Abstract:
A cutting burr that includes a pair of axially spaced diamond-shaped portions designed to be keyed into a spindle of a locking mechanism of a high speed surgical drilling instrument and adapted to fit into a single pawl thereof to lock said cutting burr in place so as to prevent axial movement thereof and provide concentric rotation of said cutting burr without any wobbling. The orientation of both portions may be identical with respect to a center plan and diamond shape in the portion at the proximal end of the shank of the cutting tool may be larger than the intermediately located diamond shape of the other portion. The apexes of the facets of the six-sided diamond shape may be disposed below the surface of the shank of the cutting burr.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The subject matter described in this application is related to subject matter disclosed in the following commonly assigned application: U.S. patent application Ser. No. ______ (Attorney Docket No. SYTH.01601US1 (T01601US1)), filed on even date, entitled “SURGICAL DRILL INSTRUMENT WITH MOTOR AND LOCKING MECHANISM TO RECEIVE AN ATTACHMENT AND A CUTTING BURR,” which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    When performing surgery, surgeons may utilize a surgical drilling instrument for drilling, cutting or shaping bones that utilize a numerous different kinds and sizes of cutting burrs and attachments. During certain medical operations, the cutting burr needs to be changed. The change must be done timely and efficiently in view of the surgical demands. To this end, the portion of the cutting burr, namely, the proximate end of the shank typically lacks a configuration to accommodate this change of the cutting burr. 
       SUMMARY 
       [0003]    Disclosed herein is a cutting burr that provides for a quick release that is fast and simple, and which facilitates the insertion of the cutting burr into a surgical drilling instrument. The cutting burr may have a pair of axially spaced six sided diamond-shaped portions, where one diamond-shaped portion may be formed at an edge of the proximal end of the cutting burr and provides a positive connection with a drive spindle that is connected to a drive motor of the surgical drilling instrument. A second, axially disposed diamond-shaped portion is adapted to mate with a locking pawl of the surgical drilling instrument. The locking pawl engages the axially disposed diamond-shaped portion to lock the cutting burr into the surgical drilling instrument with substantially no axial movement. 
         [0004]    In some implementations, a detent pawl is provided to hold the cutting burr within the surgical instrument when it is in a loading position. The detent pawl may engage the axially disposed diamond-shaped portion at a side opposite the locking pawl. 
         [0005]    In some implementations, the diamond-shaped portion at the proximal end is sized such that it can be used with older surgical drilling instruments that may not be provided with a complementary receiving recess for the diamond-shaped portion. 
         [0006]    This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The foregoing summary is better understood when read in conjunction with the appended drawings. For the purposes of illustration, there is shown in the drawings exemplary implementations; however, these implementations are not limited to the specific methods and instrumentalities disclosed. In the drawings: 
           [0008]      FIG. 1  a fragmentary top plan view illustrating the axially spaced six-sided diamond-shaped cut out portion or portions formed on the proximate end of the shank of the cutting burr; 
           [0009]      FIG. 2  is a perspective view of  FIG. 1 ; 
           [0010]      FIG. 3  is another prospective view of  FIG. 1  slightly turned illustrating one of the facets in each of the six-sided diamond-shaped portions; 
           [0011]      FIG. 4  is another perspective view of  FIG. 2  slightly turned illustrating the top facets of the six-sided diamond-shaped portions; 
           [0012]      FIG. 5  is an end view taken along lines  5 - 5  of  FIG. 3  illustrating the shape of the six-sided diamond-shaped portion formed in the cutting burr shank; 
           [0013]      FIG. 6  is a sectional view taken along lines  6 - 6  of  FIG. 4  illustrating the shape of the six-sided diamond-shaped portion and illustrating the different sizes and the orientation of the six-sided diamond portion formed in the cutting burr shank; 
           [0014]      FIGS. 7A and 7B  illustrate a backwards compatibility of the cutting burr of  FIGS. 1-6  within a receiving portion of conventional surgical drill; 
           [0015]      FIGS. 8A and 8B  illustrate a self-alignment aspect of the diamond-shaped portion at a proximal end of the cutting burr in relation to a keyed slot of a surgical drill; 
           [0016]      FIG. 9  is an elevated view of the cutting burr with a spherical shaped cutting bit illustrating the diamond-shaped portions formed in the shank thereof; 
           [0017]      FIG. 10  is another elevated view of an example cutting burr; and 
           [0018]      FIG. 11  is another elevated view of an example cutting burr. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    As used herein, the term “cutting burr” may be analogous with terms such as bit, drill bit, surgical drill bit and the like. The term “attachment” may have several meanings within the text of this application, but when generalized as a component of a surgical drilling instrument it refers to a portion of the instrument that attaches to the end of the motor/locking mechanism and receives the cutting burr. An “attachment” may be a controlled depth attachment, a minimally invasive attachment and the like. The surgical drilling instrument may include an integral motor (electric or pneumatic) and a locking mechanism and an attachment releasably connected to the locking mechanism. 
         [0020]    High speed surgical drills are increasingly being used by surgeons when performing delicate bone dissection in areas such as the cervical and lumbar spine. Such surgical drills operate at very high R.P.M., and are able to rotationally drive multiple types of attachments and cutting burrs. As will be described below, a cutting burr of the present disclosure includes a shank that defines two substantially diamond-shaped portions. The substantially diamond-shaped portions provide for ease of insertion and removal of the cutting burr to and from a compatible surgical drill. The substantially diamond-shaped portions also enable the surgical drill to direct higher levels of torque to the cutting burr during surgical procedures. 
         [0021]    Referring to  FIGS. 1-6 , the cutting burr is generally illustrated by reference numeral  10 . The attachment portion  12  of the shank  16  of the cutting burr  10  is generally shown as reference numeral  12 . A proximal end  14  of the shank  16  is formed with a pair of axially spaced six-sided diamond-shaped portions  18  and  20 . As shown in  FIGS. 4 and 5 , an upper surface of portion  18  includes an apex  32  and a pair of facets  34  and  34   a  also fairing to side edges  34   b  and  34   c.  The side edges  34   b  and  34   c  may be curved to match the radius of curvature of an outer surface of the shank  16 . As shown in  FIGS. 4 and 6 , an upper surface  24  of the portion  20  includes apex  26  and a pair of facets  30  and  30   a  fairing from the apex  26  to the side edges  30   b  and  30   c.  The side edges  30   b  and  30   c  may be curved to match the radius of curvature of an outer surface of the shank  16 . 
         [0022]    As shown in the Figs. the diametrical dimensions of the vertices in both portions is less than the diameter of the main body of the shank. The shank  16  may include an annular groove  29 . The lower surfaces of the pair of six-sided diamond portions  18  and  20  are a mirror image of the upper surface. While the diamond-shaped portions  18  and  20  are described as being “diamond-shaped,” it is noted that such terminology is intended to encompass any six-sided (hexagon) shape having a cross-section with flat edges that meet at a six vertices, curved edges that meet at six points, or some combination of both to form the six sides. The flat and curved edges, and combinations thereof, may be applied to other polygon shapes having different numbers of sides. 
         [0023]    The diamond-shaped portion  18  at the outermost proximal end is designed to be inserted into a mating drive portion of a surgical drill, as will be described with reference to  FIGS. 8A and 8B . The diamond-shaped portion  20  is provided as an abutment surface of a retractable locking pawl of the surgical drill to provide axial locking of the shank  16  within the surgical drill. The locking pawl may axially abut the adjacent abutment surface of the diamond-shaped portion  20  to axially lock the cutting burr  10  in place, thus providing substantially zero axial movement. For example, an engagement portion of locking pawl may be contoured having a generally V-shape with inner surfaces that fit against the facets  30  and  30   a  of the diamond-shaped portion  20 . 
         [0024]    As shown in  FIG. 3 , a back wall  42  may be formed perpendicular with relation to the central line A and faces a front wall  40  that is tapered from the facet (e.g.,  30   a ) to the outside diameter of the shank  16 . In accordance with some aspects, an engagement face of the locking pawl may abut against the back wall  42  to provide axial locking of the cutting burr  10  within the surgical drill. A tapered front wall  40  may facilitate the engagement of the locking pawl into the diamond-shaped portion  20 . 
         [0025]    The diamond-shaped portion  20  may also be engaged by a detent pawl of the surgical drill. For example, an engagement end of detent pawl may be contoured, e.g., having a generally hill shape to partially fit into the diamond-shaped portion  20  on an opposite side of the engagement end of the locking pawl. The detent pawl may be provided to apply a sufficient force on the diamond-shaped portion  20  to allow the cutting burr  10  to be moved in and out of the surgical drill, while reducing the likelihood that the cutting burr will inadvertently fall out of the surgical drill when in a loading position. 
         [0026]    As shown by the a comparison of the sectional views of the diamond-shaped portions  18  and  20  ( FIGS. 5 and 6 ), the two diamond shapes may be different in size, where the diamond shape in diamond-shaped portion  18  is larger than the diamond shape of the diamond-shaped portion  20 . As illustrated, the vertices  32  and  36  fall below the outer diameter of the shank  16  and both diamond shapes are in axial alignment with each other and may be oriented in parallel relationship. In some implementations, the diamond-shaped portion  20  and the diamond-shaped portion  18  may be the same size, or the diamond-shaped portion  18  may be larger than the diamond-shaped portion  20 . In the various configurations, the vertices  26  and  32  of diamond-shaped portions  20  and  18 , respectively, are along a same line and in a same plane as the center line A. Exemplary dimensions of the six-sided diamond diamond-shaped portions  18  and  20  are listed in degrees (°) and inches (″) and may be substantially as follows: 
         [0027]    The angle of the facets of the six-sided diamond in the diamond-shaped portion  20 −a=47°; 
         [0028]    The width of the facets of the six-sided diamond in the diamond-shaped portion  20 −b=0.046″; 
         [0029]    The width of the facets of the six-sided diamond in the diamond-shaped portion  18 −c=0.065″; 
         [0030]    The width of the shank  16  at the space between diamond-shaped portions  18  and  20 −d=0.029″; 
         [0031]    The length of the diamond-shaped portion  20 −e=0.068″; and 
         [0032]    The length between the proximal end and the back wall of diamond-shaped portion  18 −f=0.149″. This dimension may contribute to the feature of substantially reducing the axial play of the cutting burr. 
         [0033]    Thus, in accordance with the above, the diamond-shaped portions  18  and  20  provide sufficient cross-sectional dimensions to meet strength and reliability requirements needed for high-speed, large force surgical applications. Facets  34  and  34   a  of the diamond shape  18  provide positive engagement surfaces in both clockwise and counter-clockwise rotational directions and are sufficiently sized to withstand rotations forces in either direction without wobbling within the surgical drill. For example, some surgical drills provide bi-directional rotation, allowing the surgeon to selectively reverse rotation for various surgical techniques. In conventional designs, there may be rotational play between a bit end and a drive portion. However, the symmetrical diamond facets  34  and  34   a  of the diamond-shaped portion  18  provide substantial drive surfaces in either direction. 
         [0034]    With reference to  FIGS. 7A and 7B , the diamond-shaped portion  18  at the outermost proximal end of the cutting burr  10  is designed to have unidirectional backward compatibility with older drill instruments in accordance with aspects of the disclosure. For example, a conventional drill instrument may include an insert  106  that defines a generally rectangular slot  105  having rounded side walls. The rounded side walls may be shaped with a radius of curvature that parallels the outer wall of the insert  106 . Conventional cutting burrs may include a complementary generally rectangular portion having rounded side walls that is received by the slot  105 . The insert  106  may be driven by a motor, thus providing rotational force on the cutting burr. 
         [0035]    As shown in  FIG. 7A , in accordance with some implementations, facets  34   a  and  34   d  of the diamond-shaped portion  18  engage the inner walls of the slot  105 . The dimension c of the diamond-shaped portion  18 , noted above, may be sized such that the surface area of the facets  34   a  and  34   d  is substantial enough to withstand the torque provided by the motor of the conventional drill instrument. Thus, the cutting burr  10  of the present disclosure may be utilized by conventional drill instruments. 
         [0036]    Referring now to  FIGS. 8A and 8B , in some implementations, the cutting burr  10  of the present disclosure provides for a level of self-alignment within the insert  106 . The insert  106  may be provided in a compatible surgical drill and define a diamond-shaped key slot  107 , a pointed shaped inlet end  109 , and opposing holes  110  that formed in the insert  106  for receiving dowel pin which may serve to locate the cutting burr  10  when inserted into the key slot  107 . The inlet end  109  serves to facilitate the alignment and insertion of the cutting burr  10  as it is advanced toward and into the key slot  107  of the insert  106 . For example, if the diamond-shaped portion  18  is not in alignment with the key slot  107  ( FIG. 8A ), a bottom surface of the diamond-shaped portion  18  will contact an apex  111  of the inlet end  109  causing the cutting burr  10  to rotate into alignment with the key slot  107 . As such, the cooperative engagement of the diamond-shaped portion  18  and inlet end  109  facilitates the easy insertion of the cutting burr  10  into the compatible surgical drill. As such, the diamond portion  18  serves to provide a secure connection in the key slot  107 . 
         [0037]      FIGS. 9 ,  10 , and  11  illustrate different example cutting bits  22  provided at a distal end on the shank  16 . As described above, the shank  16  may include the attachment portion  12 . The cutting bits  22  may be milled or cut-out portions. The cutting burr  10  in  FIG. 9  exemplifies a fluted ball or drill bit; the cutting burr  10  in  FIG. 10  exemplifies a diamond ball; and the cutting burr  10  in  FIG. 11  exemplifies a twist drill. The cutting bits  22  are presented only as examples and are not intended to limit the scope of the present disclosure as numerous variations are possible. 
         [0038]    Thus, as described above, a cutting burr is provided with an attachment end that has a configuration and dimensions that serve to facilitate the insertion of the cutting burr into the surgical cutting instrument. When locked in the running position there is a structure that prevents the cutting burr from having any axial movement. Also, there is a positive connection such that the cutting burr rotates concentrically without any wobbling motion. 
         [0039]    While particular aspects of the present subject matter described herein have been shown and described, it will be apparent to those skilled in the art that, based on the teachings herein, changes and modifications may be made without departing from the subject matter described herein and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of the subject matter described herein.