Abstract:
A tray for holding surgical fasteners comprises at least one well holding one of the fasteners and a film over the well. Preferably the film is weakened, as by scoring, or slit, over the well to more easily allow an instrument to penetrate the well to remove the fastener.

Description:
[0001]    Priority is claimed to Provisional Application Ser. No. 60/234,491 filing date Sep. 22, 2000. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to an apparatus and method for applying surgical fasteners, and in one particular aspect to such an apparatus and method for driving rivets to secure cranial plates.  
         BACKGROUND  
         [0003]    It is known in the art to apply fasteners for attaching sutures, bone plates, and connective tissue. The fastener is inserted into a hole in a bone and generally through some application of force is caused to expand. One particular method for driving a fastener is disclosed in U.S. Pat. No. 5,398,861 by Green which discloses a spring loaded retractable piston and a pivotable trigger device for releasing the piston and allowing it to drive forward and drive home a fastener. One disadvantage of this device lies in the difficulty in grasping the device and firing the trigger simultaneously.  
           [0004]    To more easily access the fasteners, it would be desirable to have something which can carry the fasteners to that they will not fall out and allow easy grasping with the applier.  
         SUMMARY OF THE INVENTION  
         [0005]    A tray according to the present invention holds one or more surgical fasteners. It comprises a base have at least one well therein, one of the surgical fasteners within the base and a film over the base and the well. Preferably, some treatment of the film at the well is provided to more easily allow an instrument to penetrate the film and access the well to remove the fastener. This could comprise providing an opening through the film such as a slit, or a weakness in the film such as scoring. Preferably, the well and the surgical fastener are sterile. The film thus holds the fastener in the well and maintains the sterility.  
           [0006]    A method of holding surgical fasteners according to the present invention comprises the steps of: providing a tray having a base with at least one well therein; providing one of the surgical fasteners in the well; and covering the well with a film. Preferably, the method includes penetrating the film with an instrument and removing the fastener from the well with the instrument, which preferably is an applier for applying the surgical fastener.  
           [0007]    Preferably, the method further comprises the step of modifying the film over the well to ease the ability of the instrument to penetrate the well, such as by providing an opening in the film such as a slit, or by providing a weakness such as scoring of the film. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a top plan view of an instrument for applying surgical fasteners according to the present invention;  
         [0009]    [0009]FIG. 2 is a section view taken along lines  2 — 2  of FIG. 1;  
         [0010]    [0010]FIG. 3 is a perspective detail view of a release button for the instrument of FIG. 1;  
         [0011]    [0011]FIG. 4 is perspective view of a fastener for using in the instrument of FIG. 1;  
         [0012]    [0012]FIG. 5 is a section view taken along lines  5 — 5  of FIG. 4;  
         [0013]    [0013]FIG. 6 is a top plan view of a plate to be applied using the fastener of FIG. 4;  
         [0014]    [0014]FIG. 7 is a top plan view of a tray holding a plurality of the fasteners of FIG. 4;  
         [0015]    [0015]FIG. 8 is a sectional view taken along lines  8 — 8  of FIG. 7;  
         [0016]    [0016]FIG. 9 is a detail sectional view taken along lines  9 — 9  f FIG. 7;  
         [0017]    [0017]FIG. 10 is a perspective view of the tray of FIG. 7;  
         [0018]    [0018]FIG. 11 is a sectional view taken along lines  11 — 11  of FIG. 1;  
         [0019]    [0019]FIG. 12 is top plan view of a drill for drilling holes in a skull to receive the fastener of FIG. 4; and  
         [0020]    [0020]FIG. 13 is a sectional view taken along lines  13 — 13  of FIG. 12.  
     
    
     DETAILED DESCRIPTION  
       [0021]    Referring now to the drawings, FIGS. 1 and 2 illustrate a rivet applier  10  according to the present invention. It comprises in general an elongated cylindrical body  12 , a piston  14  restrained by a spring  16  and a release mechanism  18 . An axial bore  20  passes through the body  12  and has varying diameters. At a proximal end  22  of the body  12  a first portion  24  of the bore  20  has a relatively large diameter to accommodate the spring  16  which is coiled about the piston  14  within the first portion  24 . Intermediate portion  26  of the bore  20  has an intermediate diameter closely matched to the diameter of the piston  14 .  
         [0022]    At a distal end  28  of the body  12  a distal portion  30  of the bore  20  has a narrow diameter to accommodate a hardened setting pin  32  which projects axially from a distal end  34  of the piston  14 . Preferably, the setting pin  32  is an integral part of the piston  14 , but can alternatively be a separate piece affixed to the piston  14 .  
         [0023]    The spring  16  is caged between a flange or retaining clip  36  about the piston  14 , and a washer  38  and retaining clip  40  at the body proximal end  22 . The piston  14  passes outwardly of the body  12  through the washer  38  and retaining clip  14 .  
         [0024]    At a proximal end  42  of the piston  14  a handle  44  is provided for manual retraction of the piston  14 . The proximal half of the body  12  is provided with flutes  46  for enhancing gripability and an axial flange  48  is provided near the body distal end  28  also to enhance gripability and maneuverability of the rivet applier  10 . A flat  49  on the flange  48  inhibits rotation of the rivet applier  10 , thereby reducing the likelihood that it will roll off of a surface upon which it is placed. The body distal end  28  tapers to a narrow tip  50  to allow more precise direction of the instrument  10 . The set pin  32  is fixed within a coaxial bore  52  in the piston distal end  34 .  
         [0025]    A circumferencial groove  54  surrounds the piston  14  near its distal end  34 . A radial bore  56  passes into the body  12  adjacent the groove  54  and extends beyond the bore  20  but does not completely penetrate the body  12 . Turning also to FIG. 3 the release mechanism  18  comprises a release button  58  received within the bore  56  and a the coil spring  60  between an end of the bore  56  and the button  58  which biases the button outwardly of the bore  56 . The button  58  has a radial bore  62  through which passes the piston  14 . A radial flange  64  within the bore  62  is adapted to engage the circumferential groove  54  on the piston  14 .  
         [0026]    When the handle  44  is retracted, causing the piston  14  to retract proximally, the flange  64  rides over the surface of the piston  14  until it encounters the circumferential groove  54  into which the spring  60  causes the flange  64  to slip. This action locks the piston  14  in a retracted position as its distal motion is restrained by the abutment of the flange  64  and groove  54 . Inward pressure applied to the button  58  causes the flange  64  to disengage from the circumferential groove  54  and allows the spring  16  to drive the piston  14  forward or distally. This causes the setting pin  32  to move distally to a position flush with the distal end of the body  12 .  
         [0027]    [0027]FIGS. 4 and 5 illustrate a rivet  66  for use with the instrument  10 . The rivet  66  comprises a round head  68  from which extends axially  3  leaves  70 . A cylindrical plug  72  extends axially from the head  68  in the opposite direction and is frangible connected to the head  68  through a frangible connection  74 . The surfaces of the leaves  70  are curved so that the combination of the three leaves  70  provides an overall tubular configuration. Application of force in the axial direction applied to the plug  72  breaks its frangible connection  74  with the head  68  and allows it to drive axially into a position between the leaves  70  thus causing the leaves  70  to spread.  
         [0028]    [0028]FIG. 6 shows a cranial plate  76  for placement on a skull of an patient, either human or animal (not shown). It comprises a flat planar body  78  having a plurality of circular extensions  80  therefrom, each of which has a countersunk bore  82  therethrough. A tag  84  extends from the plate  76  and serves several functions. The tag  84  may contain model number, size, material, date and other pertinent information as well as showing which side of the plate  76  is to face upwards away from the patient&#39;s skull (not shown). It also provides a purchase location for a user&#39;s hand to hold and manipulate the plate  76  during placement. A frangible connection  86  between the tag  84  and the remainder of the plate  76  allows easy removal of the tag  84  from the plate  76  after placement of the plate  76 . Many other configurations of plates will be apparent to those of skill in the art.  
         [0029]    Turning to FIGS.  7  to  10 , the rivets  66  are disposed for use in a tray  88 . The tray  88  comprises a base  90  having a downwardly extending peripheral wall  92  and a plurality of wells  94  therein. Preferably, the wells  94  penetrate the base  90 . A plurality of the rivets  66  reside within the plurality of the wells  94  with their plugs  72  facing upwardly out of the wells  94 . A film cover  96  adheres to the base  90  over at least the area of the base  90  comprising the wells  92  to hold the rivets  66  within the wells  92 . The film cover  96  preferably has slits  97 , scorings or some other weakness at each of the wells  92  to allow access to the rivets  66  through the film cover  96  by the instrument  10  (not shown in FIGS.  8  to  10 ), although a suitable material allowing access therethrough without slits or the like may be employed.  
         [0030]    [0030]FIG. 11 illustrates the distal tip  50  of the instrument body  12 . It comprises at least one axial slit  98  extending proximally from the distal end  28  and terminating in an aperture  100 . A chamfer  102  is also provided at the distal end of the bore  20 . In one preferred embodiment, the plugs  72  of the rivets  66  (FIG. 4) have an outside diameter of 0.0590 inches (1.50 mm), the bore distal portion  30  has an inside diameter of 0.0595 inches (15.1 mm) and the outside diameter of the tip  50  is 0.140 inches (3.56 mm). The slit  98  allows the material of the tip  50  to contract slightly thus reducing the effective internal diameter of the bore distal portion  30  and the aperture  100  reduces stress risers during flexing.  
         [0031]    Preferably the rivet  66  and plate  76  are formed of a bioabsorable material such as a polylactide, such as an  85 : 15  (mol/mol) poly(lactide-co-glycolide) copolymer. More preferably, the rivet  66  is formed of PLLA and the plates are formed of 50/50 D, LPLA blended with 95/5 PCL/PDO in a 91:9 ratio as more fully described in U.S. Pat. Nos. 5,641,501 and 5,705,181, incorporated herein by reference. Preferably the instrument body  12  is formed of a sturdy material such as stainless steel, however, many other materials, including polymers, would be suitable. Preferably, the instrument body  12  weighs considerably more than the piston  14  so as to minimize kick-back as the piston  14  is released. The setting pin  32 , and especially if the setting pin  32  and piston  14  are integral, is preferably formed of a hardened steel or stainless steel, but of course many other hardy materials would be suitable for such service. The tray  88  preferably is formed of a suitable polymer, but can also be formed of other materials.  
         [0032]    To use the instrument  10 , a user grasps the handle  42  and retracts the piston  14  until the flange  64  of the release mechanism  18  engages the annular groove  54  of the piston  14  and holds the piston  14  in a retracted position. The tip  50  of the instrument  10  is inserted through one of the slits  97  to capture the plug  72  of one of the rivets  66  within the bore distal portion  30 . The chamfer  102  eases entry of the plug  72  into the bore distal portion  30  and contraction of the tip  50  due to the slit  98  helps the tip  50  grip the plug  72 . The TS rivet  66  is then placed through one of the plate apertures  82  and into a hole in the skull (not shown) and the rivet applier is held thereagainst with some force, say  2  pounds force. Pressing the button  58  releases the engagement of the piston  14  and flange  64  allowing the setting pin  32  to move distally to push against the plug  72  breaking its frangible connection to the head  68  and driving it between the leaves  70  thereby spreading the leaves and setting the rivet  66 .  
         [0033]    [0033]FIGS. 12 and 13 illustrate a bone drill  110  which provides a simple and elegant solution to the problem of centering and boring holes in a patient&#39;s skull into which the rivets  66  (not shown in FIG. 12) are received when applying the cranial plate  76  (also not shown in FIG. 12). The drill  110  comprises an elongated drill bit  112  having a proximal end  114  with an attachment surface  116  for attachment to a drill chuck (not shown). Any appropriate attachment surface can be substituted therefor. For instance, a two-piece cap (not shown) can be employed which fits into the tube instead of using a right and left half as shown. A distal end  118  of the drill bit  112  carries helical cutting edges  120 , but other forms of cutting surfaces as appropriate can be substituted therefor. A first radial flange  122  extends radially outwardly from the drill bit  112  and a second larger radial flange  124  extends radially outwardly from the drill bit  112  proximal of the first radial flange  122 . A pair of windows  123  allow debris from the drilling to exit the drill  110  and are arranged so as to release the debris before it can reach and possibly interfere with operation of the spring  140 .  
         [0034]    A tubular housing  126  having an axial bore  128  therethrough coaxially receives the drill bit  112  through the axial bore  128 . A proximal end  130  of the housing  126  abuts the second radial flange  124  and thereby limits distal movement of the drill bit  112  through the housing  126 . A first diameter  132  of the bore  128  at the housing proximal end  130  closely matches the diameter of the drill bit  112  for sliding engagement. A central diameter  134  of the bore  128  closely matches the diameter of the first radial flange  122  for sliding engagement. A distal diameter  136  of the bore  128  closely matches the diameter of the drill bit  112  for sliding engagement, and the change in diameter of the bore  128  between the central diameter  134  and distal diameter  136  forms a radial abutment  138 . A coil spring  140  encircles the drill bit  112  and operates between the abutment  138  and the first radial flange  122  to urge the housing distally along the drill bit  112 .  
         [0035]    A distal end  142  of the housing  126  carries a chamfer  144  of matching angle to the chamfer of the holes  82  in the cranial plate  76  (see FIG. 6). By pressing the distal end  142  into the chamfered hold  82  the drill bit  112  is centered within the hole  82  allowing accurate drilling. Abutment of the second radial flange  124  and the housing proximal end  130  limits travel of the drill bit  112  out of the housing  126  and thus limits the depth of a hole created by the drill bit  112 .  
         [0036]    While the invention has been described with regard to a particular embodiment thereof, those skilled in the art will understand, of course, that the invention is not limited thereto since modifications can be made by those skilled in the art, particularly in light of the foregoing teachings. Reasonable variation and modification are possible within the foregoing disclosure of the invention without the departing from the spirit of the invention.