Patent ID: 12213709

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present disclosure can be understood more readily by reference to the following detailed description taken in connection with the accompanying figures and examples, which form a part of this disclosure. It is to be understood that this disclosure is not limited to the specific devices, methods, applications, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the scope of the present disclosure. Also, as used in the specification including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise.

The term “plurality”, as used herein, means more than one. When a range of values is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. All ranges are inclusive and combinable.

The terms “approximately” and “substantially”, as used herein with respect to dimensions, angles, and other geometries, takes into account manufacturing tolerances. Further, the terms “approximately” and “substantially” can include 10% greater than or less than the stated dimension or angle. Further, the terms “approximately” and “substantially” can equally apply to the specific value stated.

Variable angle (VA) locking screws have a tendency to cause, as well as exhibit, cross-threading within a locking hole in which they are inserted, particularly when the VA locking screw is inserted in the locking hole at an angulated trajectory. Cross-threading of the plate threads can be caused by the external threads on the screw head not fitting within (i.e., interfering with) and thus cross-threading the internal threads of the locking hole. Such thread interference can also cause cross-threading of the external threads of the screw head. Regions of contact between the crests of the screw head threads and portions of the internal threads, particularly at or near the crests of the internal threads at angulation, can be particularly susceptible to cross-threading. Cross-threading is problematic because it reduces the intended interference fit (also referred to as the “form-fit”) between the screw head threads and the internal threads of the locking hole, which can reduce stability and mechanical strength at the locked interface between the screw head and the locking hole.

The embodiments disclosed herein pertain to locking structures employed within a locking hole and complimentary locking structures on the head of a locking screw. These complimentary locking structures define mating threads having complimentary geometries that provide enhanced control over the deformation of the mating threads, particularly over the deformation of the internal threads of the locking hole, which will effectively become re-aligned to the screw axis at angulated insertions. Such favorable geometries include the respective cross-sectional profiles (referred to in the art as “thread-forms”) of the screw head threads and the plate hole threads. These complimentary geometries and profiles can be collectively characterized as “thread proportions” of the plate and screw threads. One way in which the thread profiles disclosed herein control the thread deformation is by providing the screw head threads with a stronger (e.g., larger) profile and interfacing it against an intentionally more malleable (e.g., thinner) profile of the plate hole threads. Another way in which thread deformation is controlled is by adjusting the edge geometry of the thread profiles, such as at the thread crests, to reduce undesirable mechanical interference at the thread interface at angulated screw orientations. The thread proportions disclosed herein have been shown to avoid or reduce cross-threading at angulated screw insertions, and also when the screw insertion involves “timing error”, which is an axial mis-alignment of the screw head threads relative to the plate hole threads. Thus, the threaded locking structures described herein can lock with the heads of VA locking screws at angulation, as well as both VA and standard-type locking screws at nominal orientations, in a manner that inhibits (or at least reduces) cross-threading, or at least substantially causes any cross-threading to occur substantially entirely within the plate threads as an act of plastic and clastic thread deformation. The threaded locking structures described herein have also been demonstrated to increase the overall cantilever strength at the locking thread interface.

Referring toFIG.1A, a bone fixation system2includes a bone plate4having a plate body5that defines therein one or more fixation holes, such as variable-angle (VA) locking holes6. The VA locking holes6are configured to receive anchor members, such as locking screws8, for example, that are configured to affix the bone plate4to one or more portions of bone. The plate body5defines internal threads9within the VA locking holes6. Accordingly, the internal threads9can also be referred to as “plate hole threads” or simply “plate threads” or “hole threads.” The plate threads9traverse locking structures, such as columns26, defined within the VA locking holes6. Thus the columns26can be referred to as “threaded columns”. The threaded columns26are configured such that, during insertion of a locking screw8within the VA locking hole6, a screw shaft25of the locking screw8bypasses the columns26, which in turn engage external threads29on the screw head27of the locking screw8in a manner providing enhanced locking engagement between the locking screw8and the bone plate4, as set forth in more detail below.

The bone plate4can be a bridge plate, as shown, although other bone plate types and configurations are within the scope of the present disclosure. The plate body5can define a first end10and a second end12spaced from each other along a longitudinal direction X and a first lateral side14and a second lateral side16spaced from each other along a lateral direction Y that is substantially perpendicular to the longitudinal direction X. The bone plate4can also define an upper plate surface18configured to face away from the bone and an opposed lower plate surface20configured to face the bone. The upper and lower plate surfaces18,20are spaced from each other along a vertical direction Z substantially perpendicular to each of the longitudinal direction X and the lateral direction Y. It is to be appreciated that, as used herein, the terms “longitudinal”, “longitudinally”, and derivatives thereof refer to the longitudinal direction X; the terms “lateral”, “laterally”, and derivatives thereof refer to the lateral direction Y; and the terms “vertical”, “vertically”, and derivatives thereof refer to the vertical direction Z.

The VA locking holes6extend from the upper plate surface18to the lower plate surface20along a central hole axis22. The central hole axis22is oriented along an axial hole direction. As used herein, the term “axial direction” (e.g., “axial hole direction” and “axial screw direction”) is defined as the direction along which the respective axis extends. Furthermore, the directional terms “axial”, “axially”, and derivatives thereof refer to the respective axial direction. Thus, as used herein, the directional term “axially upward” and derivatives thereof refers to the axial hole direction from the lower plate surface20toward the upper plate surface18. Conversely, the term “axially downward” and derivatives thereof refers to the axial hole direction from the upper plate surface18toward the lower plate surface20. Thus, “axially upward” and “axially downward” are each mono-directional components of the “axial direction”, which is bi-directional. In the embodiments depicted in the Figures, the axial hole direction (and thus also the central hole axis22) is oriented along the vertical direction Z. Accordingly, the axial hole direction is also denoted by “Z” throughout this disclosure. It should be appreciated, however, that the scope of the present disclosure covers embodiments in which the axial hole direction (and thus also the central hole axis22) is offset from the vertical direction Z at an oblique angle. It should also be appreciated that when the terms “axially upper”, “axially lower,” and the like are used with reference to the VA locking screw8, such terms refer to a central axis23of the screw8, particularly as it would be oriented within the VA locking hole6.

The plate body5and the locking screws8can each comprise one or more biocompatible materials. By way of non-limiting examples, the plate body5can be formed of a material selected from a group comprising: metal, such as titanium, titanium alloys (e.g., titanium-aluminum-niobium (TAN) alloys, such as Ti-6Al-7Nb, and titanium-aluminum-vanadium (TAV) alloys such as Ti-6Al-4V, titanium molybdenum alloys (Ti—Mo) or any other molybdenum metal alloy, and nickel-titanium alloys, such as nitinol), stainless steel, and cobalt base alloys (e.g., cobalt-chrome alloys); composite materials; polymeric materials; ceramic materials; and/or resorbable materials, including resorbable versions of the foregoing material categories (metals, composites, polymers, ceramics). Also by way of non-limiting examples, the locking screws8can be formed of a material selected from a group comprising: metal, such as titanium, titanium alloys (e.g., TAN alloys, TAV alloys, such as Ti-6Al-4V, titanium molybdenum alloys (Ti—Mo) or any other molybdenum metal alloy, and nickel-titanium alloys, such as nitinol), stainless steel, cobalt base alloys (e.g., cobalt-chrome alloys); composite materials; polymeric materials; ceramic materials; and/or resorbable materials, including resorbable versions of the foregoing material categories (metals, composites, polymers, ceramics). Preferably, the material of the locking screw8has a hardness that is greater than that of the material of the plate body5. This parameter contributes to the locking characteristics described throughout the present disclosure. Preferably, the plate body5primarily or entirely comprises titanium and the locking screws8primarily or entirely comprise TAN. It should be appreciated, however, that other material compositions of the bone plates4and/or the locking screws8are within the scope of the present disclosure.

Moreover, surfaces of the plate body5and/or the locking screws8can optionally be subjected to one or more processes, such as coating, treating, and/or finishing processes, which can be performed to provide such surfaces, or the underlying subject body material, with certain characteristics, such as to adjust hardness, softness, and/or friction parameters of the body material. Non-limiting examples of coatings include DLC, TiN, AlTiN and other coatings that provide, among other things, lubrication, a coefficient of friction different than that of the underlying material, and/or a surface hardness different than that of the underlying material. Non-limiting examples of surface treatments include processes for hardening outer surfaces of the body material, such as hard anodization and diffusion hardening, the latter of which can include diffusing nitrogen, oxygen, carbon, and/or zirconium into the plate body5and/or locking screw8surfaces. Additional or alternative surfaces treatments can include annealing or other processes for softening the body material, particularly the plate body5material, though such softening processes can also be employed on the screw8body material. The foregoing processes can be employed, for example, to provide beneficial thread deformation performance at the thread interface, as described throughout the present disclosure, and/or to allow mating thread surfaces to effectively slide against one another with less friction and thus less unwanted deformation. It should be appreciated that the plate body5and the locking screws8can be subjected to different processes. Moreover, either or each of the plate body5and locking screws8need not be subjected to any of the foregoing processes.

Furthermore, the dimensions set forth throughout this disclosure are made in reference to bone fixation systems2that includes at least one VA locking hole6and at least one VA locking screw8configured for nominal or angulated insertion within the at least one VA locking hole6, in which the screw shaft25of the VA locking screw8defines a major diameter in a range of about 0.5 mm to about 10.0 mm, more particularly in a range of about 1.0 mm to about 7.0 mm, more particularly in a range of about 2.0 mm to about 4.0 mm, and more particularly a major diameter of about 3.5 mm. The foregoing screw shaft25sizes can correspond to the threaded head27defining a major diameter in a range of about 0.7 mm to about 15.0 mm, more particularly in a range of about 1.0 mm to about 12.0 mm, more particularly in a range of about 2.0 mm to about 10.0 mm, and more particularly in a range of about 3.0 mm to about 7.0 mm. It is to be appreciated, however, that any of the embodiments described below can be scaled upward or downward in size as needed for employment within larger or smaller bone fixation systems.

Referring now toFIG.1B, the VA locking holes6can be configured to provide enhanced affixation with multiple types of locking screws8, including VA locking screws8as well as standard-type locking screws, including such screws having various lengths, so as to allow a physician to implant the bone plate4to one or more bones or bone segments as desired. By way of non-limiting example, as shown, the bone plate4can be coupled to a long-bone100via locking screws8in a manner affixing fractured segments101,102of the bone together. The VA locking holes6described herein can lock with VA locking screws8or standard-type locking screws at a nominal orientation whereby a central screw axis23thereof is substantially aligned with the central hole axis22. The VA locking holes6can also lock with VA locking screws8at an angulated orientation whereby the central screw axis23is oriented at an acute angle A1with respect to the respective central hole axis22. Acute angle A1can also be referred to as the “angle of angulation” or simply the “angulation.” VA locking screws8and standard-type locking screws and their locking functionalities are described more fully in U.S. Pat. No. 9,314,284, issued Apr. 19, 2016, in the name of Chan et al. (“the '284 Reference”), and U.S. patent application Ser. No. 15/940,761, filed Mar. 29, 2018, in the name of Bosshard, et al. (“the '761 Reference”), and Ser. No. 15/966,047, filed Apr. 30, 2019, in the name of Bosshard, et al. (“the '047 Reference”) the disclosures of each of which are hereby incorporated by reference as if set forth in their entireties herein.

During a bone plating operation, the screw shaft25of a locking screw8can be inserted through one of the VA locking holes6and driven into the underlying bone100. In particular, rotation of the locking screw8causes its threaded screw head27to threadedly mate with the VA locking hole6. As a result, the screw head27fastens the bone plate4to the underlying bone100substantially without applying a compressive force onto the bone plate4against the underlying bone100. The bone plate4can be spaced from the underlying bone100when locked to the threaded screw head27. Alternatively, the bone plate4can abut the underlying bone100when locked to the threaded screw head27.

It is to be appreciated that, during a plating operation, the first locking screw8inserted through one of the VA locking holes6and into underlying bone100has the benefit of being able to generally mate with the plate threads9so that crests of the screw head thread29advance helically substantially along the roots of the plate threads9. However, once the first locking screw8is locked to the bone plate4thereby fastening the plate4to the underlying bone100, the subsequent locking screws8often lack the ability to have their external thread crests advance helically along the plate thread9roots. This results because, once the screw shafts25of these subsequent locking screws8advance through the VA locking holes6and threadedly purchase into the underlying bone100, the relative axial positions of the screw head threads29and the plate threads9are substantially a function of the screw's threaded purchase with the underlying bone100. This axial misalignment of the screw head threads29relative to the plate threads9is referred to herein as “timing error.”

Referring now toFIGS.2A through2C and2E, each of the VA locking holes6can be defined by an interior surface24of the plate body5. Alternatively, the interior surface24can be defined by an insert plate body5a, which can also be referred to an “insert” or “inlay”, that is fitted within an axial aperture or receptacle95of the plate body5, as indicated in dashed lines inFIG.2E. It should be appreciated that the bone fixation system2can include a plurality of interchangeable inserts5ahaving different hole6shapes and geometries and/or different thread parameters, each being insertable within the receptacle95, such that the physician can select the particular insert5ahaving the desired VA locking hole6geometry, as needed. Typically, at least a portion of the interior surface24is tapered as it extends axially downward. Thus, the interior surface24is configured to prevent the screw head27from passing completely through the VA locking hole6.

The interior surface24can define the threaded columns26. The columns26extend axially between the upper and lower plate surfaces18,20. Within each (or at least some of) the VA locking holes6, the columns26are sequentially located about a circumference of the interior surface24. The interior surface24also defines a plurality of recesses28sequentially located circumferentially between the columns26. The recesses28extend axially between the upper and lower plate surfaces18,20. The columns26and recesses28can be evenly spaced about the circumference of the interior surface24within the VA locking hole6. However, in other embodiments, the columns26and/or recesses28can be un-evenly spaced about the circumference of the VA locking hole6.

The plate threads9extend through the columns26and at least portions of the recesses28along one or more thread paths between the upper and lower plate surfaces18,20. As shown, the one or more thread paths can include a pair of non-intersecting thread paths (i.e., double-lead); however in other embodiments the one or more thread paths can include a single thread path (i.e., single-lead), or three or more thread paths (e.g., triple-lead, etc.). The thread paths are preferably helical, although other thread path types are within the scope of the present disclosure. As shown, portions of the recesses28can circumferentially interrupt the plate threads9. Stated differently, the plate threads9can “bottom-out” along one or more and up all of the recesses28. In other embodiments, however, the plate threads9can circumferentially traverse one or more and up to each of the recesses28in an uninterrupted fashion (i.e., the plate threads9need not bottom-out in the recesses28).

The plate threads9have a cross-sectional profile in a reference plane that extends along the central hole axis22. Such as cross-sectional profile is also referred to as a “thread-form,” and includes crests56, roots58, and upper and lower flanks55,57that extend between the crests56and roots58, as shown inFIG.2B. As used herein with reference to the plate threads9, the term “crest” refers to the apex of a fully-developed thread-form. Each threaded column26defines one or more thread segments52extending along the thread path(s). As used herein, the term “thread segment” refers to any portion of a thread, such as the plate threads9and the screw head threads29, that has a thread-form and a length along its thread path. The thread segments52of the plate threads9can also be referred to herein as “plate thread segments”52. Plate thread segments52that traverse a column26can be referred to herein as “column threads”54.

The interior surface24can define an upper perimeter30of the VA locking hole6at an interface with the upper plate surface18and a lower perimeter32of the VA locking hole6at an interface with the lower plate surface20. The upper and lower perimeters30,32can each be circular in shape, although other shapes are within the scope of the present disclosure, as discussed in more detail below. The interior surface24can also define one or more lead-in surfaces34that taper axially downward from the upper perimeter30to one or more of the columns26. As shown, the one or more lead-in surfaces34can include a single lead-in surface34can be circumferentially interrupted by one or more of the recesses28. Alternatively, the lead-in surface34can extend circumferentially continuously and uninterrupted along a full revolution about the central hole axis22. The interior surface24can also define an undercut surface36that tapers axially upward from the lower perimeter32. The undercut surface36can extend circumferentially continuously and uninterrupted along a full revolution about the central hole axis22. Alternatively, the undercut surface36can be circumferentially interrupted by one or more of the recesses28.

Referring now toFIG.2D, in an example embodiment, the VA locking hole6can include four (4) columns26and four (4) recesses28evenly spaced about the central hole axis22. The columns26can include a first column26a, a second column26b, a third column26c, and a fourth column26devenly spaced about the central hole axis22. The recesses28can include: a first recess28alocated circumferentially between the first and second columns26a,26b; a second recess28blocated circumferentially between the second and third columns26b,26c; a third recess28clocated circumferentially between the third and fourth columns26c,26d, and a fourth recess28dlocated circumferentially between the fourth and first columns26d,26a. It should be appreciated that the design of the VA locking hole6is not limited by the number of columns26and recesses28, as described in more detail below.

Each of the recesses28a-dcan define a central recess axis37, each of which can be parallel with the central hole axis22, although other central recess axis37orientations are possible. Each central recess axis37can also be radially spaced from the central hole axis22by radial distance R1. Each recess defines a recess radius R10. As shown, each of the recesses28a-dhas a horizontal profile (i.e., a profile in a reference plane orthogonal to the central hole axis22) that subsumes about half of a circle. In the illustrated embodiment, each of the recesses28a-28dis generally shaped as a section of a cylinder. In other embodiments, one or more an up to all of the recesses can have a downward-tapering frusto-conical shape. Other recess shapes are also within the scope of the present disclosure. Each recess28defines a radially-outermost region or apex39, as measured from the central hole axis22. Each recess apex39can extend along a plane, along which the central hole axis22also extends. In the depicted embodiments, the recess apices39are parallel with the central hole axis22. In other embodiments, the recess apices39can be oriented at an acute angle relative to the central hole axis22.

Each column26can define a first surface42substantially facing the central hole axis22. The first surface42can also be referred to as an “innermost surface” of the column26. Thus, the first surface42defines the crests56of the column threads54. In a horizontal reference plane (such as reference plane M shown inFIG.2E), the first surface42of each column26preferably extends arcuately about the central hole axis22and defines a shared or common radius R8. The first surface42of each column26can also extend between a first side44and a circumferentially opposed second side45of the column26. The first and second sides44,45of each column26can define interfaces between the column26and the circumferentially adjacent recesses28. For example, the first side44of the first column26acan define an interface between the first column26aand the fourth recess28d; the second side45of the first column26acan define an interface between the first column26aand the first recess28a; the first side44of the second column26bcan define an interface between the second column26band the first recess28a; the second side45of the second column26bcan define an interface between the second column26band the second recess28b; and so forth along the circumference of the interior surface24. The first surfaces42of the columns26can collectively define circumferential segments of a downward-tapering frusto-conical shape, particularly one that defines a central cone axis coincident with the central hole axis22.

With reference toFIG.2E, each column26can define a crest centerline46that is disposed circumferentially equidistantly between the first and second sides44,45of the column26. In each column26, the crest centerline46extends along the first surfaces42and thus intersects the crests56of the column threads54. The crest centerline46of each column26is coplanar with the central hole axis22in a respective axial reference plane. In this manner, each crest centerline46also defines a crest trajectory of the column threads54in the axial reference plane. Accordingly, the crest centerline46can also be referred to as a “crest trajectory axis”46. Each column26can also define a root centerline48that is disposed circumferentially equidistantly between the first and second sides44,45of the column26. In each column26, the root centerline48intersects the roots58of the column threads54. The root centerline48of each column26is coplanar with the crest centerline46and the central hole axis22in the respective axial reference plane. In this manner, each root centerline48also defines a root trajectory of the column threads54in the axial reference plane. Accordingly, the root centerline48can also be referred to as a “root trajectory axis”48. The crest trajectory axis46can be oriented at an acute angle A2relative to the central hole axis22. The root trajectory axis48can also be oriented at an acute angle A3relative to the central hole axis22. Acute angles A2and A3can be in a range of about 5 degrees to about 30 degrees. In additional embodiments, the angles A2, A3can be in a range of about 10 degrees to about 20 degrees, and can further be in a range of about 13 degrees to about 17 degrees. The crest and root trajectory axes46,48are preferably parallel, as shown. In other embodiments, however, the crest and root trajectory axes46,48of one or more and up to all of the columns26can be oriented at an acute angle relative to one another, as described in the '761 Reference. The column threads54can also define a thread midline60, which can lie in the common plane with the crest and root trajectory axes46,48and the central hole axis22, as also shown inFIG.2F. The thread midline60is equidistantly spaced between the crest and root trajectory axes46,48.

The crest trajectory axis46can be radially spaced from the central hole axis22by a distance R2measured along a reference plane M that is orthogonal to the central hole axis22and located at the vertical center of the VA locking hole6. Thus, the reference plane M can be characterized as the axial “mid-plane” of the VA locking hole6. The thread midline60can be radially spaced from the central hole axis22by a distance R3measured along the hole mid-plane M. The root trajectory axis48can be radially spaced from the central hole axis22by a distance R4measured along the hole mid-plane M. Distance R2can be characterized as the mean crest radius of the column threads54. Distance R3can be characterized as the mean radius of the column threads54. Distance R4can be characterized as the mean root radius of the column threads54. It should be appreciated that any of the mean crest radius R2, the mean radius R3, and the mean root radius R4can optionally be used as a metric for categorizing the size of the hole6.

Referring now toFIG.2F, each plate thread segment52, as an internal thread, can be axially centered at the root58, and includes the upper flank55extending from the root58to the axially upward crest56, and also includes the lower flank57extending from the root58to the axially lower crest56. Each plate thread segment52is configured to intermesh with (i.e., at least partially house) at least one associated thread segment of the screw head threads29, as described in more detail below. The plate threads9define a thread pitch P1that extends between axially adjacent crests56along the axial direction. The plate threads9also define a thread lead L1, which can also be defined at the crests56. The thread pitch P1of the column threads54can be in a range of about 0.05 mm to about 5.0 mm, more particularly in a range of about 0.05 mm to about 2.0 mm, more particularly in a range of about 0.1 mm to about 1.5 mm, more particularly in ranges of about 0.2 mm to about 1.0 mm, about 0.3 mm to about 0.8 mm, about 0.4 mm to about 0.6 mm, about 0.15 mm to about 0.6 mm, and preferably about 0.4 mm. The thread lead L1can be in a range of 0.05 mm to about 5.00 mm, about 0.05 mm to about 2.0 mm, about 0.1 mm to about 1.5 mm, about 0.2 mm to about 1.0 mm, about 0.3 mm to about 0.8 mm, about 0.4 mm to about 0.6 mm, about 0.3 mm to about 1.2 mm, about 0.15 mm to about 0.6 mm, about 0.4 mm, and preferably about 0.8 mm. It should be appreciated that in embodiments where the plate threads9are double-lead threads, such as those depicted, the thread lead L1is twice the distance of the thread pitch P1(i.e., L1=2×P1). In embodiments where the plate threads9are single-lead threads, the thread lead L1and thread pitch P1are equivalent to each other. In embodiments where the plate threads9are triple-lead threads, the thread lead L1is three-times the distance of the thread pitch P1(i.e., L1=3×P1). Thus, the thread “lead” factor is a multiple by which the thread lead L1is measured relative to the thread pitch P1.

Referring now toFIG.2G, the cross-sectional profiles (i.e., thread-forms) of the plate threads9in the axial reference plane will now be described. These cross-sectional profiles can also be referred to herein simply as “thread profiles”. In the illustrated embodiment, this reference plane also contains the root trajectory axis48. The thread profiles of the plate threads9are substantially similar in each of the respective axial reference planes of the various thread columns26. As described above, these thread profiles, and the edge geometries thereof, are configured to be complimentary with those of the screw head threads29to provide favorable mating engagement therebetween, such as for controlling thread deformation of, and/or reducing undesirable mechanical interference between, the plate threads9and the screw head threads29.

The first and second flanks55,57are offset from one another at an angle A4, which defines the thread angle of the plate threads9. Accordingly, angle A4can also be referred to as “thread angle” A4of the plate threads9or the “plate thread angle” A4. In the illustrated embodiment, the crests56of the plate thread segments52are truncated for reducing undesirable mechanical interference with the screw head threads29. Additionally, the first and second flanks55,57can be offset from one another at a plurality of angles. For example, in the illustrated embodiment, upper and lower flanks55,57of the plate thread segments52are also truncated adjacent the crests56in a manner providing the plate thread segments52with a second thread angle A5adjacent the crests56. The plate threads9of such an embodiment can be referred to as “dual-angle” threads. It should be appreciated that the flanks55,57of the plate thread segments52can define yet additional thread angles, such as a third thread angle, a fourth thread angle, etc. In such multi-angle embodiments, including dual-angle embodiments, thread angle A4can be referred to as a “first thread angle” A4. In yet further embodiments, the flanks55,57(or at least portions thereof) can have arcuate profiles, which can theoretically define an infinite number of thread angles. The particular edge geometries of the thread profiles defined by the truncated crests and truncated flanks55,57are described in more detail below.

In each plate thread segment52, the root58defines a root profile, the crests56define crest profiles, and the upper and lower flanks55,57define respective upper and lower flank profiles. In the illustrated embodiment, and with reference to a radially inward direction, the profile of the upper flank55includes:a) a first upper flank portion55athat extends from a first upper flank reference point55-1to a second upper flank reference point55-2;b) a second or “primary” upper flank portion55bthat extends along a consistent geometry from the second upper flank reference point55-2to a third upper flank reference point55-3; andc) a third upper flank portion55cthat extends from the third upper flank reference point55-3to a lower crest reference point56-1.
Similarly, in the illustrated embodiment, and with reference to the radially inward direction, the profile of the lower flank57includes:a) a first lower flank portion57athat extends from a first lower flank reference point57-1to a second lower flank reference point57-2;b) a second or primary lower flank portion57bthat extends along a consistent geometry from the second lower flank reference point57-2to a third lower flank reference point57-3; andc) a third lower flank portion57cthat extends from the third lower flank reference point57-3to an upper crest reference point56-2.
The first upper and lower flank portions55a,57aare coincident with each other and with a root reference point58-1, which is located at the root58(i.e., the location of the thread segment52spaced furthest from the crest trajectory axis46). Additionally, the first upper and lower flank portions55a,55bcan each define a relief surface extending from the root58. As shown, the first upper and lower flank portion55a,57acan each be arcuate and can define a shared or common relief radius R5, which is configured to reduce stress concentrations at the root58. Thus, the first upper and lower flank portion55a,57acan be referred to as respective “root relief” portions55a,57aof the upper and lower flanks55,57. Because the root relief portions55a,57aof the illustrated embodiment have a common boundary at the first root reference point58-1, the root58profile of each thread segment52substantially consists of a single point in the axial reference plane. In other embodiments, however, the root58can define an elongated root profile, which can extend linearly between the first upper and lower flank reference points55-1,57-1along the root trajectory axis48(as described in more detail below with reference to the embodiment shown inFIGS.5B and5C).

The primary upper and lower flank portions55b,57beach extend along a consistent geometry in the axial reference plane. As used herein, the term “consistent geometry” means a line, a regular curve, or a portion of a non-regular curve which portion does not include an inflection and does not backtrack on itself. Non-limiting examples of such curves having a consistent geometry include an involute curve, as more fully described in the '047 Reference, and a curve having a constant, relatively large radius. In the illustrated embodiment, the primary flank portions55b,57bextend linearly and define the first thread angle A4. Additionally, the third upper and lower flank portions55c,57cof the illustrated embodiment define the second thread angle A5therebetween and are offset from the respective primary flank portions55b,57b. The first thread angle A4of the plate can be in a range of about 28 degrees to about 32 degrees, and can also be in a range of about 20 degrees to about 40 degrees, and can further be in a range of about 15 degrees to about 50 degrees. The second thread angle A5of the plate can be in a range of about 53 degrees to about 57 degrees, and can also be in a range of about 45 degrees to about 65 degrees, and can further be in a range of about 40 degrees to about 75 degrees. In other embodiments, the primary flank portions55b,57band the respective third upper and lower flank portions55c,57cof any and up to each of the flank profiles need not have a common boundary at the third lower flank reference point57-3. For example, such flank profiles can include a transition portion, which can be arcuate, extending between the primary flank portions55b,57band the respective third upper and lower flank portions55c,57c. In such embodiments, it should be appreciated that the third upper and lower flank reference points55-3,57-3continue to define radially inward ends of the primary flank portions55b,57b.

Furthermore, the thread profiles of the column threads54include crest profiles56athat are truncated. In the illustrated embodiment, the crest profile56aextends linearly from the lower crest reference point56-1to the upper crest reference point56-2along the crest trajectory axis46, which is also linear. This linear crest profile56ais configured to further reduce stress concentrations at the crest56. Additionally, each crest profile56acan define a crest width W1, as measured between the upper and lower crest reference points56-1,56-2along the axial plate direction. Additionally, it should be appreciated that the third upper and lower flank portions55c,57c, which can be characterized as chamfers or bevels, can effectively define relief surfaces for the crest56, which relief surfaces are configured to further reduce stress concentrations at the crest56. Thus, the third upper and lower flank portion55c,57ccan be referred to as respective “crest relief” portions of the flank55,57profiles.

It should be appreciated that the foregoing geometries of the plate thread profiles are provided as examples, and that other profile geometries are within the scope of the present disclosure. For example, the crest profile56aof one or more and up to all of the thread segments52in the column26can optionally be rounded, radiused, chamfered, and/or beveled, with the crest56itself located at the apex of the crest profile56a. Moreover, the root relief portions55a,57aof the flanks55,57can be linear and can extend to the root58.

The column threads54define a thread height H1measured from the crests56to the roots58along a direction DP1that is perpendicular to the crest trajectory axis46. In particular, the thread height H1of any of the plate thread segments52can be measured from the crest trajectory axis46to the root58of the respective thread segment52along direction DP1. Alternatively or additionally, the thread height H1of any of the plate thread segments52can be measured from the crest56to the root trajectory axis48along direction DP1. The thread height H1of the plate column threads54can be in a range of about 0.05 mm to about 2.0 mm, more particularly in a range of about 0.1 mm to about 1.5 mm, more particularly in a range of about 0.2 mm to about 1.0 mm, and more particularly in ranges of about 0.3 mm to about 0.55 mm, about 0.35 mm to about 0.48 mm, and about 0.40 mm to about 0.44 mm, and can also be in a range of about 0.32 mm to about 0.48 mm, and can further be in a range of about 0.20 mm to about 0.55 mm. It is to be appreciated that the thread height H1of the plate thread segments52can be constant along the crests56of the column26.

With continued reference toFIG.2G, it should be appreciated that the thread profiles of the column threads54described above deviate from a reference cross-sectional thread profile (i.e., thread-form) that is V-shaped in the axial reference plane, such as the standardized reference thread-forms of the Unified Thread Standard (UTS) and the International Organization for Standardization (ISO). The reference cross-sectional thread profile is also referred to herein as the “reference profile” of the column threads54. The deviation of the thread profiles from the reference profiles of the column threads54cause the actual thread height H1to be less than a theoretical maximum thread height H2defined by the reference profiles. This theoretical maximum thread height H2can also be referred to herein as the “reference height” H2of the column threads54. The crests56being truncated and/or relieved and the roots58being relieved collectively (and each individually) provides such deviations from the reference profile. Additionally, multi-angle flanks55,57and/or or arcuate flank portions also provide deviations from the reference cross-sectional thread profile. The reference height H2of the column threads54is measured, in the axial reference plane, along direction DP1from a root reference axis48ato a crest reference axis46a. The crest reference axis46aintersects crest reference points56-3defined at the apices of the reference profile on a first side thereof. Similarly, the root reference axis48aintersects root reference points58-2defined at apices of the reference profile on a second side thereof opposite the first side.

The reference profile is defined by the actual thread profile of the column threads54. For example, the reference profile has a thread pitch and thread lead equivalent to those of the column threads54. Additionally, the reference profile is coincident with the thread profile at least at one recurring location of each thread segment52in the axial reference plane. For example, as shown inFIG.2G, the reference profile can be coincident with each of the upper and lower flanks55,57at least at the second reference points55-2,57-2thereof, and also at each location along the linear primary flank portions55b,57b, including at the third reference points55-3,57-3thereof. Thus, for primary flank portions55b,57bthat are linear, as in the embodiment illustrated inFIG.2G, each crest reference point56-3can also be defined as the intersection of: (1) a projection55dof the respective primary upper flank portion55b, which projection55dextends from the third upper flank reference point55-3and along the consistent linear geometry of the primary upper flank portion55btoward the central hole axis22, and (2) a projection57dof the respective primary lower flank portion57bthe adjacent, axially upward thread segment52, which projection57dextends from the third lower flank reference point57-3and along the consistent linear geometry of the primary lower flank portion57btoward the central hole axis22. In such embodiments, the crest reference points56-3of the column threads54represent the theoretical crest locations at which these linear primary upper and lower flank portions55b,57bwould converge if they extended uninterrupted (i.e., in an un-truncated fashion) toward the central hole axis22.

Similarly, in embodiments where the primary flank portions55b,57bare linear, each root reference point58-2can also be defined as the intersection of: (1) a projection55eof the respective primary upper flank portion55b, which projection55eextends from the second upper flank reference point55-2and along the consistent linear geometry of the primary upper flank portion55baway from the central hole axis22, and (2) a projection57eof the respective primary lower flank portion57bthe adjacent, axially downward thread segment52, which projection57eextends from the second lower flank reference point57-2and along the consistent linear geometry of the primary lower flank portion57baway from the central hole axis22. In such embodiments, the root reference points58-2of the column threads54represent the theoretical root locations at which these linear primary upper and lower flank portions55b,57bwould converge if they extended uninterrupted (i.e., in an un-relieved fashion) away from the central hole axis22. Additionally, in view of the foregoing, it is to be appreciated that the reference height H2represents the theoretical maximum thread height if the primary upper and lower flank portions55b,57bof the column threads54extended linearly from un-truncated or un-relieved crests (i.e., at the crest reference points56-3) to un-relieved, intersecting roots (i.e., at the root reference points58-2).

Referring now toFIG.2H, an example embodiment of the column threads54is shown, in which the column threads54have arcuate flank profiles that deviate from the reference profile to cause the thread height H1to be less than the reference height H2. In this example embodiment, the consistent geometry of the primary portions55b,57bof the upper and lower flanks55,57is an involute curve, which extends radially inward from the respective second flank reference point55-2,57-2. In this particular example, the primary portions55b,57bextend all the way to the crest reference point56-1located at the crest56. It should be appreciated that the crest56can optionally be further relieved and/or truncated, such as by being chamfered, beveled, and/or rounded, by way of non-limiting examples. The reference profile can be coincident with each of the upper and lower flanks55,57at least at the second flank reference points55-2,57-2thereof, that is at the location at which the primary flank portions55b,57bintersect the root relief portions55a,57a. It should be appreciated that, when the root relief portions55a,57aare arcuate (including along an involute curve, as shown), the lines of the V-shaped reference profile can be defined as extending tangentially from the root relief portions55a,57aat the second reference points55-2,57-2. As described above, the lines of the reference profile extend from crest reference points56-3to root reference points58-2.

Referring now toFIG.2I, the curved profile of the flanks55,57defines a varying thread angle A10. At any radial location RD of the column threads54, the varying thread angle A10can be defined as the angle between a pair of tangent lines T1, T2intersecting the primary flank portions55b,57bat respective locations L10, L20along a reference line L30parallel with the thread midline60and coincident with the radial location RD. In such embodiments, the varying thread angle A10can vary within any of the ranged described above with reference to angle A4.

Referring now toFIG.3A, the head27of the VA locking screw8defines a proximal end70and a distal end72spaced from the proximal end70along an axial screw direction Z2oriented along the central screw axis23. The head27also defines an outer surface74that extends from the proximal end70to the distal end72and defines the external screw head threads29. In the illustrated embodiment, the external screw head threads29extend substantially from the proximal end70to substantially the distal end72of the head27along one or more thread paths, which can be helical. The external screw head threads29define crests76spaced radially outwardly from roots78with respect to the central screw axis23. The screw head threads29also define upper flanks75and lower flanks77that extend from the crests76to respective axially upper and lower roots78.

The screw head threads29can define a thread pitch P2and a thread lead L2, which can be measured with respect to the roots78. As shown, the one or more thread paths can include a pair of non-intersecting thread paths, such as double-lead threads, in which the threads29define a thread lead L2that is equivalent to twice the thread pitch P2. However, in other embodiments, the one or more thread paths of the screw head threads29can include a single thread path (i.e., single-lead) or three or more thread paths (e.g., triple-lead, etc.). The one or more thread paths of the plate head threads29are configured to be complimentary with the one or more thread paths of the plate threads9. It should be appreciated, however, that the screw head threads29and the plate threads9need not have the same number of thread paths. By way of a non-limiting example, one of the plate threads9and the screw head threads29can be double-lead threads defining a thread pitch, while the other of the plate threads9and screw head threads29can be single-lead threads having a thread lead that is substantially equivalent to the foregoing thread pitch. Other variations in the thread paths of the plate threads9and the screw threads29are also within the scope of the present disclosure.

Referring now toFIG.3B, in an axial reference plane that extends along the central screw axis23, the external screw head threads29define a crest trajectory axis86that intersects the crests76and a root trajectory axis88that intersects the roots78. As shown, the crest trajectory axis86and the root trajectory axis88can define arcuate, convex shapes, which is advantageous for angulated locking with the plate threads9. In additional embodiments, the crest and root trajectory axes86,88can be generally spherical. As used herein, the term “spherical” its derivatives means at least a portion of a sphere or at least a portion of a spheroid, including such portions of a prolate spheroid and/or an oblate spheroid, by way of non-limiting examples, and also encompasses substantial approximations of such portions of a sphere and/or spheroid. It should be appreciated, however, that other crest and root trajectory axis86,88geometries are within the scope of the present disclosure, including those described more fully in the '284 Reference.

The external screw head threads29can be characterized as defining a sequence of helically-adjacent screw head thread segments73, which can extend continuously or discontinuously along the one or more thread paths. As depicted, the screw head threads29can define thread segments73that are axially adjacent. Because the screw head threads29are external threads, each thread segment73thereof can be axially centered at the crest76, and includes the upper flank75ascending from the crest76to the axially upward root78, and also includes the lower flank77descending from the crest76to the axially lower root78. Accordingly, each thread segment73of the screw head threads29is configured to intermesh with (i.e., at least partially reside within) at least one associated thread segment52of the plate threads9. The upper and lower flanks75,77of axially adjacent thread segments73are offset from one another at an angle A6, which defines the thread angle of the screw head threads29. Thus, angle A6can also be referred to the “head thread angle” A6.

Referring now toFIG.3C, the thread profiles (i.e., thread-forms) of the screw head threads29will now be described, as defined within the axial reference plane that contains (and is thus oriented along) the central screw axis23.

As above, the crests76define crest profiles; the roots78define root profiles; and the upper and lower flanks75,77define respective upper and lower flank profiles. In the illustrated embodiment, and with reference to a radially outward direction away from the central screw axis23, the profile of the upper flank75includes:a) a first upper flank portion75a(also referred to as a “root relief portion”) that extends from a first upper flank reference point75-1to a second upper flank reference point75-2; andb) a second or “primary” upper flank portion75bthat extends along a consistent geometry from the second upper flank reference point75-2to an upper crest reference point76-1.
Similarly, in the illustrated embodiment, and with reference to the radially inward direction, the profile of the lower flank77includes:a) a first lower flank portion77a(also referred to as a “root relief portion”) that extends from a first lower flank reference point77-1to a second lower flank reference point77-2; andb) a second or primary lower flank portion77bthat extends along a consistent geometry from the second lower flank reference point77-2to a lower crest reference point76-2.
As above, the root relief portions75a,77aare configured for reducing stress concentrations at the roots78of the screw head threads29. In the illustrated embodiment, the lower root relief portion77aof a thread segment73is coincident with the upper root relief portion75aof the axially lower head thread segment73. In particular, reference points77-1and75-1are coincident with each other and with a root reference point78-1, which is coincident with the root78(i.e., the nadir of the thread segment73). As shown, these contiguous root relief portions77a,75acan each be arcuate and can define a common relief radius R6, which can be in a range of about 0.005 mm to about 0.10 mmm, more particularly in a range of about 0.02 mm to about 0.08 mm, more particularly in a range of about 0.03 mm to about 0.05 mm, and can also be greater than 0.10 mm (i.e., not less than 0.10 mm), including a relief radius large enough to approximate a linear root profile in the axial reference plane. Accordingly, the first lower and upper flank portions77a,77acan be referred to as respective “root relief” portions of the flanks77,75. As depicted, the root78profile of each head thread segment73can consist of a single point78-1, although in other embodiments the root profile can be elongated, including linearly, in the axial reference plane.

In the illustrated embodiment, the consistent geometries of the primary flank portions75b,77bare linear, and define the head thread angle A6, which can be in a range of about 48 degrees to about 52 degrees, and can also be in a range of about 40 degrees to about 60 degrees, and can further be in a range of about 25 degrees to about 75 degrees. It should be appreciated that the primary flank portions75b,77bcan alternatively define consistent geometries that are non-linear, such as curved, including an involute curve, similarly as described above with reference toFIGS.2H and2I, or a curve having a constant, relatively large radius.

The head thread segments73define crest profiles76athat extend between the upper and lower crest reference points76-1,76-2. The crest profiles76acan be convex, and are preferably radiused, rounded, chamfered, beveled, or otherwise truncated and/or relieved for reducing stress concentrations along the crest profile76a. As depicted, the crest profile76acan define a relief radius R7, which can be in a range of about 0.01 mm to about 0.40 mm, and/or in a range of about 0.11 mm to about 0.13 mm, and/or in a range of about 0.07 mm to about 0.15 mm, and/or in a range of about 0.03 mm to about 0.18 mm. In such convex profiles, a crest tip reference point76-3is defined at the apex of the crest profile76a, as measured from the central screw axis23. The crest trajectory axis86intersects each of the crest tip reference points76-3. Additionally, the crest profiles76acan define respective crest widths W2, as measured between the upper and lower crest reference points76-1,76-2along a direction DP3oriented along the crest trajectory axis86at the crest tip reference point76-3. The crest width W2can be in a range of about 0.11 mm to about 0.15 mm, and/or in a range of about 0.08 mm to about 0.18 mm, and/or in a range of about 0.01 mm to about 0.20 mm. In some embodiments, the crest width W2is 0.10 mm or greater (i.e., no less than 0.10 mm). It should be appreciated that the foregoing geometries of the crest profiles76aare provided as non-limiting examples, and that other crest profile geometries are within the scope of the present disclosure, including linear crest profiles76a.

The screw head threads74define a head thread height H3measured from the crest76to the root78in the axial reference plane. In particular, the head thread height H3of any of the head thread segments73is measured between the root reference point78-1to the crest trajectory axis86, along a direction DP2perpendicular to that portion of the crest trajectory axis86. The head thread height H3can be in a range of about 0.05 mm to about 2.00 mm, and can also be in a range of about 0.10 mm to about 1.50 mm, and can also be in a range of about 0.11 mm to about 0.50 mm, and can also be in a range of about 0.24 mm to about 0.28 mm, and can also be in a range of about 0.20 mm to about 0.30 mm, and can further be in a range of about 0.12 mm to about 0.34 mm.

Similarly as described above with reference to the plate threads9, the thread profiles of the screw head threads29deviate from a reference cross-sectional thread profile (i.e., “reference profile”) that is V-shaped in the axial reference plane. This deviation from the reference profile of the screw head threads29causes the actual head thread height H3to be less than a theoretical maximum head thread height H4comprising un-truncated and/or un-relieved crests76and un-relieved roots78. This theoretical maximum head thread height H4can also be referred to herein as the “reference height” H4of the screw head threads29. The reference height H4of the screw head threads29is measured, in the axial reference plane, from a root reference axis88ato a crest reference axis86a, along direction DP2. The crest reference axis86aintersects reference points76-4, which are defined at the apices of the reference profile on a first side thereof. Also similarly, the root reference axis88aintersects reference points78-2, which are defined at apices of the reference profile on a second side thereof opposite the first side. The reference height H4of the screw head threads29represents the theoretical maximum head thread height should the primary upper and lower flank portions75b,77bextend from a un-truncated crest to an un-relieved root.

As above, the reference profile of the screw head threads29is defined by the actual thread profile of the screw head threads29, and has a thread pitch and thread lead equivalent to those of the screw head threads29. Additionally, the reference profile is coincident with the thread profile at least at one recurring location of each thread segment73in the axial reference plane. For example, as shown inFIG.3C, the reference profile can be coincident with each of the upper and lower flanks75,77at least at the second flank reference points75-2,77-2thereof, and also at each location along the linear primary flank portions75b,77b, including at reference points76-1and76-2. Thus, for linear primary flank portions75b,77b: each crest reference point76-4can also be defined by intersections of projections75c,77cof the upper and lower primary flank portions75b,77along their respective consistent geometries away from the central screw axis23; and each root reference point78-2can also be defined by intersections of projections75d,77dof the primary flank portions75b,77along their respective consistent geometries toward the central screw axis23.

Referring now toFIGS.4A and4B, the complimentary thread proportions described above can enhance the mechanical strength of the locked thread interface between the plate threads9and the screw head threads29. For example, the thread profile geometry of the dual-angle column threads54can provide an increased form-fit, particularly at angulated screw9insertion trajectories, such as that depicted inFIGS.4A and4B. Additionally, the axial space between the opposed flank profiles55a-c,57a-cprovides favorable clearance between the roots58of the plate threads9and the crests76of the screw head threads29. Such crest-to-root76-58clearance is particularly beneficial at angulated insertion trajectories because it prevents or at least reduces undesirable mechanical interference between the head crests76and the plate roots58. Additionally, the rounded crest profiles76aof the screw head threads29, particularly those having relatively large relief radii R7, effectively rounds or removes sensitive edges of the screw head threads29that could otherwise deleteriously mechanically interfere with plate threads9.

A further advantage provided by the thread proportions described herein is that a measure of control is provided over the thread deformation at the thread interface. In particular, by interfacing the stronger profile of the screw head thread segments73against the more malleable profile of the plate thread segments52, a vast majority of the thread deformation can be imparted to the plate threads9. At angulated screw9insertion trajectories, such controlled deformation can allow the plate threads9to deform so as to effectively re-align to the angulated central screw axis23. Such controlled deformation also provided enhanced locking with the angulated screw head27. After form-fit is achieved, further rotational advancement of the VA locking screw8with respect to the column threads54can commence deforming the one or more column threads54, preferably at the crests56, as shown at interference regions99inFIG.4B. This deformation occurs primarily radially outward, although some measure of axial and/or circumferential deformation can occur (mostly when a timing-error is present). Moreover, the radial deformation can include plastic and elastic deformation, which compresses the one or more column threads54in a manner exerting a reactive compressive force against the associated screw head threads29, primarily at the roots78thereof, achieving a locking press-fit with the screw head27. It is to be appreciated that the plate threads9are also axially deformable, which allows the plate threads9to deform axially downward or upward, such as when the VA locking screw8is inserted with timing error.

With respect to the foregoing aims of enhancing the mechanical strength of the locked thread interface and reducing cross-threading, particularly at of the screw head27at angulation, and also limiting cross-threading so that is occurs substantially entirely within the plate threads29and as an act of plastic and elastic thread deformation, the inventors have identified, through their own extensive testing, particularly effective parameters of the thread proportions discussed above. One such thread proportion parameter for the plate threads9and screw head threads29is the relationship between the actual thread height H1, H3versus the reference height H2, H4. For example, the plate threads9, particularly the column threads54, define a plate thread height factor (“HF-P”), which is calculated as a ratio of the actual thread height H1to the reference height H2of the column threads54(i.e., (HF-P)=H1/H2). The plate thread height factor (HF-P) is preferably in a range of about 0.50 to about 0.60, and can also be in a range of about 0.40 to about 0.75, and can further be in a range of about 0.30 to about 1.00. Similarly, the screw head threads29define a screw head thread height factor (“HF-S”), which is calculated as a ratio of the actual thread height H3to the reference height H4of the screw head threads29(i.e., (HF-S)=H3/H4). The screw head thread height factor (HF-S) is preferably in a range of about 0.63 to about 0.67, and can also be in a range of about 0.55 to about 0.75, and can further be in a range of about 0.40 to about 0.90. The screw head thread height factor (HF-S) is preferably combined with a rounded crest profile76ahaving a relatively large crest width W2, as well as a relatively large relief radius R7, such as the values of W2and R7described above.

Additionally, the plate threads9(particularly the column threads54) and the screw head threads29can define a comparative height factor (“CHF”), which is calculated herein as a ratio of the actual thread height H1of the plate threads9to the actual thread height H3of the screw head threads29(i.e., CHF=H1/H3). The comparative height factor (CHF) is preferably in a range of about 1.58 to about 1.62, and can also be in a range of about 1.30 to about 1.90, and can further be in a range of about 1.00 to about 2.00.

In combination with the foregoing values recited for the plate thread height factor (HF-P), the screw head thread height factor (HF-S), and the comparative height factor (CHF), the inventors have discovered through their extensive testing that particularly favorable thread deformation occurs when plate thread angle A4is in a range from 25 degrees to 35 degrees and the head thread angle A6is in a range from 45 degrees to 60 degrees, including the multi-angle embodiments where A4is the first thread angle of the plate threads9. The inventors have discovered, surprisingly and unexpectedly, that the foregoing combination of parameters can cause most if not substantially all of the thread deformation at the locking interface between the plate threads9and screw head threads29to occur within the plate threads9. Stated differently, the inventors have discovered a particular combination of thread parameters that effectively cause the screw head threads29to plastically deform the plate threads9substantially without being plastically deformed themselves.

It is to be appreciated that the designs of the VA locking holes6and the screw head27, including the thread proportion parameters thereof, can be adjusted while remaining within the scope of the present disclosure. For example, additional embodiment of the VA locking hole6will now be described with reference toFIGS.5A through9D. The VA locking holes6of these additional embodiments are generally similar to the VA locking hole6described above with reference to the preceding embodiment described above with reference toFIGS.2A through2G. Accordingly, like reference numbers from the preceding embodiment will also be used in these additional embodiments. Moreover, it should be appreciated that, for the sake of brevity, the following disclosure will focus primarily on the differences between the VA locking holes6of these additional embodiment and the preceding embodiment.

Referring now toFIGS.5A through5D, an additional embodiment of the VA locking hole6is shown having, among other things, a thinner thread profile and larger recesses28than those of the preceding embodiment. As shown inFIG.5A, the recesses28of the present disclosure define a recess radius R10greater than that of the preceding embodiment, such that the recesses28of the present embodiment each have a horizontal profile that subsumes a majority of a circle. Accordingly, at least a portion of the first and second sides44,45of each threaded column26, particularly the portions contiguous with the first surface42, can taper toward each other. As depicted, the VA locking hole6of the present embodiment can have three (3) threaded columns26and three (3) recesses28sequentially located circumferentially between the columns26, although the present embodiment can have fewer than three (3) or more than three (3) columns26and recesses28. As shown inFIG.5B, the hole6can also have a first lead in surface34athat is steeper than the lead in surface34of the preceding embodiment. A second, lower lead in surface34bcan be contiguous with the first lead in surface34a, an can be oriented at a shallower angle relative to the first lead in surface34a.

Referring now toFIGS.5B and5C, as above, the crests56of the column threads54extend along the crest trajectory axis46, and the roots58of the column threads extend along the root trajectory axis48. Also, the column threads54define a thread angle A4measured between the upper flank55and the lower flank57of a thread segment52. In addition to having thinner profiles, the column threads54of the present embodiment define a single thread angle A4, which can be in a range of about 25 degrees to about 35 degrees, and can also be in a range of about 20 degrees to about 50 degrees, and can further be in a range of about 15 degrees to about 75 degrees. The column threads54of the present embodiment define a thread height H1and a reference height H2. As above, the thread height H1represents the actual thread height of the column threads54, while the reference height H2represents the theoretical maximum thread height comprising un-truncated crests56and un-relieved roots58. At any of the thread segments52, the thread height H1is measured from the crest trajectory axis46to the root58along the direction DP1perpendicular to the crest trajectory axis46, while the reference height H2is measured from the crest reference axis46ato the root reference axis48aalong direction DP1.

As shown inFIG.5C, the roots58of the present embodiment define elongated root profiles58athat extend linearly along the root trajectory axis48, which increases the total area between the opposed flanks55,57. This increases area between the flanks55,57, in combination with the thinner thread profiles, allows the column threads54to have beneficial malleability (and thus deformability) when engaged with the screw head threads29. Furthermore, with reference to a radially inward direction, the profile of the upper flank55includes:a) a first upper flank portion55a(or upper “root relief” portion55a) that extends from a first upper flank reference point55-1to a second upper flank reference point55-2;b) a second or “primary” upper flank portion55bthat extends along a consistent geometry from the second upper flank reference point55-2to a third upper flank reference point55-3; andc) a third upper flank portion55c(or upper “crest relief” portion55c) that extends from the third upper flank reference point55-3to a lower crest reference point56-1.
Similarly, with reference to the radially inward direction, the profile of the lower flank57includes:a) a first lower flank portion57a(or lower “root relief” portion57a) that extends from a first lower flank reference point57-1to a second lower flank reference point57-2;b) a second or primary lower flank portion57bthat extends along a consistent geometry from the second lower flank reference point57-2to a third lower flank reference point57-3; andc) a third lower flank portion57c(or lower “crest relief” portion57c) that extends from the third lower flank reference point57-3to an upper crest reference point56-2.
In the present embodiment, the root profile58aextends from an upper root reference point58-1, which is coincident with the first upper flank reference point55-1, to a lower root reference point58-2, which is coincident with the first lower flank reference point57-1. As before, the upper and lower root relief portions55a,57acan each be arcuate and define a root relief radius for reducing reduce stress concentrations at the root58. The root relief radius R5can optionally be the same (i.e., common) for the upper and lower root relief portions55a,57a. It should be appreciated that the root relief radius R5of the plate threads9can optionally be substantially equivalent to the crest relief radius R7of the screw head threads29. Additionally, in the present embodiment, the upper and lower crest relief portions55c,57ccan be arcuate and define a crest relief radius for reducing stress concentrations at the crest56. As shown, one or more of the thread segments52of the present embodiment can have a primary flank profile portion55b,57bthat extends to the respective upper or lower crest reference point56-1,56-2. Stated differently, one or more of the crests56need not have both upper and lower crest relief portions55c,57c. Moreover, as above, a transition portion, which can be arcuate, can optionally extend between the primary flank portions55b,57band the respective third upper and lower flank portions55c,57cof any and up to all of the profiles flanks55,57.

As above, the crest reference axis46aintersects crest reference points56-3of the reference profile, and the root reference axis48aintersects root reference points58-3of the reference profile. Also similarly as described above, when the primary flank portions55b,57bare linear, the crest reference points56-3and the root reference points58-3can also be defined by respective intersections of the projections55d,57dand55e,57eof the primary flank portion55b,57balong their consistent geometries.

In the present embodiment, the thread height H1can be in a range substantially equivalent to that described above with reference toFIG.2G. Additionally, the plate thread height factor (HF-P) of the present embodiment can be in a range of about 0.36 to about 0.40, and can also be in a range of about 0.34 to about 0.70, and can further be in a range of about 0.30 to about 1.00. It should be appreciated that the elongated root profile58aof the present embodiment effectively moves the root reference axis48afurther away from the central hole axis22relative to the preceding embodiment, which can also reduce the plate thread height factor (HF-P) relative to the preceding embodiment.

Referring now toFIG.5D, the thinner thread profiles of the present embodiment can also provide enhanced locking with the VA screw head27, including advantageous thread deformation and enhanced mechanical locking strength, compared to prior art thread designs. Although the column threads54of the present embodiment might not provide as much radial clearance between the column thread roots58and the crests76of the screw head threads29as the preceding embodiment, the thinner profiles of the column threads54of the present embodiment can allow the column threads54to deform more readily upon engagement with the screw head threads29, including at angulated screw insertion trajectories. For example, as shown inFIG.5D, at angulation (such as an angulation A1of about 15 degrees), the column threads54can deform favorably in the radial direction R (as well as along direction DP1) at their crests56and flanks55,57responsive to engagement with the screw head threads29at interference region99. Additionally, the upper and lower flanks55,57of the column threads54are generally positioned at complimentary orientations with the upper and lower flanks75,77of the screw head threads29at angulation, which provides a beneficial form fit at angulation. As above, by interfacing the stronger profiles of the screw head thread threads29against the thinner, malleable profile of the column threads54of the present embodiment, the vast majority of the thread deformation can be imparted to the plate threads9, allowing the plate threads9to deform so as to effectively re-align to the angulated central screw axis23. Additionally, the foregoing deformation, as above, occurs primarily radially outward, although some measure of axial and/or circumferential deformation can occur (mostly when a timing-error is present).

Referring now toFIGS.6A and6B, in additional embodiments, the VA locking hole6, or at least an axial portion thereof, can have a horizontal hole profile that is non-circular. By way of non-limiting example, at least an axial portion of the hole6can have a generally polygonal horizontal hole profile. In particular, the present embodiment of the VA locking hole6is shown having a trigon (i.e., generally triangular) horizontal profile, although other polygonal shapes are within the scope of the present disclosure. The interior surface24of the plate body5within the hole6, or at least an axial portion thereof, defines a corresponding non-circular (e.g., trigon) horizontal profile. Additionally, plate threads9extend along a thread path that has a corresponding non-circular (e.g., trigon) horizontal profile. Moreover, one or more and up to each of the upper perimeter30, the one or more lead in surfaces34, the one or more undercut surfaces36, and the lower perimeter32of the hole6can also have corresponding non-circular (e.g., trigon) horizontal profiles.

In the illustrated embodiment, the first surfaces42of the columns26have linear horizontal profiles. In other embodiments, one or more of the first surfaces42can have arcuate profiles having a relatively large radii. In either of such embodiments, the first surfaces can tangentially intersect a reference circle43centered at the central hole axis22. In particular, the first surfaces42can intersect the reference circle43substantially at the crest trajectory axis46. Is should be appreciated that the reference circle43illustrates the hole's departure from a circular horizontal profile. The reference circle43inFIG.6Bis shown intersecting an axially lowermost one of the first surfaces42within the polygonal hole6, at which axial location the reference circle43also illustrates the minimum diameter within the hole6(and thus also the minimum minor diameter of the plate threads9). The reference circle43defines a radius R8, which, for the depicted reference circle43, is equivalent to one-half (½) the minimum minor thread diameter of the hole6. For the depicted reference circle43, the radius R8can be in a range of about 2.0 mm to about 2.1 mm, and can also be in a range of about 1.8 mm to about 2.5 mm. In additional embodiments, including those for use with VA locking screws8with screw shafts25having a major diameter in the ranges listed above with reference toFIG.1A(i.e., ranges of about 0.5 mm to about 10.0 mm, about 1.0 mm to about 7.0 mm, about 2.0 mm to about 4.0 mm, and more particularly a major diameter of about 3.5 mm), radius R8can be in a range of about 0.5 mm to about 15.0 mm, more particularly in a range of about 1.0 to about 10.0 mm, more particularly in a range of about 1.0 mm to about 5.0 mm, more particularly in a range of about 1.5 mm to about 5.0 mm, and more particularly in ranges of about 2.0 mm to about 4.0 mm, about 0.5 mm to about 3.5 mm, about 1.8 mm to about 2.5 mm, and about 2.0 mm to about 2.1 mm. It should be appreciated that radius R8can optionally be used as a metric for categorizing the size of the hole6(for example, as an alternative of, or in addition to any of the mean crest radius R2, the mean radius R3, and the mean root radius R4described above). As above, the first surface42of each column26extends between a first side44and a second side45, which sides44,45define interfaces between the column26and the circumferentially adjacent recesses28. In the present embodiment, however, the recesses28extend tangentially from the first and second sides44,45of the associated columns26. In this manner, the first surfaces42of the columns26effectively define the sides of the trigon, while the recesses28effectively define the corners of the trigon, each as viewed in the horizontal reference plane. Accordingly, the columns26and recesses28of the present embodiment can also be referred to respectively as “sides” and “corners”28of the trigon-shaped hole6. Each of the corners28can define a corner radius R9, measured from the corner axis37to the corner apex39. The corner radii R9can be in a range from about 0.0 mm to marginally smaller than R8and further to about R8. The crests56and roots58of the plate threads9extend along respective splines that revolve about the central hole axis22helically along the trigon profile of the interior surface24between the upper plate surface18and the lower plate surface20. Additionally, the interior surface24, including the columns26as well as the corners28, tapers inwardly toward the central hole axis22from the upper plate surface18toward the lower plate surface20. Moreover, as shown, the plate threads9can circumferentially traverse the columns26and the corners28in an uninterrupted fashion (i.e., the plate threads9need not bottom-out in the corners28). Accordingly, the plate threads9can transition smoothly and continuously between the column threads54and the portions of the threads9that traverse the corners28.

The first surfaces42of each column26define a column length LC measured between the sides44,45of the column26. In the present embodiment, the column length LC can be substantially consistent within each column26as the thread path advances between the upper and lower surfaces18,20of the plate4. In such embodiments, the column length LC can also be referred to as a “side length” LC of the trigon-shaped hole6. The columns26of the present embodiment can have substantially equivalent column lengths LC, thus providing the hole6with a substantially equilateral triangular shape, as shown. The column length LC can be in a range from about 0.010 mm to about 4.00 mm, and more particularly in a range from about 0.25 mm to about 3.25 mm, and more particularly in a range of about 0.50 mm to about 2.85 mm. For example, in a preferred embodiment, the column length LC can be in a range from about 0.20 mm to about 0.35 mm. In another embodiment, the column length LC can be in a range from about 0.50 mm to about 0.60 mm, and preferably in a range of about 0.530 mm to about 0.570. Alternatively, the column lengths LC of two or all of the columns can differ from one another. In further embodiments, the column length LC of one or more and up to all of the columns26can successively increase as the thread path advances from the upper surface18toward the lower surface20of the plate4, thereby causing the corner radii R9to progressively decrease toward the lower surface20of the plate4.

Referring now toFIG.6C, the plate threads9of the present embodiment can have a substantially consistent thread profile and thread height H1as the threads9revolve along their thread path(s) about central hole axis22, including along one or more revolutions. Thus, the thread height H1can be substantially equivalent at the crest centerlines46of the columns26and at the corner apices39, and also at the portions of the columns26and corners28therebetween. As shown inFIG.6C, the corner apices39can be defined along the crests56of the threads9, and a corner root axis39acan extend linearly in a manner intersecting the roots58of the threads9. At the corner apex39, the thread height H1is measured between the crest56(or the corner apex39) and the root58(or the corner root axis39a) along a direction DP4perpendicular to the corner apex39. In the present embodiment, each corner apex9and corner root axis39ashares a common axial plane with the crest trajectory axis46and root trajectory axis48of an opposed one of the columns26. Thus, with respect to the thread profile, the recess apex39is analogous to the crest trajectory axis46, while the corner root axis39ais analogous to the root trajectory axis48. Accordingly, the crest trajectory axis46and the corner apex39can each be oriented at angle A2described above, while the root trajectory axis48and the corner root axis39acan each be oriented at angle A3described above.

Moreover, the plate threads9of the present embodiment can also define a helical series of thread segments52having substantially consistent thread profiles along the thread path(s), including at the crest centerlines46, at the corner apices39, and locations circumferentially therebetween. In particular, the crests56, roots58, and upper and lower flanks55,57of the threads9of the present embodiment can each have substantially consistent profiles along the thread path(s). It is to be appreciated that, in the present embodiment, the crests56can define crest profiles56a, the roots can define root profiles58a, and the upper and lower flanks55,57can define respective upper and lower flank profile portions55a-c,57a-c(including optional transition portions), each in a similar manner as those described above with reference toFIG.2G. Accordingly, the threads9at the columns26and corners28can be multi-angle threads, including dual-angle threads, particularly with first and second thread angles A4, A5as described above. Alternatively, as shown inFIGS.16A through16H, the plate thread profiles of the trigon-shaped VA locking hole can be configured similarly to the single-angle threads described above with reference toFIGS.5B through5D, or can include arcuate thread profiles as described above with reference toFIGS.2H and2I. Moreover, the thread segments52of the column threads54also define a reference thread height H2measured between a crest reference axis46aand a root reference axis48a, which are also defined in the manner described above with reference toFIG.2G. It should be appreciated that the threads9of the corners28also define a reference height H2, which, at the corner apex39, is measured along direction DP4between an un-truncated crest reference point and an un-relieved root reference point, which are defined by the thread profiles at the corners in an analogous manner as described above with reference toFIG.2G. It should also be appreciated that the thread height H1and reference thread height H2can be substantially equivalent at the columns26and corners, respectively, and can also be within the respective ranges described above.

It is to be appreciated that the trigon-shaped VA locking hole6described above increases the total contact area between the plate threads9and the screw head threads29, while also providing the plate threads9, particularly the column threads54thereof, with a measure of the favorable deformation qualities described above. In this manner, the locking interface of the plate threads9and screw head threads29can provide the locking screw8with an overall cantilever strength (i.e., resistance to a force applied perpendicularly to the central axis23of the screw8) greater than that of the preceding embodiments, while also causing most if not substantially all of the thread deformation at the locking thread interface to be imparted plastically and elastically to the plate threads9. The inventors have discovered, surprisingly and unexpectedly, through their own extensive testing, that the plate threads9of the present embodiment and the screw head threads27described above have a locking thread interface that, at certain angulations, has a cantilever strength that approaches and can even exceed the ultimate bending strength of the screw8. For example, the inventors' tests have shown that a VA locking screw8, configured as described above and fully seated in the VA locking hole6of the present embodiment at an angulation from nominal to about 6 degrees, will fail (i.e., break, or bend to an extent categorized as failure of a VA locking screw) at a location of the screw shaft25proximate the distal end72of the head27. Stated differently, at the foregoing conditions, the screw shaft25will fail before the locking thread interface fails. Moreover, at a fully seated insertion at angulations in a range from about 6 degrees to about 15 degrees, the cantilever strength of the locking thread interface decreases to within a range of about 30 percent to 40 percent of the ultimate bending strength of the screw8. These cantilever strengths of the locking thread interface, particularly at angulation, represent significant improvements over prior art VA locking hole-screw systems.

Referring now toFIGS.7A and7B, in further embodiments, the corner radii R9of the polygonal-shaped (e.g., trigon-shaped) VA locking hole6can be reduced and the column length LC (i.e., the length of the first surfaces42of the thread columns26, as measured between the sides44,45) can be increased relative to the hole6shown inFIGS.6A through6C, thereby providing the polygonal hole6of the present embodiment with sharper corners28, and thus a more profound polygonal (e.g., triangular) shape. Accordingly, the plate threads9, and thus the crests56and roots58thereof, can extend along a thread path that also has a more profound triangular shape as it traverses the columns26and corners28. The other parameters of the trigon-shaped hole6can be maintained as described above with reference toFIGS.6Athrough6C, including the radius R8of the reference circle43, the axial taper angles A2, A3, the thread profiles, the thread angles A4, A5, the thread height H1, and the reference height H2. Alternatively, one or more of these other parameters can be adjusted as needed.

It is to be appreciated that reducing the corner radii R9and increasing the length of the first surfaces42of the polygonal-shaped VA locking hole6effectively distributes forces between the plate threads and the screw head threads29in a more tangential manner relative to the force distribution of the polygon-shaped locking hole6described above with reference toFIGS.6A through6C.

Referring now toFIGS.8A and8B, in additional embodiments, the VA locking hole6can have a polygonal horizontal profile in the shape of a tetragon (i.e., a four-sided polygon). Accordingly, the interior surface24of the plate body5within the hole6defines a corresponding tetragon horizontal profile. Additionally, the upper perimeter30, the one or more lead in surfaces34, the one or more undercut surfaces36, and the lower perimeter34of the hole6preferably can also have corresponding tetragon horizontal profiles.

As in the polygonal-shaped holes described above, the first surfaces42of the columns26have linear horizontal profiles that tangentially intersect the reference circle43. In particular, each of the first surfaces42intersects the reference circle43substantially at the crest trajectory axis46. The radius R8of the reference circle43can be within the ranges described above. The corners28extend tangentially from the first and second sides44,45of each column26, such that the first surfaces42define the sides of the tetragon extending between the corners28. In the present embodiment, the corner radii R9can be in any of the ranges described above with reference toFIGS.6A through7C.

In the present embodiment, the length of the first surfaces42, and thus the distance between the sides44,45of each column26, can successively increase as the thread path advances toward the lower surface20of the plate4. Accordingly, the respective engagement forces between the plate threads9and the screw head threads29can be progressively distributed in a more tangential manner as the screw head27advances within the hole6, including at an angulated insertion trajectory. Alternatively, the first surfaces42of each column26can have a substantially consistent length along the thread path.

Similar to the manner described above, the crests56and roots58of the plate threads9extend along respective splines that revolve about the central hole axis22helically along the tetragon profile of the interior surface24between the upper plate surface18and the lower plate surface20. Additionally, the interior surface24, including the columns26as well as the corners28, tapers inwardly toward the central hole axis22from the upper plate surface18toward the lower plate surface20. Moreover, as shown, the plate threads9can circumferentially traverse one or more an up to each of the corners28in an uninterrupted fashion (i.e., the plate threads9need not bottom-out in the corners28).

Referring now toFIG.8C, the plate threads9of the present embodiment can define thread profiles similar to those described above with reference toFIG.2G, as well as with reference to the trigon-shaped VA locking holes6. Moreover, it should be appreciated that the thread profiles, including the crest56, roots58, and flanks55,57thereof, can be substantially consistent along the thread path, including at the columns26and at the corners28, as described above with reference to the trigon-shaped holes6. Accordingly, the threads9can have a substantially consistent thread height H1, as well as a substantially consistent reference height H2, along the thread path(s). The thread height H1and reference height H2can be defined as described above.

As with the trigon-shaped VA locking holes6described above, the tetragon-shaped holes6of the present embodiment effectively increase the total contact area between the plate threads9and the screw head threads29, while also providing the threads9with a measure of the favorable deformation qualities described above. In this manner, the locking thread interface of the tetragon-shaped hole6can exhibit an overall cantilever strength greater than that of the embodiments described above with reference toFIGS.2A through2G and4A through5D.

It should be appreciated that the VA locking holes6of the present disclosure can have other polygonal horizontal profiles, including pentagonal (i.e., five sides42and five corners28), hexagonal (i.e., six sides42and six corners28), heptagonal (i.e., seven sides42and seven corners28), octagonal (i.e., eight sides42and eight corners28), nonagonal (i.e., nine sides42and nine corners28), decagonal (i.e., ten sides42and ten corners28), etc., up to a number of sides42that substantially defines a circular horizontal hole profile. It should also be appreciated that in any of the polygonal-shaped VA locking holes6of the present application, the threads9can extend in continuous and un-interrupted fashion along the columns26and corners28, or optionally the threads9can bottom-out in the corners28. Moreover, the thread profiles in any of the non-circular (e.g., polygonal-shaped) VA locking holes6of the present application can be single-angle (e.g., similar to that described above with reference toFIGS.5B through5D), dual- or additional multi-angle, or arcuate, as described above.

In further embodiments, the VA locking holes6of the present disclosure can have a horizontal hole profile according to any of the shapes described above, wherein the horizontal hole profile itself revolves about the central hole axis22from the upper plate surface18toward the lower plate surface20, thereby defining a twisted or spiraling hole profile geometry. Moreover, the VA locking holes6of the present disclosure can extend obliquely through the bone plate4, such that the central hole axis22is oriented at a non-orthogonal angle relative to one or both of the upper plate surface18and the lower plate surface20. Furthermore, the upper and lower plate surfaces18,20of the bone plate4, or at least portions thereof, need not be flat, but can instead be bent, contoured, textured, roughened, dimpled, bulgy, or have any other geometry for providing an enhanced interface or fit with the anatomy of the underlying bone. In additional embodiments, the VA locking holes6of the present disclosure can have multiple horizontal hole profiles (i.e., hole shapes) along the central hole axis22. For example, the internal surface24within any of the VA locking holes6can optionally include at least a first axial portion adjacent the upper plate surface18and defining a first horizontal hole profile and at least a second axial portion extending axially between the first axial portion and the lower plate surface20and defining a second horizontal hole profile that is different than the first horizontal hole profile. By way of one non-limiting example, the first axial portion of the interior surface24can extend from the upper perimeter30of the hole6and can include the lead-in surface(s)34and the threads9having a fully-developed thread-form, while the second axial portion of the interior surface24can include the undercut surface36and can extend to the lower perimeter32of the hole6. The first axial portion can have any of the circular or non-circular horizontal profiles described herein (including any of the polygonal profiles), while the second axial portion can have any of the foregoing profiles that is different than the first axial portion. In such multi-profile hole embodiments, the interior surface24can also include a transition portion between the first and second axial portions, in which the horizontal hole profile transitions between the first and second horizontal hole profiles. It should be appreciated that the interior surface24can also include one or more additional axial portions each having a horizontal hole profile that is different than at least one other of the horizontal hole profiles within the VA locking hole6.

Furthermore, as mentioned above, the design of the VA locking hole6is not limited by the number of columns and recesses or corners28. Accordingly, by way of a non-limiting example, the hole6can have three (3) columns26circumferentially spaced between three (3) recesses28, as shown inFIG.9. Moreover, the hole6can alternatively have more than four (4) each of columns26and recesses28. In further embodiments, the VA locking hole6can have five (5), six (6), seven (7), eight (8), nine (9), ten (10), eleven (11), twelve (12), thirteen (13), fourteen (14), fifteen (15), sixteen (16), or more than sixteen (16) each of columns16and recesses28. By way of another non-limiting example,FIG.10shows a VA locking hole6having eight (8) columns26circumferentially spaced between eight (8) recesses28. Additionally, as shown, the recesses28can define central recess axes37that are oriented at an acute angle A9with respect to the central hole axis22. In such embodiments, the angle A9can be substantially equivalent to the angle A2at which the crest trajectory axis46is oriented, as described above with reference toFIG.2E.

It should also be appreciated that any of the VA locking holes6described above, including any features thereof (such as the thread geometries, by way of a non-limiting example), can be incorporated into a combination hole (also referred to as a “combi-hole”) with another hole, such as a compression hole, within the bone plate4. With reference toFIGS.11A through15B and17through20, embodiments of a combi-hole90will be described in which the VA locking hole6portion thereof is trigon-shaped, similar to the embodiments described above with reference toFIGS.6A through7B.

Referring now toFIGS.11A and11B, one example of such a combi-hole90includes a compression hole92in combination with the VA locking hole6, such that the VA locking hole6and the compression hole92overlap one another and are open to each other. In this manner, interior surface24of the plate body5can define both the VA locking hole6and the compression hole92, each extending from the upper plate surface18to the lower plate surface20. An upper perimeter30of the combi-hole90can define an upper opening to each of the VA locking hole6and the compression hole92. Similarly, a lower perimeter32of the combi-hole90can define a lower opening to each of the VA locking hole6and the compression hole92. It should be appreciated that the VA locking hole6and the compression hole92can be referred to as respective “portions” of the combi-hole90can each be referred to as a respective “hole.” Moreover, the portion of the interior surface24that defines the VA locking hole6can be referred to as a first or “locking” surface24a. Similarly, the portion of the interior surface24of the combi-hole90that defines the compression hole92can be referred to as a second surface24b. The locking surface24acan define one or more lead-in surfaces34that taper axially downward from the upper perimeter30to plate threads9in the VA locking hole6.

The second surface24bcan define a compression surface96of the compression hole92. At least a portion up to an entirety of the compression surface96can be unthreaded. Accordingly, the compression surface96defines a bearing surface against which the unthreaded compression head of a compression screw is configured to bear so as to apply a compressive force against the bone plate4toward the underlying bone. In one example, the compression surface96can be concave in the axial direction with respect to a central hole axis94of the compression hole92. For instance, the compression surface96can be dish shaped or semi-spherical. Alternatively, the compression surface96can have a linear profile that tapers radially inwardly toward central hole axis94from the upper plate surface toward the lower plate surface20. The locking surface24acan define a first undercut surface36athat tapers axially upward from the lower perimeter32of the combi-hole90to the plate threads9. The second surface24bcan define a second undercut surface36bthat tapers axially upward from the lower perimeter32to the compression surface96.

Referring now toFIGS.11C and11D, in the combi-hole90, the VA locking hole6and the compression hole92can be open to each other along a direction X1, which is preferably oriented along an intersection axis97that intersects the central hole axis22of the VA locking hole6and a central hole axis94of the compression hole92. Direction X1can be referred to as the “longitudinal hole direction” X1and can be oriented along the longitudinal direction X of the plate4, or along any suitable alternative direction as desired. The compression hole92can be elongate along the longitudinal hole direction X1. For example, the compression hole92can have a horizontal hole profile that is substantially elliptical. In such embodiments, the intersection axis97can be coextensive with the major axis of the elliptical horizontal hole profile. Moreover, the central axis94of the compression hole90can be located at a midpoint between the foci of the elliptical horizontal hole profile. The combi-hole90defines a first axis separation distance LA1between the central axes22,94of the VA locking hole6and the compression hole92along the longitudinal hole direction X1. It should be appreciated that the compression hole92can have non-elliptical horizontal hole profiles in other embodiments. For example, the compression hole92can have a circular horizontal hole profile. As shown inFIG.17, the combi-hole90can optionally have a compression hole92having semi-circular ends and elongate sides96aextending therebetween along the longitudinal hole direction X1, or similar such geometries.

For purposes of this disclosure, the central axis94of the compression hole92extends through the geometric midpoint of a theoretical completed version of the compression hole92. Stated differently, central axis94extends through what could be considered the geometric midpoint of the compression hole92if the compression hole92were not interrupted by the VA locking hole6. The intersection axis97can also intersect a midpoint46of a first of the columns or “sides”26aof the trigon VA locking hole6. Stated differently, the intersection axis97can intersect the crest centerline46of the first column26aof the trigon VA locking hole6, which column26acan be referred to as the “base” column26a. In such embodiments, the second and third columns26b,26cof the trigon VA locking hole6can be equidistantly spaced from the intersection axis97along a lateral hole direction Y1oriented perpendicular to the longitudinal hole direction X1. The locking surface24aand the second surface24bcan intersect one another along an intersection boundary119. In particular, a first portion of the intersection boundary119on a first side of the intersection axis97is separated from a second portion of the intersection boundary119on a second side of the intersection axis97by a gap124(FIG.11C) that is open to the trigon VA locking hole6and the compression hole92. The gap124defines a minimum gap distance G (FIG.11D) measured along the lateral hole direction Y1. The interior surface24can also define a hole intersection zone120in which the intersection boundary119is located.

Referring now toFIGS.11E and11F, the intersection boundary119can be defined by interface edges122between the locking surface24aand the second surface24b. In particular, the interface edges122include edges between the plate threads9and the compression surface96, which edges122tend to be abrupt and/or sharp as a result of the process(es) by which the combi-hole90is formed. Accordingly, the interior surface24within the hole intersection zone120is preferably adapted to reduce the abruptness and/or sharpness of the interface edges122to avoid, minimize, or at least reduce contact between such abrupt and/or sharp edges122of the plate threads9and surfaces of the screw head27, such as the described screw head threads29. One way to achieve this is to truncate, chamfer, bevel, or otherwise trim the interior surface24within the hole intersection zone120to define relief surfaces126therein. The relief surfaces126can be planar and can be parallel with the intersection axis97, although other relief configurations are within the scope of the present disclosure.

The interface edges122can be spaced from a reference point along the central axis22, such as an axial midpoint22athereof between the upper and lower surfaces18,20of the plate4. The axial midpoint22acoincides with the location at which the central axis22intersects a reference plane M that is orthogonal to the central hole axis22and located at the vertical center of the VA locking hole6, similarly as described above with reference toFIG.2E. Thus, the axial midpoint22ais located at what could be considered the geometric midpoint of the VA locking hole6if it weren't intersected by the compression hole92. The VA locking hole6can define a minimum straight line distance D1between the axial midpoint22aand the nearest interface edge122of the plate threads9, which in the present embodiment can be located at a crest56or, for example, at an upper flank55near a crest truncated by a relief surface126. Thus, the relief surfaces126can be configured to increase the minimum straight line distance D1to the intersection boundary119. The VA locking hole6can also define a maximum straight line distance D2between the axial midpoint22aand the furthest interface edge122of the plate threads9, which in the present embodiment can be located at a root58adjacent the lead-in surface34. AlthoughFIG.11Edepicts the intersection boundary119on only one lateral side of the combi-hole90, it should be appreciated that the minimum and maximum straight line distances D1, D2can be substantially similar at the intersection boundary119on the other lateral side of combi-hole90(i.e., the opposite side across the gap124along lateral hole direction Y1, as shown inFIG.11C).

One of the challenges of providing a combi-hole90that incorporates the trigon VA locking holes6of the present disclosure is providing sufficient threaded engagement between the screw head threads29and plate threads9within the hole intersection zone120while also minimizing contact between the screw head27(particularly the screw head threads29thereof) and sharp edges of the plate threads9(particularly the interface edges122thereof), especially when the screw head27is angulated into the hole intersection zone120and thus also into the gap124. Such an angulation A1of about 15 degrees between the screw axis23and the central axis22of the trigon VA locking hole6is indicated inFIG.11F. It should be appreciated that, alternatively or in addition to the relief surfaces126, the combi-hole90geometry can be further adapted to avoid, minimize, or at least reduce contact between abrupt and/or sharp edges122of the plate threads9and the screw head27while also providing sufficient threaded engagement at high angulation A1into the gap124.

Referring now toFIG.11G, a discussion of such adaptations to the combi-hole90geometry can be assisted with reference to a reference triangle RT shown in dashed lines intersecting the reference circle43described above at the respective locations at which the reference circle43intersects the plate threads9and/or the crest trajectory axes46(seeFIGS.6B and7B). The trigon VA locking hole6of the present embodiment is substantially equilateral, i.e., the columns26have substantially equidistance side lengths LC and the corners28have substantially equidistant corner radii R9. Accordingly, the reference triangle RT has first, second, and third sides S1, S2, S3that are substantially equilateral and extend between first, second, and third vertices V1, V2, V3that define respective angles AV1, AV2, AV3each being about 60 degrees. The first vertex V1is located opposite the first column26a, the second vertex V2is located opposite the second column26b, and the third vertex V3is located opposite the third column26c. For purposes of the following disclosure: the first side S1intersects the reference circle43tangentially at the same location at which the first surface42of the first column26aintersects the reference circle43; the second side S2intersects the reference circle43tangentially at the same location at which the first surface42of the second column26bintersects the reference circle43; and the third side S3intersects the reference circle43tangentially at the same location at which the first surface42of the third column26cintersects the reference circle43. The combi-hole90of the present embodiment is configured such that the first vertex V1is substantially coincident with the central axis94of the compression hole92, although in other embodiments the first vertex V1can be offset from the central axis94of the compression hole92. It should be appreciated that the central axes22,94of the combi-hole90can be parallel (as shown), although they need not be parallel.

Exemplary dimensions for the combi-holes90of the present disclosure will now be described, particularly for a subset of combi-holes90configured to receive locking screws8having shafts25with major diameters from about 0.5 mm to about 10.0 mm, more particularly from about 1.0 mm to about 7.0 mm, and more particularly in a range from about 2.0 mm to about 4.0 mm, and preferably about 3.5 mm. It should be appreciated that the following dimensions are provided for exemplary purposes, and that these combi-hole sizes can be scaled upward or downward in size as needed depending on the desired medical treatment. The radius R8of the reference circle43can be in a range from about 0.40 mm to about 5.50 mm, more particularly in a range from about 1.00 mm to about 3.00 mm, and more particularly in a range from about 1.40 mm to about 2.00 mm. The first axial separation distance LA1can be in a range from about 0.80 mm to about 10.00 mm, and more particularly in a range from about 2.00 mm to about 5.00 mm, and more particularly in a range from about 3.00 mm to about 4.00 mm. The corner radii R9can be in a range from about 0.20 mm to about 4.50 mm, and more particularly in a range from about 0.50 mm to about 2.00 mm, and more particularly in a range from about 0.75 mm to about 1.60 mm. The distance R1between the central axis22and the corner axes37of the trigon VA locking hole6can be in a range from about 0.01 mm to about 3.50 mm, and more particularly in a range from about 0.15 mm to about 0.75 mm, and more particularly in a range from about 0.300 mm to about 0.325 mm. The column lengths LC can be in a range from about 0.01 mm to about 4.00 mm, and more particularly in a range from about 0.25 mm to about 3.25 mm, and more particularly in a range from about 0.50 mm to about 2.85 mm.

According to one non-limiting example of the present embodiment, the radius R8of the reference circle can be about 2.050 mm, the first axial separation distance LA1can be in a range from about 4.0 mm to 4.8 mm, the corner radii R9of each corner28a-ccan be about 1.95 mm, the distance R1between the central axis22and the corner axes37of the trigon VA locking hole6can be about 0.142 mm, and the first surfaces42a-cof the columns26a-care each linear and have column lengths LC of about 0.2 mm to about 0.35, and more particularly from about 0.274 mm to about 0.276 mm. As shown, the hole intersection zone120can be located along the second corner28bof the trigon VA locking hole6(i.e., the corner28bopposite the base column26a) and can optionally be entirely contained within the second corner28bsuch that interface surfaces122between the VA locking hole6and compression hole92are entirely spaced from the second and third columns26b,26c.

Referring now toFIG.12A, in additional embodiments, the combi-hole90can be configured such that the trigon VA locking hole6and the compression hole92thereof retain their respective base geometries while the first axial separation distance LA1is increased relative to that of the embodiment shown inFIG.11Gby an axial distance LA3. Stated differently, the VA locking hole6and compression hole92can be moved slightly away from each other in the combi-hole90of the present embodiment. In this manner, as shown inFIG.12B, the interface edges122can effectively be limited to a few roots58and contiguous regions of the upper and lower flank portions55b,57bof the plate threads9. As used herein with respect to a hole (e.g., the VA locking hole6and the compression hole92), the terms “base geometry”, “base version”, and derivatives thereof refer to a stand-alone version of the hole6,92that is not intersected by another hole. Thus, the “base geometry” or “base version” of the VA locking hole6refers to a stand-alone version of the VA locking hole6that is not intersected by a compression hole92or another type of hole; and the “base geometry” or “base version” of the compression hole92refers to a stand-alone version of the compression hole92that is not intersected by the VA locking hole6or another type of hole. For example,FIGS.13B,14B, and15Bshow the respective base versions of the VA locking holes6of the combination holes90shown inFIGS.13A,14A, and15A. Accordingly, the features and geometries of the base versions of the VA locking holes6shown inFIGS.13B,14B, and15B(and reference numbers therein) are instructive regarding such features and geometries of the respective VA locking holes6of the combination holes90shown inFIGS.13A,14A, and15A. Thus, the reader will appreciate thatFIGS.13A and13Bshould be viewed together, as shouldFIGS.14A and14B, and alsoFIGS.15A and15B.

Referring now toFIGS.13A through13E, in further embodiments, the locking surface24acan define a thread transition zone130in which the horizontal hole profile (and the thread path about central axis22) deviates from the equilateral configuration in a manner elongating the thread path as it approaches and departs from the hole intersection zone120. In the depicted embodiment, such deviation occurs between respective column axes46bof the second and third columns26b,26c, which column axes46bare positioned and oriented where the column centerlines46of the second and third columns26b,26cwould be if these columns26b,26cwere equilateral with the base column26a. As shown inFIG.13A, the thread transition zone130can effectively move the hole intersection zone120entirely outside the radius R8of the reference circle43. Thus, it can be said that radius R8is less than a minimum distance measured from the central axis22of the VA locking hole6to the intersection boundary119with respect to the longitudinal hole direction.

As shown inFIGS.13A and13B, the second and third columns26b,26ccan be elongated linearly along the thread transition zone130so as to define columns lengths LC-2that are greater than the column length LC of the base column26a. The plate threads9on either side of the intersection axis97can define a transition length LT measured from the respective column axis46bof the second and third columns26b,26cto the intersection boundary119. As best shown inFIG.13B, which depicts an uninterrupted or “base” version6′ of the trigon VA locking hole6employed in the combi-hole90ofFIG.13A, the distance R1-2between the central axis22and the corner axis37of the second corner28bis thus greater than the distance R1between the central axis22and the corner axes37of the first and third corners28a,28c. To maintain a smooth thread path along the second corner28bof the base trigon VA locking hole6′, the second corner28bcan extend tangentially from the second side45of the second column26bto the first side44of the third column26c. Accordingly, the second corner28bof the base trigon VA locking hole6′ can define a corner radius R9-2smaller than corner radii R9of the first and third corners28a,28c. Additionally, to maintain the thread pitch P1both outside and inside the thread transition zone130, the helix angle of the plate threads9is less inside the thread transition zone130and is greater outside the thread transition zone130. Stated differently, the helix angle diminishes or “flattens out” inside the thread transition zone130.

The thread transition zone130provides the plate threads9with a smoother entry to and departure from the intersection boundary119along the thread path about the central axis22. In this manner, the thread transition zone130provides a reduction in the sharpness of the interface edges122while also maintaining the thread profiles of the plate threads9to a greater extent in the hole intersection zone120, such as with a narrower lateral gap distance G and/or with less profound relief surfaces126(or optionally no relief surfaces126) therein. Thus, even when the screw8is inserted at high angulations A1that cause the head27to enter the hole intersection zone120, the thread transition zone130can provide increased locking thread interface between the plate threads9and screw head threads29in the hole intersection zone120(and thus also overall) while also avoiding, minimizing, or at least reducing contact between abrupt and/or sharp edges of the plate threads9and screw head threads29.

In embodiments where the combi-hole90has a linear elongated transition zone130, the corner radius R9-2of the second corner28bof the base trigon VA locking hole6′ can be in a range from about 0.10 mm to about 2.5 mm and more particularly in a range from about 0.15 mm to about 0.90 mm, and more particularly in a range from about 0.175 mm to about 0.825 mm. Moreover, the distance R1-2between the central axis22and the corner axis37of the second corner28bcan be in a range from about 0.40 mm to about 6.00 mm, and more particularly in a range from about 0.75 mm to about 4.50 mm, and more particularly in a range from about 1.50 mm to about 3.75 mm. Additionally, the column length LC-2of the second and third columns26b,ccan be in a range from about 0.20 mm to about 6.00 mm, and more particularly in a range from about 0.40 mm to about 3.40 mm, and more particularly in a range from about 0.50 mm to about 2.85 mm. It should be appreciated that dimensions R8, LA1, R9, R1, and LC can be within the respective ranges described above.

According to a first non-limiting example of the present embodiment, the radius R8of the reference circle43can be about 2.050 mm, the first axial separation distance LA1can be from about 4.0 mm to about 4.8 mm, the corner radii R9of the first and third corners28a,28ccan be about 1.95 mm, the corner radius R9-2of the second corner28b(i.e., the “second corner radius”) can be about 1.10 mm, the distance R1between the central axis22and the corner axis37of the first and third corners28a,28ccan be about 0.142 mm, the distance R1-2between the central axis22and the corner axis37of the second corner28bcan be about 1.824 mm, the base column26acan have a column length LC from about 0.2 mm to about 0.35 mm, and particularly about 0.274 mm, and the second and third columns26b,26ccan each have a column length LC-2of about 1.763 mm.

According to a second non-limiting example of the present embodiment, dimensions R8, R9, LA1, LC, and R1can be substantially the same as in the first example, while the second and third columns26b,26ccan each have a column length LC-2of about 2.802 mm, the second corner radius R9-2can be about 0.200 mm, and distance R1-2can be about 2.918 mm.

In some embodiments, such as those where the trigon VA locking hole6defines an equilateral reference triangle RT and the thread transition zone130employs linearly elongated second and third columns26b,26c, the second corner radius R9-2can be in a range from about 0 mm (i.e., the first surfaces42of the second and third columns26b,26ccan intersect substantially at a single point) to substantially equivalent to corner radius R9. Additionally or alternatively, a ratio between the column length LC of the base column26ato the column lengths LC-2of the second and third columns can be in a range of about 1:1.0 to about 1:100.0, and more particularly in a range of about 1:2.0 to about 1:15, and more particularly in a range of about 1:5 to about 1:8, and more particularly about 1:6.43, by way of non-limiting examples. In further embodiments employing linear elongated transition zones130, a ratio of corner radius R9-2to radius R8can be in a range of about 0.0:1 to about 0.904:1, and more particularly in a range of about 0.400:1 to about 0.600:1, and more particularly about 0.54:1; a ratio of column length LC-2to radius R8can be in a range of about 0.0:1 to about 2.0:1, and more particularly in a range of about 0.75:1 to about 0.95:1, and more particularly about 0.86:1; and a ratio of axial separation distance LA1to radius R8can be in a range of about 0.1:1 to about 4.0:1, and more particularly in a range of about 1.0:1 to about 3.5:1, and more particularly about 2.34:1. It should be appreciated that in other embodiments the reference triangle RT need not be equilateral and need not be isosceles. For example, the columns26a-ccan be oriented such that the vertex angles AV1, AV2, AV3of the references triangle RT are each different from one another. Moreover, in some embodiments, the columns26a-ccan each have difference column lengths.

Referring now toFIG.13F, the thread transition zone130beneficially increases the straight line distances between the axial midpoint22aof the central axis22and the intersection boundary119. For example, in the present embodiment, the minimum straight line distance D1can be measured to a crest56that is not truncated by a relief surface126. Moreover, the maximum straight line distance D2can be measured to a location at which a root58of the plate threads9intersects a boundary between the compression surface96and the undercut surface36bof the compression hole92. Thus, the thread transition zone130effectively increases these minimum and maximum straight line distances D1, D2while also decreasing the gap distance G relative to the embodiments above, thereby provided increased threaded engagement between the plate threads9and the screw head threads29at angulation of the screw head27toward the compression hole92and into intersection zone120, as described below. The minimum straight line distances D1can be in a range of about 0.5 mm to about 7.0 mm, and more particularly in a range from about 1.0 mm to about 4.5 mm, and more particularly about 2.0 mm to about 3.0 mm. The maximum straight line distances D2can be in a range of about 0.5 mm to about 7.0 mm, and more particularly in a range from about 1.5 mm to about 5.0 mm, and more particularly about 2.5 mm to about 3.5 mm. A ratio of the minimum straight line distance D1to radius R8can be in a range of about 0.05:1 to about 3.0:1. A ratio of the maximum straight line distance D2to radius R8can be in a range of about 0.05:1 to about 3.0:1. The minimum gap distance G can be in a range of about 0.0 mm to about 7.0 mm, and more particularly in a range from about 0.80 mm to about 3.60 mm, and more particularly in a range from about 0.12 mm to about 2.40 mm. AlthoughFIG.13Fdepicts the intersection boundary119on only one lateral side of the combi-hole, it should be appreciated that the minimum and maximum straight line distances D1, D2can be substantially similar at the intersection boundary119on the other lateral side of combi-hole90.

Referring now toFIGS.13G and13H, angulation of the screw head27into the hole intersection zone120is shown, particularly at an angulation A1of about 15 degrees as indicated inFIG.13C. As shown inFIG.13H, even at such high angulation A1, contact between the screw head27(including the threads29thereof) and the interface edges122of the plate threads9can be significantly reduced, such as to a few interference regions99. Similarly as described above, the thread proportions of the plate threads9and screw head threads29can be configured to cause the plate threads9and/or the screw head threads29to deform favorably at such interference regions99. It should be appreciated that in further embodiments, the transition zone130can be configured so that contact between the screw head27and the interface edges122can be entirely avoided, even at high angulations.

Referring now toFIGS.14A through14E, in further embodiments, the locking surface24acan define a thread transition zone130in which transition portions132of the locking surface24aextend arcuately and convexly from the second and third columns26b,26cto the intersection boundary119. In particular, as shown inFIG.14A, the second and third columns26b,26ccan be linear and can be shortened such that the column axes46bthereof are located at the respective side44,45thereof nearest the intersection boundary119.

The second and third columns26b,26ccan define linear column lengths LC-2that are one-half the column length LC of the base column26a. Additionally, the transition portions132can extend along respective transition lengths LT, which in the present embodiment are arc lengths RC-3(seeFIG.14B), that are longer than the column lengths LC-2of the second and third columns26b,26c. However, in other embodiments, such as shown inFIGS.15A and15B, the column lengths LC-2of the second and third columns26b,26ccan be greater than the column length LC of the base column26a, and the arc lengths RC-3of the transition portions132(FIG.15B) can be shorter than the column lengths LC-2of the second and third columns26b,26c. As above, the plate threads9on either side of the intersection axis97can define a transition length LT measured from the respective column axis46bof the second and third columns26b,26cto the intersection boundary119.

As best shown inFIGS.14B and15B, which depicts the base versions6′ of the trigon VA locking holes6shown inFIGS.14A and15A, the transition portions132define a radius of curvature R11(also referred to herein individually as “transition radius” R11and collectively as “transition radii” R11), which can be constant along the second portions26-2. As in the embodiment described above, distance R1-2can be greater than distance R1. The second corner28bcan extend tangentially from the transition portion132adjacent the second column26bto the transition portion132adjacent the third column26c. The second corner28bcan define a corner radius R9-2smaller than corner radii R9of the first and third corners28a,28c. Additionally, as above, the helix angle of the plate threads9is reduced in the thread transition zone130to maintain a constant thread pitch P1both outside and inside the thread transition zone130.

It should be appreciated that, in embodiments where the combi-hole90has an arcuate, convex transition zone130, the transition radii R11can range from substantially infinite (i.e., nearly linear) to substantially 0.0 mm (i.e., a short round-off adjacent the second and third columns26b,26c). More particularly, the transition radii R11can be in a range about 0.10 mm to about 20.0 mm, and more particularly in a range from about 0.50 mm to about 6.00 mm, and more particularly in a range of about 1.75 mm to about 4.25 mm. It should be appreciated that dimensions R8, LA1, R9, R1, R1-2, LC, and LC-2can be within the respective ranges described above.

According to a first non-limiting example of the embodiments shown inFIGS.14A through15B, the radius R8of the reference circle can be about 2.050 mm, the first axial separation distance LA1can be from about 4.0 mm to about 4.8 mm, the corner radii R9of the first and third corners28a,28ccan be about 1.95 mm, distance R1can be about 0.142 mm, distance R1-2can be about 2.800 mm, the base column26acan have a column length LC from about 0.20 mm to about 0.35 mm, and more particularly about 0.274 mm, the second and third columns26b,26ccan each have a column length LC-2of about 0.550 mm, and the transition portions132can have a radius R11of about 4.943 mm.

According to a second non-limiting example of the embodiments shown inFIGS.14A through15B, dimensions R8, R9, LA1, LC, and R1can be substantially the same as in the immediately preceding example, while the second and third columns26b,26ccan each have a column length LC-2of about 1.410 mm, the radius R11of the transition portions132can be about 2.741 mm, and distance R1-2can be about 3.534 mm.

As described above, the transition radii R11can range from substantially infinite (i.e., nearly linear) to substantially 0.0 mm (i.e., a short round-off adjacent the column26b,26c). Thus, it should be appreciated that a ratio of radius R8to the transition radii R11can be in a range of about 0.0:1 to about 1:0.0. More particularly, the ratio of R8to R11can be in a range of about 1:1.0 to about 1:3.5, and more particularly in a range from about 1:2.1 to about 1:2.7. Additionally or alternatively, a ratio between the column length LC of the base column26ato the column lengths LC-2of the second and third columns can be in a range of about 1:0.1 to about 1:100, and more particularly in a range of about 1:1.0 to about 1:20.0, and more particularly in a range of about 1:2 to about 1:15, and more particularly in a range of about 1:5 to about 1:8, by way of non-limiting examples. In further embodiments employing arcuate and convex transition portions132, a ratio of axial separation distance LA1to radius R8can be in a range of about 0.1:1 to about 4.0:1, and more particularly in a range from about 0.125:1 to about 3.750:1, and more particularly in a range of about 0.155:1 to about 3.414:1. Moreover, a ratio of column length LC-2to radius R8can be in a range of about 0.1:1 to about 2.0:1, and more particularly in a range from about 0.125:1 to about 1.750:1, and more particularly in a range of about 0.134:1 to about 1.536:1.

It should be appreciated that the combi-hole90can employ a trigon VA locking hole6in which the transition zone130also transitions axially with respect the central hole axis22between the upper and lower surfaces18,20of the plate4, such that the hole6has multiple transition zone130profiles along the central hole axis22. For example, the locking surface24acan optionally include at least a first axial portion adjacent the upper plate surface18and defining a first transition zone130profile, such as any of those shown inFIGS.13A through15B, and at least a second axial portion extending axially between the first axial portion and the lower plate surface20and defining a second transition zone130profile that is different than the first horizontal hole profile.

Additional details of the combi-hole, as well as operation of a compression screw in the combination hole portion thereof, can be as more fully described in the '761 and '047 References.

Referring now toFIGS.18through20, in further embodiments, a combi-hole90′ can be effectively defined by first and second VA locking holes6that intersect one another. Such combi-holes90′ can be referred to herein as VA-VA combi-holes90′. In such embodiments, the second surface24b′ is also a locking surface. Accordingly, locking surface24acan be referred to as the first locking surface24a, and the second surface24b′ can be referred to as the second locking surface24b′. As above, the first locking surface24acan define first, second, and third columns26a,26b,26cseparated from each other by a first corner28a, a gap between the VA locking holes6(where a second corner would otherwise exist), and a third corner28c, respectively. The second locking surface24b′ can define fourth, fifth, and sixth columns26d,26c,26fseparated from each other by a fourth corner28d, the gap (where a fifth corner would otherwise exist), and a sixth corner28f, respectively. The threads9of the combi-hole90′ extend along one or more thread paths (i.e., single-lead, double-lead, etc.) that preferably traverse the locking surfaces24a,24b′ in uninterrupted fashion between the upper and lower surfaces18,20of the bone plate4. The VA-VA combi-holes90′ can be defined by polygonal-shaped VA locking holes6, such as the trigon-shaped VA locking holes6depicted, although any of the polygonal-shaped VA locking holes6described above can be incorporated into a VA-VA combi-hole90′.

The VA-VA combi-holes90′ of the present embodiments can employ thread transition zones130similar to those described above with reference toFIGS.13A-15B. For example, as shown inFIG.18, the VA-VA combi-hole90′ can define a linear elongated transition zone130on each longitudinal side of the intersection boundary119. In such embodiments, the intersection boundary119can define an interface between the second and sixth columns26b,fand another interface between the third and fifth columns26c,e. In other embodiments, as shown inFIGS.19and20, the combi-holes90′ can employ arcuate, convex thread transition zones130and transition portions132, similar to those described above. For example, the VA-VA combi-hole90′ ofFIG.19can employ a thread transition zone130in which the first and second locking surfaces24a,24b′ define elongated arcuate, convex transition portions132on each longitudinal side of the intersection boundary119, each similar to the transition portions132described above with reference toFIGS.14A through14E. Moreover, the VA-VA combi-hole90′ ofFIG.20can employ a thread transition zone130in which the first and second locking surfaces24a,24b′ define elongated columns26b,c,e,fand arcuate, convex transition portions132on each longitudinal side of the intersection boundary119, similar to the transition zone130described above with reference toFIGS.15A and15B. It should be appreciated that, in other embodiments, the VA-VA combi-hole90′ can be devoid of a thread transition region (such as the thread transition regions130described above with reference toFIGS.13A-15B).

It should further be appreciated that any of the combi-holes described above can be modified such that the VA locking hole(s)6thereof employs a polygonal horizontal hole profile according to any of the polygonal hole shapes described herein.

With reference toFIGS.21A through29G, additional examples of bone plates will be described that include various trigon locking hole geometries, such as stand-alone locking holes and combi-holes having a locking hole intersected by a compression hole.

FIGS.21A through21Gshow an example bone plate, particularly a bone plate for treating a medial distal portion of a tibia, the bone plate having a “low bend” geometry and having locking holes, including stand-alone locking holes and combi-holes that employ trigon VA locking hole geometries, wherein at least some and up to all of the locking holes are configured for use with standard-type locking screws having shaft major diameters of about 3.5 mm. According to one naming convention, the bone plate of the present example can be categorized as follows: LCP Medial Distal Tibial Plate 3.5, Low Bend.

FIGS.22A through22Gshow an example bone plate, particularly a bone plate for treating an olecranon, the bone plate having locking holes, including stand-alone locking holes and combi-holes that employ trigon VA locking hole geometries, wherein at least some and up to all of the locking holes are configured for use with both standard-type locking screws and VA locking screws having shaft major diameters from about 2.7 mm to about 3.5 mm. According to one naming convention, the bone plate of the present example can be categorized as follows: VA-LCP Olecranon Plate 2.7/3.5.

FIGS.23A through23Gshow an example bone plate, particularly a bone plate for treating a distal radius, the bone plate having locking holes, including stand-alone locking holes and combi-holes that employ trigon VA locking hole geometries, wherein at least some and up to all of the locking holes are configured for use with both standard-type locking screws and VA locking screws having shaft major diameters of about 2.4 mm. According to one naming convention, the bone plate of the present example can be categorized as follows: VA-LCP Two-Column Distal Radius Plate 2.4.

FIGS.24A through24Gshow an example show an example bone plate, particularly a bone plate for treating a lateral distal fibula, the bone plate having locking holes, including stand-alone locking holes and combi-holes that employ trigon VA locking hole geometries, wherein at least some and up to all of the locking holes are configured for use with both standard-type locking screws and VA locking screws having shaft major diameters of about 2.7 mm. According to one naming convention, the bone plate of the present example can be categorized as follows: VA-LCP Lateral Distal Fibula Plate 2.7.

FIGS.25A through25Gshow an example show an example bone plate, particularly a bone plate for treating a condyle, the bone plate having locking holes, including combi-holes that employ trigon VA locking hole geometries and also stand-alone locking holes having different geometries, wherein at least some and up to all of the locking holes are configured for use with both standard-type locking screws and VA locking screws having shaft major diameters from about 4.5 mm to about 5.0 mm. According to one naming convention, the bone plate of the present example can be categorized as follows: VA-LCP Condylar Plate 4.5/5.0.

FIGS.26A through26Gshow an example show an example bone plate, particularly a bone plate for treating a proximal tibia, the bone plate having a “small bend” geometry having locking holes, including stand-alone locking holes and combi-holes that employ trigon VA locking hole geometries, wherein at least some and up to all of the locking holes are configured for use with both standard-type locking screws and VA locking screws having shaft major diameters of about 3.5 mm. According to one naming convention, the bone plate of the present example can be categorized as follows: VA-LCP Proximal Tibial Plate 3.5, Small Bend.

FIGS.27A through27Gshow an example show an example bone plate, particularly a bone plate for treating a proximal humerus, the bone plate having locking holes, including stand-alone locking holes and combi-holes that employ trigon locking hole geometries, wherein at least some and up to all of the locking holes are configured for use with standard-type locking screws. According to one naming convention, the bone plate of the present example can be categorized as follows: LCP Proximal Humerus Plate (Philos).

FIGS.28A through28Gshow an example show an example bone plate, particularly a straight bone plate having combi-holes that employ trigon locking hole geometries, wherein the locking holes are configured for use with standard-type locking screws having shaft major diameters of about 3.5 mm. According to one naming convention, the bone plate of the present example can be categorized as follows: LCP Plate 3.5, straight

FIGS.29A through29Gshow an example show an example bone plate, particularly a straight bone plate having stand-alone locking holes that employ trigon locking hole geometries. According to one naming convention, the bone plate of the present example can be categorized as follows: ⅓ Tubular Locking.

Although the disclosure has 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 disclosure is not intended to be limited to the particular embodiments described in the specification. As one of ordinary skill in the art will readily appreciate from that 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 disclosure.