Abstract:
A head holder for holding and tensioning the head of a bone screw, particularly a pedicle screw, is provided. Also provided is a ratcheting connector for connecting to the head holders while permitting rotational movement of the head holder when engaged with the ratcheting connector. Also provided is a flex arm connector for connecting multiple ratcheting connectors across multiple vertebral bodies. A tool set for managing and/or correcting spinal deformities, such as scoliosis, including at least one or more head holders and one or more ratcheting connectors is provided.

Description:
BACKGROUND 
       [0001]    The present invention relates to tools and methods for use in performing spinal surgery and, in particular, to tools and methods of using such tools, especially for management and correction of spinal deformities, such as scoliosis. 
         [0002]    Spinal osteosynthesis apparatuses have been utilized to correct spinal deformities, injuries or disease for many years. After the implantation of pedicle screws, a spinal surgeon may insert a metal rod to join a series of vertebral bodies, creating a stable construct and promoting biological fusion of the spinal column. This technique is common for small-level (i.e., “short-construct”) degenerative spinal procedures, as well as multi-level (i.e., “long-construct”) deformity procedures. Spinal deformities often consist of sagittal or coronal curvature, combined with a rotational component along the axis of the spine. Rotational components of a spinal deformity have been addressed using a technique called Direct Vertebral Body Rotation (DVR). However, the tools and methods currently employed in DVR provide challenges. Many such known systems are very technique-dependent and time consuming to implement. It is desirable, therefore, to have a simple-to-use system that produces effective correction of the rotational component of the spinal deformity. 
       SUMMARY 
       [0003]    One aspect of this disclosure relates to a head holder, including a handle portion having generally tubular shape, a distal end and a proximal end; an inner sheath having a tubular proximal end and a distal end having two U-shaped cutouts, two arc-shaped head clamp portions, and one or more pins; and an outer sheath having a distal end and a proximal ring section, the proximal ring section including a locking mechanism which permits the outer sheath to move between and to reside in locked and unlocked positions; wherein the proximal end of the inner sheath is attached to the handle portion, the outer sheath surrounds the inner sheath, a spring surrounds the inner sheath and rests between a distal edge of the handle portion and a proximal edge of the outer sheath. The locking mechanism of the proximal ring section may comprise a locking ring, a set spring, and a locking button. The distal end of the outer sheath may also comprises two opposing U-shaped cutouts for receiving a rod. 
         [0004]    Another aspect of this disclosure relates to a ratcheting connector that includes a first arm comprising an inner section and an outer section, the outer section comprising a first adjustable circular sleeve; a first rotatable bearing rotatably mounted within the first adjustable sleeve; a mechanism to lock the first adjustable circular sleeve around the first rotatable bearing; a second arm comprising an inner section, an outer section, the outer section comprising a second adjustable circular sleeve, and a receptacle having an opening; a second rotatable bearing rotatably mounted within the second adjustable sleeve; a mechanism to lock the second adjustable circular sleeve around the second rotatable bearing; wherein the inner sections of the first and second arms lockably interconnect to permit adjustment of the distance between the first and second circular openings. 
         [0005]    A flex arm connector may be utilized that includes a plurality of nesting cups, each cup having a female portion and a male portion such that a male portion fits within a female portion, the plurality of nesting cups forming a flexible length; a mechanism for locking the flex arm connector into a desired configuration attached to one end of the flexible length; and one or more adjustable sleeves slidably mounted on the flexible length, each sleeve further including a swivel post configured to interlock with a rotation handle receptacle. The adjustable sleeve of the flex arm connector may further comprise a receptacle having an opening, the receptacle located opposite the swivel post. 
         [0006]    A tool set may be utilized to adjust spinal deformities, including one or more head holders that include a handle portion having generally tubular shape, a distal end and a proximal end; an inner sheath having a tubular proximal end and a distal end having two U-shaped cutouts and two arc-shaped head clamp portions; and an outer sheath having a distal end and a proximal ring section, the proximal ring section including a locking mechanism which permits the outer sheath to move between and to reside in locked and unlocked positions; wherein the proximal end of the inner sheath is attached to the handle portion, the outer sheath surrounds the inner sheath, a spring surrounds the inner sheath and rests between a distal edge of the handle portion and a proximal edge of the outer sheath; and one or more ratcheting connectors including a first arm comprising a flat section, and a bent section, the bent section comprising a first adjustable circular sleeve; a first rotatable bearing rotatably mounted within the first adjustable sleeve; a mechanism to lock the first adjustable circular sleeve around the first rotatable bearing; a second arm comprising a flat section, a bent section, the bent section comprising a second adjustable circular sleeve, and a receptacle having an opening; a second rotatable bearing rotatably mounted within the second adjustable sleeve; a mechanism to lock the second adjustable circular sleeve around the second rotatable bearing; wherein the flat sections of the first and second arms interconnect to permit adjustment of the distance between the first and second circular openings. 
         [0007]    The tool set may further includes a flex arm connector comprising a plurality of nesting cups, each cup having a female portion and a male portion such that a male portion fits within a female portion, the plurality of nesting cups forming a flexible length; a mechanism for locking the flex arm connector into a desired configuration attached to one end of the flexible length; one or more adjustable sleeves slidably mounted on the flexible length, each sleeve further including a swivel post and rotation handle opening. The tool set may further include one or more rotation handles interconnectable with the rotation handle opening. 
         [0008]    A tool set for the adjustment of spinal deformities can be utilized that comprises one or more head holders that include a handle portion having generally tubular shape, a distal end and a proximal end; an inner sheath having a tubular proximal end and a distal end having two U-shaped cutouts and two arc-shaped head clamp portions; and an outer sheath having a distal end and a proximal ring section, the proximal ring section including a locking mechanism which permits the outer sheath to move between and to reside in locked and unlocked positions; wherein the proximal end of the inner sheath is attached to the handle portion, the outer sheath surrounds the inner sheath, a spring surrounds the inner sheath and rests between a distal edge of the handle portion and a proximal edge of the outer sheath; and one or more ratcheting connectors including a first arm comprising a flat section, and a bent section, the bent section comprising a first adjustable circular sleeve; a first rotatable bearing rotatably mounted within the first adjustable sleeve; a mechanism to lock the first adjustable circular sleeve around the first rotatable bearing; a second arm comprising a flat section, a bent section, the bent section comprising a second adjustable circular sleeve, and a receptacle having an opening; a second rotatable bearing rotatably mounted within the second adjustable sleeve; a mechanism to lock the second adjustable circular sleeve around the second rotatable bearing; wherein the flat sections of the first and second arms interconnect to permit adjustment of the distance between the first and second circular openings; a flex arm connector comprising a plurality of nesting cups, each cup having a female portion and a male portion such that a male portion fits within a female portion, the plurality of nesting cups forming a flexible length ;a mechanism for locking the flex arm connector into a desired configuration attached to one end of the flexible length; one or more adjustable sleeves slidably mounted on the flexible length, each sleeve further including a swivel post and rotation handle opening; and one or more rotation handles interconnectable with the rotation handle opening. 
     
    
     
       DRAWINGS 
         [0009]      FIG. 1  is an exploded view of an embodiment of a head holder suitable for use with the disclosed invention. 
           [0010]      FIG. 2  is an exploded view of an embodiment of a ratcheting connector suitable for use with the disclosed invention. 
           [0011]      FIG. 3  is a perspective view of an embodiment of a ratcheting connector suitable for use with the disclosed invention. 
           [0012]      FIG. 4  is a perspective view of an embodiment of a flex arm connector suitable for use with the disclosed invention. 
           [0013]      FIG. 5  is a perspective view of a portion of the flex arm connector shown in  FIG. 4 . 
           [0014]      FIG. 6  is a perspective view of an embodiment of a tool set suitable for use with the disclosed invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Referring first to  FIG. 1 , an embodiment of a novel head holder  1  is shown in an exploded view. The head holder includes a handle  3 , an inner sheath  5 , and an outer sheath  7 . Inner sheath  5  may comprise a tubular section  9  that, in the assembled head holder  1 , is proximate to the handle  3 , and a distal portion  11  configured to grip the head of a bone screw and more particularly, a pedicle screw. As shown, distal portion  11  includes two cutout portions  13  that allow the most distal end of the inner sheath  5  to flex in order to grasp the head of the bone screw. A head clamp portion  14  may be located at the most distal end of inner sheath  5 . Head clamp portion  14 , as shown in  FIG. 1 , includes two arc-shaped portions  15 . The arc-shaped portions  15  may extend axially outward from the distal portion  11 . Each arc-shaped portion  15  may further include an opening  17 , through which a pin  19  may be mated. Pin  19  may extend axially into the inner sheath  5 . Pin  19  may be configured to mate with or interlock with a spinal implant, such as a pedicle screw. 
         [0016]    Referring still to  FIG. 1 , handle  3  is generally tubular in construction with a proximal portion optionally covered in a comfortable gripping material or surface treatment  21 . Handle  3  further includes a distal end  23 , that may comprise a tapered or narrower outer diameter than the proximal portion, configured so as to fit within the inside diameter of outer sheath  7 . Distal end  23  of handle  3  further includes two grooves  25   a  and  25   b,  corresponding to locked and unlocked positions, respectively. 
         [0017]    In its assembled configuration, a spring  27  is loaded between outer sheath  7  and handle  3 . Inner sheath  5  is then passed into the tubular opening of outer sheath  7 , engaging within the tubular opening of handle  3 . Outer sheath  7  is maintained in either a locked or unlocked position by locking means. As shown in  FIG. 1 , the locking means includes a set spring  31 , a locking ring  33 , and a locking button  35 . Outer sheath  7  includes a proximal ring section  39  having an opening through which locking ring  33  passes. Outer sheath  7  further includes a distal portion optionally having U-shaped channels  41  to fit over a rod when head holder  1  is engaged in the locked position on a pedicle screw head. 
         [0018]    The head holder  1  provides a secure connection to the head of a pedicle screw and allows for leverage during the surgeon&#39;s application of a rotational force. Because the head holder  1  includes a conveniently located and readily operable locking means, the head holder may be used in an initial unlocked position prior to attachment to the pedicle screw head and is easily locked following attachment to the pedicle screw head. Moreover, because of the shape of the head clamp portion  13 , the head holder  1  may be connected to a pedicle screw head after the rod has been placed in pedicle screw head. 
         [0019]    To utilize the head holder  1 , the surgeon sets the outer sleeve to the unlocked configuration, i.e., locking ring  33  is depressed thereby relieving the clumping of outer sheath  7  on inner sheath  5 . As the head holder  1  approaches the pedicle screw head, the inner sheath  5  makes contact with the top surface of the pedicle screw head. An axial force is applied along the axis of the head holder  1 , causing the inner sheath  5  to open and accept the diameter of the pedicle screw head. The head holder  1  is advanced until the pins  19  make contact with mating features on the pedicle screw head. Once engaged, the locking button  35  is pressed to activate the spring loaded outer sheath  7 . The outer sheath  7  is propelled along the axis of the head holder  1  until locked in place around the inner sheath  5 . Undercuts  25   a  and  25   b  on handle  3  allow the outer sheath  7  to be held in unlocked and locked positions. 
         [0020]    In order to disconnect the head holder  1  from a bone screw head, the locking button  35  is pressed and the outer sheath  7  is pulled up the axis of the head holder  1  towards the proximal end of the handle  3  until it reaches the unlocked position. A pulling force is applied along the axis of the head holder  1 , allowing the inner sheath  3  to readily and easily separate and disengage from the pedicle screw head. 
         [0021]    Referring now to  FIG. 2 , an exploded view of a first embodiment of the novel ratcheting connector  50  is shown. The ratcheting connector  50  provides a means of connecting pairs of head holders  1  located on a single vertebral body. The ratcheting connector  50  may account for variability in pedicle screw trajectory and effectively distributes rotational forces over two pedicle screws rather than focusing the load on single pedicle screw. Various embodiments of the ratcheting connector  50  further permits one or more of the following benefits: transverse plane adjustment (lock/unlock) for distance between pedicle screws, sagittal plane adjustment (lock/unlock) for variability in trajectory of pedicle screws, simple tightening and locking mechanisms for each plane of adjustment, and a centralized spring loaded receptacle for utilization of rotation handle or, optionally, a flexible arm connector. 
         [0022]    Referring still to  FIG. 2 , the first embodiment of the ratcheting connector  50  includes two interconnecting arms  51   a  and  51   b,  each arm  51  having a inner sections  53   a  and  53   b  and outer sections,  55   a  and  55   b,  which can be bent downward. The interconnecting arms  51   a  and  51   b  both have generally rectangular cross sections that allow the inner sections  53   a  and  53   b  to be slidably connected to each other. Also visible in  FIG. 2  is the substantially flat profile of the inner sections  53   a  and  53   b.  Each outer section has a circular sleeve,  57   a  and  57   b,  the diameter of which is slightly adjustable with a sagittal plane adjustment knob,  59   a  and  59   b . Inside circular sleeves  57   a  and  57   b  are rotatable bearings  61   a  and  61   b,  respectively. Bearings  61   a  and  61   b  have curved outer surfaces allowing them to partially rotate within circular sleeves  57   a  and  57   b.  Inner section  53   a  interconnects with inner section  53   b  in a manner allowing the distance between circular sleeves  57   a  and  57   b  to be adjustable. The distance between circular sleeves  57   a  and  57   b  may be locked into place by locking plate  63 . Likewise, the distance between  57   a  and  57   b  may be allowed to change by unlocking plate  63 . Any adjustable interconnecting mechanism may be used. For example, in one embodiment of ratcheting connector  50 , flat section  53   a  has a toothed lower edge  63 , as shown in  FIG. 3 , the teeth of which may engage a pin (not shown) projecting inwardly from an inside surface of flat section  53   b.  Also visible in  FIG. 3  is the substantially curved profiles of the inner sections  53   a  and  53   b.    
         [0023]    Embodiments of the ratcheting connector  50  may optionally include a receptacle  67  (as shown in  FIGS. 2 and 3 ). Receptacle  65  includes an opening  67  in its top surface to permit insertion of a rotation handle or flexible arm connector. In some embodiments, receptacle  65  further includes a mechanism to releasably lock the rotation handle or flexible arm connector in opening  67 . Such mechanism may be implemented as a spring loaded button  73 . 
         [0024]    To utilize the ratcheting connector  50 , the surgeon sets the transverse plane locking plate  63  the unlocked position. The rotatable bearings  61   a  and  61   b  at each end of the ratcheting connector  50  are placed over the proximal ends of two head holders  1  on a single vertebral body. Transverse plane adjustment is achieved by pushing or pulling the rotating clamps in relation to each other. Once the desired configuration has been reached, the plane orientation can be locked by moving the locking plate  63  into the locked position to prevent further movement of the flat sections  53   a  and  53   b.  Sagittal plane adjustment can be achieved by rotating the rotatable bearings  61   a  and  61   b  to the desired trajectory or angle with respect to sleeves  57   a  and  57   b.  Once the desired configuration has been reached, the sagittal plane adjustment knob  59   a  and  59   b  can be locked thereby tightening the sleeves  57   a  and  57   b  onto rotatable bearings  61   a  and  61   b  respectively. The receptacle  65  at the top of the ratcheting connector allows for the utilization of a rotation handle or flex arm connector (as shown in  FIG. 5 ). 
         [0025]    To disconnect the ratcheting connector  50  from the head holders  1 , the sagittal plane adjustment knobs  59   a  and  59   b  are unlocked and the transverse plane locking plate  63  is also unlocked. Once all adjustments have been loosened, the ratcheting connector  50  slips off over the proximal end of each head holder  1 . 
         [0026]    Referring now to  FIG. 4 , a perspective view of the flex arm connector  80  is shown. Flex arm connector  80  provides a means of connecting a series of ratcheting connectors  50  located on consecutive vertebral bodies. The flex arm connector  80  can account for variability in rotation in consecutive vertebral bodies and effectively distributes rotational forces over multiple vertebral bodies rather than focusing the load on a single vertebral body. Various embodiments of the flex arm connector  80  further permits one or more of the following benefits: sagittal plane adjustment for off axis location of pedicle screws on consecutive vertebral bodies; transverse/coronal plane adjustment for variance in rotation between consecutive vertebral bodies; simple tightening and locking mechanism for each plane of adjustment; and centralized receptacle for optional utilization of a rotation handle. 
         [0027]    Referring to  FIG. 5 , a perspective view of a portion of a flex arm connector  80  is shown. In preferred embodiments, the flex arm connector is made of a plurality of nesting cups  81 . Each cup includes a male portion  83  and a female portion  85 , with the male portion of one nesting cup fitting rotatably within the female portion of a proximate nesting cup. The length of the flex arm connector  80  is adjustable, prior to use, by adding or removing nesting cups  81 . 
         [0028]    Referring again to  FIG. 4 , a flex arm connector for use with four ratcheting connectors  50  is shown. At one end of the flex arm connector  80  is a locking mechanism  97 , engagement of which causes the flex arm connector  80  to become rigid in the position in which it is placed. Optionally, at an opposite end of the flex arm connector  80  is a terminal sleeve  89 . Adjustable sleeves  87  can be placed at desired locations along the flex arm connector  80  and locked into place, by means of, for example, a set screw. Each of adjustable sleeves  87  and terminal sleeve  89  includes a swivel post  93 . Swivel posts  93  optionally include a tapered end  91  and means for interlocking, such as ridges and/or grooves, with receptacle opening  67  of  FIG. 2 . Swivel posts  93  further include rotation handle openings  95  which are configured to accept rotation handles  90  ( FIG. 6 ). In some embodiments of the flex arm connector  80 , a rotation handle receptacle  95  is provided that includes an opening to receive a rotation handle. 
         [0029]    To utilize the flex arm connector  80 , the surgeon inserts the swivel posts  91  into the receptacle opening  67  ( FIG. 2 ) of the ratcheting connectors  50  (See  FIG. 6 ). Sagittal plane adjustment can be achieved by sliding the adjustable sleeves  87  along the axis, or length, of the flex arm connector  80  and inserting swivel posts  91  into the receptacle openings  67  on ratcheting connectors  50  on consecutive vertebral bodies. Sagittal plane adjustment can be achieved using the flexible cable and segments to trace the trajectory of the previously attached ratcheting connectors on consecutive vertebral bodies. The sagittal trajectory can be locked by engaging locking mechanism  97 . 
         [0030]    To disconnect the flex arm connector  80  from the ratcheting connectors  50 , the transverse plane adjustment is unlocked by disengaging locking mechanism  97  so that the flex arm connector is no longer rigid. The swivel posts  91  can then be removed from the receptacle openings  67  of the ratcheting connectors  50 . In some embodiments, it may be desirable to disengage any locking mechanism of the receptacle  65 . 
         [0031]    Referring now to  FIG. 6 , an embodiment of a tool set of the present invention is shown. As shown in  FIG. 6 , the tool set includes four head holders  1 , two ratcheting connectors  50 , and a flex arm connector  80 .  FIG. 6  further shows rotation handles  90  that interlock with rotation handle openings  95  ( FIG. 4 ). 
         [0032]    It will be understood that various embodiments of the invention may include varying numbers of head holders and ratcheting connectors, depending upon the length of spinal adjustment needed. Moreover, it will be understood that a flex arm connector may not be included in all embodiments of the tool set of the present invention. Rather, certain embodiments may include solely head holders and ratcheting connectors and rotation handles.