Abstract:
Various exemplary embodiments relate to a distractor system including one or more of the following: a distraction screw comprising a double threaded distal portion and a nonthreaded locking feature near a proximal end of the distraction screw; a crossbar; a first arm coupled to the crossbar; a second arm coupled to the crossbar and having an interior bore sized to receive at least a portion of the distraction screw; and a lock having a nonthreaded aperture sized to receive at least a portion of the distraction screw therethrough, wherein the lock is configurable in a first position and a second position, when configured in the first position the lock engages the locking feature to substantially inhibit axial movement of the distraction screw within the interior bore, and when configured in the second position the lock substantially permits axial movement of the distraction screw within the interior bore.

Description:
TECHNICAL FIELD 
     Various exemplary embodiments disclosed herein relate generally to surgical devices. 
     BACKGROUND 
     Various surgical procedures involve the distraction of bones away from one another. For example, a spinal discectomy may require that the vertebrae adjacent the disc to be removed be temporarily separated. This separation may enable removal of the disc and subsequent introduction of an intervertebral implant. To effect such distraction, a surgeon may employ the use of a distraction device, specifically adapted to move bones away from one another. 
     SUMMARY 
     A brief summary of various exemplary embodiments is presented below. Some simplifications and omissions may be made in the following summary, which is intended to highlight and introduce some aspects of the various exemplary embodiments, but not to limit the scope of the invention. Detailed descriptions of a preferred exemplary embodiment adequate to allow those of ordinary skill in the art to make and use the inventive concepts will follow in later sections. 
     Various exemplary embodiments relate to a distractor system including: a distraction screw including a double threaded distal portion and a nonthreaded locking feature near a proximal end of the distraction screw; a crossbar; a first arm coupled to the crossbar; a second arm coupled to the crossbar and having an interior bore sized to receive at least a portion of the distraction screw; and a lock having a nonthreaded aperture sized to receive at least a portion of the distraction screw therethrough, wherein the lock is configurable in a first position and a second position, when configured in the first position the lock engages the locking feature to substantially inhibit axial movement of the distraction screw within the interior bore, and when configured in the second position the lock substantially permits axial movement of the distraction screw within the interior bore. 
     Various exemplary embodiments relate to a distractor system including: an arm having an interior bore sized to receive at least a portion of a distraction screw; and a lock having a nonthreaded aperture sized to receive at least a portion of the distraction screw therethrough, wherein the lock is configurable in a first position and a second position, when configured in the first position the lock substantially inhibits axial movement of the distraction screw within the interior bore, and when configured in the second position the lock substantially permits axial movement of the distraction screw within the interior bore. 
     Various exemplary embodiments relate to a distractor system including: a distraction screw including: a distal portion configured to be driven into bone, wherein the distal portion includes a first thread and a second thread that is at least partially intertwined with the first thread, a nonthreaded locking feature near a proximal end of the distraction screw, wherein the nonthreaded locking feature is configured to be engaged by a lock attached to a distractor arm. 
     Various embodiments are described wherein the second arm includes a proximal arm portion and a distal arm portion movable with respect to the proximal arm portion. 
     Various embodiments are described wherein the lock is biased into the first position. 
     Various embodiments are described wherein the lock includes a spring that biases the lock into the first position. 
     Various embodiments are described wherein: the second arm further includes a slot that extends to the inner bore; and the lock is slideably received within the slot. 
     Various embodiments are described wherein: the nonthreaded locking feature includes a groove that extends at least part way around the distraction screw; and the nonthreaded aperture of the lock includes a ridge that extends at least part way around an interior surface of the aperture and is sized to fit within the groove of the distraction screw. 
     Various embodiments are described wherein: the distraction screw further includes an enlarged portion that has a diameter that is greater than a diameter of the interior bore; and the second arm further includes a counterbore at an end of the interior bore, the counterbore sized to receive the enlarged portion. 
     Various embodiments are described wherein the distraction screw further includes a driver groove that extends at least part way around the distraction screw and is configured to be engaged by a driver tool. 
     Various embodiments are described wherein: the groove of the nonthreaded locking feature is a square groove; and the driver groove is a round groove. 
     Various embodiments are described wherein the distractor screw further includes a ribbed portion. 
     Various embodiments are described wherein the distractor screw further includes: a flange portion; and a hex portion disposed at a proximal end of the flange portion, wherein the flange portion is wider than the hex portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to better understand various exemplary embodiments, reference is made to the accompanying drawings, wherein: 
         FIG. 1  illustrates a perspective view of an exemplary distractor system; 
         FIG. 2  illustrates a bottom view of the distractor system; 
         FIG. 3  illustrates a perspective view of the distractor system in an alternate configuration; 
         FIG. 4  illustrates a right side view of the distractor system in the alternate configuration; 
         FIG. 5  illustrates a perspective view of an adjustment mechanism of the locking distractor; 
         FIG. 6  illustrates a partial exploded view of the distractor system; 
         FIG. 7  illustrates a top view of an exemplary distraction screw; 
         FIG. 8  illustrates a perspective view of a key; 
         FIG. 9A  illustrates a top view of an arm of the locking distractor in a closed configuration; 
         FIG. 9B  illustrates a cross section of the arm of the locking distractor in the closed configuration; 
         FIG. 9C  illustrates a cross section of the arm of the locking distractor in the closed configuration; 
         FIG. 9D  illustrates a cross section of the arm of the locking distractor in the closed configuration; 
         FIG. 10A  illustrates a top view of an arm of the locking distractor in an open configuration; 
         FIG. 10B  illustrates a cross section of the arm of the locking distractor in the open configuration; 
         FIG. 10C  illustrates a cross section of the arm of the locking distractor in the open configuration; 
         FIG. 10D  illustrates a cross section of the arm of the locking distractor in the open configuration; 
         FIG. 11  illustrates a right side view of an arm of the locking distractor and a distraction screw; 
         FIG. 12  illustrates a cross section of the arm of the locking distractor and the distraction screw in a closed position; 
         FIG. 13  illustrates a cross section of the arm of the locking distractor and the distraction screw in an open position; 
         FIG. 14  illustrates a perspective view of an alternative embodiment of a distractor system; 
         FIG. 15  illustrates a top view of the alternative embodiment of the distractor system; and 
         FIG. 16  illustrates cross section of a distraction screw and an arm of the alternative embodiment of a locking distractor. 
     
    
    
     To facilitate understanding, identical reference numerals have been used to designate elements having substantially the same or similar structure or substantially the same or similar function. 
     DETAILED DESCRIPTION 
     It will be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its scope. Furthermore, all examples recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Additionally, the term, “or,” as used herein, refers to a non-exclusive or (i.e., and/or), unless otherwise indicated (e.g., “or else” or “or in the alternative”). Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. 
       FIG. 1  illustrates a perspective view of an exemplary distractor system  100 . Distractor system  100  may include an exemplary locking distractor  102 , a first distraction screw  104 , and a second distraction screw  106 . Locking distractor  102  may include a crossbar  108 , a stationary arm  110 , and a locking arm  120 . Stationary arm  110  and traveling arm  120  may both constitute distractor arms  110 ,  120 . Stationary arm  110  may include a proximal arm portion  112 , a distal arm portion  114 , and a lock  116 . Traveling arm  120  may include a proximal arm portion  122 , a distal arm portion  124 , a lock  126 , and an adjustment mechanism  128 . 
     Various embodiments herein may be formed from stainless steel. For example, locking distractor  102  may be formed of 17-4 stainless steel, while distraction screws  104 ,  106  may be formed of 316 stainless steel. It will be understood that various alternative materials may be used to form all or part of distraction system  100 . 
     Stationary arm  110  may be coupled to crossbar  108  such that stationary arm  110  does not move with respect to crossbar  108 . For example, proximal arm portion  112  of stationary arm  110  may include a recess sized to receive an end portion of crossbar  108  but not sized to allow the crossbar  108  to advance completely through proximal arm portion  112 . 
     Traveling arm  120  may be coupled to crossbar  108  such that traveling arm  120  is able to move with respect to crossbar  108  and stationary arm  110 . As can be seen in  FIG. 2 , crossbar  108  may pass entirely through proximal arm portion  122  of traveling arm  120 . Traveling arm  120  may slide or otherwise move along crossbar  108 . As will be explained in greater detail below with respect to  FIG. 5 , adjustment mechanism  128  may enable locking of the traveling arm  120  to crossbar  108  and fine adjustments of the position of traveling arm  120  along crossbar  108 . 
     Distractor arms  110 ,  120  may both include multiple portions movably connected to one another. As shown, stationary arm  110  may include proximal arm portion  112  and distal arm portion  114 . Distal arm portion  114  may be hingedly attached to proximal arm portion  112  at a connection point, such as a connecting pin, such that distal arm portion  114  may rotate in one or more planes around the connection point. Various alternative structures for connecting proximal arm portion  112  to distal arm portion  114  will be apparent. 
     As further shown, traveling arm  120  may include proximal arm portion  122  and distal arm portion  124 . Distal arm portion  124  may be hingedly attached to proximal arm portion  122  at a connection point, such as a connecting pin, such that distal arm portion  124  may rotate in one or more planes around the connection point. Various alternative structures for connecting proximal arm portion  122  to distal arm portion  124  will be apparent. 
     As described, the distal arm portions  114 ,  124  may be repositioned to extend in an advantageous direction without repositioning the entire locking distractor  102 . For example, as shown in  FIGS. 3-4 , distal arm portions  114 ,  124  may be rotated to point generally downward with respect to the remainder of locking distractor  102 . Such a configuration may, for example, be advantageous to access the vertebrae of a patent where the locking distractor is mounted above the patient. It will be apparent that various other configurations may be possible. For example, distal arm portions  114 ,  124  may instead be rotated to point generally upward with respect to the remainder of locking distractor  102 . Such a configuration may, for example, be advantageous if the locking distractor  102  were mounted upside down. 
     As will be explained in greater detail below, distraction screws  104 ,  106  may be adapted for insertion into bone. Distraction screws  104 ,  106  may also be sized to be received within distal arm portions  114 ,  124 , respectively. After inserting distraction screws  104 ,  106  into bone and into distal arm portions  114 ,  124 , a surgeon may operate adjustment mechanism  128  to move distractor arms  110 ,  120  toward or away from one another, thereby moving the distraction screws  104 ,  106  and the bones to which distraction screws  104 ,  106  are anchored. 
     It will be appreciated that various alternative embodiments may include alternative combinations of stationary and traveling arms. For example, an alternative distractor may include two traveling arms. As another example, a distractor may include two stationary arms coupled to a mechanism that enables the stationary arms to move with respect to one another. It will further be understood that various alternative embodiments may include fewer or additional arms. For example, an alternative embodiment may include three distractor arms or only one distractor arm. Various alternative embodiments may utilize fewer or additional portions for a distractor arm. For example, a distractor arm may include only one portion and no hinges. As another example, a distractor arm may include three portions that are hingedly connected to each other at two positions. 
       FIG. 5  illustrates a perspective view of an adjustment mechanism  128  of the locking distractor  102 . As shown, crossbar  108  may include a rack of teeth  130 . Connection mechanism may include a ratchet  132  and a pinion  134 . 
     Ratchet  132  may be configured to engage the rack  130  to inhibit movement in one or more directions. Ratchet  132  may include a finger sized to fit between two teeth of rack  130 . Ratchet  132  may be pivotally attached to proximal arm portion  122  and biased such that the finger naturally lies against rack  130 . In this configuration, ratchet  132  may allow movement of adjustment mechanism  128  along crossbar  108  to the left, as viewed in  FIG. 5 , and may prevent movement of adjustment mechanism  128  along crossbar  108  to the right, as viewed in  FIG. 5 . Ratchet  132  may also be manually operable to pivot with respect to proximal arm portion  122 , thereby removing the finger from rack  130  and permitting uninhibited motion of connection mechanism  128  along crossbar  108  in either direction. 
     Pinion  134  may engage rack  130  with mating teeth (not shown). As such, pinion  134  may be manually turned counter clockwise to cause the connection mechanism to travel along crossbar  108  to the right, as viewed in  FIG. 5 . Pinion  134  may also be manually turned clockwise to cause the connection mechanism to travel along crossbar  108  to the left, as viewed in  FIG. 5 . Such motion may be impeded, however, if the ratchet is not released and is currently engaged with rack  130 . 
     It will be understood that various alternative adjustment mechanisms may be employed. For example, an alternative adjustment mechanism may include only ratchet  132  or only pinion  134 . As another example, an alternative adjustment mechanism may constitute a clamp that may be releasably attached at various points along crossbar  108 . 
       FIG. 6  illustrates a partial exploded view of the distractor system  100 . As illustrated, distal arm portion  124  may include an interior bore  136  and a slot  138 . As further illustrated, lock  126  may include a key  140 , spring  142 , and cap  144 . It will be understood that distal arm portion  114  may include a similar interior bore and slot while lock  116  may include a similar key, spring, and cap. 
     Interior bore  136  may be sized to receive distraction screw  106 . Further, slot  138  may extend from the exterior of distal arm portion  124  to the interior bore  136 . In various embodiments, slot  138  may extend from one exterior surface of the distal arm portion  124 , through the interior bore  136 , to the opposite exterior surface of the distal arm portion. Slot  138  may be sized to receive a portion of key  140  therethrough, such that key  140  may be partially disposed within interior bore  136 . 
     As will be described in greater detail below, key  140  may be slidable within slot  138  between an open and a closed position. Spring  142  may be a compression spring and may bias key  140  in the closed position. Cap  144  may attach to the key  140  to prevent spring  142  from ejecting key  140  from slot  138 . 
       FIG. 7  illustrates a top view of an exemplary distraction screw  700 . It will be understood that distraction screw  700  may correspond to either distraction screw  104  or distraction screw  106 . Distraction screw  700  may include a locking feature  702 , driver groove  704 , ribbed portion  706 , hex portion  708 , flange portion  710 , and threaded portion  720 . 
     Locking feature  702  may be a feature configured to be engaged by a lock. As illustrated, locking feature  702  may include a groove having a substantially square profile. This square groove may be sized to receive a ridge of a lock, as will be described in greater detail below. Driver groove  704  may be a feature configured to enable a driver tool (not shown) to engage distraction screw  700 . Driver groove may have a substantially round profile. A driver tool (not shown) may include a round ridge or ring that, when coupled to distraction screw  700 , engages with driver groove  704  to retain the screw  700  within the driver. 
     Ribbed portion  706  may include one or more grooves that provide the body of screw  700  with a plurality of ribs. For example, as shown, ribbed portion  706  may include twenty-six evenly-spaced circular grooves. In various alternative embodiments, ribbed portion  706  may include one or more threads or helical grooves that provide ribs. Ribbed portion  706  may provide additional friction to resist screw  700  falling out of a distractor such as locking distractor  102  or another distractor (not shown) that may or may not include locking features. 
     Hex portion  708  may be wider than other portions of distraction screw  700  and may include six faces. Hex portion may be adapted for engagement with an end of a driver tool (not shown), such that the driver tool may rotate distraction screw  700 , such that distraction screw may be driven into bone. Various alternative configurations for hex portion  708  will be apparent. For example, hex portion  708  may include fewer or additional faces. For example, hex portion  708  may have 10 sides or may be star shaped. 
     Flange portion  710  may be wider than other portions of distraction screw  700 . For example, as shown, flange portion  710  may be the widest portion of distraction screw  700 . Flange portion  710  may provide a stop to indicate when screw  700  has been sufficiently driven into bone and should not be driven further. Additionally, flange portion  710  may provide a surface on which a driver tool (not shown) may rest as the tool acts on hex portion  708 . 
     Threaded portion  720  may include threads  722 ,  724 , one or more flutes  726 , and a pointed tip  728 . Flutes  726  and pointed tip  728  may enable screw  700  to begin driving and cutting threads into bone. Threaded portion  720  may be double threaded to increase the rate at which screw  700  is driven into bone per turn. As such, threaded portion  720  may include a first thread  722  and a second thread  724 . Threads  722 ,  724  may be intertwined with each other to provide for screw  700  to be driven into bone faster and more efficiently. For example, threads  722 ,  724  may have a thread pitch of 1 mm, thereby providing for advancement of the screw  700  by 2 mm per turn. 
       FIG. 8  illustrates a perspective view of a key  800 . Key  800  may correspond to key  140  of lock  126  or to a key of lock  116 . Key  800  may include body  802 , button  804 , and peg  806 . Body  802  may be shaped and sized to be slideably received within a slot of a distal arm portion, such as slot  138  of distal arm portion  124 . Body portion may include an aperture  808  formed therein. Aperture  808  may be large enough to allow at least a portion of a distraction screw, such as screw  700 , to pass therethrough. Aperture  808  may also include a ridge  810  disposed at least part way around the interior of aperture  808 . Ridge  810  may be substantially square or may otherwise be shaped to be received within a locking feature of a distraction screw. For example, ridge  810  of key  800  may be received within locking feature  702  of distraction screw  700 . It will be appreciated that alternative engagements may be used. For example, aperture  808  may instead include a groove (not shown) which may receive a ridge locking feature (not shown) of a distraction screw. 
     Button  804  may be an enlarged portion that is sized to not fit within a slot such as slot  138 . Button  804  may be sized and shaped to be manually pushed in to advance body through a slot such as slot  138 . Peg  806  may be sized and shaped to extend out of a slot and be inserted through a cap (not shown) such as cap  144 . Such cap (not shown) may retain key  800  within the slot so that a spring (not shown) does not force the key  800  back out of the slot. 
       FIG. 9A  illustrates a top view of an arm  110  of the locking distractor  102  in a closed configuration. As shown, lock  116  is not depressed and is biased outward, into the closed position.  FIG. 9B  shows a partial cross-sectional view taken along line B-B. As shown, in the closed configuration, ridge  810  of lock  116  is disposed in line with inner bore  136 .  FIG. 9C  shows a partial cross-sectional view taken along line C-C, while  FIG. 9D  shows a partial cross-sectional view taken along line D-D. As further shown in  FIGS. 9C-D , when in the closed configuration, ridge  810  of lock  116  is disposed in line with inner bore  136 . Thus, when lock  116  is not being acted upon by an external force, lock  116  rests in the closed configuration and ridge  810  may be disposed in line with inner bore  136 . 
       FIG. 10A  illustrates a top view of an arm  110  of the locking distractor  102  in a closed configuration. As shown, lock  116  is depressed to overcome the biasing force and take on the open position.  FIG. 10B  shows a partial cross-sectional view taken along line E-E. As shown, in the open configuration, ridge  810  of lock  116  is not disposed in line with inner bore  136 .  FIG. 9C  shows a partial cross-sectional view taken along line C-C, while  FIG. 9D  shows a partial cross-sectional view taken along line D-D. As further shown in  FIGS. 9C-D , when in the open configuration, ridge  810  of lock  116  pushed out of line with inner bore. Thus, when lock  116  is depressed, lock  116  is disposed in the open configuration and ridge  810  may not be disposed in line with inner bore  136 . As such, a distraction screw (not shown) may be free to slide through the aperture of lock  116  and therefore may slide freely within interior bore  136 . 
     It will be noted that the foregoing description with respect to stationary arm  110  may also be applicable to traveling arm  120 . For example, the lock  126  of traveling arm  120  may operate in a substantially similar manner to that described above with respect to lock  116 . 
       FIG. 11  illustrates a right side view of an arm  110  of the locking distractor  102  and a distraction screw  104 . As shown, distraction screw may be received within distal arm portion  114 . Lock  116  may currently be situated in either the closed position or the open position.  FIG. 12  may illustrate a partial cross section view taken along line A-A when lock  116  is in the closed position. As illustrated, spring  142  may bias key  140  upward, as view in  FIG. 12 , while cap  144  may prevent key from leaving slot  138 . In this closed configuration, ridge  810  of body  140  may engage with locking feature  702  of distraction screw  104 . This engagement may substantially inhibit screw  104  from sliding within interior bore  136 , thereby locking distraction screw  104  in place. 
       FIG. 13  may illustrate a partial cross section view taken along line A-A when lock  116  is in the open position. As illustrated, when a force is applied to body  140  to overcome the biasing force of spring  142 , body  140  may slide through slot  138  to occupy the open position. This sliding may move ridge  810  out of interior bore  136  or out of engagement with locking feature  702 . Thus, when body  140  occupies the open position, screw  104  may freely move within interior bore  136 . 
       FIG. 14  illustrates a perspective view of an alternative embodiment of a distractor system  200 .  FIG. 15  may illustrate a top view of the alternative embodiment of a distractor system  200 . Distractor system  200  may include an exemplary locking distractor  202 , a first distraction screw  104 , and a second distraction screw  106 . Locking distractor  202  may include a crossbar  108 , a stationary arm  210 , and a locking arm  220 . Stationary arm  210  and traveling arm  220  may both constitute distractor arms  210 ,  220 . Stationary arm  210  may include a proximal arm portion  112 , a distal arm portion  214 , and a lock  116 . Traveling arm  120  may include a proximal arm portion  122 , a distal arm portion  224 , a lock  126 , and an adjustment mechanism  128 . 
     Distractor system  200  may differ from distractor system  100  in that distal arm portions  214 ,  224  may be sized and configured to receive more of screws  104 ,  106  than distal arm portions  114 ,  124 . For example, as shown in  FIG. 1 , the hex portions of screws  104 ,  106  may be disposed outside of distal arm portions  114 ,  124 . Returning to  FIGS. 14-15 , the hex portions of screws  104 ,  106  may be disposed inside distal arms portions  214 ,  224 . 
       FIG. 16  may illustrate a partial cross section view taken along line H-H. As shown, distal arm portion  214  may include an interior bore  236  and a counterbore  250 . It will be understood that distal arm portion  224  may include a similar bore and counterbore (not shown). Interior bore  236  may be sized to receive portions of the distraction screw  104 , such as ribbed portion  706 , but may not be sized to receive other portions of the distraction screw  104 , such as hex portion  708 . Counterbore  250  may begin at the distal end of distal arm portion  214  and may be sized to receive at least some of hex portion  708 . As such, hex portion  708  of screw  104  may be recessed within distal arm portion  214  during use. 
     According to the foregoing, various exemplary embodiments enable a distractor that provides a more secure engagement with distraction screws. By providing a biased locking mechanism, a distractor may lock an engagement screw in place within a distractor arm during the performance of a distraction procedure. Further, by providing a distraction screw with intertwined threads, the distraction screw may be introduced into bone more quickly and efficiently. Other advantages will be apparent from the foregoing description. 
     Although the various exemplary embodiments have been described in detail with particular reference to certain exemplary aspects thereof, it should be understood that the invention is capable of other embodiments and its details are capable of modifications in various obvious respects. As is readily apparent to those skilled in the art, variations and modifications can be effected while remaining within the spirit and scope of the invention. Accordingly, the foregoing disclosure, description, and figures are for illustrative purposes only and do not in any way limit the invention, which is defined only by the claims.