Abstract:
A burr attachment removably attached to an adapter rotary driven by a motor that includes a tube with a wire shaft supported therein and a wire coil (no spring rate) serving as a journal bearing rotary supporting the wire shaft and having each of the coils randomly touch the outer periphery surface of the wire shaft and the inner peripheral surface of the tube to enhance cooling and attenuate vibrations while allowing the burr attachment to be bent without kinking. The burr attachment includes a proximal end support and a distal end support that removably attaches to the adapter. The wire shaft is affixed to the proximal end support and rotates relative to the distal end support operatively connected to the adapter. Only the burr attached is removable and disposable while the adapter and motor are re-usable.

Description:
RELATED APPLICATIONS 
     This invention relates to the patent application concurrently filed and entitled SURGICAL DRILL WITH CURVED BURR ATTACHMENT AND METHOD filed by the same inventors and assigned to the same assignee and incorporated in its entirety herein bearing Ser. No. 12/387,838 filed on May 8, 2009. 
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable 
     TECHNICAL FIELD 
     This invention relates to a surgical cutting instrument (Curved Burr Attachment) and particularly to a portable and disposable burr attachment capable of use with the Curved Burr Attachment. The burr attachment of this invention has the ability to utilize different sized ball cutters primarily used for cutting bone and being capable of changing the angle of the attachment to different angles to fit into minute curved portions of the anatomy, as for example, the middle ear, although this surgical drill can be utilized for other surgical procedures. 
     BACKGROUND OF THE INVENTION 
     This invention is particularly efficacious because it is disposable and bendable without kinking and is characterized as being easily fitted into and removable from the adapter of a Curved Burr Attachment and that it is cost effective. What is meant by disposable in the context of this patent application is that the attachment, namely, the burr and its supporting structure (burr attachment) are detachable from the drill motor and the adapter and can be discarded. In the prior art, for example, the burr and its extensions are made integral with the adapter (sometimes referred to as the clutch or clutching mechanism) so that in order to make the burr disposable, the adapter, being attached thereto, is, of necessity, also disposable. It is readily understood that this is a less desirable scenario because it is less cost effective. 
     A good example of the differences between a more cost effective disposable component and a less cost effective disposable component is a comparison with the present invention and the instruments disclosed in the US Publication No. 2005/0177168 invented by Brunett, et al and entitled HIGH SPEED SURGICAL CUTTING INSTRUMENT (which is incorporated in its entirety herein by reference). In the present invention the comparable medical instrument is comprised of a motor, an adapter and the Curved Burr Attachment which is essentially the same elements of the instrument disclosed in the Publication, although the terminology is different. The elements in the instrument disclosed in the Publication, supra, that compares to the Curved Burr Attachment is the wire and the cutter extending at the end of the wire and its support structure, the chuck mechanism and the motor. Since the wire/cutter and support mechanism also includes an integral chuck mechanism (comparable to the adapter of the present invention) that serves to connect to the motor, the disposable portion includes the wire/cutter and its support mechanism, as well as the clutch mechanism. In contrast, the present invention merely disposes the burr attachment of the Curved Burr Attachment instrument and hence, the remaining portion of the instrument, namely, the adapter (the more expensive portions of the tool), are re-usable. What the industry needs and desires is a tool, of this type, which is extremely small, (ball cutters range in 0.5 mm-2 mm) which includes a disposable burr that is substantially inexpensive and hence, cost effective. 
     In addition to the ability to bend the burr attachment at-will and the burr attachment being disposable in a cost effective manner, the particular manner in which lubrication is applied to the burr is unique. In the present invention the wire-shaft of the burr is surrounded by a coil wire that extends to approximately from the proximate end to the distal end of the wire-shaft and is oriented in such a manner that the helix formed by the coil wire is in a upward direction so that by placing grease at the distal end, the rotation of the wire-shaft causes the grease to migrate from the distal end to the proximate end, namely, in the upward direction. 
     In addition to the lubrication feature and the bending without the kinking feature of the present invention, the coil wire which is fixed and non-rotatable, also serves another function, i.e. it dissipates heat. This is accomplished by judiciously locating the coil wire between the inner wall of the support sleeve or tube of the burr attachment and the wire-shaft such that the outer and inner edges of each coil touches both the side of the inner wall of the support sleeve and the outer periphery of the wire-shaft, respectively. This serves to conduct the heat away from the wire-shaft and from internally of the support sleeve. Distributing the heat dissipation load in this manner reduces the heat or slows down the heat at the cutter resulting in additional time that the Curved Burr Attachment can be in continuous use in a medical procedure. As one in this technology knows the heat generated by the cutter can adversely affect nerves and other portions of the anatomy. Further this arrangement attenuates vibrations created by the rotation of the wire shaft. 
     Another function of the coil wire is that it permits the bending of the burr attachment without causing kinking. In accordance with this invention, the burr attachment t may be bent at the factory and, at the option of the surgeon; it may be bent at-will. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to provide an improved disposable burr attachment. 
     A feature of this invention is to provide a coil wire mounted in a support tube that surrounds the wire-shaft of the burr attachment such that it prevents kinking when the burr attachment is bent and it serves to provide heat transfer from the wire shaft to the inner diameter of the support tube surrounding the coil wire and provides a means for migrating grease from the distal end of the support tube upwardly toward the proximal end for lubricating the wire-shaft. This arrangement also attenuates vibrations created by the rotation of the coil wire. 
     Another feature of this invention is the inclusion of the proximal end support and the distal end support mounted on the end of the tube support that includes judicious dimensions that allow the attachment and the detachment of the burr attachment from the surgical instrument that provide means for rotating the wire shaft and locating the cutter in an exact and predetermined position. 
     Another feature of this invention is that it is designed to be disposable after a single use and is capable of use with a surgical drill that rotates at 80,000 revolutions per minute or higher. 
     The foregoing and other features of the present invention will become more apparent from the following description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view in elevation and phantom illustrating a Curved Burr Attachment including the burr attachment of this invention attached thereto and illustrating the various positions that the instrument can be bent into; 
         FIG. 2  is a side elevation view of the burr attachment of the present invention; 
         FIG. 2A  is a sectional view in elevation of the burr attachment depicted in  FIG. 2 . 
         FIG. 2B  is a fragmentary enlarged view of a portion of  FIG. 2A  depicting the relationship of the wire shaft, the tube support and the coil wire of the present invention; 
         FIG. 3  is a perspective view of the distal end support of the present invention; 
         FIG. 3A  is a side view in elevation illustrating the distal end support of the unit depicted in  FIG. 3 ; 
         FIG. 3B  is a sectional view of the distal end support depicted in  FIG. 3 ; 
         FIG. 3C  is an enlarged partial view of the distal end support including an annular groove formed on the peripheral surface of the smaller end portion formed in accordance with this invention; 
         FIG. 4  is a perspective view of the proximal end support of this invention; 
         FIG. 4A  is a sectional view of the proximal end support depicted in  FIG. 4 ; 
         FIG. 4B  is a side elevation view of the proximal end support depicted in  FIG. 4 ; 
         FIG. 4C  is an end view of the unit depicted in  FIG. 4 ; 
         FIG. 4D  is an enlarged partial view of the proximal end support illustrating An indent to be formed on the peripheral surface of the smaller end portion in accordance with this invention; 
         FIG. 5  is an enlarged view in elevation illustrating the coil wire of this invention; 
         FIG. 6  is a perspective view illustrating the tube support tube for the burr attachment; 
         FIG. 6A  is a sectional view of the support tube depicted in  FIG. 6 ; and 
         FIG. 7  is a view in elevation of the wire shaft and cutter of this invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It will be noted that in the description of the elements of this invention as shown in each of the FIGS. in this patent application may be out of proportion with respect to the overall picture of the inventive unit. As for example, some of the elements are shown in a small size and some of the elements are shown in an enlarged size. The purpose, obviously, is to more clearly define the invention and better describe the function of each of the elements. It is to be understood by those skilled in this art that the drawings are not manufacturing drawings, but are drawings used to illustrate the invention and to teach the concept and the workings thereof. Moreover, while the burr attachment of this invention is disclosed as being capable of use in a particular adapter, it is to be understood that other adapters can be used without departing from the scope of this invention and that this invention, amongst other things, teaches the concept of making the burr attachment, per se, disposable and bendable without incurring kinks. 
     As best seen in  FIGS. 1 and 2 , this invention is capable of use with a high speed (80,000 RPM-90,000 RPM) surgical instrument that is particularly efficacious for operating on small bones as for example, those found in the ear, nose and throat area, although not restricted thereto and generally illustrated as reference numeral  10  comprising a motor  12  (shown in phantom), an adapter  14  and the burr attachment  16  with the capability of being bent as shown in phantom and the burr attachment being disposable as will be described in detail herein below. While the particular motor used to rotate the drilling burr is of no moment, the X-Max® series or the E-Max® series, pneumatic and electric motors, respectively, are contemplated for use with this invention and are commercially available from the assignee of this invention, namely, The Anspach Effort, Inc of Palm Beach Gardens, Fla. 33410. 
     The adapter  14 , while not a part of this invention, is described in the aforementioned patent application bearing Ser. No. 12/387,838 and for further details reference should be made to this document. Suffice it to say that the adapter is removably coupled to the motor and the burr attachment is removably coupled to the adapter for imparting rotary motion to the cutter that is attached to the wire shaft of the burr attachment. 
     The invention is best described by referring to all of the Figs wherein the medical instrument sometimes referred to as the Curved Burr Attachment generally indicated by reference numeral  10  comprising the motor  12  (shown in phantom, the adapter  14  and the burr attachment  16 , which is the subject matter of this invention. The burr attachment  16  is removably coupled to the adapter  14  as described in the aforementioned application bearing Ser. No. 12/387,838 and comprises a tube support  18 , a wire shaft  20  and cutter  22 , a distal end support  24 , a proximal end support  26  (see  FIGS. 2 &amp; 3 ), coil wire  30 , and nose cap  28 . The cutter  22  may be a spherical ball with a diamond coating or with cut-in flutes. These devices are well known and for this particular medical instrument these cutters are particularly small, say from 0.5 mm to 2 mm. 
     All the elements of the burr attachment are made from a surgical steel or other suitable material where the hardness and tensile strength of the wire shaft  26  and attached cutter  22 , the tube  18 , proximal end support  26 , distal end support  24  and nose cap  28  are higher than the hardness and tensile strength of the coil wire  30 . (Unlike a spring, the coil wire  30  does not exhibit any spring-like characteristics and has no spring rate) These parameters are selected to assure that the burr attachment is sufficiently rigid to support the high rotational speed, yet the wire coil  30  is sufficiently malleable so that the burr attachment can be hand bent without incurring any kinking. 
     As alluded to in the above paragraphs, the burr attachment  16  is disposable. Hence, this invention assures that the burr attachment  16  is both easily inserted into and easily removed from the adapter. To this end the distal end support  24  and proximal end support  26  are judiciously dimensioned. As best seen in  FIGS. 3 ,  3 A  3 B,  4 A,  4 B and  4 C, the proximal end support  26  includes a generally cylindrical shaped main body  34 , an annular groove  36  disposed intermediate the ends thereof, a tip portion  38 , a flat portion  44  formed on the periphery of the main body  34  and adjacent to the tip portion  38 , large diameter recess  40  formed on one end remote from the tip portion  38  and a smaller diameter bore  42  extending axially from the large diameter recess  40 . Preferably the tip portion  38  is asymmetrically shaped so that the tip is formed in a shape of an ellipse as shown in  FIG. 4C . The larger diameter recess  40  serves to receive the proximal end of the distal end support  24  as will be described in more detail herein below. The smaller diameter bore  42  serves to receive the proximal end of the wire shaft  20  which is united to the proximal end support  26 , say, by swaging, shrink fitting or the like. In this particular embodiment, the holes  51  serve to receive a tool (not shown) used to swage the main body  34  to wire shaft  20  to form an integral unit so that the wire shaft  20  rotates with the proximal end support  26  for powering the cutter  22 . The annular groove  36  serves to cooperate with the adapter such that it couples the burr attachment so that the proximal end support  26  and wire shaft  20  are rotated. The pertinent dimensions of the proximal end support  26  are as follows in inches: 
     a=0.450; b=0.160; c=0.235; d=0.300; e=0.051; f=0.20; i=0.020 and the tip angle g=30° 
     The distal end support  24 , as best seen in  FIGS. 3 ,  3 A and  3 B, comprises generally cylindrical main body  56  including a larger diameter portion  58 , a smaller diameter portion  60 , a flat portion  62  formed on the periphery of the main body  56  intermediate the ends thereof a slot  64  formed on the periphery of the main body  56  adjacent to a flat portion  62  formed on the periphery of the main body  56 , a larger diameter recess  61 , a smaller diameter bore  63  and a grip portion  66  formed on the end of the main body  56  remote from the smaller diameter portion  60 . The slot  64  cooperates with the adapter such that it locates the cutter relative to the tip of the adapter and the distal end support is held fixed relative to the adapter. The grip portion  66  in this embodiment is formed by axially spaced annular ribs but other known configurations, like knurling, can be employed. The pertinent dimensions of the distal end support  24  are substantially as follows in inches:
         n =0.785; p =0.276; r =0.150; s =0.550; t =0.0725 and q =0.026       

     As noted in  FIG. 2  the peripheral end support  26  is fitted into the distal end support  24  such that the smaller diameter  60  fits into the slot  40  and the proximal end of the tube support  18  and coil wire  30  fits into the larger diameter recess  61 , which define a seat  65  therefore. The diameter of the bore  63  (0.026) is larger than the diameter of the of the wire shaft  20  (0.020) such that it is capable of freely rotate therein and since the wire shaft  20  is locked into the peripheral end support  26  it will rotate when the adapter rotates the peripheral end support  26 . The wire shaft  20  and cutter  22  are shown in  FIG. 7 . 
     As noted from  FIG. 2A  the coil wire  30  is mounted in. the seat  80  defined by the proximal end of the nose cap  28  and the seat  65  defined by the proximal end of the recess  61  and is held in place between these seats. When the coil wire  30  is installed into the tube  18  each end thereof bears against the spring seat  65  and the spring seat  80  formed when the nose cap  28  is inserted, such that the nose cap  28  will hold the coil wire  30  in place. This assures that coil wire  30 , surrounding the rotating wire shaft  20 , remains fixed. Hence, when the wire shaft is rotating, randomly, each of the coils of the coil wire will touch the inner surface of the tube  18  and outer periphery of the coil wire  30 . An enlarged view of the coil wire is shown in  FIG. 5  where the substantial value of h=2.240. A view of the tube support  18  is disclosed in  FIGS. 6 and 6A  where the substantial values of k=2.650 and m=0.042. 
     It will also be noted and in accordance with this invention that the helix orientation of the coils of coil wire  30  are in a direction as seen in  FIG. 2B  are from right to left or looking from the right hand end of  FIG. 2B  they are in a clockwise direction. The direction of the helix serves to flow grease in the upward direction toward the proximal end. Because of the orientation of the coils, grease inserted at the distal end of the burr attachment unit in a clearance between the wire shaft  20  and inner diameter of the nose cap  22  into the tube  18  so that when the wire shaft  20  rotates this motion forces the grease toward the proximal end of the burr attachment which lubricates the entire the wire shaft  20 . 
     It will also be noted and in accordance with this invention, as evidenced in  FIG. 2B , that the peripheral top and bottom surfaces  82  and  84  of each coil of coil wire  30  touch, by a point contact, the inner diameter surface  86  of tube support  18  and the outer surface  88  of wire shaft  20  and this connection serves to minimize the heat transfer through the coil wire  30  and tube  18 . This minimizing of the heat transfer of wire shaft  20  serves to keep the outer tube  18  cooler than it would otherwise be without this feature. The importance of maintaining the outer surface of tube  18  cooler by virtue of this heat transfer feature of this invention results in enhancing the operational time of the Curved Burr Attachment. In addition, because of the location of the coil wire  30 , namely, by the touching of the wire shaft  20  and of the inner surface of tube  18 , vibration generated by the rotating wire shaft  20  of the Curved Burr Attachment is attenuated. 
     It will be appreciated that in certain operations, particularly affecting the ear, the surgeon may have to re-adjust the angle of the burr attachment. Since the coil wire  30  is mounted between tube  28  and wire shaft  20 , the surgeon can bend the burr attachment to any desired angle to suit the particular operation being performed. Because of this design, the burr attachment  16  will not kink and will leave a smooth bend and yet the tube and wire shaft will provide sufficient rigidity to perform the rotation in a precise manner. 
     In some of the embodiments of this invention the diameter of cutter  22  is smaller than the diameter of the wire shaft  20  which could under certain circumstances cause a problem, as for example, in the insertion and removal of the burr attachment  16 . To solve this problem the distal end support  24  includes the annular groove  100  formed on the smaller diameter portion  60 . And a dimple or indent  102  is formed on the larger diameter portion  34  adjacent to the larger bore portion  40  of the proximal end support  26 , obviating the possibility of the cutter  22  and wire shaft  20  from inadvertently falling out. Obviously, the dimple or indent  102  is formed after the proximal end support  26  and the distal end support  24  are assembled in the assembled burr attachment  16 . 
     Although this invention has been shown and described with respect to detailed embodiments thereof, it will be appreciated and understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the disclosed invention.