Abstract:
Disclosed herein are apparatus, devices and methods for affixing an implant, plate, or the like to body tissue. Preferred embodiments comprise a plate with a pre-defined hole, fasteners configured for secure attachment to body tissue, and a self-centering tool capable of holding and installing multiple fasteners.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a non-provisional application claiming priority to U.S. Provisional Application No. 61/746,403, filed Dec. 27, 2012, which is incorporated herein by reference. 
    
    
     BACKGROUND ART OF THE INVENTION 
     The repair of separated or dislocated bone fragments or segments following bone surgery or injury requires realignment of the separated, broken, or dislocated fragments or segments and subsequent secure fixation for promoting proper natural rejoinder, of these bone fragments or segments, e.g. by osteosynthesis. 
     It is therefore desirable to accomplish as completely as possible an immobilization of the fracture or osteotomy site. This involves the stabilization of affected bone segments relative to each other and in relation to the surrounding bone structure. The aim of fixation of adjacent bone portions is to immobilize the fracture or osteotomy site in order to promote localized bone growth in the natural repair of the separation. 
     One example of an area in which such procedures are desirable is in the refixation of large area bone segments of the skull cap in neurosurgical and craniofacial operations on or through the vault of the human skull. 
     Another example is in the surgical treatment of craniofacial abnormalities, wherein one or more bone segments of the skull cap may be removed and reappointed to achieve a desired cosmetic result before refixation in a displaced position relative to the surrounding bone. These operations serve to correct malformations of the skull cap which are present at birth, such operations are often performed during the infancy of the patient. 
     At the end of such procedures, the previously removed bone fragment or fragments are repositioned into their original locations, or in different desired locations. 
     Known methods for providing fixation between adjacent bone portions have included the use of metallic plates of varying configurations (osteosynthesis plates), which are secured across osteotomies or fracture sites by metallic bone screws inserted with a screwdriver. 
     The typical prior-art apparatus and device used for the fixation of osteosynthesis plates is a screwdriver and self-tapping screw. Because the implementation of this apparatus and device is user dependent, users may easily strip out bone tissue causing the screw to no longer secure the plate to the bone or misalign the screw head with respect to the pre-drilled hole in the plate, creating a sharp edge and possible dermis irritation. The loading of the screw onto the screwdriver and the tightening process is time consuming. Screws are loaded by hand, one at a time, and are often lost and must be found before skin closure. Two drivers are typically utilized alternately to reduce screw loading delay time. 
     A need therefore exists for an alternative fastening device for plate/bone fixation, such as a self-centering apparatus pre-loaded with fasteners that do not strip out bone tissue or require the drilling of pilot holes. This device would save considerable time by eliminating screw loading/driving; it would also eliminate re-sterilization concerns and improve surgical outcomes. 
     SUMMARY 
     Many shortcomings in the prior art are overcome by the novel devices and methods disclosed herein, including a driving apparatus and fastener for attaching osteosynthesis plates to bone surfaces to facilitate bone stabilization/mending necessitated by traumatic injury, explorative, reconstructive, cosmetic, and/or other surgery. 
     The apparatus can hold one or more fasteners. The apparatus is visually guided and inserted into a pre-defined hole of an osteosynthesis plate. The user holds the apparatus generally perpendicular to the plate and presses the apparatus against the plate. The apparatus will automatically and rapidly drive one fastener through the pre-defined hole of the plate and into a bone, securing the plate to the bone. The apparatus automatically sequences the next fastener. 
     A preferred fastener comprises a shaft with a piercing tip connected perpendicular to a head with portions of the head having a perimeter greater than or outside the perimeter of the shaft. The head surface opposite the shaft can comprises a feature, such as a cavity, to accommodate the mating/nesting of the shaft of a subsequent fastener for the purposes of stacking. 
     In certain embodiments the fastener comprises features that will allow the bone tissue to capture and retain the fastener into the bone. 
     In certain embodiments the fastener comprises a spiral groove feature allowing the device to be rotated and easily removed from the bone. 
     In certain embodiments the fastener comprises a cavity for displaced bone tissue to gather. 
     In certain embodiments the fastener head comprises an outward taper or inward taper, or any combination thereof. 
     The cross section of fastener shaft can comprise a round, square, oval, rectangle, star or any other desired profile, or any combination thereof. 
     In certain embodiments the fastener head comprises an alignment feature to guide the fastener as it advances through the apparatus into the bone. 
     In certain embodiments the fastener comprises a bioabsorbable material. 
     In certain embodiments the fastener may be radiopaque. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention and for further advantages thereof, reference is now made to the following Description of the Preferred Embodiments taken in conjunction with the accompanying Drawings in which: 
         FIG. 1  is a perspective view of an affixation tool. 
         FIGS. 2A-2C  is an exploded view of an affixation tool. 
         FIG. 3  is a section view of a body sleeve. 
         FIG. 4  is a section view of a hammer. 
         FIG. 5A  is a top-down view of a hammer sleeve. 
         FIG. 5B  is a side view of a hammer sleeve. 
         FIG. 5C  is a bottom-up view of a hammer sleeve. 
         FIG. 6A  is a side view of a hammer finger. 
         FIG. 6B  is an enlarged view of a partial section view of a hammer finger. 
         FIG. 7A  is a side view of a muzzle of an affixation tool. 
         FIG. 7B  is a top-down view of a muzzle of an affixation tool. 
         FIGS. 7C-7E  are section views of a muzzle of an affixation tool taken along the corresponding lines indicated in  FIG. 7B . 
         FIG. 8  is a enlarged side view of an alignment rail. 
         FIGS. 9A, 10A, 11A, 12A, 13A and 14A  are each a top-down view of a different, preferred nail embodiment. 
         FIGS. 9B, 10B, 11B, 12B, 13B and 14B  are each a side view of a different, preferred nail embodiment. 
         FIGS. 9C, 10C, 11C, 12C, 13C and 14C  are each a side section view of a different, preferred nail embodiment taken along the corresponding lines indicated in  FIGS. 9A, 10A, 11A, 12A, 13A and 14A . 
         FIG. 15  is a top-down view of an affixiation tool. 
         FIGS. 16A-16B, 17A-17B, 18A-18B, 19A-19B, 20A-20B, 21A-21B and 22A-22B  are each a partial section view of an affixiation tool at a different stage of operation, taken along the corresponding lines indicated in  FIG. 15 . 
         FIGS. 16C-16D, 17C-17D, 18C-18D, 19C-19D, 20C-20D, 21AC-21D and 22C-22D  are each an enlarged partial section view of an affixiation tool at a different stage of operation, detailing a muzzle tip and components indicated in corresponding A and B Figures. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a perspective view of an affixation tool  1 . Affixation tool  1  is configured to deliver one or more a fastener  12  to secure a plate, implant, artificial organ, or the like to a suitable tissue of a patient, such as a bone. Affixation tool  1  generally comprises handle  2 , body cylinder  4 , cap  3 , and muzzle  5 . Handle  2  and body cylinder  4  are preferably molded from a polymer such as polypropylene. Handle  2  is preferably configured to be easily grasped by a user (not shown). Muzzle  5  is configured to engage a plate  20  to facilitate precise placement of an a fastener  12  to secure plate  20  to bone  30 . 
       FIGS. 2A-2C  provide an exploded view of affixation tool  1 , illustrating various internal components. Cap  3  is configured to engage body cylinder  4  and contain other internal components. Below (in this description, the terms “above” or “behind” mean toward cap  3  while the terms “below” or “forward” mean toward muzzle  5 ) cap  3  are hammer spring  22 , hammer plate  24 , and body sleeve  30 . Body sleeve  30  is further described in connection with  FIG. 3 . When affixation tool  1  is assembled, hammer spring  22  is compressed between cap  3  and hammer plate  24  within body sleeve  30 . 
     Below hammer plate  24  is hammer  40 . Hammer  40  is described in more detail in connection with  FIG. 4 . Hammer plate  24  and hammer spring  22  apply a downward force against hammer  40 . However, as will be discussed more thoroughly below, hammer  40  is prevented from moving forward until affixation tool  1  is activated. 
     Counterspring  42  is positioned between muzzle  5  and hammer  40 , extending partially through hammer  40 . Counterspring  42  aids in resetting hammer  40  to its original position after an fastener  12  has been deployed. Counterspring  42  also provides a canting tendency to hammer  40 . 
     Forward of hammer  40  is hammer sleeve  50 . Hammer sleeve  50  is generally cylindrical and concentric with body sleeve  30 . Body reset spring  46  is preferably positioned around hammer sleeve  50  and provides a force between hammer sleeve  50  and body sleeve  30 . 
     Referring to  FIG. 2B , also forward of hammer  40  are one or more hammer fingers  60 . Hammer fingers  60  are described in more detail in connection with  FIG. 6A-6B . Hammer fingers  60  are preferably configured to be positioned partially within hammer sleeve  50  and extend downwardly therefrom. A finger reset spring  62  preferably surrounds a portion of hammer fingers  60  and is configured to provide a force between hammer fingers  60  and muzzle  5 . When affixation tool  1  is assembled and loaded, one or more fasteners  12  are disposed adjacent to or between hammer fingers  60 . 
     A forward end of muzzle  5  preferably comprises one or more first sequencing springs  64 , one or more second sequencing springs  66 , and one or more positioning rails  70 . 
     Referring to  FIG. 2C , all of the above-described components of affixation tool  1  are preferably enclosed in and/or attached to body cylinder  4 . Also visible in  FIG. 2C  are plate  20  and bone  30 . 
     Referring to  FIG. 3 , body sleeve  30  is a tube comprising a generally-cylindrical outer wall  302  with an annular lip  304  surrounding its upper end. An inner wall  310  is also generally-cylindrical but preferably includes several features. First, a hammer orientation ring  312  is preferably defined on inner wall  310 . Hammer orientation ring  312  has an inner diameter smaller than the inner diameter of portions of inner wall  310  above and below hammer orientation ring  312 . Hammer orientation ring  312  preferably comprises a plate stop  314  configured to engage hammer plate  24 . Hammer orientation ring  312  also preferably comprises orientation ramp  316  configured to engage hammer  40 . Second, a reset notch  320  is defined in inner wall  310 . Reset notch  320  is preferably configured to engage body reset spring  46 . Alternatively, an annular ring (not shown), a plurality of internally-directed tabs or rungs, or other devices could be used in place of reset notch  320 . 
     Referring to  FIG. 4 , hammer  40  is generally cylindrical but comprises a plurality of segments with differing diameters. A first segment  410  preferably comprises a partially-spherical upper surface  412  and has a first outer diameter. A second segment  420  has a second outer diameter, preferably larger than the first outer diameter. A third segment  430  has a third outer diameter preferably smaller than the second outer diameter. The third outer diameter can be equal to first outer diameter. A first angular ramp  442  is defined between first segment  410  and second segment  420 . A second angular ramp  444  is defined between second segment and third segment  430 . First angular ramp  442  and second angular ramp  444  each preferably have an angle between 30 degrees and 70 degrees with respect to a centerline of hammer  40 . However, first angular ramp  442  and second angular ramp  444  can have different angles and will angle in opposite directions. 
     A spring cavity  452  is defined along at least a portion of central axis of hammer  40  and is preferably configured to receive a portion of counterspring  42 . 
       FIGS. 5A-5C  further illustrate hammer sleeve  50 . Hammer sleeve  50  is generally cylindrical and comprises one or more edge ribs  501  extending longitudinally down an exterior sleeve wall  503 . Spring tabs  502  extend laterally from edge ribs  501  near a bottom end of edge rib  501 . A hammer rim  504  surrounds the top edge. Spring tabs are configured to engage body reset spring  46  so that body reset spring  46  provides force between hammer sleeve  50  and body sleeve  30 . 
       FIG. 6A  is a larger view of a hammer finger  60 . Hammer finger  60  is preferably a generally-flat, elongate structure preferably comprising a metal such as stainless steel. A spring shelf  610  extends laterally from hammer finger  60  at around its midpoint. Spring shelf  610  is configured to engage finger reset spring  62 . An alignment guide  612  extends forwardly from an outward end of spring shelf  610 . Alignment guide  612  is preferably configured to engage guide notches  740  defined in muzzle  5 . A hammer tip  630  is defined on the forward end of hammer finger  60 . Hammer tip is preferably angled inwardly with respect to the rest of hammer finger  60 . 
     Referring to  FIG. 6B , above but preferably near hammer tip  630 , is a tip spring  640 . Tip spring  640  comprises a leaf spring  642  along an outer edge of hammer finger  60 , a spring cavity  644  immediately inward of leaf spring  642 , and an upper peninsula  646  and lower peninsula  648 . Upper peninsula  646  and lower peninsula  648  are preferably configured to contact or almost contact each other when hammer finger  60  is in a relaxed position. Tip spring  640  allows hammer tip  630  to be pushed outward from its relaxed position when an outward force is applied, but offers significantly higher resistance to inward movement of hammer tip  630 , thereby allowing hammer tip  630  to impart significant force to an fastener  12 . 
       FIG. 7A  is a closer view of muzzle  5 . The exterior of muzzle  5  is generally cylindrical muzzle wall  701  with an annular muzzle shelf  702  and a frusto-conical muzzle tip  704  at the bottom. One or more guide notch  710  is preferably defined in muzzle wall  701  from the top to a point above muzzle tip  704 . Additionally, one or more rail notch  712  is defined in muzzle wall  701  from muzzle tip  704  to a point above the bottom of guide notch  710 . Further additionally, one or more upper advancement spring notch  714  and lower advancement spring notch  716  are defined in muzzle tip  704 . 
       FIG. 7B  is a top-down view of muzzle  5 . 
       FIG. 7C  is a section view of muzzle  5  taken along line  7 C- 7 C of  FIG. 7B .  FIG. 7C  shows a cross-section of muzzle wall  701  at a point where no notches are defined in its exterior. The interior profile of muzzle wall  701  defines an upper muzzle section  722 , an intermediate muzzle section  723 , and a lower muzzle section  724 . Upper muzzle section  722  has a larger inner diameter than intermediate muzzle section  723 . Upper muzzle section  722  and lower muzzle section  724  meet at about the same height as muzzle shelf  702  and define a hammer tube shelf  726 . Intermediate muzzle section  723  has a larger inner diameter than lower muzzle section  724 . Intermediate muzzle section  723  and lower muzzle section  724  meet at a point below muzzle shelf  702  and above muzzle tip  704  and define reset spring shelf  728 . 
       FIG. 7D  is a section view of muzzle  5  taken along line  7 D- 7 D.  FIG. 7D  illustrates the configuration of upper advancement spring notch  714  and lower advancement spring notch  716 , which are configured to hold upper advancement spring  64  and lower advancement spring  66 , respectively. 
       FIG. 7E  is a section view of muzzle  5  taken along line  7 E- 7 E. In  FIG. 7E , guide notch  710  and rail notch  712  are visible. As shown, guide notch  710  extends completely through muzzle wall  701  from the top of muzzle  5  to a point above reset spring shelf  728 . A further part of guide notch  710  extends only partially through muzzle wall  701 , defining a guide channel  732 . Guide channel  732  is preferably configured to engage at least a portion of alignment guide  612  of hammer finger  60 . 
     Rail notch  712  extends up from muzzle tip  704  along both the exterior and interior of muzzle wall  701 , in a generally U-shaped configuration, around a rail guide  742 . 
       FIG. 8  is a closer view of alignment rail  80 . Alignment rail  80  is preferably a flat metal piece with a guide channel  802  defined downwardly from a top edge, and a pointed rail tip  812  at a lower end. Guide channel  802  is configured to engage rail guide  742  of muzzle  5 . Bottom tip  812  is preferably configured to engage a hole defined in plate  20  to ensure proper alignment of affixation tool  1  and fastener  12  with plate  20 . Bottom tip  812  is preferably located on or adjacent inside edge  820  of alignment rail  80 . An alignment bevel  822  is defined on the upper end of inside edge  820 . 
     All springs composing affixation tool  1  are preferably fabricated from metals such as stainless steel, spring steel, or the like. Most other components are preferably fabricated using thermoplastic polymers, such as polypropylene, polyethlene, or the like. Fasteners are preferably between 1 mm and 0.5 mm, and more preferably, between 0.55 mm and 0.45 mm. 
       FIG. 9A-9C  illustrate a preferred embodiment of an fastener  12 .  FIG. 9A  is a side view of fastener  12 . As shown, fastener  12  generally comprises a wider head portion  120  and a narrower shaft  130 . Head portion  120  preferably comprises a flat top  122  and tapered edges  124 . As illustrated in  FIG. 9B , head portion  120  also preferably comprises one or more head notch  126  defined on its perimeter. 
     Shaft  130  is generally conical. Shaft  130  preferably includes a helical groove  132  defined on its outer surface. Helical groove  132  aids in maintaining cohesion between fastener  12  and bone  30 . 
     As illustrated in  FIG. 9C , a conical nesting cavity  140  is preferably defined in fastener  12 . Nesting cavity  140  is configured to receive the forward end of shaft  130  of the next fastener  12 , if one is present. 
       FIGS. 10A, 10B, and 10C  illustrate an alternative embodiment of an fastener  12 ′. Fastener  12 ′ is essentially the same as fastener  12  except that fastener  12 ′ includes guide holes  126 ′ in place of head notches  126 . 
       FIGS. 11A, 11B, and 11C  illustrate an additional alternative embodiment of an fastener  12 ″. Fastener  12 ″ comprises head notches  126  similar to those of fastener  12 . However, head portion  120 ′ of fastener  12 ″ is not tapered on its edge, and shaft  130 ′ is only conical at its forward end. Additionally, fastener  12 ″ comprises shaft notch  132 ″ in place of helical groove  132 , and nesting cavity  140 ′ is substantially smaller. 
       FIGS. 12A-14C  illustrate additional alternative embodiments of a fasteners. 
       FIG. 15  is a top-down view of affixation tool  1 . 
       FIGS. 16A-23D  illustrate the operation of one embodiment of affixation tool  1 . Each of the A views are taken along line A-A of  FIG. 15 . Each of the B views are taken along line B-B of  FIG. 15 . 
     Referring to  FIGS. 16A-16D , affixation tool  1  is shown approaching, but not yet contacting, plate  20 . In  FIG. 14 , hammer spring  22  is held in a compressed state between cap  3  and hammer plate  24 . Hammer  40  is tilted with respect to a central axis of body tube  30 . Because of its tilted position, hammer  40  is prevented from moving forward of hammer ring  504  of hammer sleeve  50 . 
     Referring to  FIGS. 17A-17D , alignment rails  80  contact pre-defined plate hole  152  in plate  30 . In the illustrated embodiment, three alignment rails  80  contact plate hole  152 , thereby centering the affixation tool  1 . Other numbers of alignment rails or other methods of alignment can be used instead. 
     Referring to  FIGS. 18A-18D , once affixation tool is aligned, a user (not shown) begins to press downwardly on handle  2 , causing downward movement of body cylinder  4  and body sleeve  30  with respect to hammer  40 . This downward movement further compresses hammer spring  22  and causes hammer orientation ring  312  to begin contacting hammer  40 . 
     |Referring to  FIGS. 19A-19D , continued downward movement of body sleeve  40  urges hammer orientation ring  312  against second segment  420  of hammer  40 , causing hammer  40  to come into alignment with hammer sleeve  50 . 
     Referring to  FIGS. 20A-20D , once hammer  40  is sufficiently aligned with hammer sleeve  50 , the force of hammer spring  22  causes hammer  40  to move quickly through hammer ring  512  into hammer sleeve  50 . Hammer  40  then impacts hammer fingers  60 , advancing hammer fingers  60  against the head portion  120  of leading fastener  12  and forcing fastener  12  past lower sequencing springs  66  and into bone  20 . The following fastener  12  will be advanced past the upper sequencing spring(s)  64  by the compressed force of counterspring  42  and will be stopped by lower sequencing spring(s)  66 . 
     Referring to  FIGS. 21A-21D , as the user releases pressure and handle  2  returns to its original position, hammer tip  620  flexes outwardly at tip spring  630  around head portion  120  of the following fastener  12 . The next fastener  12  is restrained by upper sequencing spring  64 . 
     Referring to  FIGS. 22A-22D , hammer  40  returns to its original canted position aided by the buckling action of counterspring  42 . Hammer finger  60  returns to its original position aided by finger reset spring  62 . Body cylinder  4  returns to its original position aided by body reset spring  46 . 
     Although representative embodiments and advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.