Abstract:
An elongate member having a fixed end is passed through a plurality of grippers that impart tension in the elongate member and prevent the tension from being released. At least one gripper is movable while at least one other can be fixed. The movable gripper travels along the elongate member toward the fixed end then reverses direction, grips the elongate member, and carries the elongate member away from the fixed end, thereby creating tension in the elongate member. At least one gripper prevents the tension from being released. In some embodiments, the elongate member passes through a rotatable shaft with a lumen. The shaft can be in communication with a crank, whereby operation of the crank rotates the shaft.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    Embodiments of the present invention relate to tensioning a flexible elongate member, such as a wire, cable, or tether. Some embodiments relate to the use of an elongate member in surgical applications, such as use in a segmented intramedullary or IM nail, which is used in the treatment of long bone fractures. 
         [0003]    2. Description of the Related Art 
         [0004]    The use of elongate members is well known in the art. Elongate members are used to conduct electrical current, support bridges and buildings, and carry data worldwide virtually instantaneously. An elongate member can be any flexible elongated member capable of maintaining tension up to its yield strength, such as but not limited to, wire, cable, tether, rod, threaded rod, rope, line, chain, twine, yarn, and string. An elongate member can be a variety of materials, such as but not limited to, copper, steel, iron, tin, silver, gold, cotton, hemp, sisal, nylon, aramids, polyester, and polypropylene. Depending on the application, an elongate member can be monofilament or multifilament, stranded or unstranded, coated or uncoated, sheathed or unsheathed. 
         [0005]    Elongate members are generally tensioned in order to carry a load. Conventional elongate member tensioners typically employ a ratchet mechanism to impart the tensile force on the elongate member and prevent the elongate member from slipping as the tension increases. For instance, U.S. Pat. No. 2,980,974 (Santis), discloses an elongate member tensioner with a ratcheting mechanism. However, by the nature of the ratchet, such tensioners have adjustment that is limited to the spacing of the ratchet teeth. Thus, such tensioners generally cannot maintain levels of tension that do not correspond with the location of the ratchet teeth. 
         [0006]    The elongate member is normally secured after it is tensioned. This is usually achieved using a crimp, clamp, or compression device. Typically, such securing devices require the use of unique tools, such as special pliers, which are separate from the tensioning device. Thus, a person installing the elongate member can be required to provide, maintain, and manipulate separate devices to tension and lock the elongate member. 
         [0007]    A surgical elongate member is a special type of elongate member that is used in a variety of medical procedures, such as fracture fixation, total hip arthroplasty, and other trauma surgery. A surgical elongate member is typically a slender length of surgical elongate member manufactured from a biocompatible material, such as but not limited to, titanium, stainless steel, or tungsten. Surgical elongate member can be used to provide stability and support to a fractured or otherwise injured area, or to affix other objects to the bone. Often, the surgical elongate member must be tensioned to secure it and provide adequate stability and support. If the tension in the surgical elongate member is too slight, the surgical elongate member can shift from the injured area and fail to provide the stability and support desired. On the other hand, if the surgical elongate member is too highly tensioned, it can cause injury to the patient&#39;s body or other implanted devices. 
         [0008]    Like other types of tensioners discussed above, surgical elongate member tensioners often employ a ratchet. For instance, U.S. Pat. No. 5,312,410 (Miller et al.) discloses an elongate member tensioner with a ratcheting mechanism. As stated, such mechanisms have adjustment limited to the ratchet tooth spacing. 
       SUMMARY 
       [0009]    A tensioning device that provides continuous and uninterrupted adjustment could provide improved control of tension imparted to an elongate member. Additionally, a tensioning device with the ability to secure an elongate member would remove the need for separate tools, enhance safety, and simplify the installation process. To those ends, the disclosed inventions generally seek to provide full tension control of an elongate member and the independent ability to secure an elongate member under tension. 
         [0010]    In accordance with some embodiments disclosed herein, a tensioning device and method for tensioning are provided. The device can comprise a body with proximal and distal ends. Some embodiments include a handle to facilitate handling and control of the device. In some embodiments, the device and method may be for compressing a device or bone by tensioning an element connected to the device or bone. In various non-limiting embodiments, the device can be called a tensioner, a compressor, a gun, a tensioner gun instrument, a cable gun tensioner, or other names. In one embodiment the cable gun tensioner instrument consists of two unique and independent mechanisms. The first mechanism is a dual piston mechanism that can be cycled by pulling the trigger of the tensioner. The first piston cycles back and forth thereby pulling the cable through the tensioner while the second piston serves to hold the tension applied to the cable by the first piston. The entire two piston mechanism abuts a spring that is intended to indicate the tension being applied to the cable. 
         [0011]    Some embodiments comprise a plurality of grippers. In one embodiment, the grippers are aligned to permit an elongate member with proximate and distal ends to pass unimpeded in one direction. In other embodiments, the grippers are not aligned. In one embodiment, the grippers permit the elongate member to freely move in the proximate direction, but prevent the elongate member from moving in the distal direction. Thus, when the distal end of the elongate member is fixed, the grippers can impart tension to the elongate member and prevent such tension from being released. 
         [0012]    In some embodiments, the grippers work in conjunction. One or more grippers can traverse a length of the elongate member and one or more grippers can be fixed. Upon reaching a desired length of travel in the distal direction, the movable gripper reverses course and begins moving proximally. In doing so, the movable gripper locks onto the elongate member, thereby carrying the elongate member proximally and increasing the tension in the elongate member. Upon reaching a desired proximal length of travel, the movable gripper begins travelling distally again and releases its hold on the elongate member. When the movable gripper releases, the fixed gripper locks the elongate member, thus preventing the elongate member from moving in the distal direction and the tension from being released. Some embodiments can have a mechanism to release the movable gripper&#39;s grip on the elongate member. Various embodiments are configured to measure the amount of tension in the elongate member. For instance, one embodiment comprises a spring coupled to an indicator to reflect the amount of tension in the elongate member. 
         [0013]    Certain embodiments employ a trigger connected to one or more of the grippers by a linkage. In one embodiment, the linkage is designed such that when the trigger is moved proximally, the movable gripper also moves distally. In another embodiment, moving the trigger proximally moves the gripper proximally. Other embodiments have alternate linkage configurations. 
         [0014]    Embodiments of the device can also comprise a rotatable shaft with a lumen. Various embodiments align the plurality of grippers so that the elongate member can simultaneously pass through the grippers and the lumen. However, this is not required. In some embodiments, the lumen is configured to interface a compressible implant, thereby locking the elongate member in place. In some embodiments, the shaft can be controlled by a crank. In one embodiment, the crank is located at the proximal end of the tensioner and the shaft at the distal end of the tensioner. In some embodiments sets of gears connect the crank to the shaft via an offset rod. 
         [0015]    Other embodiments include a method of imparting tension to an elongate member using the plurality of grippers discussed above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    These and other features, embodiments, and advantages of the present invention will now be described in connection with preferred embodiments of the invention, in reference to the accompanying drawings. The illustrated embodiments, however, are merely examples and are not intended to limit the invention. 
           [0017]      FIG. 1  is a perspective view of a tensioner, according to a first embodiment of the disclosure. 
           [0018]      FIG. 2  is a perspective sectional view of the tensioner shown in  FIG. 1 . 
           [0019]      FIG. 3  is a plan sectional view of the tensioner shown in  FIG. 1 . 
           [0020]      FIG. 4  is a partial plan sectional view of the tensioner shown in  FIG. 1  in the extended position. 
           [0021]      FIG. 5  is a partial plan sectional view of the tensioner shown in  FIG. 1  in the retracted position. 
           [0022]      FIG. 6  and  FIGS. 6A-6D  are a schematic chart of an embodiment of a method for imparting tension in an elongate member using a plurality of grippers. 
       
    
    
       [0023]    Throughout the figures, the same reference numerals and characters, unless otherwise stated, are used to denote like features, elements, components or portions of the illustrated embodiments. In certain instances, similar names can be used to describe similar components with different reference numerals which have certain common or similar features. In various embodiments, multiples of the same embodiment, or different embodiments of a designated reference number can be used with a prime (′) symbol on the reference number. For example, if a first part with reference number 000 is designated, multiples of the same or a different embodiment of that reference can include a second 000′, third 000″, etc. Moreover, while embodiments of the subject invention will now be described in detail with reference to the figures, it is done so in connection with the illustrative embodiments. It is intended that changes and modifications can be made to the described embodiments without departing from the true scope and spirit of the subject invention as defined by the appended claims. 
       DETAILED DESCRIPTION 
       [0024]    In accordance with the present disclosure, various embodiments of a device and method for tensioning an elongate member are provided. An elongate member can be any flexible elongated member capable of maintaining tension up to its yield strength, such as but is not limited to, wire, cable, tether, rod, threaded rod, rope, line, chain, twine, yarn, and string. An elongate member can be a variety of materials, such as but not limited to, copper, steel, iron, tin, silver, gold, cotton, hemp, sisal, nylon, aramids, polyester, and polypropylene. Depending on the application, an elongate member can be monofilament or multifilament, stranded or unstranded, coated or uncoated, sheathed or unsheathed. Use of terms related to embodiments of elongate members can be used interchangeably and should be understood to refer to the various types of embodiments of the elongate member being used. For example, cable can be used to describe any number of types of elongate members, but should not be necessarily limited to use only with a cable. 
         [0025]      FIG. 1  shows a first embodiment of a tensioning device  10 . The illustrated embodiment of the tensioning device  10  comprises a body  12  having a proximal end  14  with a rotatable crank  40 , and a distal end  16  with a rotatable shaft  42 . The illustrated embodiment of the device  10  has a length of about 320 mm. Various embodiments have other lengths, such as about 100 mm to about 600 mm, about 200 mm to about 500 mm, and about 300 mm to about 400 mm. However, other lengths of the device  10  can be used. 
         [0026]    In one embodiment the device  10  can have one or more protective covers  18  connected to the body  12 . Embodiments can include a handle  20  interfacing the body  12  or the protective cover or covers  18 . The body  12 , protective cover or covers  18 , and handle  20  can each be metal, plastic, fiberglass, hard rubber, resin, or similar material. 
         [0027]    As shown in one embodiment in  FIG. 2 , the body  12  houses a plurality of grippers  22 . The grippers  22  are configured to permit an elongate member  24  to freely move proximally, but not distally. Thus, when the elongate member  24  is distally fixed, the grippers  22  can proximally move the elongate member  24  to impart tension and prevent such tension from being released. In the illustrated embodiment, the grippers  22  are aligned to permit the elongate member  24  to concurrently pass through both grippers  22 . In other embodiments, the grippers  22  are not so aligned. 
         [0028]    In the illustrated embodiment, the grippers  22  provided are according to U.S. Patent Application No. US 2007/0171540 (Veldman et al.), the disclosure of which is hereby incorporated by reference. In sum, each of the grippers  22  includes one or more spheres held within a hollow conical chamber that tapers from a larger cross section proximally to a smaller cross section distally. The elongate member  24  enters the conical chamber distally, passes between the spheres, and continues out through an axial opening in the proximal end of the chamber. Proximal movement of the elongate member  24  can be freely accomplished, since the spheres tend to advance into the larger diameter of the chamber. Conversely, distal movement of the elongate member  24  tends to draw the spheres into the smaller diameter of the chamber. The tapered walls of the chamber wedge the spheres inwardly against the elongate member, thus preventing distal movement. 
         [0029]    It should be noted that other embodiments of the device  10  can employ alternate designs and/or configurations of the grippers  22 , such as, but without limitation, wedges, clamps, clasps, springs, fasteners, ratchets, magnets, threads, and the like. 
         [0030]    The illustrated embodiment includes a first gripper  26  and a second gripper  28 . In some embodiments, in relation to the device body  12 , the first gripper  26  remains substantially fixed, while the second gripper  28  travels proximally and distally. In other embodiments, in relation to the device body  12 , the first gripper  26  travels proximally and distally and the second gripper  28  remains substantially fixed. In still other embodiments, both grippers  22  can travel proximally and distally. Yet further embodiments include both grippers  22  that are substantially fixed. 
         [0031]    In the embodiment shown, the proximal length of travel of the second gripper  28  can be about 3 cm-30 cm. However, other embodiments can have different lengths of travel. For example, an alternate embodiment has a second gripper  28  that travels about 5 cm-20 cm. Another embodiment includes a first gripper that travels about 1 cm-20 cm. Other lengths of travel are possible. 
         [0032]    Note that, from the perspective of the grippers  22 , proximal movement of the grippers  22  along the elongate member  24  is equivalent to distal movement of the elongate member  24  along the grippers  22 . Thus, the grippers  22  will lock to the elongate member  24  when either the elongate member  24  moves distally to the grippers, or the grippers  22  move proximally to the elongate member  24 . 
         [0033]    Accordingly, when an elongate member  24  is passed through the grippers  22 , the second gripper  28  can freely distally traverse a length of the elongate member  24 . But when the second gripper  28  travels proximally, the second gripper  28  locks to the elongate member  24 . Thus, the second gripper  28  can proximally carry the elongate member  24 , thereby increasing the tension in the elongate member  24 . During the distal movement of the second gripper  28 , tension in the elongate member tends to lock the first gripper  26  to the elongate member  24 , thereby impeding the elongate member  24  from moving distally. 
         [0034]    Depending on the application, alternate embodiments of the device  10  can produce various amounts of tension in the elongate  24 . For example, but without limitation, the embodiment shown is configured to impart a tension of up to about 100-1,000 pounds into the elongate member  24 . However, other embodiments of the device  10  are designed to impart other amounts of tension. 
         [0035]    Turning to  FIG. 3 , some embodiments includes a release mechanism  30  to release the lock of grippers  22  on the elongate member  24 . In the illustrated embodiment, the release mechanism  30  is comprised of a release knob  31  connected to a release linkage  33 , which is coupled to the second gripper  28 . Proximal movement of the release knob  31  interfaces features on the body of the grippers  22 , thereby proximally moving the grippers  22  and thus releasing the lock of the grippers  22  on the elongate member  24 . Other embodiments use other release mechanism  30  configurations. Some embodiments include a safety feature, such as a detent, to prevent inadvertent operation of the release mechanism  30 . 
         [0036]    The illustrated embodiment includes a trigger  36  connected to the grippers  22  by a linkage  38 . In other embodiments, the trigger  36  is connected to only one of the first gripper  26  or second gripper  28 . As shown, the trigger  36  is manually actuated by the hand of the device  10  user. Various other embodiments include a trigger  36  with actuation assistance, such as electrical, hydraulic, pneumatic, or similar actuation. 
         [0037]    The linkage  38  can be configured for various manners of operation. For instance, in one embodiment, when the trigger  36  is moved proximally the second gripper  28  is moved distally. In another embodiment, moving the trigger  36  proximally moves the second gripper  28  proximally. Various other embodiments have alternate linkage  38  configurations. 
         [0038]    The illustrated embodiment includes a spring  32  and indicator  34  (not shown) for measuring the amount of tension in the elongate member  24 . The spring  32  can be, without limitation, a coil spring, wave spring, belleville washer, wave washer, leaf spring, torsion bar, gas spring, or the like. Some embodiments incorporate a sensor that outputs a signal in relation to the force on the spring  32  or in relation to the tension in the elongate  24  directly. The indicator  34  can be, but is not limited to, a mechanical, pneumatic, or electrical gage or the like. The indicator  34  can also be a visual or aural signal configured to activate at a determined level of tension. 
         [0039]    As shown, when the second gripper  28  locks to the elongate member  24 , the tension of the elongate member  24  is transferred through the second gripper  28  to the spring  32 , thereby putting the second gripper  28  in communication with the spring  32  and compressing the same. The spring  32  is connected to the indicator  34 , which can be calibrated to measure the amount of force on the spring  32  and thereby register the amount of tension in the elongate member  24 . It is to be understood that this is merely one approach for assessing and indicating the force on the elongate member  24 , and that other embodiments employing various other measurement and indication means are contemplated. 
         [0040]    With continued reference to  FIG. 3 , the illustrated embodiment of the tensioning device  10  has a rotatable crank  40  at the proximal end  14  and a rotatable shaft  42  at the distal end  16 . The crank  40  is in communication with a first set of gears  44 , while the shaft  42  is in communication with a second set of gears  48 . Both the first set of gears  44  and second set of gears  48  are in communication with an offset rod  46 . Thus, rotating the crank  40  transmits the rotational movement to the shaft  42  via the first set of gears  44 , the offset rod  46 , and the second set of gears  48 . The configuration of the sets of gears  44 ,  48  can be, but is not limited to, spur, helical, beveled, worm, rack and pinion, friction, belt-drive, or the like. The material of the sets of gears  44 ,  48  can be metal, plastic, or the like. 
         [0041]    Alternate embodiments include other approaches for rotating the shaft  42 . One embodiment includes a signaling device, such as a button, toggle, or similar, in electronic communication with a motor in rotatable communication with the shaft  42 , such that operation of the signaling device initiates the motor to rotate the shaft  42 . In another embodiment, the crank is located at the distal end  14  of the device  10  and is in communication with the shaft  42  via gears or the like. Still further embodiments include handles, knobs, grips, or texture features on the shaft  42  to facilitate its rotation. 
         [0042]    In the embodiment shown, the rotatable shaft  42  includes a lumen  50  and is connected to the distal end of the body  12  of the tensioning device  10 . The shaft  42  can be made from a biocompatible material, such as titanium, stainless steel, or other materials. As shown, the shaft  42  and grippers  22  are aligned so that the elongate member  24  can simultaneously pass through the grippers  22  and the lumen  50 . However, this is not required. In one embodiment, the lumen  50  is configured to interface a compressible implant  52  (not shown), for securing the elongate member  24  under tension. For example, in one embodiment the lumen  50  is configured to interface a threaded collet as disclosed in U.S. Pat. No. 7,172,595 (Goble). Other embodiments include alternate configurations of the lumen  50 . 
         [0043]    In the illustrated embodiment, the movement of the trigger  36 , grippers  22 , spring  32 , and indicator  34  are independent of the movement of the crank  40 , sets of gears  44 ,  48 , offset rod  46 , shaft  42 , and lumen  50 . Accordingly, the ability to tension the elongate member  24  is independent of the ability to secure the elongate member  24 . In other embodiments, these abilities can be interrelated, such as by a linkage, belt, spring, cam, gearing, or similar. 
         [0044]      FIGS. 4 and 5  illustrate the internal operation of one embodiment of the device  10 . In  FIG. 4 , the device  10  is shown in the extended state, in which the trigger  36  is a distance apart from the handle  20  and the linkage  38  is distally disposed. As the trigger  36  is retracted toward the handle  20 , the linkage  38  moves proximally. This retracted state is illustrated in  FIG. 5 . Due to the configuration of the linkage  38  and its connection to the grippers  22 , the proximal travel of the linkage  38  distally encourages the grippers  22 . When the trigger  36  is allowed to return to its initial extended position, the grippers  22  also return to their initial position, thereby allowing the trigger  36  to be retracted again. Note that  FIGS. 4 and 5  are only one embodiment and that other configurations are contemplated. 
         [0045]      FIG. 6  is a schematic chart illustrating an embodiment of a method for tensioning an elongate member using a plurality of grippers. In the illustrated embodiment, a plurality of grippers  116  are provided along with an elongate member  110  with a fixed distal end  112  and a free proximal end  114 . The grippers  116  are designed as to allow proximal movement of the elongate member  110  and prevent distal movement of the elongate member  110  by locking to it. The grippers  116  are arranged to receive the elongate member  110 , and the proximal end  112  of the elongate member  110  is passed through the grippers  116 . As shown in  FIG. 6A , the second gripper  118  can be moved proximally. From the perspective of the second gripper  118 , proximally moving the second gripper  118  along the elongate member  110  is equivalent to distally moving the elongate member along the second gripper  118 . Accordingly, the second gripper  118  can lock to the elongate member  110  and carry the elongate member  110  through the duration of the second gripper&#39;s  118  proximal movement. Because the distal end  116  of the elongate member  110  is fixed, the proximal movement of the elongate member  110  with the second gripper  118  encourages tension in the elongate member  110 . As shown in  6 B, upon reaching the conclusion of its proximate travel, the second gripper  118  can move distally along the elongate member  110 , thereby releasing its grip on the elongate member  110 . Although the tension in the elongate member  110  would tend to shift the elongate member  110  distally, the first gripper  20  remains substantially fixed and locks to the elongate member  110 , thereby preventing distal movement and maintaining the tension. As shown in  FIGS. 6C and 6D , the above-described steps may be repeated. 
         [0046]    Thus, an improved tensioning device and method have been provided as described above. While the structure has been described in terms of certain specific embodiments, there is no intention to limit the invention to the same. It will be understood that the foregoing is only illustrative of the principles of the invention, and that various modifications, alterations, and combinations can be made by those skilled in the art without departing from the scope and spirit of the invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims.