Abstract:
In one aspect there is a curved medical instrument comprising an outer member and an inner member. The inner member has a curved portion at a distal region of the inner member. The outer member is concentrically and movably coupled to the inner member and has a flexible transmission mechanism at a distal region of the outer member. The flexible transmission mechanism transmits a linear and/or rotational actuating force along the curved portion of the instrument. The inner member can include an opening configured to receive a target for cutting, such as a flexible fixating member and/or biological tissue.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates to medical devices, and more particularly to transmitting an actuating force along a curved instrument.  
         BACKGROUND  
         [0002]    To assist a surgeon when performing a meniscal repair, there is a knot pusher and suture cutter with a straight distal end. The straight suture cutter includes two components at its distal end, one inside the other. The inner component has a hollow tip at the distal end so a surgeon can pass a suture through the tip and out a port on the side of the inner component. The tip of the inner component is designed to push a knot and or receive an attachment to push a knot. The outer component slides over the straight inner component and cuts any suture protruding from the port of the inner component.  
         SUMMARY  
         [0003]    The present application teaches a medical instrument with a curved distal end and a flexible transmission mechanism to transmit an actuating force along that curved distal end. The flexible transmission mechanism is able to negotiate or manage the connection of rigid components over a curved axis. The mechanism permits smooth translation between the rigid elements and an actuating mechanism, between which the flexible transmission mechanism is disposed.  
           [0004]    For example, the mechanism allows concentric actuating tube(s) to follow along a rigid, yet curved axis. In one example, the actuating translation is achieved by the placement of strategic relief geometry along the body of a mating component to generate the flexible transmission mechanism. This strategic geometry creates the relief and clearance necessary for the concentrically mating member to transfer linear and/or rotary motion along the curved portion in a smooth translation without binding. The distal working end of the device is curved so that it may provide accessibility to the desired areas that may be inaccessible by traditional non-invasive means. The curved portion negotiates the working trajectory, such as in the application of maneuvering and or accommodating anatomical structures.  
           [0005]    In one aspect, there is a medical instrument including an inner member and an outer member. The inner member has a curved portion at its distal region. The outer member is concentrically and movably coupled to the inner member. The outer member includes a flexible transmission mechanism at its distal region. The medical instrument can have one or more of the following features. The flexible transmission mechanism of the outer member can have less material than another portion of the outer member that is less flexible than the flexible transmission mechanism. The outer member can include a wall defining a passage through which the inner member passes. In this example, the wall of the flexible transmission mechanism does not fully enclose the passage of the outer member. In one example, the wall of the flexible transmission mechanism of the outer member can be disposed on a concave side of the curved portion of the inner member. In another example, the wall within the flexible transmission mechanism of the outer member can enclose approximately a range of 30% to 40% of the circumference of the passage.  
           [0006]    The outer member can include a first less-flexible portion and a second less-flexible portion. The first less-flexible portion is disposed distal to the flexible transmission mechanism. The second less-flexible portion is disposed proximal to the flexible transmission mechanism. The flexible transmission mechanism is configured to conform to the curved portion while transferring motional forces from the second less-flexible portion to the first less-flexible portion. The motional forces can include linear and/or rotational forces. The outer member can include a first portion and a second portion. The first portion includes a first lumen through which a portion of the inner member passes. The second portion includes a second lumen through which a portion of the inner member passes. In this example, the flexible transmission mechanism is disposed between the first portion and the second portion. The first portion can include a cutting surface disposed distal to the flexible transmission mechanism.  
           [0007]    The medical instrument can also include a first cylindrical portion within the inner member and a second cylindrical portion within the outer member. In this example, the first cylindrical portion is disposed concentrically within the second cylindrical portion. The inner member can also include an opening configured to receive a target. The opening can be disposed distal to the curved portion. The cutting surface of the outer member and an edge of the opening can include a sharp edge. The target can include suture and/or biological tissue. The distal end of the inner member can be configured to push a knot. The distal end of the inner member can include a rounded edge. The medical instrument can also include an actuating member coupled to at least one of the inner member and the outer member.  
           [0008]    In another aspect, there is a medical instrument including an outer member and an inner member. The outer member has a passage extending therethrough. The inner member is slidably positioned within the passage. The inner member includes a curved portion at its distal region and an opening within the distal region for receiving a target. The inner member and outer member are configured such that when at least one of the inner member and the outer member moves, the target positioned within the opening is cut between an edge of the outer member and an edge of the opening. The medical instrument can include one or more of the following features. The outer member can include a flexible portion at a distal region of the outer member. The edge of the outer member can be disposed distal to the flexible member.  
           [0009]    The flexible portion of the outer member can have less material than another portion of the outer member that is less flexible than the flexible portion. The passage can include a wall defining the passage. In this example, the wall does not fully enclose the passage within the flexible portion of the outer member. The wall of the flexible portion of the outer member can be disposed on a concave side of the curved portion of the inner member. The wall within the flexible portion of the outer member encloses approximately a range of 30% to 40% of the circumference of the passage. The outer member can include a first less-flexible portion and a second less-flexible portion. The first less-flexible portion includes the edge of the outer member, and is disposed distal to the flexible member. The second less-flexible portion is disposed proximal to the flexible portion. In this example, the flexible portion is configured to conform to the curved portion while transferring motional forces from the second less-flexible portion to the first less-flexible portion. The motional forces can include linear and/or rotational forces.  
           [0010]    The outer member can include a first portion and a second portion. The first portion includes a first lumen through which a portion of the inner member passes. The second portion includes a second lumen through which a portion of the inner member passes. In this example, the flexible portion is disposed between the first portion and the second portion. The first portion can include the edge of the outer member and can be disposed distal to the flexible portion. The medical instrument can include a first cylindrical portion within the inner member and a second cylindrical portion within the outer member. In this example, the first cylindrical portion is disposed concentrically within the second cylindrical portion.  
           [0011]    The opening can be disposed on a side of the inner member in contact with the outer member. The opening can be disposed at a distal end of the curved portion. The opening can be disposed distal to the curved portion. The edge of the outer member and/or the edge of the opening can include a sharp edge. The distal end of the inner member can be configured to push a knot. The distal end of the inner member can include a rounded edge. The medical instrument can also include an actuating member coupled to at least one of the inner member and the outer member. The target can include suture and/or biological tissue.  
           [0012]    In another aspect, there is a method for generating a curved medical instrument. The method includes bending an inner member to form a curve at a distal region of the inner member and providing an outer member with a passage, where the passage is sized to allow the inner member to pass therethrough. The method also includes removing a portion of a wall of the outer member at a distal region of the outer member. The method can also include providing the inner member with an opening, where the opening sized to receive a target, and where bending further comprises bending the inner member to form a curve proximal to the opening.  
           [0013]    The method can also include providing a cutting surface adjacent the opening. The method can also include providing a cutting surface on the outer member adjacent the removed portion of the wall. The method can also include providing a cutting surface at a distal end of the outer member. The method can also include locating the inner member concentrically within the outer member. The method can also include coupling an actuating member to the inner member and/or the outer member. The method can also include rounding an edge of a distal tip of the inner member.  
           [0014]    In another aspect, there is a method for using a curved medical instrument. The method includes moving an outer member and/or an inner member concentrically disposed within the outer member, to cause the outer member to slide over an opening disposed distal to a curved portion of the inner member and to cut a target extending through the opening. In an example where the target include a flexible fixating member, such as suture, the method can also include threading the flexible fixating member through the opening of the inner member. The method can also include pushing a knot with a distal end of the inner member. The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
       
    
    
     DESCRIPTION OF DRAWINGS  
       [0015]    [0015]FIG. 1A is a side view of a curved medical instrument.  
         [0016]    [0016]FIG. 1B is a close-up view of the distal end of the curved medical instrument of FIG. 1A.  
         [0017]    [0017]FIG. 2A is a side view of an inner member of the curved medical instrument.  
         [0018]    [0018]FIG. 2B is a front view of the inner member of FIG. 2A.  
         [0019]    [0019]FIG. 2C is a top view of the inner member of FIG. 2A.  
         [0020]    [0020]FIG. 2D is a cross-sectional side view of the inner member of FIG. 2C.  
         [0021]    [0021]FIG. 2E is a perspective view of the inner member of the curved medical instrument.  
         [0022]    [0022]FIG. 3A is a side view of an outer member of the curved medical instrument.  
         [0023]    [0023]FIG. 3B is a cross-sectional transverse view of portions of the outer member of FIG. 3A.  
         [0024]    [0024]FIG. 3C is a top view of the outer member of FIG. 3A.  
         [0025]    [0025]FIG. 3D is a cross-sectional front view of a flexible portion of the outer member.  
         [0026]    [0026]FIG. 4A is a side view of the inner member and the outer member during a cutting process.  
         [0027]    [0027]FIG. 4B is a side view of another example of the inner member and the outer member during a cutting process. 
     
    
       [0028]    Like reference symbols in the various drawings indicate like elements.  
       DETAILED DESCRIPTION  
       [0029]    [0029]FIG. 1A illustrates a curved medical instrument  100  that serves both as a suture cutter and a knot pusher. The distal end of instrument  100  has a curved inner member  105 , which is positioned within an outer member  150 . Curved inner member  105  is cylindrical in shape and has a channel through which a surgeon threads suture  110 . The surgeon introduces suture  110  into the channel through an opening at the distal tip  115  and exits at an opening  120 , located on the side of inner member  105 . In operation, the surgeon pulls suture  110  in the direction of arrow  125  while moving instrument  100  in the direction of arrow  130  until distal tip  115  touches knot  135 . The surgeon continues moving instrument  100  in the direction of arrow  130 , while pulling suture  110  in the direction of arrow  125 . This pushes knot  135  in the direction of arrow  130  towards surgical site  140 . This allows the surgeon to tension a pre-tied knot  135  or tie a knot outside of the body and push knot  135  to surgical site  140  within the body to secure the repair.  
         [0030]    Once knot  135  is in place to secure the repair, the surgeon uses instrument  100  to cut any excess suture  110 . The surgeon slides trigger  145  towards the distal end of instrument  100 . Trigger  145  connects to the cylindrical outer member  150  and moves outer member  150  towards the distal end of instrument  100 . Outer member  150  is configured, as described below, such that it can conform to the curve of inner member  120  while sliding along and over inner member  120 . Outer member  150  slides over curved inner member  105  and eventually reaches opening  120 . As outer member  150  slides over opening  120 , the distal tip of outer member  150  pinches suture  110  against a distal side of opening  120 , cutting suture  110  at opening  120 , as will be described in more detail below. FIG. 1B illustrates a close-up view of the distal end of instrument  100 .  
         [0031]    As described above, outer member  150  slides along and over curved inner member  105 , which includes distal tip  115  for pushing knot  135  and opening  120  through which suture  110  passes. FIGS.  2 A-F illustrate the inner member  105  in more detail. FIG. 2A shows inner member  105  removed from medical instrument  100 . As shown, inner member  105  includes a curved portion  205  at a distal region. As show in FIG. 2B, distal tip  115  of inner member  105  includes an opening  210  through which the surgeon threads the suture  110 . The diameter of opening  210  is sized so that it is not much larger than the diameter of suture  110 . This allows suture  110  to pass freely through opening  210 , but prevents a knot (e.g., knot  135 , FIG. 1) from passing through opening  210 . Instead, wall material  215  pushes the knot while the surgeon pulls a single thread of suture  110  through opening  210 . There are other possible configurations for distal tip  115 , as described in the alternatives below.  
         [0032]    As shown in FIG. 2C, the distal end of opening  120  includes a cutting surface  220  against which suture  110  is pushed during the cutting process. Cutting surface  220  can also include a sharp edge to assist in the cutting process. FIGS. 2D and 2E illustrate a channel  225  through which suture  110  passes when the surgeon is pushing a knot as described above. Wall material  215  at distal tip  115  is rounded.  
         [0033]    As described above, outer member  150  slides along and over inner member  105  during the cutting process. FIGS.  3 A-D illustrate outer member  150  in more detail. FIG. 3A shows the outer member  150  removed from medical instrument  100 . As shown, the distal region of outer member  150  includes a flexible portion  305  that accommodates and conforms to curved region  205  (FIG. 2A) as outer member  150  slides over and along inner member  105 . Outer member  150  also includes a less-flexible portion  310  distal to flexible portion  305  and a less-flexible portion  315  proximal to flexible portion  305 . For ease of understanding, portions  310  and  315  are referred to as distal portion  310  and proximal portion  315 , indicating their positions relative to flexible portion  305 . FIG. 3B shows a transverse cross-sectional view  320  of portions  310  and  315 . Wall material  325  encloses a circular passage  330 , through which inner member  105  passes. The diameter of passage  330  is sized so that it is not much larger than the diameter of inner member  105 . This allows portions  310  and  315  to slide freely over and along the cylindrical inner member  105 .  
         [0034]    Flexible region  305  accommodates both being flexible enough to conform to curved portion  205  and being strong enough to push distal portion  310  as a surgeon moves trigger  145  (FIG. 1), connected to proximal portion  315  of outer member  150 . As shown in FIGS. 3A and 3C, this is accomplished by removing some of the wall material  325  enclosing passage  330  along flexible portion  305 . In the illustrated example of FIG. 3D, wall material  325  is removed from about a range of 60% to 70% of the circumference (indicated by dashed line  333 ) of passage  330  along flexible portion  305 .  
         [0035]    Referring back to FIGS. 3A and 3C, proximal portion  315  does not extend over the curve of curved portion  205  (FIG. 2) of inner member  105 . Thus, proximal portion  315  does not have to be flexible enough to accommodate and conform to curved portion  205 . Distal portion  310 , however, does extend along and over curved portion  205  of inner member  105 . As described below, distal tip  335  of outer member  150  cuts suture  110 . To accommodate both being able to travel along curved portion  205  and being sufficiently rigid to be able to cut suture  110 , the length of distal portion  310  is relatively small compared to the radius of curved portion  205 . The length of flexible portion  305  is large enough to allow distal portion  310  to accomplish cutting while preventing proximal portion  315  from reaching the curve of curved portion  206 . The distal tip  335  of distal portion  310  includes a cutting surface  340  that pushes against suture  110  during the cutting process. Cutting surface  340  can also include a sharp edge to assist in the cutting process.  
         [0036]    [0036]FIG. 4A illustrates inner member  105  and outer member  150  during the cutting process. To better show suture  110  in channel  225  (FIG. 2D), FIG. 4A represents inner member  105  using a side cross-sectional view (i.e., an extended view of FIG. 2D). During the cutting process, a surgeon moves trigger  145  (FIG. 1) towards the distal end of outer member  150 . Trigger  145  is connected to the proximal portion  315  and causes outer member  150  to move towards the distal end, as indicated by arrow  405 . Distal portion  310  of outer member  150 , being relatively short, moves along and over curved region  205  without having to adapt its form. Flexible portion  305 , however, does bend to adapt and conform to curved portion  205 . As outer member  150  moves along in the direction indicated by arrow  405 , the distal tip  335  of outer member  150  eventually encounters suture  110  that is extending beyond opening  120  of inner member  105 . As distal tip  335  encounters suture  110 , suture  110  becomes pinched between cutting surface  220  of inner member  105  and cutting surface  340  of outer member  150 . As outer member  150  continues to move distally, the cutting surfaces  220  and  340  compress and eventually cut through suture  110 . As described above, sharp edges can be included on either or both cutting surfaces  220  and  340  to assist in this cutting process.  
         [0037]    As shown in FIG. 4A, the wall  325  of flexible portion  305  is disposed on the concave side of curved portion  205 . FIG. 4B shows an example in which flexible portion  305  is disposed on the convex side of curved portion  205 . In some of the examples described above, for clarity, the motion of outer member  150  is described as linear along the concentric axis. In other words, the position of outer member  150  is fixed with respect to rotation about the concentric axis. The motion of outer member  150 , however, is not limited to only linear motion. As shown in FIGS. 4A and 4B, outer member  150  can also rotate about the concentric axis in either direction, as indicated by arrows  410 . As described above, the flexible portion  305  is a flexible transmission mechanism that can translate both linear and rotational forces from an actuating mechanism.  
         [0038]    With rotational transmission as an alternative or in addition to the linear transmission, flexible portion  305  enables a surgeon to use medical instrument  100  for additional procedures beyond the linear cutting described above. For example, a surface  415 ,  420 , and/or a portion thereof of the wall of flexible portion  305  can be a cutting surface during rotational motion in the directions of arrows  410 . Surfaces  415 ,  420 , and/or a portion thereof can also include sharp edges. Suture  110  can be located on the proximal side of distal portion  310 . As outer member  150  is rotated, surface  410  or  415  pinches and cuts any portion of suture  110  extending beyond opening  120 . In addition to cutting suture, a surgeon can use medical device  100  to cut tissue. For example, a surgeon can place opening  120  over a polyp and using rotational and/or linear motion, cut to polyp similar to any of the cutting procedures described above, and remove the polyp from the surgical site. To perform complex procedures, medical instrument  100  can include two or more outer members. Similar to outer member  150 , the additional outer member (not shown) includes a passage, through which inner member  105  and outer member  150  passes, and a flexible member that accommodates and conforms to curved region  205  (FIG. 2A) as the alternative outer member (not shown) slides over and along inner member  105  and outer member  150 . Outer member  150  and the alternative outer member (not shown) can be actuated independently from one another.  
         [0039]    To provide another example, the dimensions and materials for an example medical instrument  100 ′ (not shown) follow. Curved portion  205  is located within 1.00 inch from distal tip  115 . The inside radius of the curve of curved portion  205  is 2.25 inches, with a tolerance of 0.25 inches. Opening  120  is located within 0.41 inches from distal tip  115 . The diameter of channel  225  is 0.024 inches. The diameter of passage  330  of outer member  150  is 0.065 inches. The diameter of outer member  150  is 0.083 inches. The length of distal region  310  is 0.05 inches. The length of flexible portion  305  is 0.95 inches. The inner member  105  is made out of 17-4 PH stainless steel. The outer member  150  is made out of 304 stainless steel.  
         [0040]    A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example only and not to limit other alternatives, the distal tip and channel of the inner member can have different configurations. The diameter of the distal tip and channel can be sized to accommodate two strands of suture, so that the surgeon can pull the suture for both ends of a knot, for example a square knot. Also, although the term suture is used for clarity, the invention is not limited to use with only suture. Any flexible fixating material to effect a repair can be used. Also, the elements of the medical instrument that move can vary. For example, the trigger can move the inner member while the outer member remains stationary. The trigger can also move both the inner member and the outer member simultaneously in opposite directions. Similarly, if more than one outer member is used, the inner member and/or any combination of outer members can be configured to move with one or more actuating mechanisms. Also, although the inner and outer members are described using circular and cylindrical geometries, the invention can also be used with other geometries, such a squares, polygons and the like. Accordingly, other embodiments are within the scope of the following claims.