Patent Publication Number: US-2023144990-A1

Title: Ultrasonic surgical instrument and method for manufacturing same

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an ultrasonic surgical tool or instrument. This invention also relates to a method for manufacturing the tool or instrument. 
     U.S. Pat. No. 6,379,371 discloses an ultrasonic surgical blade, particularly for cutting bone tissue, which has a blade body with a smooth continuous cutting edge and a shank connected at one end to the blade body and operatively connectable at an opposite end to a source of ultrasonic vibrations. The shank is provided with an axially extending bore for the conveyance of cooling fluid to the cutting edge, while the blade body is provided with an axially extending through-slot communicating at one end with the bore. The blade body is preferably provided at an end opposite the shank with a recess communicating, with the bore for distributing fluid from the slot towards the cutting edge. The recess preferably has a configuration which parallels at least a portion of the cutting edge. Where the cutting edge is circular and the blade body has a planar surface between the fluid distribution guide surface and the cutting edge, for instance, the recess has a fluid distribution surface inclined with respect to the planar blade surface and extending along a circular arc. 
     In the manufacture of such a bone-cutting instrument, the blade body is generated separately and then affixed to the end of a tubular shaft. Thus there is a joint between the instrument shaft or horn and the blade. 
     OBJECTS OF THE INVENTION 
     It is an object of the present invention to provide an improved ultrasonic instrument particularly a bone-cutting blade. 
     Another object of the present invention is to provide such a tool or instrument wherein joints are reduced if not eliminated. 
     A further object of the present invention is to provide such a tool or instrument wherein manufacture is facilitated. 
     It is a concomitant object of the present invention to provide such a tool or instrument which may be produced at less expense than existing instruments. 
     Yet another object of the present invention is to provide a method for manufacturing an ultrasonic bone cutting instrument or tool. 
     These and other objects of the invention will be apparent to those skilled in the art from the drawings and descriptions hereof. Although each object is attained by at least one embodiment of the invention, no embodiment need necessarily meet every object. 
     SUMMARY OF THE INVENTION 
     An ultrasonic surgical instrument in accordance with the present invention comprises a cylindrical shaft and a blade at a distal or free end of the shaft, the blade being unitary and continuous with the shaft, without an intervening joint. As discussed hereinafter, the manufacture of this instrument entails machining a distal end of a tool blank and particularly a distal end portion of a shaft thereof. 
     The surgical instrument typically further comprises a radially or transversely enlarged proximal end portion at a proximal end of the shaft opposite the blade. The enlarged proximal end portion is configured for attachment to an electromechanical transducer device such as a piezo-electric stack housed inside an instrument hand piece. 
     Pursuant to a further feature of the present invention, the shaft has a longitudinal axis and the blade includes a flat or planar blade body with a proximal end eccentrically disposed relative to the shaft axis. Thus, the blade body or at least a proximal end portion thereof is disposed eccentrically relative to the shaft. 
     Pursuant to another feature of the present invention, the blade body has at least one edge or peripheral surface that is a cylindrical section continuous and coaxial with a cylindrical outer surface of the shaft. 
     In one embodiment of the present invention, the blade body extends in a plane parallel to the shaft axis. 
     The shaft has an end face contiguous with the proximal end of the blade body and also has a channel or bore with an outlet in the end face. 
     According to another aspect of the present invention, where the blade body has a major lateral surface facing the axis, the blade body is provided in the major lateral surface with a groove continuous with the channel or bore at the outlet thereof. The groove may extend the length of the blade body to a distal end of the blade body. Alternatively, where the blade body is provided with a through slot or hole, the groove extends from the outlet of the shaft channel or bore to a proximal side of the through slot or hole. 
     The blade body may be provided at a distal end, opposite the shaft, with a beveled surface inclined with respect to the axis. Alternatively or additionally, the blade body may be formed with an arcuate distal tip, where the distal tip has a circular or cylindrical surface with an axis oriented perpendicular to the shaft axis. 
     In a second embodiment of the present invention, the blade body extends at an angle with respect to the axis and intersecting the shaft axis. Where the shaft has an end face contiguous with the proximal end of the blade body and additionally has a channel or bore with an outlet in the end face, the blade body has a planar first major lateral surface and a planar second major lateral surface facing oppositely to one another. 
     Pursuant to another feature of the present invention, the blade body is provided in the first major lateral surface with a groove continuous with the channel or bore at the outlet. The blade body may be further provided with a through hole at an end of the groove opposite the end face and the outlet, the groove extending from the outlet to the through hole. The second major lateral surface may formed with an additional groove communicating with the through hole. The additional groove is preferably tapered from a wide end at the through hole and a closed narrow end at the second major lateral surface. The second major lateral surface may take the form of an annular oval surface with an oval center edge formed by the through hole and the additional groove. 
     The blade body of this second embodiment may have an endless peripheral or perimetric surface continuous with a cylindrical outer surface of the shaft, the peripheral or perimetric surface being a cylindrical section coaxial with the outer surface of the shaft. 
     The present invention is also directed to a method for manufacturing a unitary ultrasonic surgical instrument having a shaft portion and a blade portion at a distal of free end of the shaft, the blade being unitary and continuous with the shaft, without an intervening joint. The method comprises providing a tool blank including an enlarged connector portion at one end and a cylindrical shaft at an opposite end and machining a distal end portion of the cylindrical shaft on opposing sides thereof to form the shaft portion from the cylindrical shaft and to generate two opposing flats. The formation of the flats may realize the blade portion as a planar shaft extension or end portion having at least one edge surface that is a cylindrical section continuous and coaxial with a cylindrical outer surface of the shaft portion. 
     The machining of the distal end portion of the cylindrical shaft preferably includes rotating a cutting tool about a rotation axis extending parallel to at least one of the flats. 
     The machining of the distal end portion of the cylindrical shaft typically includes forming an end surface of the shaft portion as a cylindrical section having an axis parallel to the rotation axis and one or both flats. 
     The present invention provides an ultrasonic instrument, particularly an ablation or bone-cutting instrument that is more easily manufactured and that can have tighter or more consistent specifications. Thus quality control is facilitated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an isometric view of an ultrasonic surgical instrument or probe pursuant to the present invention. 
         FIG.  2    is an isometric view, on a larger scale, of a distal end portion of the instrument or probe of  FIG.  1   . 
         FIG.  3    is a side elevational view of the distal end portion of  FIG.  2   . 
         FIG.  4    is a top plan view of the distal end portion of  FIGS.  2  and  3   . 
         FIG.  5    is a bottom plan view of the distal end portion of  FIGS.  2 - 4   . 
         FIG.  6    is a longitudinal cross-sectional view of a tubular tool blank schematically illustrating two envelopes of cutting tool paths on an upper side and a lower side, in a method for manufacturing the instrument or probe of  FIGS.  1 - 5   , in accordance with the present invention. 
         FIG.  7    is an isometric view of a distal end portion of another ultrasonic surgical instrument or probe pursuant to the present invention. 
         FIG.  8    is a side elevational of the distal end portion of  FIG.  7   . 
         FIG.  9    is an isometric view of a distal end portion of a further ultrasonic surgical instrument or probe pursuant to the present invention. 
         FIG.  10    is a side elevational of the distal end portion of  FIG.  9   . 
         FIG.  11    is an isometric view of a distal end portion of an additional ultrasonic surgical instrument or probe pursuant to the present invention. 
         FIG.  12    is a side elevational of the distal end portion of  FIG.  11   . 
         FIG.  13    is an isometric view of a distal end portion of yet another ultrasonic surgical instrument or probe pursuant to the present invention. 
         FIG.  14    is a side elevational of the distal end portion of  FIG.  13   . 
         FIG.  15    is an isometric view of a distal end portion of yet a further ultrasonic surgical instrument or probe pursuant to the present invention. 
         FIG.  16    is a side elevational of the distal end portion of  FIG.  15   . 
     
    
    
     DETAILED DESCRIPTION 
     Each of the ultrasonic surgical instrument embodiments illustrated in the drawings comprises a cylindrical shaft and a blade at a distal of free end of the shaft, the blade being unitary and continuous with the shaft, without an intervening joint. The manufacture of these instruments entails machining a distal end of a tool blank and particularly a distal end portion of a tubular shaft thereof. 
     As depicted in  FIG.  1   , a surgical instrument  20  comprises a cylindrical shaft  22  and a blade  24  at a distal or free end of the shaft, the blade being unitary and continuous with the shaft, without an intervening joint. Instrument  20  (and all of the instruments disclosed herein) typically further comprises a radially or transversely enlarged proximal end portion  26  at a proximal end of the shaft  22  opposite blade  24 . Proximal end portion  26  is configured for attachment to an electromechanical transducer device (not shown) such as a piezo-electric stack housed inside an instrument hand piece (not shown). 
     Shaft  22  has a longitudinal axis  28  and blade  24  includes a flat or planar blade body  30  with a proximal end  32  eccentrically disposed relative to shaft axis  28 . Thus, blade body  30  or at least a proximal end portion thereof is disposed eccentrically relative to shaft  28 . 
     In each embodiment of an ultrasonic surgical instrument disclosed herein, a blade includes a flat or planar blade body with a proximal end eccentrically disposed relative to a shaft axis. Thus, the blade body or at least a proximal end portion thereof is disposed eccentrically relative to the instrument shaft. 
     As illustrated In  FIGS.  2 - 4   , blade body  30  has at least one edge or peripheral surface  34  that is an endless cylindrical section or perimetral surface continuous and coaxial with a cylindrical outer surface  36  of shaft  22 . 
     Each embodiment of an ultrasonic surgical instrument disclosed herein has a blade body with at least one edge or peripheral surface in the form of a cylindrical section continuous and coaxial with a cylindrical outer surface of the instrument shaft. 
     As illustrated in  FIG.  6   , a method for manufacturing surgical instrument  20  comprises providing a tool blank  38  including an enlarged connector portion  26  ( FIG.  1   ) at one end and a cylindrical shaft  40  at an opposite end and machining a distal end portion  42  of the cylindrical shaft on opposing sides (not designated) thereof to form the shaft portion  22  ( FIG.  1   ) of instrument  20  from cylindrical shaft  40  of the blank  38  and to generate two opposing flats or major blade surfaces  44  and  46 . The formation of flats  44  and  46  realizes the blade portion  24  ( FIGS.  1 - 5   ) as a planar shaft extension or end portion having edge or peripheral surface  34 . 
     As illustrated in  FIG.  3   , blade body  30  extends at an angle a 1  with respect to shaft axis  28  and intersects the shaft axis. Shaft  22  has an end face  48  contiguous with the proximal end  32  of blade body  30  and additionally has a channel or bore  50  with an outlet  52  in the end face  48 . Flats  44  and  46  are a planar first major lateral surface and a planar second major lateral surface facing oppositely to one another. 
     It is to be noted that a rotating cutting tool (schematically depicted at  49 ) is used to cut flats  44  and  46  from distal end portion  42  ( FIG.  6   ) of blank  38 . The rotating cutting tool has a circular or cylindrical cutting face (not separately designated) that is moved along a first linear path  51  ( FIG.  6   ) so as to exhibit an oblate oval cutting envelope  54 , as shown in  FIG.  6   . Shaft end face  48  is formed simultaneously with the formation of a proximal end portion of flat  44  by the same cutting action and accordingly takes the form of a cylindrical section. Of course, end face  48  may be separately and additionally machined in a supplemental process to provide the end face with a planar form. 
     The same rotating cutting tool  49  may be used to form lower flat  46 , as schematically indicated by another oblate oval cutting envelope  56 , as shown in  FIG.  6   . 
     As depicted in  FIGS.  2  and  4   , blade  24  is provided in flat or major lateral surface  44  with a groove  150  continuous with a channel or bore  50  at outlet  52 . Blade  24  is further formed so as to exhibit a through hole  152  at an end of groove  150  opposite end face  48  and outlet  52 . Groove  150  extends from outlet  52  to through hole  152 . As shown in  FIG.  5   , flat or major lateral surface  46  is formed with an additional groove  154  communicating with through hole  152 . Groove  154  is tapered from a wide end at through hole  152  and a closed narrow end  156  at flat or major lateral surface  46 . Surface  46  is in the form of an annular oval surface with an oval center edge  158  formed by through hole  152  and groove  154 . 
     In each of the embodiments of  FIGS.  7 - 16   , a blade extends parallel to an axis of an elongate linear instrument shaft and to one side of that axis. Accordingly, each blade body necessarily has a proximal end that is unitary with the distal end of the shaft at a point that is eccentrically disposed relative to the shaft, i.e., at a distance from the shaft axis. The various blades are produced by machining a blank in the form of a tubular rod with a cutting tool having a circular cutting edge or cylindrical cutting surface, with that cutting tool being moved along a path parallel to the shaft axis. The distal end faces of the shafts may have a cylindrically concave surface produced by the circular or cylindrical cutting tool or may be flat as illustrated, which shape is rendered by further machining, for instance, by moving the circular or cylindrical cutting surface along a linear path at an angle from the shaft axis. 
     As depicted in  FIGS.  7  and  8   , a surgical instrument  60  comprises a cylindrical shaft  62  and a blade  64  at a distal or free end of the shaft, the blade being unitary and continuous with the shaft, without an intervening joint. Instrument  60  further comprises a radially or transversely enlarged proximal end portion  26  ( FIG.  1   ) at a proximal end of the shaft  62  opposite blade  64  or connecting to an electromechanical transducer device (not shown) such as a piezo-electric stack housed inside an instrument hand piece (not shown). 
     Blade  64  has a planar upper major surface  66  facing an axis  68  of instrument shaft  62  and a planar lower major surface  70  facing in the opposite direction, away from axis  68 . Surfaces  66  and  70  are parallel to one another and to axis  68 . Blade  64  is spaced at such a distance from axis  68  that no groove is formed in upper surface  66 . A channel or lumen  72  of shaft  62  has an outlet port  74  over a proximal end of surface  66  so that irrigant flowing under pressure through the channel or lumen empties out onto surface  66 . Blade  64  has a distal end face  76  that is flat and oriented perpendicularly to shaft axis  68 . Blade  64  has a pair of lateral peripheral edge surfaces  78  that are cylindrical sections continuous and coaxial with an outer surface (not separately designated) of shaft  62 . 
     As illustrated in  FIGS.  9  and  10   , a surgical instrument  80  comprises a cylindrical shaft  82  and a blade  84  at a distal or free end of the shaft, the blade being unitary and continuous with the shaft, without an intervening joint. Instrument  80  further comprises a radially or transversely enlarged proximal end portion  26  ( FIG.  1   ) at a proximal end of the shaft  82  opposite blade  84  or connecting to an electromechanical transducer device (not shown) such as a piezo-electric stack housed inside an instrument hand piece (not shown). 
     Blade  84  has a planar upper major surface  86  facing an axis  88  of instrument shaft  82  and a planar lower major surface  90  facing in the opposite direction, away from axis  88 . Surfaces  86  and  90  are parallel to one another and to axis  88 . Blade  84  is spaced at such a distance from axis  68  that an elongate groove  91  is formed in upper surface  86 . Groove  91  is continuous and coaxial with a cylindrical surface (not separately designated) of a channel or lumen  92  of shaft  82  and communicates with the channel or lumen via an outlet port  94  thereof. During use of the instrument  80 , irrigant flows under pressure through channel or lumen  92  and empties into groove  91 , from which the irrigant is distributed over surface  86 . Blade  84  has a beveled distal end face  96  that is flat with a straight terminal edge  93  and rounded corners  95  and oriented at an angle to shaft axis  88 . Groove  91  terminates in or at beveled distal end face  96 . Blade  84  has a pair of lateral peripheral edge surfaces  98  that are cylindrical sections continuous and coaxial with an outer surface (not separately designated) of shaft  82 . 
       FIGS.  11  and  12    depict a surgical instrument  100  that is identical to instrument  80  except for the provision of a through slot  102  in blade  84 . Reference numbers in  FIGS.  11  and  12    are the same as those designating like features or elements of surgical instrument  80 . Slot  102  is formed in groove  91 , essentially midway along the length thereof, and divides the groove into a proximal groove segment  104  and a distal groove segment  106 . Slot  102  facilitates the flow of irrigant from groove  91  or groove segment  104  to under surface  90 . 
     As shown in  FIGS.  13  and  14   , a surgical instrument  110  comprises a cylindrical shaft  112  and a blade  114  at a distal or free end of the shaft, the blade being unitary and continuous with the shaft, without an intervening joint. Instrument  110  further comprises a radially or transversely enlarged proximal end portion  26  ( FIG.  1   ) at a proximal end of the shaft  112  opposite blade  114  or connecting to an electromechanical transducer device (not shown) such as a piezo-electric stack housed inside an instrument hand piece (not shown). 
     Blade  114  has a planar upper major surface  116  facing an axis  118  of instrument shaft  112  and a planar lower major surface  120  facing in the opposite direction, away from axis  118 . Surfaces  116  and  120  are parallel to one another and to axis  118 . Blade  114  is spaced at such a distance from axis  118  that a short groove section  121  is formed in upper surface  116 , where the groove section is continuous and coaxial with a cylindrical surface (not separately designated) of a channel or lumen  122  of shaft  112  and communicates with the channel or lumen via an outlet port  124  thereof. Blade  114  is also provided with an elongate through slot  126  extending parallel to shaft axis  118 . At a distal end of through slot  126 , blade  114  has a distal groove section  128  that extends from slot  126  on one side to a circular edge or cylindrical end surface  130  on an opposite side. Blade  114  has a pair of lateral peripheral edge surfaces  132  that are cylindrical sections continuous and coaxial with an outer surface (not separately designated) of shaft  112 . 
     During use of the instrument  110 , irrigant flows under pressure through channel or lumen  122  and into proximal groove section  121  and then into slot  126  from which the irrigant may exit onto both major blade surfaces  116  and  120  and to circular edge or cylindrical end surface  130 . 
       FIGS.  15  and  16    depict a surgical instrument  140  that is identical to instrument  110  except for a beveling at the distal end of the instrument. Reference numbers in  FIGS.  15  and  16    are the same as those designating like features or elements of surgical instrument  110  in  FIGS.  13  and  14   . Instrument  140  has a beveled end surface  142 . Distal groove section  128  is truncated by the formation of beveled end surface  142  and exhibits a tapering which facilitates distribution of irrigant from slot  126  over beveled end surface  142 . 
     It is evident that in each of the instrument embodiments disclosed herein, the instrument shaft  22 ,  62 ,  82 ,  112  has an end face  48 ,  144 ,  146 ,  148  contiguous with a proximal end of the blade  25 ,  64 ,  84 ,  114  and also has a channel or bore  50 ,  72 ,  92 ,  122  with an outlet  52 ,  74 ,  94 ,  114  in that end face. The blade  25 ,  64 ,  84 ,  114  may be provided in a major lateral surface or flat  44 ,  86 ,  116  with a groove  91 ,  104 ,  121  continuous with the channel or bore  50 ,  92 ,  122  at the outlet  52 ,  94 ,  114  thereof. The groove  91  may extend the length of the blade to a distal end of the blade. Alternatively, where the blade  24 ,  84 ,  114  is provided with a through slot or hole  102 ,  126 , the groove includes a section  104 ,  121  extending from the outlet  94 ,  124  of the shaft channel or bore  92 ,  112  to a proximal side of the through slot or hole  102 ,  126 . The blade  84 ,  140  may be provided at a distal end, opposite the shaft  82 ,  112 , with a beveled surface  96 ,  142  inclined with respect to the axis  88 ,  143  ( FIG.  16   ). Alternatively or additionally, the blade  24 ,  114  may be formed with an arcuate distal tip, where the distal tip has a circular or cylindrical surface with an axis oriented perpendicular to the shaft axis. 
     As discussed hereinabove with reference to  FIG.  6   , a method for manufacturing a unitary ultrasonic surgical instrument having a shaft portion  22 ,  62 ,  82 ,  112  and a blade portion  24 ,  64 ,  84 ,  114  at a distal of free end of the shaft comprises providing a tool blank  38  including an enlarged connector portion  26  at one end and a cylindrical shaft  40  at an opposite end and machining a distal end portion  42  of the cylindrical shaft on opposing sides thereof to form the shaft portion  22 ,  62 ,  82 ,  112  from the cylindrical shaft and to generate two opposing flats  44 ,  66 ,  86 ,  116  and  46 ,  70 ,  90 ,  120 . The formation of the flats  44 ,  66 ,  86 ,  116  and  46 ,  70 ,  90 ,  120  realizes the blade portion  24 ,  64 ,  84 ,  114  as a planar shaft extension or end portion that may have at least one edge surface  34 ,  78 ,  98 ,  132  that is a cylindrical section continuous and coaxial with a cylindrical outer surface of the shaft portion  22 ,  62 ,  82 ,  112 . The machining of the distal end portion  42  of the cylindrical shaft  40  of the tool blank  38  typically includes rotating cutting tool  49  about a rotation axis extending parallel to at least one of the flats  44 ,  66 ,  86 ,  116  (perpendicular to the plane of the drawing in  FIG.  6   ). Distal end portion  42  of the cylindrical shaft  40  of the tool blank  38  may be further machined along edge surfaces  34 ,  78 ,  98 ,  132 , for instance, to taper the blade portion  24 ,  64 ,  84 ,  114 , that is to reduce the free-end width thereof. 
     The machining of the distal end portion  42  of the cylindrical shaft  40  typically includes forming an end surface  48 ,  144 ,  146 ,  148  of the shaft portion  22 ,  62 ,  82 ,  112  as a cylindrical section (not shown) having an axis parallel to the rotation axis of the tool  49  and one or both flats  44 ,  66 ,  86 ,  116  and  46 ,  70 ,  90 ,  120 . Further machining, either with tool  49  or a different tool can be undertaken to form shaft end surfaces  48 ,  144 ,  146 ,  148  as flat or planer surfaces inclined with respect to shaft axes  28 ,  68 ,  88 ,  118 . 
     Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.