Patent Abstract:
An articulating shaft includes an outer tubular member having a longitudinal axis and portions defining a slot. An inner tubular member is disposed within the outer member and movable about the axis of the outer member. A wedge carried by the inner member is movable within the slot in an interference fit with the slot portions to articulate the outer member. In an associated method, the inner member can be turned in a first direction to bend the outer member in an associated second direction, and the inner member can be turned in a third direction to move the outer member in an associated fourth direction.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a non-provisional application claiming the benefit of U.S. Provisional Patent Application Serial No. 60/460,487, filed on Apr. 3, 2003, and entitled Articulating Shaft, which is fully incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates generally to surgical instruments and more specifically to instruments having flexible or articulating shafts.  
           [0004]    2. Description of the Prior Art  
           [0005]    Surgical instruments, particularly those used in arthroscopic surgery, commonly are constructed with a shaft having a proximal end and a distal end. Some of these instruments have flexible shafts which permit them to be bent into a desired configuration. In most of these cases, the proximal end of a shaft is operable to articulate the distal end of the shaft.  
           [0006]    By way of example, it will be noted that in many arthroscopic surgeries it is necessary to introduce a forceps or some other instrument through a straight cannula. Once the tip of the instrument is inside the body it may be desirable to force a curve into the distal end so that the tip can cut, grab or perform some other function from a perspective not possible with a straight approach. Many instruments have a bend permanently set in the distal end; in order to accommodate such an instrument, a straight cannula with a very large diameter has been required.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    In accordance with at least one embodiment of the present invention, a flexible shaft is provided which can be controlled at the proximal end to flex or articulate the shaft at the distal end. It is of particular advantage that the shaft can be locked in the desired shape so that it maintains the shape while accommodating aggressive cutting or grabbing of the tissue. In one aspect of the invention, an articulating shaft has a distal end that is bendable by operation of a proximal end of the shaft. An outer member having an axis extending from the proximal end to the distal end is provided in the form of an outer tube. An inner tube is disposed within the outer tube. Portions of one of the inner tube and the outer tube define a slot having a first end and a second end wider then the first end. A wedge is carried by the other of the inner tube and the outer tube and is movable within the slot between the first end of the slot and the second end of the slot. The outer tube and the inner tube are operable at the proximal end to move the wedge within the slot toward the first end of the slot. This movement bends the tubes and articulates the distal end of the shaft.  
           [0008]    In one aspect of the invention, an articulating shaft with a proximal end and a distal end is bendable at the distal end by operation of the proximal end. The shaft includes an outer member having an axis extending from the proximal end to the distal end, the outer member having a configuration of a tube with a first longitudinal side and a second longitudinal side Portions of the first longitudinal side define a slot having a first end and a second end wider than the first end. An inner member is disposed within the outer member and carries a wedge that is movable within the slot between the first end of the slot and the second end of the slot. The inner member is operable at the proximal end of the shaft to move the wedge within the slot and toward the first end of the slot. This movement bends the outer tube away from the first longitudinal side and toward the second longitudinal side of the outer member.  
           [0009]    In another aspect of the invention, an outer tubular member has a longitudinal axis and portions defining a slot. An inner member is disposed within the outer member and movable about the axis of the outer member. A wedge is carried by the inner member and movable within the slot in an interference fit with the slot portions to bend the outer member.  
           [0010]    In another aspect of the invention, the inner member is disposed within the outer member and movable with a turn of a particular distance and a particular direction to produce in the outer member a bend having a magnitude and direction. The magnitude of the bend is dependent on the particular distance of the turn, and the direction of the bend is dependent upon the particular direction of the turn.  
           [0011]    In still a further aspect, the invention includes a method wherein an outer member is provided with a slot and an inner member is provided with a wedge. The inner member is mounted within the outer member with the wedge disposed in the slot. The outer member is bent in a first direction by turning the inner member in a second direction, while the outer member is bent in a third direction opposite to the first direction by turning the inner member in a fourth direction opposite to the second direction.  
           [0012]    These and other features and advantages of the invention will become more apparent with a description of preferred embodiments and reference to the associated drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a perspective view of one embodiment of the articulating shaft of the present invention;  
         [0014]    [0014]FIG. 2 is a perspective view of an outer tube illustrating the narrow end of slots formed in one longitudinal side of the tube;  
         [0015]    [0015]FIG. 3 is a perspective view of the outer tube showing a wide end of the slots formed in a second longitudinal side of the outer tube;  
         [0016]    [0016]FIG. 4 is a side elevation view showing the individual slots with a narrow end and a wide end;  
         [0017]    [0017]FIG. 5 is a top plan view illustrating a web disposed between the narrow ends of the opposed slots;  
         [0018]    [0018]FIG. 6 is a perspective view illustrating an inner tube in the embodiment of FIG. 1;  
         [0019]    [0019]FIG. 7 is a top plan view of the inner tube illustrating a web and bend stops associated with the slots;  
         [0020]    [0020]FIG. 8 is a wedge pads associated with the embodiment of FIG. 1;  
         [0021]    [0021]FIG. 9 is a perspective view of a wedge carried on a wedge pad of the inner tube;  
         [0022]    [0022]FIG. 10 is a top plan view of the wedge;  
         [0023]    [0023]FIG. 11 is a side elevation view of the wedge; and  
         [0024]    [0024]FIG. 12 is a perspective view of a bent shaft. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    A flexible or articulating shaft is illustrated in FIG. 1 and designated by the reference numeral  10 . In this embodiment, the shaft  10  includes an outer tube  12  and a coaxial inner tube  14  that are circumferentially moveable with respect to each other. The tubes  12  and  14  are disposed on a common axis  16 , which extends between a proximal end  18  and a distal end  21 .  
         [0026]    The outer tube  12  of this embodiment is illustrated in the perspective view of FIG. 2. In this view, it can be seen in the outer tube  12  has a pair of longitudinal sides  23  and  25  that are separated by a pair of webs  27  and  30 . A plurality of slots  32  are formed in the longitudinal side  25  and configured to extend circumferentially from a large end  34  to a narrow end  36 . Similar slots  38  are formed in the longitudinal side  23 . These slots  38  are formed as a mirror image of the slots  32  so that the narrow ends of the slots  32  and  38  are disposed in proximity to the web  27 , and the wide areas  34  of the slots  32  and  38  are formed in proximity to the web  30 . The outer tube  12  is rotated 180 degrees in the perspective view of FIG. 3 in order to better illustrate the wide end  34  of the slots  32  and  38  and the associated web  30 . A side elevation view showing the full length of the slots  32  is illustrated in FIG. 4, while the web  27  is best shown in the top plan view of FIG. 5.  
         [0027]    A preferred embodiment of the inner tube  14  is illustrated in the prospective view of FIG. 6. This inner tube  14  also has slots  40  and  42  which are disposed on opposing sides of webs  44  and  46 . In the illustrated embodiment, the slots  40  and  42  are similar in shape and have a generally constant width along their circumferential length.  
         [0028]    The slots  40  are defined by adjacent wedge pads  48  which extend circumferentially between the webs  44  and  46 . Similar wedge pads  51  define the opposing slots  42  which extend circumferentially between the webs  44  and  46 . A top plan view illustrated in FIG. 7 best shows the web  44  disposed between the slots  40  and  42 . From this view it can be appreciated that when the inner tube  14  is bent or articulated to the right in FIG. 7, the slots  40  close and form bend stops which inhibit overbending of the inner tube  14 . Similarly, if the inner tube  14  is bent to the left in FIG. 7, the slots  42  function as bend slots inhibiting overbending of the tube  14 .  
         [0029]    A plurality of wedge pads  48 , best illustrated in the side view of FIG. 8, provide substrates for the attachment of wedges  60 , best illustrated in FIG. 9. In this embodiment, the wedge pads  48  are each provided with a cylindrical surface  53  that is bounded by radial surfaces  55  and  57 . It is these cylindrical surfaces  53  of the wedge pads  48  which are configured to receive the wedges  60 . These wedges  60  can be adhered, welded, machined or otherwise disposed in a fixed relationship with an associated one of the cylindrical surfaces  53 . In a preferred embodiment, the wedge  60  has a broad end  62  and a narrow end  64  with side surfaces  66  and  68  which extend between a concave surface  71  and a convex surface  73 . These elements are also illustrated in the top plan view of FIG. 10. Of course, the wedges  60 ,  62  may have other than a triangular configuration; for example, a round pin may be of particular advantage in a different embodiment.  
         [0030]    With further reference to FIG. 1, it can be seen that when operatively disposed, the wedges  60  are mounted with the concave surface  71  fixed to the cylindrical surface  53  of the wedge pad  48 . Importantly, the wedges  60  are mounted within respected slots  32 , with the broad end  62  of the wedge  60  facing the wide end  34  of the slot  32  and the narrow end  64  of the wedge  60  facing the narrow end  36  of the slot  32 . Other wedges  62  are similarly disposed on the opposite side of the shaft  10  and oriented as a mirror image of the wedges  60  in the slots  42 .  
         [0031]    In operation, the inner tube  14  can be rotated relative to the outer tube  12  to move the wedges  60  and  62  within their respective slots  32  and  42 . When the inner tube is turned counterclockwise with respect to the outer tube  14 , the wedges  60  move toward the narrow end  36  of the slots  32 , upwardly in FIG. 1. As this movement occurs, the wedges  60  tend to separate the walls defining the slots  32 . As a result, the side of the tube  12  which has the slots  32  and the wedges  60 , tends to elongate. This same counterclockwise rotation moves the wedges  62  downwardly toward the broad end of the slots  42 . This permits the side of the tube  12  having the slots  42  and wedges  62  to contract. This opposing expansion and contraction articulates the outer tube  12  as well as the inner tube  14  so that the entire shaft  10  tends to bend away from the slots  32  and towards the slots  38 . It will be noted that the direction the inner tube  14  is turned is an angular direction, while the direction the outer tube  12  is bent is a linear direction.  
         [0032]    The opposite effect is achieved when the inner tube  14  is rotated clockwise with respect to the outer tube  12 . In this case, the wedges  62  move toward the narrow end of their slots  42  causing those slots to expand and the associated side of the tube  12  to elongate. The wedges  60  are moved toward the wider end of their slots  32  to permit contraction of their side of the tube  12 . As a result, the shaft  10  tends to articulate away from the slots  38  and towards the slots  32 . This articulation of the distal end  21  of the shaft  10  is accomplished merely by rotating the tubes  12  and  14  relative to each other at the proximal end  18  to the shaft  10 .  
         [0033]    In will be appreciated that in another embodiment of the invention, the tubes  12  and  14  could be switched. In such an embodiment, the wedges  60  and  62  would be carried on an inner surface of the outer tube and would be moveable within radial slots created in the inner tube.  
         [0034]    In another embodiment, the wedges  60  and  62 , could be replaced generally with any structure moveable within radial slots to alternatively expand and contract these slots on opposing sides of the shaft. As an example and not by way of limitation, the wedges  60  and  62  may be replaced with round pins, for instance.  
         [0035]    One advantage associated with the present invention relates to the tendency of the wedges  60  and  62  to remain at any given point within the associated slots  32 ,  34  until the tubes  12  and  14  are again actively rotated relative to each other. This locking feature of the associated embodiment, is achieved by the frictional resistance encountered between the wedges  60 ,  62  and the associated sides of their respective slots  32  and  38 . The locking feature can be further enhanced by adding frictional resistance in the form of detents located on the proximal control sections. In general, the locking feature permits the surgeon to articulate the shaft to a particular curve configuration and to know that the shaft  10  will retain that degree of curvature until it is changed by the surgeon.  
         [0036]    These features collectively permit the surgeon to introduce the shaft  10  through a small diameter straight cannula and then to operate the shaft  10  at the proximal end  18  to articulate the distal end  21 . When the desired degree of articulation is achieved, the relative rotation of the tubes  12  and  14  can be stopped and the locking feature relied on to maintain the desired bend through aggressive cutting and/or grabbing of the tissue.  
         [0037]    Thus, these and other modifications and additions will be obvious to those skilled in the art and may be implemented to adapt the present invention for use in a variety of different applications.

Technology Classification (CPC): 0