shape can be used to retain the distal end of the spring  146  within the cavity. These end coils can be press-fit or slid into the C-beam cavity for connection thereto. Alternatively and/or additionally, these lower and upper loops can be fastened to the beams by welding, crimping, etc. The respective interior cavities of the two C-beams can be of different or of equal size. 
     It is the springs  146  that provide the load-bearing force when tissue is compressed within the central region  147  of the staple  140 . Like the previous embodiments, the OTC device  143  can be shaped with variations in cross-section, winding, and other spatial characteristics and can be formed with a variety of material compositions. Any portions of the springs  146  or the compressing portion  144  can be varied. In particular, the spring  146  can be any shape or winding or of any material so long as it delivers the pre-set compressive force to the tissue through the compressing portion  144  and as long as it allows for absorption of forces greater than this pre-set force. As described above, variation of any attribute of the OTC device  143  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue in the central region  147 . 
       FIG. 15  illustrates a fourteenth exemplary embodiment of the OTC staple  150  according to the invention. The OTC device  153  is, as above, a separate part from the bridge  151  and legs  152  of the staple  150 . Here, however, this variation differs from the previous embodiments because the OTC device  153  is a cushion made of a compressible material. Examples of such material include, but are not limited to, closed cell polyethylene foam, expanded polytetrafluoroethylene (PTFE), silicone rubber, silicone rubber foam, urethane, and electro-spun thermoplastic elastomers. This cushion  153  defines two channels  154  for receiving therethrough a respective one of the legs  152 . Because the staple legs  152  taper inwards slightly in a direction from the intermediate portion  155  of the staple  150  to the ends of the bridge  151  (although this taper is not a requirement), the cross-sectional area of the channels  154  are larger than the cross-section of a portion of the legs  152  disposed inside the channels  154 . By passing the legs  152  through each channel  154 , the OTC device  153  is formed. 
     It is this pillow  153  that provides the load-bearing force when tissue is compressed within the central region  157  of the staple  150 . Like the previous embodiments, the OTC device  153  can be shaped with variations in cross-section and other spatial characteristics and can be formed with a variety of material compositions. The exemplary embodiment illustrated in  FIG. 15  is a pillow having a racetrack cross-sectional shape in the transverse direction. However, the pillow can be circular, ovular, rectangular, and polygonal in its outer transverse shape. 
     Any portion of the pillow  153  can be varied so long as it delivers the pre-set compressive force to the tissue at the distal end of the pillow  153  and as long as it allows for absorption of forces greater than this pre-set force. As described above, variation of any attribute of the OTC device  153  allows for adjustment of the compressive and reactive force constants thereof on the compressed tissue in the central region  157 . 
       FIG. 16  illustrates a fifteenth exemplary embodiment of the OTC staple  160  according to the invention. This variation is different from the previous embodiments. The OTC device  163  is, as above, a separate part from the bridge  161  and legs  162  of the staple  160 . The OTC device is a plate  163  made of a semi-compressible material having properties that will be described in detail below. Examples of such a material include, but are not limited to, polyurethane and silicone rubber. The plate  163  defines two channels  164  for receiving therethrough a respective one of the legs  162 . Because the legs  162  taper inwards slightly in the bridge-legs plane in a direction from the intermediate portion  165  of the staple  160  to the ends of the bridge  161  (although this taper is not a requirement), the cross-sectional area of each of the channels  164  in the bridge-legs plane is larger than the cross-section of the legs  162  that are to be disposed inside the channels  164 . This larger area is defined by a hole that is longer in the bridge-legs plane than in the plane orthogonal thereto along the axis of the leg  162 . In the exemplary embodiment shown in  FIG. 16 , the cross-sectional shape of the channels  164  are ovular or racetrack shaped. By passing the legs  162  through each channel  164 , the OTC device  163  is formed. 
     It is noted that the staple  160  shown in  FIG. 16  is different from the prior art staple of  FIG. 1 . Specifically, the connecting portion  166  of the legs  162  tapers in width outwardly in the direction beginning from the intermediate portion towards the bridge  161  in a plane that is orthogonal to the bridge-legs plane. Because the channels  164  have a fixed width in the plane of the widening (which plane is orthogonal to the bridge-legs plane), and due to the fact that the fixed width is close in size to the lower-most portion of the connecting portion  166  (nearest to the intermediate portion  165 ), the plate  163  will not be able to move upwards towards the bridge  161  unless the material of the plate  163  is semi-compressible. Knowledge about the material&#39;s ability to compress and the resistance it provides to upward movement as the plate  163  progresses upward along the outwards taper of the leg widening can be used to set or adjust the compressive and reactive force constants thereof on the compressed tissue in the central region  167 . Any portion of the plate  163  and of the upper leg taper can be varied so long as the OTC system (plate  163  and taper of the legs  162 ) delivers the pre-set compressive force to the tissue at the distal end of the plate  163  and as long as it allows for absorption of forces greater than this pre-set force. 
     The OTC device of this embodiment can be shaped with variations in cross-section, taper, and other spatial characteristics and can be formed with a variety of material compositions. The exemplary embodiment illustrated in  FIG. 16  is a plate  163  having a racetrack cross-sectional shape in the transverse direction. However, the pillow can be circular, ovular, rectangular, and polygonal in its outer transverse shape, for example. 
     The OTC staple according to the invention is applied in the same manner as a conventional staple, that is:
         the staple is loaded into a staple cartridge;   material to be stapled with the staple is placed between the staple cartridge and an anvil; and   the anvil and staple are brought together to press the lower portion of the legs against the anvil and bend the lower portions inward to capture the material in the central region and compress it between the bent portions and the compressing portion of the staple.       

     Because the material to be stapled has a length less than the distance between the bent lower portions and the bridge, the captured material partially compresses the OTC device inside the staple to, thereby, effect the optimal tissue compression feature. When the staple and material are released from the staple cartridge and anvil, the OTC device is imparting a pre-set compressive force against the compressed material. Significantly, the OTC device is able to move while the material is going through its compression and expansion cycle(s) until it finally reaches a steady state size. Even after reaching the steady state, the OTC device imparts the desired compressive force (within an acceptable minimum range) so that the material is not permanently damaged due to overcompression. 
     For example, if the material is human tissue, when tissue is stapled, liquid is forced out of the tissue. During the desiccation period, the tissue compresses further and further. The OTC device compensates by enlarging to follow the tissue compression. At some point in time, the tissue begins to swell (due to the puncturing and compressing forces imparted thereon). During the swelling period, the OTC device compensates by reducing to follow the tissue swelling. 
     The foregoing description and accompanying drawings illustrate the principles, preferred embodiments and modes of operation of the invention. However, the invention should not be construed as being limited to the particular embodiments discussed above. Additional variations of the embodiments discussed above will be appreciated by those skilled in the art. 
     Therefore, the above-described embodiments should be regarded as illustrative rather than restrictive. Accordingly, it should be appreciated that variations to those embodiments can be made by those skilled in the art without departing from the scope of the invention as defined by the following claims.