Abstract:
A clip includes a body and a pin. The body includes a first end, a second end, and a backspan extending between the first and second ends. The backspan defines a through hole. Each of the first and second ends of the body are configured to releasably couple to a rail of a dynamic spinal clip between two adjacent segments of a dynamic spinal clip to maintain a span between two adjacent segments. The pin defines a longitudinal axis and includes a head and a shaft. The shaft extends from the head to a tip. The tip is configured to penetrate bone. The shaft is configured and dimensioned to be slidably received through the through hole of the body The head is sized to prevent the head from passing through the through hole of the body.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a device and instrument for use in orthopedic surgeries and, more specifically, to a clip that is selectively attachable to dynamic spinal plates and configured to maintain the dynamic spinal plates in an extended/expanded configuration. 
     2. Discussion of Related Art 
     The human spinal column is a highly complex structure. It includes twenty-four discrete bones, known as vertebrae, coupled sequentially to one another to house and protect critical elements of the nervous system. The cervical portion of the spine, which includes the neck of the spine up to the base of the skull, includes the first seven vertebrae. 
     For many reasons, such as aging and trauma, the intervertebral discs can begin to deteriorate and weaken. This may result in chronic pain, degenerative disc disease, or even tearing of the disc. Ultimately, the disc may deteriorate or weaken to the point of tearing and herniation, in which the inner portions of the disc protrude through the tear. A herniated disc may press against or pinch the spinal nerves, thereby causing radiating pain, numbness, and/or diminished strength or range of motion. 
     Many treatments are available to remedy these conditions, including surgical procedures in which one or more damaged intervertebral discs are removed and replaced with a prosthetic. However, should the prosthetic protrude from between the adjacent vertebrae and contact the surrounding nerves or tissues, the patient may experience additional discomfort. In procedures for remedying this problem, a spinal plate is affixed to the vertebrae and oriented to minimize such protrusion. In addition, the plate provides fixation and support to maintain spinal stability while the fusion occurs. 
     Spinal plates and cervical plates in particular, are known in the art. Fixed cervical plates generally exhibit unalterable, static dimensions. During the natural subsidence of the spinal column after surgery, the overall length of the spinal column gradually decreases. Fixed cervical plates resist this change due to their fixed axial length, which may eventually stress the spine and cause pain or discomfort. Adjustable or dynamic cervical plates attend to this predicament by providing a mechanism through which the plate is shortened to accommodate for a measure of subsidence. 
     During insertion it may be beneficial to prevent dynamic cervical plates from compressing. 
     SUMMARY 
     In an aspect of the present disclosure, a clip includes a body and a pin. The body includes a first end, a second end, and a backspan between the first and second ends. The backspan defines a through hole. Each end is configured to releasably couple to a rail of a dynamic spinal plate between adjacent segments of the dynamic spinal plate to maintain a span between the adjacent segments. The pin defines a longitudinal axis and includes a head and a shaft. The shaft extends from the head to a tip. The tip is configured to penetrate bone. The shaft is configured and dimensioned to be slidably received through the through hole of the body. The head is sized to inhibit the head from passing through the through hole of the body. The pin may include a biasing member disposed about the first portion that urges the head of the pin away from the backspan of the body. 
     In aspects of the present disclosure, the pin further includes a plate that is larger than the diameter of the through hole of the body and the backspan is disposed between the head and the plate with the first portion extending through the through hole. The second portion may include a groove and the plate may be seated within the groove. 
     In aspects of the present disclosure, the pin includes a third portion extending from the second portion along the longitudinal axis. The third portion includes a spiked end configured to engage a vertebra of a patient. 
     In aspects of the present disclosure, a kit includes a dynamic spinal plate and a clip. The dynamic spinal plate includes a first segment and a second segment moveable relative to one another between a distracted position and a compressed position. The first segment includes a pair of rails slidably received in the second segment. In the distracted position, a span is defined between the first segment and the second segment along a length of the pair of rails. The clip may be any of the clips described herein. 
     In aspects of the present disclosure, the dynamic spinal plate defines a space between two plate segments and the clip is positioned in the space. In embodiments, the space is defined within one of the first and second segments of the dynamic spinal plate. In some embodiments, the space is defined between one of the first and second segments and one of the pair of rails. The pair of rails may be adjacent an outer edge of the dynamic spinal plate. 
     In aspects of the present disclosure, the pin includes a spiked end. In a first position of the pin, the head is spaced apart from the backspan and the spiked end is between a bottom surface and a top surface of the dynamic spinal plate. In a second position of the pin, the head is in contact with the backspan and the spiked end extends beyond the bottom surface of the dynamic spinal plate. 
     In aspects of the present disclosure a method of spinal surgery includes inserting a dynamic spinal plate into a surgical site, maintaining a span between the first and second segments of the dynamic spinal plate with a clip between the first and second segments, securing the first segment to a first vertebra, securing the second segment to a second vertebra, and pulling a pin of the clip away from the surgical site to remove the clip from the dynamic spinal plate. The method may include impacting the head of the pin of the clip to partially secure the dynamic spinal plate to one of the first and second vertebrae before securing the first and second segments. The method may include aligning a drill guide with a screw hole of the dynamic spinal plate before securing the first and second segments. Aligning the drill guide may include engaging the pin of the clip with the drill guide. In embodiments, pulling the pin of the clip away from the surgical site includes engaging a backspan of the clip with a second portion of the pin. 
     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 
       Various aspects of the present disclosure are described hereinbelow with reference to the drawings, wherein: 
         FIG. 1  is a perspective view of an exemplary embodiment of a clip provided in accordance with the present disclosure; 
         FIG. 2  is a side cross-sectional view taken along the line  2 - 2  shown in  FIG. 1 ; 
         FIG. 3  is a perspective view of the clip of  FIG. 1  coupled to rails of a dynamic spinal plate; 
         FIG. 4  is a side cross-sectional view of the dynamic spinal plate taken along the line  4 - 4  shown in  FIG. 3  with the pins of the clip engaged with vertebrae of a patient; 
         FIG. 5  is a perspective view of another exemplary embodiment of a clip provided in accordance with the present disclosure coupled to a dynamic spinal plate; 
         FIG. 6  is a perspective view of additional exemplary embodiments of a clips provided in accordance with the present disclosure coupled to a dynamic spinal plate; and 
         FIG. 7  is a side view of another embodiment of a pin in accordance with the present disclosure for use with a clip. 
     
    
    
     DETAILED DESCRIPTION 
     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 used herein, the term “clinician” refers to a doctor, a nurse, or any other care provider and may include support personnel. Throughout this description, the term “proximal” will refer to the portion of the device or component thereof that is closer to the clinician and the term “distal” will refer to the portion of the device or component thereof that is farther from the clinician. In addition, the term “cephalad” is used in this application to indicate a direction toward a patient&#39;s head, whereas the term “caudad” indicates a direction toward the patient&#39;s feet. Further still, for the purposes of this application, the term “lateral” indicates 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, in the drawings and in the description that follows, 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. 
     With reference to  FIGS. 1 and 2 , an exemplary embodiment of a clip  100  is provided in accordance with the present disclosure and includes a body  110  and a pin  130 . The body  110  includes a first end  112 , a second end  114 , and a backspan  116  between the first and second ends  112 ,  114 . Each end  112 ,  114  is configured to engage rails  21  ( FIG. 3 ) of a dynamic spinal plate  10  ( FIG. 3 ) as detailed below. The backspan  116  defines a through hole  118  that is substantially centered in and orthogonal to the backspan  116 . The through hole  118  may be frustoconically shaped as best shown in  FIG. 2 . In embodiments, the through hole  118  has a substantially circular opening on the top surface of the backspan  116  and an oval opening in the lower surface of the backspan  116 . In some embodiments, the through hole  118  is cylindrical. In certain embodiments, through hole  118  defines an angle relative to the top and bottom surfaces of the dynamic spinal plate  10 . 
     The pin  130  includes a head  132 , a first portion  134 , a second portion  136 , and a spiked end  139 . The head  132  is larger than the through hole  118  such that the head  132  is inhibited from passing through the through hole  118 . The first portion  134  extends downward (as shown in  FIG. 2 ) from the head  132  and is slidably received within the through hole  118 . The second portion  136  extends downward (as shown in  FIG. 2 ) from the first portion  134 . The second portion  136  may be larger than the through hole  118  such that the second portion  136  is inhibited from passing through the through hole  118 . The spiked end  139  extends downward (as shown in  FIG. 2 ) from the second portion  136 . The head  132  and the first portion  134  may be integrally formed with one another. The pin  130  may be assembled as a two piece assembly. In embodiments, the head  132  and the first portion  134  are joined together by at least one of a friction fit, cooperating threads, welding, an eye and retaining pin, or any other known means of joining the head  132  to the first portion  134 . The first and second portions  134 ,  136  may be integrally formed with one another. In some embodiments, the first portion  134  and the second portion  136  are joined together by at least one of a friction fit, cooperating threads, welding, an eye and retaining pin, or any other suitable means. 
     With particular reference to  FIG. 2 , the pin  130  is slidably received through the through hole  118  in the backspan  116 . When the first portion  134  of the pin  130  is received within the through hole  118  of the backspan  116  of the body  110 , the head  132  of the pin  130  defines a gap G with the backspan  116  of the body  110 . The pin  130  is slidable between a first position and a second position. In the first position, the gap G has maximum dimension. In the second position, the head  132  is in contact with the backspan  116  such that the gap G has a minimum dimension. As shown, the minimum dimension of the gap G is about 0 mm and the maximum dimension of the first gap G 1  is about 15 mm; however, the maximum dimension of the gap G may be in a range of about 1 mm to about 15 mm. When the pin  130  is inserted through the through hole  118 , the pin  130  may engage a vertebra  1000  cephalad or caudad the position of the through hole  118  to partially secure the dynamic spinal plate  10  to the vertebra  1000  as detailed below. 
     Referring to  FIG. 3 , the clip  100  is engaged with rails  21  of a dynamic spinal plate  10 . The plate  10  includes a first segment  12 , a central segment  14 , and a second segment  16 . The segments  12 ,  14 ,  16  are longitudinally moveable relative to one another between a distracted position and a collapsed position. In the distracted position, the segments  12 ,  14 ,  16  are spaced apart from one another defining a span S between adjacent segments  12 ,  14 ,  16 . In the collapsed position, the segments  12 ,  14 ,  16  the span S between adjacent segments  12 ,  14 ,  16  are substantially or completely closed. It is contemplated that two adjacent segments, e.g., segments  12  and  14 , may be in a distracted position and two other adjacent segments, e.g., segments  14  and  16 , may be in a collapsed position. The segments  12 ,  14 ,  16  of the plate  10  are configured to allow adjacent segments to move towards the collapsed position and inhibit adjacent segments from moving towards the distracted position during installation and in response to subsidence of a patient&#39;s spine. Such a spinal plate is disclosed in co-owned U.S. patent application Ser. No. 12/766,438 filed Apr. 23, 2010, and Ser. No. 13/251,622 filed Oct. 3, 2011, the content of each is incorporated in its entirety. 
     The first and second ends  112 ,  114  of the clip  100  are sized and configured to selectively engage rails  21  (shown in phantom) between adjacent segments  12 ,  14 ,  16  of the plate  10  to prevent the adjacent segments  12 ,  14 ,  16  from moving towards the collapsed position, i.e., clip  100  maintains a span between adjacent segments  12 ,  14 ,  16 . It is contemplated that the body  110  may be sized to prevent adjacent segments  12 ,  14 ,  16  from additional movement towards the collapsed position after initial movement from the distracted position towards the collapsed position. 
     With reference to  FIG. 4 , at least one of the portions  134 ,  136  of the pin  130  passes through one of slots  24   a - d  in the top surface of the plate  10 . At least one of the portions  134 ,  136  of the pin  130  may pass through an opening  26  in the bottom surface of the plate  10 . When the clip  100  is engaged with plate  10  and the pin  130  is in the second position, the spiked end  139  of the pin  130  extends below the bottom surface of the plate  10  and may engage vertebrae  1000  as detailed below. When the clip  100  is engaged with the plate  10  and the pin  130  is in the first position, the end of spiked end  139  is at or above the bottom surface of the plate  10 . 
     In use, the clip  100  is installed into the span S between two adjacent segments  12 ,  14 ,  16  of the spinal plate by engaging rails  21  with ends  112 ,  114  of the clip  100  before the plate  10  is inserted into a surgical site. The clip  100  may be installed at the time of manufacturing and provided as part of a kit with the plate  10 . The clip  100  may be installed by a clinician prior to the insertion of the plate  10  into a surgical site. The pin  130  may be preloaded in the clip  100 . When the clip  100  is installed into the span S between two adjacent segments  12 ,  14 ,  16 , the plate  10  is inserted into a surgical site and aligned with vertebrae  1000  to be engaged with the plate  10 . As the plate  10  is aligned with the vertebrae  1000 , the spiked end  139  of the pin  130  may contact the vertebrae urging the pin  130  towards the first position. When the plate  10  is aligned with the vertebrae, the surgeon may impact or tap the head  132  of the pin  130  with an instrument, e.g., a hammer (not shown), to drive the spiked end  139  into the vertebra  1000  to partially secure the plate  10  to the vertebrae as shown in  FIG. 4 , similar to a center punch. The surgeon may impact the head  132  of pin  130  of multiple clips  100  to partially secure the plate  10  to the vertebrae  1000 ; in such embodiments, the pins  130  of the multiple clips  100  may engage the same or different vertebra  1000 . The surgeon may install a drill guide (not shown) on or about plate  10 . When the drill guide is installed on or about plate  10 , the drill guide is aligned with a screw hole  30  defined by the plate  10 . The drill guide may engage the head  132  or a portion  134 ,  136  of the pin  130  of a clip  100  to align the drill guide with the screw hole  30 . When the drill guide is aligned with the screw hole  30 , the surgeon utilizes the drill guide to drill a drill hole (not shown) in a vertebra through the screw hole  30 . The surgeon repeats the aligning the drill guide and drilling for each screw hole  30  of the plate  10 . In embodiments, the drill guide is rotated about the pin  130  to align the drill guide with another screw hole  30  after a drill hole is drilled. A bone screw (not shown) is then inserted into each drill hole through a respective screw hole  30  of the plate  10  to secure the plate  10  to the vertebrae. After the plate  10  is secured to the vertebrae  1000 , the head  132  of the pin  130  is engaged with a tool, e.g., needle remover, coker clamp, etc., to pull the head  132  away from the plate  10 . As the head  132  is pulled, a portion  134 ,  136  may engage the backspan  116  of the body  110  of the clip  100  to disengage the first and second ends  112 ,  114  from rails  21  of the plate  10  to remove the clip  100  from the plate  10 . After the clip  100  is removed, the adjacent segments  12 ,  14 ,  16  are free to move towards the compressed position. 
     Referring to  FIG. 5 , an exemplary embodiment of a clip  200  is provided in accordance with the present disclosure is installed in a span S on rails  22  between two adjacent segments  12 ,  14 ,  16  of a plate  10 . The clip  200  includes a body  210  and a pin  230 . The body  210  and the pin  230  of the clip  200  are substantially similar to the body  110  and the pin  130  of the clip  100  described above, as such only the differences will be detailed below. 
     First and second end portions  212 ,  214  of the body  210  include flat angular surfaces to conform to the outside surface of rails  22  (shown in phantom). A backspan  216  of the body  210  conforms to the span between rails  22 . A through hole  218  in the backspan  216  is cylindrically shaped. The first portion  234  of the pin  230  is cylindrically shaped and sized to be slidably received within the through hole  218 . A head  232  of the pin  230  is square shaped and sized to prevent the head  232  from passing through the through hole  218 , i.e., retain the first portion  234  within the through hole  218 . 
     Referring to  FIG. 6 , exemplary embodiments of a clip  300  and a clip  400  are provided in accordance with the present disclosure and are installed in respective spans between two adjacent segments  12 ,  14 ,  16  of a plate  10 . The clip  300  includes a body  310  and two pins  330 . The clip  400  includes a body  410  and a pin  430 . The body  310  and each pin  330  of the clip  300  and the body  410  and the pin  430  of clip  400  are substantially similar to the body  110  and the pin  130  of the clip  100  described above, respectively, as such only the differences will be detailed below. 
     The body  310  of the clip  300  includes a backspan  316  defining two through holes  318  near end portions  312  and  314  respectively. A pin  330  is received through each of the through holes  318  such that when a head  332  of one of the pins  330  is pulled away from the plate  10  the respective end  312 ,  314  disengages the respective rail  21 . The pin  330  passes through a spaced defined between the respective rail  21  and the segment  16  of the plate  10 . It is contemplated that when the head  332  of one of the pins  330  is pulled away from the plate  10  each end  312 ,  314  may disengage the respective rail  21 . Providing multiple pins in a clip may assist a surgeon in partially securing the plate  10  to the vertebrae before securing the plate to the vertebrae with the bone screws (not shown) as described above by providing multiple spiked ends to engage the vertebrae. In addition, providing multiple pins in a clip may assist in aligning a drill guide (not shown) with the screw holes of the plate. 
     The body  410  of the clip  400  includes a backspan  416  defining a through hole  418  adjacent one of end portions  412 ,  414 . The pin  430  passes through the through hole  418  and through a spaced defined between the respective rail  21  and segment  14  of plate  10 . The clip  400  may include a pin biasing member  433  disposed about the pin  430  between a head  432  of the pin  430  and the backspan  416  of the clip  400 . The pin biasing member  433  urges the pin  430  towards the first position as detailed above with respect to the pin  130 . When the head  432  of the pin  430  is pulled away from the plate  10 , the second end  414  disengages a respective rail  21  and then the clip  400  is manipulated to disengage the first end  412  from its respective rail  21 . 
     Referring to  FIG. 7 , another embodiment of a pin  530  in accordance with the present disclosure may be used with any of the clips  100 ,  200 ,  300 , and  400  detailed above. The pin  530  includes a pin head  532 , a first portion  534 , a plate or disc  535 , a second portion  536 , and a spiked end  539 . The pin head  532  is sized and/or shaped to prevent the pin head  532  from passing through a through hole in the backspan of the body of a clip, e.g., through hole  118  ( FIG. 1 ). The first portion  534  is sized and shaped to be slidably received through the through hole in the backspan. The plate  535  is slidably received over the first portion  534  adjacent the second portion  536 . The pin  530  may include a stop  535   a  positioned adjacent the second portion  536 . The stop  535   a  prevents the plate  535  from sliding over the second portion  536 . The stop  535   a  may seat in a groove  535   b  adjacent the junction of the first and second portions  534 ,  536 . The stop  535   a  may be a snap ring seated in the groove. In some embodiments, the plate  535  is positioned at the junction of the first and second portions  534 ,  536  and is sized and configured to prevent the second portion  536  from passing through the through hole in the backspan of the body. In particular embodiments, the plate  535  seats in a groove  535   b  at the junction of the first and second portions  534 ,  536 . The spiked end  539  is substantially similar to the spiked end  139  of the pin  130  detailed above. 
     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 and spirit of the claims appended hereto.