Abstract:
A new and improved tool driver having a shaft with a longitudinal axis and opposite ends, a boss is secured at one of the shaft ends by which the tool driver is connected to a rotary tool. A tool collet is secured to the other of the shaft ends by which the tool driver may be driven by a surgical hand piece having a chuck in which the collet may be positioned. The boss is equipped with a securing device of the bayonet type having a latch mechanism which holds the rotary tool on the boss coaxially of the driver during use. In a specific embodiment, the tool driver boss comprises a first partial boss secured to the shaft. A second partial boss having a bore extending therethrough is positioned on the shaft. A stop is positioned on the shaft and a spring is positioned on the shaft between the stop and the second partial boss. The spring urges the two partial bosses together. The partial bosses are moveable from a closed position in which the two bosses are complementary and fully define the boss of the tool driver to an open position in which the two partial bosses are separated. When the two partial bosses are in their closed complementary position, the boss defines a tapered bore extending from the distal end of the boss axially of the shaft. The rotary tool has a diametral bar extending across a bottom tool driver opening with a centrally located circular disc therein. The disc of the rotary tool fits within the bore of tool shaft boss so as to concentrically locate the rotary tool and the tool shaft on the same axis. The latch mechanism holds the tool driver and the tool together in this position, whereby rotary tools of a multitude of sizes can be secured concentrically to the tool shaft when the two partial bosses are separated against the urging of the spring and in their open position, the rotary tool may be placed within and removed from the bayonet type securing device and latch mechanism.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a continuation-in-part of U.S. patent application Ser. No. 09/349,381, entitled “IMPROVED TOOL DRIVER”, filed Jul. 9, 1999. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention pertains to tool drivers and holders for rotary tools, and more particularly, to a new and improved tool driver suitable for driving acetabular reamer cups and patella cutters and glenoid reamers and other surgical tools of any size which is easily cleaned and held and guided to rotate in true concentricity with the tool driver.  
           [0004]    2. Description of the Related Art  
           [0005]    Patella cutters and acetabular reamer cups and glenoid reamers are surgical tools which are used in surgery for the insertion of artificial joints. Acetabular reamer cups are used to cut hemispherical cavities in pelvis bones for the insertion of artificial hip joints. Patella cutters are used to shape the underside of the patella or knee cap during knee replacement surgery. Glenoid reamers are used to cut hemispherical cavities in shoulder bones for the insertion of artificial shoulder joints. Patella cutters have a complex arrangement of precisely shaped cutting edges arranged around an axis of rotation for cutting the patella. Acetabular reamer cups and glenoid reamers have a complex arrangement of cutting edges arranged on a spherical surface around the axis of rotation of the cup. Acetabular reamers and patella cutters and glenoid reamers perform better when rotated precisely about the axis around which these cutting edges are positioned by design. Additionally precise tolerances cannot be achieved without precise axial rotation as designed.  
           [0006]    It is therefore highly desirable to provide a new and improved tool driver. It is also highly desirable to provide a new and improved tool driver which can be used with acetabular reamer cups, patella cutters, glenoid reamers and like rotary tools. It is also highly desirable to provide a new and improved tool driver by which rotary tools may be driven about the tool driver&#39;s longitudinal axis with preciseness such that all of the cutting edges of the rotary tool function as designed.  
           [0007]    Rotary tools also come in a full range of sizes. Acetabular reamer cups range in size from about 36 millimeters in diameter to about 72 millimeters in diameter. In the past, a specific tool driver could only be used with one or few of the sizes of available tools. Thus, in any operating room there had to be several tool drivers. It is therefore also highly desirable to provide a new and improved tool driver by which acetabular reamer cups and patella cutters and glenoid reamers of all sizes can be driven.  
           [0008]    Unique to some knee surgery and some hip operations is the utilization of milled bone, tissue and debris as filler to be placed between the artificial insert and the body to assist the healing process. Thus, acetabular reamer cups and patella cutters and glenoid reamers are mounted on tool drivers in a manner to collect such debris for such use. It is therefore, also highly desirable to provide a new and improved tool driver on which the rotary tools of the type which collect milled bone tissue and other debris for use as filler can be used.  
           [0009]    In all surgery utilizing rotary tools, rotary tools such as those driven by rotary tool drivers must be separable from their tool drivers to replace or sharpen as required. It may also be necessary to change tools during an operation, thus, both the rotary tools and the tool drivers must at times be cleaned, sterilized and reused. Thus, it is therefore also highly desirable to provide a new and improved tool driver which can be easily cleaned, sterilized and reused.  
           [0010]    Some previous tool drivers grip the tool utilizing opposed pins, flanges and slots, or opposed spring loaded ball catches, or other such devices. These devices represent a problem in that the catches tend to trap dried blood and other debris which are very difficult to remove during a cleaning process. It is therefore also highly desirable to provide a new and improved tool driver which is simple in construction, easy to use and does not have opposed pins, flanges, slots and other devices in which to catch debris and render the tool driver difficult to clean, sterilize and reuse.  
           [0011]    An additional problem is that unless tolerances of tools and tool drivers are made very close, at a greatly increased cost, there is considerable free play between the tool and the tool driver. This increased play increases the wear of the cutting edges, makes more difficult the positioning of the tool, renders the tool useless for holding close tolerances, requires the tool not to cut as designed, and there is no possibility of utilizing the rotary tool spinning precisely about its axis as designed. It is therefore, also highly desirable to provide a new and improved tool driver which allows the rotary tool to be utilized spinning precisely about its axis, as designed.  
           [0012]    It is also highly desirable to provide a new and improved tool driver in which close tolerances can be held.  
           [0013]    Finally, it is highly desirable to provide a new and improved tool driver which has all of the above desired features.  
         SUMMARY OF THE INVENTION  
         [0014]    It is therefore an object of the invention to provide a new and improved tool driver.  
           [0015]    It is also an object of the invention to provide a new and improved tool driver which can be used with both acetabular cups, patella cutters, glenoid reamers and like rotary tools (i.e., orthopedic implant preparation tools).  
           [0016]    It is also an object of the invention to provide a new and improved tool driver by which rotary tools may be driven about the tool drivers longitudinal axis with preciseness such that all of the cutting edges of the rotary tool function as designed.  
           [0017]    It is also an object of the invention to provide a new and improved tool driver which acetabular reamer cups of all sizes and patella cutters and glenoid reamers can be driven.  
           [0018]    It is also an object of the invention to provide a new and improved tool driver on which the rotary tools of the type which collect milled bone tissue and other debris for use as filler, can be used.  
           [0019]    It is also an object of the invention to provide a new and improved tool driver which can be easily cleaned, sterilized and reused.  
           [0020]    It is also an object of the invention to provide a new and improved tool driver which allows the rotary tool to be utilized spinning precisely about its axis as designed.  
           [0021]    It is also an object of the invention to provide a new and improved tool driver which is simple in construction, easy to use and does not have opposed pins, flanges, slots and other devices in which to catch debris and render the tool driver difficult to clean, sterilize and reuse.  
           [0022]    It is also an object of the invention to provide a new and improved tool driver in which close tolerances can be held.  
           [0023]    It is finally an object of the invention to provide a new and improved tool driver which has all of the above desired features.  
           [0024]    In the broader aspects of the invention there is provided a new and improved tool driver having a shaft with a longitudinal axis and opposite ends, a boss is secured at one of the shaft ends by which the tool driver is connected to a rotary tool. A tool collet is secured to the other of the shaft ends by which the tool driver may be driven by a surgical hand piece having a chuck in which the collet may be positioned. The boss is equipped with a securing device of the bayonet type having a latch mechanism which holds the rotary tool on the boss coaxially of the driver during use. In a specific embodiment, the tool driver boss comprises a first partial boss secured to the shaft. A second partial boss having a bore extending therethrough is positioned on the shaft. A stop is positioned on the shaft and a spring is positioned on the shaft between the stop and the second partial boss. The spring urges the two partial bosses together. The partial bosses are moveable from a closed position in which the two bosses are complementary and fully define the boss of the tool driver to an open position in which the two partial bosses are separated. When the two partial bosses are in their closed complementary position, the boss defines a tapered bore extending from the distal end of the boss axially of the shaft. The rotary tool has a diametral bar extending across a bottom tool driver opening with a centrally located circular disc therein. The disc of the rotary tool fits within the bore of tool shaft boss so as to concentrically locate the rotary tool and the tool shaft on the same axis. The latch mechanism holds the tool driver and the tool together in this position, whereby rotary tools of a multitude of sizes can be secured concentrically to the tool shaft when the two partial bosses are separated against the urging of the spring and in their open position, the rotary tool may be placed within and removed from the bayonet type securing device and latch mechanism. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    The above-mentioned and other features and objects of the invention and the manner of attaining them will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings wherein:  
         [0026]    [0026]FIG. 1 is an exploded perspective view of the tool driver of the invention showing two sizes of acetabular reamer cups and patella cutters exploded therefrom, illustrating the versatility of the new and improved tool driver of the invention;  
         [0027]    [0027]FIGS. 2A and 2B are side views of the new and improved tool driver of the invention illustrated in FIG. 1 taken perpendicularly with respect to each other;  
         [0028]    [0028]FIG. 3 is a fragmentary sectional view of the new and improved tool driver of the invention illustrated in FIGS. 1 and 2 taken along the section line  3 - 3  of FIG. 2A;  
         [0029]    [0029]FIG. 4 is a cross-sectional view of the new and improved tool driver of the invention illustrated in FIGS.  1 - 3  taken substantially along the section line  4 - 4  of FIG. 2A;  
         [0030]    [0030]FIG. 5 is a top planar view of the head of the new and improved tool driver of the invention illustrated in FIGS.  1 - 4 ;  
         [0031]    [0031]FIG. 6 is a perspective view of the head of the new and improved tool driver of the invention illustrated in FIGS.  1 - 5 ;  
         [0032]    [0032]FIG. 7 is a perspective view of the trigger of the new and improved tool driver of the invention illustrated in FIGS.  1 - 5 ;  
         [0033]    [0033]FIG. 8 is a perspective view of the pins which are secured to the trigger of the new and improved tool driver of the invention and which extend upwardly through the head of the new and improved tool driver of the invention;  
         [0034]    [0034]FIG. 9 is a perspective view of the shaft to which is secured the head and on which the trigger and handle is assembled;  
         [0035]    [0035]FIG. 10 is an exploded fragmentary perspective view of a modified version of the tool driver of the invention showing the shaft and the partial boss or head secured to the shaft and the trigger with the partial boss secured to the trigger;  
         [0036]    [0036]FIG. 11 is a top planar view of the tool driver of the invention illustrated in FIG. 10 with the partial bosses of both the head and the trigger complementary assembled;  
         [0037]    [0037]FIG. 12 is a fragmentary perspective view of the head and shaft of the assembled new and improved tool driver of the invention shown in FIG. 10 from a direction 90° opposite that shown in FIG. 10;  
         [0038]    [0038]FIG. 13 is a fragmentary side view of the tool driver of the invention in its complementary assembled condition as shown in FIG. 1;  
         [0039]    [0039]FIG. 14 is a fragmentary perspective view of the trigger of the assembled new and improved tool driver of the invention illustrated in FIG. 10 from a direction 90° opposite that shown in FIG. 10;  
         [0040]    [0040]FIG. 15 is a partial break away, side view of another embodiment of a tool driver of the present invention;  
         [0041]    [0041]FIG. 16 is a cross-sectional view taken along section line  16 - 16  of the tool driver shown in FIG. 15;  
         [0042]    [0042]FIG. 17 is an exploded view of the tool driver shown in FIG. 15;  
         [0043]    [0043]FIG. 18 is an end view of the tool driver shown in FIG. 15; and  
         [0044]    [0044]FIG. 19 is an enlarged view of the bias button and surrounding portion of the tool driver shown in FIG. 16. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0045]    Tool driver  10  comprises a shaft  12  having opposite ends  14 ,  16  as shown in FIG. 1. At end  14 , a boss or head  18  is secured to the shaft  12 . At end  16 , a tool collate  20  is secured to shaft  12 . Shaft  12  has an elongated axis  22  about which both boss or head  18  and collate  20  are positioned and rotated during use. Boss or head  18 , collate  20  and shaft  12  are coaxially aligned in end to end relation. Coaxially positioned on the shaft  12  is a tubular trigger  24  and a handle  26 . Handle  26  is free to rotate about the shaft  12  between a pair of spaced apart rings  28  and  30  (ring  30  may be optional) which are secured to shaft  12 .  
         [0046]    Shaft  12  is made up of head  18 , a rod  32  and collate  20 . Rod  32  has opposite ends  34  and  36 . Similarly, head  18  has opposite ends  38 ,  40 . Head  18  at end  38  has a bore  42  extending axially of head  18 . Head  18  has a boss  44  at end  40  and a tubular portion  46  extending from boss  44  to end  38 . Bore  42  extends from end  38  to adjacent boss  44 . A slot  50  extends transversely of the tubular portion  46  adjacent boss  44  through the bore  48 . Slot  50  is elongated in an axial direction as shown.  
         [0047]    End  36  of rod  32  is shaped so as to be telescopically received in bore  48  adjacent end  38  of head  18 . Rod  32  is secured to head  18  by a pin  52  extending through hole  53  and secured at its opposite ends in ring  28 . In other specific embodiments, head  18  and rod  32  or rod  32  and ring  28  may be integrally formed as a single piece. A second pin  52  extends through the ring  30  in the manner above described with regard to the attachment of the head  18  to the rod  32  by ring  28  to secure ring  30  to rod  32  remote from ring  28 . Positioned on rod  32  between rings  28  and  30  is tubular handle  26 . Handle  26  is coaxial of the rod  32  and is free to rotate independently of rod  32  and to move axially of rod  32  between rings  28 ,  30 .  
         [0048]    Similarly positioned on tubular portion  46  of head  18  is trigger  24 . Trigger  24  is also free to slide axially of tubular portion  46  between boss  44  and ring  28  except for the engagement of a pin  54  which extends through trigger  24 , through slot  50  in head  18 , and is secured at its opposite ends to trigger  24 .  
         [0049]    A spring  58  is positioned within bore  42  of head  18  and compressed between end  36  of rod  32  and pin  54 . In a specific embodiment where head  18  and rod  32  are integral, spring  58  is positioned about shaft  12  between trigger  24  and ring  28 . Pin  54  limits the movement of trigger  24  on tubular portion  46  of head  18  both rotatably about tubular portion  46  and axially of tubular portion  46 . See FIGS. 3 and 6.  
         [0050]    Boss  44  of head  18  has a distal end  62  and a bore  64  extending axially from distal end  62  of head  18 . Bore  64  is tapered as shown in FIGS. 3 and 5 so as to have a bottom  66 , a bottom diameter  68 , a top diameter  70  and tapered side walls  72 . A groove  74  is machined in boss  44  so as to extend diametrically across bore  64  and to have a width which is equal or larger than the diametral rod or bar  60  of the tool  78  which will be used with the tool driver  10 . A second diametral groove  80  extends across the bore  64  with a bottom  82  in the same plane as the bottom  84  of the groove  74  and the bottom  66  of the bore  64 . Groove  80  is overlaid with a portion  86  of the distal end of the head  18  to form a bayonet-type latch. See FIGS. 4 and 5. Groove  74  and bore  64  both have a peripheral tapered surface  88  defining the entry of both bore  64  and groove  74 . Bottom  82 ,  84  have holes  90  therein extending through the head  18  to receive the pins  92  on trigger  24 . Groove  74  is bounded on one side by a side wall  94  and on the other side by groove  80 . Groove  80  has a floor or bottom  96  in the same plane as bottoms  66 ,  82  and  84 , an upstanding side wall  98 , and a ceiling  100 . Bottom  96  and ceiling  100  are tapered toward side wall  98  as will be explained hereinafter.  
         [0051]    As shown in FIGS. 3 and 7, trigger  24  has a bore  102  extending axially therethrough. Transversely of trigger  24  is a pin bore  104  in which the opposite ends of pin  54  are secured. Trigger  24  is slideably mounted upon tubular portion  46  of head  18 . Portion  46  is positioned within bore  102 . Trigger  24  has a boss  106  which is urged by the spring  58  against boss  44  of the head  18 . In the distal end of boss  106  are a pair of diametrically opposed pin bores  108 . Pin bores  108  extend axially of trigger  24 , and pin bores  108  are positioned with respect to each other such that when pin  54  attaches trigger  24  to head  18 , pin bores  108  are coaxial with the pin bores  90  of boss  44  of head  18 .  
         [0052]    Pins  92  are positioned in pin bores  108 . Pins  92  have opposite ends  112 ,  114 . At end  112  is a shank  116  which is secured within a pin bore  108 . Shank  116  extends from end  112  and terminates at step  118 . Adjacent the opposite end  114  is a tapered surface  120 , the purpose of which will be mentioned hereinafter. Between tapered surface  120  and shank  116  is a cylindrical pin portion  122  which is slideably positioned within pin bores  90  of head  18  and boss  44  of head  18 . See FIG. 3.  
         [0053]    In a specific embodiment, rod  32  is from about 7 to about 11 inches in axial length, has a diameter of approximately 0.375 inches in diameter and made of stainless steel. Handle  26  is from about 5 to about 5.5 inches in length. Bore  123  therethrough is approximately 0.5 inch in diameter. Handle  26  is made of molded polyethylene. Trigger  24  is from about 1.25 inches to about 1.5 inches in axial length, and has a diameter from about 0.375 to about 1.25 inches in diameter and bore  48  extending therethrough is about 0.5 inches in diameter. The pin holes  108  are about 0.1 inches in diameter. Pins  90  are approximately 0.431 inches in diameter. Both trigger  24  and pins  90  are made of stainless steel. Head  18  is approximately 2½ inches long with boss  44  having an axial length of about 1.0625 inches. Head  18  is machined from stainless steel. Bore  48  in tubular portion  46  is approximately 0.25 inches in diameter and bore  64  is approximately 0.550 inches in diameter with a top diameter of 0.637 and a bottom diameter of 0.550 inches. Slot  50  has a width of about 0.125 inches and groove  80  has a width of approximately 0.266 inches. The outside diameter of boss  44  is approximately 1 inch.  
         [0054]    In a specific embodiment, diametral rod or bar  60  of the tool  78  is approximately 0.26 inches in width, approximately 0.125 inches in thickness and has a diametral length commensurate with the diameter of the tool  78 . The central disc  134  of rod  60  has a diameter of about 0.550 inches and a thickness of about 0.125 inches.  
         [0055]    Referring now to FIG. 1, the rotary tool  78  of tool driver  10  is shown to have a hollow interior  124 . The rotary tool  78  can be either an acetabular reamer  126  or a patella cutter  128 . Each of the rotary tools  78  have a rear opening  130  which provides access to the interior  124  such that milled bone, tissue and other debris may be collected within the interior  124  and removed for use during the surgical procedure as desired. Each of the rotary tools has extending across the opening  130  a diametral bar or rod  60 . Equally distant between the ends of the diametral bar  60  is a centering disc  134 . Centering disc  134  has a diametral relationship with bore  64 , and diametral bar  60  has a diametral relationship with both grooves  74 ,  80  as will be mentioned hereinafter. Rotary tools  78  are provided in a variety of sizes ranging from 36 millimeters in diameter to 72 millimeters in diameter. Each of these rotary tools, however, have a diametral mounting bar  60  and a centering disc  134  of the same dimensions for reasons to become clear hereinafter.  
         [0056]    In operation, the rotary tool  78  to be driven by the tool driver  10  is selected and positioned adjacent the distal end  62  of the boss  44 . The diametral mounting bar or rod  60  is aligned with groove  74  and moved axially toward end  16  of the shaft  12 . Diametral bar  60  may engage the taper  88  and be guided by the taper  88  into the groove  74 . Groove  74 , between pin  90  and the groove side  94  opposite pin  90 , has a sufficient width to accommodate the bar  60 . The centering disc  134  is dimensioned with respect to the bore  64  such that it centers the bore  64  and the centering disc  134  of the tool  78  and positions the tool  78  and the shaft  12  coaxially on axis  22 , the axis of rotation of the shaft  12 . Thus, the diametral periphery of the centering disc  134  may engage the taper  88  and then the wall  72  of the bore  64  to be guided into its coaxial position and to rest on the bottom  66  or thereabouts. Inasmuch as the groove  74  does not have tapered walls, but the bore  64  does, the difference in the top diameter  70  and the bottom diameter  68  of the bore  64  will function with the centering disc  134  to center the tool  78  coaxially of the shaft  12 .  
         [0057]    The taper of the bore  64  centers the tool  78  coaxially of the shaft  12  irrespective of the holding of tolerances of either the bore  64  or the centering disc  134 . Even if tolerances are held loosely, the tapered sides of bore  64  between the bottom diameter  68  and the top diameter  70  center the centering disc  134  on the axis  22  and position the centering disc coaxially of the shaft  12 . Different dimensions of the bore  64  or the centering disc  134  within loose tolerances would position the centering disc  134  at various positions spaced apart from bore bottom  66 . However, in each of these positions, the centering disc  134  and the rotary tool  78  would still be coaxial of the shaft  12 .  
         [0058]    Once the centering disc  134  and the diametral bar  60  are positioned within bore  64  and groove  74 , respectively, pins  92  may be retracted by moving the trigger  24  toward end  16  against the resiliency of the spring  58 . By moving the trigger  24 , the pin  54  is moved toward the end  36  of shaft  12 , compressing the spring  58  and retracting the pins  92  into the pin holes  90 . With pins  92  retracted, the tool  78  can be rotated with respect to the shaft  12  so as to move the diametral bar  60  from groove  74  into the bayonet-type catch  136  defined by groove  80 , its bottom  82 , its overlaying portion  86 , upstanding groove wall  98  and top wall  100 . Bottom  82  and top wall  100  are also tapered, again to make unnecessary close tolerances, and to hold bar  60  against axial movement therebetween.  
         [0059]    Diametral bar  60  can then be held fast within the bayonet catch  136  by releasing the trigger  24  and allowing the spring  58  to urge the trigger  24  against the boss  44  to move the pins  92  back into their at rest position. Pins  92 , and specifically the tapered portions  120  thereof, engage the diametral bar  60  and urge the diametral bar  60  toward the wall  98  of the groove  80 . By its tapered portion  120 , pins alleviate any need for holding close tolerances between the wall  98  and the pin holes  90  or in the width of the diametral bar  60 . Additionally, the tolerances between wall  100  and bottom  82  of groove  80  need not be held close, as well as the tolerances of the dimensions of the diametral bar  60 , the tolerances between bottom  82  and top wall or ceiling  100 , the tolerances between the centering disc  134  and the bore  64 , and the tolerances between the diametral bar  60  and the opposite walls  98  of the groove  80  and the tapered pin portion  120  to hold the rotary tool  78  coaxially of the shaft  12  and immovable relative to shaft  12 . Because of the taper of the bore  64  and the taper of the pin  92 , lateral movement of the tool  78  with respect to the shaft axis  22  and rotary movement about the shaft axis  22  of the tool  78  is prevented. Axial movement of the diametral bar  60  is prevented by the taper between wall  100  and bottom  82  of groove  80 . Thus, no close tolerances are necessary in the manufacture of the rotary tool driver  10  of the invention.  
         [0060]    To release the rotary tool  78  of the invention from the new and improved tool driver  10  of the invention, the process is reversed. The trigger  24  is urged against spring  58  toward end  36  of the rod  32  withdrawing the pins  92  into the pin holes  90 , the rotary tool  78  is rotated about the axis  22  so as to position the diametral bar  60  in the groove  74  and the rotary tool  78  can then be separated by moving the rotary tool relative to the tool driver  10  axially thereof and a new rotary tool  78  can be installed as above described.  
         [0061]    Referring to FIGS.  10 - 14 , a modified version  140  of the tool driver  10  is shown. Tool driver  140  comprises a shaft  12  having opposite ends  14 ,  16 . At end  14 , a boss or head  142  is secured to shaft  12 . At end  16 , tool collet  20  is secured to shaft  12 . Shaft  12  has an elongated axis  22  about which both boss or head  142 , collet  20  and shaft  12  are coaxially aligned in end to end relation. Coaxially positioned on the shaft  12  is a trigger  150  and a handle  26 . Handle  26  is free to rotate about the shaft  12  between a pair of spaced apart rings  28  and  30  which are secured to shaft  12 .  
         [0062]    Shaft  12  is made up of part head  146  and collet  20 . Shaft  12 , part head  146  and collet  12  may be integrally formed by machining the same from a single piece of material. Part head  146  has opposite ends  38 ,  40 . Part head  146  at end  38  has a bore  42  extending axially of part head  146 . Spaced apart rings  28 ,  30  are secured to shaft  12  as above described. Positioned on shaft  12  between rings  28  and  30  is tubular handle  26 . Handle  26  is coaxial of shaft  12  and is free to rotate independently of shaft  12  and to move axially of shaft  12  between rings  28 ,  30 . Similarly positioned on shaft  12  is trigger  150 . Trigger  150  is also free to slide axially of shaft  12  between part head  146  and ring  28 . A spring  58  is positioned between trigger  150  and ring  28 . Spring  58  urges trigger  150  in contact with part head  146 .  
         [0063]    Trigger  150  has a bore  102  extending axially therethrough. Trigger  150  has opposite ends  152 ,  154 . Adjacent end  152  is a part boss  156 . Adjacent end  154  is a thumb groove  158 . Trigger  150  is mounted on shaft  12  between ring  28  and part head  146 . Spring  58  urges part boss  156  into engagement with part head  146 . When engaged, part boss  156  and part head  146  form boss  18 . Thus, part head  146  and part boss  156  are complimentary to each other. When part head  146  and part boss  156  are positioned together in complimentary position  184 , part head  146  and part boss  156  define bore  64 , groove  74  and groove  80  as above described.  
         [0064]    Part boss  156  comprises a disc  160  through which concentrically positioned bore  102  passes. Diametrically opposite each other and upstanding from disc  160  are two pillars  162  which are identical in all respects. Pillars  162  have a pillar wall  164 , at least a portion of which is angled relative to disc  160  to aid insertion of tool  78 , and opposite upstanding wall  166 . Wall  166  is fragmented into a lower planar portion  168  which is generally perpendicularly aligned to disc  160 , an upper planar portion  170  which is tapered inwardly of pillars  162 , a generally planar surface  172  which is generally parallel to the surfaces of disc  160  and a planar surface  174  which is again tapered inwardly of pillars  162 . The taper of surface  174  is more severe than the taper of surface  170 . See FIGS. 11 and 12.  
         [0065]    Interior surfaces  176  and  178  of pillars  162  define a part of bore  64  and are tapered to define a bottom  66 , bottom diameter  68 , top diameter  70  and tapered side walls  72  as afore described. Internal conical surfaces  176 ,  178  define bore  64  in full when part head  146  and part boss  156  are assembled in their complimentary position  184 . Extending from part boss  156  is tubular portion  76  through which bore  102  extends from end  152  to end  154  and thumb groove  158  circumferentially extends. Extending from end  154  is bore  182 . Bore  182  cooperates with ring  28  to enclose spring  58 .  
         [0066]    Part head  146  is secured to end  14  of shaft  12 . Part head  146  also includes a pair of diametrically opposed pedestals  186  secured on opposite sides of shaft  12 . Pedestals  186  are also identical, and thus, the description of one will suffice for the other. Pedestals  186  are spaced apart by bottom  66  of bore  64  as described above. Each pedestal  186  has an interior surface  188  adjacent to bottom  66  and an upper interior surface  190 . Surfaces  188  and  190  are tapered as above described with regard to surfaces  176  and  178  and tapered side walls  172 . Surfaces  176 ,  178 ,  188  and  190 , when part head  146  and part boss  156  are put together in complimentary position  184 , define bore  64  to have bottom  66 , a bottom diameter  68 , a top diameter  70  and tapered walls  72  as above described. Pedestals  186  also have an upstanding, generally perpendicular planar side wall  192  which is complimentary to pillar wall  164  when part head  146  and part boss  156  are positioned together in complimentary position  184 . Pedestal  186  has an opposite, generally perpendicular upstanding side wall  194  into which diametral groove  80  extends into. Groove  80  has bottom  82  in the same plane as bottom  66  and is overlaid with portion  86  to form a bayonet-type latch. Opposite side wall  194  is complimentary to surfaces  168  and  170  when part head  146  and part boss  156  are put together in complimentary position  184 . Pedestals  186  are separated by groove  74  which extends diametrically across bore  64  and has a width which is equal or larger than the diametral rod or bar  60  of the tool  78  which will be used with the tool driver  140 . Groove  74  and bore  64  both have a peripheral tapered surface  88  defining the entry of both bore  64  and groove  74  when part head  146  and part boss  156  are put together in complimentary position  184 . Groove  74  is bounded on one side by a side wall  94  and on the other side by groove  80 . Groove  80  has a bottom  96  in the same plane as bottoms  66 ,  82  and  84  and upstanding side wall  98  and a ceiling  100 . Bottom  96  and ceiling  100  are tapered toward side wall  98  as explained above. Tapered wall  170  of pedestals  162  act in conjunction with tapered bottom  96  and ceiling  100  to wedge rod or bar  60  of the tool  78  which is secured to the tool driver  140  in groove  80  as desired.  
         [0067]    When part head  146  and part boss  156  are placed together in complimentary position  184 , they form boss or head  18  as above described. Because of the tapers of bottom  96  and ceiling  100  and side wall  166 , whenever a rod or bar  60  of the tool  78  is positioned in groove  80 , part head  146  and part boss  156  are held in a partially complimentary position  196  by spring  58 . The tapers of bottom  96 , ceiling  100  and side wall  166  wedge bar  60  and tool  78  in groove  80  and hold tool  78  fast in a totally coaxial position with regard to shaft  12 . How closely the partially complementary position  196  is to complementary position  184  depends upon the tolerances of tool  78  and part bosses  146 ,  156 .  
         [0068]    In a specific embodiment, rod  32  is from about 7 to about 11 inches in axial length, has a diameter of approximately 0.375 inches in diameter and made of stainless steel. Handle  26  is from about 5 to about 5.5 inches in length. Bore  123  therethrough is approximately 0.5 inch in diameter. Handle  26  is made of molded polyethylene. Trigger  24  is from about 1.25 inches to about 1.5 inches in axial length, and has a diameter from about 0.375 to about 1.25 inches in diameter and bore  48  extending therethrough is about 0.5 inches in diameter.  
         [0069]    In operation, the rotary tool  78  to be driven by tool  140  is selected and positioned adjacent the distal end  62  of the boss  44 . The diametral mounting bar or rod  60  is aligned with the groove  74  and moved axially toward end  16  of the shaft  12 . Diametral bar  60  may engage the taper  174  and be guided by the taper  174  into groove  74 . Groove  74  between side  192  and  194 , has sufficient width to accommodate bar  60 . The centering disc  134  is dimensioned with respect to the bore  64  such that it centers the bore  64  and the centering disc  134  of the tool  78  and positions the tool  78  on the shaft  12  coaxially on axis  22 , the axis of rotation of the shaft  12 . Thus, the diametral periphery of the centering disc  134  may engage the taper  88  and then walls  72 , initially tapered surface  190  and subsequently tapered surface  188  of the bore  64  to be guided into its coaxial position and to rest on bottom  66  or thereabouts. Inasmuch as the groove  74  does not have tapered walls, but the bore  64  does, the difference in the top diameter  70  and the bottom diameter  68  or the bore  64  will function with the centering disc  134  to center the tool  78  coaxially of the shaft  12 .  
         [0070]    Once the centering disc  134  and the diametral bar  60  are positioned within the bore  64  and groove  74 , respectively, the trigger  24  may be moved toward end  16  against the resiliency of the spring  58 . By moving the trigger  24 , part boss  156  is moved toward end  16  allowing centering disc  134  to approach bottom  66  of bore  64  and diametral bar  60  to rest on the bottom of groove  74 . In this position, tool  78  can be rotated with respect to the shaft  12  so as to move the diametral bar  60  from groove  74  into the bayonet-type catch  136  defined by groove  80 , its bottom  82 , its overlaying portion  86 , upstanding groove wall  98  and ceiling  100 . Bottom  82  and ceiling  100  are tapered, again to make unnecessary close tolerances, and to hold bar  60  against axial movement.  
         [0071]    Diametral bar  60  can then be held fast within bayonet-type catch  136  by releasing trigger  24  and allowing the spring  58  to urge the trigger  24  and part boss  156  into its complimentary position  184  with part head  146 . Surface  170  then engages diametral bar  60  and forces diametral bar  60  against its taper toward wall  98  of the groove  80  against the taper of bottom  82  and ceiling  100 . By its tapered portion, tapered wall  170 , there is no need for holding close tolerances between the wall  98  and wall  170  or the width of the diametral bar  60 . Additionally, the tolerances between ceiling  100  and bottom  82  and groove  80  need not be held close as well as the tolerances of the dimensions of the diametral bar  60 , the tolerances between bottom  82  and ceiling  100 , the tolerances between the centering disc  134  and the bore  64  and the tolerances between diametral bar  60  and the opposite walls  98  of the groove  80 . Because of these tapered surfaces, the rotary tool  78  will always be held coaxially of the shaft  12  and immoveable relative to the shaft  12 , both in radial directions and axially without close tolerances.  
         [0072]    To release the rotary tool  78  of the invention from the tool driver  140 , the process is reversed. The trigger  24  is urged against spring  58  toward end  16  of shaft  12  and the rotary tool  78  is rotated about axis  22  from groove  80  into groove  74 . With the diametral bar  60  of the tool  78  in groove  74 , the rotary tool  78  can then be separated from the tool driver  140  by moving the rotary tool relative to the tool driver  140  axially thereof, and a new rotary tool  78  can be installed as above described.  
         [0073]    Tool drivers  10  and  140  may be totally “field strippable” for sterilization purposes whenever desired, by utilizing pins  52  and  54  which are removable whenever desired. By removing the pin  52  which secures ring  30  to rod  32 , ring  30  may be removed from rod  32  and tubular handle  26  may be removed from rod  32  by passing ring  30  and handle  26  over collate  20 . Similarly, by removing pin  52  which secures ring  28  to rod  32  and secures head  18  and rod  32  together, head  18 , part heads  146 ,  156 , rod  32 , shaft  12 , spring  58  and ring  28  may be disassembled into separate integral pieces. Similarly, by removing pin  54 , triggers  24  and  150  can be disassembled from head  18  and part head  146 , respectively.  
         [0074]    Once totally disassembled, tool driver  10  is in a number of pieces that can be easily cleaned and sterilized. The sterilized pieces can than be easily reassembled by repositioning pins  52  and  54  as disclosed. In a specific embodiment, pins  52  and  54  may be conventional screws having a head at one end and threads at the opposite end. Alternatively, pins  52  and  54  may be any of the removable pins taught in the prior art.  
         [0075]    Another embodiment of the present invention, is best shown in FIGS.  15 - 17 . Tool driver  200  includes a driver shaft  202  with a first partial boss  204  at one end thereof; a second partial boss  206 ; a shaft spring  208 ; a driver sleeve  210 ; and a bias button  212 .  
         [0076]    Driver shaft  202  has a longitudinal shaft axis  213  and includes first partial boss  204  defining one end thereof and a tool collect  214  defining the other. First partial boss  204  has first latch member  216 , a diametrically opposed second latch member  218  and a substantially circular central boss zone  220  therebetween. First latch member  216  and second latch member  218  include a first latch groove  222  and a second latch groove  224 , respectively, sized and adapted to rotatably receive and retain a portion of diametral or mounting bar  60  (FIG. 1) of tool  78 . Advantageously, first latch groove  222  and second latch groove  224  are substantially parallel to each other and are substantially orthogonal to shaft axis  213 .  
         [0077]    Meanwhile, central boss zone  220  is sized and adapted to receive central disc  134  associated with diametral bar  60 . First latch member  216  and second latch member  218 , in addition to receiving respective portions of diametral bar  60 , are configured to aid in the centering of central disc  134  on central boss zone  220  and thus in keeping central disc  134  substantially coaxial with shaft axis  213 .  
         [0078]    Second partial boss  206  has a first boss portion  226 , an oppositely directed second boss portion  228  and a primary boss bore  230 , primary boss bore  230  slidably accommodating driver shaft  202  therein. First boss portion  226  includes an inwardly tapered first extension member  232  and a diametrically opposed, inwardly tapered second extension member  234 .  
         [0079]    First extension member  232  and second extension member  234  are configured to coact with first latch member  216 , second latch member  218  and central boss zone  220  of first partial boss  204  so as to form a bayonet latch mechanism  236 , as best seen in FIGS. 16 and 18. Bayonet latch mechanism  236  has an axially extending, inwardly tapered latch bore  238  therein. Latch bore  238  extends coaxially from central boss zone  220  of first partial boss  204  and is configured to receive central disc  134  of diametral bar  134  and to thereby center tool  78  on driver shaft  202  relative to shaft axis  213 . Another feature related to bayonet latch mechanism  236  is that first extension member  232  and second extension member  234  are configured for releasably locking diametral bar  60  in place, once such diametral bar  60  is rotated into both first latch groove  222  and second latch groove  224 .  
         [0080]    The interior of second boss portion  228  of second partial boss  206  is separated from first boss portion  226  thereof by primary boss bore  230 . Second boss portion  228  has a spaced interior boss surface  240  that is spaced from and substantially parallel to driver shaft  202 . An interior boss stop portion  242  is located at the junction of primary boss bore  230  and spaced interior boss surface  240 , interior boss stop portion  242  advantageously being substantially orthogonal to driver shaft  202 .  
         [0081]    Shaft spring  208  is slidably mounted on driver shaft  202 , at least a substantial portion of which is positioned between driver shaft  202  and spaced interior boss surface  240 . Shaft spring  208  has a first spring end  244  and a second spring end  246 . As seen from FIG. 16, first spring end  244  is biased against interior boss stop portion  242 .  
         [0082]    Driver sleeve  210  is slidably mounted on driver shaft  202 , driver sleeve  210  having a sleeve operative position  248  relative thereto. Driver sleeve  210  includes a distal first sleeve end surface  250  and a distal second sleeve end surface  252 . When sleeve operative  248  is assumed, first sleeve end surface  250  is held in contact with second spring end  246  of shaft spring  208  by the action of bias button  212  against second sleeve end surface  252 . Further, driver sleeve  210  has a first sleeve end portion  254  and a second sleeve end portion  256  adjacent first sleeve end surface  250  and second sleeve end surface  252 , respectively. Advantageously, at least first sleeve end portion  254  is sized and configured to be received between driver shaft  202  and spaced interior boss surface  240 , thus permitting first sleeve end surface  250  to be more stably positioned against second spring end  246 .  
         [0083]    Bias button  212 , as best seen in FIG. 19, is positioned within driver shaft  202  and biased so as to normally protrude therefrom. The position of bias button  212  is chosen such that second sleeve end surface  252  is immediately adjacent thereto when driver sleeve  210  is in sleeve operative position  248 . Thus, bias button  212  is configured for releasably maintaining driver sleeve  210  in sleeve operative position  248 . As seen from FIGS. 17 and 19, bias button  212  includes a movable button member  258  and a set screw  260  interconnected with a bias spring  262 .  
         [0084]    By the invention, there is provided a new and improved tool driver which can be used with rotary tools of all types, including acetabular cups, patella cutters, reamers and the like. The new and improved tool driver of the invention holds rotary tools coaxially of the longitudinal axis with preciseness such that all of the cutting edge of the rotary tools function as designed. The new and improved tool driver of the invention can be utilized with rotary tools of all sizes and can be used with rotary tools of the type which collect milled bone tissue and other debris for use as filler. The new and improved tool driver and the tools of the invention can be easily cleaned, sterilized and reused, are easy and convenient to use, and can be manufactured without holding any close tolerances and yet achieve exact coaxial rotation of the rotary tool.  
         [0085]    While a specific embodiment of the invention has been shown and described herein for purposes of illustration, the protection afforded by any patent which may issue upon this application is not strictly limited to the disclosed embodiment; but rather extends to all structures and arrangements which fall fairly within the scope of the claims which are appended hereto: