Abstract:
A surgical tool arrangement for performing endoscopic surgical procedures which includes a powered handpiece and a surgical cutting accessory which detachably connects to the handpiece. The cutting accessory incorporates a cutting head for resecting tissue and a suction arrangement at the distal end of the cutting accessory closely adjacent the cutting head which suction arrangement serves to evacuate tissue from the surgical site and additionally serves as a cleaning mechanism for the surgical cutting accessory. The accessory additionally incorporates a bearing arrangement for supporting the cutting element as same rotates within the housing element.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This claims the benefit of U.S. Provisional Application Ser. No. 62/064,719, filed Oct. 16, 2014. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention generally relates to a surgical tool arrangement useful for performing endoscopic surgical procedures which includes a powered handpiece and, more particularly, to a surgical cutting accessory which detachably connects to the handpiece and includes an outer housing element and an inner cutting element with a cutting head for resecting tissue and a suction arrangement at the distal end of the cutting accessory closely adjacent the cutting head which suction arrangement evacuates surgical debris from the surgical site and also operates as a cleaning mechanism for the cutting accessory to prevent buildup of surgical debris adjacent the cutting head. The accessory additionally incorporates a bearing arrangement for supporting the cutting element as same rotates within the housing element. 
       BACKGROUND OF THE INVENTION 
       [0003]    Endoscopic surgical procedures are routinely performed in order to accomplish various surgical tasks. In such a surgical procedure, small incisions or 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 other 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 desired 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 the 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 the 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 such procedures. Once such tool is sold by the assignee hereof under the trademark FORMULA®. This tool is in the form of a cylindrical handpiece designed to be held in the hand of the surgeon. The handpiece has a front or distal end provided with a coupling assembly for releasably holding a cutting accessory, and a motor disposed within a handpiece housing which drives the accessory. The cutting accessories, such as shavers, drills and burs, include an outer housing element having a hub appropriately configured to cooperate with the coupling assembly of the handpiece to lock the accessory thereto and an elongated housing tube having a proximal end fixed to the hub, and an inner cutting element having a drive shaft disposed within the housing tube. When the accessory is attached to the handpiece, the handpiece motor couples to the drive shaft of the accessory and moves same relative to the housing tube. The handpiece motor is selectively actuable to drive the accessory drive shaft so as to cause a desired cutting action at the distal end of the accessory. The handpiece is associated with a control unit which controls the functioning thereof, and is actuated by the user via appropriate buttons provided on the handpiece itself, at the control unit or through use of a footswitch. 
         [0005]    In an endoscopic surgical procedure, irrigating fluid is introduced into the surgical site. This fluid serves as a transport media for removing tissue and debris from the surgical site. In order to remove the irrigating fluid and the material contained therein, the above handpiece and the various accessories which are usable therewith together define a suction conduit. 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 accessory and the handpiece, the handpiece is typically provided with a manually operated valve which is manipulated by the surgeon to control suction of material away from the surgical site. 
         [0006]    Mechanical cutting accessories, such as the shaver, drill and bur discussed above, are commonly used in arthroscopic procedures, and allow for the resection of hard and soft bodily tissues, for example, those found within the knee, shoulder and other joints. A bur-type cutting accessory is sometimes used to resect bone or other hard tissues, and includes a cutting head with cutting features which when rotated serve to cut away targeted bone or hard tissue. Such cutting features may include straight or helically-oriented cutting edges which extend longitudinally along the cutting head of the bur. Another bur-type cutting accessory is a diamond bur which includes diamond particles as cutting features which are embedded in a metal surface of the cutting head. Such bur-type cutting accessories often have solid cutting heads so as to have sufficient strength for abrading or cutting hard tissue. A bur-type cutting accessory includes a cutting head with cutting features such as those described above which are exposed through a window formed at the distal end of the outer housing element when the cutting element is located therein. In some bur-type cutting accessories, the window formed in the outer housing element opens primarily sidewardly, so that the distal end of the outer housing element covers a portion or one side of the cutting features of the cutting head of the bur to allow the user to better target bone or hard tissue, and this type of configuration is sometimes referred to as a “hooded” bur. Alternatively, the entire geometry of the cutting head which defines the cutting features may project distally beyond the terminal end of the outer housing element, and this type of arrangement is often called “unhooded”. In a bur-type cutting accessory, as contrasted with a surgical shaver, the distal end of the outer housing element typically does not perform any tissue-cutting function, and serves essentially only to house and support the drive shaft of the inner cutting element and to shroud part of the cutting head thereof (in the case of a hooded arrangement), and the cutting of hard tissue is carried out by the cutting features of the cutting head. In an unhooded bur configuration, the outer housing element serves essentially only to house and support the drive shaft. As discussed above, bur-type cutting accessories are typically used for removal of particular bone or hard tissue types, and a variety of different bur geometries are available to specifically address the type of cutting the accessory is to carry out. 
         [0007]    Further, in one conventional bur-type cutting accessory, the cutting element includes an elongate and hollow tubular drive shaft and a cutting head with cutting features is provided as a solid member which is fixedly mounted to the distal end of the drive shaft. In order to draw suction through the cutting element in this type of accessory, a suction opening is provided at the distal end of the drive shaft. The suction opening opens sidewardly outwardly and communicates with the hollow interior of the drive shaft, and is located proximally of the cutting features of the cutting head. In operation, bone or other hard tissue removed or cut away by the cutting head is suctioned into the hollow interior of the drive shaft through the window of the outer housing element and the suction opening. In this type of cutting accessory, it is possible that soft tissue can become wrapped around the cutting head in an area just proximal to the cutting features, which can block suction through the suction opening, prevent evacuation of surgical debris, and result in the surgeon&#39;s field of view becoming occluded. Such an occurrence will typically require that the surgeon disassemble the cutting accessory and manually unclog the suction opening of the accessory before continuing with the surgery. 
         [0008]    Additionally, the various types of surgical cutting accessories as discussed above typically require some type of bearing arrangement which supports the inner cutting element as same rotates within the outer housing element. Such bearing arrangements may include one or more bushings or bearing sleeves provided on the inner cutting element which serve to radially support the inner cutting element within the outer housing element, and a thrust washer or spacer provided at the interface between the mating proximal portions of the inner cutting element and outer housing element which serves to axially support the inner cutting element relative to the outer housing element. In some devices, the bearing sleeve which provides radial support is a heat-shrunk plastic sleeve applied to the exterior of the drive shaft of the inner cutting element. The bushings/bearing sleeves are typically provided as separate components of the accessory, which can complicate assembly/manufacturing. Further, heat-shrunk plastic sleeves have a wide tolerance range, which can make it difficult to maintain the desired gap between relatively movable components. 
         [0009]    In an effort to obviate or at least minimize the disadvantages of known surgical accessories, a suction arrangement is provided which can be utilized to both evacuate surgical debris from the surgical site and to provide a self-cleaning function for the cutting accessory. Further, a bearing arrangement provides both radial and axial support for the inner cutting element relative to the outer housing element. The bearing arrangement according to one embodiment is integrated into existing structures of the surgical cutting accessory, and thus provides a simpler and more cost-effective design. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a perspective view of the surgical tool arrangement, including a handpiece with a surgical accessory attached thereto; 
           [0011]      FIG. 2  is an enlarged, fragmentary, longitudinal and cross-sectional view of the handpiece of  FIG. 1  with the surgical accessory attached thereto; 
           [0012]      FIG. 3  is a perspective view of the inner cutting element of the surgical accessory; 
           [0013]      FIG. 4  is a perspective view of the outer housing element of the surgical accessory; 
           [0014]      FIG. 5  is an enlarged and fragmentary top view of the distal end of the inner cutting element; 
           [0015]      FIG. 6  is an enlarged and fragmentary view of the distal end of the inner cutting element rotated approximately 90 degrees from the position shown in  FIG. 5 ; 
           [0016]      FIG. 7  is an enlarged and fragmentary top view of the surgical accessory; 
           [0017]      FIG. 8  is an enlarged longitudinal cross-sectional view of the surgical accessory of  FIG. 7 , as seen generally along line VIII-VIII in  FIG. 7 ; 
           [0018]      FIG. 8A  is an enlarged and fragmentary cross-sectional view of the surgical accessory, as seen generally along line VIIIA-VIIIA in  FIG. 8 ; 
           [0019]      FIG. 8B  is an enlarged perspective view of the hub of the inner cutting element in isolation; 
           [0020]      FIG. 9  is an enlarged and fragmentary top view of the distal end of the surgical accessory; 
           [0021]      FIG. 10  is an enlarged cross-sectional view of the surgical accessory, as seen generally along line X-X in  FIG. 9 ; 
           [0022]      FIG. 11  is an enlarged cross-sectional view of the surgical accessory as seen generally along line XI-XI in  FIG. 9 ; 
           [0023]      FIG. 12  is an enlarged and fragmentary top view of the distal end of the inner cutting element of a second embodiment of the surgical accessory; 
           [0024]      FIG. 13  is an enlarged and fragmentary view of the distal end of the surgical accessory of the second embodiment with the inner cutting element rotated approximately 180 degrees from the position shown in  FIG. 12 ; 
           [0025]      FIG. 14  is an enlarged and fragmentary top view of the distal end of the inner cutting element of a third embodiment of the surgical accessory; 
           [0026]      FIG. 15  is an enlarged and fragmentary view of the distal end of the surgical accessory of the third embodiment with the inner cutting element rotated approximately 180 degrees from the position shown in  FIG. 14 ; 
           [0027]      FIG. 16  is an enlarged and fragmentary perspective view of the distal end of the inner cutting element of a fourth embodiment of the surgical accessory; 
           [0028]      FIG. 17  is an enlarged and fragmentary perspective view of the distal end of the inner cutting element of the surgical accessory of the fourth embodiment, with the inner cutting element rotated approximately 90 degrees from the position shown in  FIG. 16 ; 
           [0029]      FIG. 18  is an enlarged and fragmentary top view of the distal end of the surgical accessory of the fourth embodiment; 
           [0030]      FIG. 19  is an enlarged and fragmentary top view of the distal end of the inner cutting element of a fifth embodiment of the surgical accessory; 
           [0031]      FIG. 20  is an enlarged and fragmentary view of the distal end of the inner cutting element of the fifth embodiment of the surgical accessory, with the inner cutting element rotated approximately 90 degrees from the position shown in  FIG. 19 ; 
           [0032]      FIG. 21  is an enlarged and fragmentary view of the distal end of the surgical accessory of the fifth embodiment. 
           [0033]      FIG. 22  is an enlarged and fragmentary longitudinal cross-section of a sixth embodiment of the surgical accessory; and 
           [0034]      FIG. 23  is an enlarged perspective view of the hub, in isolation, of the inner cutting element of the sixth embodiment. 
       
    
    
       [0035]    Certain terminology will be used in the following description for convenience in reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement and designated parts thereof. The words “forwardly” and “distally” will refer to the direction toward the end of the arrangement which is closest to the patient or which is first inserted into the patient, and the words “rearwardly” and “proximally” will refer to the direction toward the end of the arrangement which is furthest from the patient. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import. 
       DETAILED DESCRIPTION 
       [0036]    Referring to  FIGS. 1 and 2 , a surgical tool arrangement  10  is illustrated. The arrangement  10  includes a handpiece  11 , which at its distal end mounts thereon a surgical accessory  12 . 
         [0037]    The handpiece  11  is a commercially available surgical handpiece manufactured by the assignee hereof, under Model Nos. 375-704-500 and 375-701-500, and is accordingly only briefly described herein. The handpiece  11  includes an elongate outer housing  13  defining an elongate bore  14  therein. A motor  15  (shown diagrammatically only in  FIG. 1 ) is disposed within the housing bore  14 . The motor  15  includes an output or drive shaft  16 , which drive shaft  16  mounts a drive pin  17  at the distal end thereof. A power cable  18  is coupled to the proximal end of the handpiece  11  for supplying power to the motor  15 . 
         [0038]    The handpiece housing  13  defines therein an elongate suction bore (not shown) extending generally parallel to and sidewardly of the housing bore  14 . This suction bore communicates with a diagonally extending suction passage  20  defined in the housing  13 , which passage  20  provides communication between the distal end of the housing bore  14  and the suction bore. Suction is drawn through the handpiece  11  by a suction pump (not shown), which is connected to the handpiece  11  via a suction tube  21 . Suction flow through the handpiece  11  is regulated by an adjustable valve  22  having a valve stem (not shown) which is movably mounted in a valve bore  23  defined in the housing  13 . The valve  22  is adjusted by the user via a movable handle or arm  24  connected to the valve stem. The above handpiece suction arrangement is described in detail in U.S. Pat. No. 7,682,333 issued on Mar. 23, 2010, which patent is owned by the same assignee hereof and is hereby incorporated by reference herein in its entirety. 
         [0039]    The accessory  12  is removably attached to the distal end of the handpiece  11  by a coupling assembly  25  provided on the handpiece  11 . The coupling assembly  25  includes a generally ring-shaped collet  26  secured to the distal end of the handpiece housing  13 . A locking ring  27  is movably disposed in the collet  26  and is biased to hold the accessory  12  within the housing bore  14  of the handpiece  11 . A release button  28  is provided on the locking ring  27 , and is used to release the locking ring  27  and allow removal of the accessory  12  from the handpiece  11 . Further, a coil  30  is provided in the collet  26 , which is used to facilitate inductive signal transfer to/from a radio-frequency identification device (RFID) disposed in the accessory  12  as discussed below. 
         [0040]    Referring to  FIGS. 3, 4 and 7-8B , the accessory  12  will now be described. The accessory  12  defines a central longitudinal axis  31 , and includes an outer cannula or tubular housing element  32  and an inner tubular cutting element  33  disposed within the housing element  32 . The housing element  32  includes a hub  34  which defines the proximal end thereof. The hub  34  is defined by a generally tubular base body  35 , which defines therein a plurality of generally rectangular openings  36  adjacent the proximal end thereof which are distributed along the circumference of the hub  34  (only two of which are shown in  FIGS. 4 and 7 ). The base body  35  also has formed thereon a pair of outwardly-projecting, diametrically opposed and generally ramp-shaped ears  37  disposed distally of the openings  36 . The ears  37  cooperate with the coupling assembly  25  of the handpiece  11  to secure the accessory  12  therein. The hub  34  has a distal end defined by a head or nose  39  of a reduced diameter as compared to the base body  35 . Further, the hub  34  defines therein a bore  41  which opens through a distal end of the hub  34 . The bore  41  opens proximally into a counterbore  42  which opens proximally through a terminal end of the base body  35 . The bore  41  and counterbore  42  are joined to one another by a shoulder  43  which faces in the proximal direction and extends transversely between the bores  41  and  42 . The openings  36  of the base body  35  communicate with bore  42 . 
         [0041]    An annular seal  45  is disposed within the proximal end of the bore  42  of the hub  34 . With reference to  FIGS. 2 and 8 , the seal  45  is constructed of a resilient elastomeric material, and is defined by a main section  46  and axially-spaced proximal and distal sections  47  and  48  disposed at respective opposite ends of the main section  46 . The proximal section  47  defines thereon a pair of annular ribs  55  and  56 , which are disposed in sealing engagement with an inner annular surface of the collet  26  of the handpiece  11  when the accessory  12  is coupled thereto, as shown in  FIG. 2 . The distal section  48  defines thereon a plurality of outwardly projecting and diametrically-opposed lock tabs  57  which engage within the respective openings  36  of the hub  34  to secure the seal  45  to the hub  34  and fix the axial position of the seal  45  relative thereto. The distal section  48  additionally defines thereon a plurality of inwardly projecting and diametrically-opposed stop tabs  58 , which are generally radially aligned with the respective lock tabs  57 . As shown in  FIGS. 2, 8 and 8A , an RFID device  59  encapsulated within a ring structure is located within the hub bore  42  adjacent the distal section  48  of the seal  45 . 
         [0042]    The above-described coupling arrangement of the handpiece  11  and the arrangement of the encapsulated RFID device  59  and the coil  30  are disclosed in U.S. Pat. No. 7,887,559 issued on Feb. 15, 2011, which patent is owned by the same assignee hereof and is hereby incorporated by reference herein in its entirety. 
         [0043]    The outer housing element  32  additionally includes an elongate housing tube  64  which projects distally from the hub  34  (see  FIGS. 2, 4 and 7-8A ). The housing tube  64  has a proximal end  60  which is fixedly mounted within the bore  41  of the hub  34 . The proximal end  60  of the housing tube  64  in the illustrated embodiment is induction bonded to the hub  34  within the bore  41 , which hub  34  has a large induction core through which the proximal end  60  extends via bore  41 . In this regard, the proximal end  60  of the housing tube  64  may be knurled and/or chamfered so as to facilitate induction bonding of the proximal end  60  to the hub  34 . The proximal end  60  extends in the proximal direction axially beyond the shoulder  43  of the hub  34  so as to have an exposed free end  61  which extends into the hub bore  42 . The housing tube  64  defines an elongate bore or conduit  65  therein, in which the cutting element  33  is disposed as discussed below. The housing tube  64  has a distal end  66  which in the illustrated embodiment is cut so as to define a window  67  having an annular edge  68 , which window  67  in the illustrated embodiment is made via an angled cut, resulting in a window  67  which opens both sidewardly and distally of the tube  64 . Alternatively, the distal end  66  of housing tube  64  may be cut in a manner such that the annular edge  68  is oriented perpendicular to the axis  31 . Other configurations of the distal end  66  of the housing tube  64  may be provided, and the above are given only by way of example. 
         [0044]    Turning now to the cutting element  33  ( FIGS. 3 and 7-8B ), same includes a hub  80  which defines the proximal end thereof. The hub  80  incorporates a motor-engaging drive element  81  defining a proximally opening bore  82  and slots  84 , diametrically aligned pairs of which together define slots which extend transversely to the longitudinal axis  31  of the accessory  12 . The hub  80  additionally includes a neck  85  which projects distally from the drive element  81 . The neck  85  is joined to an enlarged head  86  by an intermediate section  62 . The head  86  defines the terminal distal part of the hub  80 . The outer diameter of the head  86  is slightly larger than the inward projection of the respective stop tabs  58  of the seal  45 . A proximally oriented bore  87  opens through the proximal end of the hub  80  and extends axially through the neck  85  and a portion of the intermediate section  62 , in which is fixed an elongate drive shaft assembly including a drive shaft  88 . The drive shaft  88  defines therein a suction passage  89  which is in communication with a pair of suction ports  90  defined in neck  85 , which suction ports  90  are in turn in communication with the suction passage  20  of the handpiece  11 . In the illustrated embodiment, the suction ports  90  open sidewardly from the hub  80 . The proximally-oriented bore  87  opens distally into a counterbore  63  formed in the hub  80  which opens distally through the head  86  thereof. The bore  87  and counterbore  63  are joined to one another by a shoulder  71  which faces in the distal direction and extends transversely to the axis  31  between the bore  87  and the counterbore  63 . In the illustrated embodiment, and with reference to  FIGS. 8 and 8B , a pair of channels  72  are provided diametrically opposite one another within the counterbore  63  and extend therealong. The channels  72  open radially inwardly and extend longitudinally from the shoulder  71  in the distal direction and open distally through the head  86  of the hub  80 . Further, each channel  72  opens radially outwardly via an opening  73  which extends completely through the wall of the intermediate section  62  of the hub  80 . 
         [0045]    With reference to  FIGS. 3, 5, 6 and 8 , the drive shaft assembly includes a cutting head  104 . In the illustrated embodiment, the drive shaft  88  and the cutting head  104  of the drive shaft assembly are constructed as separate components which are fixed to one another. In this regard, the drive shaft  88  may be constructed of a rigid plastic and a distal end  91  thereof induction welded to the cutting head  104 , which may be constructed of rigid metal, such as stainless steel. Alternatively, the drive shaft  88  and the cutting head  104  may be constructed as an integral or one-piece member formed from rigid metal, such as stainless steel. The cutting head  104  is generally cylindrical and partially tubular in the illustrated embodiment as discussed below. 
         [0046]    As best shown in  FIGS. 5, 6 and 10 , the cutting head  104  includes a tubular proximal end  106  of a generally constant diameter and which in the illustrated embodiment is fixed to the distal end  91  of the drive shaft  88 , a tubular neck portion  107  extending distally from the proximal end  106  and a distal end  109  which extends distally from a conical distal end  108  of the neck portion  107 . The majority of the neck portion  107  has an enlarged outer diameter as compared to the outer diameter of the proximal end  106 . Where the neck portion  107  adjoins the proximal end  106 , the neck portion  107  tapers gradually outwardly away from the axis  31  of the surgical accessory  12  as the neck portion  107  projects away from the proximal end  106 . The proximal end  106  and the neck portion  107  are each defined by respective walls  110  and  111 , the inner surfaces of which walls  110 ,  111  together define a suction passage  112  which extends proximally from the distal end  109  of the cutting head  104  and opens through the proximal end  106  for communication with the suction passage  89  of the drive shaft  88 . 
         [0047]    The distal end  109  of the cutting head  104  is configured for cutting bodily tissue and has a configuration of what is commonly considered a bur. The distal end  109  is generally cylindrical and defines an exterior surface  113  having formed thereon a plurality of cutting features, such as cutting edges  114 . In the illustrated embodiment, and as shown in  FIGS. 8 and 10 , the distal end  109  is a solid member. The cutting edges  114  project outwardly from the exterior surface  113  in a direction away from the axis  31 , and in the illustrated embodiment additionally extend in a helical manner about the axis  31  along the longitudinal extent of the distal end  109  and in a generally parallel manner with one another along a majority of the longitudinal extent of the distal end  109 . The cutting edges  114  extend gradually towards one another in the proximal to distal direction and terminate adjacent a tip  117  of the distal end  109 . A flute or groove  118  is defined between each adjacent pair of cutting edges  114 , which grooves  118  extend helically about the axis  31  along the distal end  109 . It will be appreciated that the cutting edges  114  may alternatively be non-helical or substantially straight so as to extend generally parallel with the axis  31  or so as to be oriented at an angle relative to the axis  31 . The respective grooves/flutes  118  in this embodiment would thus also be substantially straight. Further, the number of cutting edges  114  will vary depending upon the dimensions of the cutting head  104  and/or the type of cutting action desired, and the configuration of the cutting edges  114  as disclosed herein is presented only as an example of one suitable configuration for cutting edges of a cutting head  104 . 
         [0048]    Referring to  FIGS. 9 and 10 , the wall  111  of the tubular neck portion  107  has an outer surface  120  with an outer diameter which is greater than an outer diameter of the distal end or bur  109  and slightly smaller than the inner diameter of the housing tube  64 . Further, the configuration or contour of the outer surface  120  is similar to or substantially conforms to the contour of an inner surface  121  of the housing tube  64 . The outer surface  120  thus serves as a bearing surface via its engagement with the inner surface  121  of the housing tube  64 . The cooperation between the inner surface  121  and the outer surface  120  forms a distal bearing for rotatably supporting the drive shaft  88  within the housing tube at the distal end of the surgical accessory  12 . 
         [0049]    The wall  111  of the tubular neck portion  107  defines a suction opening therein which opens outwardly through the bearing surface  120 , and in the illustrated embodiment, a plurality of such suction openings  122  and  123  are provided within the wall  111  which open outwardly through the bearing surface  120 . The suction openings  122  and  123  are oriented in circumferentially spaced-apart relation with one another about the neck portion  107 . In the illustrated embodiment, the suction openings  122  and  123  are spaced at approximately 90 degree intervals from one another along the circumference of the neck portion  107 , and two of the suction openings  122  are located diametrically opposite one another (approximately 180 degrees from one another), are axially aligned with one another, and are located closer to the distal end or bur  109  than the remaining two suction openings  123 . The remaining two suction openings  123 , or proximal suction openings  123 , are axially aligned with one another and are diametrically opposite one another on the neck portion  107 . Each of the suction openings  122  and  123  extends completely through the wall  111  for communication with the suction passage  112  of the cutting head  104  and the suction passage  89  of the drive shaft  88 , and in the illustrated embodiment each suction opening  122 ,  123  has a circular configuration. 
         [0050]    As best shown in  FIGS. 10 and 11 , the placement of the suction openings  122  and  123  in the bearing surface  120  positions the openings  122  and  123  in close, face-to-face or opposed relationship (in a radial direction relative to the axis  31 ) with the inner surface  121  of the housing tube  64 . Further, each of the suction openings  122  and  123  has a pair of opposed edges  132  and  130  (see  FIGS. 5, 6 and 11 ) adjacent the bearing surface  120  of the neck portion  107  which edges, when the inner cutting element  33  is rotated inside the outer housing element  32 , are positioned in circumferentially opposed relation with the adjacent edge  68  of the housing element window  67  as discussed further below. These edges  130  and  132  can be provided with a blunt or non-acute configuration, a chamfered edge configuration suitable for non-aggressive cutting or resection of tissue such as the edge configuration shown in  FIG. 11 , or a sharp or acute edge configuration suitable for more aggressive cutting of tissue. 
         [0051]    The inner cutting element  33  is assembled to the outer tubular housing element  32  by inserting the distal end  109  of the cutting element  33  into the proximal end of the bore  42  of the hub  34 . During this insertion, the enlarged head  86  of the hub  80  expands the seal  45  and the head  86  pushes past the stop tabs  58 , at which point the seal  45  essentially resumes its original shape. The stop tabs  58 , while allowing some axial displacement of the cutting element  33  relative to housing element  32 , prevent the cutting element  33  from detaching or falling out of the housing element  32  due to gravitational forces. When the cutting element  33  is fully inserted into the housing element  32 , the free end  61  of the housing tube  64  extends in the proximal direction into the counterbore  63  of the hub  80  and abuts against the shoulder  71 , as best shown in  FIG. 8A . The wall of the hub  80  which defines the counterbore  63  has an inner surface  74  with a diameter which is similar to, but slightly larger than, the outer diameter of the free end  61  of the housing tube  64 , such that there is only a small radial clearance between the free end  61  and the inner surface  74 . The engagement of the outer surface of the free end  61  of the housing tube  64  with the inner surface  74 , and the abutting engagement of the free end  61  of the housing tube  64  with the shoulder  71 , provides a radial bearing and an axial bearing, respectively, at the proximal end of the surgical accessory  12 . As discussed further below, when the accessory  12  is mounted to the handpiece  11 , a spring  75  provided within the drive element  81  of the cutting element  33  cooperates with the handpiece  11  and biases the cutting element  33  axially in the distal direction relative to the outer housing element  32 , which serves to maintain the free or terminal end  61  of the housing tube  64  axially against the shoulder  71 . 
         [0052]    The mating areas between the inner surface  74  of the hub  80  and the outer surface of the free end  61  of the housing tube  64  can be provided with lubricant in order to minimize friction between these components during movement of the inner cutting element  33  relative to the outer housing element  32 . In this regard, and as best shown in  FIGS. 8 and 8B , lubricant can be applied to the counterbore  63  through the openings  73  and/or through the distally opening areas of the channels  72 , so that the lubricant will enter the channels  72  and lubricate between the free end  61  of the housing tube  64  and the hub  80 . 
         [0053]    The assembled accessory  12  is secured to the handpiece  11  in a similar manner to that described in the &#39;559 patent referenced above, and this assembly will accordingly be only briefly described here. The accessory  12  is attached to handpiece  11  by inserting the hubs  34  and  80  into the open distal end of the collet  26 . The ears  37  of the hub  34  seat within the collet  26 , and the locking ring  27  serves to hold the accessory  12  within the handpiece  11 . The above securement of the accessory  12  to the handpiece  11  causes the drive element  81  of the accessory  12  to engage the motor output shaft  16  of the handpiece  11 . More specifically, the drive pin  17  of the output shaft  16  seats within the aligned slots  84  of the drive element  81 , such that the rotational movement of the output shaft  16  is transferred to the cutting element  33 . Further, the drive pin  17  engages the spring  75  so as to axially bias the cutting element  33  in the distal direction. 
         [0054]    In operation, the distal end of the tool  10  is inserted into the surgical site. The cutting element  33  is controlled by a control unit (not shown) connected to the handpiece cable  18 , which control unit supplies electrical power to the motor  15  of the handpiece  11  in order to actuate the cutting element  33  and control the rotational speed thereof. If cutting of tissue is desired, then the motor  15  is activated so as to cause the cutting element  33  to rotate within and relative to the outer housing element  32 , which effectively rotates the cutting head  104  to allow the removal of tissue at the surgical site. In this regard, it will be appreciated that the control unit may include appropriate control buttons so as to allow the surgeon or operator to select the desired accessory operations. These control functions of the cutting element  33  may alternatively be performed directly from the handpiece  11  which would then include the appropriate control buttons thereon. Alternatively, the control unit may be associated with a switch, either through a suitable cable or wirelessly, to allow the surgeon to operate the controls remotely. Such a switch may be a footswitch or a hand switch. 
         [0055]    As shown in  FIGS. 9 and 10 , with the cutting element  33  disposed within the housing element  32  and the accessory  12  secured to handpiece  11  as described above, the cutting head  104  is positioned adjacent the window  67  of the housing element  32  so that at least a portion of the cutting head  104  is exposed. In this regard, the cutting features of the cutting head  104  are shown herein as being covered on one side thereof by the distal end  66  of the housing element  32 . However, it will be appreciated that other configurations of the housing element distal end  66  may be provided. For example, the housing tube  64  of the housing element  32  may be provided with a length which allows full exposure of the cutting features of the cutting head  104  axially beyond the distal end  66  of the housing tube  64 , so that the cutting features of the cutting head  104  are unhooded or uncovered completely. 
         [0056]    The annular edge  68  of the housing tube  64 , as shown in  FIG. 11 , is shaped so as to have a pair of opposed edges  70  which, when the cutting element  33  is assembled to the housing element  32  and is rotated relative thereto, act to clear surgical debris from the suction openings  122  and  123  as discussed further below. The edges  70  may be provided with a blunt or non-acute configuration, a chamfered configuration suitable for cutting or resecting tissue, or a sharp or acute configuration suitable for more aggressive tissue cutting. 
         [0057]    If desirable or necessary, suction can be provided at the surgical site by manipulating the valve  22  on the handpiece  11  to draw surgical debris from the surgical site, first through the window  67  of the housing element  32  and then through the suction openings  122  and  123 . In this regard, the axial location of the suction openings  122  and  123  along the neck portion  107 , the size of the window  67  of the housing element  32  and the distribution of the suction openings  122  and  123  about the neck portion  107  can be configured so that at least one of the suction openings  122  or  123  is located within the window  67  essentially at all times during rotation of the cutting element  33  relative to the housing element  32 . Surgical debris resulting from the cutting action of the cutting head  104  can be suctioned into the window  67  of the housing element  32  and into an exposed suction opening  122  and/or  123 , which debris is then suctioned into the suction passage  112  of the cutting head  104 , into the drive shaft suction passage  89 , into the handpiece suction passage  20  and proximally through the handpiece  11  towards the suction pump. The positioning of the suction openings  122  and  123  for communication with the window  67  and immediately proximate to the cutting features  114  of the cutting head  104  enables quick evacuation of the surgical debris from the surgical site. 
         [0058]    In conventional cutting accessories, it is common for soft tissue to become wrapped around the cutting features, or an area just proximal thereof, during a surgical procedure, which in turn can cause clogging of the suction opening located proximal to the cutting features as discussed above. However, because the suction openings  122  and  123  open outwardly through the bearing surface  120  and the bearing surface  120  is radially spaced from the inner surface  121  of the housing tube  64  by a relatively small amount, soft tissue is prevented from wrapping around the distal end  109  of the accessory  12  and clogging the suction openings  122  and  123 . Further, when the cutting element  33  is rotated within and relative to the housing element  32 , any tissue which is lodged or entangled within or adjacent the suction openings  122 ,  123  will be wiped away or dislodged by the edge  70  of the window  67  of the outer housing element  32  as the edge  132  or  130  of the suction opening  122  or  123  rotates towards or approaches the adjacent edge  70  of the housing window  67 . When the inner cutting element  33  is rotated within and relative to the outer housing element  32 , the suction opening  123  (or the suction opening  122 ) moves towards the stationary edge  70  of the window  67  of the outer housing tube  64 . When the suction opening  123  (or the suction opening  122 ) meets and moves past the edge  70 , a wiping or cleaning action will take place which, due to the close proximity (in the radial direction) of the edge  70  to the suction opening, will serve to clear any accumulated tissue from the suction opening. 
         [0059]    As discussed above, the edges  132  and  130  of the inner cutting element  33  and/or the edges  70  of the outer housing element  32  may be configured as cutting edges, which, in addition to the wiping action described above, provides a resection or cutting action at the suction openings  122  and  123 . Should tissue become lodged adjacent the window  67  during a procedure, according to this embodiment, the tissue will be resected between the respective edge  130 ,  132  of the suction opening  122  or  123  and the edge  70  of the window  67  of the outer housing element  32 , which edges together create a scissoring action when the cutting element  33  is rotated relative to and within the housing element  32 . More specifically, any tissue which is lodged within or adjacent the suction opening  122  or  123  will be caught by the edge  132  or  130  of the suction opening  122 ,  123  as same rotates towards the adjacent edge  70  of the housing window  67 , which effectively will server the tissue between the two edges ( 132  and  70 ,  130  and  70 ) and allow suction of the resected tissue away from the surgical site. 
         [0060]    The arrangement of the suction openings  122  and  123  on the bearing surface  120  of the cutting head  104  can thus prevent, or at least minimize, occlusion of the surgeon&#39;s field of view by surgical debris due to the wiping action performed by the edges  70  of the window  67  of the outer housing element  32  over the suction openings  122  and  123  as same rotate towards and past the adjacent edge  70  of the housing window  67 . Further, if the edges  130 ,  132  and/or  70  are configured as cutting edges, tissue resection can additionally be carried out. This arrangement will prevent the surgeon from having to dismantle the surgical accessory  12  from the handpiece  11  and remove the cutting element  33  from the housing element  32  in order to remove the tissue causing the clog. 
         [0061]    The window  67  of the outer housing tube  64  is sized, and the suction openings  122  and  123  are disposed in appropriate axial positions along the cutting head  104  of the drive shaft  88 , so that the suction openings  122 ,  123  are exposed (i.e. unblocked by the distal end  66  of the housing tube  64 ) through the housing window  67  along with at least a portion of the cutting head  104 . In this regard, the suction openings  122 ,  123  will be exposed to the surgical site through the window  67  when the suction openings  122 ,  123  are rotationally aligned with the window  67 , and in the illustrated embodiment at least two suction windows  122 ,  123  will be at least partially exposed at one time during rotation of the drive shaft  88 . This arrangement allows the evacuation of surgical debris through the window  67  directly into the suction openings  122 ,  123 . 
         [0062]    Further, the suction openings  122 ,  123  are provided as separate structures from the cutting head  104 . That is, the suction openings  122 ,  123  are not provided or defined in the cutting head  104 , for example, between the cutting edges  114  or otherwise directly on the cutting head  104 . This arrangement is easier to manufacture and also allows the cutting head  104  to have a structure, when necessary or desirable, which is sufficiently rigid to withstand aggressive cutting. While the suction openings  122 ,  123  are separate structures from the cutting head  104 , the suction openings  122 ,  123  are nonetheless positioned very close (in the axial direction) to the cutting head  104  which results in more immediate suctioning and thus removal of surgical debris. Additionally, the wiping action of the edges  70  of the outer housing element window  67  over the suction openings  122 ,  123  provides an efficient anti-clogging/cleaning mechanism. Also, in the embodiment wherein the suction opening edges  130  and  132  and/or the edges  70  of the housing element window  67  are configured as cutting edges, the scissoring action between the edges  130 ,  132  and the edges  70  allow for tissue resection adjacent the window  70 . Further, providing suction openings  122 ,  123  at varying axial locations along the bearing surface  120  allows suction, and in the embodiment where the edges  130 ,  132  and/or edges  70  are configured as cutting edges, a cutting action, over an increased area (in the axial direction) along the bearing surface  120 . In some conventional burr-type surgical accessories, the size of the suction openings or windows are necessarily made large in an attempt to prevent clogging thereof. These large-size suction openings or windows can cause the accessory to use a large amount of saline or irrigating fluid during surgery and thus can result in a high flow-rate. Since these accessories can extract more saline than the inflow pump can provide, the pressure at the surgical site (such as in a bodily joint) can fall and potentially cause joint collapse. For this reason, surgeons often keep the suction function of the accessory turned off and only occasionally turn same on to clear the field of view at the surgical site. The suction openings  122  and  123  can be made much smaller as compared to conventional accessories (in some cases 70% smaller than a conventional burr-type cutting accessory), due to the cooperation between the suction openings  122 ,  123  and the housing window  67  as discussed herein, which provides an efficient cleaning mechanism for the suction openings  122 ,  123 . The smaller size of the suction openings  122 ,  123  results in reduced saline consumption and accordingly reduces the possibility of joint collapse during surgery. Further, the surgeon is able to utilize and/or maintain suction through the accessory  12  during a cutting operation which will provide a better field of view of the surgical site during a cutting operation. 
         [0063]    The bearing arrangement described herein includes the distal bearing defined by the outer surface  120  of the inner cutting element  32  which engages with the inner surface  121  of the housing tube  64  of the outer housing element  32 , and the proximal bearing defined by the engagement of the outer surface of the free end  61  of the housing tube  64  with the inner surface  74  of the hub  80  and the engagement of the terminal end  61  of the housing tube  64  with the shoulder  71 . With respect to the proximal bearing, the increased depth (in the axial direction) at which the housing tube  64  is bonded to the hub  34  of the housing element  32 , resulting in the extension of the terminal end  61  of the housing tube  64  into the bore  42  and beyond the shoulder  43 , allows coupling or attachment of the hub  80  of the cutting element  33  to this terminal end  61 . This arrangement in effect allows the use of existing components, namely the housing tube  64  and the hub  80 , to provide a proximal bearing site, and the drive shaft  88 /cutting head  104  and the inner surface  121  of the housing tube  64  to provide a distal bearing site, and thus provides bearings for the inner cutting element  33  at axially opposite ends of a very stiff housing tube  64 . Due to the increased depth at which the housing tube  64  extends into the hub  34 , the stiff housing tube  64  and the handpiece  11  overlap at the connection point between the two, i.e. adjacent the collet  26 . This means that the tool  10  is stiff all of the way from the handpiece  11  to the distal end  109  of the accessory  12 , with very little stiffness lost at the connection between the handpiece  11  and the accessory  12  at the collet  26 , which provides a more rigid and stable tool  10 . Further, the utilization of the hub  80  of the cutting element  33  and the free end  61  of the housing tube  64  as both an axial and radial bearing lends stability to the accessory  12  at the proximal end thereof and ensures that a radial gap is maintained between the drive shaft  88  and the housing tube  64  at the proximal end of the accessory  12 . In some conventional arrangements, a metal or low-friction plastic spacer is used as an axial bearing between the rotating hub of the inner cutting element and the hub of the outer housing element. Thus, the utilization of existing components of the accessory  12  to provide both axial and radial bearing support provides a simpler and more cost efficient arrangement. 
         [0064]    In one embodiment, the wall  111  of the neck portion  107  of the cutting head  104  (which defines the outer surface  120 ) and the housing tube  64  may be constructed of stainless steel coated with a low-friction and wear resistant material. This construction reduces wear during surgery which in turn reduces particle generation at the surgical site, and provides hard, low-friction and corrosion-resistant surfaces. Some conventional surgical accessories utilize a metal-on-metal bearing arrangement at the distal end of the accessory wherein at least one of the bearing components is a separate component. Providing a bearing as a separate component is necessarily more difficult and expensive to manufacture. In contrast, the distal bearing arrangement is integrated into existing components, resulting in a less expensive and simpler arrangement. 
         [0065]    The cutting head  104 , in the illustrated embodiment, can be provided as an integral structure which is machined from a single stainless steel bar stock to form the cutting edges  114 , a larger diameter portion (the neck portion  107 ) proximal to the cutting edges  114  on which the outer (bearing) surface  120  is formed and the suction openings  122  and  123 . The drive shaft  89  can be constructed of plastic and induction bonded to the cutting head  104 . 
         [0066]    Utilizing a metal bearing surface, such as the surface  120  of the cutting head  104 , which is machined during formation of the cutting head  104 , provides a repeatable and very stable bearing surface in close proximity to the cutting features  114  of the cutting head  104 . This surface  120  can be machined to very tight tolerances such that the gap between the outer diameter of the bearing surface  120  and the inner diameter of the adjacent portion of the housing tube  64  can be kept very small and is easily repeatable during manufacture, meaning that the gap between the cutting edges  114  and the hood created by the distal end  66  of the housing tube  64  (when the bur is of a hooded-type as in the illustrated embodiment), is repeatable. As a result of this repeatability in gap size between components, as well as the stable bearing arrangement in close proximity (in the axial direction) to the cutting features  114  of the cutting head  104 , the accessory  12  is able to withstand significantly more force (sideload) before the cutting features  114  will collide or make contact with the distal end  66  of the housing tube  64 , which can potentially cause metal debris to be generated at the surgical site. The stable and low-friction bearing arrangement also means the accessory  12  is able to withstand significantly more force (sideload) before the drive shaft  88  makes contact with the housing tube  64 , which can potentially cause stalling out or failure of the accessory. 
         [0067]      FIGS. 12-21  illustrate additional embodiments of the surgical accessory  12  which are substantially identical to the first embodiment of the surgical accessory  33 , except that these embodiments incorporate alternative configurations or geometries of the suction openings provided in the bearing surface of the inner cutting element of the surgical accessory  12  as discussed below. 
         [0068]      FIGS. 12 and 13  illustrate a second embodiment of the surgical accessory. Components of the second embodiment which are similar or identical to components of the first embodiment of the surgical accessory  12  will include the same reference numbers as in the prior embodiment, plus “200”, and a detailed description of all components will accordingly not be provided. The surgical accessory  212  according to the second embodiment includes an inner cutting element  233  rotatably disposed within an outer housing element  232 . The inner cutting element  233  incorporates a drive shaft assembly including a drive shaft  288  having a distal end  291  with a cutting head  304 . The tubular neck portion  307  of the cutting head  304  defines therein a plurality, and here three, of suction openings  322  which open outwardly through the bearing surface  320  of the neck portion  307 . These suction openings  322  are substantially identical to one another and each has an elongated configuration and extends in a helical manner about the longitudinal axis  231  of the accessory  212  as the opening  322  projects longitudinally along the bearing surface  320 . In the illustrated embodiment, the suction openings  322  are uniformly circumferentially spaced from one another about the neck portion  307 . Each of the suction openings  322  extends completely through the wall  311  for communication with the suction passage  312  of the cutting head  304  and the suction passage  289  of the drive shaft  288 . Each of the suction openings  322  has a pair of opposed edges  332  disposed at the bearing surface  320 . 
         [0069]    The inner cutting element  233  is housed within the outer tubular housing element  232  and the assembled accessory  212  is secured to the handpiece  11  as in the prior embodiment. As shown in  FIG. 13 , with the cutting element  233  disposed within the outer housing element  232 , the cutting head  304  and the bearing surface  320  are positioned adjacent the window  267  of the housing element  232  so that at least a portion of the cutting head  304  and one or more of the suction windows  322  are exposed through the window  267 . Further, with the cutting element  233  assembled to the housing element  232 , during use, the edges  270  of the housing tube  264  act to wipe debris away from the suction openings  322  as the inner cutting element  233  rotates within the outer housing element  232 , as in the prior embodiment. The edges  332  of the suction windows  322  and/or the edges  270  of the housing tube  264  may be provided with edges suitable for cutting/resecting tissue. In this embodiment, the cutting edges  332  of the suction windows  322  cooperate with the edges  270  of the housing tube  264  to cut or resect tissue as the cutting element  233  rotates within the housing element  232  should this be necessary due to a buildup of surgical debris. 
         [0070]      FIGS. 14 and 15  illustrate a third embodiment of the surgical accessory. Components of the third embodiment which are similar or identical to components of the first embodiment of the surgical accessory  12  will include the same reference numbers as in the prior embodiment, plus “400”, and a detailed description of all components will therefore not be provided. The surgical accessory  412  according to the second embodiment includes an inner cutting element  433  rotatably disposed within an outer housing element  432 . The inner cutting element  433  incorporates a drive shaft assembly including a drive shaft  488  having a distal end  491  with a cutting head  504 . The tubular neck portion  507  of the cutting head  504  defines therein a plurality, and here eight, of suction openings  522  which open outwardly through the bearing surface  520  of the neck portion  507 . These suction openings  522  are substantially identical to one another and each is configured as a longitudinally elongated slot which extends in a substantially linear manner longitudinally along the bearing surface  520  substantially parallel to the axis  431  of the accessory  412 . In the illustrated embodiment, the suction openings  522  are uniformly circumferentially spaced from one another about the neck portion  507 . Each of the suction openings  522  extends completely through the wall  511  for communication with the suction passage  512  of the cutting head  504  and the suction passage  489  of the drive shaft  488 . Each of the suction openings  522  has a pair of opposed edges  532  disposed at the bearing surface  520 . 
         [0071]    The inner cutting element  433  is housed within the outer housing element  432  and the assembled accessory  412  is secured to the handpiece  11 . As shown in  FIG. 15 , with the cutting element  433  disposed within the outer housing element  432 , the cutting head  504  and the bearing surface  520  are positioned adjacent the window  467  of the housing element  432  so that at least a portion of the cutting head  504  and one or more of the suction openings  522  are exposed through the window  467 . Further, with the cutting element  433  assembled to the housing element  432 , the edges  470  of the housing tube  464  operate to wipe debris away from the suction openings  522 . If the edges  532  of the suction openings  522  and/or the edges  470  of the housing tube  464  are configured as cutting edges, then the cutting edges  532  cooperate with the cutting edges  470  of the housing tube  464  to cut tissue should this be necessary. 
         [0072]      FIGS. 16-18  illustrate a fourth embodiment of the surgical accessory. Components of the fourth embodiment which are similar or identical to components of the first embodiment of the surgical accessory  12  will include the same reference numbers as in the prior embodiment, plus “600”, and a detailed description of all components will not be provided. The surgical accessory  612  according to the fourth embodiment includes an inner cutting element  633  rotatably disposed within an outer housing element  632 . The inner cutting element  633  incorporates a drive shaft assembly including a drive shaft  688  having a distal end  691  with a cutting head  704 . The tubular neck portion  707  of the cutting head  704  defines therein a plurality, and here ten, of suction openings  722  which open outwardly through the bearing surface  720  of the neck portion  707 . These suction openings  722  are substantially identical to one another and each is configured as a slot which is elongated in a direction transverse to the axis  631 . Each suction opening  722  has an arc length or a circumferential extent which is less than 180 degrees, and the suction openings  722  are provided in diametrically opposed pairs in an axial direction along the bearing surface  720  with the openings  722  of each opposed pair of openings being separated from one another by a pair of diametrically opposed bridge sections  729  of the wall  711  of the neck portion  607 . In the illustrated embodiment, the bridge sections  729  of each pair of opposed suction openings  722  are circumferentially offset from the respective bridge sections  729  of the axially-adjacent pair or pairs of opposed suction openings  722  by approximately ninety degrees. Further, the opposed pairs of suction openings  722  are spaced axially from one another in a substantially uniform manner along the bearing surface  720 . Each of the suction openings  722  extends completely through the wall  711  of the neck portion  707  for communication with the suction passage  712  of the cutting head  704  and the suction passage  689  of the drive shaft  688 . Further, each of the suction openings  722  has a pair of opposed edges  732  disposed at the bearing surface  720 . 
         [0073]    The inner cutting element  633  is housed within the outer tubular housing element  632  and the assembled accessory  612  is secured to the handpiece  11 . As shown in  FIG. 18 , with the cutting element  633  disposed within the outer housing element  632 , the cutting head  704  and the bearing surface  720  are positioned adjacent the window  667  of the housing element  632  so that at least a portion of the cutting head  704  and one or more of the suction openings  722  are exposed through the window  667 . Further, with the cutting element  633  assembled to the housing element  632 , the edges  670  of the housing tube  664  wipe away debris from the suction openings  722  as in the prior embodiments. If the edges  732  of the suction openings  722  and/or the edges  670  of the housing tube  664  have cutting geometries, the cutting edges  732  of the suction openings  722  cooperate with the cutting edges  670  of the housing tube  664  to cut tissue adjacent the cutting head  704 . 
         [0074]      FIGS. 19-21  illustrate a fifth embodiment of the surgical accessory. Components of the fifth embodiment which are similar or identical to components of the first embodiment of the surgical accessory  12  will include the same reference numbers as in the prior embodiment, plus “800”, and a detailed description of all components will accordingly not be provided. The surgical accessory  812  according to the fifth embodiment includes an inner cutting element  833  rotatably disposed within an outer housing element  832 . The inner cutting element  833  incorporates a drive shaft assembly including a drive shaft  888  having a distal end  891  with a cutting head  904 . The tubular neck portion  907  of the cutting head  904  defines therein a plurality, and here four, of suction openings  922  and  923  disposed within the wall  911  which open outwardly through the bearing surface  920  of the neck portion  907 . The suction openings  922  and  923  are oriented in circumferentially spaced relation with one another about the neck portion  907 , and in the illustrated embodiment the suction openings  922  and  923  are spaced at approximately 90 degree intervals from one another along the circumference of the neck portion  907 . Two of the suction openings  922  are configured as longitudinally elongated holes and these suction openings  922  are diametrically opposed to one another (approximately 180 degrees from one another) and are axially aligned with one another, and the remaining two suction openings  923  are axially aligned with one another and are diametrically opposed one another on the neck portion  907 . The suction openings  923  in the illustrated embodiment are configured as circular holes. Each of the suction openings  922  and  923  extends completely through the wall  911  for communication with the suction passage  912  of the cutting head  904  and the suction passage  889  of the drive shaft  888 . Each suction opening  922  has a pair of opposed edges  932  disposed at the bearing surface  920 , and each suction opening  923  has a pair of opposed edges  930  disposed at the bearing surface  920 . In the illustrated embodiment, the suction openings  922 , due to their longitudinally elongated shape, extend over a greater axial distance than the suction openings  923 . 
         [0075]    The inner cutting element  833  is housed within the outer tubular housing element  832  and the assembled accessory  812  is secured to the handpiece  11 . As shown in  FIG. 21 , with the cutting element  833  disposed within the outer housing element  832 , the cutting head  904  and the bearing surface  920  are positioned adjacent the window  867  of the housing element  832  so that at least a portion of the cutting head  904  and one or more of the suction openings  922  and  923  are exposed through the window  867 . Further, with the cutting element  833  assembled to the housing element  832 , the edges  870  act to wipe away debris from the suction openings  922  and  932 . If the edges  932  and  930  and/or the edges  870  of the housing tube  864  are configured as cutting edges, then the cutting edges  932  and  930  of the suction openings  922  and  923  cooperate with the cutting edges  870  of the housing tube  864  to cut tissue should this be necessary due to a buildup of surgical debris adjacent the cutting head  904 . 
         [0076]      FIGS. 22 and 23  illustrate a sixth embodiment of the surgical accessory. Components of the sixth embodiment which are similar or identical to components of the first embodiment will include the same reference numbers as in the first embodiment, plus “1000”, and a detailed description of all components will accordingly not be provided. The surgical accessory  1012  according to the sixth embodiment incorporates an alternative configuration of the hub of the inner cutting element which accommodates a larger diameter housing tube of the outer housing element. In this regard, the hub  1080  of the inner cutting element  1033  of this embodiment includes a substantially cylindrical protrusion  150  which extends axially in the distal direction from the neck  1086  of the hub  1080  and has a smaller outer diameter than the outer diameter of the neck  1086 . The neck  1086  and the protrusion  150  are joined to one another by a shoulder  1071  which faces in the distal direction and extends transversely relative to the axis  1031  between the protrusion  150  and the neck  1086 . The hub bore  1087  in this embodiment has a substantially constant inner diameter and opens proximally through the drive element  1081  and distally through the protrusion  150 . As best shown in  FIG. 23 , the protrusion  150  has an outer surface  151  which defines therein a pair longitudinally extending chamfers or flats  152  which extend from the distal terminal end of the protrusion  150  to the head  1086 . Further, the head  1086  defines therein a pair of transversely extending channels  153  which extend radially outwardly from respective inner ends of the flats  152  and open radially through the head  1086 . 
         [0077]    The housing tube  1064  of the outer housing element  1032  in this embodiment, as in the first embodiment, has a proximal end  1060  which is induction bonded to the hub  1034 , which hub  1034  has a large induction core through which the proximal end  1060  extends via the bore  1041 . The proximal end  1060  extends in the proximal direction axially beyond the shoulder  1043  of the hub  1034  so as to have an exposed free end  1061  which extends over the outer surface  151  of the protrusion  150  of the hub  1080  of the inner cutting element  1033 . 
         [0078]    When the cutting element  1033  is fully inserted into housing element  1032 , the free end  1061  of the housing tube  1064  extends over the protrusion  150  like a sleeve, and the free terminal end  1061  of the housing tube  1064  abuts axially against the shoulder  1071 , as shown in  FIG. 22 . The outer diameter of the outer surface  151  of the protrusion  150  is slightly smaller than the inner diameter of the free end  1061  so as to allow the insertion of the protrusion  150  thereinto and such that there is only a small radial clearance between the inner surface of the free end  1061  and the outer surface  151 . The radial engagement of the outer surface  151  with the inner surface of the free end  1061  of the housing tube  1064  and the axial engagement of the free terminal end  1061  of the housing tube  1064  with the shoulder  1071  provides both a radial bearing and an axial bearing, respectively, at the proximal end of the surgical accessory  1012 . When the accessory  1012  is mounted to the handpiece  11 , a spring (not shown here, but similar to the spring  75 ) provided within the drive element  1081  of the cutting element  1033  cooperates with the handpiece  11  and biases the cutting element  1033  in the distal direction relative to the outer housing element  1032 , which serves to maintain the free or terminal end  1061  of the housing tube  1064  against the shoulder  1071 . The mating areas between the inner surface of the free end  1061  of the housing tube  1064  and the outer surface  151  of the protrusion  150  can be provided with lubricant in order to minimize friction between these components during movement of the inner cutting element  1033  relative to the outer housing element  1032 . In this regard, lubricant can be applied to the flats  152  and/or the channels  153  so as to lubricate the areas between the housing tube  1064  and the hub  1080 . 
         [0079]    Although particular preferred embodiments of the invention are disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.