Abstract:
A cutting accessory for use with a powered surgical tool. The accessory includes a drive shaft to which an outer hub is attached. Internal to the outer hub is a self-contained transponder formed from an RFID chip and a coil of electrical conductor embedded within a solid substrate or encapsulated within a plastic enclosure. The transponder wirelessly communicates one or more pieces of information concerning the identity and operation of the accessory to the surgical tool when the accessory is attached to the surgical tool.

Description:
[0001]    This application is a divisional of U.S. Ser. No. 10/782,374 filed Feb. 19, 2004, which is a continuation-in-part of U.S. patent application Ser. No. 10/319,300, filed Dec. 13, 2002, which issued as U.S. Pat. No. 7,237,990, issued Jul. 3, 2007, which is a continuation-in-part of U.S. patent application Ser. No. 10/214,937, filed Aug. 8, 2002. The contents of the above-listed priority applications are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention is related generally to a surgical cutting accessory for use with a powered surgical tool system and, more particularly, to a surgical cutting accessory with an RFID chip that contains data regarding the operation of the cutting accessory. 
       BACKGROUND OF THE INVENTION 
       [0003]    Endoscopic surgical procedures are routinely performed in order to accomplish various surgical tasks. In an endoscopic surgical procedure, small incisions, called portals, are made in the patient. An endoscope, which is a device that allows medical personnel to view the surgical site, is inserted in one of the portals. Surgical instruments used to perform specific surgical tasks are inserted into other portals. The surgeon views the surgical site through the endoscope to determine how to manipulate the surgical instruments in order to accomplish the surgical procedure. An advantage of performing endoscopic surgery is that, since the portions of the body that are cut open are minimized, the portions of the body that need to heal after surgery are likewise reduced. Moreover, during an endoscopic surgical procedure, only relatively small portions of the patient&#39;s internal organs and tissue are exposed to the open environment. This minimal opening of the patient&#39;s body lessens the extent to which a patient&#39;s organs and tissue are open to infection. 
         [0004]    The ability to perform endoscopic surgery is enhanced by the development of powered surgical tools especially designed to perform endoscopic surgical procedures. One such tool, for example, is sold by the Applicant&#39;s Assignee under the trademark HUMMER TPS. This tool is in the form of a cylindrical handpiece designed to be held in the hand of the surgeon. Internal to the handpiece there is a motor. A front end of the handpiece is provided with a coupling assembly for releasably holding a cutting accessory. The types of cutting accessories that are attached to these handpieces include edgers, resectors, planers and burrs. Integral with the motor and coupling assembly is a means for transmitting the rotary power developed by the motor to the cutting accessory. 
         [0005]    The handpiece also has a suction conduit. This is because, in an endoscopic surgical procedure, irrigating fluid is introduced into the surgical site. This fluid serves as transport media for removing tissue and debris from the surgical site. In order to remove the irrigating fluid, and the material in the fluid, a suction path is provided through the cutting accessory and the handpiece. A suction pump is connected to the handpiece to provide the suction force needed for drawing the fluid and material away from the surgical site. In order to control the suction flow through the cutting accessory and the handpiece, the handpiece is provided with a manually operated valve. Thus, with a single handpiece, a surgeon both manipulates the cutting accessory and controls the suction of material away from the surgical site. 
         [0006]    While current endoscopic surgical tool systems have proven useful, there are some disadvantages associated with their construction. Some of these disadvantages are associated with the coupling assemblies integral with the handpieces. For example, many coupling assemblies are provided with release levers that a surgeon or an assistant pivots to place the coupling assembly in a release state wherein a cutting accessory can be removed from the handpiece. Some coupling assemblies are provided with coupling assemblies that not only must be placed in the release state to remove a cutting accessory, but must also be placed in the release state in order to couple a cutting accessory to the handpiece. Requiring medical personnel to perform this step can add to the overall time it takes to remove and replace cutting accessories. 
         [0007]    Moreover, often a coupling assembly comprises numerous components. Providing these components and arranging them together to form a functional coupling assembly adds to the overall cost of providing the handpiece to which the coupling assembly is attached. Another disadvantage associated with providing a coupling assembly that has numerous components is that, the large number of components increases the possibility that, due to the failure of one component, the whole assembly will malfunction. This is especially true when a system is provided with a large number of moving components. 
         [0008]    Also, as discussed in application Ser. No. 10/214,937, one of the applications from which this application claims priority and which is incorporated herein by reference, recently there has been an interest in providing surgical tool systems that allow data to be inductively transferred between the handpiece and the complementary cutting accessory. This system requires the placement of a coil in the distal end, the front end, of the handpiece so that there can be inductive signal transfer between it and a complementary coil in the adjacent proximal end of the associated cutting accessory. This means that, not only must the front end of the handpiece contain the components forming a coupling assembly, it must also have a space in which a coil can be housed. Given the components that comprise some coupling assemblies, the only way both goals can be accomplished is to increase the overall length of the handpiece. This may require lengthening of the proximal end of the complementary cutting accessory, the end fitted in the handpiece. This handpiece lengthening can increase the overall size and weight of the handpiece. These increases run contrary to one goal of modern surgical tool design. This goal being that, to facilitate ease of use of a surgical tool, its size should be kept as small as possible and its weight as low as possible. 
       SUMMARY OF THE INVENTION 
       [0009]    This invention relates generally to a new powered surgical tool system that includes a handpiece which accepts and powers a variety of accessories. Removably secured within each of the accessories is a transponder that wirelessly communicates identification and/or operational information concerning the accessory to the handpiece. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The invention is pointed out with particularity in the claims. The above and further advantages may be better understood by reference to the following description taken in conjunction with the accompanying drawings, in which: 
           [0011]      FIG. 1  is a perspective view of an endoscopic surgical handpiece of this invention that depicts a complementary cutting accessory secured to the handpiece; 
           [0012]      FIG. 2  is a cross-sectional view of the distal end of the handpiece to which a cutting accessory is attached; 
           [0013]      FIG. 3  is a cross-sectional view of the components forming the coupling assembly of this invention; 
           [0014]      FIG. 4  is an exploded view of the coupling assembly; 
           [0015]      FIG. 5  is a longitudinal cross-sectional view of the coupling assembly collet; 
           [0016]      FIG. 6  is a lateral cross-sectional view of the coupling assembly collet taken along line  6 - 6  of  FIG. 5 ; 
           [0017]      FIG. 7  is a perspective view of the locking ring and release button; 
           [0018]      FIG. 8  is a cross-sectional view of the locking ring and release button; 
           [0019]      FIG. 9  is a plan view of the outer hub of the cutting accessory of this invention; 
           [0020]      FIG. 10  is a perspective view of the coil seal of the cutting accessory; 
           [0021]      FIG. 11  is a cross-sectional view of the coil seal of the cutting accessory; 
           [0022]      FIG. 12  is a perspective view of the cutting accessory tag assembly; 
           [0023]      FIG. 13  is a perspective view of an alternative accessory tag assembly; 
           [0024]      FIG. 14  is a cross-sectional view of the accessory tag assembly of  FIG. 13  which illustrates one potential method of producing the accessory tag assembly. 
           [0025]      FIG. 15  is a cross-sectional view of one embodiment of the accessory tag assembly depicted in  FIG. 13 ; 
           [0026]      FIG. 16  is a cross-sectional view of another embodiment of the accessory tag assembly depicted in  FIG. 13 ; 
           [0027]      FIG. 17  is a cross-sectional view of an alternative means for securing the accessory tag assembly in the outer hub; 
           [0028]      FIG. 18  is a diagrammatic illustration of how a number of accessory identification assemblies of this invention may be batch loaded with data; and 
           [0029]      FIG. 19  depicts how there are different fields containing different types of data in the RFID chip of the accessory identification assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    The surgical tool system  18  of this invention, as seen in  FIGS. 1 and 2 , includes an endoscopic handpiece  20 , sometimes called a surgical tool. A complementary cutting accessory  22  is attached to the handpiece  20 . The handpiece  20  includes a generally cylindrical, elongated housing  24 . The distal end of the housing  24  is formed with a bore  26  for receiving the proximal end of the cutting accessory  22 . (Throughout this document, “distal” is understood to be away from the face of the surgeon holding the handpiece  20 ; “proximal” is understood to mean towards the face of the surgeon.) A motor  28 , depicted in phantom, is disposed inside the housing  24 . A rotating output shaft  30 , which is connected to the motor  28  for actuation by the motor, is disposed inside bore  26 . A coupling assembly  32  is mounted to the front end of the housing  24  for removably holding the cutting accessory  22  to the handpiece  20 . 
         [0031]    The cutting accessory  22  includes a drive hub  34  that releasably engages the output shaft  30 . For the purposes of this invention, the exact geometry of the output shaft  30  and drive hub  34  that facilitate the releasable engagement of these components is not relevant. By way of example though, in the depicted version of the invention, a drive pin  36  extends through the distal end of motor output shaft  30 . The drive hub  34  is formed to have a slot  37  that extends forward from the proximal end of the hub. When the cutting accessory  22  is fitted in handpiece bore  26 , the shaft drive pin  36  seats in the drive hub slot  37 . The seating of the drive pin  36  in the drive hub slot  37  causes the drive pin to impart the rotational moment of the output shaft  36  to the drive hub  34 . 
         [0032]    The cutting accessory  22  includes a static outer hub  38  that surrounds the drive hub  34  that is held in housing bore  26  by the coupling assembly  32 . A tubular drive shaft  40  is integrally attached to the drive hub  34  and extends forward, distally from the drive hub  34  through the outer hub  38  and forward from the handpiece  20 . A cutting head, such as a burr or open window shaver, shaver illustrated, is attached to or integrally formed with the distal end of the drive shaft  40 . A tubular-shaped outer shell  42 , sometimes called the outer housing, extends forward from the outer hub  38  and surrounds the drive shaft  40 . The extent to which the distal end of the outer shell  42  surrounds the drive shaft  40  cutting head is a function of the design of the particular cutting accessory  22 . It should be further understood that the distal end of the drive shaft  40  is provided with an opening  41  through which suction is drawn from the surgical site. 
         [0033]    When the surgical tool system  20  of this invention is employed to perform a surgical procedure, irrigating fluid is introduced into the site through the distal end of the cutting accessory. This fluid may be flowed to the site through the annular space between the drive shaft  40  and the inner wall of outer shell  42 . Alternatively, the fluid is introduced through a separate cannula that opens into the surgical site. Suction is drawn through the handpiece  20  and drive shaft  40  of the accessory  22  to remove irrigating fluid and the material entrained in the irrigating fluid. 
         [0034]    Handpiece housing  24  is formed with an elongated bore  50  that extends axially through the housing. The distal end of bore  50  is located rearwardly from the proximal portion of the bore  26 . While not seen in the drawings, it should be understood that bore  50  is the space in which the handpiece motor  28  is seated. The distal end of housing  24  is formed to have a ring-shaped head  52  that defines a first counterbore  54  that is coaxial with bore  50 . Immediately proximal to head  52 , housing  24  has a second counterbore  55  also coaxial with bore  50 . Second counterbore  55 , which has a diameter between that of bore  50  and the first counterbore  54 , is a transition bore between bore  50  and the first counterbore  54 . A suction bore  56  branches off of bore  50 . Suction is drawn through the cutting accessory drive shaft  40  through the suction bore  56 . Partially seen in  FIG. 2  is a valve bore  58  that intersects the suction bore  56 . A valve (not illustrated) is disposed in the valve bore  58  for regulating the suction flow through the cutting accessory  22  and the handpiece  20 . 
         [0035]    The coupling assembly  32 , now described primarily by reference to  FIGS. 2 ,  3  and  4 , is secured to the distal end of the handpiece housing  24 . Specifically, the coupling assembly  32  includes a generally ring-shaped collet  60  that is secured to the housing  24 . Collet  60  is the portion of the handpiece  20  that defines bore  26 . A locking ring  62  is movably disposed in the collet  60 . A cover plate  64  is fitted over the collet  60  and locking ring  62  so as to hold the locking ring to the collet. A wave spring  66  seated between the collet  60  and the locking ring  62  biases the locking ring into a locked state in which the ring holds the cutting accessory outer hub  38  in handpiece bore  26 . 
         [0036]    The collet  60 , is formed of a plastic able to withstand the rigors of steam sterilization, such as a polyphenylsulfone plastic, one such plastic being sold under the trademark RADEL by Amoco Chemicals/British Petroleum. In some versions of the invention, the plastic forming the collet  60  is 15 to 30% carbon filled PEEK. The collet  60 , as seen in detail in  FIGS. 4 ,  5  and  6 , includes a sleeve-shaped base  70 . Extending distally from base  70 , the collet  60  has a head  72  that has an outer diameter greater than the outer diameter of the base  70 . Bore  26  extends axially through collet  60 , from the distal end of head  72  to the proximal end of base  70 . Collet  60  is further formed so that head  72 , has an arcuate-shaped recessed section  74  that surrounds between 190° and 250° of the outer circumference of the collet. In more preferred versions of the invention, recessed section  74  surrounds between 230° and 240° of the outer circumference of head  72 . Within recessed section  74 , collet head  72  is further shaped to have a laterally extending slot  76  that opens into bore  26 . Immediately proximal to slot  76 , the collet head  72  is shaped so as to have two small flat surfaces  78  that angle away from an apex that is parallel with the longitudinal axis of the collet  60 . Collet head  72  is further formed so that within each flat surface  78  there is a groove  80  with a flat base surface recessed from the associated flat surface  78 . 
         [0037]    Collet  60  is formed so that within head  72  and the adjacent distal section of base  70  there is an inner wall  82  with a constant diameter circular cross-sectional profile that defines the distal portion of bore  26 . Within head  72 , collet  60  is further formed so that there is an arcuate groove  84  that extends inwardly of wall  82 , away from the center axis of the collet. Groove  84  is diametrically opposite the arcuate section of collet head  72  inscribed by slot  76 . Collet  60  is further shaped to have two diametrically opposed slots  86  that extend proximally away from the distal end opening of head  72  and terminate immediately forward of the proximal end of the head. Slots  86  are diametrically opposed from each other. A first one of the slots  86  intersects slot  76 ; the opposed slot  86  intersects groove  84 . It should be understood that groove  84  has a depth greater than that of the intersecting slot  86 . As will be understood hereinafter, the greater depth of groove  84  is designed to provide space so that the adjacent section of the locking ring  62  can extend into the portion of groove  84  located below the intersecting slot  86 . 
         [0038]    Collet  60  is further formed to have a skirt  88  that extends proximally from the proximal end of head  72  and circumferentially surrounds the adjacent distal end of base  70 . More particularly, it will be noted that skirt  88  is spaced away from the outer surface of the portion of the base surrounded by the skirt so as to define an annular space  90  between these two components of the collet  60 . Skirt  88  is shaped so that around its outer surface there are two spaced apart, circumferentially extending grooves  91 . 
         [0039]    The collet  60  is shaped so that the portion of base  70  that extends rearwardly from head  72  has both a generally constant outer diameter and wall thickness. The proximal end of the base  70  has an annular tail section  92  that is stepped inwardly from the more distal portions of the base. More particularly, there is a stepped surface  94  along the outside of the base between the distal portions and tail section  92  that has a curved cross-sectional profile. Also, collet  60  is shaped so that inside base  70 , immediately distal to tail section  92 , there is an inner wall section  96 , immediately proximal to wall  82 , with an inwardly curved profile. 
         [0040]    Locking ring  62  is formed of a sterilizable metal, such as stainless steel. The locking ring  62 , now described by reference to  FIGS. 4 ,  7  and  8 , is shaped to define a center opening  102  with a shape that is oval. Locking ring  62  is further formed to have a lip  104  that projects into opening  102  from one of the curved ends of the ring. Lip  104  provides the end of the ring  62  with which it is integral a taper such that the overall wall thickness of the ring increases along a line that extends proximally away from the distal-facing side of the ring. 
         [0041]    A release button  106  is integrally formed with the locking ring  62  so as to be located on the side of the ring opposite the side with which lip  104  is integral. More specifically, release button  106  both subtends the end of the ring to which the button is mounted and extends proximally away from the ring. A slot  108  is formed in the portion of the ring  62  to which release button  106  is attached. Slot  108  opens into center opening  102  and has the same cross-sectional profile as the slots  86  formed in collet  60 . 
         [0042]    As part of the assembly of handpiece  20  of this invention, collet  60  is attached to handpiece housing  24 . Specifically, the collet base  70  seats in the second counterbore  55 , as seen in  FIG. 2 . Prior to the attachment of the collet to the handpiece housing  24 , a coil  110  is seated in annular space  90 . The coil, which may be a wire wrap or a conductive trace formed on a flexible substrate, is the coil used to facilitate inductive signal transfer to/from a radio frequency identification device (RFID) chip  170  disposed in the accessory outer hub  38  ( FIG. 12 ). Coil  110  is connected to downline signal processing components through conductors  114  that extend through a longitudinally extending bore  113  formed in the handpiece housing  24 . 
         [0043]    An O-ring  116  extends around the collet base tail section  92 . O-ring  116  abuts the stepped surface of housing  24  that defines the transition from bore  50  to second counterbore  55 . More particularly, the stepped surface of housing  24  is formed to define a groove  118  with an arcuate profile in which O-ring  116  seats. The inner portion of O-ring  116  is seated against the curved collet step surface  94 . 
         [0044]    Collet  60  is secured to handpiece housing  24 , in part, by an adhesive capable of withstanding the rigors of sterilization, such as a silicone adhesive. The adhesive is placed between the opposed surfaces of housing head  52  and collet skirt  88 . A fraction of the adhesive collects in the grooves  91  that extend around the outer surface of skirt  88 . Upon the curing of the adhesive in the grooves, the adhesive forms two O-rings  119  between the housing  24  and the collet  60 . The O-rings  119  prevent fluid flow from the ambient environment moving through the handpiece-collet interface. 
         [0045]    Removable set screws, not illustrated, further hold the collet  60  to the distal end of the housing  24 . These set screws extend through threaded bores  117  formed in the distal end of the handpiece housing  24  (one bore shown in  FIG. 1 ). The ends of the set screws set in recesses  120  formed in the outer surface of collet base  70  (one recess shown in  FIG. 4 ). 
         [0046]    Locking ring  62  is slip-fitted in collet slot  76 . More particularly, the locking ring  62  is attached to the collet  60  so that the end of the ring with which lip  104  is integral seats in groove  84 . When the locking ring  62  is fitted to the collet  60 , the release button extends rearwardly, over flat surfaces  78  and the adjacent portion of the recessed section  74 . 
         [0047]    The wave spring  66  is disposed between the collet head  72  and the release button  106 . Specifically, each end of the wave spring  66  is seated in a separate one of the grooves  80  formed in the collet head  72 . The topmost crest portion of the wave spring is fitted against a recessed surface  122  formed in the release button  106  immediately proximal to locking ring  62 . 
         [0048]    Cover plate  64  is snap-secured in the recess  74  formed in the collet head. The cover plate  64  has an arcuate shape corresponding to that of the collet recess  74 . There is an opening  124  in the center of the cover plate  64  through which release button  106  extends. In the illustrated version of the invention, the cover plate  64  has a center section  126  with greater wall thickness than that of the surrounding ends. Opening  124  is formed in the center section  126 . 
         [0049]    The static outer hub  38 , which is formed of rigid plastic, is now described by reference to  FIGS. 9 ,  10  and  11 . The outer hub  38  is constructed to have a sleeve-shaped base  130 . The base  130 , it will be observed, is formed with two diametrically opposed, generally rectangularly shaped openings  132 . Extending forward from base  130  and formed integrally therewith is a substantially solid head  133 . While head  133  is substantially solid, the outer hub  38  is formed so that a bore  134  extends axially through the head. Outer shell  42  is mounted in bore  134  in any conventional manner to extend forward from head  133 . In the depicted version of the invention, the outer surface of hub head  133  is provided with threading, not identified. The threading is provided to facilitate the releasable screw securement of the cutting accessory  22  to a cannula fitted in the portal formed in the patient and directed towards the surgical site. 
         [0050]    Outer hub  38  is further formed to have two diametrically opposed ears  135  that are integrally formed with, and extend outwardly from, the base  130 . Each ear  135  is formed so as to have a relatively short proximally-directed face  136  that extends laterally away from the longitudinal axis of the hub  38 . Distal to face  136 , each ear  135  has a parallel distally directed face  138 . A side surface  137  extends between the opposed faces  136  and  138  of ear  135 . Each ear is formed such that the side surface  137  has a rise or taper at least adjacent the proximally-directed faces  136  such that the overall thickness of the ear  135  increases moving away from face  136 . In some versions of the invention, the ears  135  are formed so that side surfaces  137  have a profile that, extending from the proximally-directed faces  136 , is curved or arcuate. 
         [0051]    In the depicted version of the invention, laterally extending grooves  131  are formed in the distal end of the outer hub base  130 . The grooves  131  extend circumferentially around the base. Two longitudinally offset, parallel sets of grooves  131  are shown. Each set of grooves consists of a set of spaced apart grooves. The presence of grooves  131  are in response to the plastic manufacturing process used to produce the outer hub base  130 . Specifically, plastic molded parts typically shrink as they cool during the latter stages of the manufacturing process. To prevent the surface of the plastic molded part from distorting due to non-uniform shrinkage, grooves are frequently provided in the plastic part. The grooves function, in layman terms, as a “reduce sink” that allows the remainder of the plastic part to shrink uniformly, thereby preventing surface distortions. Accordingly, grooves  131  are provided to facilitate the injection molding of the outer hub base  130 . 
         [0052]    A generally tube-shaped coil seal  139  is disposed in hub base  130 . Coil seal  139  is formed from flexible sterilizable material. In one version of the invention, coil seal  139  is formed from a silicon rubber that has 55 Shore A durometer hardness. The coil seal  139  is shaped to have a first end section, distal end section  140 , that has a constant outer diameter and inner diameter. Extending proximally from the distal end section  140 , the coil seal  139  has a main section  142 . Main section  142  has the same inner diameter as distal end section  140  and a narrower outer diameter. The coil seal  139  is further formed to define a generally rectangular recess  144  in the outer surface of main section  142 . Located proximal to main section  142 , the coil seal  139  has a second end section, proximal end section  146 . The inner and outer diameters of proximal end section  146  are the same as those of the distal end section  140 . The proximal end section  146  of the coil seal  139  is further formed to have two diametrically opposed lock tabs  148 . Each lock tab  148  extends radially outwardly from the outer surface of the proximal end section  146 . The proximal end section  146  also has two diametrically opposed stop tabs  150  that extend inwardly from the inner wall of the section. In the depicted version of the invention, each stop tab  150  is radially aligned with a separate one of the lock tabs  148 . 
         [0053]    Coil seal  139  is further formed to have a tail section  152  that extends rearwardly from the proximal end section  146  and that forms the proximal end of the seal. The tail section  152  is formed to define two annular spaced apart ribs  154  and  156  that extend circumferentially around coil seal  139 . Both ribs  154  and  156  extend beyond the outer diameter of the seal locking section  146 . In the depicted version of the invention, the diameter of the circle subtended by the more proximal of the two ribs, rib  156 , is less than the diameter subtended by the other rib, rib  154 . Tail section  152  is further formed to have an inner wall that is outwardly flared. 
         [0054]    When a cutting accessory  22  of this version of the invention is assembled, an RFID chip  170 , seen in  FIG. 12 , is seated in seal recess  144 . A coil  172  connected to the chip  170  is disposed over the reduced diameter outer surface of seal main section  142 . In the version of the invention depicted in  FIG. 12 , the chip  170  is mounted on a small flex circuit  171 ; the coil  172  is a conductive trace formed on the flex circuit  171 . After manufacture of the flex circuit  171 , the flex circuit, with the chip  170  mounted thereon, is wrapped in a cylinder over seal main section  142  so that the chip seats in recess  144 . 
         [0055]    The RFID chip-coil-and-seal assembly is fitted in hub base  130 . Consequently, both the RFID chip  170  and coil  172  are disposed between the inner wall of the hub base and the outer surface of coil seal  139 . Owing to the relative dimensions of outer hub  38  and coil seal  139 , the outer surfaces of the seal&#39;s distal end and proximal end sections  140  and  146 , respectively, press against the inner wall of the hub base  130 . This contact forms a seal around chip  170  and coil  172 . Thus, in some versions of the invention, there may not be a need to employ an adhesive or other chemical to provide a moisture barrier around the chip  170  and coil  172 . 
         [0056]    As part of the insertion of the coil seal  139  into the outer hub  38 , lock tabs  148  are seated in hub base openings  132 . The seating of the lock tabs  148  in openings  132  holds the coil seal  139  to the outer hub  38 . When the coil seal  139  is so attached to outer hub  38 , tail section ribs  154  and  156  are located proximal to the proximal end opening of the hub. 
         [0057]    As described above, the drive hub  34 , now described by reference to  FIG. 2 , transfers the rotary motion of the handpiece output shaft  30  to the cutting accessory drive shaft  40 . The drive hub has a stem  173  that is the proximal end portion of the drive hub. Stem  173  is the portion of the drive hub  34  that is formed with the geometric features that facilitate the coupling of the hub to the motor output shaft  30 . Located within the base of the bore within stem  173  there is a coil spring  169  with a conical profile. 
         [0058]    Extending forward from stem  173 , the drive hub  34  has a neck  174  that extends into the proximal end opening of the outer hub  38 . In the depicted version of the invention, neck  174  has a diameter less than that of stem  173 . A head  176  located forward of the neck  174  forms the distal end of the drive hub  34 . Head  176 , it will be observed, has a larger diameter than the adjacent neck  174 . More specifically, the drive hub  34  is formed so that neck  174  has a diameter less than that of the open section defined by the inner surfaces of coil seal stop tabs  150 . In contrast, drive hub head  176  has a diameter that is slightly greater than the opening defined by the coil seal stop tabs  150 . For example, in one version of the invention, the neck  174  of the drive hub  34  has an outer diameter of 0.31 inches and head  176  has a diameter of 0.344 inches. In this version of the invention, the open section of the bore defined by the coil seal tabs  150 , once the coil seal  139  is seated in the outer hub  38  and slightly compressed, is between 0.33 and 0.34 inches. 
         [0059]    A bore  177  extends from the distally directed front face of the drive hub head  176 , through the head  176  and partially through neck  174 . The proximal end of the drive shaft  40  is secured in the distal portion of bore  177  by any conventional means. The drive hub  34  is further formed to have a suction port  180  on one side of the neck  174  that curves into, and is in fluid communication with, the proximal end of bore  177 . Suction port  180  is the opening in the drive hub  34  through which suction is drawn. 
         [0060]    The cutting accessory  22  is assembled by inserting the drive shaft  40  through the outer hub  38  and into the outer shell  42 . When the cutting accessory  22  is so assembled, the drive hub and drive shaft subassembly are moved past coil seal  139  in hub bore  134 . Owing to the dimensioning of the components, the drive coupler head  176  abuts the coil seal stop tabs  150 . Owing to the compressibility of the material from which the coil seal  139  is formed, a small amount of force compresses the stop tabs  150  to allow the complete insertion of the drive coupler and rotating shaft. After assembly, if the cutting accessory  22  is held vertically, the drive hub head  176  will drop so as to abut stop tabs  150 . Thus, the stop tabs  150  prevent gravity, without any additional force, from causing the drive hub  34  and drive shaft  40  to drop out of outer hub  38 . 
         [0061]    In the depicted version of the invention, a washer  183  is shown surrounding the portion of the drive shaft  40  located immediately forward of the drive hub  34 . Washer  183  is thus sandwiched between the distally-directed face of the drive hub  34 , and the adjacent proximally directed recessed face of the outer hub  38 . Washer  183  is provided with some cutting accessories  22 , such as burs, as both a spacer and to reduce the friction contact between the drive and outer hubs  34  and  38 , respectively. 
         [0062]    The cutting accessory  22  is secured to the handpiece  20  by inserting the drive and outer hubs  34  and  38 , respectively, into the open end of collet bore  26 . The outer hub ears  135  are inserted in collet slots  86 . As the outer hub  34  is seated in opening  26 , the arcuate side surface  137  of the ear  135  adjacent the locking ring lip  104  presses against the lip. Owing to the complementary tapers of lip  104  and the adjacent ear  135 , the movement overcomes the force of wave spring  66  that urges that lip into the portion of groove  84  that intersects the contiguous slot  86 . Thus, the lip  104 , and the adjoining arcuate section of the locking ring  62  are pressed into collet groove  84  so that the ear  135  can pass over the lip. 
         [0063]    Once the outer hub ear  135  passes over the locking ring lip  104 , the wave spring  66  urges the lip back into the position in which the lip is within the portion of groove  84  that intersects the contiguous slot  86 . When the locking ring  62  is so seated, lip  104  abuts the distally-directed face  138  of the ear  135  to hold the outer hub  38  and the whole of the cutting accessory  22  to the handpiece  20 . When the coupling assembly  32  is in this state, the assembly is considered in the locked state. 
         [0064]    While not part of this invention, it should be understood that, owing to the geometry of the proximal end of the drive hub  34 , the seating of the cutting accessory  22  in opening  26  causes the drive hub  34  to engage the motor output shaft  30 . When the drive hub  34  is so seated, the narrow diameter end of spring  169  presses against the distal facing face of the motor output shaft  37 . Spring  169  thus pushes the drive hub  34  forward. 
         [0065]    When the cutting accessory  22  is fitted in the handpiece opening  26 , ribs  154  and  156  abut the tapered inner wall section  96  of collet base  70 . Ribs  154  and  156  thus function as a seal that prevents leakage from the suction channel to the outside environment. 
         [0066]    As a result of the coupling of the cutting accessory  22  to the handpiece  20 , accessory coil  172  is disposed in the space surrounded by handpiece coil  110 . The coils  110  and  172  are thus in close enough proximity to each other so that there is inductive coupling of signals between the coils. 
         [0067]    During the course of a surgical procedure, a surgeon may want to replace the cutting accessory  22  attached to the handpiece  20  with a different cutting accessory. The installed cutting accessory is removed by the downward depression of the release button  106 . This action causes a like downward movement of the locking ring  62  so that lip  104  retracts into the portion of groove  84  below the contiguous slot  86 . As a result of this motion, lip  104  moves clear of the adjacent outer hub ear  135 . Once the locking ring  62  is so positioned, the coupling assembly  32  is referred to as being in the release state. The transition of the coupling assembly  32  to the release state allows the spring  169 , which is previously compressed, to expand. Since the distal end of the spring  169  is disposed against the drive hub  34 , the spring pushes the drive hub  34 , and therefore the outer hub  38 , a short distance forward of the open end of bore  26 . Consequently, it becomes a simple task to manually pull the cutting accessory  22  from the handpiece  20 . 
         [0068]    Once the cutting accessory  22  is extracted from the bore  26  so that the outer hub ear  135  clears the locking ring  62 , the pressure on the handpiece can be released without adversely effecting the removal of the cutting accessory. The replacement cutting accessory  22  is then inserted into the handpiece  20 . As with the insertion of the first cutting accessory  22 , there is no need for the medical personnel to depress the release button  106  in order to secure the new accessory to the handpiece  20 . 
         [0069]    The coupling assembly  32  of this invention is constructed out of just a few components. Only two of the components, the locking ring  62  and the wave spring  66 , move. Thus, given the relatively small number of components incorporated into this coupling assembly, and the fact that only two of the components move, it is relatively economic both to provide the parts of this assembly and to put them together to manufacture the completed assembly. 
         [0070]    The coupling assembly  32  of this invention is further constructed so that it does not have to be placed into the release mode in order for the assembly to lock a cutting accessory  22  to the handpiece  20  with which the assembly is integral. Collectively, the handpiece  20  and complementary cutting accessory  22  are arranged so that either of the outer hub ears  135  can seat in either of the collet slots  86 . Thus, during the process of fitting the cutting accessory  22  to the handpiece  20 , the accessory does not need to be rotated more than 180° before the accessory is properly aligned to be inserted into the handpiece opening  26 . Both of these features of the invention make it possible for surgical personnel to rapidly fit a cutting accessory to the handpiece with relatively little manipulation or concentration. 
         [0071]    Also, the collet  60  of the described version of the invention is formed from plastic. Thus, since the collet  60  is non-metallic, the collet can readily serve as a housing for coil  110  and not adversely affect the inductive signal transfer between coils  110  and  112 . Also, the material from which the collet  60  is formed is lighter in weight than the aluminum from which the handpiece housing  24  is formed. Thus, by providing a plastic collet, the overall weight of the coupling assembly, and the handpiece  20  to which it is installed, is minimized. The minimization of handpiece weight serves to lessen the fatigue to which a surgeon is exposed as a result of having to hold and manipulate the handpiece for an extended period of time. 
         [0072]    Still another feature of this invention is that the inner wall section  96  of collet  60 , the surface of the collet against which ribs  154  and  156  abut, is curved. Consequently, as soon as there is forward movement of the drive hub  34  out of bore  26 , the surface contact between the ribs  154  and  156  and the collet  60  is broken. The breaking of this contact results in a like break in the friction bond that would otherwise hold the ribs  154  and  156  to the collet. The breaking of this bond means that the kinetic force released by the continued expansion of spring  169  is not applied to overcoming friction bond. Instead this spring force serves to urge the hubs  34  and  38  of bore  26 . 
         [0073]    Another feature of the coupling assembly  32  of this invention is that it houses coil  110 . Thus, in a relatively short overall section of the handpiece, in a section usually less than 1.7 inches or less in length and, more particularly, 1.4 or less inches in length, the handpiece of this invention has both a coupling assembly and a coil that is employed to read and write data into a RFID chip  170  fitted in the cutting accessory  22 . 
         [0074]    Moreover, the locking members that are integral with the cutting accessory  22  of this invention, ears  135 , are, from a manufacturing standpoint, relatively easy to provide. It is a relatively simple task to form the ears  135  during the molding of the outer hub  38 . 
         [0075]    Coil seal  139  of the cutting accessory  22  performs a number of different functions. Specifically, the seal serves as one of the components that protects the RFID chip  170  and coil  172  from the ambient environment. Ribs  154  and  156  of the seal function as a seal around the drive hub  34 . This seal ensures that the suction drawn through the handpiece causes fluid flow from the distal end of the drive shaft  40 , not the surrounding environment. Stop tabs  150 , in combination with the relatively large diameter of the drive hub head  176 , cooperate to prevent the drive hub and drive shaft sub assembly from falling out of the outer hub and outer shell subassembly. 
         [0076]    An alternative assembly for holding an RFID chip  190  and complementary coil  192  in an outer hub  38   a  is now described by reference to  FIGS. 13-17 . In this version of the invention, the RFID chip  190  and a length of electrical conductor, such as coil  192 , are embedded in a substrate or encapsulated in an enclosure to form a transponder or identification module. In the illustrated embodiment of  FIG. 13 , for example, the chip  190  and coil  192  are sealed within a plastic ring  194 . In the present embodiment, the plastic ring  194  is formed from polypropylene which can be sterilized by various methods such as exposure to GAMA radiation or ETO gas. The appropriate size gauge and length of electrical conductor is turned or looped to form the wire coil  192 , which is subsequently wrapped in one section of the ring  194 . 
         [0077]    Various methods can be utilized to produce the above-discussed transponder or identification module. One such method is to insert the chip and coil assembly into a previously molded enclosure and then seal the enclosure. Consider the example of  FIG. 14 , which is a cross-sectional side view depiction of the plastic ring  194  of  FIG. 13 . The plastic ring  194  is pre-molded to have an annular base  194 A and inner and outer opposed sidewalls,  194 B and  194 C, respectively, that define an interior channel  195  that initially opens sidewardly to the exterior through an annular opening  194 D. The chip  190  and attached coil  192  are inserted into the interior channel  195  through end  194 D. The interior channel  195  of the plastic ring  194  is then closed by filling same with liquid resin potting material  194 E. Alternatively, channel  195  can be sealed off by filling the channel  195  with a sealant, such as silicone. 
         [0078]    Other potential methods of producing the above-discussed transponder or identification module include shellacking, whereby the chip  190  and coil  192  are dipped in a liquid polymer or resin that subsequently hardens, or even possibly by an over-molding or injection-molding process presuming that obstacles, such as potential heat damage to chip  190 , can be resolved. 
         [0079]    As is with most solid state chips, the RFID chip  190  comprises a collection of solid state circuitry  191 A mounted upon a base  191 B. Depending on the length of the base  191 B, which is determined by the chip manufacturer, chip  190  may be of an inappropriate size to be readily embedded or encapsulated in a shaped substrate or enclosure, such as ring  194 , without subjecting the chip  190  to unnecessary stress. 
         [0080]    One way to relieve such stress is to adjust the shape of the base  191 B to better conform with the shape of the substrate or enclosure that the chip  190  is embedded within. Accordingly, in one embodiment of the present invention, the base  191 B of chip  190  is first adjusted before the transponder or identification module is assembled.  FIG. 15  illustrates one such example where the base  191 B is selectively predisposed with one or more curves or bends  191 C in order to relieve stress upon the chip  190 . 
         [0081]    According to another embodiment, stress in the chip  190  can be reduced or prevented by trimming or shortening the base  191 B to a length more appropriate for the size and shape of the substrate or enclosure in which the chip  190  is embedded.  FIG. 16  illustrates one such example where the base  191 B is trimmed in length to better conform with its ring enclosure  194 . 
         [0082]    As illustrated in  FIG. 17 , the plastic ring  194  with embedded RFID chip  190  and coil  192 , is slip fitted into outer hub  38   a . Outer hub  38   a  has the same general outer surface geometry as first described outer hub  38 . Outer hub  38   a  is further formed so that there are two circumferentially extending interior walls  196  and  198  internal to the hub base  130   a  that define the bore  202  that extends axially through the hub base. The interior wall closest to the hub head  133   a , wall  196 , has a diameter that is less then the diameter of the more proximal wall, wall  198 . Thus, walls  196  and  198  define a circumferentially extending and inwardly directed step  204  that extends between the respective walls. 
         [0083]    The outer hub  38   a  and ring  194  are collectively dimensioned so that the ring closely slip fits against interior wall  198 . The distal end of the ring  194  seats against step  204 . 
         [0084]    An annular seal  208  is seated in the proximal open end of hub bore  202  and holds ring  194  in the bore. Seal  208  is formed from the same material from which coil seal  139  is formed. Seal  208  is shaped to have a ring shaped base  210  that is similar in geometry to the proximal end section  146  of seal  139 . Thus, seal base  210  is formed to have lock tabs  212  and stop tabs  214  identical in shape and function to the first described lock tabs  148  and stop tabs  150 . Extending proximally rearwardly from base  210 , seal  208  has a tail section  216  identical in form and function as tail section  152 . 
         [0085]    Seal  208  is further formed so as to have a set of raised bumps (not illustrated) that extend from the distal facing front ring-shaped face of the seal. The raised bumps are the most forward facing surface features of the seal  208 . When the alternative outer hub assembly is assembled, the raised bumps press against the adjacent proximal facing annular surface of ring  194 . 
         [0086]    When the cutting accessory with RFID chip of this embodiment of the invention is assembled, the plastic ring  194  with embedded chip  190  and coil  192  is slip fitted into outer hub bore  202 . The distal end of the ring  194  seats against step  204  formed in the outer hub  38   a . Annular seal  208  is then pressed into hub bore  202 . More specifically, the seal  208  is pressed into the bore until lock tabs  212  extend through hub base openings  132   a . The seal  208  thus holds plastic ring  194  in hub bore  202 . 
         [0087]    In the above-described version of the invention, ring  194  totally encapsulates both RFID chip  190  and coil  192 . This encapsulation prevents fluids from contacting the chip  190  or coil  192  and possibly adversely affecting the operation of these components. Another benefit of this encapsulation is that it physically shields the chip  190  and coil  192  from mechanical shock. Thus, the ring  194  can be handled without having to take excessive care to ensure that contact with the ring damages either the chip or coil. 
         [0088]    Moreover, ring  194  of the above embodiment, representing one example of a substrate or enclosure into which the RFID chip  190  and coil  192  are embedded, encapsulated or sealed, is a separate component from the outer hub  38   a . This means that when the components of this invention are fabricated, one does not have to engage in the process of attaching or embedding the RFID chip  190  and coil  192  into the hub, which can be a relatively costly process. Instead, the potentially less costly process of embedding, encapsulating or sealing the chip and coil in a separate substrate or enclosure, such as the ring  194 , is employed. 
         [0089]    Seal  208 , does more than function as proximal end seal around the outer hub  38   a  and a stop mechanism that prevents the drive hub  34  from falling out of the outer hub. The seal  208  also serves as the member that holds the ring  194  in the outer hub  38   a . Also, it is clear that it is a relatively simple task to fit the seal in the outer hub  38   a  and that such mounting does not require the use of an added adhesive. The above features of the foregoing described version of the invention make it relatively easy to provide the cutting accessory of this version of the invention with the RFID chip  190  and coil  192 . 
         [0090]    Moreover, since the plastic ring  194  protects the RFID chip  190  and coil  192 , a number of these assemblies may be physically packed together, to a density where adjacent rings physically abut. As seen by reference to the diagrammatic representation of  FIG. 18 , this means a large number of chip and coil embedded ring assemblies may be placed at a workstation  220  and simultaneously be loaded with identification data. 
         [0091]    As seen by reference to  FIG. 19 , it should be understood that, upon delivery from the manufacturer, the memory of each RFID chip  190  includes a data field for a serial number  222  and a set of empty data fields represented as fields  224 ,  225  and  226 . The RFID chip  190  and coil  192  are subsequently embedded into a substrate or encapsulated within an enclosure, such as plastic ring  194 . 
         [0092]    After the chip  190  and its associated coil  192  are sealed within a substrate or enclosure to form a transponder or identification module, they are then subjected to batch programming in accordance with the intended purpose of a particular type of cutting accessory. In the batch programming, at the workstation  220 , a single writing device  228  with a single coil  230  simultaneously writes data into fields  224 ,  225  and  226 . Specifically, these data are the data used by the control console to which the handpiece  20  is connected to regulate the actuation of the handpiece motor  28 . The data written into fields  224 ,  225  and  226  indicate such things as: the type of cutting accessory; the initial, preferred minimum and preferred maximum operating speeds of the cutting accessory; authorization codes verified by the control console in order to determine whether or not it is appropriate to actuate the motor; a suggested operating lifetime for the cutting accessory; the type of cutting accessory; and the batch lot in which the cutting accessory was manufactured. 
         [0093]    The above data are identical for each cutting accessory manufactured in a single batch lot. Therefore, these data can be simultaneously written into the RFID chips  190  for each chip within the lot. This eliminates the more time consuming task of having to write the data individually into each chip. Since each chip already has a data field  222  in which a unique identification number is stored, this identification number can be used as the unique identification number for the cutting accessory  22 . 
         [0094]    It should be recognized that the foregoing are descriptions of two preferred versions of the invention and that other versions of the invention may vary from what has been described. For example, while generally the surgical handpiece  20  is discussed in conjunction with a cutting accessory  22 , it should be understood that the transponder or identification module of the present invention may be readily utilized in other types of surgical handpiece accessories, such as, for example, heat-generating devices, light generating devices and sound/mechanical-vibration generating devices. In addition, while the surgical handpiece  20  and accessory  22  are discussed in the above embodiments in relation to endoscopic surgery, use of the invention is not so limited. The components of the system of this invention can also be employed to perform other types of surgical procedures. Handpieces and cutting accessories of this invention may, for example, be designed to perform ENT procedures, spinal procedures and neurological procedures. 
         [0095]    Also, some versions of the invention may not include all features of the described version of the invention. For example, some systems of this invention may not have the coils that are employed to facilitate inductive signal transfer between the handpiece and complementary cutting accessory. In some of these versions of the invention, it may therefore not be necessary to provide the collet as a component separate from the handpiece housing. In these versions of the invention, the locking ring, the wave spring and the cover plate are fitted directly onto the handpiece housing or body. An advantage of this arrangement of the invention is that it even further reduces the number of components that need to be provided in order to construct the handpiece of this invention. 
         [0096]    Similarly, there may be reasons to provide a tool system of this invention with some or all of the features of the coil seal but not to employ the specifically disclosed means for releasably holding the outer hub to the handpiece. Thus, an alternative version of the invention may comprise an elastomeric member attached to the proximal end of the outer hub that includes one or more of the described ribs. This version of the invention may be constructed if the cutting accessory is not provided with an RFID chip. In these versions of the invention, the ribs of these members perform the sealing function of described ribs  154  and  156 . In these versions of the invention, the outer hub may be provided with surface features different from the described ears to facilitate the releasable attachment of the cutting accessory to the handpiece. 
         [0097]    With regard to the ribs  154  and  156 , it should similarly be recognized that their number are exemplary, not limiting. Some versions of the invention may be provided with a single rib, some versions three or more ribs. Also, in the described version of the invention the rib  156  is seated is of smaller outer diameter than rib  154 . This is because the section of the inner wall of the housing against which rib  156  abuts is of smaller diameter than the section against which rib  154  abuts. In alternative versions of the invention, the diameters of these ribs may vary to compensate for like differences in the profiles of the surfaces the ribs are intended to abut. 
         [0098]    Further, it should be recognized that the location of the coil seal lock tabs  148  and the complementary outer hub openings  132  in which the lock tabs are seated may be different from what has been described. Thus, the lock tabs may be integral with the distal end section  140  of the seal. Also, both the end sections of the seal may, in some versions of the invention, be provided with lock tabs. In these versions of the invention it should be understood that the outer hub is formed with longitudinally spaced openings in which the lock tabs are seated. 
         [0099]    In some versions of the invention, it may not even be necessary to provide the lock tabs and complementary outer hub openings in which the lock tabs are seated. In some versions of the invention, it may be possible to provide a seal that is simply compression and/or friction secured into the outer hub bore. In still other versions of the invention, an adhesive may be supplied to bond the seal in the outer hub bore. 
         [0100]    It should similarly be recognized that the geometry and number of the stop tabs  150  may vary from what has been described. For example, in some versions of the invention, instead of providing two tabs, the stop member may be a ring formed of flexible material. The ring thus defines an open section of the outer hub base proximal end opening that has a diameter greater than that of drive hub neck  174  and less than that of the drive hub head  176 . This ring may or may not be provided with slots to facilitate its flexing in order to allow the insertion of the drive hub head into the outer hub proximal end opening. Alternatively, three or more tabs formed of flexible, compressible, or otherwise yielding material, may be provided as stop tabs. 
         [0101]    Also, the number of ears  135  integral with the cutting accessory outer hub  38  may be different from what has been described. In some versions of the invention, it may be desirable to provide a single ear  135 . This version of the invention may be provided when there is a need to position the cutting accessory in a specific rotational orientation relative to the handpiece  20 . In other versions of the invention, it may be desirable to provide the cutting accessory with three or more ears. In these versions of the invention, the collet and locking ring are appropriately shaped to accommodate the seating of the ears that do not abut the lock ring. An advantage of these versions of the invention is that they further reduce the extent to which the cutting accessory  22  needs to be rotated in order to position one ear in the slot  86  where the locking ring will then block the movement of the ear. This also increases the extent to which the rotational orientation of the cutting accessory  22  relative to the handpiece  20  can be selectively set. 
         [0102]    Similarly, it should be understood that the components of the versions of the cutting accessory described in detail may be intermixed as may be appropriate. For example, in some versions of the invention, it may be desirable to embed the RFID chip  190  and coil  192  in ring  194  and place this accessory identification between the inner wall of the outer hub and adjacent outer wall of a seal similar to seal  139 . Alternatively, it may prove economical to apply a coating of material over the chip-coil-and-flex circuit accessory identification assembly of  FIG. 10 . Then, this assembly is held in place by seal  208 . 
         [0103]    In some versions of the invention, it may be possible to provide the accessory identification assembly with a C-shaped member that encases the RFID chip and complementary coil. In these versions of the invention, the coil would not extend completely circumferentially around the outer hub. In these versions of the invention, the C-shaped member would have an outer diameter that is greater than that of the adjacent inner wall of the outer hub. Then, upon the insertion of the accessory identification assembly into the outer hub bore, the C-shaped member would compression secure itself against the inner wall of the outer hub. In these versions of the invention, in order to ensure that the C-shape member is held in place, the outer hub may be formed with an annular groove in which the C-shaped member is seated. 
         [0104]    Also, alternative constructions of the coupling assembly may be possible. For example, in some versions of the invention, the wave spring and release button may be on opposite sides of the locking ring. In these versions of the invention, the lip portion of the locking ring, the portion that blocks movement of the outer hub  38  is located adjacent the wave spring. The spring biases the locking ring so that the lip is normally in the locked state. The release button is depressed to retract the lip into an adjacent slot in the collet so as to place the locking ring in the release state. 
         [0105]    Similarly, the biasing member that holds the locking ring in the locked state may have different forms than what has been described. For example, not all spring versions of this biasing member need be wave springs. In some versions of the invention, a coil spring or leaf spring may perform this function. Also, this biasing member need not always be a metal or plastic spring. In alternative versions of the invention, elastomeric material disposed between a static component integral with the handpiece housing and the locking ring may serve as the member that releasably holds the locking ring in the locked state. 
         [0106]    It should likewise be understood that the geometry of the components of this invention may vary from what has been described. For example, there is no requirement that the accessory outer hub and complementary handpiece opening in which the hub is inserted always have a circular profile. In other versions of the invention, it may be desirable that these components have an oval profile or in the form of a polygon, for example, a square or pentagonal shape. Similarly, the ears of the outer hub, which function as its lock tabs, may have a geometry different from what has been described. For example, there may be a reason to provide the longitudinally extending surfaces of these components with linear profiles. Clearly, other hubs of the cutting accessory of this invention may have other geometric features to facilitate the locking of the hub to the complementary handpiece. 
         [0107]    Also, it should be recognized that not all versions of this invention incorporate a motor as the power generating unit. In some versions of the invention, the power generating unit may consist of a device that generates ultrasonic energy, RF energy, thermal energy or photonic, light, energy. In these versions of the invention, the coupling member that transfers the power generated by the power generating unit to the cutting accessory will be different from what has been described. The coupling member may also be different if the power generating unit is the previously described motor  28 . For example, sometimes the motor output shaft  30  may not be provided with a drive pin. In these versions of the invention, teeth integral with the output shaft function as the coupling member and engage with complementary teeth on the accessory drive hub to transfer the motive power from the motor to the cutting accessory. 
         [0108]    Therefore, it is an object of the appended claims to cover all such variations and modifications as come within the true spirit and scope of this invention.