Abstract:
A spinal rod includes a central connector and first and second legs. The central connector has first and second ends. The first leg has first, second, and third sections. The first section of the first leg is directly coupled to the first end of the central connector. The second leg has first, second, and third sections. The first section of the second leg is directly coupled to the second end of the central connector. The second leg is spaced apart from the first leg to define a gap therebetween. The spinal rod defines a longitudinal axis and each of the second sections is parallel to the longitudinal axis in first and second planes that are orthogonal to one another. The first plane passes through each of the second sections which are each offset from the longitudinal axis. The second plane passes through the central connector and bisects the spinal rod.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of, and priority to, U.S. Provisional Patent Application Ser. No. 62/008,014, filed on Jun. 5, 2014, entire contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates to methods, systems, and apparatus for bony fixation and, more specifically, to methods, systems, and apparatus adapted for fixing the bones of the spine. 
         [0004]    2. Discussion of Related Art 
         [0005]    The human spine is comprised of thirty-three vertebrae and twenty-four as an adult. An infant contains 7 cervical vertebrae, 12 dorsal or thoracic vertebrae, 5 lumbar vertebrae, 5 sacral vertebrae, and 4 coccygeal or caudal vertebrae. In an adult, the 5 sacral vertebrae fuse together to form the sacrum and the 4 coccygeal vertebrae fuse to form the coccyx. Intervertebral discs lie between each pair of adjacent vertebrae. Every intervertebral disc maintains a space between adjacent vertebrae and acts as cushion under compressive, bending, and rotational loads and motions. Each intervertebral disc has a fibrocartilaginous central portion called the nucleus pulposus. The nucleus pulposus of a healthy intervertebral disc contains significant amount of water. This water content provides spongy quality and allows it to absorb spinal stress. 
         [0006]    Each intervertebral disc has an annulus fibrosus, which condition might be affected by the water content of the nucleus pulposus. The annulus fibrosus consist of a ring of fibrocartilage and fibrous tissue forming the circumference of the intervertebral disc. Excessive pressure or injuries to the intervertebral discs may adversely affect the annulus fibrosus. Usually, the annulus fibrosus is the first portion of the intervertebral discs that is injured. The annulus fibrosus may be injured in several ways. Typically, the annulus fibrosus tears due to an injury. When these tears heal, scar tissue forms in the annulus fibrosus. Given that scar tissue is not as strong as normal ligament tissue, the annulus becomes weaker as more scar tissue forms. An annulus fibrosus with scar tissue is usually weaker than a normal annulus fibrosus. The formation of scar tissue may eventually lead to damage of the nucleus pulposus. As a result of this damage, the nucleus fibrosus may, for instance, lose water content, hindering the intervertebral disc&#39;s ability to act as a cushion. The reduced cushioning capability might increase stresses on the annulus fibrosus and, consequently, cause still more tears. Hence, the annulus fibrosus may undergo a degenerative cycle consisting of exponential reduction of water content. Eventually, the nucleus pulposus may lose all its water. As the nucleus pulposus loses its water content, it collapses and thus allows the vertebrae above and below the disc space to move closer to each other. In other words, the intervertebral disc space narrows as the nucleus pulposus loses water. When the nucleus pulposus collapses, the facet joints, which are located on the back of the spine, shift, altering the way these joints work together. 
         [0007]    When a disc or vertebra is damaged due to disease or injury, performing a spinal fusion is one of the techniques used for treating the patient. During spinal fusion, a surgeon removes part or all of the intervertebral disc, inserts a natural or artificial disc spacer, and constructs an artificial structure to hold the affected vertebrae in place. While the spinal fusion may address the diseased or injured anatomy, the natural biomechanics of the spine are affected in a unique and unpredictable way. 
       SUMMARY 
       [0008]    In an aspect of the present disclosure, a spinal rod includes a central connector, a first leg, and a second leg. The central connector has first and second ends. The first leg has first, second, and third sections. The first section of the first leg is directly coupled to the first end of the central connector. The second leg has first, second, and third sections. The first section of the second leg is directly coupled to the second end of the central connector. The second leg is spaced apart from the first leg to define a gap therebetween. The spinal rod defines a longitudinal axis and each of the second sections is parallel to the longitudinal axis in first and second planes that are orthogonal to one another. The first plane passes through each of the second sections which are each offset from the longitudinal axis. The second plane passes through the central connector and bisects the spinal rod. The central connector and the first and second legs may be of unitary construction or may be monolithically formed with one another. 
         [0009]    In aspects, the first and second legs are identical to one another when viewed perpendicular to the second plane. Each of the first sections may be curved relative to the first plane and parallel to the second plane. Each of the first sections may include a first curve adjacent the central connector and a second curve adjacent the second section of the respective first and second legs. 
         [0010]    In some aspects, each of the third sections is curved relative to the first and second planes. Each of the third sections may have a first end adjacent the second section of the respective one of the first and second legs. Each of the third sections may have a second end that is spaced apart from the second section of the respective one of the first and second legs. Each of the third sections may be curved away from the first and second planes from the first end to the second end. 
         [0011]    In certain aspects, the central connector is parallel to the first plane. The central connector may be semi-circular. 
         [0012]    In particular aspects, the first and second legs are configured to conform to a curvature of a spinal column. A curvature of the first section of the first and second legs may conform to a curvature of a thoracic region of the spinal column and a curvature of each of the third sections is configured to conform to a curvature of a lumbar region of the spinal column. 
         [0013]    In an aspect of the present disclosure, a spinal rod includes a central connector, a first leg, and a second leg. The central connector has an arcuate configuration and includes first and second ends. The central connector is located in a first plane. The first leg has first, second, and third sections. The first section of the first leg is attached to the first end of the central connector and is monolithically formed therewith. The second leg has first, second, and third sections. The first section of the second leg is attached to the second end of the central connector and is monolithically formed therewith. The second sections are parallel to each other and are disposed in a second plane that is parallel to the first plane and is spaced therefrom. The first and second legs define a gap therebetween such that a distance between the first sections of the first and second legs is equal to a distance between the second sections of the first and second legs. 
         [0014]    In an aspect of the present disclosure, a spinal rod includes a central connector, a first leg, and a second leg. The central connector has a first and second ends and is semi-circular therebetween. The first leg has first, second, and third sections. The first section of the first leg is unitarily formed with the first end of the central connector. The second leg has first, second, and third sections. The first section of the second leg is unitarily formed with the second end of the central connector. The second sections of the first and second legs are parallel to a longitudinal axis defined by the spinal rod in first and second planes that are orthogonal to one another. The first plane passes through the second sections of the first and second legs. The second plane passes through the central connector to bisect the spinal rod. The central connector is parallel to the first plane. The first section of each of the first and second legs is curved relative to the first plane and conformable to a curvature of a thoracic region of a spinal column and parallel to the second plane. The third section of each of the first and second legs is curved relative to the first and second planes and is conformable to a curvature of a lumbar region of the spinal column. 
         [0015]    In another aspect of the present disclosure, a method of fixing a spinal column includes securing a first pair of pedicle screws in a first vertebra in a thoracic region of the spinal column and a second pair of pedicle screws in a second vertebra in a lumbar region of a spinal column and securing a first section of first and second legs of a spinal rod to heads of the first pair of pedicle screws, and securing a third section of the first and second legs to heads of the second pair of pedicle screws. One of each pair of the pedicle screws is positioned on one side of a spinal process of a respective vertebra and a second one of each pair of pedicle screws positioned on the other side of the spinal process of the respective vertebra. A central connect extending cephaladly from an end of each of the first and second legs and another end of each of the first and second legs extend caudally from the heads of the second pair of pedicle screws. 
         [0016]    In aspects, the method includes conforming the rod to the thoracic region of the spinal column. Conforming the rod to the thoracic region of the spinal column may include adjusting a curvature of the first sections of the first and second legs. 
         [0017]    In some aspects, the method includes conforming the rod to the lumbar region of the spinal column. Conforming the rod to the lumbar region of the spinal column may include adjusting a curvature of second sections of the first and second legs. 
         [0018]    Further, to the extent consistent, any of the aspects described herein may be used in conjunction with any or all of the other aspects described herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Various aspects of the present disclosure are described hereinbelow with reference to the drawings, which are incorporated in and constitute a part of this specification, wherein: 
           [0020]      FIG. 1  is a posterior plan view of a spinal rod in accordance with the present disclosure fixed to a spinal column of a patient; 
           [0021]      FIG. 2  is a side profile view of the spinal rod fixed to the spinal column of the patient of  FIG. 1 ; 
           [0022]      FIG. 3  is a posterior plan view of the spinal rod of  FIG. 1 ; and 
           [0023]      FIG. 4  is a side profile view of the spinal rod of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    Embodiments of the present disclosure are now described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. As commonly known, the term “clinician” refers to a doctor, a nurse or any other care provider and may include support personnel. Additionally, the term “proximal” refers to the portion of the device or component thereof that is closer to the clinician and the term “distal” refers to the portion of the device or component thereof that is farther from the clinician. In addition, the term “cephalad” is known to indicate a direction toward a patient&#39;s head, whereas the term “caudal” indicates a direction toward the patient&#39;s feet. Further still, the term “lateral” is understood to indicate a direction toward a side of the body of the patient, i.e., away from the middle of the body of the patient. The term “posterior” indicates a direction toward the patient&#39;s back, and the term “anterior” indicates a direction toward the patient&#39;s front. Additionally, terms such as front, rear, upper, lower, top, bottom, and similar directional terms are used simply for convenience of description and are not intended to limit the disclosure. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. 
         [0025]    Referring now to  FIGS. 1 and 2 , a bilateral contoured rod  10  is provided in accordance with the present disclosure and is secured to a spinal column  100  of a patient. The rod  10  is secured to the spinal column  100  by a plurality of pedicle screws  110  fixed to vertebra of the spinal column  100  on both sides of spinal processes of the spinal column  100 . As shown, the rod  10  is secured to the posterior side of the spinal column  100 . To secure the rod  10  to each of the pedicle screws  110 , the rod  10  is received within a head  120  of each pedicle screw  110 . As shown, the rod  10  is secured to the heads  120  of the pedicle screw  110  with a tulip or taper-locking head. It is contemplated that the rod  10  may also be secured to the heads  120  by a set screw (not shown). Examples of pedicle screws with taper-locking heads are disclosed in U.S. Pat. No. 8,814,919 and examples of pedicle screws with rods secured by set screws are disclosed in U.S. Pat. No. 8,403,971, the entire contents of each of these disclosures hereby incorporated by reference. 
         [0026]    With reference to  FIGS. 3 and 4 , the rod  10  includes a central connector or cephalad connector  12 , a first leg  14 , and a second leg  16 . Each leg  14 ,  16  extends from a first or cephalad section  20  that is monolithically formed with the cephalad connector  12 , through a second or central section  30 , and to a third or caudad section  40 . With particular reference to  FIG. 3 , the rod  10  is monolithically formed or is of unitary construction from a first end  15  of the rod  10  in the caudad section  40  of the first leg  14  to a second end  19  of the rod  10  in the caudad section  40  of the second leg  16 . The rod  10  extends from the first end  15  at an end of the first leg  14  to the cephalad connector  12  and extends from the cephalad connector  12  the second end  19  at an end of the second leg  16 . 
         [0027]    With particular reference to  FIGS. 2 and 4 , the first and second legs  14 ,  16  are substantially similar in a side profile such that the rod  10  is sized and shaped to conform to or to define a curvature of a spinal column. Additionally or alternatively, the rod  10  is conformable to accommodate differences between patients. Specifically, the cephalad sections  20  are curved in a sagittal plane of a patient between the cephalad connector  12  and the central section  30  to conform to a thoracic region of a spinal column and the caudad sections  40  are curved in a sagittal plane and a coronal plane of a patient from the central section to the ends  15 ,  19  of the rod  10  to conform to a lumbar region of a spinal column. The central section  30  is substantially linear and parallel to a central longitudinal axis A-A of the rod  10 . 
         [0028]    A center of curvature  22  of the cephalad section  20  in a sagittal plane of a patient is above the central section  30  as shown in  FIG. 4  and a center of curvature  42  of the caudad section  40  in the sagittal plane is below the central section as shown in  FIG. 4 . The caudad section  40  also has a center of curvature  44  in the coronal plane as shown in  FIG. 3 . It is contemplated that the center of curvature  42  and the center of curvature  44  may be the same or different points. The cephalad section  20  may include a transitional curvature  24  to transition into the cephalad connector  12 . The transitional curvature  24  may have a radius of about 0.5 inches in a direction opposite the curvature of remainder of the cephalad section  20 . 
         [0029]    The central sections  30  define a central plane that passes through the central longitudinal axis A-A and each of the central sections  30 . The central plane is configured to be parallel to a coronal plane of a patient. The cephalad connector  12  is substantially linear in the side profile and parallel to the central sections  30 . The cephalad connector  12  is offset from the central longitudinal axis A-A and the central plane by a distance D 1 . The distance D 1  is in a range of about 0.8 inches to about 1.6 inches. 
         [0030]    With particular reference to  FIG. 3 , the first and second legs  14 ,  16  are offset from the central longitudinal axis A-A of the rod  10  to define a gap therebetween. The gap is substantially constant between the cephalad and central sections  20 ,  30  and increases between the caudad sections  40  reaching a maximum gap at the first and second ends  15 ,  19 . Between the cephalad and central sections  20 ,  30  the gap has a distance D 2  and between the ends  15 ,  19  the gap has a distance D 3 . The distance D 2  is in a range of about 0.750 to about 1.250 inches (e.g., about 1.000 inches). The distance D 3  is in a range of about 2.200 to about 3.200 inches (e.g., about 2.585 inches). The gap may increase as defined by a radius of curvature in a coronal plane of a patient. 
         [0031]    The cephalad connector  12  has first and second ends  11 ,  13  and is arcuate therebetween. The cephalad connector  12  is in a plane parallel to the central plane. The first end  11  is connected to the cephalad section  20  of the first leg  14  and the second end  13  is connected to the cephalad section  20  of the second leg  16 . The cephalad connector  12  is configured to wrap around a spinal process of a vertebra. As shown, the cephalad connector  12  defines a uniform semi-circular curve; however, it is contemplated that the cephalad connector  12  may include two corners and a backspan, a non-uniform curve, or any other structure for passing around or through a spinal process of a spinal column to connect the first and section legs  14 ,  16  together. 
         [0032]    With reference to  FIGS. 1 and 2 , to install the rod  10  onto the spinal column of a patient, two pedicle screws  110  ( FIG. 1 ) are secured in each vertebrae of the spinal column  100  on either side of the spinal processes for the regions to be secured to the rod  10  (e.g., vertebra in the thoracic and lumbar regions of the spinal column). A rod  10  is selected that defines a desired curvature of the spinal column of the patient (i.e., the first curvature selected to define the curvature of the thoracic region of the spinal column of the patient and the second curvature selected to define the curvature of the lumbar region of the spinal column). The rod  10  is then fixed to the head  120  of each pedicle screw  110  using known methods including, but not limited to, using a set screw or a tulip head. A rod reducer (not shown) may be used to position the rod  10  in the head of each pedicle screw  110 . 
         [0033]    It is contemplated that a rod  10  may be selected or adjusted to conform or fit to a spinal column of a patient. Specifically, cephalad sections  20  of the rod  10  may be selected or adjusted to conform or fit a curvature of a spine of a patient in a sagittal plane of a patient. In addition, the caudal sections  40  may be selected or adjusted to conform or fit a curvature of a spine of a patient in a sagittal plane and/or a coronal plane of a patient. The caudal section  40  may conform or fit a lumbar section of the spine of a patient. It is also contemplated that the caudal section  40  may extend into a sacral region of the spine of the patient. The caudal section  40  may be selected and/or adjusted to conform with a curvature of the spine of a patient in the sagittal plane and then separately selected or adjusted to conform with a curvature of the spine of the patient in the coronal plane of a patient (e.g., to fit around spinal processes of a lumbar and a sacral region of a patient). 
         [0034]    While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Any combination of the above embodiments is also envisioned and is within the scope of the appended claims. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope of the claims appended hereto.