Patent Publication Number: US-9895181-B2

Title: Variable angle locking rotation correction plate

Description:
PRIORITY CLAIM 
     The present application is a Continuation Application of U.S. patent application Ser. No. 14/320,525 filed on Jun. 30, 2014. The entire disclosure of this patent(s)/application(s) expressly incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to bone plates for the fixation of fractures of the hand and methods of coupling these plates to bone. 
     BACKGROUND 
     Many current systems and methods for the fixation of fractures, especially fractures in the hand, are limited in the placement and orientation of plates over the bone. For example, a surgeon or other user may be required to select a final placement position of the bone plate prior to beginning a bone reduction procedure. Such plates may prevent the surgeon from selecting the most optimal implantation location for the bone plate. Furthermore, such plates may prevent the fixation of a fractured or otherwise damaged bone in a manner to fully correct the alignment of one or more bone fragments. Rather, such fragments must be brought as close to a final configuration as possible prior to the placement of the bone plate thereover, which may result in subsequent misalignment as the bone plate is being secured to the bone. Rotational misalignments are especially problematic due to crossing and scissoring of the digits when a full flexion of the fingers (e.g., making a fist) is attempted. Even minor rotational errors in the fingers may have to be surgically corrected after a fracture has healed. Furthermore, this method of insertion may also compromise adjacent soft tissue. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to A bone plate sized and shaped for fixation to one of a phalangeal and metacarpal bone, comprising a head extending from a first end to a second end and having an elongated curved plate hole extending therethrough along a curved path from a first end to a second end, a plate hole axis of the elongated curved plate hole extending orthogonally from a top surface to a bone contacting surface of the bone plate and a shaft extending from the head, the shaft including an elongated shaft plate hole extending therethrough and elongated in a direction extending orthogonal to a central longitudinal axis of the bone plate, a plate hole axis of the elongated shaft plate hole extending orthogonally from the top surface to the bone contacting surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Several embodiments of the invention will be described in the following by way of example and with reference to the accompanying drawings in which: 
         FIG. 1  shows a top view of a bone fixation plate according to a first exemplary embodiment of the invention; 
         FIG. 2  shows a bottom view of the bone fixation plate of  FIG. 1 ; 
         FIG. 3  shows a perspective view of the bone fixation plate of  FIG. 1 ; and 
         FIG. 4  shows a side view of the bone fixation plate of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     The exemplary embodiments may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The exemplary embodiments relate to apparatus and methods for the treatment of fractures and, in particular, to devices for fixing fractures of the metacarpals and phalanges. Exemplary embodiments describe a bone fixation plate having a head at a first end with an elongated shaft extending therefrom to a second end. The head of the exemplary bone plate includes first and second variable angle fixation holes along a first side thereof. The head also includes an elongated curved hole extending along a second side thereof. The elongated curved hole permits rotation and angulation of the bone plate about a cortex screw inserted therethrough as will be described in more detail below. The shaft includes third, fourth and fifth plate holes staggered about a central longitudinal axis of the bone plate and an elongated plate hole extending along an axis orthogonal to the central longitudinal axis. As will be described in greater detail later on, the elongated hole further aids in optimally positioning the plate over a target portion of the bone. The shaft further may comprise sixth and seventh variable angle locking holes at a second end thereof. The sixth and seventh holes are aligned with the central longitudinal axis. A bone contacting surface of the head has a curvature selected to conform to a curvature of a dorsal surface of a bone to ensure flush seating of the plate thereover. As will be described in greater detail later on, the exemplary curved and elongated plate holes permit the adjustment of rotation and angulation of the bone plate prior to a final fixation of the bone plate to the bone. 
     As shown in  FIGS. 1-4 , an exemplary bone plate  100  has a head  104  at a first end  102  thereof and a shaft  108  extending therefrom generally along a central longitudinal axis  110  to a second end  106 . The head  104  includes first and second variable angle plate holes  112 ,  114  extending therethrough from a bone contacting surface  116  to an upper surface  118 , the first and second plate holes  112 ,  114  being open to one another at an opening  111 . Trajectories for plate hole axes  113 ,  115  of the first and second plate holes  112 ,  114  are selected to capture common fracture patterns while avoiding the articular surface of the bone and minimizing interference with adjacent collateral ligaments. As shown in  FIG. 4 , the plate hole axes  113 ,  115  may be generally orthogonal to the top surface  118  while the variable angle feature of the plate holes  112 ,  114  permits a surgeon to vary an angle at which screws are inserted through these holes (relative to the hole axes) to optimize these trajectories to suit the anatomy of a particular patient. 
     The head  104  further comprises an elongated curved plate hole  122  extending from a first end  124  to a second end  126  along a curved arc-shaped axis  123 . A length of the plate hole  122  between the first and second ends  124 ,  126  is greater than a diameter of the first and second plate holes  112 ,  114 . A width of the plate hole  122  is equivalent to a diameter of the first and second plate holes  112 ,  114 . A length of the plate hole  122  may be equivalent to or slightly longer than a length of a combination of the first and second plate holes  112 ,  114 . The first and second plate holes  112 ,  114  and the curved plate hole  122  may be sized, shaped and positioned along the head  104  to maximize the amount of area for screw placement while minimizing the foot print of the head  104  and maintaining strength of the plate  100 . 
     A radius of curvature of the plate hole  122  may be, for example, 3.75 mm or 5.0 mm, although other values are depicted within the scope of the invention. A center from which the radius of curvature of the plate hole  122  may be measured may be located through, for example, the first plate hole  112 . The curved plate hole  122  follows a banana-like curvature, curving toward the central longitudinal axis  110  so that the first end  124  is further from the axis  110  than is the second end  126 . The exemplary curvature of the elongated curved plate hole  122  permits the bone plate to slide along the curve about a bone screw inserted therethrough. Specifically, the bone screw (not shown) may be inserted into the elongated curved plate hole  122  at a position selected to capture one or more bone fragments. The bone screw (not shown) may be inserted through the bone plate  100  and bone (not shown) to a first depth permitting the bone plate  100  to be movable about the bone screw. Subsequent sliding of the bone plate  100  along the axis  123  moves the bone plate  100  along a curved path corresponding to the path  123  as the bone plate  100  is moved in first and second directions along the central longitudinal axis  110 . Furthermore, a surgeon or other user may rotate the bone plate  100  about the bone screw (not shown) received in the elongated plate hole  122  to achieve a desired orientation over the bone, as will be described in greater detail with respect to the exemplary method below. As phalange and metacarpal fractures typically result in a breakage of the “head” or “condyle” to a smaller fragment, the curved plate hole  122  located in the head  104  permits the surgeon or other user to affix the head  104  of the plate  100  to that smaller fragment first, and then would have the ability to rotate the plate to fit the shaft. 
     An outer surface of the head  104  substantially follows a position of the first, second and elongated plate holes  112 ,  114 ,  122 . Specifically, a first side wall  128  of the head  104  follows a curved path corresponding to a curvature of the elongated plate hole  122 . A second side wall  130  of the head  104  is also curved to conform to the shape of the first and second plate holes  112 ,  114 , the size and curvature of the second wall  130  being formed so that a minimum clearance is formed about the first and second plate hole  112 ,  114 . A first notch  132  is formed on the second side wall  130  of the head  104  and has a substantially rounded shape. The first notch  132  is formed as a cutout extending into the second side wall  130  and has a shape corresponding to an arc of a circle. In another embodiment, the first notch  132  may have a non-circular shape (e.g., oblong, etc.) without deviating from the scope of the invention. The first end  102  of the bone plate  100  also comprises a second notch  134  positioned between the first and elongated plate holes  112 ,  122 , the second notch  134  also having a substantially rounded shape. In one embodiment, the second notch  134  has a radius of curvature of 1.5 mm or 2.0 mm. However, this radius of curvature is exemplary only and other values may be used without deviating from the scope of the invention. The second notch  134  is centered with respect to the central longitudinal axis  110  of the bone plate. In another embodiment, the second notch  134  may have a non-circular shape (e.g., oblong, etc.) without deviating from the scope of the invention. The first and second notches  132 ,  134  also effectively reduce an outer profile of the bone plate  100  without compromising the structural integrity thereof. 
     The bone-contacting surface  116  of the bone plate  100  is curved to conform to the curvature of a target dorsal surface of a metacarpal or phalangeal bone. In one embodiment, the bone-contacting surface  116  of the head  104  includes curvatures of varying radii. A predetermined length of the head  104  at the first corner  122  may be curved downward toward the bone in a direction toward a palmar surface of the bone in an implanted configuration. This downward curvature aids in reduction of the fracture. 
     A reduced diameter neck  136  separates the head  104  from the shaft  108 . The shaft  108  extends distally from the neck  136  to the distal end  106  and includes third, fourth, fifth, sixth and seventh variable angle plate holes  138 ,  140 ,  142 ,  144 ,  146 . In one embodiment, trajectories  139 ,  141 ,  143 ,  145 ,  147  of the third, fourth, fifth, sixth and seventh place holes  138 ,  140 ,  142 ,  144 ,  146  are orthogonal to a plane housing the bone plate  100  while the variable angle features thereof permit a surgeon to vary the angles at which screws are inserted therethrough to optimize these trajectories to suit the anatomy of a particular patient. Thus, the trajectories  139 ,  141 ,  143 ,  145 ,  147  may assume any path selected to lockingly engage the bone without extending through an opposing cortical surface thereof. The third, fourth and fifth plate holes  138 ,  140 ,  142  are staggered about the central longitudinal axis  110  so that central axes  139 ,  141 ,  143  thereof are offset relative to the axis  110 . The staggered shaft portion of the plate  100  increases plate strength and allows for distribution of bone screws over a larger surface area of the bone to capture fracture fragments in a comminuted shaft, as those skilled in the art will understand. Specifically, the third and fifth plate holes  138 ,  142  are offset in a first direction toward a first side wall  148  of the shaft  108 . Specifically, the third and fifth plate holes  138 ,  142  extend away from the axis  110  in the first direction by a distance greater than any other portion of the shaft  108 . In a preferred embodiment, the central axis  139  of the third plate hole  138  is separated from the axis  110  by a distance D 1  and the central axis  143  of the fifth plate hole  142  is separated from the axis  110  by a distance D 2 , wherein D 1  is greater than D 2 . The fourth plate hole  140  is offset in a second direction toward a second side wall  150  of the shaft  108  so that a distance D 3  is formed between a central axis  141  of the fourth plate hole  140  and the axis  110 . The distances D 2  and D 3  may be substantially equivalent to one another. The central axes  141 ,  143  of the fourth and fifth plates holes  140 ,  142 , respectively, may be closer to the axis  110  than the central axis  139  of the third plate hole  138  since the phalanges and metacarpals become thinner towards a central portion thereof. It will be understood by those of skill in the art, however, that D 1  is not required to be greater than D 2  and D 3 , so long as the third, fourth and fifth holes  138 ,  140 ,  142  are positioned through the plate  100  so that, when the plate  100  is positioned along a bone, the third, fourth and fifth holes  138 ,  140 ,  142  extend along a portion of the bone. It will also be understood by those of skill in the art that although the exemplary embodiment shows the third and fifth holes  138 ,  142  as offset from the axis  110  in the first direction towards the first side wall  148  and the fourth plate hole  140  is offset from the axis  110  in the second direction toward the second side wall  150 , a direction in which the third, fourth and fifth holes  138 ,  140 ,  142  are offset may also be reversed. In particular, the third and fifth holes  138 ,  142  may be offset in the second direction while the fourth hole  140  may be offset in the first direction. 
     The shaft  108  also includes an elongated hole  152  elongated in a direction orthogonal to the longitudinal axis  110 . The elongated hole  152  is centered about the central longitudinal axis  110 , a trajectory  153  thereof extending orthogonally from the bone contacting surface  116  to the top surface  118 . An axial length of the elongated hole  130  is at least larger than a diameter of the first through seventh plate holes  112 ,  114 ,  138 ,  140 ,  142 ,  144 ,  146  while a width of the elongated hole  152  may be equivalent to the diameter of first through seventh plate holes  112 ,  114 ,  138 ,  140 ,  142 ,  144 ,  146 . In a preferred embodiment, the first through seventh plate holes  112 ,  114 ,  138 ,  140 ,  142 ,  144 ,  146  are 1.5 mm variable angle holes. However, in another embodiment, one or more of the first through seventh plate holes  112 ,  114 ,  138 ,  140 ,  142 ,  144 ,  146  may be formed as standard locking holes having a diameter of 2.0 mm. Still further, it is noted that any other diameter of the holes may be used without deviating from the scope of the invention to conform to the requirements of a particular procedure. As will be described in greater detail below with respect to the exemplary method, the elongated hole  130  permits a surgeon or other user to slide the bone plate  100  over the bone within a predetermined range (i.e., corresponding to a length of the elongated hole  152 ) prior to locking the bone plate  100  in place. In one embodiment, the elongated hole  130  may allow for a movement of the bone plate along an axis  154  while also permitting rotation of the bone plate  100  therearound. Specifically, a surgeon or other user may insert a first bone screw into one of the elongated holes  122 ,  152  to affect a position of the bone plate  100  over the bone, as will also be described in greater detail later. The exemplary elongated plate hole  152  extends orthogonally through the bone plate from the upper surface  118  to the bone contacting surface  116 . The elongated holes  122 ,  152  bypass the need for a guidewire to position the bone plate  100  over the bone. Rather, since the bone plate  100  is adjustable relative to a bone screw inserted through the elongated hole  122 ,  152 , a surgeon or other user may use the elongated holes  122 ,  152  as a guide when positioning the bone plate  100  over the bone. 
     The sixth and seventh holes  144 ,  146  are axially aligned and symmetrically positioned relative to the central longitudinal axis  110 . 
     The bone-contacting surface  116  of the shaft  108  is curved along the longitudinal axis  110  to conform to the substantially cylindrical shape of the target portion of the bone over which the shaft  108  will be seated. In one embodiment, the length of the shaft  108  may include a single uniform curvature. In another embodiment, the bone contacting surface  116  of the shaft  108  may include a plurality of curves selected to ensure that the shaft  108  is seated flush over the bone. 
     The shaft  108  also includes a plurality of first webbed portions  158  extending along the first side wall  148  between each of the holes  138 ,  142 ,  144 ,  146  and a plurality of second webbed portions  160  extending along the second side wall  150  between each of the holes  114 ,  140 ,  152 ,  144 ,  146 . The first and second webbed portions  158 ,  160  are formed as notches extending into the width of the bone plate  100  reducing a profile thereof while maintaining the structural integrity of the bone plate  100 . The first and second webbed portions  158 ,  160  as well as the first and second notches  132 ,  134  are sized to maintain a minimum desired clearance remains around the boundary of each of the plate holes of the bone plate  100 . An outer periphery of the bone plate  100  may include a rounded taper to further reduce the profile as would be understood by those skilled in the art. 
     The bone-contacting surface  116  of the bone plate further comprises a plurality of undercuts  162 ,  164 ,  166 ,  168 ,  170 ,  172  positioned between plate holes to permit bone ingrowth while also imparting additional flexibility to the bone plate  100  to permit a surgeon to further bend the bone plate  100  to a desired curvature to more closely match the anatomy of a patient&#39;s bone and promote healthier bone ingrowth. The undercuts  162 ,  164 ,  166 ,  168 ,  170 ,  172  are formed as cutouts extending into the bone plate  100  from the bone-contacting surface  116  by a depth smaller than a thickness of the bone plate  100 . In a preferred embodiment, a shape of the cutouts is a half-cylindrical segment, although other shapes (e.g., rectangular, etc.) may be used without deviating from the scope of the invention. First, second and third undercuts  162 ,  164 ,  166  are angled with respect to the axis  110  in accordance with a position of the third, fourth and fifth plate holes  138 ,  140 ,  142 . Specifically, the first undercut  162  encloses an angle of 105° relative to the axis  110 . The second undercut  164  encloses an angle of 60° relative to the axis  110 . The third undercut  166  encloses an angle of 120° relative to the axis  110 . Fourth, fifth and sixth undercuts  168 ,  170 ,  172  extend orthogonally to the axis  110 . 
     The exemplary bone plate  100  is configured for use in indirect reduction techniques for crushes, multi-fragmented and/or periarticular fractures of the metacarpals and phalanges. In accordance with an exemplary method according to the invention, the bone plate  100  is positioned over a target dorsal surface of a bone in a target orientation so that the elongated curved plate hole  122  is positioned adjacent a far side of a fracture near a section of intact bone. The surgeon or other user approximates the desired position of the bone plate  100  over the bone. A first cortex screw (not shown) is then inserted through the elongated curved hole  122  and into the bone to a first depth sufficient to hold the bone plate  100  over the bone while still permitting movement of the bone plate  100  relative to the bone The bone plate  100  is then slid along the axis  123  about the first cortex screw (not shown) received in the hole  122  until a desired position has been reached. The first cortex screw (not shown) may be tightened and loosened a plurality of times during this repositioning. A second cortex screw (not shown) is then inserted into the elongated hole  152  to the first depth sufficient to hold the bone plate  100  over the bone while still permitting movement of the bone plate  100  relative to the bone. The bone plate  100  is then repositioned along the axis  154  to a desired final configuration. The first and second cortex screw (not shown) may be tightened and loosened a plurality of times during the above repositioning. The exemplary bone plate  100  according to the invention allows for an adjustment of rotation and angulation of the bone plate  100  prior to a permanent fixation thereof over the bone. Once the target position has been reached, additional screws (not shown) may be inserted into any of the remaining plate holes  112 ,  114 ,  138 ,  140 ,  142 ,  144 ,  146 . The exemplary system and method according to the invention bypasses the need for pre-drilling holes in the bone. Rather, once the target position has been achieved, bore holes are drilled through any of the plate holes  112 ,  114 ,  138 ,  140 ,  142 ,  144 ,  146  and into the bone at a desired angle selected to conform to the requirements of the particular bone. In contrast, present bone fixation systems require the insertion of a guidewire into the bone prior to the placement of the bone plate over the bone, thus requiring that a final position of the bone plate  100  be selected prior to the placement of the bone plate over the bone. This method may lead to reduced accuracy in placement, especially in the fixation of phalangeal bones where even the smallest deviation, (e.g., in millimeters) from a correct position may lead to less than optimum fixation. The exemplary bone plate  100 , on the other hand, permits adjustment of the position of the bone plate  100  even after the bone plate  100  has been initially secured to the bone, thereby ensuring that the final position of the bone plate  100  captures all fragments of the bone while avoiding interference with ligaments, tendons or other tissue. 
     It will be appreciated by those skilled in the art that various modifications and alterations of the disclosed embodiments may be made without departing from the broad scope of the invention. Some of these have been discussed above and others will be apparent to those skilled in the art.