U.S. patent application number 13/524506 was filed with the patent office on 2012-12-20 for variable angle locking implant.
This patent application is currently assigned to SMITH & NEPHEW, INC.. Invention is credited to Charles R. Baker, Darin S. Gerlach, Ryan Stevenson.
Application Number | 20120323284 13/524506 |
Document ID | / |
Family ID | 47354289 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120323284 |
Kind Code |
A1 |
Baker; Charles R. ; et
al. |
December 20, 2012 |
VARIABLE ANGLE LOCKING IMPLANT
Abstract
A variable angle locking implant includes a bone plate having a
lower surface, an upper surface, and at least one opening extending
from the lower surface to the upper surface along an axis. The
opening has a plurality of fins oriented along a plane. The axis is
non-perpendicular to a tangent of a projection of the lower surface
across the opening, the tangent defined at the intersection between
the axis and the projected lower surface, and/or the plane is
non-parallel to the tangent. The implant includes at least one
fastener, and the plurality of fins are deflectable relative to a
head portion of the fastener such that the fastener can be inserted
and retained at any one of a plurality of angles.
Inventors: |
Baker; Charles R.;
(Arlington, TN) ; Stevenson; Ryan; (Southaven,
MS) ; Gerlach; Darin S.; (Germantown, TN) |
Assignee: |
SMITH & NEPHEW, INC.
Memphis
TN
|
Family ID: |
47354289 |
Appl. No.: |
13/524506 |
Filed: |
June 15, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61497180 |
Jun 15, 2011 |
|
|
|
Current U.S.
Class: |
606/289 ;
606/280 |
Current CPC
Class: |
A61B 17/8052
20130101 |
Class at
Publication: |
606/289 ;
606/280 |
International
Class: |
A61B 17/80 20060101
A61B017/80 |
Claims
1. A variable angle locking implant comprising: a bone plate having
a lower surface; an upper surface; and at least one opening
extending from the lower surface to the upper surface along an
axis, the opening having an inner surface with a plurality of fins
oriented along a plane, wherein the axis is non-perpendicular to a
tangent of a projection of the lower surface across the opening,
the tangent defined at the intersection between the axis and the
projected lower surface, and/or the plane is non-parallel to the
tangent.
2. The implant of claim 1 wherein the lower surface comprises a
bone conforming arcuate surface.
3. The implant of claim 2 wherein the lower surface is adapted to
contact a distal femur, a proximal femur, a distal tibia, a
proximal tibia, a proximal humerus, a distal humerus, a clavicle, a
fibula, an ulna, a radius, a distal radius, a rib, pelvis, a
vertebra, bones of the foot, or bones of the hand.
4. The implant of claim 2 wherein the fins are positioned within
the opening.
5. The implant of claim 1 wherein the axis is perpendicular to the
tangent and the plane is non-parallel to the tangent.
6. The implant of claim 1 wherein the axis is non-perpendicular to
the tangent and the plane is non-parallel to the tangent.
7. The implant of claim 1 wherein the axis is non-perpendicular to
the tangent and the plane is perpendicular to the axis.
8. The implant of claim 1 wherein the fins are integrally connected
to, and protruding from, the inner surface.
9. The implant of claim 8 wherein the opening has a radius between
the inner surface and a top surface of the fins, and each fin
tapers in thickness from the inner surface towards its terminal
end.
10. The implant of claim 8 wherein the opening is further defined
by a jagged circumference formed by protruding fins at the lower
surface.
11. The implant of claim 8 wherein the protruding fins form a
concave portion of the inner surface.
12. The implant of claim 8 wherein the protruding fins have bases
that meet the inner surface along the plane.
13. The implant of claim 1 wherein the fins have a tapered shape or
a straight shape.
14. The implant of claim 1 wherein the fins are provided in more
than one layer.
15. The implant of claim 1 wherein the fins are
trapezoidally-shaped, rounded, oval, rectangular, curved, rhomboid,
diamond-shaped, or triangular.
16. The implant of claim 1 wherein the edges of the fins taper
inwardly, outwardly, or are about parallel with one another.
17. The implant of claim 1 comprising at least 3, but no more than
10, fins integrally connected to, and protruding from, the inner
surface.
18. The implant of claim 1 wherein the fins are provided as a
series of concavely indented, inwardly protruding fins that are
adapted to secure a threaded head of a fastener in place at varying
angles.
19. The implant of claim 1 wherein the bone plate further comprises
one or more of the following openings: a threaded opening; a
non-threaded opening; an opening adapted to receive locking or
non-locking fasteners; an opening with fins; a provisional fixation
opening; a combination slot; or any combination thereof.
20. The implant of claim 1 further comprising at least one
fastener, the fastener being at least partially threaded and having
a head portion and a shaft portion, wherein the opening is adapted
to receive the fastener without being tapped by the fastener,
wherein the plurality of fins are deflectable relative to the head
portion of the fastener when the fastener is inserted into the
opening such that the fastener can be inserted and retained at any
one of a plurality of angles relative to the opening.
21. The implant of claim 20 wherein the fins are deflectable so
that the fins are interposed between the threads of the
fastener.
22. The implant of claim 1 wherein the inner surface comprises
threads located above or below the fins.
23. A method for securing a bone plate to a bone, comprising:
placing a lower surface of the bone plate against the bone;
inserting a fastener into an opening in the bone plate, the opening
having an axis that is non-perpendicular to a tangent of a
projection of the lower surface across the opening, the tangent
defined at the intersection between the axis and the projected
lower surface; selecting a trajectory of the fastener into the
bone, the trajectory being up to about 15 degrees off the hole
axis; and inserting the fastener into the bone.
24. The method of claim 23 wherein either a locking screw or a
non-locking screw is inserted in the opening.
25. The method of claim 23 wherein the fastener is removed and
re-inserted into the opening of the bone plate at any one of a
plurality of angles.
26. The method of claim 23 wherein inserting the fastener into the
bone comprises drawing a bone fragment into alignment with an
intact bone segment.
27. The implant of claim 1 wherein at least one opening has an axis
that is non-perpendicular to the tangent and at least one opening
has an axis that is perpendicular to the tangent.
28. The implant of claim 1 wherein at least one opening has an axis
that is non-perpendicular to the tangent and at least one opening
is threaded.
29. The implant of claim 1 wherein at least one opening has an axis
that is non-perpendicular to the tangent and at least one opening
is non-threaded.
30. The implant of claim 1 wherein at least one opening has an axis
that is perpendicular to the tangent and at least one opening is
threaded.
31. The implant of claim 1 wherein at least one opening has an axis
that is perpendicular to the tangent and at least one opening is
non-threaded.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the full benefit of
U.S. Provisional Application Ser. No. 61/497,180 filed Jun. 15,
2011, and titled "Variable Angle Locking Implant," the entire
contents of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] This invention relates to a variable angle locking
implant.
BACKGROUND
[0003] Variable angle locking implants for repairing bone fractures
have been described, for example, in U.S. patent application Ser.
No. 12/484,527, filed Jun. 15, 2009, published as U.S. Publication
No. 2009/0312803, hereby incorporated herein by reference in its
entirety. In particular, U.S. Publication No. 2009/0312803
describes an implant having fastener receiving holes with fins that
permit a fastener to be positioned off-axis within the hole.
[0004] Implants such as bone plates have been provided with
threaded holes (that may receive either locking screws or
non-locking screws), non-threaded holes (for non-locking screws),
partially threaded slots to allow either non-locking or locking
screws to be used together, and combinations of the above.
SUMMARY
[0005] The variable angle locking implant provides a stable
connection between a bone and a bone plate using a fastener that
permits different angles to be obtained between the bone plate and
the fastener, while the fastener also locks into the bone plate.
This allows the surgeon to reach denser areas of bone or capture
random bone fragments that are in irregular positions, for example,
in cases of severe fractures with highly fragmented bones. The
fastener and plate system advantageously allows the surgeon to
choose the angle at which the screw is inserted through, and
rigidly affixed in, an opening of the plate.
[0006] The variable angle locking implant allows a surgeon to
direct the fastener toward bone fragments that are not necessarily
located along the axis of the opening in the plate. It also
provides flexibility in the placement of the plate in relation to
the bone fracture. Allowing surgeons to choose the angle at which
the fastener is inserted into the plate leads to better tailoring
of the system to the specific nature of the bone fracture to be
treated, and allows surgeons to adjust their strategy as necessary
after the surgical site has been accessed, but prior to insertion
of the fastener into bone material.
[0007] According to one aspect, a variable angle locking implant
includes a bone plate having a lower surface, an upper surface, and
at least one opening extending from the lower surface to the upper
surface along an axis. The opening has an inner surface with a
plurality of fins oriented along a plane. The axis is
non-perpendicular to a tangent of a projection of the lower surface
across the opening, the tangent defined at the intersection between
the axis and the projected lower surface, and/or the plane is
non-parallel to the tangent.
[0008] Implementations of this aspect may include one or more of
the following features.
[0009] For example, the lower surface includes a bone conforming
arcuate surface. The lower surface is adapted to contact a distal
femur, a proximal femur, a distal tibia, a proximal tibia, a
proximal humerus, a distal humerus, a clavicle, a fibula, an ulna,
a radius, a distal radius, a rib, pelvis, a vertebra, bones of the
foot, or bones of the hand, shaft fractures on long bones, or any
of the aforementioned adjacent bones in the case of a joint fusion
plate.
[0010] The fins are positioned within the opening. The axis is
perpendicular to the tangent and the plane is non-parallel to the
tangent. Alternatively, the axis is non-perpendicular to the
tangent and the plane is non-parallel to the tangent, for example,
the plane is perpendicular to the axis.
[0011] The fins are integrally connected to, and protruding from,
the inner surface. The opening has a radius between the inner
surface and the top of the fins, and each fin tapers in thickness
from the inner surface towards its terminal end. The opening has a
jagged circumference formed by protruding fins at the lower
surface. The protruding fins form a concave portion of the inner
surface. The protruding fins have bases that meet the inner surface
along the plane. The fins have a tapered shape or a straight shape.
The fins are provided in more than one layer. The fins are
trapezoidally-shaped, rounded, oval, rectangular, curved, rhomboid,
diamond-shaped, or triangular. The edges of the fins taper
inwardly, outwardly, or are about parallel with one another. There
are at least 3, but no more than 10, fins integrally connected to,
and protruding from, the inner surface. The fins are provided as a
series of concavely indented, inwardly protruding fins that are
adapted to secure a threaded head of a fastener in place at varying
angles.
[0012] The bone plate includes one or more of the following
openings: a threaded opening; a non-threaded opening; an opening
adapted to receive locking or non-locking fasteners; an opening
with fins; a provisional fixation opening; a combination slot; or
any combination thereof.
[0013] The implant includes at least one fastener. The fastener is
at least partially threaded and has a head portion and a shaft
portion. The opening is adapted to receive the fastener without
being tapped by the fastener. The plurality of fins are deflectable
relative to the head portion of the fastener when the fastener is
inserted into the opening such that the fastener can be inserted
and retained at any one of a plurality of angles relative to the
opening. The fins are deflectable so that the fins are interposed
between the threads of the fastener. The inner surface includes
threads located above or below the fins.
[0014] According to another aspect, a method for securing a bone
plate to a bone includes placing a lower surface of the bone plate
against the bone; inserting a fastener into an opening in the bone
plate, the opening having an axis that is non-perpendicular to a
tangent of a projection of the lower surface across the opening,
the tangent defined at the intersection between the axis and the
projected lower surface,; selecting a trajectory of the fastener
into the bone, the trajectory being up to about 15 degrees off the
hole axis; and inserting the fastener into the bone.
[0015] Implementations of this aspect may include one or more of
the following features.
[0016] For example, either a locking screw or a non-locking screw
is inserted in the opening. The fastener is removed and re-inserted
into the opening of the bone plate at any one of a plurality of
angles. Inserting the fastener into the bone includes drawing a
bone fragment into alignment with an intact bone segment.
[0017] The details of one or more implementations of the invention
are set forth in the accompanying drawings and the description
below. Other features, objects, and advantages of the invention
will be apparent from the description and drawings, and from the
claims.
DESCRIPTION OF DRAWINGS
[0018] FIG. 1 is an illustration of a variable angle locking
implant positioned on a bone.
[0019] FIG. 2 is a cross-sectional view of the variable angle
locking implant taken along line 2-2 of FIG. 1.
[0020] FIG. 3 is a perspective view of a bone plate and fastener of
the variable angle locking implant.
[0021] FIG. 4 is a perspective view of a bone plate of the variable
angle locking implant having a finned opening.
[0022] FIGS. 5A-5E are cross-sectional views of various
implementations of the finned opening.
DETAILED DESCRIPTION
[0023] Referring to FIGS. 1 and 2, a variable angle locking implant
2 for repairing fractures in bone 4 includes a bone plate 40 and
one or more fasteners 90. A fastener 90 is shown engaged in a
finned opening 50 that extends between an upper surface 44 and a
lower, bone contacting surface 42 of the bone plate 40. The
fastener 90 can be positioned in the opening 50 and fixed in the
plate 40 at various insertion angles to capture "renegade" or
random bone fragments that have split from the bone during fracture
and secure the bone fragments to the plate 40.
[0024] The fastener 90 shows a new trajectory achieved by
increasing the range of angles as compared to the screw 90a. For
example, the central axis 96 of fastener 90 has an approximate 15
degree offset from the central axis 52 and approximately 30 degree
offset from perpendicular to the lower surface 42 of the bone plate
40. The alternative placement of a screw 90a in a hole having an
axis 52 perpendicular to the lower surface 42 of the plate 40 and a
plane 59 that is parallel to the bottom lower surface 42
illustrates approximately a 15 degree offset from the central axis
52 and a corresponding approximately 15 degree offset from
perpendicular to the lower surface 42 of the bone plate 40, thus
illustrating the greater range of the insertion angle of the
fastener 90.
[0025] The locking implant 2 also includes a provisional pin
opening 102 as well as a combination slot 104.
[0026] Referring also to FIGS. 3 and 4, the plate 40 has an inner
surface 54 that defines the opening 50 and a series of concavely
indented, inwardly protruding fins 56 that extend toward a central
axis 52 of the opening 50. Each fin 56 has a base 58 and the bases
58 form concave portions 60. The bases 58 of the fins 56 all meet,
for example, in substantially the same plane 59a-59d (FIGS. 5A-5D)
and then angle downwardly and inwardly at a similar angle or slope.
As discussed further below, the central axis 52 can be oriented
non-perpendicular to the lower surface 42 and/or the planes 59a-59d
can be oriented non-parallel to the lower surface 42 to increase
the range of possible insertion angles.
[0027] The concave portions 60 are smooth and non-threaded, and as
illustrated, the entire inner surface 54 of the finned opening 50
can be devoid of threads. The lack of threads helps ease the
manufacturing of the plate 40, and allows the plate 40 to be
manufactured as thinly as desired. The bases 58 can extend from the
inner surface 54 at or near an upper circumference 62 of the inner
surface, at a middle region of the inner surface, or at or near a
lower circumference of the inner surface. With the fins 56 located
adjacent a lower circumference at the lower, bone contacting
surface 42 of plate 40, the lower circumference appears jagged due
to the presence of the fins, while the upper circumference 62 is
smooth.
[0028] As the fins 56 extend toward central axis 52, they taper to
form tapered sides 64. The fins 56 end at rounded tips 66, although
tips 66 can be pointed, square, rectangular, or any other
appropriate configuration. For example, as described in U.S. Patent
Application Publication No. 2009/0312803, which is incorporated
herein by reference in its entirety, the fins 56 can have straight
edges or sides and straight ends such that the fins are partially
rectangular-shaped with slit-shaped openings between the fins.
Alternatively, the fins can be more triangular in shape having
sides that taper inwardly and end edges that are flat and small.
Other example fin shapes include trapezoidal, square, round,
circular, triangular (with a pointed tip).
[0029] The dimensions of fins 56 are typically dependent at least
in part upon the pitch and threads of the fastener 90. For example,
a larger plate 40 for use with a larger fastener 90 (for example,
for use on a femur bone) will likely be thicker and will have
larger and thicker fins 56 than a smaller plate 40 (for example,
for use on a smaller bone). In specific implementations, the fins
56 are particularly thin so that they can be moved up or down and
deformed under pressure. In some implementations, the fins 56 may
be pressed toward the edges of the finned opening 50. A
non-limiting exemplary range of thicknesses for the fins 56 is from
about 0.15 mm to about 5 mm, although larger and smaller sizes are
possible. The fins 56 are intended to fit between threads 98 on the
thread form of fastener 90, as shown in FIG. 3.
[0030] Providing a non-threaded inner surface 54 also allows the
fastener 90 to be inserted into the finned opening 50 at any
desired insertion angle, that is the angle defined between a
longitudinal axis 96 (FIG. 2) of the fastener 90 and the central
axis 52 (FIG. 4) of the finned opening 50. The central axis 52 and
the longitudinal axis 96 can be co-linear so that the insertion
angle is zero, or the central axis 52 and the longitudinal axis 96
(FIG. 1) can be non-co-linear with an insertion angle of up to
about +/-15 degrees. Varying the insertion angle is possible
because there are not any threads in the finned opening 50 to
interfere with the desired insertion angle. The fins 56 are
intended to slightly bend or deform in order to secure the fastener
90 in place in the finned opening 50. The fins 56 engage the
threads 98 or other surface of the fastener 90.
[0031] The fastener 90 has a head 94 and a shaft 92. The shaft 92
may be threaded or non-threaded. The head 94 of the fastener 90 has
at least one set of threads 98 and a bore 18 for receiving a driver
in order to drive the fastener 90 through the plate 40 and into
bone. The threads 98 are typically any standard-type thread.
[0032] Referring to FIGS. 5A and 5B, the central axis 52a, 52b of
the opening 50 can be oriented non-perpendicular to the lower
surface 42 of the plate 40, for example, at an angle, .theta., in
the range between 0 and 90 degrees. In FIG. 5A, two rows of fins 56
are illustrated that each lie in a plane 59a that is parallel to
the lower surface 42 of the plate 40. In FIG. 5B, the fins 56 lie
in a plane 59b that is oriented non-parallel to the lower surface
42 of the plate 40, for example, the plane 59b is perpendicular or
nearly perpendicular to the axis 52b. In FIG. 5C, the fins 56 are
illustrated lying in a plane 59c that is oriented non-parallel to
the lower surface 42 of the plate 40 and the plane 59c is
non-perpendicular to the axis 52c. The fins 56 of FIGS. 5B and 5C
are positioned within the opening 50, that is, between the upper
surface 44 and lower surface 42 of the plate 40.
[0033] The non-perpendicular orientation of the central axis 52a,
52b, 52d and/or the non-parallel orientation of the plane 59b-d
increases the useful range of possible insertion angles as compared
to a bone plate 40 having the central axis 52 perpendicular to the
lower surface 42 and the plane 59 parallel to the lower surface 42.
For example, referring to FIG. 5B, assuming .theta. is 15 degrees,
a fastener 90 could be inserted with the fastener axis 96 aligned
with axis 52b, and thus 15 degrees off from perpendicular to the
lower surface 42, or the fastener axis 96 could be tilted up to,
for example, +/-15 degrees, such that the fastener axis 96 is
perpendicular to the lower surface 42 or up to 30 degrees off from
perpendicular to reach bone fragments. Increasing the range of
angles allows the surgeon to target new fastener trajectories in
the bone as shown in FIG. 2.
[0034] The screw 90 (FIG. 2) shows a new trajectory achieved by
increasing the range of angles as compared to the screw 90a. The
fastener 90 is shown positioned in the hole of FIG. 5B and having a
15 degree offset from the central axis 52 and 30 degree offset from
perpendicular to the lower surface 42 of the bone plate 40. The
alternative placement of a screw 90a in a hole having an axis 52
perpendicular to the lower surface 42 of the plate 40 and a plane
59 that is parallel to the lower surface 42 illustrates a 15 degree
offset from the central axis 52 and only a corresponding 15 degree
offset from perpendicular to the lower surface 42 of the bone plate
40, thus illustrating the greater range of the insertion angle of
the fastener 90. Angling the screw greater than 15 degrees from the
central axis 52 of an opening having an axis 52 perpendicular to
the lower surface 42 of the plate 40 and a plane 59 that is
parallel to the lower surface 42 produces inconsistent failure
loads. Therefore, to achieve a screw trajectory greater than 15
degrees from the lower surface 42 of the plate 40 while maintaining
the ability to capture and secure bone fragments, the angle of the
central axis 52 is offset from perpendicular to the lower surface
42 and the screw axis 96 tilted to reach a maximum of 30 degrees
offset.
[0035] Referring to FIG. 5D, the range of insertion angles can also
be increased by orienting the axis 52d of the opening 50
perpendicular to the lower surface 42 of the plate 40, while the
fins 56 lie in a plane 59d that is non-parallel to the lower
surface, for example, at an angle, .alpha., in the range between 0
and 90 degrees.
[0036] The finned opening 50 can include about five to eight fins
56, as illustrated, two or three fins 56, or ten or twenty or more
fins 56, depending upon the plate 40 for which the finned opening
50 is intended for use. The finned holes can optionally include
threads 112 (FIG. 5B) formed above or below the fins in the inner
surface of the hole. The region of the opening above the fins can
taper inwardly from the upper surface of the plate, for example, at
an angle of about 5 to 15 degrees, and the region of the opening
below the fins can taper outwardly toward the lower surface of the
plate, for example, at an angle of about 40 to 50 degrees. The
finned opening 50 can optionally be a slot hole or combination hole
with half or more of the length of the opening can be finned with
the remainder of the opening being non-threaded for sliding
compression.
[0037] The primary purpose of fins 56 is to grasp one or more
threads 98 of the fastener 90 in order to secure the fastener 90 in
place in the bone plate 40 at any desired insertion angle.
Fasteners 90 received in different finned openings 50 can be
inserted at the same or different insertion angles. As a fastener
90 is inserted, its threads 98 start to engage the fins 56, as
shown in FIG. 3. As discussed above, the fins 56 can be very thin
so that as the threads 98 start to grab the fins 56, the fins 56
can move up or down as appropriate to engage the threads 98 and
secure the fastener 90 in the finned opening 50. The threads 98
engage the fins 56 so that the fins 56 fit between the threads 98.
The movement of fins 56 can be a permanent deformation, so that the
fins 56 cannot flex back and allow the fastener 90 to work its way
out.
[0038] The finned openings 50 can be provided on all types of bone
plates 40 and can be combined with other types of openings. As
illustrated in FIG. 1, there can be finned openings 50, a threaded
opening 30, and a provisional pin opening 102. Other options are
holes that can be used with either a threaded or non-threaded
fastener, as well as combination slots 104. For example, a slot
having fins mounted on either or both ends of the slot for static
locking and no threads or fins in the middle portion of the slot
for dynamic locking These various types of openings may be used on
any type of bone plate, in any combination and in any size. The
inclusion of a plurality of finned openings 50 in the bone plate 40
can help achieve better fixation of a fractured bone, for example,
where numerous fragments have shattered in various directions,
because the fasteners 90 can be inserted at various angles to
capture "renegade" or random bone fragments that have split from
the bone during fracture, but still secure the bone fragments to
the plate 40.
[0039] The threads 98 on fastener 90 can be any type of standard or
non-standard thread. For example, the threads 98 can be a
continuous ridge or a non-continuous ridge. The threads 98 can form
a portion of a revolution, one complete revolution, multiple
revolutions, a single lead, or multiple leads, or any other threads
known in the art. Additionally or alternatively, the head 94 of
fastener 90 can include any other surface that will engage with and
seat within the fins 56 of the finned opening 50. For example, the
head 94 can have a series of dimples, ridges, bumps, textured
areas, or any other surface that can secure fastener 90.
[0040] The fastener 90 may be any typical fastener, made out of any
appropriate material. The fastener 90 typically has a bore 18 for
receiving a driver in order to drive the fastener 90 through the
plate 40 and into bone. The bore 18 may be any size and shape, for
example, it may have a hexagonal configuration to receive a
corresponding hexagonal driver, a Phillips screw head, a flat-head,
a star configuration, Torx, or any other appropriate configuration
that can cooperate with a driver to drive the fastener 90 into the
plate 40.
[0041] The shaft 92 may be fully threaded, partially threaded, or a
helical blade, and/or may include one or more tacks, deployable
talons, expandable elements, or any feature that allows shaft 92 to
engage bone. It is also possible that shaft 92 is not threaded, so
that fastener 90 takes the form of a peg or a pin. This alternative
implementation may be preferred in certain procedures where, for
instance, the main goal is to prevent tilting of a bone segment or
in procedures where there is no concern of fastener 90 pulling out
from the bone and hence no need for shaft 92 to be threaded or
otherwise configured to engage bone. The end of shaft 92 may be a
self-tapping or self-drilling tip.
[0042] The bone plate 40 may be adapted to contact one or more of a
distal femur, a proximal femur, a distal tibia, a proximal tibia, a
proximal humerus, a distal humerus, a clavicle, a fibula, an ulna,
a radius, a distal radius, a rib, pelvis, a vertebra, bones of the
foot, or bones of the hand, shaft fractures on long bones, or any
of the aforementioned adjacent bones in the case of a joint fusion
plate. The bone plate 40 may be curved, contoured, straight, or
flat. The lower, bone contacting surface 42 can have an arcuate
shape that conforms to the bone. For example, referring to FIG. 5E,
the bone plate 40 is shown with a bone contacting surface 42 having
an arcuate or curved shape. In the implementation shown, the
central axis 52 of the opening 50 can be oriented non-perpendicular
to a tangent line or tangent plane T-T of the projected arcuate
bone contacting surface 42 that intersects the central axis 52 at a
point P along the projected bone contacting surface 42, for
example, at an angle, .theta., in the range of between 0 and 90
degrees. In FIG. 5E, a row of fins 56 is illustrated that each lie
in a plane 59e that is oriented non-parallel to the tangent line or
plane T-T. The fins 56 can alternatively be located at the lower
surface 42 and also have an arcuate shape that conforms to the
bone. The plate can be a periarticular plate or a straight plate.
The plate may have a head portion that is contoured to conform to a
particular bone surface, such as a metaphysis or diaphysis, that
flares out from the shaft portion, that forms an L-shape, T-shape,
Y-shape, with the shaft portion, or that forms any other
appropriate shape to fit the bone to be treated.
[0043] The bone plate 40 can be made from metal, a resorbable or
non-resorbable plastic, ceramic, or composite materials. Suitable
materials may include, for example, titanium, stainless steel,
cobalt chrome, polyetheretherketone (PEEK), polyethylene, ultra
high molecular weight polyethylene (UHMWPE), resorbable polylactic
acid (PLA), polyglycolic acid (PGA), combinations or alloys of such
materials or any other appropriate material that has sufficient
strength to be secured to and hold bone, while also having
sufficient biocompatibility to be implanted into a body.
[0044] Turning now to the methods of implantation, the surgeon
accesses the surgical site of interest, which can be an internal
site at which a bone fracture is located that requires
stabilization to ensure proper healing. The fracture may be reduced
with conventional forceps and guides (which are known to those in
the art), and a bone plate 40 of appropriate size and shape is
placed over the fracture site. In some instances, the bone plate 40
may be temporarily secured to the bone 4 using provisional fixation
pins. The provisional fixation pins may be used through either the
provisional pin openings 102, or any other opening in the plate 40.
Provisional fixation provides for temporarily securing the bone
plate 40 to the bone 4 before placing fixation screws through the
bone plate 40, so that one can be certain the bone plate 40 is
properly positioned before placing bone screws for permanent
fixation of the bone plate 40 to the bone 4. Moreover, with
provisional fixation, x-rays can be taken of the bone
plate/construct without excess instruments in the field of
view.
[0045] Once the plate 40 is secured at a desired location in
relation to the fracture (typically using one or more provisional
fixation pins, although any other appropriate method may be used),
the surgeon then identifies an insertion angle at which the
fastener 90 is to be inserted through a selected opening 50 and
driven into bone material 4. If the bone plate 40 includes more
than one opening 50, the surgeon also selects the specific opening
50 to be used. After selecting the desired insertion angle and the
opening 50, the surgeon inserts the shaft 92 of the fastener 90
through the opening 50 until the tip contacts bone material 4. In
some cases, a hole may need to be drilled or tapped into the bone 4
along the insertion angle to facilitate the initial tapping or
insertion of the fastener 90. The surgeon then uses an appropriate
driving tool in the bore 18 of the head 94 to manipulate the
fastener 90 into place.
[0046] Because the fastener 90 can be inserted at angles up to
about 60 degrees from perpendicular to the lower surface of the
plate, the fastener 90 can be used to grab and/or secure bone
fragments that are out of line with the traditional angle at which
a locking screw would normally be inserted. The surgeon may need to
toggle or maneuver the fastener 90 in order to secure and draw in
displaced bone fragments.
[0047] Once the bone fragment is secured, the fastener 90 is ready
to be secured to the plate 40. As the fastener 90 is driven further
into bone 4, it is also drawn further into the plate 40. As the
threads 98 of the fastener head 94 begin to contact the fins 56,
the fins 56 engage within the threads 98 to hold the fastener 90 in
place at the desired insertion angle. The action of engagement
between the fins 56 and the threads 98 rigidly affixes the fastener
90 to the bone plate 40 at the desired insertion angle.
[0048] The surgeon may then use traditional locking and/or
non-locking screws in other openings on the plate 40. This can help
further secure the bone plate 40 to the bone fracture if
needed.
[0049] Once all the fasteners and/or screws are placed, the surgeon
may place covers over the unused openings, particularly if there
are any unused openings that cross the fracture, to strengthen the
plate 40. Additionally or alternatively, the surgeon may use bone
graft material, bone cement, bone void filler, and any other
material to help heal the bone.
[0050] In practice, a first screw is initially inserted through a
bone plate 40 and into a bone 4 on one side of a fracture and then
a second screw is inserted through the bone plate 40 on the
opposite side of the fracture. In particular, after the first screw
is in place, an axial compression screw is inserted through a hole
in the bone plate 40 on a side of the fracture opposite the side of
the first screw. The compression screw may be inserted through the
hole and into the bone 4 such that as the compression screw is
fully inserted, the bone plate 40 is drawn over to a desired
position. By moving the bone plate 40, the tissue is pulled
together to reduce the fracture. Once the compression screw has
been used to move the bone plate 40 into the desired position, the
compression screw may be removed from the bone 4 and bone plate 40
and a locking screw may be inserted through the opening 50 in the
bone plate 40 and in the bone 4 in the space formerly occupied by
the compression screw. The locking screw can then be tightened to
lock the plate 40 into position. The replacement of the compression
screw with the locking screw is not required, but a locking screw
may provide more stability and rigid fixation than leaving the
compression screw in place. In some modes of operation, a locking
screw is placed directly in a locking hole without first inserting
a compression screw in the hole.
[0051] A number of implementations of the invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. Accordingly, other implementations are
within the scope of the following claims. For example, locking
screws, non-locking screws, or other fasteners may be used. One or
more openings having a non-perpendicular orientation of the central
axis 52 and/or the non-parallel orientation of the plane 59 can be
employed to receive a fastener in implants other than plates, such
as in an acetabular cup or glenoid base component, to increase the
useful range of possible insertion angles of the fastener.
According to another implementation, the head of the screw 94 can
include the fins 56 and the opening 50 can be threaded, with the
opening having a non-perpendicular orientation of its central axis
52 and/or the plane 59 defined by the fins 56 having a non-parallel
orientation.
* * * * *