Abstract:
An adjustable cam and follower system for a surgical device that includes a tri-dimensional rotatable cam member having a rotational input and a cam surface, the contour of which is defined by at least one radius of varying length. The system further includes a follower selectively moveable linearly, the follower configurable to ride substantially upon the cam surface as the cam rotates. A handpiece having an ergonomic member attachable thereto is also disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority to U.S. provisional application 60/580,068 filed on Jun. 16, 2004 and U.S. provisional application 60/503,056 filed on Sep. 15, 2003, both of which are incorporated herein by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention generally relates to the field of surgical cutting instruments and, more particularly, to surgical instruments having a selectively adjustable reciprocating cutter.  
         [0004]     2. Description of the Related Art  
         [0005]     Cam systems are often used in machines to convert rotary motion into linear motion. One type of cam system uses a rotating cam to linearly drive a follower. In a particular implementation, the follower is held in constant contact with a surface of the cam by a biasing force, typically applied by a spring or an air cylinder. The shape of the rotating cam is generally configured to control the linear motion of the follower. The cam is typically oblong with respect to its rotational axis and has “high” and “low” points on a surface thereof. When the cam rotates to a “low” point or position, the biasing force pushes the follower toward the cam and the center of rotation. In contrast, when the cam rotates to a “high” point or position, the follower is extended away from the center of rotation, compressing the spring. Thus, a continuously rotating cam may be used to produce a linear reciprocating motion in the follower.  
         [0006]     In surgical cutting instruments for excising tissue, an elongated handpiece is generally included. A typical handpiece is cylindrical in design and is intended to be held by a surgeon in the same manner as a pencil. Within the surgical cutting instrument cam systems are typically used to reciprocatingly drive a surgical cutting member. In a typical instrument design, the cam is rotatively driven by a motor that resides in the handpiece of the instrument. Unfortunately, the cam systems in conventional surgical cutting instruments are limited in that the operating plane of the surgical cutting member is fixed in relation to the rotational axis of the cam. In other words, the angle of the surgical cutting member cannot be adjusted relative to the handpiece. Among other limitations, the inability to adjust the angle between the surgical cutting member and the handpiece may impair a surgeon&#39;s visual access to the surgical site. Furthermore, the inability to modify the cutting member angle relative to the handpiece precludes a surgeon from adjusting the surgical instrument to ergonomically fit his/her hand. Moreover, although the method of holding the handpiece in the same manner as a pencil is intuitive, it does not provide the best control when manipulating the handpiece during long and/or awkward surgical procedures.  
         [0007]     In an attempt to improve control, various surgical instruments have been developed having a tapered handpiece and/or other features, such as ridges, knurls or bumps, that facilitate a surgeon&#39;s grip on the handpiece. While these features may improve a surgeon&#39;s ability to hold the surgical device, they fail to alleviate hand fatigue that may complicate and/or lengthen the surgical procedure. Accordingly, an improved surgical cutting instrument is desired that provides a surgeon with the ability to adjust the angle of a cam driven reciprocating cutting member relative to a handpiece of the instrument and reduce hand fatigue associated with the conventional surgical cutting instruments.  
       SUMMARY  
       [0008]     An adjustable cam and follower system for a surgical device is provided that includes a tri-dimensional rotatable cam member having a rotational input and a cam surface, the contour of which is defined by at least one radius of varying length. The system further includes a follower selectively moveable linearly, the follower configurable to ride substantially upon the cam surface as the cam rotates. Accordingly, the cam and follower system produces smooth reciprocating movement in the follower. In an embodiment, the cam and follower system is contained within a handpiece having an ergonomic member attachable thereto. The cam and follower system improves ergonomics for a surgeon by enabling the surgeon to adjust the angle of the surgical device thereby modifying the cutting angle of the surgical device. Furthermore, the ergonomic member enables a reduction in hand fatigue by enabling better control when manipulating the surgical device during surgical procedures. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein:  
         [0010]      FIG. 1  is a schematic illustration of a cam surface according to an embodiment of the invention.  
         [0011]      FIG. 2  is a cross-sectional view of a rotatable cam member according to an embodiment of the invention.  
         [0012]      FIG. 3  is a cross-sectional view of a rotatable cam member according to another embodiment of the invention.  
         [0013]      FIG. 4  is a cross-sectional view of a rotatable cam member according to another embodiment of the invention.  
         [0014]      FIGS. 5A and 5B  are cross-sectional views of a rotatable cam member according to another embodiment of the present invention.  
         [0015]      FIGS. 6A and 6B  are partial cross-sectional views of a cam and follower system according to an embodiment of the present invention.  
         [0016]      FIGS. 7A and 7B  are partial cross-sectional views of a cam and follower system according to another embodiment of the present invention.  
         [0017]      FIGS. 8A-8C  are partial cross-sectional views of a fixture demonstrating the adjustment of the follower angle in a cam and follower system according to an embodiment of the present invention.  
         [0018]      FIG. 9  is a partial cross-sectional view of a surgical cutting instrument employing a cam and follower system according to an embodiment of the present invention.  
         [0019]      FIG. 10  is an illustration of a prior art intracranial surgical handpiece used in a medical procedure.  
         [0020]      FIG. 11  is an illustration of a surgical handpiece used in a medical procedure employing the cam and follower system according to an embodiment of the present invention.  
         [0021]      FIG. 12  is a side view of a surgical device including an ergonomic attachment according to an embodiment of the present invention.  
         [0022]      FIG. 13  is a side view of the ergonomic attachment of  FIG. 12 .  
         [0023]      FIG. 14  is a front view of the ergonomic attachment of  FIG. 12 .  
         [0024]      FIG. 15  is a perspective view of the surgical device and ergonomic attachment of  FIG. 12 , shown in a surgeon&#39;s hand.  
         [0025]      FIG. 16  is a side view of a surgical device including an ergonomic attachment according to another embodiment of the present invention.  
         [0026]      FIG. 17  is a front view of the ergonomic attachment of  FIG. 16 .  
         [0027]      FIG. 18  is perspective view of the ergonomic attachment of  FIG. 16 .  
         [0028]      FIG. 19  is a perspective view of the surgical device and ergonomic attachment of  FIG. 16 , shown in a surgeon&#39;s hand. 
     
    
     DETAILED DESCRIPTION  
       [0029]     Referring now to the drawings, the illustrative embodiments of the present invention are shown in detail. Although the drawings represent some preferred embodiments of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain the present invention. Further, the embodiments set forth herein are not intended to be exhaustive or otherwise limit or restrict the invention to the precise forms and configurations shown in the drawings and disclosed in the following detailed description.  
         [0030]     Referring to  FIG. 1 , a schematic representation of a cam surface  10 ,  10 ′ is shown according to an embodiment of the present invention. The surface  10 ,  10 ′ of the cam is defined by a radius  12 ,  12 ′ rotated about a central surface point  14 ,  14 ′, which is shown as being two different points in  FIG. 1  but is actually a ring having a radius  16 . In this regard, central surface point  14 ,  14 ′ is displaced at a fixed distance  16  from the cam&#39;s axis of rotation  18  along a plane  19  that is perpendicular to axis  18 . Accordingly, radius  12 ,  12 ′ varies as central surface point  14 ,  14 ′ is rotated about axis  18 .  
         [0031]     Referring to  FIG. 2 , a cross-sectional view of a rotatable cam member according to an embodiment of the present invention is shown. The rotatable cam member includes a cam surface  20 ,  20 ′, a stem  22  and a hub  24  connecting cam surface  20 ,  20 ′ to stem  22 . Cam surface  20 ,  20 ′ also includes upper and lower transition surfaces  26 , which taper according to the contour of cam surface  20 ,  20 ′ as radius  12 ,  12 ′ is varied.  
         [0032]     Referring to  FIG. 3 a  cross-sectional view of a rotatable cam member according to another embodiment of the invention is shown. The illustrated embodiment is substantially similar to the embodiment shown in  FIG. 2  with at least one exception, namely, cam surface  30 ,  30 ′ does not extend below plane  19 .  
         [0033]     Referring to  FIG. 4 a  cross-sectional view of a rotatable cam member according to another embodiment of the invention is shown. The illustrated embodiment is substantially similar to the embodiment shown in  FIG. 2  with at least one exception, namely, cam surface  32 ,  32 ′ does not extend below plane  19  and does not extend radially outwardly from axis  18  a distance greater than radius  16 .  
         [0034]     In  FIGS. 2-4 , transition surface  26  illustrates how radius  12  is smoothly reduced to radius  12 ′ as central surface point  14 ,  14 ′ is rotated about axis  18 . However, the invention is not limited to the embodiments shown in  FIGS. 2-4 . Alternatively, radius  12 ,  12 ′ may vary in length and/or contour as central surface point  14 ,  14 ′ is rotated about axis  18  to provide a cam member having the desired cam surface profile.  
         [0035]     Referring to  FIGS. 5A-5B , a rotatable cam member is shown according to another embodiment of the invention. In the illustrated embodiment, the rotatable cam member includes a body  40  having a cam surface  42  and an axis of rotation  18 . Cam body  40  may include a stem  43  configured for attachment to the rotational output of a drive member, such as a motor or transmission. Surface  42  is similar to surface  30 ,  30 ′ described above in reference to  FIG. 3  and is configured to interface with a follower, as will be described below.  FIG. 5A  shows the rotatable cam member in a first angular position and  FIG. 5B  shows the rotatable cam member in a second angular position about 180 degrees opposite the first position.  
         [0036]     Referring to  FIGS. 6A and 6B , a cam and follower system according to an embodiment of the invention is shown. The cam and follower system includes a selectively adjustable follower  44  shown in contact with cam surface  42 . In each of  FIGS. 6A and 6B , follower  44  is shown in two positions. In either position, follower  44  is free to translate along the axis of the follower, but is otherwise prohibited from moving relative to the rotatable cam member.  
         [0037]      FIG. 6A  shows the cam body  40  in a first angular position. In this position, follower  44  is shown contacting cam surface  42  at exterior contact point  46  and at an interior contact point  48 . Contact points  46  and  48  are in a region of cam body  40  where the outer portion of cam surface  42  is defined by the longest radius  12  and thus, follower  44  is generally at a distance equal to radius  12  from central surface point  14 .  
         [0038]      FIG. 6B  shows the cam body  40  in a second angular position rotated about 180 degrees about the axis of rotation  18 . Follower  44  is shown in  FIG. 6B  as contacting the cam surface  42 ′ at exterior surface point  46 ′ and at interior surface point  48 ′. At this angle of rotation, cam surface  42 ′ is defined by the shortest radius  12 ′. When cam body is rotated to the second angular position shown in  FIG. 6B , the tip of follower  44  is closer to central surface point  14 ′ than it was to central surface point  14  when cam body  40  was in the first angular position shown in  FIG. 6A . Thus, as cam body  40  is rotated, follower  44  translates reciprocatingly along the axis of the follower to produce a reciprocating output  50 . The distance of reciprocation is roughly the difference in length between radius  12  and radius  12 ′. The cam surface between radii  12  and  12 ′ is defined by a continuously smooth transition as cam body  40  is rotated about axis of rotation  18 , which produces smooth reciprocating movement in follower  44 .  1   
         [0039]     As noted above, follower  44  may be moved about central surface point  14 ,  14 ′ along an arc  52 . Since cam surface  42 ,  42 ′ is defined by the rotation of radius  12 ,  12 ′ about central surface point  14 ,  14 ′, the position of follower  44  may be moved about an arc  52  without substantially changing the characteristics of reciprocating output  50 . Thus, the position of follower  44  relative to cam body  40  is adjustable without significantly changing the stroke length of the reciprocating output  50 .  
         [0040]      FIGS. 7A and 7B  illustrate a cam and follower system according to another embodiment of the present invention. In the illustrated embodiment, the cam and follower system includes a cam body  54  that is substantially similar to cam body  40  described above with at least one exception, namely, cam body  54  includes a smaller cam surface  55 ,  55 ′ similar to cam surface  32 ,  32 ′ shown in  FIG. 4 . As with the cam and follower system described above with respect to  FIGS. 6A and 6B , the position of follower  44  is movable relative to cam body  54  along an arc  52 , albeit with a more limited range of motion due to the smaller cam surface  55 ,  55 ′.  
         [0041]     Referring still to  FIGS. 7A and 7B , a slew angle  56  may be introduced into the position of follower  44  relative to cam body  54  without significantly effecting operation of the cam and follower system. More particularly, slew angle  56  is the angle of follower  44  with respect to cam body  54  that is created by movement of follower  44  about a point  58 ,  58 ′ on cam surface  55 ,  55 ′, rather than by movement of follower  44  about central surface point  14 ,  14 ′. When follower  44  is moved about a point other than central surface point  14 ,  14 ′, the stroke length of reciprocating output  50  may change. However, the end of follower  44  that contacts surface  55 ,  55 ′ may be configured to reduce the impact of slew angle  56  in the system.  
         [0042]      FIG. 8A-8C  illustrate a fixture for holding a rotatable cam member  62  and adjustable angle follower  44  according to an embodiment of the present invention. The fixture emphasizes a feature of the present invention in that it allows the output angle  64 ,  64 ′ of follower  44  to be changed without significantly changing the stroke length of the reciprocating output  50 . Particularly,  FIG. 8A  is a top view of the cam and follower system, wherein follower  44  is adjusted to an angle  64  relative to the axis of rotation  18  of cam member  62 . Angle  64  of follower  44  may be adjusted at a pivot point  66 , such as a hinge, which is substantially aligned with the central surface point of the cam surface. When angle  64  is adjusted, the reciprocating output  50  and stroke length remain virtually unchanged. For reference,  FIG. 8B  illustrates the side view of the fixture described by  FIG. 8A .  
         [0043]      FIG. 8C  illustrates the cam and follower system shown in  FIGS. 8A and 8B , wherein the follower  44  is positioned substantially parallel to the axis of rotation  18  and thus, the angle  64 ′ of follower  44  relative to the axis of rotation  18  of cam member  62  is approximately 180 degrees. While  FIGS. 8A-8C  generally illustrate the cam and follower configuration shown in  FIGS. 7A-7B , the illustrated fixture shown in  FIGS. 8A-8C  is also applicable to rotatable cam members shown in  FIGS. 1-6B .  
         [0044]      FIG. 9  illustrates the cam and follower system according to an embodiment of the present invention integrated into an adjustable surgical device  70 . Surgical device  70  includes a handpiece  72  that provides the necessary support for a cam body  74 , a follower  44 , a biasing mechanism  75 , a hinge  76 , which permits the follower angle  52  to be adjusted, and a rotational output  78  coupled to an electric motor  80 . The rotational output  78  rotatingly drives cam body  74 , which in turn drives follower  44  as described above. Follower  44  is attached to a cutting member  82  that includes an outer cannula and an inner cutting cannula. Follower  44  provides the reciprocating motion to move the inner cutting cannula within the outer cannula. An aspiration line  84  may be connected to a vacuum source for extracting fluids or tissue from a patient. In addition, aspiration line  84  may be used to introduce fluids for anesthesia or irrigation of the surgical site. The cam and follower system allows a surgeon to adjust the angle  52  of the cutting member  82  relative to the remaining of handpiece  72 , which improves the ergonomics and control of handpiece  72  and reduces hand fatigue.  
         [0045]      FIG. 10  shows a typical surgical site access region  90  for intracranial surgery on a patient  92 .  FIG. 10  also illustrates a typical non-adjustable surgical device  94  configured such that the reciprocating output  50  is parallel to the axis of reciprocation  96 . The surgical site  98  is substantially blocked by handpiece  94  and hinders the surgeon&#39;s view of surgical site  98  or the surgeon&#39;s ability to bring other instruments into the region  90 .  
         [0046]      FIG. 11  illustrates an adjustable surgical device  70  according to an embodiment of the present invention that allows a surgeon to adjust the angle of reciprocating output  50  relative to handpiece  72 . In addition to improving the ergonomics of surgical device, the ability to adjust the cutting member  82  relative motor housing portion of the handpiece  72  permits less obscured access into region  90 .  
         [0047]     The adjustable angle cam and follower system of the present invention, when integrated into a surgical handpiece, improves ergonomics for the surgeon by providing adjustment of the handpiece in relation to the axis of surgical entry. The surgeon is then able to preferentially adjust the angle of the reciprocating output for more comfortable holding of the handpiece. Further, the stability of the handpiece is improved by allowing the surgeon to hold the handpiece body at a preferred angle relative to the axis of surgical entry and improve access into the surgical region during a surgical procedure.  
         [0048]     Now referring to  FIG. 12 , the exemplary surgical device  70  is illustrated. As discussed above, surgical device  70  includes the handpiece  72  and a surgical tool portion  100  that extends from a distal end  102  of handpiece  72 . Tool portion  100  may be configured for, but is not limited to, cutting, excising, ablating and irrigating. In the illustrated surgical device  70 , a cable  104  extends from a proximal end  106  of handpiece  72  to provide, for example, power, rotational input and/or an aspiration line.  FIG. 12  also illustrates an embodiment of an ergonomic attachment  108  particularly, but not necessarily, suited for use with handpiece  72 .  
         [0049]     In the illustrated embodiment shown in  FIGS. 12-14 , ergonomic attachment  108  includes a connecting portion  110  and an extension portion  112 . In a particular configuration, connecting portion  110  includes a generally U-shaped groove  114  within which the cylindrical handpiece  72  is received (see, e.g.,  FIG. 14 ). The inner surface of receiving groove  114  is generally contoured to closely match the outer surface of handpiece  72 . As shown in  FIG. 14 , ergonomic attachment  108  may include a channel  116  below groove  114  sized to allow passage of an aspiration line, electrical cable and the like.  
         [0050]     Ergonomic attachment  108  may be made of a rigid, yet slightly resilient material, such as plastic, which allows connecting portion  110  to be “snapped” onto handpiece  72 . The resiliency of the material and/or the contour of the inner surface of groove  114  can be tailored to allow adjustable movement of ergonomic attachment  108  along the axis of handpiece  72  with minimal effort. Optionally, the interface between receiving groove  114  and handpiece  72  may be configured to allow predefined locational placement of ergonomic attachment  108  on handpiece  72 . Either or both of connecting portion  110  and handpiece  72  may include, for example, grooves, ridges, bumps, dimples and other suitable features that provide a detent or other feature that creates one or more predefined locational positions. However, other approaches for removably and/or adjustably securing ergonomic attachment  108  to handpiece  72 , such as hook-and-loop style fasteners, for example, are also within the scope of present invention.  
         [0051]     Ergonomic attachment  108  may be readily removed from surgical device  70  and replaced with a different ergonomic attachment to accommodate a different hand size or preference. Depending on the manner in which connecting portion  110  is affixed to handpiece  72 , ergonomic attachment  108  may be removed by sliding connecting portion  110  off of an end of handpiece  72 . Alternatively, ergonomic attachment  108  may be removed by applying a pivoting force down and away from handpiece  72 , thus providing a “snap off” detachment. In another embodiment, ergonomic attachment  108  may be integrally formed with handpiece  72  and or non-removably attached thereto.  
         [0052]     As noted above, ergonomic attachment  108  may be attached by forcing handpiece  72  into groove  114 , thus providing a “snap on” attachment. Alternately, ergonomic attachment  108  may be attached to handpiece  72  by sliding connecting portion  110  axially onto handpiece  72 .  
         [0053]     Extension portion  112  extends from connecting portion  110  at a predetermined angle, creating a shelf-like support that rests on top of a surgeon&#39;s hand (see, e.g.,  FIG. 15 ). The angle (X) by which extension portion  112  extends from connecting portion  110  can vary depending on the shape and size of the surgeon&#39;s hand, and is generally, but not necessarily, in the range of about 0° to 45°.  
         [0054]     As shown in  FIG. 15 , a surgeon may grip handpiece  72  or any other comfortable surface on surgical device  70 , including connecting portion  110  of ergonomic attachment  108 . Extension portion  112  may be positioned at any point along the length of handpiece  72  from distal end  102  to proximal end  106 . Intermediate positions are achieved by sliding connecting portion  110  along handpiece  72 . Allowing movement of ergonomic attachment  108  along the length of handpiece  72  enables the surgeon to determine the most comfortable position for ergonomic attachment  108  during the surgical procedure. Ergonomic attachment  108  can be readily moved at any time during a surgical procedure to provide additional comfort or, if desired, removed entirely.  
         [0055]     During a surgical procedure, extension portion  112  rests on the surgeon&#39;s hand  118  and helps stabilize surgical device  70 . By spreading the weight of surgical device  70  over a portion of the surgeon&#39;s hand  118 , ergonomic attachment  108  removes some of the weight of the surgical device from the surgeon&#39;s fingers, which allows the surgeon use of his fingers to maneuver the surgical device with more precision and control. Ergonomic attachment  108  also reduces hand fatigue associated with the surgeon&#39;s use of his fingers to support the weight of surgical device  70  and control its movement.  
         [0056]     Referring to  FIGS. 16-19 , another embodiment of the present invention is shown. In this embodiment, an ergonomic attachment  120  is provided that is removably attached to surgical device  70 . Ergonomic attachment  120  is generally spherical in shape and includes a groove  122  disposed therein that receives handpiece  72 . The inner surface of receiving groove  122  is generally contoured to closely match the contour of the outer surface of handpiece  72 .  
         [0057]     Ergonomic attachment  120  may be made of a rigid, yet slightly resilient material, such as plastic, which allows it to be “snapped” onto handpiece  72 . The resiliency of the material and/or the contour of the inner surface of groove  122  can be tailored to allow adjustable movement of ergonomic attachment  120  along the axis of handpiece  72  with minimal effort. Optionally, the interface between receiving groove  122  and handpiece  72  may be configured to allow predefined locational placement of ergonomic attachment  120  on handpiece  72 . Either or both of connecting portion  110  and handpiece  72  may include, for example, grooves, ridges, bumps, dimples and other suitable features that provide a detent or other feature that creates one or more predefined locational positions. However, other approaches for removably securing ergonomic attachment  120  to handpiece  72 , such as hook-and-loop style fasteners, for example, are also within the scope of present invention.  
         [0058]     Ergonomic attachment  120  may be readily removed from surgical device  70  and replaced with a different ergonomic attachment to accommodate a different hand size or preference. Depending on the manner in which ergonomic attachment  120  is affixed to handpiece  72 , ergonomic attachment  120  may be removed by sliding off of an end of handpiece  72  or, alternatively, by applying a pivoting force down and away from handpiece  72 , thus providing a “snap off” detachment. In still another embodiment, ergonomic attachment  120  may be integrally formed with handpiece  72  and or non-removably attached thereto.  
         [0059]     As shown in  FIG. 19 , a surgeon may grip handpiece  72  or any other comfortable surface on surgical device  70 , including ergonomic attachment  120 . Ergonomic attachment  120  may be positioned at any point along the length of handpiece  72  from distal end  102  to proximal end  106 . Intermediate positions are accomplished by sliding ergonomic attachment  120  along handpiece  72 . Allowing movement of ergonomic attachment  120  along the length of handpiece  72  enables the surgeon to decide the most comfortable position for ergonomic attachment  120  during the surgical procedure. Ergonomic attachment  120  can be readily moved at any time during a surgical procedure to provide additional comfort or, if desired, removed entirely. Ergonomic attachment  120  allows the surgeon to support surgical device  70  with all of the fingers on a given hand, removing some or all of the weight of surgical device  70  from his index finger and thumb. This reduction in weight allows the surgeon use of his thumb and/or fingers to maneuver the surgical device with more precision and control.  
         [0060]     The present invention has been particularly shown and described with reference to the foregoing embodiments, which are merely illustrative of the best modes for carrying out the invention. It should be understood by those skilled in the art that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention without departing from the spirit and scope of the invention as defined in the following claims. It is intended that the following claims define the scope of the invention and that the apparatus within the scope of these claims and their equivalents be covered thereby. This description of the invention should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements. Moreover, the foregoing embodiments are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application.