Abstract:
A hand-held surgical cutting instrument for cutting bone material with a surgical micro-saw blade has a plurality of openings formed therein. The surgical cutting instrument includes a hand-graspable body for manipulating the cutting instrument and a blade coupling mechanism attached to the body and being configured to attach to the surgical micro-saw blade. The blade coupling mechanism includes a first coupling member including a first blade-contacting surface. The first blade-contacting surface has at least one first protrusion extending therefrom and is configured to engage a first opening in the surgical saw blade. The blade coupling mechanism includes a second coupling member including a second blade-contacting surface facing the first blade-contacting surface of the first coupling member. The second blade-contacting surface having at least one second protrusion extending therefrom and configured to engage a second opening in the surgical saw blade.

Description:
RELATED APPLICATION 
     The present disclosure is related to commonly owned U.S. application Ser. No. 12/136,935, having the same filing date as the present application, titled, “Surgical Cutting Instrument with Near-Perimeter Interlocking Coupling Arrangement”, incorporated herein in its entirety by reference. 
     FIELD OF THE INVENTION 
     The present disclosure relates to a surgical cutting instrument, and more particularly, to a surgical cutting instrument with a dual surface interlocking coupling arrangement. 
     BACKGROUND 
     Bone-cutting surgical saws, such as sagittal or oscillating type surgical saws, cut most effectively at very high speeds, such as for example, 10000-40000 cycles per minute. These high speeds introduce high levels of vibration and can cause blade wander during a cut. Accordingly, actual blade cuts frequently have a thickness considerably greater than the thickness of the actual blade. For example, a cutting blade having a 0.015 inch thickness may be unable to cut a groove having a width of less than 0.030 inch. 
     Some vibration may be due to ineffective coupling systems. Coupling systems on conventional micro-saws clamp each side of the blade to rigidly secure the blade in place. Typical systems include protrusions on a bottom clamp that penetrate openings in the blade, and include an opposing top clamp that is smooth. Accordingly, only the bottom clamp holds the blade, while the top clamp is simply a smooth guide for blade placement. Over time, clamping forces may decrease, and because only one clamp secures the blade, the system becomes less stable, introducing additional vibration in the blade, and possibly resulting in less cutting effectiveness. 
     The devices disclosed herein overcome one or more of short-comings in the prior art. 
     SUMMARY 
     In one aspect, the present disclosure is directed to a hand-held surgical cutting instrument for cutting bone material with a surgical micro-saw blade having a plurality of openings formed therein. The surgical cutting instrument includes a hand-graspable body for manipulating the cutting instrument and a blade coupling mechanism attached to the body and is configured to attach to the surgical micro-saw blade. The blade coupling mechanism includes a first coupling member including a first blade-contacting surface. The first blade-contacting surface has at least one first protrusion extending therefrom and is configured to engage a first opening in the surgical saw blade. The blade coupling mechanism includes a second coupling member including a second blade-contacting surface facing the first blade-contacting surface of the first coupling member. The second blade-contacting surface has at least one second protrusion extending therefrom and is configured to engage a second opening in the surgical saw blade. 
     In another exemplary aspect, the present disclosure is directed to a hand-held surgical cutting system for cutting bone material. The system includes a surgical micro-saw blade having a distal end and a proximal end. The distal end has cutting teeth formed thereon and the proximal end has through-openings formed therein. The system also includes a surgical cutting saw including a hand-graspable body and a blade coupling mechanism attached to the body and configured to attach to the surgical micro-saw blade. The blade coupling mechanism includes a first coupling member including a first blade-contacting surface. The first blade-contacting surface has a first plurality of protrusions extending therefrom and is configured to engage openings in the surgical saw blade. The first plurality of protrusions are symmetrically disposed on the first blade-contacting surface. The blade coupling mechanism also includes a second coupling member including a second blade-contacting surface facing the first blade-contacting surface of the first coupling member. The second blade-contacting surface has a second plurality of protrusions extending therefrom and is configured to engage openings in the surgical saw blade. The second plurality of protrusions may be symmetrically disposed on the second blade-contacting surface and are offset from the first plurality of protrusions. 
     In yet another exemplary aspect, the present disclosure relates to a hand-held surgical cutting instrument for cutting bone tissue with a surgical micro-saw blade having openings formed therein. The surgical cutting instrument includes a hand-graspable body for manipulating the cutting instrument and a collet assembly attached to the body for attaching to the surgical micro-saw blade. The collet assembly includes a driving shaft including a head portion and a shaft portion. The head portion is removably connected to a first end of the shaft portion and includes a first blade-contacting surface facing the shaft portion. The blade-contacting surface has a first plurality of protrusions extending therefrom and is configured to engage the openings in the surgical saw blade. The collet assembly also includes a sleeve disposed about the driving shaft and is axially movable relative to the driving shaft. The sleeve includes a second blade-contacting surface facing the first blade-contacting surface. The second blade-contacting surface has a second plurality of protrusions extending therefrom and is configured to engage openings in the surgical saw blade. The first plurality of protrusions are offset from the second plurality of protrusions. At least one of the first and second blade-contacting surfaces includes a plurality of receiving recesses formed therein, the receiving recesses are sized and shaped to receive the respective protrusions of the other of the at least one of the first and second blade-contacting surfaces. 
     These and other features will become apparent from the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of an exemplary oscillating bone-cutting surgical system. 
         FIG. 2  is an illustration of a portion of an exemplary collet assembly from the surgical system of  FIG. 1  with a micro-saw blade. 
         FIG. 3  is an illustration of a cross-section of the exemplary collet assembly of  FIG. 2  with the micro-saw blade. 
         FIG. 4  is an illustration of the collet assembly of  FIG. 2  with a driving shaft head removed to show a blade-contacting surface on a sleeve. 
         FIG. 5  is an illustration of an exemplary driving shaft head of the collet assembly of  FIG. 2 , showing a blade-contacting surface. 
         FIG. 6  is an illustration of an exemplary driving shaft shank of the collet assembly of  FIG. 2 . 
         FIG. 7  is an illustration of an exemplary micro-saw blade from the bone-cutting surgical system of  FIG. 1 . 
         FIG. 8  is an illustration of an alternative embodiment of a driving shaft usable in an a collet assembly. 
         FIG. 9  is an illustration of an exemplary sagittal bone-cutting surgical system. 
     
    
    
     DETAILED DESCRIPTION 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to embodiments or examples illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alteration and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the disclosure relates. 
     Generally, the present disclosure relates to a bone cutting surgical system including a hand-held, high-speed, bone-cutting surgical saw, such as a sagittal or oscillating saw, and a cutting micro-saw blade. The saw includes a collet assembly with protrusions, such as pins or nubs, that mesh with or extend into openings on the cutting blade, thereby securing the blade in place in the collet assembly. In order to improve blade stability, the collet assembly disclosed herein includes protrusions that project into opening in the micro-saw blade from both the upper and lower sides. These offsetting protrusions may equalize the blade attachment, may reduce vibration, and may improve overall blade stability. In turn, this may improve cutting accuracy, which can reduce patient trauma and speed recovery time. 
     Turning now to  FIG. 1 , the present disclosure is directed to a bone-cutting surgical system  100  including a surgical saw  102  and a selectively removable micro-saw blade  104 . The surgical saw  102  includes a hand-piece  106 , a cord  108 , and a connector  110  configured to removably couple with a power source. The connector  110  is merely exemplary, and it should be apparent to one skilled in the art that any suitable connector may be used, and in some embodiments, the cord  108  itself may be coupled to the power source without the use of a connector. Additional contemplated embodiments include a power source as a part of the hand-piece  106 , such as a battery powered hand-piece. 
     The hand-piece  106  includes a motor assembly  112 , a grip  114 , and a collet assembly  116 . In some embodiments, the motor assembly  112  is housed within the grip  114 , while in other embodiments, it is disposed adjacent to the grip  114 . It is contemplated that any suitable system for controlling the surgical saw  102  may be used. For example, some embodiments include a trigger system disposed on the hand-piece  106  to provide hand-control of the cutting speed, or alternatively, a foot pedal associated with the hand-piece  106  through the power source to provide the controlling inputs. Other control systems also are contemplated. 
       FIGS. 2 and 3  show a portion of the exemplary collet assembly  116 , and  FIGS. 4-6  show collet assembly components. Referring to  FIGS. 2 and 3 , the collet assembly  116  secures the saw blade  104  to the surgical saw  102  and transfers a driving force from the motor to the blade. In this embodiment, it includes a driving shaft  118  and a sleeve  120  defining a longitudinal collet axis  122 . The sleeve  120  receives and extends about the driving shaft  118  and is axially movable along the collet axis  122  relative to the driving shaft  118 , enabling selective coupling with the blade  104 . It is contemplated that any suitable material may be used for the collet assembly  116 . In one embodiment, a biocompatible stainless steel material, such as Stainless 17-4 is used. 
     Referring to  FIGS. 3 and 4 , the sleeve  120  includes a head  124  and a shank  126 , with a central bore  128  extending therethough. In  FIG. 4 , a portion of the driving shaft  118  is disposed within the bore  128 . The bore  128  permits the sleeve  120  to move axially along the driving shaft  118 , enabling selective locking and releasing of the blade  104 . The head  124  includes a substantially planar blade-contacting surface  130  and an outer perimeter  132  adjacent the blade-contacting surface  130 . 
     The blade-contacting surface  130  includes a plurality of protrusions  134  formed thereon. These are symmetrically disposed about the collet axis  122  and are configured to interface with the saw blade  104 . Here, the sleeve  120  includes four protrusions  134  extending therefrom, spaced apart about the collet axis  122  at 90 degree intervals. It is contemplated that more or fewer protrusions  134  may be present. The protrusions  134  may be integrally formed with sleeve  120  or, for manufacturing convenience, may be separate components fit, such as with an interference fit, into receiving ports (not shown) formed in the blade-contacting surface  130 . In this embodiment, the protrusions  134  are rectangular projections having a height equal to or greater than the thickness of a corresponding saw blade  104 . In other examples however, the protrusions  134  have a circular, triangular, or diamond-shaped cross-section. Protrusions of other shapes are also contemplated. 
     In addition to the protrusions, the blade-contacting surface  130  includes a plurality of receiving recesses  136 . In  FIG. 4 , each of these are disposed between adjacent protrusions  134 , spaced symmetrically about the collet axis  122 . Like the protrusions  134 , the receiving recesses  136  are spaced 90 degrees apart. These have a depth less than the height of the adjacent protrusions, and as discussed below, are sized to receive protrusions on the driving shaft  118 . 
     The driving shaft  118  is shown in greater detail in  FIGS. 3 ,  5 , and  6 . Here, the driving shaft  118  includes a head  138  removably coupled to a distal end  139  of a shaft  140 . The shaft  140  defines a longitudinally extending shaft axis  142  ( FIG. 6 ). 
     Referring to  FIGS. 3 and 5  the head  138  includes a blade-contacting surface  144  and an outer perimeter  146 . Here, the blade-contacting surface  144  includes a central recess  148  for connecting with the distal end  139  of the shaft  140 . In this embodiment, the central recess  148  is square shaped. The distal end  139  of the shaft  140  also is grooved to be square-shaped so that when the driving shaft  118  is assembled, the head  138  is unable to rotate relative to the shaft  140 . A through hole  150  in the central recess  148  receives a fastener, such as a screw  150  (shown in  FIG. 2 ) that extends into a corresponding bore  152  in the end of the distal end  139  of the shaft  140  to fasten the head  138  to the shaft  140 . 
     The blade-contacting surface  138  also includes protrusions  154  formed thereon. Like those on the sleeve, these are symmetrically disposed about the collet axis  122  and are configured to interface with the saw blade  104 . Here, the head  138  includes four protrusions  154  extending therefrom, spaced apart at 90 degree intervals. It is contemplated that more or fewer protrusions  154  may be present. The protrusions  154  may be integrally formed with head  138  or may be separate components fit into receiving ports. Like those on the sleeve  120 , the protrusions  154  are rectangular projections having a height equal to or greater than the thickness of the corresponding saw blade  104 . Protrusions of other shapes are also contemplated. As discussed below, these protrusions are shaped and sized to fit into the receiving recess formed in the sleeve  120 . 
     The shaft  140  includes the distal end  139  either connected to or integral with the head  138  and includes a proximal end  156 . In this embodiment, the proximal end  156  includes a motor coupling feature  158  shown as a pin-receiving through passage that connects either directly or cooperatively to the motor to provide the cutting oscillation required. 
     Referring now to  FIG. 3 , as can be seen, the sleeve blade-contacting surface  130  and the driving shaft blade-contacting surface  144  face each other. The outer perimeter  146  of the head  138  is sized to have substantially the same diameter as the sleeve outer perimeter  132 . The sleeve  120  and driving shaft  118  may axially move apart to receive the blade  104 , and then come together to clamp the blade  104  between the blade-contacting surfaces  130 ,  144 . Although not shown, a spring force may be used to bias the sleeve  120  into a clamped position to secure any blade in place. 
       FIG. 7  shows the exemplary micro-saw blade  104  usable with the surgical saw  102  in  FIG. 1  and securable with the collet assembly  116  in  FIGS. 2-6 . The micro-saw blade  104  may be stamped and/or machined form a single material having a thickness in the range of 0.007-0.022 inch, for example. It includes a proximal end  180  that facilitates interconnection with the collet assembly  116  and a distal end  182  having a cutting edge including a plurality of cutting teeth  184  formed thereon. 
     In this example, the proximal end  180  is defined by a relatively bulbous head  186  that includes a slot  188  extending inwardly along a longitudinal axis  190  from the proximal end of the saw blade  104 . The slot  188  is formed with a funnel-like opening  192  defined by substantially straight edges  194  facing toward the longitudinal axis  190 . The straight edges  194  may help guide the saw blade  104  into place on the collet assembly  116 . A partially circular outer perimeter  196  defines an outer edge of the bulbous head  186 . In some embodiments, the outer perimeter  196  has a diameter substantially the same as, or slightly smaller than, the diameter of the driving shaft head  138  and the sleeve head  124 . 
     Openings  198  formed in the proximal end  180  permit the saw blade  104  to be secured to the surgical saw collet assembly  116 . In the embodiment shown, the openings  198  are symmetrically disposed about a center point  200 . Here, at least two openings  198  lie directly on opposing sides of the center point  200  and on transverse sides of the longitudinal axis  190 . A centrally disposed opening  198  lies along the longitudinal axis  190 . In the example shown the openings  198  are offset from each other by 45 degrees and are sized to match the protrusions  134 ,  154  on the driving shaft  118  and sleeve  120 . However, other offset angles are contemplated that match the desired collet assembly. 
     Here, each opening  198  is rectangular shaped in order to match the shape of the protrusions of the collet assembly  116 . In the example shown, the bulbous head  186  includes five openings  204 ,  206 . However, in other embodiments, more or less openings may be provided. When the funnel-like opening  192  has an angle smaller than that shown, additional openings may be included, while maintaining the 45 degree spacing shown. 
     Returning to  FIG. 3 , the collet protrusions interconnect with the saw blade  104  to secure it in place. The sleeve protrusions  134  extend upwardly in  FIG. 3 , through the openings  198  and abut against the blade-contacting surface  144 . Likewise, although not visible in  FIG. 3 , the driving shaft protrusions  154  extend downwardly through the openings  198  and into the receiving recesses  136  in the sleeve  120 . Accordingly, in the saw blade embodiment having five openings  198  as in  FIG. 7 , either two or three protrusions pass through the blade openings  198  from the bottom and either two or three protrusions pass through the blade openings  198  from the top. Because the sleeve protrusions  134  are spaced 90 degrees apart and the driving shaft protrusions  154  are spaced 90 degrees apart, but offset from the sleeve protrusions by 45 degrees, the blade  104  can be removed and secured in the collet assembly in eight different positions. In some embodiments, for example, the collet assembly includes a total of only four protrusions or six protrusions, and the openings on the blade  104  are chosen to correspond with the protrusions. Other amounts of protrusions are contemplated. 
     In addition to securing the saw blade  104  in place with the protrusions  134 ,  154 , the blade-contacting surfaces  130 ,  134  also frictionally engage and reduce vibration and play. Accordingly, it may be beneficial to provide as much contact area between the blade and blade-contacting surfaces as is practicable. Accordingly, in the embodiment shown, the protrusions  134 ,  154  are formed with rectangular cross-sections instead of circular cross-sections. Rectangular shaped protrusions can have the same maximum width as a corresponding cylindrical protrusions for stability, but permits an overall increase in the blade surface area that interfaces with the blade-contacting surfaces  130 ,  144 . This too may help more solidly secure the blade  104  in place in the collet assembly  116 . 
       FIG. 8  shows an alternative driving shaft  250 . Here the driving shaft includes the shaft  140 , but includes an alternative head  252 . Because many of the features of the head  252  are similar to those discussed above, only the differences will be discussed in detail. Here, in addition to having rectangular protrusions  254 , the head  252  includes a plurality of receiving recesses  256 . Each of these are disposed between the adjacent protrusions  254 , and spaced symmetrically about a driving shaft axis  258 . The protrusions  254  are spaced 90 degrees apart, and the receiving recesses are spaced 90 degrees apart. These receiving recesses  256  are shaped differently than the corresponding protrusions on the sleeve  120  however. These receiving recesses  256  are shaped with a curved inner end and parallel sides that extend entirely to an outer perimeter  260 . Accordingly, in use with this embodiment, the sleeve protrusions  134  may extend entirely through the blade openings  198 , but instead of abutting directly against the blade-contacting surface of the driving shaft, the sleeve protrusions project into the receiving recesses  256 . 
     It should be noted that in some embodiments, the receiving recesses on the head may be shaped and sized similar to those described relative to the sleeve  120 , but that any suitable size and shape may be used. 
       FIG. 9  shows a sagittal saw  300  for driving the saw blade  104 . In this embodiment, a collet assembly  302  is arranged to secure the blade  104  in an axial direction relative to a saw handle  304 . Accordingly, in this embodiment, the collet assembly  302  includes side-by-side blade-contacting surfaces. However, like the oscillating saw  102  disclosed in  FIGS. 1-6 , the sagittal saw  300  includes protrusions disposed on both blade-contacting surfaces adjacent an exterior edge of the collet fixture, and the blade  104  is sized so that the outer perimeter of the head of the saw blade substantially corresponds to the edge of the collet assembly. 
     Although only a few exemplary embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this disclosure. Accordingly, all such modifications and alternatives are intended to be included within the scope of the invention as defined in the following claims. Those skilled in the art should also realize that such modifications and equivalent constructions or methods do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.