Patent Publication Number: US-2023149046-A1

Title: Reduction system for spondylolisthesis

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a continuation application claiming priority benefit, with regard to all common subject matter, of U.S. patent application Ser. No. 17/525,464, filed Nov. 12, 2021, and entitled “REDUCTION SYSTEM FOR SPONDYLOLISTHESIS.” The above-referenced application is hereby incorporated by reference in its entirety into the present application. 
    
    
     TECHNICAL FIELD 
     Embodiments of the invention generally relate to a system and method for treating a spinal condition. More specifically, embodiments of the invention relate to systems and methods for spondylolisthesis reduction. 
     RELATED ART 
     The spine consists of a column of twenty-four vertebrae that extend from the skull to the hips. Discs of soft tissue are disposed between adjacent vertebrae. In addition, the spine encloses and protects the spinal cord, defining a bony channel around the spinal cord, called the spinal canal. 
     Over time, at birth, or due to injury, two vertebrae within the spine may become displaced against one another, resulting in a condition known as spondylolisthesis. Spondylolisthesis typically refers to a first vertebra that is displaced anteriorly against a second vertebra, while retrolisthesis refers to the first vertebra displacing posteriorly against the second vertebra. Typically, spondylolisthesis occurs in the lumbar spine at the L5-S1 level where the L5 vertebra displaces forward over the S1 vertebra. Spondylolisthesis can also occur between other vertebrae, such as, for example, between the L4 and L5 vertebrae, between the L3 and L4 vertebrae, or via the hangman&#39;s fracture wherein the C2 vertebra displaces anteriorly relative to the C3 vertebra due to the fracturing of the C2 vertebra&#39;s pedicles. 
     The posterior portion of a vertebra consists of eleven vertebral parts, including two pedicles, two laminae, and seven processes. One pedicle and one lamina are present on each side of the spinal cord. The seven processes consist of one spinous process, two transverse processes, and four articular processes. The spinous process extends posteriorly from the vertebra. The two transverse processes are on opposing sides of the vertebra and project laterally at the point where the lamina meets the pedicle. The articular processes extend from the junctions of the pedicles and the laminae and can be categorized into superior articular processes that extend upwards and inferior articular processes that extend downwards, with one super articular process and one inferior articular process on each side of the spinal cord. The superior articular process from one vertebra connects to the interior articular processes from the vertebra directly above. 
     Various methods have been developed to treat spondylolisthesis. Often patients are instructed to perform non-operative treatments such as physical therapy, exercise, and bracing to relieve pain or discomfort. Medication such as nonsteroidal anti-inflammatories, analgesics, and steroids may also be used. When spondylolisthesis becomes severe, operative treatments may be required to correct the vertebra slippage. Traditional surgical approaches typically involve open surgeries with direct decompression and instrumented fusion of the spine. Such surgeries include anterior, posterior, or transforaminal lumbar interbody fusion. When treating spondylolisthesis, open surgery may lead to the destabilization of surrounding bony support structures, such as the facet joints of the spine. Percutaneous or minimally invasive processes have become a popular alternative over open surgery for treating spondylolisthesis and can reduce surgical trauma, postoperative complications, and hospital stay that may occur as a result of open surgery. Lumbar interbody fusion surgeries may also be performed using minimally invasive techniques. 
     Spondylolisthesis correction typically involves spinal fusion of the two vertebrae afflicted by spondylolisthesis. Spinal fusion may involve an interspinous implant that allows for the fixation of the thoracic, lumbar, and sacral spine while waiting for bony fusion to occur. Examples of a particularly useful interspinous process implant and fusion devices are disclosed in commonly assigned U.S. Pat. No. 9,861,399, 8,945,184 (“the &#39;184 Patent”), U.S. Pat. Nos. 9,314,276, 9,907,581, 9,757,164, and U.S. patent application Ser. No. 16/998,171, which was filed on Aug. 8, 2020, and is entitled ‘INTERSPINOUS PROCESS IMPLANT’, the disclosures of which are all incorporated herein by reference in their entirety. 
     SUMMARY 
     Embodiments of the invention address the above-identified need by providing systems and methods for spondylolisthesis reduction. A spondylolisthesis reduction system may comprise a bracket, rods, and knobs. The bracket may be placed on a patient&#39;s back. The rods may be inserted into corresponding openings in the bracket and further into the patient&#39;s back. A knob may be threaded onto each rod configured to pull the rods, thereby repositioning a vertebra to reduce spondylolisthesis. Once repositioned, a spinal implant may be inserted into the patient to promote spinal fusion. 
     A first embodiment is directed to a spondylolisthesis reduction system comprising: a first bracket configured to be placed onto the back of a patient, the first bracket comprising at least one opening; a first rod being received through the at least one opening, said first rod having a sharpened distal end configured to be inserted into a first vertebral part of a first vertebra; and a first knob having a first lumen therethrough, said first knob receiving the first rod through the first lumen. When said first knob is tightened onto the first rod, said first knob abuts the first bracket, pulls the first rod proximally, and is configured to reposition the first vertebra. 
     Another embodiment is directed to a spondylolisthesis reduction system comprising a bracket configured to be placed onto a patient, the bracket comprising a first opening and a second opening, a first rod configured to be inserted through the first opening and into a first vertebral part of a vertebra, a second rod configured to be inserted through the second opening and into a second vertebral part of the vertebra, a first knob configured to be tightened onto the first rod to pull the first rod, and a second knob configured to be tightened onto the second rod to pull the second rod. The pulling of at least one of the first rod or the second rod is configured to reposition the vertebra. 
     Another embodiment is directed to a method for spondylolisthesis reduction comprising placing a bracket onto a patient, the bracket comprising a first opening and a second opening, inserting a first rod through the first opening and into a first vertebral part of a vertebra, inserting a second rod through the second opening and into a second vertebral part of the vertebra, tightening a first knob onto the first rod to pull the first rod, and tightening a second knob onto the second rod to pull the second rod, and pulling at least one of the first rod and the second rod to reposition the vertebra. 
     Another embodiment is directed to a system for spondylolisthesis reduction comprising a first bracket configured to be placed onto a patient substantially over a first vertebral part of a vertebra, a second bracket configured to be placed onto a patient substantially over a second vertebral part of the vertebra, a first rod configured to be inserted through the first bracket and into the first vertebral part, a second rod configured to be inserted through the second bracket and into the second vertebral part, and a first knob configured to pull the first rod, a second knob configured to pull the second rod, wherein pulling at least one of the first rod and the second rod is configured to reposition the vertebra. In some embodiments, the system further includes an interspinous implant configured to be inserted into the patient after the vertebra has been repositioned. 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other aspects and advantages of the current invention will be apparent from the following detailed description of the embodiments and the accompanying drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein: 
         FIG.  1    illustrates a spondylolisthesis reduction system for certain embodiments; 
         FIG.  2    illustrates a rod for use in the spondylolisthesis reduction system for certain embodiments; 
         FIG.  3 A  illustrates a first embodiment of a bracket for use in the spondylolisthesis reduction system; 
         FIG.  3 B  illustrates a second embodiment of the bracket for use in the spondylolisthesis reduction system; 
         FIG.  4 A  illustrates a knob for use in the spondylolisthesis reduction system for certain embodiments; 
         FIG.  4 B  illustrates a cross-sectional view of the knob for certain embodiments; and 
         FIG.  5    illustrates an exemplary method for reducing spondylolisthesis for certain embodiments. 
     
    
    
     The drawing figures do not limit the invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention. 
     DETAILED DESCRIPTION 
     The subject matter of the invention is described in detail below to meet statutory requirements; however, the description itself is not intended to limit the scope of claims. Rather, the claimed subject matter might be embodied in other ways to include different steps or combinations of steps similar to the ones described in this document, in conjunction with other present or future technologies. Minor variations from the description below will be understood by one skilled in the art and are intended to be captured within the scope of the claimed invention. Terms should not be interpreted as implying any particular ordering of various steps described unless the order of individual steps is explicitly described. 
     The following detailed description of embodiments of the invention references the accompanying drawings that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense. The scope of embodiments of the invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled. 
     In this description, references to “one embodiment,” “an embodiment,” or “embodiments” mean that the feature or features being referred to are included in at least one embodiment of the technology. Separate reference to “one embodiment” “an embodiment”, or “embodiments” in this description do not necessarily refer to the same embodiment and are also not mutually exclusive unless so stated and/or except as will be readily apparent to those skilled in the art from the description. For example, a feature, structure, or act described in one embodiment may also be included in other embodiments but is not necessarily included. Thus, the technology can include a variety of combinations and/or integrations of the embodiments described herein. 
     Embodiments are generally directed to a method and system for spondylolisthesis reduction. In some embodiments, the reduction system comprises a bracket placed substantially over a displaced vertebra. Two rods, each of which may be inserted into a vertebral part of the displaced vertebra, may be inserted through the bracket and into the vertebral parts. In some embodiments, the vertebral parts are on opposite sides of the spinal cord. The bracket may serve to keep the two rods substantially in place during the reduction procedure. A knob may be threaded onto each rod to pull the rods posteriorly, thereby repositioning the vertebra. Threading the knobs down the rods may create leverage against the bracket to facilitate the pulling of the rods and the repositioning of the vertebra. In some embodiments, the spondylolisthesis reduction process is performed posteriorly. In some embodiments, the displaced vertebra is repositioned to allow for an interspinous spinal implant to be inserted into the spine. Retrolisthesis may also be corrected using embodiments described herein. 
       FIG.  1    illustrates a reduction system  100  for treating spondylolisthesis for some embodiments. In some embodiments, reduction system  100  comprises a first rod  102   a , a second rod  102   b , a first knob  104   a , a second knob  104   b , and bracket  106 . As described above, to facilitate spondylolisthesis reduction, first rod  102   a  may be inserted into first vertebral part  108   a  and second rod  102   b  may be inserted into second vertebral part  108   b . In some embodiments, first vertebral part  108   a  and second vertebral part  108   b  are vertebral parts of first vertebra  110 . In some embodiments, first vertebra  110  is the slipped or displaced vertebra causing spondylolisthesis. In some embodiments, vertebral parts  108   a ,  108   b  are one of the laminae, pedicles, or the transverse processes. Once rods  102   a ,  102   b  are in place, knobs  104   a ,  104   b  may then be translated down rods  102   a ,  102   b  via a rotational force, thus pulling rods  102   a ,  102   b  posteriorly from the patient and allowing first vertebra  110  to be repositioned. In some embodiments, the various components of reduction system  100  are interchangeable. For example, first rod  102   a  may be inserted into second vertebral part  108   b , and second knob  104   b  may be threaded onto first rod  102   a  to reposition second vertebral part  108   b.    
     To facilitate spondylolisthesis reduction using reduction system  100 , bracket  106  may be arranged onto a patient&#39;s back prior to inserting rods  102   a ,  102   b  into the patient. Bracket  106  may be positioned on the patient substantially over the location of the first vertebra  110  that is to be repositioned. In some embodiments, imaging systems, such as fluoroscopy, three-dimensional imaging, computed tomography (CT) scanning, robotics, or any combination thereof, are utilized to aid in correctly positioning bracket  106  and other components of reduction system  100  described herein. Once bracket  106  is in place, rods  102   a ,  102   b  may be inserted through the patient&#39;s tissue and into the vertebral parts  108   a ,  108   b . In some embodiments, rods  102   a ,  102   b  may be inserted into the patient before bracket  106  is placed onto the patient, and bracket  106  is then placed over rods  102   a ,  102   b.    
     In some embodiments, bracket  106  is substantially rectangular with rounded ends and comprises openings  308   a ,  308   b  for receiving rods  102   a ,  102   b  therein. In some embodiments, bracket  106  has a width of about 10 mm to about 20 mm, or about 20 mm to about 30 mm. In some embodiments, bracket  106  has a thickness of about 10 mm to about 20 mm, or about 20 mm to about 30 mm. In some embodiments, bracket  106  has a length of about 190 mm to about 205 mm, or about 205 mm to about 220 mm. In some embodiments, bracket  106  is about 17 mm thick, about 17 mm wide, and about 202 mm long. In some embodiments, bracket  106  comprises a substantially similar width and thickness. In some embodiments, bracket  106  may be oval, circular, or rectangular, or have any other desired shape. 
     In some embodiments, when rods  102   a ,  102   b  are tightened, such as by threading knobs  104   a ,  104   b , bracket  106  may be leveraged against the patient&#39;s back, thus allowing rods  102   a ,  102   b  to adjust and reposition first vertebra  110  to correct spondylolisthesis or another deformity. In some embodiments, bracket  106  may be curved, arched, concave, or otherwise formed such that bracket  106  is configured to substantial conform to the shape of the patient&#39;s back. In some embodiments, bracket  106  may have a curvature of about 20° to about 25°, about 25° to about 30°, or about 30° to about 35°. In some embodiments, the curvature for bracket  106  is about 27°. As will be discussed further below, in some embodiments, bracket  106  may be replaced by two brackets with a first bracket for receiving first rod  102   a  and a second bracket for receiving second rod  102   b.    
     In some embodiments, as seen in  FIG.  2   , rods  102   a ,  102   b  may be substantially cylindrical having a distal section  204  and a proximal section  202 . During use, distal section  204  is configured to connect to vertebral parts  108   a ,  108   b  and a proximal section  202  is configured to remain outside of the patient&#39;s body. In some embodiments, rods  102   a ,  102   b  may have a circular, oval, rectangular, pentagonal, or hexagonal cross-sectional shape. In some embodiments, rods  102   a ,  102   b  may have any longitudinal form. In some embodiments, rods  102   a ,  102   b  may have a length of about 200 mm to about 250 mm, or about 250 mm to about 300 mm. In some embodiments, rods  102   a ,  102   b  may be about 250 mm in length. In some embodiments, rods  102   a ,  102   b  may have a diameter of about 2 mm to about 5 mm, or about 5 mm to about 8 mm. In some embodiments, rods  102   a ,  102   b  are about 5 mm in diameter. In embodiments where rods  102   a ,  102   b  are not cylindrical, rods  102   a ,  102   b  may be about 2 mm to about 8 mm wide at a widest point. In some embodiments, rods  102   a ,  102   b  may have a varying diameter or a varying cross-sectional area. In some embodiments, the diameter or cross-sectional area may be larger at the proximal end than at the distal end. 
     In some embodiments, rods  102   a ,  102   b  may be sanitized and/or sterilized prior to use to ensure no contaminants or bacteria are transferred to the patient. For example, rods  102   a ,  102   b  may be sterilized using standard surgical processes such as autoclaving, γ-irradiation, steam, ethylene oxide, hydrogen peroxide gas plasma, peracetic acid immersion, ozone sterilization techniques, or any combination thereof. Bracket  106  and knobs  104   a ,  104   b  may undergo similar sterilization procedures, either separately or together. 
     As described above, knobs  104   a ,  104   b  may be tightened onto rods  102   a ,  102   b  to pull rods  102   a ,  102   b  posteriorly, thus allowing first vertebra  110  to be repositioned. In some embodiments, knobs  104   a ,  104   b  may be substantially cylindrical in shape as shown, but include flat faces  402 ,  403  for enhancing gripping. In some embodiments, knobs  104   a ,  104   b  are substantially square, rectangular, spherical, or any other geometrical shape. As will be discussed further below with respect to  FIG.  4 A , knobs  104   a ,  104   b  may comprise a central lumen  410  for receiving a rod  102   a ,  102   b  therein. The lumen  410  may comprise internal threads  412  for cooperating with external threads  210  on rods  102   a ,  102   b . Broadly, knobs  104   a ,  104   b  may take any geometric shape and comprise various dimensions provided that knobs  104   a ,  104   b  are capable of cooperating with rods  102   a ,  102   b  to pull  102   a ,  102   b  against bracket  106 . 
     As described above, spondylolisthesis may occur between various adjacent vertebrae within the spine. In some embodiments, first vertebra  110  is considered to have “slipped” relative to a lower second vertebra  112 . As described above, rods  102   a ,  102   b  may be inserted into the lamina, pedicle, transverse process, or other vertebral parts  108   a ,  108   b  of first vertebra  110 . In some embodiments, first rod  102   a  is inserted into a different vertebral part than second rod  102   b . For example, first rod  102   a  may be inserted into the lamina of first vertebra  110 , while second rod  102   b  may be inserted into the pedicle of first vertebra  110 . 
     In some embodiments, reduction system  100  is provided as a kit and packaged for surgical use. Each component of reduction system  100  is sterilized for single use or multiple uses. In some embodiments, at least a portion of reduction system  100  may be configured for reuse in the operating room, such as knobs  104   a ,  104   b  and/or bracket  106 . In some embodiments, rods  102   a ,  102   b  are configured to be single use only. In some embodiments, reduction system  100  is entirely disposable and configured for single use only. Reduction system  100  may further comprise an interspinous implant that is inserted into the spine of the patient once reduction system  100  has repositioned first vertebra  110 , as will be discussed in further detail below. 
     Turning now to  FIG.  2   , an exemplary first rod  102   a  is illustrated for certain embodiments. In some embodiments, rods  102   a ,  102   b  are substantially similar. In some embodiments, rods  102   a ,  102   b  may comprise various metals such as stainless steel, titanium, titanium alloys, steel, aluminum, aluminum alloys, or a combination thereof. In some embodiments, rods  102   a ,  102   b  comprise polymers such as acetal copolymer, polyether ether ketone (PEEK), polycarbonate, polypropylene, polyphenylsulfone, polytetrafluoroethylene (PTFE), polysulfone, polyphenylene sulfide, polyvinylidene fluoride, polyetherimide, polyphenylene oxide, or any combination thereof. In still other embodiments, rods  102   a ,  102   b  may comprise ceramics such as zirconia, bioglass, alumina, hydroxyapatite, or any combination thereof. 
     In some embodiments, first rod  102   a  comprises proximal section  202  and distal section  204 . During use, distal section  204  is configured to contact first vertebral part  108   a  when first rod  102   a  is inserted into the patient. Proximal section  202  includes proximal end  206 . In some embodiment, proximal end  206  may comprise a substantially flat face. In some embodiments, proximal end  206  is substantially blunt, spherical, conical, squared, rectangular, triangular, or any other geometrical shape. Proximal end  206  may be configured to attach to a handle  109 , such as a quick connect handle, via a push-to-connect, a push-fit, or other similar connecting means. In some embodiments, proximal end  206  itself serves as the handle. In some embodiments, proximal end  206  may be formed to have a t-handle shape or a teardrop handle shape. In some embodiments, at least a portion of proximal end  206  is hollow to allow for the insertion of a handle therein. In some embodiments, the handle assists in inserting first rod  102   a  into the patient&#39;s back and further into first vertebral part  108   a . The handle may be rotated, thus driving first rod  102   a  downwards. In some embodiments, the handle  109  may be a t-handle, a tear drop handle, a tapered handle, a ratchet handle, a crank handle, or any handle operable to rotationally drive first rod  102   a  into first vertebral part  108   a . In some embodiments, first rod  102   a  is pushed into the patient and further into first vertebral part  108   a  via an axial force applied near proximal end  206 . In some embodiments, once first rod  102   a  has been fully inserted into first vertebral part  108   a , the handle (if present) may be removed from proximal end  206 , and first knob  104   a  may be subsequently attached onto first rod  102   a . In some embodiments, first knob  104   a  is already on the first rod  102   a  before the handle is attached, and the handle may remain in place throughout the operation. 
     Distal section  204  terminates in distal tip  208 . In some embodiments, distal tip  208  may be a substantially sharp tip capable of being at least partially inserted into vertebral parts  108   a ,  108   b . In some embodiments, distal tip  208  may include sharp threads  211  on an outer surface. In some embodiments, distal tip  208  is substantially conical or triangular. In some embodiments, prior to insertion of first rod  102   a , a pilot hole is drilled into first vertebral part  108   a  for inserting distal tip  208  therein. In some embodiments, distal tip  208  is a self-drilling tip and comprises a drill-shaped point to cut through bone, thereby eliminating the need for drilling a pilot hole. In some embodiments, distal tip  208  may be removable from distal section  204  and may be interchanged with at least one other distal tip  208 . For example, a self-drilling distal tip  208  may be replaced with a distal tip  208  configured for use with a pilot hole depending on the desired application. Removable distal tip  208  may be removably attached to the distal section  204  by a threaded interconnection or any other mechanical connection means. 
     In some embodiments, distal tip  208  comprises various features for enhancing attachment to first vertebral part  108   a . For example, distal tip  208  may comprise threads, fangs, teeth, and/or hooks for attaching to first vertebral part  108   a . In some embodiments, distal tip  208  may comprise a different material than proximal section  202  and/or distal section  204 . For example, proximal section  202  and/or distal section  204  may comprise a polymer or a plastic and distal tip  208  may comprise a substantially hard metal capable of insertion into vertebral parts  108   a ,  108   b.    
     In some embodiments, first rod  102   a  comprises external threads  210 . As illustrated, external threads  210  may be present on the outer surface of at least a portion of first rod  102   a . In some embodiments, external threads  210  may extend throughout the entirety of both proximal section  202  and distal section  204 . In some embodiments, external threads  210  may extend partially into proximal section  202  and throughout distal section  204  up to distal tip  208 , as illustrated in  FIG.  2   . As described above, in some embodiments, distal tip  208  may also comprise sharp threads  211 . In some embodiments, sharp threads  211  on distal tip  208  are substantially identical to external threads  210 . In some embodiments, external threads  210  are helical threads. In some embodiments, external threads  210  are alternatively or additionally box threads or cutter threads. In some embodiments, the external threads  210  may have a depth of about 0.25 mm to about 2.25 mm, an angle of about 45° to about 100°, and a spacing of about 0.25 mm to about 2.25 mm. In some embodiments, external threads  210  may have a depth of about 1.0 mm, an angle of about 60°, and a spacing of about 1.75 mm. External threads  210  may vary in depth, angle, spacing, or a combination thereof throughout the body of first rod  102   a . For example, external threads  210  for distal section  204  may be coarser than those for distal tip  208 . 
     Also present, in some embodiments, is non-threaded section  212  of first rod  102   a . Non-threaded section  212  may reduce the lengths of first rod  102   a  that first knob  104   a  is threaded down. In some embodiments, proximal section  202  comprises at least a portion of non-threaded section  212  on the outer surface. In some embodiments, first rod  102   a  comprises external threads  210  along the length except for at distal tip  208 . In some embodiments, first rod  102   a  comprises no external threads  210  and the outer surface is substantially smooth. In some embodiments, the entirety of the outer surface of first rod  102   a  comprises non-threaded section  212  except for distal tip  208  which may comprise sharp threads  211  or alternative cutting means. 
     Rod  102   b  may be substantially similar in any or all aspects to rod  102   a . In some embodiments, rod  102   b  may have a different length, a different threading pattern, or a different distal tip  208  than rod  102   a.    
       FIG.  3 A  illustrates exemplary bracket  106  for certain embodiments. Bracket  106  may comprise stainless steel, steel alloys, titanium, titanium alloys, aluminum, aluminum alloys, or any combination thereof. In some embodiments, bracket  106  comprises various polymers such as acetal copolymer, polyether ether ketone (PEEK), polycarbonate, polypropylene, polyphenylsulfone, polytetrafluoroethylene (PTFE), polysulfone, polyphenylene sulfide, polyvinylidene fluoride, polyetherimide, polyphenylene oxide, or any combination thereof. In some embodiments, the material for bracket  106  is selected such that bracket  106  is radiolucent and not visible when under fluoroscopy. 
     In some embodiments, bracket  106  comprises first section  302 , second section  304 , and third section  306 , wherein third section  306  is disposed between first section  302  and second section  304 . In some embodiments, first section  302  comprises first opening  308   a  for receiving first rod  102   a  therein, and second section  304  comprises second opening  308   b  for receiving second rod  102   b  therein. Openings  308   a ,  308   b  may be substantially similar to one another. In some embodiments, openings  308   a ,  308   b  are substantially oval, stadium-shaped, circular, or rectangular. As illustrated, openings  308   a ,  308   b  may comprise first chamfer  310   a  and second chamfer  310   b , respectively. In some embodiments, chamfers  310   a ,  310   b  are substantially similar. In some embodiments, chamfers  310   a ,  310   b  are replaced with fillets having rounded edges. Openings  308   a ,  308   b  may comprise a length of about 15 mm to about 30 mm. In some embodiments, openings  308   a ,  308   b  comprise a width of about 5 mm to about 10 mm. In some embodiments, openings  308   a ,  308   b  comprise a length of about 25 mm and a width of about 8 mm. Openings  308   a ,  308   b  may be configured to substantially restrict the lateral and longitudinal movement of rods  102   a ,  102   b  and knobs  104   a ,  104   b  during use. As such, in some embodiments, there may be about 4 mm of clearance between the outer surface of first rod  102   a  and the inside walls of first chamfer  310   a  when first rod  102   a  is inserted through first opening  308   a . Second rod  102   b , second opening  308   b , and second chamfer  310   b  may be similarly sized. Rods  102   a ,  102   b  may be configured to move laterally and longitudinally within openings  308   a ,  308   b  respectively to adjust the first vertebra  110 . Knobs  104   a ,  104   b  may be sized such that they are larger than the openings  308   a ,  308   b.    
     As described above and illustrated best with respect to  FIG.  1   , in some embodiments, bracket  106  is formed such that bracket  106  is shaped to fit the shape of the patient&#39;s back when the patient is lying face down on an operating table. Third section  306  may comprise a solid section of bracket  106  connecting first section  302  and second section  304 . In some embodiments, third section  306  is about 45 mm to about 55 mm in length, or about 52 mm in length when measured from the rightmost part of first chamfer  310   a  on first section  302  to the leftmost part of second chamfer  310   b  on second section  304 . In some embodiments, third section  306  may be omitted from bracket  106  and openings  308   a ,  308   b  are combined to form a single opening in bracket  106 . 
     Bracket  106  may also comprise a first end  312   a  and a second end  312   b . First end  312   a  and second end  312   b  may be substantially identical in some embodiments. In some embodiments, ends  312   a ,  312   b  are substantially round, circular, rectangular, or trapezoidal. 
     In some embodiments, bracket  106  is positioned onto the patient such that openings  308   a ,  308   b  are substantially above first vertebra  110  during use. In some embodiments, rods  102   a ,  102   b  are inserted into the patient substantially vertically. In some embodiments, rods  102   a    102   b  are inserted into the patient at an angle of about 0° to about 30°, about 30° to about 60°, or about 60° to about 90° relative to the patient&#39;s back. During spondylolisthesis reduction, as knobs  104   a ,  104   b  are tightened and threaded down rods  102   a ,  102   b  towards the patient&#39;s back, knobs  104   a ,  104   b  may abut and press against bracket  106 , thus providing leverage for repositioning first vertebra  110  and allowing rods  102   a ,  102   b  to pull first vertebra  110  from the slipped position. 
       FIG.  3 B  illustrates a second embodiment of bracket  106 , referred to hereinafter as half bracket  314 . As described above, in some embodiments, reduction system  100  may comprise two half brackets  314  rather than the single bracket  106  illustrated in  FIGS.  1  and  3 A . In embodiments in which reduction system comprises two half brackets  314 , each of the two half brackets  314  may comprise a single opening  316  for receiving one of first rod  102   a  or second rod  102   b  therein. Opening  316  for half bracket  314  may be substantially similar to openings  308   a ,  308   b . As such, one half bracket  314  may be configured to receive first rod  102   a  therein, and a second half bracket  314  may be configured to receive second rod  102   b  therein. Each of the half brackets  314  may be placed substantially above first vertebral part  108   a  and second vertebral part  108   b , respectively. The positioning of half brackets  314  over vertebral parts  108   a ,  108   b  may be substantially similar to embodiments in which only single bracket  106  is utilized. In some embodiments, half brackets  314  comprise chamfers  318  which may be substantially similar to chamfers  310   a ,  310   b  for bracket  106 . Half bracket  314  may also comprise a first end  320   a  and a second end  320   b . In some embodiments, first end  320   a  and second end  320   b  are substantially similar. Ends  320   a ,  320   b  may be substantially round, circular, rectangular, or trapezoidal in some embodiments. 
       FIG.  4 A  illustrates exemplary first knob  104   a  for some embodiments. In some embodiments, first knob  104   a  and second knob  104   b  may be substantially similar. As described above, first knob  104   a  may be threaded down the length of first rod  102   a  towards distal section  204 . When first knob  104   a  contacts bracket  106 , continually tightening first knob  104   a  may press bracket  106  into the patient&#39;s back, and first knob  104   a  may then pull first rod  102   a , thus moving first vertebra  110 . 
     As illustrated, first knob  104   a  comprises a substantially cylindrical shape with a first face  402  and a second face  404 . In some embodiments, first face  402  is a substantially flat face and has an opposing flat face  403  on first knob  104   a . In some embodiments, second face  404  comprises a substantially cylindrical face and has an opposing cylindrical face  405  on first knob  104   a . In some embodiments, first knob  104   a  may be substantially symmetrical as best seen in  FIG.  1   . The geometry of first knob  104   a  may be configured to improve the ability of an operator to grip and thread first knob  104   a  down first rod  102   a . In some embodiments, first knob  104   a  comprises a distal end  408  and a substantially flat proximal end  407  as seen best in  FIG.  1   . Broadly, knobs  104   a ,  104   b  may take any geometrical shape such as, spherical, cylindrical, rectangular, pentagonal, hexagonal, or any combination thereof. First knob  104   a  may also comprise a textured surface on any outer surface for finger placement to aid in gripping first knob  104   a . As shown in  FIG.  4 A , the interfaces between first face  402 , second face  404 , distal end  408 , the proximal end of first knob  104   a , or any combination thereof may be chamfered or filleted to reduce the number of sharp edges present on first knob  104   a.    
     As shown, distal end  408  may comprise a substantially domed shape. In some embodiments, distal end  408  comprises a substantially flat face or cylindrical face. Distal end  408  may comprise lumen  410  extending entirely through first knob  104   a . In some embodiments, lumen  410  extends substantially through the center of first knob  104   a . Lumen  410  may be substantially cylindrical and have a diameter of about 5 mm to about 15 mm. In some embodiments, lumen  410  comprises internal threads  412  on the inner surface. In some embodiments, internal threads  412  extend throughout the entirety of the inner surface of lumen  410 . In some embodiments, internal threads  412  are configured to mate to external threads  210  on first rod  102   a . In some embodiments, internal threads  412  are omitted, and the inner surface of lumen  410  is substantially smooth. As illustrated in  FIG.  1   , distal end  408  of first knob  104   a  may be threaded towards first vertebral part  108   a . Distal end  408  may press against bracket  106  when first knob  104   a  is threaded distally down first rod  102   a . In some embodiments, first knob  104   a  may instead be flipped during operation with the flat proximal face of first knob  104   a  pressing bracket  106  when first knob  104   a  is tightened. 
     First knob  104   a  may have a length of about 25 mm to about 35 mm, or about 35 mm to about 45 mm. In some embodiments, first knob  104   a  has a length of about 35 mm. In some embodiments, first knob  104   a  is about 10 mm to about 20 mm wide from first face  402  to the opposing flat face  403 , or about 20 mm to about 50 mm wide from first face  402  to the opposing flat face  403 . In some embodiments, second face  404  and the opposing curved face  405  are about 20 mm to about 50 mm in diameter, or about 25 mm in diameter. First knob  104   a  may comprise various materials. In some embodiments, first knob  104   a  comprises different materials than first rod  102   a  to reduce the occurrence of galling between external threads  210  and internal threads  412 . First knob  104   a  may comprise a polymer, such as acetal copolymer, polyether ether ketone (PEEK), polyphenylsulfone, polytetrafluoroethylene (PTFE), polysulfone, polyphenylene sulfide, polyvinylidene fluoride, polyetherimide, polyphenylene oxide, or a combination thereof. In some embodiments, first knob  104   a  may comprise a plastic such that first knob  104   a  is radiolucent. Example plastic materials comprising first knob  104   a  include, but are not limited to, polyvinyl chloride, polycarbonate, polypropylene, polyethylene, or silicone. 
     In some embodiments, at least part of the outer surfaces of first knob  104   a  may be coated with a textured or grippable material and/or a sleeve comprising a textured or grippable material may be placed on an outer surface of first knob  104   a . For example, a silicone or rubber sleeve may be added to a portion of first knob  104   a  to enhance an operator&#39;s ability to grip first knob  104   a . In some embodiments, first knob  104   a  and/or the sleeve may further comprise various features to promote grip, such as ridges, bumps, knurling, checkered patterns, or any combination thereof. For example, first knob  104   a  may comprise a silicone sleeve covering faces  402 ,  403 ,  404 ,  405  while distal end  408  may be knurled to improve grip.  FIG.  4 B  illustrates a cross section of first knob  104   a  cut along the A-A line illustrated in  FIG.  4 A . As shown, internal threads  412  may extend throughout the length of lumen  410 , thus allowing first knob  104   a  to be threaded along the length of external threads  210 . 
       FIG.  5    illustrates an exemplary method  500  for spondylolisthesis reduction for some embodiments. The spondylolisthesis reduction may start at step  502  where the patient&#39;s spine may be accessed by the surgeon. As briefly described above, in some embodiments, spondylolisthesis reduction may be performed posteriorly with the patient lying on their stomach to allow the surgeon to access the spine posteriorly. The spine may be accessed using various techniques, such as minimally invasive techniques. In an example minimally invasive technique, a small incision may be made substantially above each of first vertebral part  108   a  and second vertebral part  108   b . In some embodiments, a single minimally invasive incision is made to access both vertebral parts  108   a ,  108   b . Once the incision has been made, a stylet or guidewire may be inserted through the incision to guide the surgeon in finding vertebral parts  108   a ,  108   b . The stylet may form an entry path, along which one or more dilators may be sequentially advanced to dilate soft tissues between the incision and first vertebra  110 . In some embodiments, a series of dilator sleeves may be placed over the guidewire, with each subsequent sleeve having a larger diameter than the previous sleeve. Once the one or more dilators have been inserted, the dilators may be removed, leaving the guidewire in place. 
     Adjacent spinal components and tissues may then be distracted using a distractor, such as a tap, that may be advanced to vertebral parts  108   a ,  108   b  following the dilation of the soft tissues. With the distractor in place in vertebral parts  108   a ,  108   b , the guidewire may be removed. At least one sleeve may then be placed over the distractor, at which point the distractor may be removed from the patient, leaving the at least one sleeve in the patient&#39;s spine. The at least one sleeve may then be used to guide the surgeon in inserting rods  102   a ,  102   b , leaving a clear pathway to vertebral parts  108   a ,  108   b . The above-described minimally invasive technique may be performed via posterior access to first vertebra  110  and via lateral access to insert the interspinous implant. As described above, various internal imaging techniques, such as fluoroscopy, may be utilized to guide the surgeon throughout the reduction process. In some embodiments, the spine is accessed via an open surgical procedure. Broadly, any method of providing access to first vertebra  110  may be used for the embodiments described herein. 
     As described above, reduction system  100  may be used to reposition first vertebra  110 , which may allow for the implantation of an interspinous implant. As such, in some embodiments, step  502  may also comprise an additional incision into the back or side of the patient to allow for the implantation of the interspinous implant. In some embodiments, the incision for inserting the interspinous implant is made after reduction system  100  is in place and first vertebra  110  has been repositioned. The above-described steps, including the guidewire, dilation, and distraction, for locating vertebral parts  108   a ,  108   b  may be followed for the additional incision as well. In some embodiments, the implant is inserted laterally. In some embodiments, rods  102   a ,  102   b  are inserted laterally and the implant is inserted posteriorly. 
     Next, at step  504 , bracket  106  or half brackets  314  may be placed onto the patient&#39;s back with openings  308   a ,  308   b  placed substantially over the incisions, providing access for rods  102   a ,  102   b  to be inserted through openings  308   a ,  308   b , into the incisions, and further into vertebral parts  108   a ,  108   b . Once in place, brackets  106 ,  314  may be secured, such as via clamps, tape, Velcro, straps, or any combination thereof, to prevent brackets  106 ,  314  from moving during the procedure. In some embodiments, brackets  106 ,  314  are secured prior to inserting rods  102   a ,  102   b  therethrough. In some embodiments, brackets  106 ,  314  are secured after rods  102   a ,  102   b  are inserted into vertebral parts  108   a ,  108   b.    
     At step  506 , rods  102   a ,  102   b  may be inserted into the patient and further into the first vertebra  110  that need repositioning. As described above spondylolisthesis may occur at the L4-L5 vertebrae; as such, rods  102   a ,  102   b  may be placed into the L4 vertebra. Alternatively, rods  102   a ,  102   b  may be placed into the L5 vertebra if the slip is present between the L5-S1 vertebrae. Rods  102   a ,  102   b  may be placed into the laminae or pedicles of first vertebra  110  or any other part of first vertebra  110  such that rods  102   a ,  102   b  can be sufficiently inserted into vertebral parts  108   a ,  108   b.    
     Rods  102   a ,  102   b  may be inserted into the patient&#39;s spine via a rotational or axial force as described above. In some embodiments, rods  102   a ,  102   b  are formed with a handle-shaped proximal end  206 . In some embodiments, rods  102   a ,  102   b  are configured to attach to various handles, such as quick connect handles. In some embodiments, knobs  104   a ,  104   b  are placed onto rods  102   a ,  102   b  before attaching the handle. Alternatively, the handle may be used to insert rods  102   a ,  102   b  into vertebral parts  108   a ,  108   b , and then the handle may be detached and knobs  104   a ,  104   b  placed onto rods  102   a ,  102   b . In some embodiments, rods  102   a ,  102   b  are rotated into vertebral parts  108   a ,  108   b  by hand. Broadly, any method of inserting rods  102   a ,  102   b  into vertebral parts  108   a ,  108   b  is contemplated for embodiments herein. 
     At step  508 , once rods  102   a ,  102   b  are in place and sufficiently attached to vertebral parts  108   a ,  108   b , the repositioning of vertebral parts  108   a ,  108   b  may begin. As described above, knobs  104   a ,  104   b  may be tightened onto rods  102   a ,  102   b . As knobs  104   a ,  104   b  are tightened, knobs  104   a ,  104   b  may contact brackets  106 ,  314 . After making contact with brackets  106 ,  314 , continually tightening knobs  104   a ,  104   b , may press bracket  106  into the patient&#39;s back and leverage brackets  106 ,  314  against the patient&#39;s back. As such, as knobs  104   a ,  104   b  are continually tightened, rods  102   a ,  102   b  may be pulled posteriorly. Consequently, because rods  102   a ,  102   b  are attached to vertebral parts  108   a ,  108   b , pulling vertebral parts  108   a ,  108   b  may move first vertebra  110 . The surgeon may then continuously adjust knobs  104   a ,  104   b  to reposition first vertebra  110  to the desired position. Tightening knobs  104   a ,  104   b  may cause first vertebra  110  to further displace posteriorly, while loosening knobs  104   a ,  104   b  may cause first vertebra  110  to displace anteriorly. In some embodiments, only one of knobs  104   a ,  104   b  needs to be tightened to reposition first vertebra  110 . For example, it may only be necessary to adjust first vertebra  110  by pulling on the right side lamina. As such, only one of rods  102   a ,  102   b  and one of knobs  104   a ,  104   b  may be utilized in reduction system  100 . 
     In an alternative embodiment, knobs  104   a ,  104   b  are omitted from reduction system  100 , such as when rods  102   a ,  102   b  are threadless. In such an embodiment, leverage may be applied to the bracket by an operator, and rods  102   a ,  102   b  may be pulled with a substantially axially force to reposition first vertebra  110 . 
     At step  510 , a spinal implant may be inserted into the spine. Reduction system  100 , with first vertebra  110  in the new position, may be held in place while the implant is inserted. In some embodiments, the interspinous implant is inserted between first vertebra  110  and second vertebra  112  and attached at the spinous processes of each first vertebra  110  and second vertebra  112 . As described above, the interspinous implant may be inserted laterally using a minimally invasive technique which may alleviate the need to dissect healthy tissue that occurs when performing open surgery. The interspinous implant may be injected with bone graft material to promote fusion. The bone graft may be either an autograft or an allograft. The volume of the bone graft material may range from about 0.5 cc to about 3.0 cc, or from 1.2 cc to about 2.5 cc, depending on the size of the interspinous implant. In some embodiments, the diameter of the interspinous implant may be about 8 mm, about 10 mm, about 12 mm, about 14 mm, or about 16 mm. In some embodiments, the interspinous implant is inserted between the two vertebrae affected by spondylolisthesis. For example, when spondylolisthesis occurs at the L4-L5 vertebrae, the implant may be inserted between the L4 and L5 vertebrae. Once implanted, the interspinous implant may work to fuse together first vertebra  110  and second vertebra  112 . 
     As detailed in the &#39;184 Patent, the entirety of which is hereby incorporated by reference, the interspinous implant may comprise an elongated body dimensioned and configured to function as a spacer for placement in a target interspinous process space. In some embodiments, the interspinous process space is the space between two adjacent spinous processes. In some embodiments, the two adjacent spinous processes are the spinous processes of first vertebra  110  and second vertebra  112 . The interspinous implant may comprise a distal anchor associated with a distal end of the implant body and a proximal anchor mounted for longitudinal movement along the body between a first position spaced apart from the head and a second position approximated with the head, adapted to compress the two adjacent spinous processes, in conjunction with the distal anchor. 
     Features described above as well as those claimed below may be combined in various ways without departing from the scope hereof. The following examples illustrate some possible, non-limiting combinations: 
     (A1) A spondylolisthesis reduction system comprising: a first bracket configured to be placed onto the back of a patient, the first bracket including at least one opening; a first rod being received through the at least one opening, the first rod having a sharpened distal end configured to be inserted into a first vertebral part of a first vertebra; and a first knob having a first lumen therethrough, the first knob receiving the first rod through the first lumen, wherein when the first knob is tightened onto the first rod, the first knob abuts the first bracket, pulls the first rod proximally, and is configured to reposition the first vertebra. 
     (A2) For the spondylolisthesis reduction system denoted as (A1), the at least one opening includes a first opening and a second opening, and wherein the first rod is received through the first opening, further including: a second rod being received through the second opening, the second rod having a sharpened distal end configured to be inserted into a second vertebral part of the first vertebra; and a second knob having a second lumen therethrough, the second knob receiving the second rod through the second lumen, wherein when the second knob is tightened onto the second rod, the second knob abuts the first bracket, pulls the second rod proximally, and is configured to reposition the first vertebra. 
     (A3) For the spondylolisthesis reduction system denoted as (A1) or (A2), the first knob includes internal threads in the first lumen and the first rod includes external threads, wherein the internal threads and the external threads cooperate together to tighten the first knob on the first rod. 
     (A4) For the spondylolisthesis reduction system denoted as (A2) or (A3), the second knob includes internal threads in the second lumen and the second rod includes external threads, wherein the internal threads and the external threads cooperate together to tighten the second knob on the second rod. 
     (A5) For the spondylolisthesis reduction system denoted as any of (A1) through (A4), the first rod has a proximal end, further including: a handle on the proximal end of the first rod, wherein the handle is configured to remain outside the patient during use and is configured to insert the sharpened distal end of the first rod into the first vertebral part when a rotational force is applied thereto. 
     (A6) For the spondylolisthesis reduction system denoted as any of (A2) through (A5), the second rod has a proximal end, further including: a handle on the proximal end of the second rod, wherein the handle is configured to remain outside the patient during use and is configured to insert the sharpened distal end of the second rod into the second vertebral part when a rotational force is applied thereto. 
     (A7) For the spondylolisthesis reduction system denoted as any of (A1) through (A6), the sharpened distal end of the first rod is removable. 
     (A8) For the spondylolisthesis reduction system denoted as any of (A2) through (A7), wherein the sharpened distal end of the second rod is removable. 
     (A9) For the spondylolisthesis reduction system denoted any of (A1) or (A3) through (A8), further including: a second bracket configured to be placed onto the back of the patient, the second bracket including at least one opening; a second rod being received through the at least one opening, the second rod having a sharpened distal end configured to be inserted into a second vertebral part of the first vertebra; a second knob having a second lumen therethrough, the second knob receiving the second rod through the second lumen, wherein when the second knob is tightened onto the second rod, the second knob abuts the second bracket, pulls the second rod proximally, and is configured to reposition the first vertebra. 
     (B1) A method for spondylolisthesis reduction in a patient comprising: providing posterior access to the spine of the patient; placing a first bracket onto the patient, the first bracket including at least one opening; providing a first rod having external threads and a sharpened distal end and a first knob having a first lumen therethrough having internal threads, inserting the first rod through the at least one opening and inserting the sharpened distal end into a first vertebral part of a first vertebra; tightening the first knob onto the external threads of first rod; and as the first knob abuts the first bracket, pulling the first rod proximally to reposition the first vertebra. 
     (B2) For the method denoted as (B1), further including: holding the repositioned first vertebra in place while an interspinous implant is inserted; and after the interspinous implant is implanted, removing the first rod from the patient. 
     (B3) For the method denoted as (B1) or (B2), wherein the at least one opening includes a first opening and a second opening, wherein the first rod is inserted into the first opening, further including: providing a second rod having external threads and a sharpened distal end and a second knob having a second lumen therethrough having internal threads, inserting the second rod through the second opening and inserting the sharpened distal end into a second vertebral part of the first vertebra; tightening the second knob onto the external threads of the second rod; and as the second knob abuts the first bracket, pulling the second rod proximally to reposition the first vertebra. 
     (B4) For the method denoted as (B3), further including: holding the repositioned first vertebra in place while an interspinous implant is inserted; and after the interspinous implant is implanted, removing the first rod and the second rod from the patient. 
     (B5) For the method denoted as any of (B1) through (B4), further including: placing a second bracket onto the patient, the second bracket including at least one opening; providing a second rod having external threads and a sharpened distal end and a second knob having a second lumen therethrough having internal threads, inserting the second rod through the at least one opening and inserting the sharpened distal end into a second vertebral part of the first vertebra; tightening the second knob onto the external threads of second rod; and as the second knob abuts the second bracket, pulling the second rod proximally to reposition the first vertebra. 
     (B6) For the method denoted as (B3) or (B5), further including: holding the repositioned first vertebra in place while an interspinous implant is inserted; and after the interspinous implant is implanted, removing the first rod and the second rod from the patient. 
     (C1) A system for spondylolisthesis reduction comprising: at least one bracket configured to be placed onto a patient substantially over at least a first vertebral part of a first vertebra; a first rod having a proximal end and a pointed distal tip; a second rod having a proximal end and a pointed distal tip; a first knob having an internally threaded lumen receiving the first rod therethrough; and a second knob having an internally threaded lumen receiving the second rod therethrough. The first rod can be inserted through the at least one bracket into the first vertebral part, the second rod can be inserted through the at least one bracket into a second vertebral part of the first vertebra, and pulling at least one of the first rod or the second rod is configured to reposition the first vertebra. 
     (C2) For the system denoted as (C1), the at least one bracket includes a first opening for receiving the first rod therethrough and a second opening for receiving the second rod therethrough. 
     (C3) For the system denoted as (C1) or (C2), the pointed distal tip of the first rod is a self-drilling tip configured to be inserted into bone. 
     (C4) For the system denoted as any of (C1) through (C3), the pointed distal tip of the second rod is a self-drilling tip configured to be inserted into bone. 
     (C5) For the system denoted as any of (C1) through (C4), the first knob has at least one flat face to facilitate gripping and wherein the second knob has at least one flat face to facilitate gripping. 
     Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the scope of the claims below. Embodiments of the invention have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to readers of this disclosure after and because of reading it. Alternative means of implementing the aforementioned can be completed without departing from the scope of the claims below. Certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations and are contemplated within the scope of the claims. Although the invention has been described with reference to the embodiments illustrated in the attached drawing figures, it is noted that equivalents may be employed, and substitutions made herein, without departing from the scope of the invention as recited in the claims.