US20050096660A1 - Compression bone staple, apparatus and method - Google Patents

Abstract

A method and apparatus for interosseous bone fixation uses a compression staple, generally U-shaped, having a pair of legs with sharp front ends and proximal ends interconnect by a bridge portion that is resilient and bowed, the staple having an initial configuration and capable of a tensioned configuration by spreading apart the legs by a certain amount causing the curvature of the bowed bridge to lessen and the legs urged towards each other with certain compressive spring force. A staple applicator supports and guides the staple and positions the tensioned staple with its pointed ends forward, adjacent an ejection port at the front of the applicator. A powered strike member is mounted for longitudinal movement and has a front end that will strike the rear of the tensioned staple with percussive force and eject it in tensioned configuration from the applicator.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to devices and techniques for securing bone segments across a fracture site, and more particularly relates to a bone stapling method and apparatus for achieving compression between segments.
• 2. Description of the Prior Art
• In treating a bone fracture it is common practice to fasten one bone segment to the other so as to stabilize and immobilize them for the duration of the bone consolidation process. Thus there is the technique of internal fixation or direct mechanical fastening of the bone segments.
• Traditionally, fixation has been accomplished by variety of apparatus and techniques, the more common involving the use of metallic fastening devices such as screws, connector plates (secured to the bone by screws), pins and clips. These methods invariably involve the drilling of screw holes in the bone and the use of related equipment such as drill hole templates.
• Conventional U-shaped clips have also been used, the clip legs being installed one each in holes in the opposing bone segments. The rigid structure of such clips, like the other fixation devices mentioned above, provide rigid immobilization of the fracture zone. Such devices also served to maintain the distance between segments, which was found however, among other things, to hinder compression induced by contractions of skeletal muscles in some cases, and prevent the establishment of compressive force between the bone segments which is favorable to bone consolidation or knitting. In this regard the concept of creating dynamic compressive force across an osteotomy or bone fracture site has become well recognized as a technique to promote primary bone healing, i.e. consolidation that is faster and of better quality.
• Thus there has evolved a number of fastening devices such as clips and the like, designed to deliver compression. Accordingly in U.S. Pat. No. 3,939,294 there is provided a clasp or clip of spring material having a pair of spaced-apart, inwardly inclined legs connected by a Z-shaped upper portion. Sloped holes are drilled in adjoining bone segments and tools are used to manipulate and install one leg, and then the other leg is pulled toward the other hole, spreading the Z-shaped elastic portion, and then inserted in the other hole. Unfortunately this method requires the drilling of specially sloped holes, involves multiple steps and is time-consuming, and like the conventional rigid fastening techniques, requires relatively large surgical opening. Also, the manual installation of the clip using hemostats and the like is difficult, requires meticulous skill and handling.
• In U.S. Pat. No. 4,838,254 the legs of a pair of metallic clips are inserted in pairs of specially angled bores in respective opposing bone segments. The exposed tops of the two installed clips then serve as fastening heads for a spring that is connected between the clips.
• In U.S. Pat. No. 4,841,960 the disclosed “compression” clip is essentially a clip with opposing legs that are installed in pre-drilled holes and features a crimpable web that joins the top ends of the legs. A crimping tool is used to crimp the web in an effort to set up compression between the embedded legs.
• U.S. Pat. No. 4,852,558 also requires manual installation of separate legs in pre-drilled holes, the tops of the install legs then being interconnected with a ratchet mechanism which must be operated to draw the legs together. This design appears inherently limited regarding adjustability and maintenance of constant pressure. In U.S. Pat. No. 5,660,188 the two legs of a clip must also be installed in pre-drilled holes. The clip has a bridge of two side-by-side crimpable elements, and the jaws of a crimping tool must be used on the embedded clip to deformingly spread apart these elements, causing the legs to draw to each other. The foregoing techniques involving crimpable clips all appear to be imprecise in setting up suitable compressive forces, require hole drilling and related problems, and do not lend themselves to minimizing the size of the surgical opening.
• In view of the limitations of the afore-mentioned methods, stapling has been looked to as a potentially quick and effective way for fastening bone segments, and as a way to produce compression. Thus in U.S. Pat. Nos. 5,053,038 and 5,662,655 “compression” staples are applied to the bone by a powered stapler. These staples have legs shaped with beveled ends and/or have divergent legs that will be forced apart from each other during implantation, which flexes springy upper parts of the legs thereby tending to set up compression. Unfortunately there is concern for trauma to the bone due to driving of the compound-shaped legs into the bone mass, and there is little apparent precision in establishing the desired compressive forces.
• In view of the foregoing it is a general object of the present invention to provide an improved method and for interosseous fastening.
• A more particular object is to provide quick and simple, yet effective method for fastening bone segments with compressive force between opposing bone ends.
• Another object to provide such a method that minimizes the size of the required surgical opening and associated trauma.
• A further object to provide a method of bone stapling that minimizes trauma to the bone tissue during implantation of the staple legs.
• Yet another object is to provide a method for stapling that maximizes the capability of establishing a dynamic compression level that is optimal for enhanced osseous healing.
• A still further object is to provide simple, effective bone fixation technique that is relatively easy to learn and practice.
• Another object is to provide for compression fixation in applications where other techniques would not work or would not deliver compression. For example, conventional fastening techniques for handling a “Jones” fracture, i.e. one that is transverse to the longitudinal extent of the bone segment, is difficult to address using conventional fastening techniques, however the present invention is particularly suitable to provide fastening for such fractures.
• Still another object is to provide stapling apparatus and method in which there is enhanced selection capability regarding the level of the compressive forces to be imparted.
• There are a number of advantages in exterior bone fixation techniques, where surgical incisions are not required and fasteners are applied through the skin; and thus it is yet another object of the invention to provide a bone stapling method that lends itself well to exterior bone fixation.
• These and other objects of the present invention are achievable by way of the present invention of a bone stapling method and apparatus that uses a generally U-shaped staple having pair of spaced apart legs with sharp free ends and proximal ends interconnected by bridge that has at least one resilient curved portion, whereby spreading apart of the parallel legs lessens the curvature of the curved portions which brings the staple to a tensioned configuration in which one leg is resiliently urged towards the other. In a preferred embodiment it is seen that the bridge portion comprises a single bowed spring element, the curvature of which lies in a plane normal to the axes of the staple legs.
• The novel fastening method involves first positioning the fractured ends of a first and a second bone segment in proximate, face-to-face relationship. The next step involves spreading apart the staple legs by a certain amount and holding the staple in the resultant tensioned configuration. The extent to which the staple legs are separated can be varied in one preferred embodiment of the invention, the induced compressive forces between the legs being proportional to the amount of displacement of the legs as the bowed portion is moved through range of motion in which elastic behavior is exhibited. In this regard it should be evident that herein lies one of the advantages of the present invention, i.e. the capability of selecting the optimal compressive force for an application by spreading apart the staple legs by a predetermined amount.
• Next, as the staple is held in its tensioned configuration, it is positioned with it sharp ends forward and aligned respectively with surfaces of one bone segments and the other. Finally the positioned staple, while maintained in its tensioned configuration, is driven into the bone by percussive force, such quick application being provided by a conventional air-powered striker of a stapler according to the present invention, or by a manually stuck staple applicator according to the invention. The embedded staple legs will cause the opposing bone faces to be pressed into each other with a predetermined amount of force.
• Such stapling method lends itself advantageously to a staple with a relatively narrow profile, wherein apparatus according to the present invention include a staple applicator having within its housing means for supporting the staple and guiding its movement with legs pointed ends forwardly disposed, and adapted to receive the staple in its initial untensioned configuration engaging its legs and spreading them apart by certain amount and holding the staple in its tensioned configuration adjacent the front end of the housing, for ejection therefrom. One embodiment, of several, uses opposing first and second grooves for engaging the staple legs and means for adjustably moving one groove from the other. Another embodiment employs grooves that diverge to spread the staple legs as a staple is advanced there-along. Ejection means mounted for longitudinal movement in the housing has a front end adapted to strike the rear of the tensioned staple with percussive force which is provided by air power or electrical power in preferred embodiments.
• The invention also includes a staple applicator that is adapted for being manually driven.
• Another related bone stapling method for compressively securing adjoining bone segments uses a resilient metallic staple that has legs with an initial convergent configuration with respect to each other, and the legs are resiliently extendible into parallel relationship, in which configuration a predetermined amount of spring force will urge the legs towards their initial convergent orientation. This method includes holding the normally convergent staple in its legs-parallel configuration, positioning the so-tensioned staple with its sharp ends aligned respectively with adjacent bone surfaces; and then driving and embedding the legs of the tensioned staple in the bone segments and releasing the embedded staple, whereby the bone segments are joined, and opposing surfaces of the bone segments are caused to be pressed into engagement with each other with a certain amount of compressive force.
• An applicator or tool for such a staple includes staple-engaging means on the front end of the applicator body. Opposing jaws support the staple in a pointed-ends forward position against lateral and rearward movement, and engage inside surfaces of the convergent legs, the jaws being adapted for adjustable movement apart to cause the legs to rotate to a generally parallel orientation. Thus supported on the front end of the tool, the staple can be aligned with the bone segments, and the rear end of the tool stuck with a percussive force to cause the staple legs to be embedded into the bone segments.
• Another applicator according to the present invention has a trigger-controlled air-powered staple-driving mechanism, and has a staple feeding mechanism including ramp means that is shaped to receive and support a staple in its initial configuration on one end of said ramp means, the configuration of the ramp means gradually changing to a shape that will hold the staple with its legs generally parallel with each other. Thus the staple can be slidably pushed along the ramp means in a lateral direction, i.e. normal to the plane in which the staple legs and bridge portion lie, to bring it to a terminal position along the ramp means, in which position the rear of the tensioned staple can be struck by the front end of a powered striker.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is perspective view of a preferred embodiment of a compression staple according to the present invention;
• FIG. 2 is top plan view of the embodiment of the staple ofFIG. 1;
• FIG. 3 is a rear end elevational view of the staple ofFIG. 1;
• FIG. 4 is a perspective view of variant of a staple according to the present invention;
• FIG. 5 is an elevational view of staple applicator according to the present invention, with parts broken away for the sake of clarity;
• FIG. 6 is a partial, perspective enlarged view of the front end of the staple applicator ofFIG. 5;
• FIG. 7 is a sectional view taken long the line7-7 ofFIG. 6;
• FIG. 8 is sectional view taken long the line8-8 ofFIG. 6;
• FIG. 9 is an enlarged, partial perspective view of the front portion of a variant of a staple applicator according to the present invention;
• FIG. 10 is an enlarged, partial perspective view of the front portion of another variant of a staple applicator according to the present invention;
• FIG. 11 is a top plan view of a manually powered stapler according to the present invention;
• FIG. 12 is a partial, enlarged perspective view of the front portion of the staple applicator ofFIG. 11;
• FIG. 13 is a sectional view taken along the line13-13 ofFIG. 12;
• FIG. 14 is a perspective view of another variant of a compressive staple according to the present invention, wherein the staple legs have a convergent orientation with respect to each other;
• FIG. 15 is a side elevational view of the staple ofFIG. 14;
• FIG. 16 is a top plan view of a staple applicator according to the present invention;
• FIG. 17 is an enlarged, partial perspective view of the front end of the applicator ofFIG. 16;
• FIG. 18 is an enlarged partial, side elevational, partially sectional view illustrating the mounting of a staple on the front end of the staple applicator ofFIG. 16;
• FIG. 19 is a view similar toFIG. 18 showing a staple supported with legs parallel;
• FIG. 20 is a perspective view of a convergent-legged staple that is adapted to be fed to a powered staple applicator;
• FIG. 21 is a rear elevational view of the staple ofFIG. 20;
• FIG. 22 is a side elevational view of another powered applicator according to the invention;
• FIG. 23 is a perspective illustration showing means for feeding staples to the staple-driving means of the powered staple applicator shown inFIG. 22;
• FIG. 24 is a partial, enlarged, partial sectional side view of staple-delivering ramp member of the applicator shown inFIG. 22;
• FIG. 25 is a schematic illustration of the staple-striking region of the staple feeding means ofFIG. 23;
• FIG. 26 is a perspective view of another variant of another compression staple similar to the staple ofFIG. 1, and adapted for use with a staple-feeding magazine or cartridge;
• FIG. 27 is a front end elevational view of the staple ofFIG. 26; and
• FIG. 28 is a partial sectional perspective view, with parts broken away for the sake of clarity, illustrating a magazine or cartridge for feeding the staple ofFIG. 26 to a powered staple applicator.
DETAILED DESCRIPTION OF THE INVENTION
• Referring now the drawings,FIGS. 1-3 show that a preferred embodiment of a compression staple11 according to the present invention has a pair oflegs13 with sharp front ends15 and abridge17 that interconnects the rear end portions oflegs13. Staple11 is fabricated of a surgical grade, bio-compatible metal, such as stainless steel, titanium alloy or other suitable alloy.Bridge17 functions not only to holdlegs13 in approximate parallel relationship, but is selected to act as a spring by the flexing of its bow when the legs are spread apart as illustrated by the broken line image ofFIGS. 2 and 3. This imparts an inward reacting force between the legs proportional to the degree of their displacement. It will be appreciated that the dimensions, gauge and curvature ofbridge17 are selected such that it can be flexed to a tensioned state that will deliver the compression requirements of the bone fixation to which staple11 is to be applied.
• It is preferred that the opposing inside surfaces oflegs13 are provided with serrations orbarbs19. In this regard it is noted that, inasmuch as the insides oflegs13 will be pressed against bone mass when they are embedded in a manner to be described, the size of such serrations or barbs can be advantageously minimized, which minimizes trauma to the bone tissue during their implantation.
• It will be evident that there can be several variations of compression staples according to the principles of the invention. For example, staple legs can have various cross sectional configurations, including diamond-shaped, square, triangular and rectangular.FIG. 4 shows avariant23 of a staple according to the present invention, havinglegs25. It is formed from metal rod having suitable strength and spring properties. It is also contemplated under the invention that the curvature of the bridge can take other forms than the single bow shown, and would include, among others a generally V-shape and a shape with double 90 degree bends.
• FIG. 5 shows an air-poweredstaple applicator29 for applying staple11, and it includesmain body31, a conventionalair piston assembly33 withinbody31,air supply line35 and a pistol grip and triggerassembly37 for holding the stapler and for controlling the air-powered operation of thestaple head41, to be described hereinafter.
• AsFIG. 6 illustrates, thestaple head41 features anadjustable staple mount43 that includeslower head45 which is a forward extension ofbody31, andupper head47. A pair ofparallel guide rods51, affixed tolower head45 and extending upwardly therefrom, slidably engage twin bores53 in theupper head47 so as to guide the upper head in vertical motion relative to thelower head45. A screw jack assembly drives the upper head and includes thrustscrew55 that engages the threaded bore57 inlower head45.FIG. 7 best illustrates the screw jack assembly and shows turnknob59 that has a socket for receiving a tool such as an Allen wrench for rotating theknob59.FIGS. 6 and 7 also show alongitudinally extending groove65 on thelower head45 and a corresponding parallel groove63 on the movableupper head47, these grooves being shaped to cradle the opposing sides ofstaple legs13, and the knob can be operated to set the spacing between grooves to allow staple11, in its initial un-tensioned configuration, to be mounted thereon as illustrated.
• In a preferred embodiment, vertically extending gradations are provided at67 on a forward surface ofbody31, adjacent the movable rear end ofupper head45, so as to gauge the displacement of the staple legs when the invention is operated in a manner to be described below.
• AsFIGS. 6 and 7 and8 also show,staple applicator29 includes mechanism for driving a staple forwardly from thestaple head41, and includes longitudinally extendingstriker member69 that is slidably mounted togrooves71 and73 for longitudinal movement, and the rear portion (not shown), is connected to the air piston assembly, and spring means (not shown) will hold the striker in an initial rearward position as illustrated inFIG. 6.Striker member69 hasfront surface75 that is adapted, as best shown inFIG. 7, to impact the rear legs of thestaple bridge17 when thestriker member69 is propelled to its forward position shown by the phantom lines inFIG. 6.
• In the operation ofstaple applicator29 for osteosynthesis, a staple11 is mounted to thestaple mount43 which is operated to bring the staple to the desired tensioned configuration. Then bone segments are brought together by manual or mechanical manipulation as close as possible and aligned with each other. Thestapler head41 can then be positioned with its legs straddling the fracture line, and sharp ends15 adjacent the surfaces of the bone segments. The stapler trigger can then be operated to cause the striker to drive the legs of the tensioned staple into the bone segments.
• There is a variant of a staple applicator according to the invention that is identical to the embodiment ofFIGS. 6 and 7, except that it has a striker member69ais designed to engage the rear ends ofstaple legs13 instead of the rear edge of thestaple bridge17. Thus the sectional view ofFIG. 9 shows ends79 and80 that are adapted to strike respectively the upper and lower rear ends ofstaple legs13, of a staple11 supported in tensioned configuration. It is contemplated under the invention that strikers like striker69a, with differently spaced ends79 and80 can be provided so that different sized staples can be accommodated.
• FIG. 10 shows theforward portion81 of another variant of a power stapler applicator according to the present invention, having amain body82, anupper staple guide83 andlower staple guide85. Opposing forwardportions87 of the guides are separated by a distance allowing it to hold staple11 in tensioned configuration, and therearward portions89 will hold the staple in its initial configuration. The open-sided portions91 allow a staple to be loaded by hand unto the staple guides. When the staple is pushed forwardly by hand fromportion89 toportion87, thedivergent portions93 will cause the spreading apart of the staple legs, and thus a tensioned staple is positioned for ejection.
• Astriker member95 has upper andlower edges97 and99 slidablyengagedin slots101 and103 so as to mount the striker member for longitudinal movement. The striker front ends105 and107 will align with and abut the rear ends of a tensioned staple.
• FIGS. 11, 12 and13 show avariant113 of the invention, whereby percussive force is delivered by hand using a suitable mallet. Here thebody115 has arear portion117 designed for being struck by a mallet, andstaple holder119 at its front end.FIGS. 12 and 13 show how theholder119 includeslower portion121 that has staple leg-receivinggroove129, and an adjustableupper part135 withgroove137.FIG. 12 best shows how a dove-tail portion141 ofpart135 fits in a complementary slot for guiding vertical movement ofpart135. Front surfaces145 and147 respectively ofparts121 and135 are adapted to abut the rear ends of a staple mounted ingrooves137 and129. Ascrew153 for driving thepart135 has threads157 that engage a threaded bore159 in themovable part135, and theknob163 can be engaged by a suitable tool to rotate thescrew153.
• In usingtool113 the sharp ends of a tensioned staple11 can advantageously be precisely positioned on the target spots on the bone segments, then thetool end117 struck with a mallet to implant the staple.
• Referring now toFIGS. 14 and 15 there is shown inFIG. 14 anothercompressive staple161 according to the invention that is fabricated of a suitable resilient metal, and featureslegs163 and165 that converge with respect to each other, and interconnect by abridge167.Staple161 can also be made of a suitable resilient non-metallic bio-absorbable material.
• FIG. 15 best shows howlegs163 and165 each converge at a pre-selected angle Φ, with respect to parallel positions that the legs can be resiliently urged in a manner to be described hereinafter. It should be apparent that the material properties of the selected resilient material, the degree of convergence, and the dimensions and form of the staple will be selected by those with ordinary skill in the pertinent art so as to establish a certain force by which the parallel legs are urged to their convergent positions.
• FIG. 16 shows one preferred embodiment of a bone-staple applicator171 having amain body173 with arear end175 adapted for being impacted by a force delivering instrument like a mallet. Thefront end177 is designed to mount a staple161 in its initial configuration and then move it to, and hold it in, a configuration where its legs are parallel. Thus it is seen inFIG. 17 thatfront end177 has anupper jaw181 that can be adjustably spaced from to alower jaw183 using drive-screw mechanism similar to that used for the screw-drivenspreadable parts135 and121 previously described above and shown inFIGS. 12 and 13.FIG. 17 shows how theupper jaw181, andlower jaw183 are shaped to mount astaple161, theslots187 and189 in the respective jaws being sized to receive thestaple bridge167. A recessedportion191 in the top ofthee jaw181 is for supporting and stabilizing rearward portions of the upperstaple leg163, and there is a similarly recessed portion on the under-surface of the lower jaw183 (not shown) for supporting therearward part196 of lowerstaple leg165. The recessedportion191 has ashelf193 for engaging lower surfaces ofleg163, and opposingedges195 can hold the staple against lateral movement while theledge197 is adapted to abut the rear edge of the staple leg.
• FIG. 18 best shows how anuntensioned staple161 is first mounted within the grasp of the opposing recessed portions of thejaws181 and183, and it is noted how surfaces193 and194 engageinner surfaces211 and213 of opposinglegs163 and165. It should be appreciated how thescrew mechanism217 can be operated to move apart the opposing jaws, causing the opposing legs to be pushed into parallel relationship, as illustrated inFIG. 19. When astaple161 is thusly mounted on theapplicator tool171, it can be used much the same as the previously describeddevice113, to apply atensioned staple161 to adjoining bone segments. Note that the jaw surfaces193 and194 can be appropriately sloped to ensure that the legs will be pushed into parallelism.
• FIGS. 20 and 21 show another embodiment of a compression staple according to the present invention, i.e. the staple261 which is particularly adapted for application by a powered applicator, for example an electrically powered or an air-powered staple applicator such asapplicator271 shown inFIG. 22, to be described. Like the previously describedstaple161, thestaple261 is fabricated of a suitable resilient metal using conventional metal-working techniques. Thestaple legs263 and265 extend from thebridge portion267 and converge at a predetermined angle. It is noted howlegs263 and265 are wider than thebridge portion267. The inside surfaces of the staple bridge and legs are adapted to slidably engage staple-feeding ramp structure, to be described. Furthermore,FIG. 21 best shows how this staple structure provides to one side of thebridge267, opposing insidesurfaces270 and274 respectively oflegs263 and265, which can be advantageously engaged for slidable forward movement of the staple along parallel guide surfaces in the poweredstaple applicator271, in a manner to be described.
• The trigger-controlledapplicator271, shown inFIG. 22, except for its forward end, is similar to the above-describedapplicator29, and includes apiston assembly275.FIG. 23 illustrates how at the forward end of theapplicator271, there is mounted astaple feeder273 designed to supply and position staples for engagement by thefront end279 of astriker281 that is connected to thepiston assembly275.
• FIG. 23 shows that thefeeder273 includes ahousing285 that is attached to a sidewall of the applicator and which supports aramp member287 that has adistal end289 that is shaped to receivestaples261. Thewalls291,292 and293 are shaped so as to be slidably embraced by a number ofstaples261 in their relaxed, legs-convergent configurations.FIG. 24 also illustrates theramp member287 and shows how theramp walls291 and292 vary from a convergent orientation at one ramp end to a generally parallel one at theopposite ramp end294.FIG. 23 also illustrates that within thefeeder housing285 there is a spring-poweredpusher295, connected to a suitable conventional spring (not shown) for urging thepusher295 against the rear side edges of a staple261 mounted on theramp member287. Thus it can be appreciated how astaple261, or several side-by-side staples261, can be slidably pushed towards theend294 of the ramp member.
• The enlarged view ofFIG. 25 shows how the innermost end of theramp member287 has anend299 that is spaced from a guidingsurface301 ofapplicator wall304.Surfaces301 and the opposing upper andlower surfaces303 and305 form a channel asFIG. 24 shows, for receiving thestriker281.FIG. 25 shows in broken lines atensioned staple261 in position for being driven by thestriker281. Note that thebridge member267 is spaced within the above-mentioned channel, clear of the end of theramp member287, the staple being supported by virtue of the staple leg surfaces270 and274 (FIG. 21) engaging the ramp member. Thus the strikerfront end279 is aligned with the rear end ofstaple bridge portion267.
• In operation ofapplicator271 it is supported with its front end in close proximity to the relevant bone segments, and with the pointed ends of the staple appropriately aligned therewith. Pulling the trigger will cause thestriker end279 to impact the staple bridge and propel the staple forwardly as the staple legs are held generally parallel by sliding engagement with the generally parallel surfaces of theramp member287 during ejection.
• The striker will have a stroke sufficient to cause the legs, in their parallel configuration, to be embedded in the bone tissue. The striker will return to its initial position rearward of the ramp member. Then spring force will cause another staple to be positioned in the ejection channel.
• AlthoughFIGS. 22 and 23 show thefeeder273 connected adjacent thefront end260 of the applicator, it should be appreciated that in some cases it is desirable that thefeeder273 attaches to theapplicator271 at a location spaced a greater distance to the rear of the front260. In such cases theramp walls291 and292 in the region ofwall301 are elongated forwardly as necessary to provide guide surfaces for the staple, and the stroke of thestriker281 is increased accordingly.
• FIGS. 26 and 27 illustrate yet anothervariant361 of the compression staple11 described above (FIG. 1), and has generallyparallel legs363 and365 andresilient bridge367. This configuration provides opposingsurfaces370 and374, best shown inFIG. 27, that are adapted to engage parallel guide surfaces when thestaple361 is propelled from a poweredstaple applicator371; to be described. InFIG. 27 the tensioned configuration ofstaple361 in shown in broken lines.
• FIG. 28 shows afeeder373 which is constructed similarly to the above-describedfeeder273, except that theramp member387 is adapted to handle thestaple361. Thus theramp walls391 and392 provide parallel surfaces for engaginginside surfaces of the staple legs and thewall393 slidably abuts thewall393.
• The distal end of theramp387 receivesstaples361 in their untensioned condition, and thewalls391 and392 gradually diverge from each other such that at theother end395 of the ramp, astaple361 will be supported in a legs-parallel tensioned configuration. A spring-poweredpusher399 is adapted to urge a number of nestedstaples361 towards theend395 of the ramp.
• Theramp end395 is spaced a predetermined distance from theguide surface401 and provides surfaces that engage the opposingsurfaces370 and374 ofstaple361. Thus the rear of a tensioned staple can be struck by thestriker397 and ejected from the applicator.
• While particular embodiments of the invention have been described, it should be understood that the invention is not limited thereto, and includes other variants and modifications that will readily occur to those persons of ordinary skill in the art, given the benefit of this disclosure. Thus it is intended that the invention be given its full scope and breath as defined in the claims which follow.

Claims (16)

1. 21. A stapling method for fastening a first bone segment to a second bone segment, said first bone segment having an end to be connected to an end of said second bone segment, said method including the steps of:

   a) positioning the end of said first bone segment in face-to-face adjacent relationship with the end of said second bone segment;

   b) providing a generally u-shaped staple having a pair of spaced apart legs with sharp free ends and other ends interconnected by a bridge portion, and said staple having an initial untensioned configuration in which said legs converge with respect to each other;

   c) moving said staple from its initial configuration to a tensioned configuration in which said legs are held generally parallel to each other and in which said legs are resiliently urged towards their initial configurations;

   d) holding and positioning said tensioned staple with each of the sharp ends of said legs aligned respectively with a spot on the surface of said first and second bone segments; and

   e) driving and embedding the legs of said tensioned staple into said bone segments and releasing said staple, whereby the opposing faces of the bone segments are caused to be pressed into engagement with a predetermined amount of compressive force.
2. 22. A method as defined inclaim 21 wherein the step of driving and embedding of said staple legs is effected by percussion.
3. 23. A method as defined inclaim 21 wherein said step of moving said staple to its tensioned configuration includes slidably engaging opposing inner surfaces of the legs and bridge portions of said staple in its untensioned configuration with surfaces of a ramp and then moving said staple along said ramp in a direction normal to the plane in which lie said legs and bridge portion, so that said legs slidably follow surfaces of said ramp that are configured to urge said legs into parallel relationship.
4. 24. A method as defined inclaim 21 wherein said step of driving and embedding said staple legs includes slidably moving said along parallel surfaces.
5. 25. A compression staple for fastening a first bone segment to a second bone segment, said staple comprised of a resilient material and having a generally U-shaped configuration, and comprising:

   a) first and second spaced-apart longitudinally extending legs with sharp free ends and proximal ends;

   b) a bridge portion interconnecting the proximal ends of said legs; and

   wherein said legs have a convergent orientation, one to the other, and said legs are adapted to be resiliently held in a parallel orientation wherein said legs are urged towards their initial convergent orientation with a predetermined force.
6. 26. A staple as defined inclaim 25 wherein said legs are wider than said bridge portion.
7. 27. A staple as defined inclaim 26 wherein said bridge portion lies to one side of said legs and the other sides of said legs have opposing generally flat surfaces.
8. 28. A bone staple applicator for a generally U-shaped staple having a first and a second spaced apart legs with sharp free ends and proximal ends interconnected by a bridge portion, and an initial configuration where said legs are convergently oriented, and said staple capable of a tensioned configuration in which said legs are held in parallel relationship, said staple applicator including:

   a) an elongate body with a front end and a rear end, and including:

   i) means on said body front end for supporting said staple against rearward and lateral movement with the sharp ends of its legs forwardly disposed, and adapted for engaging opposing portions said legs and moving said legs into parallel relationship.
9. 29. A bone staple applicator as defined inclaim 28 wherein said tool body has a handle portion, and said rear end is adapted for being struck a percussive blow.
10. 30. A bone staple applicator for a generally U-shaped staple having a first and a second spaced-apart legs with sharp free ends and proximal ends interconnected by a bridge portion, and wherein said legs have an initial convergent orientation one to the other, and said staple capable of a tensioned configuration in which said legs are held in parallel relationship, said parallel legs urged towards their initial convergent orientation by certain spring force; said staple applicator including:

    a) a longitudinally extending body with a front end and a rear end, and including:

    i) means on said body front end for supporting said staple in its tensioned configuration with the sharp ends of its legs forwardly disposed, and adapted for engaging opposing inside surfaces of said legs and for guiding longitudinal forward movement of said tensioned staple;

    ii) means for moving said staple from its initial orientation to its tensioned configuration, and for delivering said staple to said staple supporting means; and

    iii) means mounted to said body for striking the rear end of said tensioned staple with percussive force for driving said tensioned staple forwardly from said staple-supporting means.
11. 31. An applicator as defined inclaim 30 wherein said striking means includes an elongate striker mounted to said body for longitudinal movement, and having a front end adapted for impacting the rearward end portion of said staple.
12. 32. An applicator as defined inclaim 30 wherein said means for supporting said staple includes opposing first and second supports adapted for engaging respectively the first and second legs of said staple, and mounted for being adjustably spread apart so as to move said legs to a parallel orientation.
13. 33. An applicator as defined inclaim 32 wherein said means for adjustably moving said supports comprises drive means, engaging said first and second supports.
14. 34. An applicator as defined inclaim 33 wherein said drive means includes drive screw mechanism.
15. 35. An applicator as defined inclaim 30 wherein said means for moving said staple and delivering said staple includes elongate ramp means adapted for slidably engaging inner surfaces of said staple legs and bridge portion, and having surfaces configured so that said legs are pushed from their divergent orientation to parallel orientation by virtue of moving said staple in a direction along said ramp in a direction normal to the plane in which said legs and bridge portion lie; and means for pushing said staple along said ramp means.
16. 36. An applicator as defined inclaim 35 including means for biasing a staple along said ramp means towards the proximal end of said ramp means.

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