U.S. patent application number 13/042074 was filed with the patent office on 2012-09-13 for fastener retention system for spinal plates.
This patent application is currently assigned to Tyler HOLSCHLAG. Invention is credited to Tyler HOLSCHLAG.
Application Number | 20120232595 13/042074 |
Document ID | / |
Family ID | 46796663 |
Filed Date | 2012-09-13 |
United States Patent
Application |
20120232595 |
Kind Code |
A1 |
HOLSCHLAG; Tyler |
September 13, 2012 |
FASTENER RETENTION SYSTEM FOR SPINAL PLATES
Abstract
A fastener retention system for retaining fasteners within
apertures of an orthopedic plate includes a first pocket disposed
between two of the apertures in the plate, a blocking member
disposed between the two apertures and including a second pocket
that forms a cavity with the first pocket, and a spring that
expands from a compressed configuration within the first pocket to
a decompressed configuration within the cavity.
Inventors: |
HOLSCHLAG; Tyler;
(Oceanside, CA) |
Assignee: |
HOLSCHLAG; Tyler
Oceanside
CA
|
Family ID: |
46796663 |
Appl. No.: |
13/042074 |
Filed: |
March 7, 2011 |
Current U.S.
Class: |
606/280 |
Current CPC
Class: |
A61B 17/7059 20130101;
A61B 17/8061 20130101; A61B 17/8023 20130101; A61B 17/8042
20130101 |
Class at
Publication: |
606/280 |
International
Class: |
A61B 17/80 20060101
A61B017/80 |
Claims
1. A fastener retention system for retaining fasteners within
apertures of an orthopedic plate, comprising: a first pocket
disposed between two of the apertures in the plate; a blocking
member disposed between the two apertures and including a second
pocket that forms a cavity with the first pocket; and a spring that
expands from a compressed configuration within the first pocket to
a decompressed configuration within the cavity.
2. The system of claim 1, wherein the spring includes a height that
is less than or equal to a depth of the first pocket when in the
compressed configuration.
3. The system of claim 1, wherein the spring includes a height that
is greater than a depth of the first pocket when in the
decompressed configuration.
4. The system of claim 1, wherein the spring includes a plurality
of flexible resilient members coupled by a plurality of hubs.
5. The system of claim 1, wherein the spring includes a radius of
curvature in the decompressed configuration.
6. The system of claim 1, wherein the spring includes a central hub
that contacts a surface of the first pocket in the compressed
configuration and a surface of the second pocket in the
decompressed configuration.
7. The system of claim 1, wherein the spring is further configured
to bias the blocking member to protrude into at least one of the
two apertures.
8. The system of claim 1, wherein the first pocket is disposed in a
channel extending between the two apertures in the plate and
includes a first depth D1.
9. The system of claim 8, wherein the blocking member is disposed
in the channel and the second pocket includes a second depth
D2.
10. The system of claim 9, wherein the spring is configured to
compress to a first height H1 that is less than or equal to D1 when
a first force is applied to the spring and expand to a second
height H2 that is greater than D1 and less than or equal to the
combined depth of D1 and D2 when the first force is released.
11. The system of claim 10, wherein the spring is further
configured to engage with a portion of the blocking member when the
first force is released and compress from a first length L1 to a
second length L2 when a second force is applied to the blocking
member.
12. A system for bone fixation comprising: an orthopedic plate
having apertures configured to receive fasteners and a first pocket
formed in a channel between two of the apertures; a blocking member
that slides in the channel and includes a second pocket, wherein
the first and second pockets form a cavity between the blocking
member and the orthopedic plate; and a spring that expands from a
compressed configuration, wherein a height of the spring is less
than or equal to a depth of the first pocket, to a decompressed
configuration, wherein the height of the spring is greater than the
depth of the first pocket.
13. The system of claim 12, wherein a first portion of the spring
is configured to engage a wall of the second pocket in the
decompressed configuration.
14. The system of claim 12, wherein a second portion of the spring
is configured to engage a wall of the first pocket in the
decompressed configuration.
15. The system of claim 12, wherein the spring biases the blocking
member towards a top surface of the orthopedic plate in the
decompressed configuration.
16. The system of claim 12, wherein the spring biases the blocking
member towards a rest position substantially equidistant from the
two apertures in the decompressed configuration.
17. The system of claim 12, wherein the spring includes a radius of
curvature in the decompressed configuration that is less than a
radius of curvature in the compressed configuration.
18. A method comprising: inserting a spring into a first pocket in
a channel of a plate; inserting a blocking member having a second
pocket into the channel of the plate; positioning the blocking
member to align the second pocket and the first pocket forming a
cavity; and expanding the spring to fill the cavity.
19. The method of claim 18, further comprising: inserting a first
screw into a first aperture adjacent to the first pocket to secure
the plate to a vertebra; positioning the blocking member towards a
second aperture that is opposite the first aperture and adjacent to
the first pocket using the first screw, wherein the spring
compresses; and decompressing the spring to bias the blocking
member to align the second pocket and the first pocket.
20. The method of claim 19, further comprising: inserting a second
screw into the second aperture to secure the plate to the vertebra;
positioning the blocking member towards the first aperture using
the second screw, wherein the spring compresses; and decompressing
the spring to bias the blocking member to align the second pocket
and the first pocket.
Description
FIELD
[0001] The present disclosure generally relates to the field of
spinal orthopedics, and more particularly to fastener retention
systems for spinal plates.
BACKGROUND
[0002] The background description provided herein is for the
purpose of generally presenting the context of the disclosure. Work
of the presently named inventors, to the extent it is described in
this background section, as well as aspects of the description that
may not otherwise qualify as prior art at the time of filing, are
neither expressly nor impliedly admitted as prior art against the
present disclosure.
[0003] The spine is a flexible column formed of a plurality of
bones called vertebrae. The vertebrae include a hollow cavity and
essentially stack one upon the other, forming a strong column for
support of the cranium and trunk of the body. The hollow core of
the spine houses and protects the nerves of the spinal cord. The
different vertebrae are connected to one another by means of
articular processes and intervertebral, fibrocartilaginous bodies.
The intervertebral bodies, also known as intervertebral disks,
include a fibrous ring filled with pulpy material. The disks
function as spinal shock absorbers and also cooperate with synovial
joints to facilitate movement and maintain flexibility of the
spine. When one or more disks degenerate through accident or
disease, nerves passing near the affected area may be compressed
and consequently irritated. The result may be chronic and/or
debilitating neck and/or back pain due to these spinal
disorders.
[0004] One procedure for treating spinal disorders involves using
substantially rigid plates for fixation of two or more vertebrae in
desired spatial relationships and orientations relative to each
other. During the procedure, the spine can be approached anteriorly
or posteriorly. In either case, holes are drilled and tapped in at
least two of the vertebrae to receive screws or other fasteners
that secure the plate. The holes are positioned with reference to
apertures formed in the plate. Typically the plate is curved about
its longitudinal axis to facilitate contiguous surface engagement
of the plate with the vertebrae. With the plate maintained against
the vertebrae, the fasteners are driven into the vertebrae through
the apertures in the plate. As a result, the plate maintains the
attached vertebrae in a desired spacing and orientation with
respect to each other.
[0005] Over time, some fasteners may gradually work loose from the
vertebrae. Slight shock or vibration of the vertebrae, due to
walking, climbing stairs or more vigorous activity by the patient
following treatment increases this tendency, jeopardizing the
integrity of fixation. Moreover, as the fasteners work loose, the
outward protrusion of the heads over other components of the
fasteners can be a source of discomfort and present the risk of
trauma to adjacent and surrounding soft tissue. Some plates include
a retention mechanism that prevents the screws from working loose
after fixation.
[0006] Occasionally, the fasteners may not be inserted at a proper
insertion angle during the fixation procedure. When the fastener is
inserted at an improper angle, the retention mechanism may not be
able to contact the fastener as the fastener backs away from the
vertebra. The retention mechanism may increase the complexity of
manufacturing and assembly. For example, the spinal plate may
require features such as additional openings in the plate to
assemble the retention mechanism. These openings may decrease the
structural integrity of the plate. The retention mechanism may
require various features that interact with springs or other
compression members that bias the retention mechanism in one or
more directions. Additional features such as stops that prevent the
retention mechanism from moving too far relative to the plate or
from over-compressing the springs may also complicate manufacture
and assembly.
SUMMARY
[0007] A fastener retention system for retaining fasteners within
apertures of an orthopedic plate includes a first pocket disposed
between two of the apertures in the plate, a blocking member
disposed between the two apertures and including a second pocket
that forms a cavity with the first pocket, and a spring that
expands from a compressed configuration within the first pocket to
a decompressed configuration within the cavity.
[0008] In other features, the spring includes a height that is less
than or equal to a depth of the first pocket when in the compressed
configuration. The spring includes a height that is greater than a
depth of the first pocket when in the decompressed configuration.
The spring includes a plurality of flexible resilient members
coupled by a plurality of hubs. The spring includes a radius of
curvature in the decompressed configuration. The spring includes a
central hub that contacts a surface of the first pocket in the
compressed configuration and a surface of the second pocket in the
decompressed configuration. The spring is further configured to
bias the blocking member to protrude into at least one of the two
apertures.
[0009] In still other features, the first pocket is disposed in a
channel extending between the two apertures in the plate and
includes a first depth D1. The blocking member is disposed in the
channel and the second pocket includes a second depth D2. The
spring is configured to compress to a first height H1 that is less
than or equal to D1 when a first force is applied to the spring and
expand to a second height H2 that is greater than D1 and less than
or equal to the combined depth of D1 and D2 when the first force is
released. The spring is further configured to engage with a portion
of the blocking member when the first force is released and
compress from a first length L1 to a second length L2 when a second
force is applied to the blocking member.
[0010] A system for bone fixation includes an orthopedic plate
having apertures configured to receive fasteners and a first pocket
formed in a channel between two of the apertures, a blocking member
that slides in the channel and includes a second pocket, wherein
the first and second pockets form a cavity between the blocking
member and the orthopedic plate, and a spring that expands from a
compressed configuration, wherein a height of the spring is less
than or equal to a depth of the first pocket, to a decompressed
configuration, wherein the height of the spring is greater than the
depth of the first pocket.
[0011] In other features, a first portion of the spring is
configured to engage a wall of the second pocket in the
decompressed configuration. A second portion of the spring is
configured to engage a wall of the first pocket in the decompressed
configuration. The spring biases the blocking member towards a top
surface of the orthopedic plate in the decompressed configuration.
The spring biases the blocking member towards a rest position
substantially equidistant from the two apertures in the
decompressed configuration. The spring includes a radius of
curvature in the decompressed configuration that is less than a
radius of curvature in the compressed configuration.
[0012] A method includes the steps of inserting a spring into a
first pocket in a channel of a plate, inserting a blocking member
having a second pocket into the channel of the plate, positioning
the blocking member to align the second pocket and the first pocket
forming a cavity, and expanding the spring to fill the cavity.
[0013] In other features, the method further comprises the steps of
inserting a first screw into a first aperture adjacent to the first
pocket to secure the plate to a vertebra, positioning the blocking
member towards a second aperture that is opposite the first
aperture and adjacent to the first pocket using the first screw,
wherein the spring compresses, and decompressing the spring to bias
the blocking member to align the second pocket and the first
pocket.
[0014] In still other features, the method further comprises the
steps of inserting a second screw into the second aperture to
secure the plate to the vertebra, positioning the blocking member
towards the first aperture using the second screw, wherein the
spring compresses, and decompressing the spring to bias the
blocking member to align the second pocket and the first
pocket.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a perspective view of a spinal plate and a
fastener retention system according to the principles of the
present disclosure.
[0016] FIG. 2A is a partial perspective view of the spinal plate
according to the principles of the present disclosure.
[0017] FIG. 2B is a partial perspective view illustrating assembly
of the spinal plate and the fastener retention system according to
the principles of the present disclosure.
[0018] FIG. 2C is a partial perspective view of the spinal plate
and the fastener retention system according to the principles of
the present disclosure.
[0019] FIG. 3 is a perspective view of a spring of the fastener
retention system according to the principles of the present
disclosure.
[0020] FIG. 4A is an elevational top view of the spring in a first
decompressed position according to the principles of the present
disclosure.
[0021] FIG. 4B is an elevational top view of the spring in a first
compressed position according to the principles of the present
disclosure.
[0022] FIG. 5 is an elevational side view of the spring according
to the principles of the present disclosure
[0023] FIG. 6A is an elevational side view of the spring in a
second decompressed position according to the principles of the
present disclosure.
[0024] FIG. 6B is an elevational side view of the spring in a
second compressed position according to the principles of the
present disclosure.
[0025] FIG. 7A is a cross-sectional view of the spinal plate and
the fastener retention system illustrating the spring in the second
compressed position according to the principles of the present
disclosure.
[0026] FIG. 7B is a cross-sectional view of the spinal plate and
the fastener retention system illustrating the spring in the first
and second decompressed positions according to the principles of
the present disclosure.
[0027] FIG. 7C is a cross-sectional view of the spinal plate and
fastener retention system illustrating the spring in the first
compressed position according to the principles of the present
disclosure.
DETAILED DESCRIPTION
[0028] The following description is merely exemplary in nature and
is in no way intended to limit the disclosure, its application, or
uses. For purposes of clarity, the same reference numbers will be
used in the drawings to identify similar elements. As used herein,
the phrase at least one of A, B, and C should be construed to mean
a logical (A or B or C), using a non-exclusive logical or. It
should be understood that steps within a method may be executed in
different order without altering the principles of the present
disclosure.
[0029] Embodiments of the invention will now be described with
reference to the Figures, wherein like numerals reflect like
elements throughout. Embodiments of the invention may include
several novel features, no single one of which is solely
responsible for its desirable attributes or which is essential to
practicing the invention described herein. The words proximal and
distal are applied herein to denote specific ends of components of
the instrument described herein. For example only, a proximal end
refers to the end of an instrument nearer to an operator of the
instrument when the instrument is being used. A distal end refers
to the end of a component further from the operator and extending
towards the surgical area of a patient and/or the implant.
Similarly, the words left and right, top and bottom, and upper and
lower may denote opposite sides of a component.
[0030] Accordingly, a fastener retention mechanism for spinal
plates of the present disclosure includes a blocking member and a
spring that is compressible in multiple directions. The retention
mechanism includes features that enable greater intrusion of the
blocking member into the apertures to prevent fastener back-out
from the vertebrae. The configuration of the spinal plate enables
top-loading of the spring into a pocket of the spinal plate. The
spring may be compressed in a first direction prior to insertion
into the pocket of the plate. The blocking member may slide in
place over the compressed spring. When the spring decompresses, the
spring may fill the pocket and a cavity of the blocking member,
thus enclosing the spring therebetween. The blocking member may
slide towards a first one of two apertures to enable insertion of a
fastener within a second one of the apertures. As the blocking
member slides relative to the plate, the spring may compress in a
second direction and bias the blocking member back to a rest
position in which a portion of the blocking member intrudes upon
the two apertures.
[0031] Referring now to FIG. 1, a spinal plate 100 includes
apertures 102 that receive fasteners or bone screws 104 for
attachment to two or more vertebrae (not shown.) The plate 100 may
be, for example, a cervical plate that is configured for attachment
to three cervical vertebrae. The plate 100 may be formed from a
variety of materials such as physiologically inert metals, alloys,
and/or plastics. For example, the plate 100 may be formed from a
titanium and/or titanium-based alloy. The plate 100 is
substantially symmetrical about a center line 106 that passes along
a longitudinal axis of the plate 100. A surgeon may position the
plate 100 over the vertebrae to be fixed and drill and tap holes in
the vertebrae to receive the screws 104. In other examples, the
screws 104 may be self-tapping. Each head 108 of the screws 104
includes a driving feature such as hexagonal or star configuration
that enables the surgeon to begin to drive the screws 104 into the
vertebrae. As the screws 104 advance further into the vertebrae,
the heads 108 sink deeper into the apertures 102.
[0032] A retention mechanism 110, disposed between a first aperture
102a and a second aperture 102b, may be used to prevent a
corresponding first screw 104a and a corresponding second screw
104b from backing away from the plate 100 should either become
loose. As illustrated in FIG. 1, the apertures 102 may be formed in
pairs along the center line 106. Each pair of the apertures 102 may
include a corresponding retention mechanism. When the retention
mechanism 110 is in a rest position or a locked position, as shown
in FIG. 1, a portion of the retention mechanism 110 intrudes upon
both apertures 102a and 102b. Thus, if a screw should become loose
and back away from the vertebra, the head 108 contacts the
retention mechanism 110 preventing the screw from backing out any
further from the vertebra.
[0033] In FIG. 2A, a channel 112 formed in the plate 100
communicates with the first aperture 102a and the second aperture
102b. The channel 112 may run perpendicular to the center line 106.
The channel 112 may include grooves 114 that are configured to
slidably receive a blocking member 116 as shown in FIGS. 2B and 2C.
For example, each of the grooves 114 may include a cantilevered
projection or edge that extends from a top surface 118 of the plate
100 and over a portion of the channel 112. The blocking member 116
may include beveled edges 120 that form a substantially trapezoidal
cross-section. The beveled edges 120 mate with the grooves 114 to
prevent the blocking member 116 from exiting the channel 112 while
allowing the blocking member 116 to slide substantially parallel to
a lateral line 122 that is substantially perpendicular to the
centerline 106.
[0034] Continuing with FIG. 2A, a pocket 123 may be formed in the
channel 112. The pocket 123 may include a depression in the channel
112. The pocket 123 may include a length and width that form
substantially a rectangular shape and include a depth D1 that is
substantially less than an overall thickness of the plate 100, as
shown in FIG. 6B. Referring now to FIGS. 2B and 2C, the retention
mechanism includes a spring 124 that may be configured to rest
within the pocket 123. The spring 124 may be compressible in
multiple directions. For example, the spring 124 may include
elements similar to an accordion spring that enable compression in
a first direction along the lateral line 122 when a first force F1
is applied as shown in FIG. 4B. The spring 124 may also include
elements similar to a leaf spring that enable compression in a
second direction along a perpendicular line 126 that is
perpendicular to both the center line 106 and the lateral line 122
when a force F2 is applied as shown in FIG. 6B.
[0035] The spring 124 may be formed from a variety of materials
such as physiologically inert metals, alloys, and/or plastics. In
other examples, the spring 124 may be formed from other materials
that may not be physiologically inert because the spring 124 may be
segregated from bone and/or tissue by the pocket 122 and the
blocking member 116 as described below with reference to FIGS.
7A-7C.
[0036] Continuing now with FIGS. 3-5, the spring 124 may include
various features that enable compression in the first direction
that is substantially parallel to the lateral line 122. For
example, the shape of the spring 124 may be substantially
symmetrical about the lateral line 122 and perpendicular to the
lateral line 122 along a right surface 128 and a left surface 130
of a central hub 132. A left upper rib 134, a left lower rib 136, a
right upper rib 138, and a right lower rib 140 extend from each
central hub 132 in a symmetrical fashion about lateral line 120.
The ribs may be configured in a substantially linear fashion.
Alternatively, the ribs may include some bends and/or some
curvature. From left to right as depicted in FIG. 4A, each upper
right rib 138 is coupled with each adjacent upper left rib 134 to
form an upper hub 142, and each lower right rib 140 is coupled with
each adjacent lower left rib 136 to form a lower hub 144. The
leftmost and rightmost upper and lower ribs may not couple with
adjacent ribs and instead may form end caps 146 and 147 of the
spring 124.
[0037] Thus, each central hub 132 with a set of ribs 134, 136, 138,
140 may substantially form a resilient member that couples with an
adjacent resilient member at the upper and lower hubs 142 and 144.
For example, each resilient member may resemble an X-shaped member.
In other examples, various suitably-shaped resilient members may be
used to form various springs. For example, the spring may comprise
substantially elliptically-shaped resilient members. The spring 124
may also comprise non-symmetrically-shaped resilient members. That
is, the spring may comprise S-shaped resilient members, diagonal
resilient members, and the like. In an uncompressed or decompressed
configuration, such as when the spring 124 biases the blocking
member 116 to the rest position, the spring 124 includes a length
L1 that substantially fills the pocket 123 as shown in FIG. 4A.
[0038] Referring now to FIG. 4B, as the force F1 is applied on the
end cap 146, the spring 124 will deflect in a linear and consistent
manner until it cannot bend any further, at a point where the
entire right surface 128 of one central hub 132 may be in contact
with the entire left surface 130 of the next adjacent central hub
132. In this compressed configuration, the spring 124 includes a
length L2 that is less than L1. The stiffness of the spring 124 may
vary greatly as a function of the width, depth, thickness, material
composition, and number of ribs and hubs within the spring 124.
Thus, the spring 124 is compressible in a first direction that is
substantially parallel to the lateral line 122. Furthermore, the
spring 124 is self-limiting as the right surface 128 and left
surface 130 contact one another thus preventing further compression
due to the force F1. The spring 124 may include other self-limiting
features, such as projections 148 on bottom portions of the end
caps 146 and 147. The projections 148 may contact the upper and
lower hubs 142 and 144 when the spring 124 is in the compressed
configuration.
[0039] Referring now to FIGS. 6A-6B, the shape of the spring 124
may include various features that enable compression in the second
direction that is substantially parallel to the perpendicular line
126. For example, the spring 124 may include curvature of radius R
applied to each resilient member. That is, the entire spring 124
from end cap 146 to end cap 147 may include curvature of radius R
similar to a leaf spring as shown in FIG. 3. In other examples,
each resilient member may include one or more curves or bends that
substantially form a curved or angled profile. The curves or bends
may be formed in a plane that is substantially parallel to a plane
formed by the perpendicular line 126 and the center line 122.
[0040] Referring now to FIG. 6B, as a force F2 is applied to a top
surface 150 of the spring 124, the spring 124 will deflect in a
linear and consistent manner until it cannot bend any further, at a
point where a bottom surface 152 of the spring 124 is substantially
parallel to and/or contacts a base surface 154 of the pocket 123.
In an uncompressed or decompressed configuration, the spring 124
may include a height H1. As the force F2 is applied, the spring 124
may be compressed to a height H2 that is less than H1.
[0041] Referring now to FIGS. 7A-7C, partial cross-sectional views
of the plate 100 and retention mechanism 110 illustrate interaction
of the spring 124 with the plate 100 and the blocking member 116.
In FIG. 7A, the spring 124 may be compressed to the height H2 so
that the blocking member 116 may slide into place in the channel
112. For example, the force F2 may be applied to compress the
spring 124 until the bottom surface 152 of the spring 124 is
substantially parallel to or in contact with the base surface 154
of the pocket 123 as illustrated in FIG. 6B. That is, the spring
124 may be compressed until the height H2 is less than or equal to
the depth D1 of the pocket 123. Once the blocking member 116 is
centered over the pocket 123, a cavity 156 may be formed by a
second pocket 158 in the blocking member 116 and the first pocket
123 of the plate 100. The second pocket 158 may include a depth
D2.
[0042] Referring now to FIG. 7B, as the force F2 decreases, the
spring 124 expands to fill the cavity 156 until the top surface 150
of the spring contacts the pocket 158 of the blocking member 116.
That is, the spring 124 may decompress until the height H2 is
greater than the depth D1 and less than the combined depth D1 and
depth D2. In another example, the spring 124 may include material
properties that enable the spring 124 to be flattened prior to
loading within the pocket 123. For example, the spring 124 may
include the radius of curvature R at one temperature and be
flattened by increasing or decreasing the temperature of the spring
124 to a second temperature. That is, the spring 124 may comprise
materials such as nickel titanium, commonly referred to as nitinol,
that include shape memory and super elastic properties based on the
temperature of the materials. Once the spring 124 has been
flattened and loaded within the pocket 122, the blocking member 116
may be slid into place above the pocket 123 as described with
reference to FIG. 7A. The temperature of the spring 124 may then be
increased or decreased as necessary to regain the curved shape such
that the spring 124 fills the cavity 156.
[0043] In FIG. 7C, the retention mechanism 110 moves to the first
open position when the force F1 is applied, for example, by the
head 108 of the first screw 104a being inserted into the first
aperture 102a (not shown). An engagement portion 160 of the
blocking member 116 engages a top portion 162 of the end cap 146 of
the spring 124. A bottom portion 164 of the end cap 147 engages a
side wall 166 of the pocket 122. Thus, as the force F1 is applied,
the spring 124 begins to compress in the second direction from
length L1 to length L2. Similarly, the force F1 may be applied in
the opposite direction, for example, by the head 108 of the second
screw 104b being inserted into the second aperture 102b (not
shown). The retention mechanism 110 moves to a second open
position. As the force F1 decreases, the spring 124 biases the
blocking member 116 towards the rest or locked position and the
length of the spring 124 returns to length L1.
[0044] Example embodiments of the methods and systems of the
present invention have been described herein. As noted elsewhere,
these example embodiments have been described for illustrative
purposes only, and are not limiting. Other embodiments are possible
and are covered by the invention. Such embodiments will be apparent
to persons skilled in the relevant art(s) based on the teachings
contained herein. Thus, the breadth and scope of the present
invention should not be limited by any of the above-described
exemplary embodiments but should be defined only in accordance with
the following claims and their equivalents. The broad teachings of
the disclosure can be implemented in a variety of forms. Therefore,
while this disclosure includes particular examples, the true scope
of the disclosure should not be so limited since other
modifications will become apparent to the skilled practitioner upon
a study of the drawings, the specification, and the following
claims.
* * * * *