Abstract:
A method and device for cutting orthopedic cable including tensioning and crimping the cable in a desired position within a surgical cavity. A free end of the cable is inserted a device with two coaxial members having coordinating shearing faces. The shearing faces are moved along the cable to a position proximate a portion of the cable to be cut. Cutting is achieved is by rotating the coaxial members with respect to one another.

Description:
CROSS REFERENCE  
       [0001]     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/523,850 filed Nov. 20, 2003, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND  
       [0002]     The present invention relates to surgical devices and methods and, more particularly, to devices and methods for cutting surgical wire and cable.  
         [0003]     It is a common requirement in orthopedic surgical procedures to anchor two or more elements together, such as pieces of a bone, two or more bones, or a combination of soft tissue and bone. This has been accomplished by a number of devices, such as bone bolts that penetrate two pieces of bone and use a nut to draw the segments together, bone screws and interconnecting plates, wires circling at least two pieces of bone, or sutures into the tissue. Often such devices require a relatively large access opening through surrounding and/or covering tissue to implant the anchoring devices. The enlarged access site may increase patient pain and lengthen recovery time. Further, in some locations it is difficult and impractical to make large access points to reach the appropriate site because of surrounding joints and vessels. Even with devices that penetrate the tissue in a substantially linear manner, i.e. lag bolts, the fracture must often be reduced before drilling and insertion of the bolt. Further, some of these devices may be difficult to use since it may be hard to reduce a fracture between two bone segments and maintain that reduction while the device is inserted. This is particularly true with small bone fragments were the use of threaded implants may tend to rotate one bone segment with respect to another, thereby creating a misalignment between the fragments.  
         [0004]     One approach to solving this problem is the use of cerclage systems that provide an alternative to implants that must penetrate the bone to achieve fixation. These systems rely on passing a cable around two segments of bone and then tensioning the cable to squeeze the bone segments together.  
         [0005]     Another approach to solving the problem of cable fixation is to provide a system of implants and instruments that allow an implant mounted on a flexible tension member to track through a hole drilled across the fracture, providing reduction and fixation of the fracture. The tension member may be implanted through bones as opposed to around them, as in a cerclage system. It may also be possible to use a monofilament wire, rather than a cable as the flexible tension member in the fixation system. In either event, there remains a need for a convenient and effective system for securing two segments of tissue together.  
       SUMMARY  
       [0006]     A method of cutting surgical tension member is disclosed. The method includes tensioning and affixing a locking element on the surgical tension member in a desired position within a surgical cavity, inserting a free end of the surgical tension member into a device with two coaxial members having coordinating shearing faces, moving the shearing faces along the cable to a position proximate a portion of the cable to be cut, and rotating the coaxial members with respect to one another. Another method of a cutting surgical tension member is disclosed. The method includes setting a fractured bone in a desired position utilizing a length of orthopedic wire or cable, and tensioning and crimping the cable or wire next to the bone utilizing a first surgical opening. The method further includes inserting a proximal end of the cable or wire into first and second tubular coaxial members having coordinating, off-center openings on a distal end, moving the distal end of the first and second coaxial members along the cable or wire and into the first surgical cavity to position proximate the crimping, rotating the coaxial members with respect to one another to exert a shear cutting force on the surgical wire or cable, and removing the severed length of cable and the coaxial members from the first surgical opening.  
         [0007]     A device for cutting a surgical tension member is disclosed. The device includes, first and second coaxial members each having an opening in a distal end and an actuatable handle adapted to retain and engage the first and second coaxial members and at a proximal end and to rotate the first coaxial member relative to the second. The openings in the distal ends of the coaxial members function as coordinating shearing faces when the handle is actuated. Another device for cutting a surgical tension member is disclosed. The device includes first and second gripping members pivotally attached to one another, first and second handle grips formed on proximal ends of the first and second gripping members, respectively, an outer tubular member attached on a proximal end to a distal end of the first gripping member substantially orthogonal to the first gripping member, an inner tubular member within the outer tubular member and having at least one pin radially attached on a circumference of a proximal end, and a movable barrel interposing the first and second tubular members along a length of a portion of the proximal ends of each and having at least one helical groove configured to engage the at least one pin of the inner tubular member. A distal end of the second gripping member is attached to a proximal end of the movable barrel and the distal ends of the outer tubular member and inner tubular member have openings that are off-center but substantially aligned such as allow a surgical cable or wire to pass through and to exert a shearing force on the cable or wire when the inner tubular member rotates with respect to the outer tubular member as a result of drawing together the first and second handle grips, the correspondent movement of the moveable barrel, and the interaction of the at least one helical groove with the at least one pin.  
         [0008]     A surgical device for translating grip force to cutting force is disclosed. The device includes an inner cylinder disposed coaxially within an outer cylinder, a movable barrel interposing the inner and outer cylinders along a portion of a length of the cylinders and proximate a first end of the cylinders, and a squeezable grip secured to the outer cylinder and adapted to actuate the movable barrel lengthwise between the cylinders when the grip is squeezed. The movable barrel has one or more helical tracks configured to interact with one or more pins attached to the inner cylinder.  
         [0009]     The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the detailed description that follows. Additional features will be described below that may further form the subject of the claims herein. Those skilled in the art should appreciate that they can readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a perspective view of one embodiment of a device for cutting a surgical tension member.  
         [0011]      FIG. 2  is an exploded view of the device of  FIG. 1 .  
         [0012]      FIG. 3A  is a partial cross-sectional view of the device of  FIG. 1  taken along the longitudinal axis.  
         [0013]      FIG. 3B  is a partial end view of the device in  FIG. 1 .  
         [0014]      FIG. 4A  is another partial cross-sectional view of the device in the cutting position.  
         [0015]      FIG. 4B  is another end view similar to  FIG. 3B , showing the cutting position.  
         [0016]      FIGS. 5-6  illustrate incomplete cuts in surgical cable.  
         [0017]      FIG. 7  illustrates a complete cut at a distance from a surgical site.  
         [0018]      FIGS. 8-9  illustrate exemplary cuts made by the device of  FIGS. 1-4 .  
         [0019]      FIG. 10A  illustrates one possible surgical procedure utilizing aspects of the present disclosure.  
         [0020]      FIG. 10B  shows one step in the surgical procedure of  FIG. 10A  utilizing the device of  FIGS. 1-4 . 
     
    
     DETAILED DESCRIPTION  
       [0021]     It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.  
         [0022]     Referring to  FIG. 1 , a perspective view of one embodiment of a device  100  for cutting surgical wire or cable is shown. A movable handle  400  with a slot  401  and a stationary handle  102  are pivotally connected by a lock  600 . An outer nose  101  is provided along with a nose retaining element  500  with knurled surface  501 . A spring  900  provides an opening bias between the movable handle  400  and the stationary handle  102 .  
         [0023]     The stationary handle  102  may be made from surgical grade stainless steel, plastic, polymers, or other suitable materials or combinations thereof. The stationary handle  102  may be formed by casting, machining, polishing, and/or other methods or combinations thereof. The exact dimensions of the stationary handle  102  may vary with the application, but the size will generally be such that an operator may maintain a comfortable and effective grip on the device  100  during operation, which is described in greater detail below.  
         [0024]     The movable handle  400  may be made from similar or different materials than the stationary handle  102 , including surgical grade stainless steel, plastic, polymers, or other suitable materials or combinations thereof. The movable handle  400  may be formed by casting, machining, polishing, and/or other methods or combinations thereof. The dimensions of the movable handle  400  may be chosen to match those of the stationary handle  102 , and may be chosen such as to provide an effective and comfortable grip for the operator. As will be described in greater detail below, the moveable handle  400  may be equipped with a slot  401  adapted to engage a moveable inner barrel (not shown in  FIG. 1 ).  
         [0025]     The stationary handle  102  and the moveable handle  400  are pivotally connected by lock  600 . The lock  600  allows the stationary handle  102  and the moveable handle  400  to move in the same plane of motion in a scissor-like fashion. As will be shown in greater detail below, the lock  600  may be a metal screw or rivet. The lock  600  may comprise the same or different materials than the stationary handle  102  and the moveable handle  400 . For example, the lock  600  may be surgical grade stainless steel or another suitable material.  
         [0026]     The spring  900  interposes the stationary handle  102  and the moveable handle  400 . The spring may be attached to the interior facing surfaces of the handles  102 ,  400  at a suitable location between the lock  600  and the ends of the handles  102 ,  400  distal from the lock  600 . The spring  900  may be permanently or removably attached to the handles  102 ,  400 . The spring  900  may be glued, screwed, or riveted in place. The spring may comprise spring steel, another type of steel, plastic, other suitable materials, and/or combinations thereof. In  FIG. 1 , the spring  900  is shown as two pieces in a leaf spring configuration. In other embodiments, the spring  900  may be a single piece, or may be a coil spring or other suitable implement. The spring  900  may serve to keep the device  100  in an open position when not in use. The spring  900  may also be suitably strong to force the handles  102 ,  400  open during use when the operator is not applying pressure to allow for easy one-handed operation of the device  100 .  
         [0027]     The outer nose  101  may be formed integrally with stationary handle  102 , or they may be formed separately and then attached together, by welding or gluing, for example. The outer nose  101  may be formed of similar or different materials than the other components of the device  100 . The outer nose  101  may be composed of surgical grade stainless steel, for example. The outer nose  101  may be formed by casting, machining, and/or other methods. As will be described in greater detail below, the outer nose  101  may be substantially hollow to accommodate an inner cylinder (not shown in  FIG. 1 ).  
         [0028]     A retaining element  500  with a knurled surface  501  may also be attached to the outer nose and/or stationary handle  102 . The retaining element  500  may be composed of different or similar materials than the other components of the device  100 . The retaining element may comprise surgical grade stainless steel, another metal, plastic, polymers, other suitable materials, and/or combinations thereof. The retaining element  500  may be formed by machining or casting, for example. The knurled surface may be engraved or machined into the retaining element  500 .  
         [0029]     Referring to  FIG. 2 , with continued reference to  FIG. 1 , an exploded view of one embodiment of a device  100  for cutting a surgical tension member is shown. Here it may be seen that the stationary handle  102  attaches to the moveable handle  400  pivotally by the lock  600 . The lock  600  is shown here as being held in place by screws  700  and  800 . The moveable handle  400  may also be seen here to have a cam surface  402  and slot  401 . Also, as described previously, the spring  900 , shown here as two pieces, may attach to the stationary handle  102  and moveable handle  400  by screws.  
         [0030]     The slot  401  of the moveable handle  400  may be configured to engage a pin  302  near a first end of a movable barrel  300 . The moveable barrel may be made from similar or different materials that the components previously described. In one embodiment, the barrel  300  comprises surgical grade stainless steel. The barrel  300  may be formed by casting, machining, and/or other methods. The movable barrel  300  may also have tracks or slots  301  cut or cast into it that interact with pins  203  as described below. In one embodiment, the slots  301  are arranged in a helical pattern about the walls of the barrel  300 .  
         [0031]     A cutter insert  200  may be coaxially fitted into the substantially hollow outer nose  101 . In addition to pins  203 , the insert  200  may also have a retaining groove  202  and a cylinder  201  with a cutting face  204  and an opening  205 . The insert  200  may be hollow to allow a surgical cable to pass through to opening  205 . In another embodiment, a channel may be cut lengthwise into the insert  200 , which may allow a cable to pass through when the insert is inside the outer nose  101 . The insert may be made from the same or different materials than the components previously described. The insert  200  may be made from surgical grade stainless steel, for example. The insert may be formed by casting, machining, or other methods. The cutting face  204  and opening  205  as well at the pins  203  may be formed integrally with the insert  200 , or attached as separate components. The retaining groove  202  may be cut into the insert  200  and may be configured to engage a threaded pin  502 . The threaded pin  502  may be a part of the retaining element  500  and may serve to anchor the retaining element  500  into the stationary handle  102  and retain the insert  200  in place when the device  100  is assembled. Similarly, when the device  100  is assembled, the slot  401  may engage the pin  302  to enable actuation of the device  100  as described below.  
         [0032]     Referring to  FIG. 3A , with continued reference to  FIGS. 1 and 2 , a sectional view of one embodiment of a device  100  for cutting surgical wire or cable is shown. In  FIG. 3A , the device is shown fully assembled. Here it can be seen that openings  105  and  205  align to pass a surgical tension member, such as a cable or wire. The openings are shown as circular but the device is not so limited and other shapes for the openings may be utilized. The cable or wire (not shown) may pass through the channel or hollow portion of the insert  200  and out the back of the device  100 . The dimensions of the insert  200  and the outer nose  101  may be chosen such that when assembled, the cutting face  204  is substantially flush against the inside cutting surface  104  of the outer nose  101 . To retain this position, the threaded pin  502  may be seen inserted into the non movable handle  102  and engaging retaining groove  202 . The moveable barrel  300  may be seen engaged with pins  203  via the helical cutouts  301  and engaged with the movable handle  400  via the pin  402  and slot  401 .  FIG. 3A  illustrates the device  100  in an “open” state to allow a wire or surgical cable to pass.  
         [0033]     Another open view of the device  100  may be seen in  FIG. 3A  which is taken along the line  3 B of  FIG. 3A . The outer nose  101  may be seen in relation to the insert  200  (shown in broken line). Similarly, the alignment of the openings or holes  105  and  205  corresponding to the outer nose  101  and insert  200 , respectively may also be seen.  
         [0034]     Referring to  FIG. 4A , with continued reference to  FIGS. 1-3 , another sectional view of one embodiment of a device  100  for cutting surgical tension members is shown. Surgical tension members may include any of a variety of materials and configurations. For example the tension member may be flexible, except in the longitudinal direction, and have sufficient rigidity to hold tension such that compressive force is transmitted to adjacent tissues to resist longitudinal movement. Without limitation, examples of surgical tension members may include; cable, wire, filaments, braided strands, elongated composites, rods or other structures formed of biocompatible materials suitable for implantation.  
         [0035]      FIG. 4A  depicts the device  100  in a “closed” position. The moveable handle  400  has been drawn in toward the stationary handle  102 , and the spring  900  is compressed. The movement of the movable handle  400  pivotally about the lock  600  may cause the movable handle  400  to come to rest against screw  402  when the device  100  is fully closed. Further, the slot  401  engaged with the pin  302  causes the movable barrel  300  to move along the direction of the outer nose  101 . The helical slots  301  cause a rotation of the pins  203  and therefore the insert  200 . The insert  200  is free to rotate in place but is prevented from moving along its axis by threaded pin  502  and retaining groove  202 .  
         [0036]     Referring now to  FIG. 4B , a another view of  FIG. 4A  taken along the line  4 B is shown. With the rotation of the insert  200  (shown in broken line) relative to the outer nose  101 , the alignment of the holes  205  (shown in broken line) and  105  is also changed. Because the face  204  of the insert is flush with the interior  104  of the outer nose  101 , a shearing force may cause the cable or wire inserted through the holes  105 ,  205  to be cut. In this way a cut in a wire or cable may be made from a direction substantially coaxial to the wire or cable. In one embodiment, the alignment of the holes  105  and  205  will become offset by about 110°, which may substantially equal the degree of rotation of the movable barrel  300 . In one embodiment, this is approximately 10° beyond the intersection of the openings of the holes  105 ,  205 . This 10° of additional travel may ensure complete cutting of the cable. Further, in one embodiment shown in  FIG. 3A , the thickness between the distal surface of outer nose  101  and interior surface  104  approximates how close the cable may be sheared next to the locking element.  
         [0037]     Referring now to  FIGS. 5-6 , incomplete cuts in surgical cables are shown. These may result, for example, from cutting of the cable with a traditional cutter at less than an optimal angle (e.g., within a surgical cavity).  FIG. 7  illustrates a complete cut at a distance from a surgical site, which may also result, for example, due to difficulties with placing traditional cutting device in an optimal position within the surgical cavity.  FIGS. 8-9  illustrate exemplary cuts, which may be made by the device  100  of  FIGS. 1-4 , even within a surgical cavity.  
         [0038]     Referring to  FIG. 10A , with continued reference to  FIGS. 1-9 , one possible surgical procedure utilizing aspects of the present disclosure is illustrated. A surgical site is shown here in which a cable or wire has been used to close a fracture. Referring to  FIG. 10B , with continued reference  FIGS. 1-10A , the device  100  is shown in operation. After the cable or wire implant has been inserted, it may be tensioned and affixed to a locking element such as the crimps shown in  FIGS. 5-9 . Following crimping, it may be necessary to trim off the excess cable that was required for anatomical reduction and instrumentation. The device of  FIGS. 1-4  may be utilized to provide a reproducible cut as close to the surgical crimp as possible. The device may be inserted into the same incision as was used to access the surgical site and for the crimping and tensioning. The device may be passed over the length of cable, advanced through the soft tissue incision, down to the site of the crimp until the instrument stops upon contact with the crimp. In one aspect the outer nose has a length sufficient to position the handles outside the patient. Slight tension may be applied to the cable extending from the back of the device to ensure that the cutter is fully seated against the surgical crimp. With the opposite hand, the handles of the device may be actuated (while still maintaining slight tension on the free cable). Once the cable has been successfully cut, the free cable abruptly releases from the surgical site and the cut cable is discarded. The operator may wish to take one ore more radiographs at varying perspectives to ensure that tension has not been lost and reduction and fixation of the fracture was successful.  
         [0039]     Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. For example, various steps of the described methods and sequences may be executed in a different order or executed sequentially, combined, further divided, replaced with alternate steps, or removed entirely. In addition, various functions illustrated in the methods or described elsewhere in the disclosure may be combined to provide additional and/or alternate functions. Those skilled in the art should also realize that such equivalent constructions 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.  
         [0040]     The present inventions may find application in many medical procedures. For example, but without limitation, such surgical procedures can include those disclosed in U.S. Pat. Nos. 6,019,762 and 6,068,648 to Cole et al., incorporated herein by reference in their entirety.