Bone plate

Notice: More than one reissue application has been filed for the reissue of U.S. Pat. No. 9,974,583.

The present application is(a) a Reissue Continuation application of U.S. patent application Ser. No. 16/696,282 filed on Nov. 26, 2019, which issued on Jan. 2, 2024 as U.S. Pat. No. RE49,771; which is an application for Reissue of U.S. patent application Ser. No. 15/722,775 filed on Oct. 2, 2017, which issued on May 22, 2018 as U.S. Pat. No. 9,974,583; which isa Continuation Application of U.S. patent application Ser. No. 13/100,784 filed on May 4, 2011, now U.S. Pat. No. 9,801,669; which claims priority to U.S. Provisional Application Ser. No. 61/350,691 filed on Jun. 2, 2010; and (b) the present application is an application for Reissue of U.S. patent application Ser. No. 15/722,775 filed on Oct. 2, 2017, which issued on May 22, 2018 as U.S. Pat. No. 9,974,583. The disclosure of the above patent(s)/application(s) is incorporated herein by reference.

The present invention generally relates to a bone plate which can be fixed to a bone by means of bone screws. More particularly, the present invention relates to a bone plate having a through hole with an internal thread to threadably receive a locking bone screw.

Bone plates with through holes comprising a cylindrical or conical interior thread to receive a locking head bone screw are commonly used in the field of osteosynthesis. Due to the threaded connection between the head of the bone screw and the through hole in the bone plate the bone screw is firmly anchored in the through hole in the bone plate. However, one problem that can arise is that if the bone screw is not exactly coaxially inserted with respect to the through hole axis the thread of the through hole can be damaged.

The present invention relates to a bone plate being able to receive at least a central bone screw in such a way that the thread in the through hole in the bone plate is not damaged when a bone screw is inserted.

According to the present invention, described is a bone plate with a proximal surface, a bone-oriented distal surface and a through hole the wall of which has three or more straight or convex sections provided with projections such as thread or thread-like structures for receiving a screw head of a bone screw.

One of the advantages of the bone plate according to the present invention include a compact entry for setting at choice bone screws under a variable angle is provided in such a way that the thread in the through hole in the bone plate is not damaged when a bone screw is not coaxially inserted with respect to the longitudinal axis of the through hole. Furthermore, due to the configuration of a through hole with three or more straight or convex sections, a bone screw inserted through the through hole may be angled relative to a longitudinal axis of the through hole with a reduction of damage to the threads of the through hole.

In an exemplary embodiment of the bone plate, the through hole has a cross-sectional area orthogonal to the longitudinal axis with a center of the cross-sectional area being centered on the longitudinal axis and wherein each of the three or more straight or convex sections is limited by two radii intersecting each other in the center and enclosing an angle Ω which is smaller than or equal to 360°/n (where n is the number of straight or convex sections), as will be described in greater detail below.

In a further exemplary embodiment of the bone plate, the through hole has a cross-sectional area orthogonal to the longitudinal axis which is generally polygonal, preferably with rounded corners.

In a further embodiment of the bone plate, the through hole tapers in a direction towards a distal surface of the bone plate.

In again a further embodiment of the bone plate, the three or more straight or convex sections are radially symmetric.

In another embodiment of the bone plate, a thread or thread-like structure extends over the whole length of the three or more straight or convex sections.

In another embodiment of the bone plate, the thread or thread-like structure has a constant depth of thread within the straight or convex sections.

In yet another embodiment of the bone plate the depth of thread of the thread or thread-like structure decreases towards each end of each of the straight or convex sections.

In still another embodiment of the bone plate the depth of thread of the thread or thread-like structure decreases outside each end of each of the straight or convex sections.

In again another embodiment of the bone plate, the thread or thread-like structure extends over the whole periphery of the through hole.

In a further embodiment of the bone plate according to the present invention, the bone plate comprises two or more peripheral holes connected to and open to a through hole. The peripheral holes include a thread for receiving peripheral bone screws therein. The two or more peripheral holes are arranged peripherally around the through hole in such a way that they overlap with the through hole to form a composite hole structure able to receive two or more peripheral bone screws therein while a central bone screw is received in the through hole.

In a further embodiment of the bone plate each of the peripheral holes comprises a spherical recess penetrating partially into the bone plate from a proximal surface thereof. The advantage of this configuration is that a conventional cortex screw with an unthreaded spherical head may be introduced into such a peripheral hole at an angle relative to the longitudinal axis selected by the user.

In a further embodiment of the bone plate according to the invention, each of the peripheral holes and the through hole includes a thread for locking the screw received therein at a fixed angle.

In another embodiment of the bone plate, the peripheral holes include threading for receiving peripheral bone screws at user selected variable angles relative to the longitudinal axes of these peripheral holes while the through hole is configured to receive a central bone screw at a fixed angle.

In a further embodiment of the bone plate, the threads of the holes extend over at least half of a circumference of each of the holes.

In still a further embodiment of the bone plate, a number, N, of holes are arranged at the corners of a central through hole being generally polygonal with N corners. The polygon defined by the hole axes of the N holes, when viewed in a cross-section orthogonal to the longitudinal axis of the through hole, can be a triangle, square, pentagon or hexagon.

In another embodiment of the bone plate the fixed angle of insertion of bone screws through the peripheral holes is in the range of ±0° to ±20°, preferably of ±8° to ±15° with respect to the longitudinal axis.

In yet another embodiment of the bone plate the pitch of the threads is in the range of 0.30 to 2.00 mm, preferably in the range of 0.5 to 1.0 mm.

In again another embodiment of the bone plate the threads are multiple threads. This allows the advantage that the pitch matches the bone thread pitch.

In still another embodiment of the bone plate the centers of two adjacent holes are at a distance of 4 to 15 mm from each other.

In a further embodiment of the bone plate the diameter of the holes is in the range of 3 to 10 mm.

In again a further embodiment of the bone plate, an inscribed circle to the wall of the central through hole has a diameter of 2 to 10 mm, preferably of 3 to 7 mm.

In another embodiment according to the present invention, the bone plate comprises at least one peripheral bone screw wherein the plate is made of stainless steel and the at last one peripheral bone screw is made of a CoCr alloy or vice versa. Thus, the advantage can be achieved that since the threads are less damaged by the plate according to the invention there is also less corrosion between plate and screws.

In again another embodiment of the bone plate a hole axis of the at least one hole is not parallel to the longitudinal axis of the though hole and preferably angled relative thereto at an angle of ±5° to ±20°.

In again another embodiment the bone plate comprises more than one through hole.

In again another embodiment of the bone plate, the wall of the through hole has n=3 straight or convex sections.

In a further embodiment a bone plate is provided with a proximal surface, a bone-oriented distal surface and a through hole with a longitudinal axis connecting the proximal and distal surfaces, wherein the wall of the through hole has n≥3 non-concave sections provided with a thread or thread-like structures for receiving a screw head of a bone screw.

According to a further object of the invention a kit for bone fixation is provided comprising a bone plate according to the invention, a central bone screw and N peripheral bone screws.

In a special embodiment of the kit, the central bone screw comprises a screw head with an external thread matching the thread or thread-like structure in the through hole of the bone plate and the N peripheral bone screws comprise a screw head each with an external thread matching the thread in the N≥2 holes.

In another embodiment of the kit, the screw head of the central bone screw is conically or spherically shaped and the screw heads of the peripheral bone screws are conically or spherically shaped.

a central bone screw with a conically shaped threaded screw head that is placed at fixed angle relative to the bone plate; a central bone screw with a spherically shaped threaded screw head that can be placed at a variable angle relative to the bone plate; N peripheral bone screws with a conically shaped threaded screw head that are placed at a fixed angle relative to the bone plate; or N peripheral bone screws with a spherically shaped threaded screw head that are placed at a variable angle relative to the bone plate. In again another embodiment the kit comprises more than one central bone screws with differently shaped screw heads and a number of 2×N peripheral bone screws with differently shaped screw heads. This configuration allows the advantage that the surgeon can select between:

In a further embodiment the kit comprises a bone plate, a central bone screw with a screw head that is conically or spherically shaped and comprises an external thread and N conventional cortex screws as peripheral bone screws.

The present invention is directed to a system for the fixation of fractured or otherwise damaged bones via one or both of a variable angle insertion and a fixed angle insertion of a bone screw through a bone plate hole. Specifically, a bone plate according to the present invention is provided with a central through hole configured to receive a first bone screw therethrough at any user selected angle relative to a longitudinal axis of the through hole within a permitted range of angulation. A plurality of second bone screws may also be inserted through outlying portions of the bone plate hole, each defining a separate plate hole axis. The outlying portions of the bone plate hole are formed as substantially circular peripheral holes configured to overlap and be open to the through hole to form a composite hole having any of a plurality of shapes depending on the placement and number of the peripheral holes relative to the through hole, as will be discussed in greater detail with respect to particular embodiments. The peripheral holes may be configured with holes axes selected so that the second bone screws may only be inserted therethrough at predetermined angles relative to a surface of the bone plate. It is noted that although the peripheral holes and through holes are depicted with predetermined angles in the system of the present invention, these bone plate holes may extend through the bone plate at any angle without deviating from the spirit and scope of the present invention and may be selected to conform to the requirement of a particular procedure.

1 8 FIGS.to 1 FIG. 1 9 2 9 9 9 1 7 8 9 6 7 8 6 7 9 10 15 5 30 15 15 15 illustrate a first exemplary embodiment of the invention comprising a bone plateincluding one through holeand three partially cylindrical peripheral holesarranged peripherally around the through holein such a way that they overlap with the through holeand are open thereto, as will be described in greater detail below. It is noted that although the through holeis depicted with a triangular cross-sectional shape, any other cross-sectional shape may be employed without deviating from the spirit and scope of the present invention. The bone platecomprises a proximal surfaceand a bone-oriented distal surface. The through holehas a longitudinal axisconnecting the proximal and distal surfaces,, the longitudinal axisextending orthogonally to the proximal surface. The through holeis at least partially bordered by a wallincluding three convex sectionsprovided with projections such as a threador thread-like structures for receiving a central bone screwunder a variable angle. As will be described in greater detail later, each of the three convex sectionsofis curved with a predetermined radius of curvature. In an alternate embodiment (not shown), any number and combination of the convex sectionsmay be formed with a first radius of curvature while the remainder of the convex sectionsmay be formed with a second radius of curvature.

2 11 7 8 4 20 2 9 2 11 2 6 9 2 9 2 9 20 30 2 4 6 8 FIGS.- 5 8 FIGS.to 2 4 FIGS.to 5 FIG. Each of the peripheral holeseach has a hole axisextending between the proximal and distal surfaces,and are provided with a threadfor receiving peripheral bone screws, as shown in. The peripheral holesare arranged peripherally around the through holeat equal angles relative to each other. In the embodiment shown where three peripheral holesare employed, the axesof the peripheral holes, when viewed in a cross-section orthogonal to the longitudinal axisof the through hole, define an equilateral triangle. Furthermore, the three peripheral holesoverlap the through holein such a way that the peripheral holesand through holeform a composite hole structure suitable to receive 3 peripheral bone screws, as shown inand/or one central bone screw, as shown in. As shown in, the peripheral holeseach also comprise a thread, which, in one embodiment of the present invention, may be a multiple thread.

6 9 15 15 7 9 15 9 30 9 33 30 6 9 9 30 20 2 When viewed in a cross-section orthogonal to the longitudinal axisof the through hole, each of the convex sectionsis centrally positioned along a respective corner of an equilateral triangle. Each convex sectionis convexly curved in a direction from the proximal surfaceto the distal surfaceso that an apex of each of the convex sectionsis located radially outside the through hole. A bone screwcan be inserted into the through holeunder a surgeon selected angle so that a screw axisof the bone screwis offset by an angle α relative to the longitudinal axisof the through hole. The through holeof the present invention may be configured so that the bone screwinsertable therethrough is smaller, larger or the same size as the bone screwsinsertable through the peripheral holes.

15 2 11 2 6 2 9 9 10 9 2 2 15 5 15 5 15 2 The composite hole structure therefore includes three radially symmetrically arranged convex sectionscentrally located on the sides of an equilateral triangle and three peripheral holesin the corners of the equilateral triangle. The axesof the peripheral holesare arranged at a distance from the longitudinal axiswhich is dimensioned in such a way that the peripheral holesoverlap the through holeand extend over an angle of more than 180° between their transitions to the through hole. The wallof the through holecomprises n=3 wall portions with each wall portion being limited by a transition to the periphery of a first peripheral holeat one of its ends and by a transition to the periphery of a second peripheral holeat its other end. In the present embodiment each convex sectiondoes not extend over the whole length of the wall portion limited by the transitions. The threador thread-like structure extends over the whole length of the three convex sectionswith a constant depth of thread. The depth of thread of the threador thread-like structure decreases between each end of the convex sectionand each of the two transitions to one of the peripheral holes.

2 4 FIGS.to 9 8 1 30 33 31 9 31 32 30 33 6 9 As illustrated inthe through holetapers radially inward toward the distal surfaceof the bone plate. A central bone screwwith a screw axisand a screw headis inserted in the through hole. The screw headis spherically shaped and comprises an external threadso that the central bone screwcan be inserted into the through hole at a user-selected angle α between the screw axisand the longitudinal axisof the through hole.

30 31 32 9 9 6 9 Instead of a central bone screwcomprising a spherically shaped screw headwith an external threada central bone screw comprising a conically shaped screw head with an external thread could be inserted into the through hole. In the latter case the central bone screw would be inserted into the through holeat a fixed angle (e.g., with the screw axis and the longitudinal axisof the through holecoinciding).

7 8 FIGS.and 2 11 6 9 2 6 As shown in, the peripheral holesare configured so that each of the hole axesis angled at approximately 20° relative to the longitudinal axisof the through hole. In another embodiment of the present invention, the peripheral holesmay be angled at any other angle relative to the longitudinal axisand may optionally also each extend along different angles, as those skilled in the art will understand.

7 FIG. 2 8 1 20 23 21 2 21 22 20 2 23 11 2 As illustrated ineach of the peripheral holestapers radially inward towards the distal surfaceof the bone plate. A peripheral bone screwwith a screw axisand a screw headis inserted into each of the peripheral holes. The screw headis conically shaped and comprises an external threadso each peripheral bone screwcan be inserted into one of the peripheral holesat a fixed angle with the screw axisand the hole axisof the peripheral holecoinciding.

20 21 22 2 23 11 2 Instead of peripheral bone screwscomprising conically shaped screw headswith an external thread, peripheral bone screws comprising spherically shaped screw heads with an external thread may be inserted into the peripheral holes. In the latter case the peripheral bone screws may be inserted at a user selected variable angle between the screw axisand the hole axisof the peripheral hole.

9 11 FIGS.to 1 8 FIGS.to 1 8 FIGS.to 9 2 10 9 15 6 15 6 9 15 15 30 9 6 Inanother embodiment is illustrated which differs from the embodiment ofonly in that the generally polygonal through holecomprises rounded corners instead of the N=3 peripheral holesarranged in the corners. Similarly to the embodiment of, the wallof the through holecomprises n=3 convex sectionswhich in a cross-section orthogonal to the longitudinal axisare centrally located on the sides of an equilateral triangle. Each of the convex sectionsis convexly curved in a cross-section orthogonal to the longitudinal axisof the through holewith the apex of each convex sectionlocated on a middle line orthogonal to one side of the equilateral triangle. Due to the convex sections, a bone screwmay be inserted into the through holeunder a surgeon selected angle relative to the axis.

9 15 10 9 15 5 9 5 The through holeincludes three radially symmetrically arranged convex sectionscentrally located on the sides of an equilateral triangle and three concavely rounded sections in the corners of the equilateral triangle. The wallof the through holetherefore comprises n=3 wall portions whereof each wall portion extends along one side of an equilateral triangle and is limited by a transition to a first concavely rounded section at one of its ends and by a transition to a second concavely rounded section at its other end. In the present embodiment each convex sectionextends over the whole length of the wall portion limited by the transitions. The threador thread-like structure extends over the whole periphery of the through hole. The depth of thread of the threador thread-like structure can decrease in the concavely rounded sections.

10 FIG. 9 8 1 30 33 31 9 31 32 30 33 6 9 As illustrated inthe through holetapers towards the distal surfaceof the bone plate. A central bone screwwith a screw axisand a screw headis inserted in the through hole. The screw headis spherically shaped and comprises an external threadso that the central bone screwcan be inserted into the through hole at a user-selected variable angle α between the screw axisand the longitudinal axisof the through hole.

12 14 FIGS.to 9 11 FIGS.to 9 11 FIGS.to 9 11 FIGS.to 1 9 9 6 14 6 15 14 10 9 15 9 9 5 9 5 15 15 Inanother embodiment of the bone plateis illustrated which comprises two through holes. Similarly to the embodiment of, the through holehas cross-sectional area orthogonal to the longitudinal axiswith a centerlocated on the longitudinal axiswith each of the n=3 convex sectionsbeing limited by two radii intersecting each other in the centerand enclosing an angle Ω which is smaller than 120°. The wallof each of the two through holescomprises n=3 wall portions with each wall portion extending along one side of an equilateral triangle and limited by a transition to a first concavely rounded section at one of its ends and by a transition to a second concavely rounded section at its other end. Similarly to the embodiment of, each convex sectionextends over the whole length of the wall portion limited by the transitions. The through holesdiffer from the through holeof the embodiment ofonly in that the threador thread-like structure does not extend over the whole periphery of the through hole. The depth of thread of the threador thread-like structure decreases on each end of the convex sectionat the transition between the convex sectionand the concavely rounded section in such a way that a portion of the concavely rounded sections is unthreaded.

13 FIG. 9 11 FIGS.to 9 8 1 30 33 31 9 30 31 32 30 9 33 6 9 As illustrated inthe through holetapers radially inward toward the distal surfaceof the bone plate. Similarly to the embodiment of, a central bone screwwith a screw axisand a screw headcan be inserted in the through hole. By using a central bone screwthe screw headof which is spherically shaped with an external thread, the central bone screwmay be inserted into the through holeat a user-selected, variable angle α of the screw axisto the longitudinal axisof the through hole.

15 FIG. 12 14 FIGS.to 9 11 FIGS.to 9 15 15 14 10 9 15 5 9 5 15 15 illustrates a further embodiment of the through holewhich differs from the embodiment ofonly in that it comprises n=4 convex sections. Each of the n=4 convex sectionsis limited by two radii intersecting each other in the centerand enclosing an angle Ω which smaller than 90°. The wallof each of the two through holescomprises n=4 wall portions with each wall portion extending along one side of a square and limited by a transition to a first concavely rounded section at one of its ends and by a transition to a second concavely rounded section at its other end. Similarly to the embodiment of, each convex sectionextends over the whole length of the wall portion limited by the transitions. The threador thread-like structure does not extend over the whole periphery of the through hole. The depth of thread of the threador thread-like structure decreases on each end of the convex sectionat the transition between the convex sectionand the concavely rounded section in such a way that a portion of the concavely rounded sections is unthreaded.

16 FIG. 15 FIG. 9 10 9 15 5 15 illustrates again a further embodiment of the through holewhich differs from the embodiment ofonly in that the wallof the through holecomprises n=4 straight sectionsand that the depth of thread of the threador thread-like structure decreases from a middle line orthogonal to one side of the square towards the transition between the straight sectionand each of the concavely rounded sections in such a way that the concavely rounded sections are unthreaded.

17 18 FIGS.and 14 FIG. 14 FIG. 9 2 2 25 1 7 26 25 8 1 25 2 11 2 15 10 9 illustrate again a further embodiment of the through holewhich differs from the embodiment ofonly in that the N=3 peripheral holesare configured to receive conventional cortex screws. Each peripheral holecomprises a spherical recesspenetrating partially into the bone platefrom the proximal surfaceand axially adjacent to a conically enlarging lower sectionextending between the spherical recessand the distal surfaceof the bone plate. Due to the spherical recess, a conventional cortex screw with a spherical head may be inserted into each of the peripheral holesat a user-selected angle with respect to the axisof the peripheral hole. The n=3 straight or convex sectionsof the wallof the through holeare configured similarly to the embodiment of.

Although the invention and its advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, composition of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention.

It will be appreciated by those skilled in the art that various modifications and alterations of the invention can be made without departing from the broad scope of the appended claims. Some of these have been discussed above and others will be apparent to those skilled in the art.