Patent Publication Number: US-2022218339-A1

Title: Applicator instruments for dispensing surgical fasteners having deflectable staging assemblies

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present patent application is a continuation of U.S. patent application Ser. No. 16/267,969, filed on Feb. 5, 2019, now allowed, which is a continuation of commonly assigned U.S. patent application Ser. No. 15/299,648, filed Oct. 21, 2016, now U.S. Pat. No. 10,729,433, which is a continuation of commonly assigned U.S. patent application Ser. No. 14/522,680, filed Oct. 24, 2014, now U.S. Pat. No. 9,855,041, which is a continuation of commonly assigned U.S. patent application Ser. No. 12/464,143, filed May 12, 2009, now U.S. Pat. No. 8,894,669, and which is related to the following commonly assigned U.S. patent applications: U.S. patent application Ser. No. 12/464,151, filed May 12, 2009, now U.S. Pat. No. 8,579,920, U.S. patent application Ser. No. 12/464,165, filed May 12, 2009, now U.S. Pat. No. 8,728,098, U.S. patent application Ser. No. 12/464,177, filed May 12, 2009, now U.S. Pat. No. 8,728,099, and U.S. patent application Ser. No. 29/459,660, now U.S. Pat. No. D744,646. The disclosures of the above-identified patent applications and patents are hereby incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention generally relates to surgical fasteners, and more specifically relates to applicator instruments, systems and methods for deploying surgical fasteners. 
     Description of the Related Art 
     Hernia is a condition where a small loop of bowel or intestine protrudes through a weak place or defect within the abdominal muscle wall or groin of a patient. This condition commonly occurs in humans, particularly males. Hernias of this type may result from a congenital defect whereby the patient is born with this problem, or may be caused by straining or lifting heavy objects. Heavy lifting may be known to create a large amount of stress upon the abdominal wall and can cause a rupture or tearing at a weak point of the abdominal muscle to create the defect or opening. In any case, the patient may be left with an unsightly bulge of intestinal tissue protruding through the defect, which may result in pain, reduced lifting abilities, and in some cases, impaction of the bowel, or possibly other complications if the flow of blood is cut off to the protruding tissue. 
     A common solution to the above-described problem may be surgery. During a surgical procedure, the defect is accessed and carefully examined, either through an open incision or endoscopically through an access port such as a trocar. In either case, careful examination is required due to the network of vessels and nerves which exist in the area of a typical defect, which requires a surgeon to conduct a hernia repair with great skill and caution. Within this area can be found vascular structures such as gastric vessels, the external iliac vessels, and the inferior epigastric vessels, as well as reproductive vessels such as the vas deferens extending through the inguinal floor. 
     Once the surgeon is familiar with the anatomy of a patient, the surgeon carefully places the viscera back into the patient&#39;s abdomen through the defect. Repairing the defect can involve closure of the defect with sutures or fasteners but generally involves placing a surgical prosthetic such as a mesh patch over the open defect, and attaching the mesh patch to the abdominal wall or inguinal floor with conventional suture or with surgical fasteners. The mesh patch acts as a barrier and prevents expulsion of bowel through the defect. Suturing of the mesh patch to the inguinal floor can be well suited to open procedures but can be much more difficult and time consuming with endoscopic procedures. With the adoption of endoscopic surgery, endoscopic surgical instruments that apply surgical fasteners can be used. However, the tissue of the inguinal floor may offer special challenges to the surgeon when a needle or fastener is used to penetrate structures such as Cooper&#39;s ligament. 
     At present, there are a variety of surgical instruments and fasteners available for the surgeon to use in an endoscopic or open procedure to attach the mesh patch to the inguinal floor. One of the earliest types of endoscopic surgical instruments used is a surgical stapler. A plurality or stack of these unformed staples may be generally contained within a stapling cartridge in a serial fashion, and may be sequentially advanced or fed within the instrument by a spring mechanism. A secondary valving or feeding mechanism may be employed to separate the distal most staple from the stack, to hold the remainder of the spring loaded stack, and may be used to feed the distal most staples into the staple forming mechanism. Feeding mechanisms of this type are found in U.S. Pat. No. 5,470,010 to Rothfuss et al., and in U.S. Pat. No. 5,582,616, also to Rothfuss et al. 
     Another hernia mesh attachment instrument uses a helical wire fastener that resembles a small section of spring. Multiple helical wire fasteners may be stored serially within the 5 mm shaft, and may be corkscrewed or rotated into tissue. A load spring may be used to bias or feed the plurality of helical fasteners distally within the shaft. A protrusion extends into the shaft to possibly prevent the ejection of the stack of fasteners by the load spring and may permit passage of a rotating fastener. Instruments and fasteners of these types are found in U.S. Pat. No. 5,582,616 to Bolduc et al., U.S. Pat. No. 5,810,882 to Bolduc et al., and in U.S. Pat. No. 5,830,221 to Stein et al. 
     Whereas the above surgical instruments may be used for hernia fastening applications, they use a spring mechanism to feed a plurality of fasteners through the surgical instrument. Spring mechanisms typically use a long soft coil spring to push a stack of fasteners through a guide or track within the shaft of the surgical instrument. These types of feeding mechanisms may be generally simple and reliable, but may require an additional secondary valving mechanism or protrusion to separate and feed one fastener from the stack. 
     Other surgical fasteners may be used for hernia mesh attachment but utilize either a reloadable single shot instrument or a rotary magazine that holds a small number of fasteners. These types of surgical fastening instruments can be found in U.S. Pat. Nos. 5,203,864 and 5,290,297, both to Edward Phillips. These instruments have not gained acceptance by the surgical community, possibly due to their single shot capabilities and the large size of the rotary magazine, which can restrict such an instrument to an open procedure. 
     Whereas all the above surgical instruments may be used for hernia fastening applications, they either use a spring mechanism to feed the plurality of fasteners through the surgical instrument, or a rotary magazine in lieu of a feeding mechanism. Other types of surgical fasteners may be available, such as surgical clips, and they can utilize feeding mechanisms that do not require the use of a spring to feed the clips distally. A reciprocating feeding mechanism is described in U.S. Pat. Nos. 5,601,573; 5,833,700; and 5,921,997 to Fogelberg et al. The Fogelberg et al. references teach a dip applier with a feeding mechanism that utilizes a reciprocating feed bar to feed a serial stack of clips. A feeder shoe may operably engage with and move with the distally moving feed bar and may slidingly engage with the proximally moving feed bar. Thus, the feeder shoe may index or push the stack of clips distally with the distally moving feed bar and remains stationary relative to the proximally moving feed bar. A valving mechanism may be also required to separate the distal-most clip from the stack and to hold the stack stationary as the distal most clip may be applied onto a vessel. Whereas the Fogelberg et al. references teach a reciprocating feeding mechanism with a single reciprocating member, they do not teach the use of the clip applier in the attachment of hernia mesh, nor do they teach the individual driving or feeding of each clip by a moving member. 
     Another fastener feeding mechanism that uses reciprocation is that disclosed in U.S. Pat. No. 4,325,376 to Klieman et al. A clip applier that stores a plurality of clips in a serial fashion within a clip magazine is disclosed. The clips are in a stack wherein the proximal most clip may be pushed or fed distally by a pawl that may be ratcheted or indexed distally by a reciprocating member or ratchet blade with each actuation of the instrument. As the pawl indexes distally, it can push the stack of clips distally. A secondary valving mechanism may be also described. Thus, the feeding mechanism of Klieman et al. teaches the use a single reciprocating member and pawl to push or feed the stack of clips distally, and may require a secondary valving mechanism to feed the distal most clip. 
     U.S. Pat. No. 3,740,994 to DeCarlo Jr. describes a novel reciprocating feeding mechanism that may index a plurality of staples or clips, and may ready them for discharge by reciprocating one of a pair of opposing leaf spring assemblies. The staples reside serially within a guide rail with a fixed leaf spring assembly extending into the plane of the guide rail. A reciprocating leaf spring assembly may opposedly extend inwardly towards the fixed leaf spring assembly. As the reciprocating leaf spring assembly moves distally, each of individual leaf springs of the assembly may engage a staple and move it distally. The distally moving staples deflect the local individual leaf springs of the fixed leaf spring assembly, and the deflected leaf springs may return to the un-deflected position after passage of the staple. As the moving leaf spring assembly moves proximally, the leaf springs of the fixed leaf spring assembly hold the staples stationary and prevent proximal movement thereof. A secondary guide rail and valving mechanism may be provided to separate a single staple from the stack for forming and can hold the stack of staples stationary as the single clip is formed. 
     Additionally, similar feeding mechanisms are disclosed in U.S. Pat. No. 4,478,220 to DiGiovanni et al. and U.S. Pat. No. 4,471,780 to Menges et al. Both of these related patents teach a reciprocating feeding mechanism that uses one fixed member and one reciprocating member to feed or index a plurality of clips distally. Angled flexible fingers may be hingedly attached to the reciprocating member and operatively engage the clips when moving distally, and slidingly engage with the clips when moving proximally. The angled flexible fingers within the fixed member deflect out of the way when the clips move distally and spring up to stop proximal movement of the clip after the clip has passed. A secondary valving mechanism is also disclosed. 
     Commonly assigned U.S. Patent Application Publication No. 2002/0068947, the disclosure of which is hereby incorporated by reference herein, teaches a device for delivering a plurality of individual surgical fasteners. In one embodiment, the delivery device includes a drive mechanism having distal and proximal ends. The drive mechanism has a moving member and a fixed opposing member, whereby the moving member is moveable proximally and distally with respect to the delivery device. The moving member has a sharpened distal end for piercing tissue. The device includes at least one surgical fastener located between the first and the second members. Each of the at least one surgical fasteners has a proximal end and a distal end. The device also has an actuator having at least two sequential positions. A first position for moving the moving member distally and piercing tissue, and a second position for moving the moving member proximally, thereby deploying the distal end of the fastener. 
     Tacks for fixing meshes used laparoscopically have generally been made of metal, such as stainless steel, nitinol, or titanium. The metal tacks were necessary to provide for sufficient holding strength, penetration of various prosthetic meshes, and for ease of manufacture. Until recently, there were no absorbable tacks available on the market, and surgeons could only use absorbable sutures in order to provide a fixation means that did not permanently stay in the body. However, using sutures is exceedingly difficult for laparoscopic procedure, and so they are generally not used unless the repair is done in an open fashion. With surgical trends leading to more minimally invasive techniques with minimum foreign body accumulation, an absorbable tack with minimum profile that can be applied laparoscopically is needed. 
     In spite of the above advances, there remains a need for further improvements. In particular, there remains a need for surgical fasteners having a minimum profile, surgical fasteners that may be applied laparoscopically, and surgical fasteners that are absorbable. 
     SUMMARY OF THE INVENTION 
     In one embodiment, the present invention discloses an applicator instrument and methods for consistently deploying surgical fasteners. In one embodiment, the applicator instrument is used to hold a prosthetic device such as surgical mesh in place over tissue. In one embodiment, the applicator instrument includes a mechanism for positioning a surgical fastener in line with a firing rod. The applicator instrument preferably includes a firing system that initially advances the firing rod toward the surgical fastener at a first speed. In one embodiment, energy may be stored in the firing system as the firing rod is advanced or piloted toward the surgical fastener. The firing system desirably engages the surgical fastener with the firing rod while maintaining the surgical fastener in a stationary position. The firing system preferably releases the stored energy to advance the firing rod at a second speed that is greater than the first speed to deploy the surgical fastener into tissue. In one embodiment, one surgical fastener is dispensed during one cycle of the firing system. A plurality of surgical fasteners may be dispensed for securing a prosthesis such as a surgical mesh to tissue. 
     In one embodiment, an applicator instrument for dispensing surgical fasteners preferably includes a housing, and an elongated shaft extending from the housing having a proximal end coupled with the housing and a distal end remote therefrom. The applicator instrument desirably includes a firing system for dispensing surgical fasteners from the distal end of the elongated shaft. The firing system preferably includes a firing rod disposed in the elongated shaft, and desirably has a firing cycle with a first stage for advancing the firing rod toward the distal end of the elongated shaft at a first rate of speed and a second stage for advancing the firing rod toward the distal end of the elongated shaft at a second rate of speed that is greater than the first rate of speed. 
     In one embodiment, a distal end of the firing rod includes an insertion fork. The applicator instrument is adapted to slowly pilot the insertion fork into a lead surgical fastener followed by quick firing of the surgical fastener through a prosthetic device and into tissue. Prior art devices rapidly advance a pushing element in one motion through a fastener in a hammer-like manner while continuing to drive the fastener into tissue, or slowly engage a fastener at the same rate for slowly driving the fastener into tissue. The first type of prior art device is limited in its ability to engage the fastener in a secure manner to assure the fastener&#39;s proper insertion into tissue. The first “hammer-like” prior art device may also damage the surgical fastener due to impact force or may require the use of a massive fastener adapted to withstand impact forces. The second type of prior art device does not advance the fastener fast enough to avoid tissue tenting and to enable proper tissue penetration. Both of these prior art approaches do not lend themselves to consistent and repeatable fastener penetration into tissue. In one embodiment, the present invention solves these limitations by slowly piloting an insertion fork into a lead surgical fastener, which assures proper engagement of the insertion fork with the surgical fastener. After proper engagement, the present invention also provides for quick firing of the surgical fastener through a prosthetic device and into tissue. As a result, each surgical fastener is preferably inserted the same way regardless of the speed of a user&#39;s trigger squeeze. 
     In one embodiment, the distal end of the firing rod is coupled with at least one of the surgical fasteners during the first stage of the firing cycle, and the distal end of the firing rod dispenses the at least one of the surgical fasteners from the distal end of the elongated shaft during the second stage of the firing cycle. The firing system may include an energy storing element such as a firing spring coupled with the firing rod, whereby the firing system is adapted to store energy in the firing spring before the second stage of the firing cycle and transfer the stored energy from the firing spring to the firing rod during the second stage of the firing cycle. In certain embodiments, the energy storing element may also include a pneumatic device, a hydraulic device and/or a compressed gas device. 
     In one embodiment, the applicator instrument includes an actuator movable between a first position and a second position for activating the firing system. The actuator may be a squeezable trigger that activates the firing system. In one embodiment, the firing spring is at least partially compressed prior to the first stage of the firing cycle, and the firing rod advances distally at a rate that is proportional to movement of the actuator during the first stage of the firing cycle. The firing spring is preferably compressible for storing energy therein as the actuator moves from the first position to the second position. The energy stored in the firing spring is released during the second stage of the firing cycle for rapidly driving the firing rod toward the distal end of the elongated shaft. Although many of the embodiments disclosed herein refer to a “firing spring,” it is contemplated that other energy storing devices, such as those disclosed above may be used and still fall within the scope of the present invention. 
     In one embodiment, the firing system preferably includes a release latch that constrains the firing rod from moving toward the distal end of the elongated shaft after the first stage of the firing cycle and before the second stage of the firing cycle. At a preferred stage of the firing cycle, and preferably after energy is stored in the firing system, the release latch desirably releases the firing rod for moving distally. 
     In one embodiment, the applicator instrument may include an advancer coupled with the actuator and extending through the elongated shaft for advancing the surgical fasteners toward the distal end of the elongated shaft. The advancer is preferably adapted to move toward the distal end of the elongated shaft as the actuator moves from the first position to the second position. The advancer is preferably adapted to move toward the proximal end of the shaft as the actuator moves from the second position to the first position. The advancer desirably includes a plurality of advancer tabs projecting toward a distal end of the advancer, whereby each advancer tab is adapted to engage one of the surgical fasteners for urging the surgical fasteners toward the distal end of the elongated shaft. 
     In one embodiment, the surgical fasteners are disposed within the elongated shaft for being urged toward the distal end of the elongated shaft by the advancer. In one embodiment, a most distal one of the surgical fasteners is engageable by the staging assembly for aligning the most distal one of the surgical fasteners with the distal end of the firing rod. In one embodiment, the distal end of the firing rod includes an insertion fork having spaced tines that are adapted to engage the most distal one of the surgical fasteners. 
     In one embodiment, a surgical fastener includes a first leg having a distal end with a first insertion tip, a proximal end, and a first insertion tool seating surface located adjacent the first insertion tip. The surgical fastener preferably includes a second leg having a distal end with a second insertion tip, a proximal end, and a second insertion tool seating surface located adjacent the second insertion tip. The surgical fastener also desirably includes a bridge connecting the proximal ends of the first and second legs for forming a closed proximal end of the surgical fastener. In one embodiment, tines of an insertion fork are preferably seatable against the first and second insertion tool seating surfaces of the surgical fastener for applying an insertion force upon the surgical fastener at a location that is closer to the distal end of the surgical fastener than the proximal end of the surgical fastener. 
     In one embodiment, an applicator instrument may include a lockout system coupled with the firing system for preventing operation of the firing system after all of the surgical fasteners have been dispensed. In one embodiment, the lockout system locks an actuator or trigger in a closed position after all of the surgical fasteners have been dispensed. 
     In one embodiment, an applicator instrument for dispensing surgical fasteners includes a housing having a handle section and a trigger, and an elongated shaft for dispensing the surgical fasteners. The elongated shaft includes a proximal end coupled with the housing and a distal end remote therefrom. The elongated shaft may include a surgical fastener delivery conduit extending therethrough for delivering or dispensing the surgical fasteners from the distal end of the elongated shaft. The applicator instrument preferably includes a firing system actuatable by the trigger, whereby the firing system includes a firing rod and an energy storing assembly coupled with the firing rod. In one embodiment, the firing system desirably has a firing cycle including a first stage for moving the firing rod toward the distal end of the elongated shaft at a first speed and a second stage for transferring energy from the energy storing assembly to the firing rod for driving the firing rod toward the distal end of the elongated shaft at a second speed that is greater than the first speed. In one embodiment, energy may be stored in the energy storing assembly during the initial piloting stage when the firing rod moves forward at the first speed. 
     In one embodiment, the applicator instrument may include a staging assembly disposed within the elongated shaft for aligning the surgical fasteners with a distal end of the firing rod. The surgical fasteners are preferably advanced through an elongated conduit in the elongated shaft and toward the distal end of the elongated shaft. The applicator instrument may include an advancer coupled with the firing system for incrementally advancing the surgical fasteners toward the distal end of the elongated shaft each time the trigger is squeezed. In one embodiment, the firing rod preferably moves distally as the trigger is squeezed from an open position to a closed position, and the firing rod moves proximally as the trigger returns from the closed position to the open position. 
     In one embodiment, a method of dispensing surgical fasteners includes providing an applicator instrument having a housing, an elongated shaft projecting from the housing, and a firing system including a firing rod for dispensing surgical fasteners from a distal end of the elongated shaft. The method preferably includes aligning a first surgical fastener with a distal end of the firing rod, advancing the distal end of the firing rod toward the first surgical fastener at a first speed for engaging the surgical fastener, and after the firing rod advancing step and while constraining the firing rod from moving toward the distal end of the elongated shaft, storing energy in the firing system. The method desirably includes releasing the firing rod for distal movement and transferring the stored energy to the firing rod for driving the firing rod distally at a second speed that is greater than the first speed so as to dispense the first or lead surgical fastener from the distal end of the elongated shaft. 
     In one embodiment, the firing system desirably includes a compressible firing spring coupled with the firing rod, and an actuator coupled with the firing spring for selectively compressing the firing spring for storing energy in the firing system. In one embodiment, the energy for advancing the firing rod is stored in a spring. In one embodiment, the spring is a firing spring that is preferably pre-loaded or pre-compressed prior to actuation of the applicator instrument. 
     In one embodiment, the applicator instrument includes a lockout mechanism to prevent operation of the applicator instrument when no more surgical fasteners are available (e.g., all of the surgical fasteners have been dispensed). In one embodiment, the lockout mechanism preferably locks the trigger in a closed position when the device is empty. The lockout mechanism may also include a mechanical or electronic counter that displays how many surgical fasteners have been dispensed and/or how many surgical fasteners remain available. 
     In one embodiment, the distal end of the applicator instrument, such as the distal end of the elongated shaft, includes one or more markings for orientation. The distal end of the elongated shaft may also include one or more features provided on the distal tip to assist with device orientation and/or to capture one or more mesh strands. In one embodiment, the applicator instrument includes one or more protuberances to capture one or more strands of mesh. 
     In one embodiment, a surgical fastener includes a first leg having a distal end, a proximal end and a first insertion tip at the distal end of the first leg. The surgical fastener preferably includes a second leg having a distal end, a proximal end, and a second insertion tip at the distal end of the second leg. A bridge desirably connects the proximal ends of the first and second legs for forming a closed end of the surgical fastener. The first insertion tip preferably includes a first insertion tool seating surface, and the second insertion tip preferably includes a second insertion tool seating surface. 
     In one embodiment, the first and second legs extend along respective longitudinal axes, and the first and second insertion tips are skewed or angulated outwardly relative to the respective longitudinal axes of the first and second legs. As a result, in one embodiment, the spacing between the insertion tips is greater than the spacing between the first and second legs, which may enhance the capture of strands or fibers between the legs. In one embodiment, at least one of the first and second insertion tips includes a blunt distal piercing point. In one embodiment, both of the first and second insertion tips include blunt distal piercing points. 
     In one embodiment, the first insertion tip includes a proximal end with the first insertion tool seating surface, and the second insertion tip includes a proximal end including the second insertion tool seating surface. In one embodiment, the first insertion tool seating surface is closer to the distal end of the first leg than the proximal end of the first leg, and the second insertion tool seating surface is closer to the distal end of the second leg than the proximal end of the second leg. The first and second insertion tool seating surfaces preferably face toward the proximal ends of the respective first and second legs and are adapted to be engaged by the distal end of an insertion tool, such as the distal ends of tines or an insertion fork. 
     In one embodiment, the first insertion tool seating surface includes an opening facing toward the proximal end of the first leg, and the second insertion tool seating surface includes a second opening facing toward the proximal end of the second leg. The openings in the insertion tool seating surfaces may be blind openings that are closed at one end (e.g., at the distal end). In one embodiment, the first insertion tool seating surface includes a first aperture that extends completely through the first insertion tip, and the second insertion tool seating surface includes a second aperture that extends completely through the second insertion tip. 
     In one embodiment, the first leg of a surgical fastener preferably includes a first alignment guide extending between the proximal end of the first leg and the first insertion tool seating surface, and the second leg preferably includes a second alignment guide extending between the proximal end of the second leg and the second insertion tool seating surface. The first alignment guide on the first leg is preferably in substantial alignment with the first insertion tool seating surface, and the second alignment guide on the second leg is preferably in substantial alignment with the second insertion tool seating surface. The first and second alignment guides may include ribs extending between the distal and proximal ends of the legs, grooves extending between the distal and proximal ends of the legs, or a combination of ribs and grooves. 
     In one embodiment, the first and second insertion tips have distal ends that are staggered from one another, which may reduce the amount of force required to anchor the surgical fastener in tissue. In one embodiment, the bridge adjacent the proximal end of the surgical fastener defines a third insertion tool seating surface engageable by a surface on an insertion tool. 
     In one embodiment, the first leg of a surgical fastener includes a first barb projecting toward the proximal end of the first leg, and the second leg of the surgical fastener includes a second barb projecting toward the proximal end of the second leg, whereby the first and second barbs are staggered from one another. In one embodiment, the first and second barbs on the respective first and second legs project outwardly away from one another. In another embodiment, the first and second barbs on the respective first and second legs project inwardly toward one another. 
     In one embodiment, a surgical fastener for anchoring prosthetic devices to tissue includes a first leg having a distal end, a proximal end, a first alignment guide extending between the distal and proximal ends of the first leg, and a first insertion tip at the distal end of the first leg. The surgical fastener desirably includes a second leg having a distal end, a proximal end, a second alignment guide extending between the distal and proximal ends of the second leg, and a second insertion tip at the distal end of the second leg. The surgical fastener preferably includes a bridge connecting the proximal ends of the first and second legs for forming a closed end of the surgical fastener. 
     In one embodiment, the first insertion tip has a proximal end with a first insertion tool seating surface and the second insertion tip has a proximal end with a second insertion tool seating surface. The first and second insertion tool seating surfaces may include convex surfaces facing toward the proximal ends of the first and second legs, concave surfaces facing toward the proximal ends of the first and second legs, openings facing toward the proximal ends of the first and second legs, blind vias facing toward the proximal ends of the first and second legs, and/or apertures extending through the first and second insertion tips. 
     In one embodiment, the first and second alignment guides are selected from the group of alignment guides including ribs extending between the distal and proximal ends of the legs, and grooves extending between the distal and proximal ends of the legs. The first and second alignment guides are substantially aligned with the respective first and second insertion tool seating surfaces. In one embodiment, the first and second seating surfaces are desirably closer to the distal end of the surgical fastener than the proximal end of the surgical fastener. 
     In one embodiment, an applicator instrument for dispensing surgical fasteners includes a housing, and an elongated shaft extending from the housing, the elongated shaft having a proximal end, a distal end, and a longitudinal axis extending between the proximal and distal ends. The applicator instrument desirably includes a firing rod disposed inside the elongated shaft and that is moveable within a first plane between a retracted position and an extended position. The elongated shaft preferably includes an advancer disposed inside the elongated shaft that is moveable within a second plane between a retracted position and an extended position. The applicator instrument preferably includes a staging assembly located adjacent the distal end of the elongated shaft that is adapted to align surgical fasteners with a distal end of the firing rod. The staging assembly is preferably held below the second plane by the advancer when the advancer is in the extended position, and the staging assembly is preferably adapted to move into at least partial alignment with the distal end of the firing rod when the advancer moves toward or is in the retracted position. 
     The applicator instrument preferably includes a plurality of surgical fasteners disposed within the elongated shaft, whereby the advancer is adapted to move the surgical fasteners one position toward the distal end of the elongated shaft each time the advancer moves from the retracted position to the extended position. In one embodiment, the plurality of surgical fasteners desirably include a lead surgical fastener located adjacent the distal end of the elongated shaft and a series of trailing surgical fasteners located between the lead surgical fastener and the proximal end of the elongated shaft. 
     In one embodiment, the advancer includes a plurality of advancer tabs whereby each of the advancer tabs is preferably adapted to engage one of the surgical fasteners for urging the surgical fasteners toward the distal end of the elongated shaft as the advancer moves from the retracted position to the extended position. In one embodiment, the advancer tabs project toward the distal end of the elongated shaft. In one embodiment, the advancer is moveable into the extending position for moving the lead surgical fastener into contact with the staging assembly. 
     In one embodiment, a floor of the elongated shaft includes a plurality of anti-backup tabs, whereby the anti-backup tabs are adapted to prevent the surgical fasteners in the elongated shaft from moving toward the proximal end of the elongated shaft. In one embodiment, the anti-backup tabs project toward the distal end of the elongated shaft. 
     In one embodiment, the advancer urges the lead surgical fastener into contact with the staging assembly, and the staging assembly is adapted to lift the lead surgical fastener into substantial alignment with the distal end of the firing rod as the advancer returns to the retracted position. 
     In one embodiment, the elongated shaft includes at least one guide surface adapted to engage and/or contact the firing rod for guiding distal and proximal movement of the firing rod. In one embodiment, the at least one guide surface includes a pair of opposing guide flanges adapted to engage opposites sides of the firing rod for guiding distal and proximal movement of the firing rod. 
     In one embodiment, the distal end of the firing rod includes an insertion tool, such as an insertion fork, having a first tine with a distal end adapted to engage the first insertion tool seating surface, and a second tine having a distal end adapted to engage the second insertion tool seating surface. In one embodiment, the bridge of the surgical fastener has a proximal face defining a third insertion tool seating surface, and the insertion tool includes a distal surface extending between the proximal ends of the first and second tines adapted to engage the third insertion tool seating surface. 
     In one embodiment, an applicator instrument for dispensing surgical fasteners includes a housing, an elongated shaft extending from the housing, the elongated shaft including a proximal end and a distal end remote therefrom, and a plurality of surgical fasteners disposed within the elongated shaft for being dispensed from the distal end of the elongated shaft. The applicator instrument preferably includes an advancer disposed inside the elongated shaft that is moveable between the proximal and distal ends of the elongated shaft, whereby the advancer is adapted to shift the surgical fasteners one position closer to the distal end of the elongated shaft each time the advancer moves distally. The applicator instrument preferably includes a firing rod disposed inside the elongated shaft and overlying the advancer, the firing rod being moveable between the proximal and distal ends of the elongated shaft. The applicator instrument desirably includes a staging assembly located adjacent the distal end of the elongated shaft that is adapted to receive a leading one of the surgical fasteners from the advancer as the advancer moves distally and to shift the received leading surgical fastener into substantial alignment with a distal end of the firing rod when the advancer moves proximally. 
     In one embodiment, the distal end of the firing rod is adapted to move distally at a first rate of speed for engaging the leading surgical fastener, and then to move distally at a second rate of speed that is faster than the first rate of speed for dispensing the leading surgical fastener from the distal end of the elongated shaft. 
     In one embodiment, the first leg of the surgical fastener includes a first alignment guide extending between the proximal end of the first leg and the first insertion tool seating surface, and the second leg of the surgical fastener includes a second alignment guide extending between the proximal end of the second leg and the second insertion tool seating surface. The first alignment guide on the first leg is preferably in substantial alignment with the first insertion tool seating surface and the second alignment guide on the second leg is preferably in substantial alignment with the second insertion tool seating surface. In one embodiment, the first alignment guide includes a first rib extending between the distal and proximal ends of the first leg, and the second alignment guide includes a second rib extending between the distal and proximal ends of the second leg, whereby the first and second tines at the distal end of the firing rod have opposing inner surfaces with opposing grooves adapted to engage the first and second ribs on the respective first and second legs for engaging the surgical fastener with the insertion tool. 
     In one embodiment, a method of dispensing a surgical fastener includes providing an applicator instrument having a housing and an elongated shaft extending from the housing, the elongated shaft including a proximal end and a distal end remote therefrom, and providing surgical fasteners in the elongated shaft for being dispensed one at a time from the distal end of the elongated shaft. The method preferably includes advancing the surgical fasteners within a first plane toward the distal end of the elongated shaft. After advancing a leading one of the surgical fasteners to a location adjacent the distal end of the elongated shaft, the leading surgical fastener is preferably shifted from the first plane into a second plane in which the leading surgical fastener is substantially aligned with a distal end of a firing rod. The firing rod is then desirably moved distally for engaging the leading surgical fastener with the firing rod and dispensing the leading surgical fastener from the distal end of the elongated shaft. 
     In one embodiment, the method includes loading the surgical fasteners in the elongated shaft. In one embodiment, the step of moving the firing rod distally includes a first distal movement stage during which the firing rod moves distally at a first rate of speed for engaging the leading surgical fastener, and a second distal movement stage that follows the first distal movement stage during which the firing rod moves distally at a second rate of speed for dispensing the leading surgical fastener from the distal end of the elongated shaft, whereby the second rate of speed is greater than the first rate of speed. 
     In one embodiment, after the advancing step, and while constraining the firing rod from moving toward the distal end of the elongated shaft, energy is stored in the firing system. The firing rod may later be unconstrained or released so that it is able to move in the distal direction and the stored energy may be transferred to the firing rod for driving the firing rod distally at the second speed that is greater than the first speed for dispensing the first surgical fastener from the distal end of the elongated shaft. 
     In one embodiment, the firing system includes an energy storing element such as a compressible firing spring coupled with the firing rod, and an actuator coupled with the firing spring for selectively compressing the firing spring so as to store energy in the firing system. 
     In one embodiment, a method of affixing a prosthesis to tissue includes providing an applicator instrument for dispensing surgical fasteners having a housing, an elongated shaft extending from the housing, the elongated shaft having a proximal end coupled with the housing and a distal end remote therefrom, and a firing system for dispensing surgical fasteners from the distal end of the elongated shaft. The firing system preferably includes a firing rod disposed in the elongated shaft, the firing system having a firing cycle with a first stage for advancing the firing rod toward the distal end of the elongated shaft at a first rate of speed and a second stage for advancing the firing rod toward the distal end of the elongated shaft at a second rate of speed that is greater than the first rate of speed. The method preferably includes positioning a prosthesis, such as a surgical mesh, over tissue, and operating the applicator instrument for dispensing at least one of the surgical fasteners from the distal end of the elongated shaft for affixing the prosthesis to the tissue. In one embodiment, a plurality of surgical fasteners may be dispensed for affixing the prosthesis to the tissue. 
     In one embodiment, a firing system for an applicator instrument adapted to dispense surgical fasteners includes a housing, an elongated shaft extending from the housing, a firing rod disposed within the elongated shaft, a firing rod release engageable with the firing rod for preventing distal movement of the firing rod during at least one stage of a firing cycle, a trigger mounted to the housing, and a firing spring having a first end connected with the firing rod and a second end adapted for being sequentially coupled and decoupled from the trigger during the firing cycle. In one embodiment, the firing cycle desirably includes an initial stage in which the trigger is open and decoupled from the firing spring and the firing spring is at least partially compressed, and a piloting stage during which the firing rod release is disengaged from the firing rod for enabling distal movement of the firing rod. The trigger is preferably compressible a first distance for coupling the trigger with the firing spring for moving the at least partially compressed firing spring distally, which, in turn, moves the firing rod distally at a first rate of speed that is proportional to the movement of the trigger. In one embodiment, an energy storing element such as a pneumatic or hydraulic device may be used in place of or in combination with the firing spring. 
     In one embodiment, the firing cycle includes, after the piloting stage, an energy storing stage in which the firing rod release engages the firing rod for preventing distal movement of the firing rod, and the trigger is further moveable a second distance for further compressing and storing energy in the firing spring. The firing cycle preferably includes a firing stage in which the firing rod release disengages from the firing rod so that the firing rod is free to move toward the distal end of the elongated shaft and the firing spring transfers the energy stored therein to the firing rod for rapidly advancing the firing rod toward the distal end of the elongated shaft at a second rate of speed that is greater than both the first rate of speed and the movement of the trigger. 
     In one embodiment, the firing cycle includes a decoupling stage during which the trigger is further compressible a third distance for decoupling the trigger from the firing spring whereupon the firing rod is free to move toward the proximal end of the elongated shaft. 
     In one embodiment, the firing system includes an advancer disposed within the elongated shaft and that is moveable in proximal and distal directions along the elongated shaft. The firing cycle preferably includes, after the firing stage, a surgical fastener advancing stage during which the trigger is further compressible a fourth distance for moving the advancer toward the distal end of the elongated shaft so as to move the surgical fasteners toward the distal end of the elongated shaft. 
     In one embodiment, the firing cycle preferably includes, after the surgical fastener advancing stage, a retraction stage during which the trigger moves from a compressed position to the open position of the initial stage for moving the advancer in a proximal direction. 
     In one embodiment, the firing system preferably includes a spring block disposed within the housing and engageable with a proximal end of the firing spring. The spring block is preferably adapted to move proximally and distally along the longitudinal axis defined by the elongated shaft. In one embodiment, during the energy storing stage, the trigger is coupled with the spring block for moving the spring block distally, which, in turn, further compresses the firing spring. 
     In one embodiment, the firing system includes a primary latch coupled with the trigger. The primary latch is preferably adapted to couple the trigger with the spring block during the piloting, energy storing, and firing stages, and decouple the trigger from the spring block during the decoupling, surgical fastener advancing, and retraction stages. In one embodiment, at the beginning of the firing stage, the spring block contacts the firing rod release for disengaging the firing rod release from the firing rod so that the firing rod may move distally. 
     In one embodiment, a firing system for a surgical fastener applicator instrument includes a housing and an elongated shaft extending from the housing. The firing system desirably includes a firing rod disposed within the elongated shaft and being moveable proximally and distally along a longitudinal axis, a firing spring block disposed within the housing and being adapted to move in proximal and distal directions along the longitudinal axis, and a firing spring having a distal end connected with the firing rod and a proximal end engageable with the firing spring block. The firing system preferably includes a trigger mounted to the housing for driving the firing system, whereby the trigger includes a primary latch for sequentially coupling and decoupling the trigger from the firing spring block during a firing cycle. 
     In one embodiment, the firing cycle preferably includes an initial stage in which the trigger is open, the trigger is decoupled from the firing spring block, and the firing spring is at least partially compressed. The firing system preferably includes a piloting stage in which the firing rod is free to move distally, and the trigger is compressible a first distance for coupling the trigger with the firing spring block so as to move the at least partially compressed firing spring distally, which, in turn, moves the firing rod distally at a first rate of speed that is proportional to the movement of the trigger. In one embodiment, the compression level of the firing spring remains unchanged during the piloting stage. In one embodiment, the firing spring may be compressed during the piloting stage. 
     In one embodiment, the firing cycle includes, after the piloting stage, an energy storing stage in which the trigger is further compressible a second distance for further compressing and/or storing energy in the firing spring while the firing rod release engages the firing rod for preventing distal movement of the firing rod. 
     The firing cycle preferably includes, after the energy storing stage, a firing stage in which the firing rod release disengages from the firing rod so that the firing rod is free to move toward the distal end of the elongated shaft and the firing spring transfers the energy stored therein to the firing rod for rapidly advancing the firing rod toward the distal end of the elongated shaft at a second rate of speed that is greater than the first rate of speed. 
     The firing cycle preferably includes, after the firing stage, a decoupling stage during which the trigger is further compressible a third distance for decoupling the trigger from the firing spring and the firing rod so that said firing rod may move proximally. 
     In one embodiment, the firing system includes an advancer disposed within the elongated shaft. The advancer is preferably moveable between the proximal and distal ends of the elongated shaft for moving surgical fasteners toward the distal end of the elongated shaft. The firing cycle may include, after the firing stage, a surgical fastener advancing stage during which the trigger is further compressible a fourth distance for moving the advancer toward the distal end of the elongated shaft, which, in turn, moves the surgical fasteners toward the distal end of the elongated shaft. 
     In one embodiment, the firing system preferably includes a spring block disposed within the housing. The spring block is preferably adapted to move proximally and distally along the longitudinal axis. The spring block preferably engages the firing spring, and during the energy storing stage, the trigger is coupled with the spring block for moving the spring block distally, which, in turn, compresses the firing spring. The firing system may also include a primary latch coupled with the trigger. The primary latch is preferably adapted to couple the trigger with the spring block during the piloting, energy storing, and firing stages, and decouple the trigger from the spring block during the decoupling, surgical fastener advancing, and retraction stages. 
     In one embodiment, a method of dispensing surgical fasteners from an applicator instrument includes providing a housing, an elongated shaft extending from the housing, a firing rod disposed within the elongated shaft that is moveable proximally and distally for dispensing surgical fasteners from the distal end of the elongated shaft, a trigger for operating the applicator instrument, and an energy storing element disposed between the trigger and the firing rod. The method preferably includes compressing the trigger for piloting the firing rod toward the distal end of the elongated shaft at a first rate of speed, and after piloting the firing rod, preventing the firing rod from moving distally while further compressing the trigger for storing energy in the energy storing element. The method preferably includes releasing the firing rod for distal movement, and transferring the energy stored in the energy storing element to the firing rod for moving the firing rod toward the distal end of the elongated shaft at a second rate of speed that is greater than the first rate of speed. In one embodiment, during the piloting stage, the firing rod moves distally at a first rate of speed that is proportional to the movement of the trigger. 
     In one embodiment, the energy storing element is a firing spring disposed between the trigger and the firing rod. In one embodiment, the firing spring is at least partially compressed before piloting the firing rod toward the distal end of the elongated shaft and the firing spring has a compression level that does not change during the piloting step. As noted herein, the energy storing element may also include a pneumatic device, a hydraulic device, a compressed gas device, or combinations thereof. 
     In one embodiment, the method includes providing a plurality of surgical fasteners within the elongated shaft, and providing an advancer disposed within the elongated shaft. The advancer is preferably coupled with the trigger and is adapted to move toward the distal end of the elongated shaft when the trigger is compressed and move toward the proximal end of the elongated shaft when the trigger is opened. The method preferably includes compressing the trigger for moving the advancer toward the distal end of the elongated shaft, whereby the distally moving advancer shifts each of the surgical fasteners one position closer to the distal end of the elongated shaft. In one embodiment, the trigger may not return to the open position until it is completely squeezed to the closed position. 
     The applicator instrument may be made in various lengths and diameters. Shorter lengths may be more suitable for open surgical procedures. In one embodiment, the diameter of the shaft of the applicator instrument is preferably between about 3-10 mm, and more preferably between about 3-5 mm. In one embodiment, the applicator instrument includes more than one surgical fastener and may be pre-loaded with a plurality of fasteners such as 10, 25, 100 or more surgical fasteners. In one embodiment, the applicator instrument is pre-loaded with 10 surgical fasteners for open procedures. In one embodiment, the applicator instrument is pre-loaded with 30 surgical fasteners for standard laparoscopic procedures. In one embodiment, the surgical fasteners may be housed in cartridges for easy loading and/or re-loading. In certain embodiments, the applicator instrument may include a stay suture device as part of the handle, or a device/handle that dispenses a skin adhesive such as the tissue adhesive sold under the trademark Dermabond™ for use for trocar wound closure. 
     In one embodiment, a surgical fastener preferably has a very small profile, may be semi-rigid, and may be fully resorbable. The resorbable nature of the surgical fastener preferably decreases chronic pain caused by permanent fixation. In addition, the low profile of the surgical fastener reduces adhesions of the viscera. As is well known to those skilled in the art, it is very common to see excessive adhesions caused by permanent tackers during re-ops. 
     In one embodiment, a surgical fastener provides two points of fixation with a connecting back span extending between the two points of fixation so as to spread the tissue holding forces over a greater area. The span between the two points of fixation makes it possible to span the tack across the edge of a mesh, which minimizes exposure of tissue to mesh ends that may be the source of tissue irritation. 
     In one embodiment, an applicator instrument deploys one or more soft tissue surgical fasteners. The surgical fasteners provide low profile soft tissue fixation of prosthetic materials onto the human body. In one embodiment, the applicator instrument provides for tension-free laparoscopic hernia repair using mesh. In one embodiment, a prosthetic mesh is placed over an abdominal defect and attached to tissue with either permanent or resorbable surgical fasteners, In one embodiment, the surgical fasteners are made of relatively soft materials such as plastic or absorbable polymers. 
     The present invention provides a number of benefits. In one embodiment, male features on a surgical fastener mate with female features on an inserter device, which reduces the cost for molding the surgical fasteners. In one embodiment, pins or tines on an insertion device provide rigidity during insertion of the surgical fastener and leaves less absorbable mass in tissue as compared with tack systems and methods that do not use inserter pins or tines for stiffening. 
     In one embodiment, the surgical fasteners have rounded proximal ends. Specifically, each surgical fastener has a connecting bridge or back span at the proximal end of the surgical fastener that is rounded and results in a very low profile after insertion into tissue. The low profile design and small diameter of the surgical fastener results in the surgical fastener having the appearance of a suture stitch once the surgical fastener is implanted. The lower profile also preferably reduces the possibility of forming adhesions in the body. 
     In one embodiment, surgical fasteners have insertion pin holes or recesses formed in the proximal portion of each insertion tip of the surgical fasteners. The insertion pin holes, or recesses are preferably located directly over the center of each insertion tip. As a result, the insertion pin holes, or recesses are substantially aligned with the insertion tip to avoid tip bending and to direct forces for insertion directly behind each of the penetrating insertion tips. 
     In prior art fasteners having a single head, the single head may fall through the large pores of the prosthetic mesh. In one embodiment, surgical fasteners of the present invention have a connecting back span or bridge between two insertion tips. The connecting back span or bridge makes the surgical fastener more compatible for use with large pore surgical prosthetic meshes. 
     In one embodiment, surgical fasteners have blind holes that are filled by metal inserters, probes, or tines during application. The metal inserters preferably provide rigidity to the surgical fastener during insertion, allowing the surgical fastener itself to be made of a softer material, such as an absorbable polymer. In another embodiment, rigid inserters, probes or tines support the tips and/or legs of the surgical fastener during anchoring into tissue. 
     In one embodiment, surgical fasteners have lead-in channels that are aligned with blind holes or tool seating surfaces. The lead-in channels are axially open on at least one side, which enables less material to be used for forming the surgical fasteners, and which provides a space for tissue in-growth to maximize fixation strength. 
     In one embodiment, surgical fasteners have staggered tips, which preferably reduce the necessary penetration force by staggering the peak forces encountered during insertion. In one embodiment, surgical fasteners have staggered barbs improve anchoring in tissue by requiring greater pull out forces. 
     In one embodiment, surgical fasteners have barbs set out of plane from each other, which increase the force necessary for pull out of the surgical fasteners. In one embodiment, surgical fasteners have insertion tips with through openings extending therethrough. The through openings are preferably adapted to receive one or more needles for needle-assisted insertion. 
     In one embodiment, surgical fasteners have one or more barbs with “living hinge” features. The living hinges enable the barbs to collapse easily during insertion but flare outwardly during attempts to remove the surgical fasteners. 
     In one embodiment, the pointed insertion tips of the surgical fasteners are cut or have defined chisel points, which enable the insertion tips to cut during insertion, thereby improving the ability of the surgical fasteners to penetrate difficult materials such as GORE® dual mesh. Insertion tips having compound cut or chiseled angles may also be used to allow for stronger, yet shorter tip designs. 
     In one embodiment, surgical fasteners may have conical-shaped insertion tips that create a puncture rather than a cut, thereby improving holding force. Although the present invention is not limited by any particular theory of operation, it is believed that conical-shaped insertion tips create only a single point of stress concentration, whereby the section of the surgical fastener that follows must expand the hole radially. It is believed that this may make it harder for the rest of the surgical fastener to make it through the hole, but may potentially increase retention forces by making a tighter hole. 
     In one embodiment, a surgical fastener includes a pair of spaced insertion points having internally facing barbs. The internally facing barbs desirably protect the barbs from external forces, and make the surgical fasteners easier to multi-feed without damaging the barbs. These embodiments may have straight side walls and back spans that enable the surgical fasteners to remain properly aligned within a laparoscopic tube. 
     In one embodiment, surgical fasteners may incorporate active agents such anti-microbials and anti-adhesion materials. In one embodiment, surgical fasteners may incorporate radio-opacity to enable the surgical fasteners to be visible on x-ray imaging machines. 
     In one embodiment, ribs are formed on the outside of each leg of the surgical fastener, and an insertion fork has a mating channel that straddles each of the ribs. The ends of each fork tine bottom out in recesses or seating surfaces formed in the insertion tips of the surgical fastener. This above design transfers the complexity of manufacturing recesses from the legs of the surgical fastener to the tines of the insertion tool. This feature is especially important because the applicator instrument will preferably dispense multiple surgical fasteners (as opposed to just one insertion fork). 
     In one embodiment, an insertion tool includes a bridge that extends between proximal ends of fork tines. The shape of the bridge on the insertion tool may substantially conform to the proximal face of the bridge at the proximal end of the surgical fastener. In one embodiment, the insertion fork is designed so that the bridge element of the insertion fork comes into contact with the proximal end of the surgical fasteners at the time, or just prior to when, the distal ends of each fork bottoms out or engages the seating surfaces formed in the insertion tips of the surgical fastener. In one embodiment, the bridge of the insertion fork may include a softer (with respect to the durometer of the rest of the insertion fork) elastomeric material to reduce the required dimensional precision necessary to assure contact of the bridge and distal fork ends with the surgical fastener at about the same time. This configuration preferably enables the driving force behind the surgical fastener to be distributed along a greater surface area of the surgical fastener so as to reduce the pressure generated between the insertion tool and the surgical fastener. 
     These and other preferred embodiments of the invention will be described in more detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a perspective view of an applicator instrument for dispensing surgical fasteners, in accordance with one embodiment of the present invention. 
         FIG. 1B  shows a left side view of the applicator instrument shown in  FIG. 1A . 
         FIG. 1C  shows a right side view of the applicator instrument shown in  FIG. 1A . 
         FIG. 2  shows a cross sectional view of a proximal end of the applicator instrument shown in  FIGS. 1A-1C , in accordance with one embodiment of the present invention. 
         FIG. 3A  shows an exploded perspective view of a distal end of the applicator instrument shown in  FIGS. 1A-1C , in accordance with one embodiment of the present invention. 
         FIG. 3B  shows an exploded left side view of the distal end of the applicator instrument shown in  FIG. 3A . 
         FIGS. 4A-4E  show a staging leaf assembly for the applicator instrument shown in  FIGS. 1A-1C , in accordance with one embodiment of the present invention. 
         FIG. 5A  shows a perspective view of a distal end of an applicator instrument for dispensing surgical fasteners, in accordance with one embodiment of the present invention. 
         FIG. 5B  shows a side view of the distal end of the applicator instrument shown in  FIG. 5A . 
         FIG. 5C  shows a top plan view of the distal end of the applicator instrument shown in  FIGS. 5A and 5B . 
         FIG. 6  shows a perspective view of a distal end of an applicator instrument, in accordance with one embodiment of the present invention. 
         FIG. 7A  shows a distal end of an applicator instrument including an outer tube, in accordance with one embodiment of the present invention. 
         FIG. 7B  shows the distal end of the applicator instrument of  FIG. 7A  with the outer tube removed. 
         FIG. 8A  shows a perspective view of a surgical fastener, in accordance with one embodiment of the present invention. 
         FIG. 8B  shows a front view of the surgical fastener shown in  FIG. 8A . 
         FIG. 8C  shows a left side view of the surgical fastener shown in  FIG. 8A  including an insertion tip. 
         FIG. 8C-1  shows an enlarged view of the insertion tip shown in  FIG. 8C . 
         FIG. 8D  shows a right side view of the surgical fastener shown in  FIG. 8A . 
         FIG. 8E  shows a distal end view of the surgical fastener shown in  FIG. 8A . 
         FIG. 8F  shows a proximal end view of the surgical fastener shown in  FIG. 8A . 
         FIG. 8G  shows a cross-sectional view of one of the legs of the surgical fastener shown in  FIG. 8F . 
         FIG. 9A  shows a perspective view of an insertion fork aligned with a surgical fastener, in accordance with one embodiment of the present invention. 
         FIG. 9B  shows a top plan view of the insertion fork and the surgical fastener shown in  FIG. 9A . 
         FIG. 10A  shows a distal end of an applicator instrument for dispensing surgical fasteners, in accordance with one embodiment of the present invention. 
         FIG. 10B  shows a side view of the distal end of the applicator instrument shown in  FIG. 10A . 
         FIG. 10C  shows a top plan view of the distal end of the applicator instrument shown in  FIGS. 10A and 10B . 
         FIGS. 11A-11N  show a cross-sectional view of a proximal end of an applicator instrument during stages of a firing cycle, in accordance with one embodiment of the present invention. 
         FIGS. 11A-1 through 11N-1  show a cross-sectional side view of a distal end of an applicator instrument during the stages of a firing cycle shown in respective  FIGS. 11A-11N . 
         FIGS. 12A-12E  show a method of using an applicator instrument for dispensing surgical fasteners for securing a prosthetic device to tissue, in accordance with one embodiment of the present invention. 
         FIG. 13A  shows a perspective view of a lockout system for an applicator instrument, in accordance with one embodiment of the present invention. 
         FIG. 13B  shows a side view of the lockout system shown in  FIG. 13A . 
         FIGS. 14A-14E  show a top plan view of the lockout system of  FIGS. 13A and 13B , in accordance with one embodiment of the present invention. 
         FIGS. 15A-15E  show other perspective views of the lockout system shown in  FIGS. 13A-13B and 14A-14E , in accordance with one embodiment of the present invention. 
         FIGS. 16A-16B  show a surgical fastener, in accordance with one embodiment of the present invention. 
         FIGS. 17A-17C  show a method of dispensing a surgical fastener using an insertion tool, in accordance with one embodiment of the present invention. 
         FIGS. 18A-18B  show a surgical fastener, in accordance with one embodiment of the present invention. 
         FIGS. 19A-19C  show a distal end of an insertion tool for implanting the surgical fastener of  FIGS. 18A-18B , in accordance with one embodiment of the present invention. 
         FIGS. 20A-20C  show a method of implanting the surgical fastener of  FIGS. 18A-18B  using the insertion tool of  FIGS. 19A-19C , in accordance with one embodiment of the present invention. 
         FIG. 20B-1  shows an expanded view of the surgical fastener and the distal end of the insertion tool shown in  FIG. 20B . 
         FIGS. 21A-21B  show a surgical fastener, in accordance with one embodiment of the present invention. 
         FIGS. 22A-22C  show an insertion tool for implanting the surgical fastener of  FIGS. 21A-21B , in accordance with one embodiment of the present invention. 
         FIG. 23  shows a perspective view of a surgical fastener having out of plane barbs, in accordance with one embodiment of the present invention. 
         FIG. 24  shows a surgical fastener, in accordance with one embodiment of the present invention. 
         FIG. 25A  shows a perspective view of a surgical fastener, in accordance with one embodiment of the present invention. 
         FIG. 25B  shows an insertion tool for deploying the surgical fastener of  FIG. 25A , in accordance with one embodiment of the present invention. 
         FIG. 26  shows a front view of a surgical fastener, in accordance with one embodiment of the present invention. 
         FIG. 27  shows a distal end of an applicator instrument for dispensing surgical fasteners, in accordance with one embodiment of the present invention. 
         FIGS. 28A and 28B  show a method of using the applicator instrument shown in  FIG. 27  for dispensing a surgical fastener, in accordance with one embodiment. 
         FIG. 29  shows a distal end of an applicator instrument for dispensing surgical fasteners, in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1A-1C , in one embodiment, an applicator instrument  100  for dispensing surgical fasteners has a proximal end  102  and a distal end  104 . The applicator instrument  100  includes a housing  106  that contains a firing system for deploying the surgical fasteners. The housing  106  has a left cover  108  and a right cover  110 . The left and right covers  108 ,  110  have lower ends forming a hand grip  112 . The applicator instrument  100  preferably includes a trigger  114  that may be squeezed for dispensing the surgical fasteners from the distal end  104  of the instrument. In one embodiment, the applicator instrument  100  holds a plurality of surgical fasteners, whereby a single surgical fastener is dispensed from the distal end  104  of the applicator instrument each time the trigger  114  is squeezed. In one embodiment, the applicator instrument holds a plurality of surgical fasteners that are advanced toward the distal end of the outer tube  116  each time the trigger  114  is squeezed. The surgical fasteners preferably advance one position each time the trigger is squeezed. 
     In one embodiment, the applicator instrument  100  desirably includes an elongated outer shaft or tube  116  having a proximal end  118  coupled with a distal end of the housing  106  and a distal end  120  adapted to dispense the surgical fasteners. The distal-most end of the elongated outer tube  116  preferably has an end cap  122  secured thereto. The applicator instrument preferably has a longitudinal axis designated A-A that extends between the proximal and distal ends  102 ,  104  thereof. The outer tube  116  desirably extends along the longitudinal axis A-A. 
     Referring to  FIG. 1A , in one embodiment, the housing  106  may include a lockout indicator opening  124  that provides visual access to a lockout indicator. In one embodiment, the applicator instrument initially holds a plurality of surgical fasteners that are dispensed from the distal end  120  of the outer tube  116 . The lockout indicator preferably moves toward a lockout condition that occurs after all of the surgical fasteners have been dispensed. The lockout indicator opening  124  may provide an indication of how many surgical fasteners have been dispensed, how many surgical fasteners remain in the applicator instrument, and/or when the lockout condition is reached. 
     Referring to  FIG. 2 , in one embodiment, the housing  106  preferably contains a firing system for dispensing one or more surgical fasteners from the distal end of the instrument. As will be described in more detail below, many of the components of the firing system move along the longitudinal axis A-A, between the proximal and distal ends of the instrument. The components generally move toward the distal end  104  as the trigger  114  is pulled or squeezed and reverse direction to move toward the proximal end as the trigger opens. 
     In  FIG. 2 , the left cover  108  ( FIG. 1A ) of the housing  106  has been removed to reveal at least some of the components of the firing system. In one embodiment, the firing system includes the trigger  114  having a trigger gear  126  coupled therewith. The trigger gear  126  preferably includes a trigger return projection  128  adapted to travel within a trigger guide path  129 . The trigger return projection  128  is desirably coupled with an upper end of a trigger return spring  130 . In one embodiment, the trigger return spring  130  is stretched as the trigger  114  is squeezed for storing energy in the trigger return spring. When the trigger is free to return to the open position, the trigger return spring  130  preferably pulls the trigger return projection  128  toward the initial position shown in  FIG. 2 . The firing system preferably includes a trigger dampening element  132  coupled with the trigger return projection  128  for dampening movement of the trigger  114  as it approaches the ends of the trigger guide path  129 . The trigger dampening element  132  may be made of a compliant material such as a polymer or rubber. 
     The trigger gear  126  includes trigger gear teeth  134  adapted to engage a first set of teeth (not shown) provided on a drive gear  136 . The drive gear  136  includes a second set of teeth  138  adapted to mesh with teeth  140  providing on an underside of a yoke  142 . The drive gear  136  is driven by the trigger gear  126 , As the trigger  114  is squeezed, the trigger gear  126  rotates the drive gear  136  in a counter clockwise direction, As the trigger  114  opens, the trigger gear  126  rotates the drive gear  136  in a clockwise direction. 
     In one embodiment, the firing system includes a yoke  142  that is adapted to move distally and proximally along the longitudinal axis A-A of the applicator instrument. In one embodiment, the yoke  142  is directly coupled to the trigger  114  through the trigger gear  126  and the drive gear  136 , As the trigger  114  is squeezed to the closed trigger position, the trigger gear  126  and the drive gear  136  move the yoke  142  distally (to the left in  FIG. 2 ). As the trigger  114  returns to the open trigger position, the trigger gear  126  and the drive gear  136  move the yoke  142  proximally (to the right in  FIG. 2 ). 
     In one embodiment, the firing system preferably includes a ratchet pawl  144  having a ratchet pawl projection  145  that engages teeth on an underside of the yoke  142 . The ratchet pawl is desirably coupled with a ratchet pawl torsion spring  146 . As will be described in more detail below, during at least one stage of a firing cycle, the ratchet pawl  144  constrains the yoke  142  from changing direction until the trigger  114  is completely closed or completely open. In one embodiment, as the trigger  114  is pulled, the yoke  142  is required to move distally beyond the projection  145  on the ratchet pawl  144  before the yoke is able to change directions and move proximally. 
     The firing system preferably includes a primary latch  150  that projects from a distal end of the yoke  142 . The primary latch  150  is connected to the yoke  142  and moves simultaneously in distal and proximal directions with the yoke. In one embodiment, the primary latch  150  is adapted to move around a primary latch racetrack  152  formed in the housing  106  for systematically coupling and de-coupling the yoke  142  from another component of the firing system, as will be described in more detail below. In one embodiment, as the yoke  142  moves distally, the primary latch  150  preferably moves over the primary latch racetrack  152 . As the yoke  142  moves proximally, the primary latch  150  preferably moves under the primary latch racetrack  152 . 
     The firing system preferably includes an indexer  154  that is adapted to move in distal and proximal directions along the longitudinal axis A-A of the applicator instrument. The indexer  154  includes a lower slot  156  that is in communication with a boss  158  extending from a side of the yoke  142 , hereinafter referred to as the yoke boss  158 . The yoke boss  158  is adapted to slide within the lower slot  156  of the indexer  154 . In one embodiment, when the yoke boss  158  reaches a distal end  160  of the lower slot  156  of the indexer, the yoke boss  158  urges the indexer  154  to move toward the distal end of the applicator instrument  100 . The indexer  154  includes an upper slot  162  coupled with a lockout indicator system, as will be described in more detail below. 
     In one embodiment, the indexer  154  is directly coupled to an advancer  166  that is adapted to advance surgical fasteners toward the distal end of the applicator instrument. As the indexer  154  moves distally, the advancer  166  moves simultaneously with the indexer toward the distal end of the applicator instrument. As the indexer moves proximally, the advancer  166  moves simultaneously with the indexer toward the proximal end of the applicator instrument. In one embodiment, the advancer  166  is adapted to move the surgical fasteners toward the distal end of the applicator instrument so that the surgical fasteners may be dispensed from the distal end of the instrument. In one embodiment, the surgical fasteners are advanced one position each time the advancer moves proximally. 
     In one embodiment, the firing system desirably includes a spring block  170  that is selectively coupled with the yoke  142  through the primary latch  150 . The spring block is preferably adapted to move distally and proximally along the longitudinal axis designated A-A. In one embodiment, when the primary latch  150  is coupled with the spring block, the yoke and the spring block preferably move simultaneously with one another as a unit. When the primary latch  150  is de-coupled from the spring block  170 , the yoke  142  and the spring block preferably move independently of one another. 
     In one embodiment, the firing system also preferably includes a firing spring  172  disposed within the spring block  170 . The firing spring  172 , which is pre-compressed within the spring block, desirably has a distal end coupled with a firing rod  174  and a proximal end that engages a proximal end wall  171  of the spring block. In one embodiment, the proximal end of the firing rod  174  desirably has a cruciform-shaped coupling  176  that is connected with the distal end of the firing spring  172 . One or more firing rod dampers  178  may be connected with the cruciform-shaped coupling  176  for dampening movement of the firing rod  174  as it reaches the distal and/or proximal ends of its travel path. 
     In one embodiment, the firing system includes a firing spring release latch  180  that constrains distal movement of the firing rod. During one stage of a firing cycle, the firing spring release latch constrains the firing rod from distal movement as energy is stored in the firing spring  172 . During a later stage of the firing cycle, the firing spring release latch releases the firing rod  174  for distal movement. As will be described in more detail below, in one embodiment, the firing latch  180  preferably engages an outer surface of the spring block  170 . The outer surface of the spring block preferably urges the firing latch into a release position so as to release the firing rod  174  for distal movement. 
     in one embodiment, the firing system desirably includes a firing rod return spring  184  that engages the spring block  170  for returning the spring block  170  to the initial, proximal position shown in  FIG. 2 . As the spring block  170  moves distally (to the left), energy is stored in the firing rod return spring  184 . The energy is later released for moving the spring block proximally. At this stage, the firing rod may move proximally with the spring block. The firing system also desirably includes one or more dampening springs  186  that are adapted to engage one or more components of the firing system for dampening movement of the components toward the ends of travel ranges. The dampening springs preferably minimize noise, vibration, violent movements, etc. during firing cycles. 
     Referring to  FIG. 3A , in one embodiment, a distal end  104  of the applicator instrument  100  is adapted to deliver surgical fasteners  232 . The outer tube ( FIG. 1A ) that normally surrounds the components shown in  FIG. 3A  has been removed to more clearly show the internal components. In the particular embodiment shown in  FIG. 3A , the internal components at the distal end  104  of the applicator instrument  100  have been exploded for more dearly showing the parts and the operation of the applicator instrument. 
     Referring to  FIG. 3A , in one embodiment, the applicator instrument  100  includes a ceiling stamping  200  having one or more ceiling stamping spring tabs  202  provided along the length thereof. The ceiling stamping  200  preferably includes one or more ceiling stamping assembly notches  204  formed in side walls thereof for facilitating assembly of the applicator instrument. The ceiling stamping  200  preferably includes a pair of opposed alignment guides  206  that are adapted to guide distal and proximal movement of the firing rod, as will be described in more detail below. 
     The applicator instrument also preferably includes an anti-backup stamping  208  that is assembled with the ceiling stamping  200 . The anti-backup stamping  208  includes side walls having assembly tabs  210  projecting therefrom. The assembly tabs  210  are adapted to be aligned with the assembly grooves  204  on the ceiling stamping  200  to facilitate proper alignment and assembly of the ceiling stamping with the anti-backup stamping. The anti-backup stamping  208  desirably includes anti-backup tabs  212  provided along the length thereof. The anti-backup tabs preferably project toward the distal end of the applicator instrument and allow the surgical fasteners to move in only one direction, namely distally. The anti-backup tabs  212  desirably constrain the surgical fasteners from moving toward the proximal end of the applicator instrument. 
     Referring to  FIG. 3A , the anti-backup stamping  208  preferably includes a staging leaf opening  214  provided adjacent a distal end of the anti-backup stamping  208 , and an aperture  216  proximal the staging leaf opening  214  that is desirably used for securing a staging leaf assembly to the anti-backup stamping  208 , as will be described in more detail below. 
     The applicator instrument preferably includes the firing rod  174  having an insertion fork  220  at a distal end thereof. The insertion fork  220  has a proximal end  222  coupled with a distal end of the main section of the firing rod  174 , and a distal end  224  adapted to engage the surgical fasteners. The distal end of the application instrument also preferably includes the staging leaf assembly including a staging leaf support  226  and a staging leaf  228 . Proximal ends of the respective staging leaf support  226  and the staging leaf  228  are aligned with the aperture  216  in the anti-backup stamping  208 . 
     The applicator instrument also preferably includes the advancer  166 , which is adapted to advance surgical fasteners toward the distal end of the instrument. The advancer desirably has advancer tabs  230  adapted to engage the surgical fasteners for urging the surgical fasteners toward the distal end of the application instrument. In one embodiment, the advancer  166  advances the surgical fastener one position toward the distal end of the applicator instrument each time the trigger is squeezed closed. 
       FIG. 3B  shows an exploded side view of the distal end  104  of the applicator instrument  100 . The ceiling stamping  200  is adapted for assembly with the opposed anti-backup stamping  208 . The assembly grooves  204  on the ceiling stamping  200  are preferably aligned with the assembly tabs  210  on the anti-backup stamping  208 . The firing rod  174  including the insertion fork  220 , the advancer  166 , the staging leaf support  226  and the staging leaf spring  228  are preferably at least partially disposed between the ceiling stamping  200  and the anti-backup stamping  208 . After the components shown in  FIG. 3B  have been assembled together, the components are desirably disposed within the outer tube  116  shown in  FIGS. 1A-1C . In one embodiment, the end cap  122  is desirably assembled with distal-most ends of the outer tube  116 , the ceiling stamping  200 , and the anti-backup stamping  208 . In one embodiment, the ceiling stamping spring tabs  202  preferably press against the inner surface of the outer tube for minimizing movement of the internal components within the outer tube. 
     Referring to  FIG. 3B , in one embodiment, the advancer  166  includes a series of advancer tabs  230  projecting from an underside of the advancer. The advancer tabs  230  preferably project toward the distal end of the advancer  166 . The advancer tabs  230  desirably engage surgical fasteners  232  disposed within the outer tube for urging the surgical fasteners toward the distal end of the applicator instrument. In one embodiment, a plurality of surgical fasteners  232 A- 232 D are desirably provided within the applicator instrument. Each time the trigger is squeezed, the advancer tabs  230  urge the surgical fasteners  232 A- 232 D toward the distal end of the instrument for being dispensed from the distal end of the instrument. When a trailing surgical fastener (e.g., the fastener designated  232 B) is advanced sufficiently to become a lead surgical fastener (e.g., the lead fastener designated  232 A), it is advanced into contact with the staging leaf  228 , which is adapted to move the lead surgical fastener  232 A into alignment with tines at the distal end of the insertion fork  220 . 
     Referring to  FIGS. 4A-4E , in one embodiment, the applicator instrument includes the staging leaf assembly located adjacent the distal end of the anti-backup stamping  208 . Referring to  FIG. 4A , in one embodiment, the anti-backup stamping  208  includes the anti-backup tabs  212  projecting toward the distal end of the anti-backup stamping  208 . The anti-backup stamping  208  includes the staging leaf opening  214  preferably disposed between the final anti-backup tab  212 A and the distal end of the anti-backup stamping  208 . The anti-backup stamping  208  also preferably includes the opening  216  proximal the staging leaf opening  214 . The aperture is preferably adapted to be aligned with a proximal end of the staging leaf support  226  and the staging leaf  228 . 
     Referring to  FIG. 4A , as noted above, the staging leaf assembly preferably includes the staging leaf support  226  and the staging leaf  228 . The staging leaf support  226  has an opening  227  at a proximal end thereof that is desirably aligned with the opening  216  in the anti-backup stamping  208 . The staging leaf  228  desirably includes a distal end having a staging leaf tab  229  and a proximal end including an opening  231  that is adapted to be aligned with the opening  216  in the anti-backup stamping and the opening  227  in the staging leaf support. The staging leaf  228  also includes a staging leaf anti-backup tab  233  projecting toward the distal end of the staging leaf  228 . 
       FIGS. 4B-4E  show how the staging leaf support  226  and the staging leaf  228  are assembled with the anti-backup stamping  208 . As shown in  FIGS. 4B and 4C , in one embodiment, the staging leaf  228  is positioned over the staging leaf support  226  and the proximal ends of the assembled components are passed through the staging leaf opening  214  so that the openings  227 ,  231  at the proximal ends of the staging leaf support  226  and the staging leaf  228  are aligned with the opening  216  in the anti-backup stamping  208 . 
     Referring to  FIGS. 4D and 4E , the proximal ends of the staging leaf  228  and the staging leaf support  226  underlie a bottom surface of the anti-backup stamping  208 , and are preferably permanently connected to the underside surface of the anti-backup stamping. The connection may be made using a fastener, such as a screw, or other well-known connecting methods such as welding. As shown in  FIGS. 4D and 4E , the distal ends of the staging leaf  228  and the staging leaf support  226  extend through the staging leaf opening  214 , with the staging leaf tab  229  normally projecting above the anti-backup stamping  208 . 
     Although the present invention is not limited by any particular theory of operation, it is believed that the staging leaf assembly provides a spring-like device at the distal end of the anti-backup stamping for urging and/or moving a lead surgical fastener into alignment with the tines at the distal end of the insertion fork. The staging leaf assembly may be deflected downwardly by the distal ends of the advancer and the insertion fork when those components are extended toward the distal end of the applicator instrument. When the insertion fork and the advancer are retracted proximal to the staging leaf assembly, however, the staging leaf assembly desirably springs upwardly to the position shown in  FIGS. 4B-4E . As the staging leaf assembly springs upwardly, a lead surgical fastener positioned atop the staging leaf assembly is moved into alignment with the distal end of the insertion fork. In one embodiment, the staging leaf tab  229  and the staging leaf anti-backup tab  233  stabilize the lead surgical fastener and hold the lead surgical fastener in place as the insertion fork is advanced to secure the lead surgical fastener. 
     Referring to  FIGS. 5A-5C , in one embodiment, the ceiling stamping  200  is assembled with the anti-backup stamping  208 . The ceiling stamping  200  includes at least one assembly groove  204  that is aligned with at least one assembly tab  210  on the anti-backup stamping  208  for ensuring proper alignment of the stampings  200 ,  208  with one another. The distal-most ends of the ceiling stamping  200  and the anti-backup stamping  208  are preferably held together by the end cap  122 . In one embodiment, the ceiling stamping has ceiling stamping spring tabs  202  that preferably engage an inner surface of the outer tube (not shown) for enhancing the stability of the applicator instrument and preventing the ceiling stamping and the anti-backup stamping from moving relative to the outer tube. In one embodiment, the end cap  122 , and the distal-most ends of the ceiling stamping and the anti-backup stamping have one or more tongue and groove structures for assembling the end cap  122  with the ceiling and anti-backup stampings  200 ,  208 . 
     Referring to  FIG. 6 , in one embodiment, distal-most ends of the ceiling stamping  200  and the anti-backup stamping  208  are held together by the end cap  122 . In one embodiment, the ceiling stamping  200  may include a pair of guide flanges  206  that preferably conform to the side walls of the insertion fork  220  as the firing rod moves distally and proximally. In one embodiment, the guide flanges  206  preferably guide the distal and proximal movement of the insertion fork  220  to ensure proper alignment of the tines of the insertion fork with the lead surgical fastener  232 A. The applicator instrument  100  desirably includes the staging leaf assembly including the staging leaf support  226  and the staging leaf  228 . As noted above, proximal ends of the staging leaf support  226  and the staging leaf  228  are desirably coupled with the anti-backup stamping  208 . In one embodiment, the advancer  166  is desirably positioned between the staging leaf assembly and the insertion fork  220 . The advancer  166  includes advancer tabs  230  that engage the surgical fasteners  232  for advancing the surgical fasteners toward the distal end  104  of the applicator instrument  100 . Each time the advancer moves distally, the advancer tabs preferably advance the surgical fasteners one position toward the distal end of the applicator instrument. 
     Referring to  FIG. 7A , in one embodiment, the outer tube  116  is disposed around the ceiling stamping  200  and the anti-backup stamping  208 . In  FIG. 7A , the outer tube  116  is transparent so that the ceiling stamping and the anti-backup stamping are visible. The end cap  122  is secured over the distal end of the outer tube  116  and includes assembly flanges that are disposed between the outer tube  116 , and the ceiling stamping and anti-backup stamping. The end cap  122  preferably engages the ceiling stamping  200  and the anti-backup stamping  208  so as to provide stability at the distal end of the applicator instrument  100 . In one embodiment, the end cap  122  preferably includes castling  242  formed in a distal end face thereof. The castling  242  is adapted to engage surfaces (e.g., mesh) so as to prevent the distal end of the applicator instrument from sliding or moving relative to the opposing surfaces. The castling  242  may also be used for aligning the distal end of the applicator instrument with a prosthetic device, such as a prosthetic mesh. In one embodiment, the castling may be used to align the distal end of the applicator instrument with one or more strands on a prosthetic device. 
       FIG. 7B  shows the distal end of the applicator instrument of  FIG. 7A  with the outer tube  240  removed. The end cap  122  includes a top assembly flange  244  that engages the ceiling stamping  200  and a bottom assembly flange  246  that engages the anti-backup stamping  208 . The top and bottom assembly flanges  244 ,  246  preferably hold the distal-most ends of the ceiling stamping and the anti-backup stamping together for stabilizing the distal end of the applicator instrument. The inner face of the end cap  122  preferably includes a pair of side assembly tabs  248 A,  248 B that are disposed between the ceiling stamping and the anti-backup stamping. The side assembly tabs  248 A,  248 B may also enhance stability of the distal end of the applicator instrument. 
     Referring to  FIGS. 8A-8F , in one embodiment, the applicator instrument dispenses surgical fasteners from a distal end thereof, Referring to  FIGS. 8A and 8B , in one embodiment, a surgical fastener  232  desirably includes a distal end  250  and a proximal end  252 . The surgical fastener  232  preferably includes a first leg  254  having a first tip  256  provided at a distal end of the first leg, and a second leg  258  having a second tip  260  provided at a distal end of the second leg. In one embodiment, the cross-sectional dimension of each first and second leg diminishes when moving from the proximal ends toward the distal ends of the legs. The surgical fastener  232  preferably includes a bridge  262  adjacent the proximal end  252  of the surgical fastener that connects the proximal ends of the first and second legs  254 ,  258 . In one embodiment, the bridge may be positioned between the proximal and distal ends of the surgical fastener so long as it interconnects the first and second legs. The surgical fastener  232  preferably includes at least one first barb  264  projecting rearwardly from the first tip  256  and at least one second barb  266  projecting rearwardly from the second tip  260 . Although only one barb is shown on each leg, other surgical fasteners may have multiple barbs on each leg or tip. The first and second tips  256 ,  260  may be conical in shape. The respective tips may be formed with sharp leading points or may be more obtuse. 
     In one embodiment, the first and second tips  256 ,  260  have skewed distal piercing tips or insertion tips that are skewed with respect to longitudinal axes of the respective first and second legs  254 ,  258 . In one embodiment, the distal piercing tips are skewed outwardly with respect to the longitudinal axes of the first and second legs. In one embodiment, the distance between the tips is greater than the distance between the legs for increasing the likelihood of fibers of a prosthetic device being captured between the legs. In one embodiment, the first and second tips  256 ,  260  have blunt distal piercing points. The blunt points enable the surgical fastener to penetrate tissue while minimizing unwanted penetration into the hand of an operator. 
     Referring to  FIG. 8B , in one embodiment, the bridge  262  preferably includes a concave inner surface  268  facing toward the distal end  250  of the surgical fastener  232  and a convex outer surface  270  facing toward the proximal end  252  of the surgical fastener. The first leg  254  has an outer wall having a first rib  272  that extends along a longitudinal axis A 1  of the first leg. The second leg  258  includes an outer wall having a second rib  274  that extends along the longitudinal axis A 2  of the second leg. In one embodiment, the distance D 1  between the piercing points at the distal ends of the first and second tips  256 ,  260  is preferably greater than the distance D 2  between the opposing surfaces of the first and second legs  254 ,  256 . The wider relative distance between the distal piercing points of the first and second tips  256 ,  260  preferably ensures that the surgical fastener will engage strands on a porous prosthetic device, such as the strands of a surgical mesh. In one embodiment, the outwardly skewed distal piercing tips provides increased capacity to capture surgical mesh fibers where the mesh fibers are separated from one another without the need to increase the span between each leg. 
     Referring to  FIG. 8C , in one embodiment, the first leg  254  has the first rib  272  extending along the longitudinal axis A 1  of the first leg. When viewed from the side as shown in  FIG. 8C , the first rib  272  is preferably in substantial alignment with a distal point of the first piercing tip  256 . 
       FIG. 8C-1  shows an enlarged view of the first piercing or insertion tip  256  including a blunt piercing point  257 . In one embodiment, the blunt piercing point  257  enables the distal end of the surgical fastener to penetrate tissue while minimizing unwanted penetration into the hand of an operator. 
     Referring to  FIG. 8D , in one embodiment, the second leg  258  has the second rib  274  extending along the longitudinal axis A 2  of the second leg  258 . When viewed from the side as shown in  FIG. 8D , the second rib  274  is preferably aligned with a distal point of the second tip  260 . 
     Referring to  FIG. 8E , in one embodiment, the first and second piercing tips  256 ,  260  are preferably skewed outwardly from a center of the surgical fastener  232 . In one embodiment, the first and second piercing tips  256 ,  260  are preferably asymmetrical and are configured to extend outwardly from the center of the surgical fastener  232 . 
     Referring to  FIG. 8F , in one embodiment, the rear face of the first insertion tip  256  includes a first seating surface  280  adapted to receive a distal end of a first tine of an insertion fork. The rear face of the second tip  260  preferably includes a second seating surface  282  adapted to receive a distal end of a second tine of the insertion fork. In one embodiment, the convex seating surfaces  280 ,  282  are preferably substantially aligned with the distal piercing points of the first and second piercing tips  256 ,  260 . The distal ends of the tines of the insertion fork may have surfaces that conform to the respective seating surfaces  280 ,  282 . 
     Referring to  FIG. 8G , in one embodiment, the first leg  254  has an inner face that is rounded and an outer face that is squared-off. Although the present invention is not limited by any particular theory of operation, it is believed that such a structure desirably increases the strength of the surgical fastener by increasing the section modulus. Providing legs having a cross-section with an inner rounded-off surface and an outer squared-off surface also preferably increases the force required to pull the surgical fastener out of tissue. 
     In one embodiment, the surgical fastener may be made of absorbable and/or non-absorbable materials. Preferred absorbable materials include PDS, PDS/lactide-glycolide blends, PLA, etc. In one embodiment, each surgical fastener is sized to fit inside of a 5 mm outer diameter tube (typically trocar cannula dimension). The surgical fastener is fabricated by molding, however, with small modifications, other processes such as casting, stamping, and machining may be used. In one embodiment, the surgical fasteners may be extruded into a general shape, and then formed. 
     Referring to  FIGS. 9A and 9B , in one embodiment, the surgical fastener  232  is aligned with the insertion fork  220  at the distal end of the firing rod for being dispensed from the distal end of the applicator instrument. The insertion fork  220  includes a proximal end  222  adapted for connection with a distal end of a main section of a firing rod (not shown) and a distal end  224  adapted to engage one or more surfaces of the surgical fastener  232 . In one embodiment, the distal end  224  of the insertion fork  220  includes a first tine  290  having a first inner groove  292  formed therein, and a second tine  294  having a second inner groove  296  formed therein. In one embodiment, the inner grooves  292 ,  296  preferably oppose one another and extend along axes that are parallel with the longitudinal axis A-A of the applicator instrument. In operation, the opposing inner grooves  292 ,  296  of the first and second tines  290 ,  294  are preferably adapted to slide over the ribs  272 ,  274  on the first and second legs  254 ,  258  of the surgical fastener. The engagement of the inner grooves  292 ,  296  with the ribs  272 ,  274  preferably aligns the surgical fastener element  232  with the distal end  224  of the insertion fork  220 , and stabilizes the surgical fastener during implantation in tissue. In one embodiment, the distal-most tips of the first and second tines  290 ,  294  are advanced until they abut against the convex seating surfaces  280 ,  282  provided at the distal surfaces of the first and second tips  256 ,  260 . 
     Although the present invention is not limited by any particular theory of operation, it is believed that providing an insertion fork with grooved tines that engage ribs on outer surfaces of the legs of a surgical fastener will enhance stability and control of the surgical fastener when dispensing the surgical fastener from the distal end of the applicator instrument. In addition, the insertion force is provided closer to the distal end of the surgical fastener and not only at the proximal end of the surgical fastener as is the case with prior art systems. This feature (i.e., providing insertion force on the surgical fastener near the distal end of the fastener) may enable smaller and/or lower profile surgical fasteners to be used. 
     Referring to  FIG. 10A , in one embodiment, the staging leaf assembly includes a staging leaf support  226  and a staging leaf  228  adapted to lift a lead surgical fastener  232 A into alignment with the tines at the distal end  224  of the insertion fork  220 . The staging leaf  228  preferably includes a staging leaf tab  229  that may engage the inner surface of the bridge  262  of the surgical fastener  232 . The ribs on the legs of the surgical fastener are preferably aligned with the opposing inner grooves  292 ,  296  on the opposing tines  290 ,  294  of the insertion fork  220 . 
     Referring to  FIG. 10B , in one embodiment, the staging leaf  228  aligns the ribs  272 ,  274  on the surgical fastener  232  with the inner grooves on the tines  290 ,  294  of the insertion fork  220 . The staging leaf tab  229  preferably engages the bridge  262  of the surgical fastener  232  for stabilizing the surgical fastener  232  as the tines  290 ,  294  slide over the ribs  272 ,  274 . 
       FIG. 10C  shows a top plan view of the applicator instrument with the inner groove  292  of the first tine  290  aligned with the first rib  272  on the first leg  254  of the surgical fastener  232  and the inner groove  296  on the second tine  294  aligned with the second rib  274  on the second leg  258  of the surgical fastener. As the surgical fastener is held stationary by the staging leaf  228 , the firing rod including the insertion fork  220  is advanced toward the surgical fastener until the distal-most ends of the tines  290 ,  294  are seated against the convex seating surfaces located behind the first and second tips  256 ,  260 . After the tines  290 ,  294  are seated against the convex seating surfaces, the insertion fork  220  is ready for further advancement toward the distal end of the applicator instrument for dispensing the surgical fastener  232  from the applicator instrument. 
       FIGS. 11A-11N  show the firing system of the applicator instrument during various stages of a firing cycle.  FIGS. 11A-1 through 11N-1  show the distal end of the applicator instrument during the same stages shown in respective  FIGS. 11A-11N . For example,  FIG. 11A  shows the firing system at the start of a firing cycle with the trigger  114  fully open and the firing rod  174  fully retracted.  FIG. 11A-1  shows the distal end of the applicator instrument at the same stage as shown in  FIG. 11A .  FIGS. 11B-11N  and  FIGS. 11B-1 through 11N-1  follow the same pattern. 
     Referring to  FIG. 11A , in one embodiment, in a first stage of a firing cycle, the trigger  114  is completely open and the trigger gear projection  128  is at the lower end of the trigger guide  129 . The yoke  142 , the indexer  154 , the advancer  166 , the spring block  170 , and the firing rod  174  are all fully retracted toward the proximal end of the applicator instrument. At the first stage of the firing cycle shown in  FIG. 11A , the primary latch  150  is in a neutral position and is de-coupled from the spring block  170 . The firing spring  172  is disposed between a proximal end of the spring block  170  and the cruciform-shaped coupling  176  at the proximal end of the firing rod  174 . The firing spring  172  extending between the spring block  170  and the firing rod  174  is desirably pre-compressed so that there is an initial distal force (to the left) on the firing rod  174 . The firing rod  174  and the advancer  166  project from a distal end of the housing  106  and extend toward a distal end of the applicator instrument  100 . 
       FIG. 11A-1  shows the distal end  104  of the applicator instrument  100  at the first stage of the firing cycle shown in  FIG. 11A . The outer tube, the ceiling stamping, and the anti-backup stamping have been removed from the drawing figure to more clearly show the other internal components disposed at the distal end of the applicator instrument. Referring to  FIG. 11A-1 , the staging leaf support  226  and the staging leaf  228  desirably hold the lead surgical fastener  232 A so that the ribs  272 ,  274  on the outer side walls of the surgical fastener are in alignment with the inner grooves formed in the times  290 ,  294  at the distal end  224  of the insertion fork  220 . The staging leaf tab  229  preferably stabilizes the lead surgical fastener  232 A from further distal movement. Additional trailing surgical fasteners  232 B,  232 C,  232 D are positioned behind the lead surgical fastener  232 A. Although only four surgical fasteners  232 A- 232 D are shown in  FIG. 10A-1 , the applicator instrument may carry additional surgical fasteners such as 10, 25, 100 or more surgical fasteners. The advancer  166  includes advancer tabs  230  that are adapted to push the respective surgical fasteners  232 B- 232 D toward the staging leaf assembly at the distal end  104  of the applicator instrument  100 . Each time the advancer  166  moves to the left, the surgical fasteners are advanced one position toward the distal end  104  of the applicator instrument  100 . 
       FIG. 11B  shows a later stage of the firing cycle during which the tines at the distal end of the insertion fork are piloted into engagement with the ribs on the legs of the lead surgical fastener. During this stage of the firing cycle, the trigger  114  is partially squeezed toward the grip  112  for moving the trigger gear  126  and the trigger gear projection  128  toward the upper end of the trigger guide  129 . As the trigger  114  is pulled, the trigger return spring  130  connected to the trigger gear projection  128  is stretched to store potential energy in the spring. As the trigger gear  126  pivots in an upward, counterclockwise direction, the teeth on the trigger gear  126  rotate the drive gear  136  in a counterclockwise direction. The second set of gear teeth  138  on the outer periphery of the drive gear  136  engage the teeth  140  extending along the bottom surface of the yoke  142  for moving the yoke  142  toward the distal end of the applicator instrument (to the left). As the yoke  142  moves toward the distal end of the applicator instrument, the primary latch  150  slides over a top surface of the primary latch raceway  152  for coupling the yoke with the spring block. Because the firing spring  172  is pre-compressed inside the spring block, the firing rod moves distally as the yoke, the spring block and the firing rod move distally as a unit. At this stage, the firing rod moves distally at a rate that is proportional to movement of the trigger. 
     Referring to  FIG. 11B , the yoke  142  is adapted to slide within the housing  106  in distal and proximal directions along the longitudinal axis of the applicator instrument designated A-A. As the yoke  142  moves distally, the yoke boss  158  slides in a distal direction toward the distal end  160  of the lower slot  156  of the indexer  154 . As will be described in more detail below, when the yoke boss  158  abuts against the distal end  160  of the lower slot  156  of the indexer  154 , the yoke boss  158  will urge the indexer  154  to move distally. 
       FIG. 11B-1  shows the distal end  104  of the applicator instrument  100  during the stage of the firing cycle shown in  FIG. 11B . The prongs  290 ,  294  at the distal end  224  of the insertion fork  220  are piloted into engagement with the legs of the lead surgical fastener  232 A. The insertion fork  220  preferably moves distally at a rate that is proportional to the rate of the trigger squeeze. The staging leaf tab  229  and the staging leaf  228  preferably stabilize the lead surgical fastener  232 A as the fork tines  290 ,  294  are piloted into engagement with the ribs of the lead surgical fastener. The staging leaf tab  229  may engage the inner surface of the outer tube to provide stability. 
       FIG. 11C  shows the firing system after the insertion fork has been piloted onto the legs of the surgical fastener. In  FIG. 11C , the distal end of the firing system is to the right and the proximal end of the firing system is to the left. At about the same time or after the insertion fork has been piloted distally for engaging the lead surgical fastener, a firing spring latch  180  engages the cruciform-shaped end  176  of the firing rod  174 . Upon the engagement, the firing spring latch  180  prevents further distal movement of the firing rod  174 . Up to this point in time, the firing rod has moved as a unit with the spring block  170 , due to the pre-load on the firing spring within the spring block. Once the firing spring latch  180  engages the cruciform-shaped end  176 , the firing rod cannot continue to move distally. As a user continues to squeeze the trigger  114 , the firing rod  174  cannot move further distally and the firing spring is compressed. 
       FIG. 11C-1  shows the distal end  104  of the applicator instrument  100  during the stage shown in  FIG. 11C . After the distal end of the insertion fork  220  has been advanced into contact with the lead surgical fastener  232 A, the firing spring latch  180  holds the firing rod  174  from further distal movement. Thus, after the distal end of the insertion fork has been piloted into contact with the lead surgical fastener, and until the applicator instrument “fires” the surgical fastener from the distal end, the firing rod does not have any further distal movement as the trigger continues to be pulled toward the fully closed position for storing potential energy in the firing spring. 
       FIG. 11D  shows a top cross-sectional view of a portion of the firing system during the same stage of the firing cycle shown in  FIG. 11C . The firing system includes the firing rod  174 , the cruciform-shaped structure  176  at the proximal end of the firing rod  174 , the firing spring  172  and the spring block  170  containing the firing spring  172 . In  FIG. 11D , the distal end of the applicator instrument is to the left and the proximal end of the applicator instrument is to the right. As shown in  FIG. 11D , as the trigger is pulled, the spring block  172  is urged toward the distal end of the applicator instrument by the primary latch (not shown). Distal movement of the spring block  170  compresses the firing spring  172  between the cruciform-shaped structure  176  at the proximal end of the firing rod  174  and the proximal end of the spring block  170 . As noted above, during this stage, the firing rod  174  is constrained from further distal movement by the firing spring latch  180  engaging the cruciform-shaped structure  176  of the firing rod  174 .  FIG. 11D-1  shows the distal end  104  of the applicator instrument during the stage shown in  FIG. 11D . As noted above, although the tines of the insertion fork  220  have been piloted around the sides of the lead surgical fastener  232 A, the firing spring latch prevents further distal movement of the firing rod  174  and the insertion fork  220 . 
       FIG. 11E  shows the firing system during a later stage of the firing cycle. The user preferably continues to squeeze the trigger  114  toward the closed position. During this stage, the yoke  142  moves further distally until the yoke boss  158  engages the distal end  160  of the lower slot  156  of the indexer  154 . Once the yoke boss  158  contacts the distal end  160  of the lower slot  156 , further distal movement of the yoke  142  urges the indexer  154  in a distal direction, which, in turn, urges the advancer  166  to move distally for advancing surgical fasteners. The indexer and the advancer preferably move together as a unit. 
     As the user continues to squeeze the trigger  114 , the yoke  142  continues to move distally, taking the spring block  170  with it in a distal direction via the coupling of the primary latch  150  with the spring block  170 . The firing rod  174  continues to be held back from further distal movement by the firing rod latch ( FIG. 11D ). As the spring block  170  moves distally, additional energy is stored in the firing spring  172  disposed within the spring block. Because it has been compressed, the firing spring is shorter than its original length with its right side disposed inside the proximal end of the spring block  170 . As the spring block  170  moves distally (to the left), the spring block return spring  184  is compressed. In one embodiment, a flange extending from the spring block  170  engages the spring block return spring  184  for storing energy in the spring block return spring. 
       FIG. 11E-1  shows the distal end  104  of the applicator instrument  100  during the stage shown in  FIG. 11E . As the indexer  154  ( FIG. 11E ) is moved distally by the yoke boss  158 , the indexer  154  urges the advancer  166  to move in a distal direction, which advances the trailing surgical fasteners  232 B,  232 C and  232 D toward the distal end of the applicator instrument. There is no further distal movement of the lead surgical fastener  232 A at this stage. 
       FIG. 11F  shows a top cross-sectional view of the firing system at a later stage of the firing cycle that occurs just before the firing rod  174  is released. In one embodiment, the spring block  170  includes a firing spring release ramp  175  projecting from a surface thereof. The firing spring release ramp  175  is preferably aligned with the firing spring release latch  180 . As the spring block  170  moves toward the distal end of the applicator instrument (to the left), the ramp  175  engages the firing spring release latch  180  for de-coupling the release latch  180  from the cruciform-shaped end  176  at the proximal end of the firing rod  174 . Once the release latch is de-coupled from the cruciform-shaped end  176  of the firing rod, the firing rod  174  is free to move distally. The energy stored in the firing spring  172  is now released to the firing rod  174 . 
       FIG. 11F-1  shows the distal end  104  of the applicator instrument  100  during the stage of the firing cycle shown in  FIG. 11F . During this stage, the firing spring release latch  180  is about to be released from engagement with the cruciform-shaped end  176  of the firing rod. The advancer  166  has moved distally for advancing the trailing surgical fasteners  232 B- 232 D toward the distal end  104  of the applicator instrument  100 . 
       FIG. 11G  shows a later stage of the firing cycle during which the firing rod is released for rapidly advancing the insertion fork toward the distal end of the applicator instrument. During this stage, the firing spring release ramp  175  pushes the firing spring release latch  180  away from engagement with the cruciform-shaped structure  176 . The firing rod  174 , unconstrained from distal movement, is rapidly advanced toward the distal end of the applicator instrument by the firing spring  172 . The firing spring  172  moves the firing rod  174  distally until the firing rod dampening pad  178  engages a stop wall SW in the housing. The firing rod dampening pad  178  may be compressed slightly until the positive stop  179  on the cruciform-shaped structure  176  engages the stop wall SW for halting all further distal movement of the firing rod. Although the present invention is not limited by any particular theory of operation, it is believed that the firing rod dampening pad  176  lengthens the time period for deceleration of the firing rod  174  so as to stop the firing rod over a longer period of time. The lengthening of the deceleration period of the firing rod preferably decreases the impact force transmitted to a user, and also desirably reduces noise. 
       FIG. 11G-1  shows the distal end  104  of the applicator instrument during the stage of the firing cycle shown in  FIG. 11G . The firing rod  174  and the insertion fork  220  have been rapidly advanced distally (to the left) by the firing spring. The lead surgical fastener  232 A is shot from the distal end  104  of the applicator instrument  100  for securing a prosthetic device (e.g., a mesh) to tissue. As shown in  FIG. 11G-1 , at a distal-most position, the distal end  224  of the insertion fork  220  has advanced beyond the distal end of the end cap  122 . 
     Referring to  FIGS. 11G and 11G-1 , the engagement of the positive stop  179  with the stop wall SW ( FIG. 11G ) limits further distal movement of the insertion fork  220 . Thus, the combination of the firing rod dampening pad  178 , the positive stop  179  and the stop wall SW limit the maximum expulsion of the lead surgical fastener  232 A and the insertion fork from the applicator instrument. It has been observed that excessive expulsion of a surgical fastener and/or insertion fork from a distal end of an applicator instrument may damage a prosthetic device or injure tissue. In one embodiment, during the stage of the firing cycle shown in  FIGS. 11G and 11G-1 , the trailing surgical fasteners  232 B- 232 D do not move distally. 
     Referring to  FIG. 11H , in one embodiment, after the lead surgical fastener  232 A has been dispensed, the firing cycle is not complete, and the trigger cannot return to the fully open position shown in  FIG. 11A . In one embodiment, during this stage of the firing cycle, the trigger  114  must be further squeezed for advancing the yoke  142  further toward the distal end of the applicator instrument. In one embodiment, the ratchet pawl  144  engaging the teeth on the underside of the yoke  142  prevents the yoke  142  from changing direction to move proximally until the projection  145  on the ratchet pawl  144  clears the proximal end of the yoke  142 . If an operator stops pulling the trigger before the projection  145  on the ratchet pawl  144  clears the proximal end of the yoke  142 , the trigger  114  freezes in position and will not return to the fully open position. Thus, an operator must continue to pull the trigger, which continues to move the yoke toward the distal end of the applicator instrument. As the yoke  142  continues to move distally, the yoke boss  158  moves the indexer  154  distally, which results in distal movement of the advancer  166  for advancing the surgical fasteners. As the indexer moves distally, the upper slot  162  of the indexer  154  also preferably engages a tab  163  on the lockout counter  164  for at least partially rotating a lockout indicator, as will be described in more detail below. 
     Referring to  FIG. 11H , as the yoke  142  moves distally, the primary latch  150  approaches a distal opening in the primary latch raceway  152 . Once the primary latch  150  reaches the distal opening of the primary latch raceway  152 , the primary latch  150  is free to drop for de-coupling the yoke  142  from the spring block  170 . After de-coupling, the spring block  170  is free to move independently of the yoke. In one embodiment, the de-coupled spring block will move toward the proximal end of the applicator instrument in response to forces provided by the spring block return spring  184 . 
       FIG. 11H-1  shows the distal end  104  of the applicator instrument  100  during the stage of the firing cycle shown in  FIG. 11H . The insertion fork  220  cannot move further distally due to the stop wall SW in the handle engaging the positive stop on the cruciform-shaped end of the firing rod. Further distal movement of the yoke  142 , however, continues to move the indexer  154  to the left, which, in turn, moves the advancer  166  in a distal direction to advance the trailing surgical fasteners  232 B,  232 C and  232 D toward the distal end  104  of the applicator instrument  100 . 
       FIG. 11I  shows the primary latch  150  after it has reached the distal opening in the primary latch racetrack  152 . Once the primary latch  150  reaches the distal opening, the primary latch  150  is free to drop for de-coupling the yoke  152  from the spring block  170 . Once the primary latch  150  de-couples the yoke  142  from the spring block  170 , the spring block  170  and the yoke  152  move independently of one another. Referring to  FIG. 11I , as noted above, the yoke  152  is constrained from proximal movement until the projection  145  on the ratchet pawl  146  clears the right end of the yoke  152 . 
       FIG. 11I-1  shows the distal end  104  of the applicator instrument  100  after the primary latch  150  has been de-coupled from the spring block  170 . As the trigger continues to be compressed, the advancer  166  continues to move distally for advancing the surgical fasteners  232 B,  232 C and  232 D in a distal direction. 
     Referring to  FIG. 11J , as the trigger  114  continues to be compressed, the yoke  142  continues to advance the indexer  154  distally. Further distal movement of the indexer  154  moves the advancer  166  distally and moves the tab  163  on the lockout counter  164  distally. The tab  163  of the lockout counter  164  preferably frictionally engages the upper slot  162  of the indexer  154 .  FIG. 11J-1  shows the distal end  104  of the applicator instrument  100  during the stage of the firing cycle shown in  FIG. 11J . 
     Referring to  FIG. 11K , in one embodiment, after the primary latch  150  has de-coupled from the spring block, the spring block return spring  184  urges the spring block  170  to move proximally. As the spring block  170  moves to the right, the spring block  170  pulls the firing rod  174  toward the proximal end of the applicator instrument  100 . Thus, the spring block  170  and the firing rod  174  move as a unit toward the proximal end of the applicator instrument while the yoke  142  continues to move toward the distal end of the instrument under the force of the trigger  114 . In one embodiment, the yoke boss  158  continues to move the indexer  154  distally for compressing the dampening spring  186 . In one embodiment, the dampening spring  186  desirably gradually slows the user&#39;s compression of the trigger when the indexer  154  pushes against it, 
       FIG. 11K-1  shows the distal end  104  of the applicator instrument  100  during the stage shown in  FIG. 11K . After the primary latch releases the spring block from the yoke, the spring block moves to the right, thereby retracting the firing rod  174  and the insertion fork  220 . As shown in  FIG. 11K-1 , the lead surgical fastener  232 A remains implanted in tissue, while the tines  290 ,  294  have been retracted from the ribs  272 ,  274  on the lead surgical fastener. 
     Referring to  FIG. 11L , once the trigger  114  is fully compressed, the right end of the yoke  142  clears the ratchet pawl  144 . As a result, the yoke  142  is now free to move in a proximal direction. When the trigger  114  is fully squeezed, the yoke boss  158  preferably urges the indexer  154  into a distal-most position. In turn, the upper slot  162  of the indexer has preferably advanced the lockout counter  164  one-half of a cycle. With the trigger in the fully compressed position, the trigger dampening pad  132  engages an end wall of the trigger guide  129  for dampening deceleration of the trigger. 
       FIG. 11L-1  shows the distal end  104  of the applicator instrument  100  during the stage of the firing cycle shown in  FIG. 11L . Distal movement of the indexer results in distal movement of the advancer  166 . In one embodiment, as the trigger is squeezed to the fully dosed position, the second surgical fastener  2328  is advanced to the lead surgical fastener position, the third surgical fastener  2320  is advanced to the first trailing position, and the fourth surgical fastener  232 D is advanced to the second trailing position. In the stage of the firing cycle shown in  FIG. 11L-1 , the staging leaf  228  is preferably deflected downwardly by the extended insertion fork  220  and the extended advancer  166 . When the trigger begins moving into the uncompressed, open position, the advancer  166  and the insertion fork  220  are retracted, which enables the lead surgical fastener  232 B to be moved by the staging leaf  228  into alignment with the tines of the insertion fork. 
     Referring to  FIG. 11M , in one embodiment, as the trigger  114  rotates back to the open, uncompressed position, the yoke  142  moves in a proximal direction. At this stage, the ratchet pawl  144  prevents the yoke  142  from changing direction until the yoke reaches a fully retracted position. As the yoke  142  moves proximally, the primary latch  150  moves below the primary latch racetrack  152 . 
       FIG. 11M-1  shows the distal end  104  of the applicator instrument  100  during the stage of the firing cycle shown in  FIG. 11M . The new lead surgical fastener  232 B sits below the extended advancer  166  and the partially extended insertion fork  220 . The staging leaf  228  and the staging leaf support  226  remain deflected in a downward position by the extended advancer and the extender insertion fork. The staging leaf  228  is constrained from springing into an upright position due to being blocked by the advancer  166  and the insertion fork  220 . 
     Referring to  FIG. 11N , in one embodiment, the spring block return spring  184  returns the spring block  170  to its initial proximal position. In turn, proximal movement of the spring block  150  retracts the firing rod  174  and the insertion fork at the distal end of the applicator instrument. As the trigger moves to the fully open position, the yoke  142  also reaches a proximal-most position. As the yoke  142  reaches the proximal end of its range, the primary latch  150  is urged upwardly by a primary latch ramp  155  located adjacent a proximal end of the housing  106 . With the yoke  142  in a retracted position, the ratchet pawl  144  moves into a neutral position under the yoke  142 . At this stage, the yoke  142  is free to move distally and will not be constrained from distal movement by the ratchet pawl  144 . 
       FIG. 11N-1  shows the distal end  104  of the applicator instrument during the final stage of the firing cycle shown in  FIG. 11N . As shown in  FIG. 11N-1 , the advancer  166  and the insertion fork  220  are fully retracted, thereby enabling the staging leaf  228  to deflect upwardly for aligning the lead surgical fastener  232 B with the tines of the insertion fork  220 . 
     In one embodiment, the applicator instrument of the present invention may be used to repair of a defect, such as an inguinal hernia, located in inguinal tissue such as the inguinal floor. Generally, an inguinal hernia may be accessed through the iliacus muscle. As can be well appreciated, a network of vessels and nerves exist in the area of a typical inguinal hernia, which requires a surgeon to conduct a hernia repair with great skill and caution. For instance, in the transverse abdominis aponeurosis, an internal ring permits gastric vessels and Vas deferens to extend therethrough over an edge of inguinal ligament. A femoral canal is located near the Cooper&#39;s ligament and contains external iliac vessels and inferior epigastric vessels. 
     In many cases, the edge of the inguinal ligament and the Cooper&#39;s ligament serve as anatomical landmarks and support structures for supporting surgical fasteners such as those mentioned previously. The area containing the external iliac vessels and the Vas deferens may be commonly known as “the Triangle of Doom” to surgeons. Accordingly, care must be taken when performing dissection, suturing or fastening within this area. 
     A prosthetic or a mesh patch may be placed over the inguinal hernia. The mesh patch may have any desired configuration, structure or material. In one embodiment, the mesh patch may be made of PROLENE™ (a well-known polymer made of fibers) and preferably configured as mesh. 
     The mesh patch may be placed over the inguinal hernia for providing a sufficient barrier to internal viscera (not shown) of the abdomen which would otherwise have a tendency to protrude through the inguinal hernia and cause the patient a great deal of pain and discomfort. After the mesh patch has been placed onto the inguinal floor, the mesh patch is ready for attachment to the inguinal floor. 
     Referring  FIG. 12A-12D , in one embodiment, a distal end  104  of an applicator instrument  100  is positioned over a prosthetic device  270  for securing a prosthetic device, such as a mesh patch, to tissue T. The prosthetic device may be a surgical mesh having strands  272  extending therethrough. The tips of each surgical fastener are preferably spaced from one another to increase the chances that the surgical fastener will engage at least one of the strands  272 . The distal end  104  of the instrument  100  preferably includes an end cap  122  having castling  242  that facilitates holding the instrument in place over the prosthetic device  270 . 
     Referring to  FIG. 12A , the applicator instrument  100  preferably includes an outer tube  116  surrounding a ceiling stamping  200  and an anti-backup stamping  208 . The end cap  122  is coupled with the outer tube  116 , the ceiling stamping  200  and the anti-backup stamping  208 . The ceiling stamping desirably has one or more ceiling stamping spring tabs  202  for pressing against the inner surface of the outer tube  116  to provide a snug fit between the inner stampings  200 ,  208  and the outer tube  116 . The applicator instrument includes the insertion fork  220  having tines projecting from the distal end thereof. One of the tines  294  has an inner groove  296  that extends along the longitudinal axis A-A of the applicator instrument for engaging a rib on a leg of the surgical fastener. The applicator instrument includes the staging leaf assembly including the staging leaf support  226  and the staging leaf  228  for holding the surgical fasteners in alignment with the tines  294  of the insertion fork  220 . 
     The advancer  166  is preferably disposed between the insertion fork and the anti-backup stamping. The advancer  166  includes advancer tabs  230  for urging the surgical fasteners toward the distal end of the applicator instrument. The anti-backup stamping has anti-backup tabs  212  that prevent the surgical fasteners from moving proximally. 
     In  FIG. 12A , the firing system is positioned at a first stage of a firing cycle. The insertion fork  220  and the advancer  166  are retracted and the staging leaf assembly holds the lead surgical fastener  232 A in alignment with the at least one tine  294  of the insertion fork  220 . 
       FIG. 12B  shows a later stage of the firing cycle when the at least one tine  294  of the insertion fork has been piloted distally to engage the ribs on the lead surgical fastener  232 A. During piloting, the insertion fork  220  moves distally at a rate that is proportional to the rate that the trigger is squeezed. During piloting, the staging leaf tab  229  and the staging leaf  228  stabilize and hold the lead surgical fastener  232 A from further distal movement. 
     In  FIG. 12C , after potential energy has been stored in the firing spring, the firing rod  174  is released for dispensing the lead surgical fastener  232 A from the applicator instrument  100 . The firing rod drives the insertion fork  220 , which, in turn, drives the lead surgical fastener  232 A through the prosthetic device for implanting the tips of the surgical fastener in the tissue T for anchoring the prosthetic device to the tissue T. During implantation into tissue, the tines of the insertion fork preferably support the lead surgical fastener  232 A to prevent the lead surgical fastener from bending or twisting. As the insertion fork  220  and the firing rod  174  drive the lead surgical fastener  232 A into the prosthetic device and the tissue T, the trailing surgical fastener  232 B preferably remains stationary. 
     Referring to  FIG. 12D , in one embodiment, during a later stage of the firing cycle, the trigger is pulled further for advancing the advancer  166  toward the distal end of the applicator instrument  100 . The advancer tab  230  on the advancer  166  preferably engages the trailing surgical fastener  232 B for moving the trailing surgical fastener  232 B distally. During this stage, the firing rod is decoupled from the yoke so that the insertion fork  220  is free to retract and disengage from the dispensed surgical fastener  232 A. 
     Referring to  FIG. 12E , when the trigger is fully closed, the trailing surgical fastener  232 B has been advanced to a staging position by the advancer  166 . The staging leaf assembly is constrained from moving the second surgical fastener  2328  into alignment with the tines at the end of the insertion fork  220  because it blocked from such movement by the extended advancer  166  and the at least partially extended insertion fork  220 . 
     During a later stage not shown in  FIG. 12E , the trigger returns to the open position and the advancer, and the insertion fork move proximally to the positions shown in  FIG. 12A . When the advancer  166  and the insertion fork  220  are retracted to the initial position shown in  FIG. 12A , the staging leaf assembly is free to move the second surgical fastener  232 B into alignment with the at least one tine  294  of the insertion fork  220 . The applicator instrument is now ready to commence a second firing cycle during which the second surgical fastener  232 B will be dispensed from the applicator instrument for being implanted in the prosthetic device  270  and the tissue T. 
     In one embodiment, the applicator instrument includes a lockout indicator system that locks the applicator instrument from further deployment of surgical fasteners after all of the surgical fasteners have been dispensed. Referring to  FIG. 13A , in one embodiment, the lockout indicator system preferably includes a lockout counter  364  having a lockout counter boss  365 . The lockout counter preferably moves in distal and proximal directions along the longitudinal axis A-A of the applicator instrument. The lockout counter boss  365  is preferably aligned with the upper slot  362  of the indexer  354  so that the upper slot  362  is capable of sliding over the lockout counter boss  365 . In one embodiment, the lockout counter boss  365  has an outer dimension adapted to slide within the upper slot  362  of the indexer  154 , however, there is preferably frictional contact between the lockout counter boss  365  and the upper slot  362  as the lockout counter boss moves through the upper slot  362 . 
     In one embodiment, as the trigger of the applicator instrument is pulled, the yoke moves distally, which, in turn, moves the indexer  354  distally (to the left). Referring to  FIG. 13B , as the indexer  354  moves distally, the upper slot  362  of the indexer  354  slides over the lockout counter boss  365  of the lockout counter  364 . The frictional engagement between the upper slot  362  and the lockout counter boss  365  moves the lockout counter  364  distally, which, in turn, rotates the lockout indicator  375  in a counterclockwise direction. 
       FIGS. 14A-E  show a lockout indicator system, in accordance with one embodiment of the invention. The components surrounding the lockout indicator system have been removed to simplify the description of the embodiment. Referring to  FIG. 14A , the lockout indicator system desirably includes the lockout counter  364  having the lockout counter boss  365 . The lockout counter  364  includes a first tooth  380  adjacent a proximal end of the lockout counter and a second tooth  382  adjacent a leading of the lockout counter. As noted herein, the lockout counter  364  is adapted to move distally and proximally along the longitudinal axis A-A of the applicator instrument. 
     The lockout indicator system includes a lockout indicator  375  having a main ledge  384  with an alignment notch  386  and a lockout notch  388 . The alignment notch  386  desirably is utilized for properly aligning the lockout indicator  375  during initial assembly of the lockout indicator system. The lockout notch  388  provides a larger opening in the main ledge  384  that enables a lockout pin to drop therein for locking the firing system. 
     In one embodiment, the lockout indicator system includes a lock-put pin  390  having a lockout flange  392  that engages the main ledge  384  of the lockout indicator, and a lockout pin spring  394  that urges the lockout pin  390  in a downward direction once the lockout flange  392  is aligned with the lockout slot  388 . 
     Referring  FIG. 14B , as the indexer  354  moves toward the distal end of the applicator instrument (to the left in  FIG. 14B ), the upper slot  362  moves the lockout counter boss  365  distally, which, in turn, moves the lockout counter  364  distally. As the lockout counter  364  moves distally, the first tooth  380  adjacent the proximal end of the lockout counter  364  engages teeth on the underside of the lockout indicator  375 . The engagement of the first tooth  380  of the lockout counter  364  with the teeth on the underside of the lockout indicator  375  rotates the lockout indicator in a counterclockwise direction designated R 1 . As the lockout indicator  375  rotates in a counterclockwise direction, the lockout flange  392  slides over the main ledge  384  of the lockout counter  375 . As long as the lockout flange  292  is in contact with the main ledge  384 , the lockout pin cannot drop. 
     Referring to  FIG. 14C , the indexer  354  continues to move distally until the trigger is completely compressed. As the indexer  354  moves to its distal-most position, the upper slot  362  continues to urge the lockout counter boss to move distally. When the indexer  354  has advanced to its distal-most position ( FIG. 14C ), the indexer  154  may move in a proximal direction (to the right) as the trigger opens. As the indexer  354  moves proximally, the indexer will, in turn, move the lockout counter  364  in a proximal direction so that the second tooth  382  on the lockout counter engages the teeth on the underside of the lockout indicator  375 . The second tooth  382  on the lockout counter preferably further rotates the lockout counter  375  in a counterclockwise direction designated R 1 . 
     In one embodiment, one complete firing cycle will result in the lockout counter  364  moving distally and then proximally. As the lockout counter moves distally to its distal-most position, the lockout counter  364  will rotate the lockout indicator  375  another about 1/58 of a rotation. As the lockout counter  364  moves to its proximal-most position, the lockout counter will again rotate the lockout indicator  375  about 1/58 of a rotation. Thus, each complete firing cycle will result in the lockout indicator  375  rotating about 1/29 of a rotation. Eventually, the lockout indicator  375  will rotate completely so that the lockout flange  392  is aligned with the lockout slot  388  formed in the main ledge  384  of the lockout indicator. In other embodiments, the lockout indicator may rotate more or less than the example provided below. 
       FIG. 14D  shows the lockout indicator system immediately before the firing system is locked from further firing. A lockout condition may occur after all of the surgical fasteners have been dispensed. In  FIG. 14D , the lockout indicator  375  has rotated so that the lockout flange  394  is adjacent an edge of the lockout slot  388 . 
     Referring to  FIG. 14E , in one embodiment, as the indexer  354  moves proximally at the end of a trigger squeeze, the lockout counter  364  rotates the lockout indicator  375  in a counterclockwise direction so that the lockout flange  392  is aligned with the lockout slot  388 . Once the lockout flange  392  is aligned with the lockout slot  388 , the lockout pin  390  drops into the lockout slot for locking the firing system. The lockout pin  390  may be urged to drop by the lockout pin spring  394 . 
     Referring to  FIG. 15A , in one embodiment, after all of the surgical fasteners are dispensed, the lockout indicator  375  has rotated so that the lockout flange  392  is aligned with the lockout slot  388 . At this stage, the lockout pin spring  394  drops the lockout pin  390  so that a catch  396  at a lower end of the lockout pin  390  is aligned with a flange  345  on the yoke  342 . 
     Referring to  FIG. 15B , in one embodiment, during the next firing cycle the yoke  342  moves distally so that the yoke flange  345  engages the proximal end of the catch  396  of the lockout pin  390 . Referring to  FIG. 15C , in one embodiment, as the yoke moves distally, the yoke flange  345  forces the catch  396  at the lower end of the lockout pin  390  to move upwardly as the yoke  342  continues to move in a distal direction. 
     Referring to  FIG. 15D , in one embodiment, during a later stage, the yoke flange  345  moves distal of the catch  396 . In  FIG. 15E , the yoke  342  is constrained from moving in a proximal direction by the catch  396 . At this stage, the trigger is preferably completely closed and is prevented from returning to the open trigger position by the engagement of the catch  396  with the yoke flange  345 . 
     Referring to  FIG. 16A , in one embodiment, a surgical fastener  432  has a distal end  450  and a proximal end  452 . The surgical fastener  432  includes a first leg  454  having a first tip  456  adjacent the distal end  450 . The surgical fastener preferably includes a second leg  458  having a second tip  460  adjacent the distal end  450 . The proximal end  452  of the surgical fastener  432  includes a bridge  462  connecting the first and second legs  454 ,  458 . The bridge may include a concave inner surface  465  and a convex outer surface  467 . 
     Referring to  FIGS. 16B and 16C , the first leg  454  desirably ends at a first blind via  480  and the second leg  458  desirably ends at a second blind via  482 . The respective blind vias  480 ,  482  may be formed in the trailing faces of the tips and are preferably located directly over the center of each tip  456 ,  460 . The blind vias  480 ,  482  are preferably substantially aligned with the distal points of the tips to avoid tip bending and/or to direct forces for insertion directly behind each of the penetrating distal points. 
     Referring to  FIGS. 17A-17C , in one embodiment, a surgical fastener  532  includes ribs  572  provided on outer surfaces of the first and second legs  554 ,  558 . The surgical fastener  532  is deployed by an insertion fork  520  having a distal end  524  with a first prong  590  and a second prong  594 . The first prong  590  includes an inner groove  592  that slides over the first rib  572 . The second prong  594  preferably includes a second inner groove  596  adapted to slide over a second rib (not shown) on the second leg  558 . 
       FIG. 17B  shows the first and second prongs  590 ,  594  of the insertion fork  520  sliding over the ribs on the first and second legs of the surgical fastener  532 .  FIG. 17C  shows the prongs  590 ,  594  fully seated over the first and second legs  554 ,  558  of the surgical fastener  532 . The insertion fork  520  desirably provides rigidity to the surgical fastener  532  during implantation of the surgical fastener into tissue. In one embodiment, the distal ends of the first and second prongs  590 ,  594  are desirably axially aligned with the first and second tips  556 ,  560  at the distal end of the surgical fastener. Insertion force is preferably transmitted to the surgical fastener  532  by the distal ends of the tines  590 ,  594  and by a concave seat  525  of the insertion fork  520 . 
     Referring to  FIGS. 18A and 18B , in one embodiment, a surgical fastener  632  includes a first leg  654  having a first tip  656  and a second leg  658  having a second tip  660 . The first leg  654  includes a first groove  672  that extends from a proximal end  652  toward a distal end  650  of the surgical fastener  632 . The second leg  658  has a second groove  674  that is similarly formed as the first groove  672 . As shown in  FIG. 18B , the first pointed tip  656  is staggered from the second pointed tip  660 . The staggered tips desirably reduce penetration force by staggering the peak forces encountered during insertion. The surgical fastener also desirably includes at least one barb  664  on the first leg  672  that is staggered from the at least one barb  666  on the second leg  674 . 
     Referring to  FIGS. 19A-19C , in one embodiment, the surgical fastener  632  of  FIGS. 18A and 18B  is implanted using an insertion tool  620  having staggered prongs  690 A,  690 B. The surgical fastener preferably includes blind vias  680 ,  682  that are aligned with the pointed tips  656 ,  660 . The staggered prongs  690 A,  690 B of the insertion tool  620  are insertable into the blind vias  680 ,  682  located behind the pointed tips  656 ,  660 . The prongs provide support for the surgical fastener as the fastener is implanted, and provide an insertion force that is applied to the surgical fastener distal to the proximal end of the surgical fastener. 
       FIGS. 20A-20C  show the surgical fastener  632  of  FIGS. 18A-18B  being implanted using the insertion tool  620  of  FIGS. 19A-19C . Referring to  FIG. 20A , in one embodiment, a distal ends of an applicator instrument is abutted against a prosthetic device  670  overlying tissue T. The insertion tool  620  is advanced to the distal end of the applicator instrument  600  so that the first and second pointed tips  656 ,  660  are adjacent the prosthetic device. As shown in  FIG. 20A , the second pointed tip  660  engages the prosthetic device before the first pointed tip  656 , thereby staggering the peak forces encountered during implantation.  FIGS. 20B and 20B-1  show the pointed tips  656 ,  660  of the surgical fastener  632  being pressed through the prosthetic device and into the tissue. The staggered tines  690 A,  690 B at the distal ends of insertion tool  620  support the pointed tips  656 ,  660  of the surgical fastener and preferably extend through the prosthetic device and into the tissue during insertion of the surgical fastener.  FIG. 20C  shows the surgical fastener  632  in place for holding the prosthetic device  670  to the tissue T after the insertion tool has been retracted. The bridge  662  of the surgical fastener preferably overlies one of more strands of the prosthetic device for capturing the strands between the first and second legs  654 ,  658 . 
     Referring to  FIGS. 21A and 21B , in one embodiment, a surgical fastener  732  includes internally facing barbs  764 ,  766 . Referring to  FIG. 21B , in one embodiment, the barbs are preferably staggered from the distal end of the surgical fastener. After implantation, the internally facing barbs  764 ,  766  desirably squeeze tissue inside the legs, thereby increasing the required pull-out force. The surgical fastener desirably includes a bridge  762  having a substantially flat inner surface that allows for greater capture of the prosthetic device and further aids in alignment of the surgical fastener as it is advanced toward the distal end of an insertion tube. 
     Although the present invention is not limited by any particular theory of operation, it is believed that the internally facing barbs provide a greater point to point distance for a given surgical element width, thereby reducing the chance that the surgical fastener will not capture a strand when anchoring large open-pore meshes. The internally facing barbs enable the external surfaces of the legs  754 ,  758  to be straight, thereby facilitating feeding the surgical fastener inside a tube. 
     Referring to  FIGS. 21A and 21B , in one embodiment, the legs  754 ,  758  of the surgical fastener  732  have opposing inner grooves  772 ,  774 . The grooves  772 ,  774  are desirably accessible at the proximal end of the surgical fastener and adjacent the bridge  762  of the surgical fastener. The inner grooves formed in the first and second legs  754 ,  758  preferably guide tines on an insertion tool to blind vias at the distal ends of the legs  754 ,  758 . It is believed that the conical-shaped tips  756 ,  760  increase penetration force compared to tips that are chiseled, and that the conical-shaped tips may also increase pull-out force by not cutting a path, but rather stretching the hole created by the conical tips.  FIGS. 22A-22C  show an insertion tool  720  having distal tines  790 A,  7908  that are advanceable into the inner grooves  772 ,  774 . The distal ends of the tines are preferably abutted against the blind vias  680 ,  682  that terminate adjacent the tips  756 ,  760 . 
     Referring to  FIG. 23 , in one embodiment, a surgical fastener  832  has barbs  864 ,  866  that are set out of plane. The out of plane barbs preferably enhance holding force after implantation in tissue. Referring to  FIG. 24 , in one embodiment, a surgical fastener  932  is pin-less, and is desirably pushed from a proximal end during deployment into a prosthetic device, mesh or tissue. 
     Referring to  FIGS. 25A and 25B , in one embodiment, a surgical fastener  1032  is deployed using needle-assisted insertion. The surgical fastener  1032  has barbed tips  1056 ,  1060  having through holes. In one embodiment, the surgical fastener  1032  is made of relatively soft material, but may still be inserted through tough prosthetic devices, meshes and tissue using a needle-assist insertion tool  1020  having needle tips  1090 A,  1090 B that are passable through the through holes in the tips  1056 ,  1060 . 
     Referring to  FIG. 26 , in one embodiment, a surgical fastener  1132  has one-way barbs. Each of the barbs  1164 ,  1166  preferably has a notch  1165 ,  1167  that enables the barbs to flex inwardly during insertion and outwardly during retraction, thereby making it difficult to remove the barbs from prosthetic devices, mesh and/or tissue during retraction of the surgical fastener, 
     Referring to  FIG. 27 , in one embodiment, an applicator instrument  1200  has an alignment notch  1225  at a distal  1204  end therefor. As shown in  FIGS. 28A and 28B , in one embodiment, the alignment notch  1225  preferably facilitates aligning the instrument over a strand  1270  of a prosthetic device to ensure that the strand is captured between the legs  1254 ,  1258  of the surgical fastener  1232  when deployed from the applicator instrument. 
     Referring to  FIG. 29 , in one embodiment, an applicator instrument  1200  has an outer tube  1216  having one or more alignment markings  1290  extending away from the distal end  1204  and along the outer surface of the outer tube  1216 . The alignment marking  1290  preferably extends along the longitudinal axis A-A of the instrument for providing an alignment reference marking for aligning the instrument over a strand  1270  of a prosthetic device. 
     The headings used herein are for organizational purposes only and are not meant to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including but not limited to. To facilitate understanding, like reference numerals have been used, where possible, to designate like elements common to the figures. 
     While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. As such, the scope of the present invention is to be limited only as set forth in the appended claims.