U.S. patent application number 16/428034 was filed with the patent office on 2019-10-17 for dynamic plate with inserts.
The applicant listed for this patent is K2M, Inc.. Invention is credited to Larry E. McClintock, Megan McMullen, Todd Wallenstein.
Application Number | 20190314062 16/428034 |
Document ID | / |
Family ID | 45890452 |
Filed Date | 2019-10-17 |
![](/patent/app/20190314062/US20190314062A1-20191017-D00000.png)
![](/patent/app/20190314062/US20190314062A1-20191017-D00001.png)
![](/patent/app/20190314062/US20190314062A1-20191017-D00002.png)
![](/patent/app/20190314062/US20190314062A1-20191017-D00003.png)
![](/patent/app/20190314062/US20190314062A1-20191017-D00004.png)
![](/patent/app/20190314062/US20190314062A1-20191017-D00005.png)
United States Patent
Application |
20190314062 |
Kind Code |
A1 |
Wallenstein; Todd ; et
al. |
October 17, 2019 |
Dynamic Plate With Inserts
Abstract
A spinal plate that is self-adjusting along its longitudinal
axis to accommodate subsidence that may occur and aid in loading
the bone graft to promote boney fusion while providing rigid
fixation. The spinal plate is configured to inhibit loosening or
backing out of bone screws.
Inventors: |
Wallenstein; Todd; (Ashburn,
VA) ; McMullen; Megan; (Leesburg, VA) ;
McClintock; Larry E.; (Gore, VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
K2M, Inc. |
Leesburg |
VA |
US |
|
|
Family ID: |
45890452 |
Appl. No.: |
16/428034 |
Filed: |
May 31, 2019 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13251622 |
Oct 3, 2011 |
10342583 |
|
|
16428034 |
|
|
|
|
61388639 |
Oct 1, 2010 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 17/8085 20130101;
A61B 17/7059 20130101; A61B 17/8023 20130101; A61B 17/8047
20130101; A61B 17/8009 20130101; A61B 17/1757 20130101 |
International
Class: |
A61B 17/70 20060101
A61B017/70; A61B 17/80 20060101 A61B017/80 |
Claims
1. A bone plate operatively attachable to bone comprising: a first
segment; and a second segment, the first and second segments
positioned along a longitudinal axis and movable relative to one
another; and a locking mechanism that inhibits relative axial
movement of the first and second segments along the longitudinal
axis toward one another and any non-axial movement of the first and
second segments relative to one another.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 13/251,622, filed on Oct. 3, 2011, which claims priority to,
and benefit of, U.S. Provisional Patent Application Serial No.
61/388,639, filed Oct. 1, 2010, the disclosures of which are hereby
incorporated by reference.
BACKGROUND
Technical Field
[0002] The present disclosure relates generally to a device for use
in orthopedic surgeries, and more particularly to a plate that is
attachable to the vertebrae, e.g., cervical vertebrae, and is
configured and adapted to change its length to maintain constant
loading of the vertebrae.
Background of Related Art
[0003] The human spinal column is a highly complex structure. It
includes twenty-four discrete bones, known as vertebrae, coupled
sequentially to one another to house and protect critical elements
of the nervous system. The cervical portion of the spine, which
comprises the neck of the spine up to the base of the skull,
includes the first seven vertebrae.
[0004] For many reasons, such as aging and trauma, the
intervertebral discs can begin to deteriorate and weaken. This may
result in chronic pain, degenerative disc disease, or even tearing
of the disc. Ultimately, the disc may deteriorate or weaken to the
point of tearing and herniation, in which the inner portions of the
disc protrude through the tear. A herniated disc may press against
or pinch the spinal nerves, thereby causing radiating pain,
numbness, and/or diminished strength or range of motion.
[0005] Many treatments are available to remedy these conditions,
including surgical procedures in which one or more damaged
intervertebral discs are removed and replaced with a prosthetic.
However, should the prosthetic protrude from between the adjacent
vertebrae and contact the surrounding nerves or tissues, the
patient may experience additional discomfort. In procedures for
remedying this problem, a spinal plate is affixed to the vertebrae
and oriented to minimize such protrusion. In addition, the plate
provides fixation and support to maintain spinal stability while
the fusion occurs.
[0006] Spinal plates, and cervical plates in particular, are known
in the art. Fixed cervical plates generally exhibit unalterable,
static dimensions. During the natural subsidence of the spinal
column after surgery, the overall length of the spinal column
gradually decreases. Fixed cervical plates resist this change due
to their fixed axial length, which may eventually stress the spine
and cause pain or discomfort. Adjustable cervical plates attend to
this predicament by providing a mechanism through which the plate
is shortened to accommodate for a measure of subsidence. However,
some adjustable plates require subsequent surgical procedures to
adjust the axial dimensions of the plate. In addition to
accommodating subsidence, it is critical for the plate to provide
means to apply constant loading of the bone graft in order to
promote fusion of the graft site.
[0007] A common problem associated with the use of spinal plates is
the tendency of the bone screws to "back out" or pull away or
otherwise withdraw from the bone into which they are mounted. This
problem occurs primarily due to the normal torsion and bending
motions of the body and spine. As the screws become loose and pull
away or withdraw from the bone, the heads of the screws can rise
above the surface of the spinal plate from one or more
vertebrae.
SUMMARY
[0008] Disclosed herein is a bone plate, e.g., cervical bone plate.
In an embodiment, the bone plate includes a plurality of segments,
each of which is operatively attachable to a vertebra. Each segment
is movable relative to at least one other segment for adjusting an
overall length of the plate without performing a secondary
procedure. This allows the bone plate to shorten in response to
subsidence, thereby facilitating constant loading of the bone
graft, which helps facilitate healing. The length of the plate
adjusts automatically in response to subsidence without requiring
additional manipulation, i.e., it occurs automatically. Lengthening
the plate necessitates a secondary user operation. The number of
segments that the plate includes corresponds to the number of
vertebral levels to be bridged. The plate includes at least two
segments that are positioned along a longitudinal axis and are
movable relative to one another along the longitudinal axis.
Movement of the segments apart from one another is inhibited. In
addition, non-axial movement, e.g., twisting or rotation, of the
segments relative to one another is inhibited.
[0009] Each segment is operatively attachable to a vertebra. Each
of the segments may include a bone screw hole for the reception of
a bone screw therethrough to operatively couple the segment to a
vertebral body. An insert may be placed between the portion of the
plate defining the screw hole and the screw to inhibit separation
of the screw from the plate. The insert, the plate, and the bone
screw may each be formed from materials having different hardnesses
to improve the retention of the screw to the plate.
[0010] A method of performing spinal surgery is disclosed. In use,
a plate is assembled having a number of movable segments that
corresponds to the number of vertebral levels that are to be
bridged. A bone plate including a first segment, and a second
segment, the first and second segments that are positioned along a
longitudinal axis and are movable relative to one another, wherein
movement of the segments apart from one another is inhibited is
provided. The first segment is secured to a first vertebra, and the
second segment is secured to the second vertebra, and the segments
are spaced to accommodate the patient's anatomy. During
implantation, inserts may be placed between segments to hold the
segments in a predetermined spaced orientation. When such inserts
are used, they are removed after implantation to permit movement of
the segments relative to one another.
[0011] These and other aspects of the present disclosure will be
described in greater detail when read with reference to the
appended figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Embodiments of the present disclosure are described herein
with reference to the accompanying figures, wherein:
[0013] FIG. 1 is a perspective view of a spinal fixation
assembly;
[0014] FIG. 2 is an exploded view of the spinal fixation assembly
of FIG. 1;
[0015] FIG. 3 is a top view of the spinal fixation assembly of FIG.
1;
[0016] FIG. 4 is a sectional view of the spinal fixation assembly
of FIG. 1 taken along section line 4-4;
[0017] FIG. 5 is a sectional view of a screw shown placed within a
portion of the spinal fixation assembly of FIG. 1; and
[0018] FIG. 6 is a perspective end view of one segment of the
spinal fixation assembly of FIG. 1 shown with screws.
DETAILED DESCRIPTION
[0019] Embodiments of the present disclosure will now be described
in detail with reference to the appended figures, wherein the
reference numerals identify similar or identical elements. In the
figures and in the following description, the term "proximal" will
refer to the device that is closest to the operator, while the term
"distal" will refer to the end of the device that is farthest from
the operator. In addition, the term "cephalad" is used in this
application to indicate a direction toward a patient's head,
whereas the term "caudad" indicates a direction toward the
patient's feet. Further still, for the purposes of this
application, the term "medial" indicates a direction toward a side
of the body of the patient, i.e., away from the middle of the body
of the patient. The term "posterior" indicates a direction toward
the patient's back, and the term "anterior" indicates a direction
toward the patient's front. Additionally, in the drawings and in
the description that follows, terms such as front, rear, upper,
lower, top, bottom, and similar directional terms are used simply
for convenience of description and are not intended to limit the
disclosure coupled hereto.
[0020] A plate 10 that allows for adjustment over a specified
range, while maintaining the strength and functionality of the
plate 10, will now be described with reference to FIGS. 1-6. The
plate 10 may generally be operatively coupled to a patient's spine,
and in particular to the cervical vertebrae, i.e., the vertebrae
comprising the patient's neck. The plate 10 includes a plurality of
adjacent segments that are axially movable relative to one another.
The number of segments that the plate 10 includes corresponds to
the number of vertebral levels the plate 10 is to bridge. As shown
in FIGS. 1-3, the plate 10 may include three (3) segments 12, 14,
16.
[0021] As shown best in FIGS. 1 and 3, the segments 12, 14, 16 of
the plate 10 include mating or inter-locking surfaces that fit
together in a dove-tail or tongue-and-groove mechanism, allowing
the segments 12, 14, 16 to move or slide relative to one another
along longitudinal axis "A" thereby facilitating lengthening or
shortening of the plate 10. As will be discussed, a locking
mechanism 18 inhibits lengthening of the plate 10, but facilitates
shortening of the plate 10 automatically, without an additional
procedure. As shown in FIG. 3, the segment 12 includes a groove 5
that is shaped to receive a portion 7 of adjacent segment 14, which
in turn includes a groove 9 that is shaped to receive a portion 11
of adjacent segment 16.
[0022] As shown best in FIG. 2, one or more rails 20 longitudinally
extend from the segments 12, 14 and are receivable within slots 27
of the adjacent segments 14, 16, respectively. The length of the
rails 20 (as well as the length of tongue 22 and number and
positioning of grooves 24a-c) determines the range within which the
segments 12, 14, 16 are slidable relative to one another. As shown
in FIG. 3, the rails 20 of segment 12 are slidably received within
segment 14; the rails 20 of segment 14 are slidably received within
segment 16. Although shown in the figures as having a circular
cross-section, the rail 20 may define an alternate geometrical
cross-section, e.g., the rail 20 may alternatively define a square
or triangular shape, an I-beam, a C-channel, or the like. The rails
20 may be operatively coupled to the segments 12, 14, 16 or may be
an integral portion of the segments 12, 14, 16.
[0023] The rails 20 facilitate movement of the segments 12, 14, 16
relative to one another along longitudinal axis "A", and also
stabilize the plate 10 by inhibiting movement of the segments 12,
14, 16 that is not along the longitudinal axis "A", e.g., rotation
and/or twisting. As the rails 20 are inserted into the channels 27
of the adjacent segments 14, 16, the locking mechanism 18 inhibits
the backward movement of the segments 12, 14, 16 away from one
another. By inhibiting the backward movement of the segments 12,
14, 16 away from one another, i.e., expansion of the plate 10, the
integrity and position of the plate 10 is maintained while allowing
compression of the anatomy, constant loading of the bone graft, and
subsidence of the anatomy, which may occur over time.
[0024] The locking mechanism 18 includes tongue 22 and grooves
24a-c. Once the rails 20 couple the segments 12, 14, 16 to one
another there is no additional manipulation required for the
locking mechanism 18 to be engaged, i.e., the locking mechanism 18
automatically releasably secures the segments 12, 14, 16 to each
other to prevent the segments 12, 14, 16 from moving apart while
permitting the segments 12, 14, 16 to move together. The tongues 22
and the rails 20 of the segments 12, 14 are slidably received
within segments 14, 16, respectively. As shown in FIG. 3, channels
27 receive rails 20. The rails 20 facilitate sliding of the tongue
22 of the locking mechanism 18 to slide relatively effortlessly
past the grooves 24a-c in a releasably locked engagement therewith,
i.e., as the tab 22a is engaged with one of the grooves 24a-c. The
tongue 22 may also include a guide channel 25b to receive a guide
pin 25a therein to facilitate aligning of the tongue 22 and to
minimize off-axis movement of the segments 12, 14, 16 relative to
one another.
[0025] The tongue 22 includes an undercut feature or tab 22a at a
distal end thereof is configured and adapted to engage the grooves
24a-c, thereby causing the tongue 22 to releasably lock to one of
the grooves 24a-c, which are spaced at intervals. As shown in FIG.
3, segment 12 and segment 14 can be maximally spaced apart by a
length x.sub.1, and segment 14 and segment 16 can be maximally
spaced apart by a length x.sub.2. The lengths x.sub.1, x.sub.2 by
which the segments 12, 14 and segments 14, 16 are spaced,
respectively, correspond to the groove 24a-c to which the tab 22a
of the tongue 22 is releasably secured. After installation, the
plate 10 is able to shorten in response to subsidence without the
need for a secondary operation, as the segments 12, 14, 16 move
together and the tab 22a of the tongue 22 moves into the next
adjacent groove 24b-c.
[0026] The interaction of the tab 22a with the grooves 24 allows
the segments 12, 14, 16 to move closer together but not apart,
i.e., once one of the grooves 24 engages the tab 22a, movement of
the segments 12, 14, 16 apart is inhibited. The shape of the tab
22a allows the tab 22a to disengage the groove 24 in a direction
that will move the segments 12, 14, 16 together, but not in a
direction that would move or distract the segments 12, 14, 16 apart
without requiring an additional, secondary user operation. If
needed, an instrument may be inserted into the groove 24 in which
the tab 22a is positioned to disengage the tab 22a from the groove
24, thereby releasing the locking mechanism 18 and allowing the
segments 12, 14, 16 to move apart from one another to allow for
surgical adjustment if it is needed. It is desirable to maintain
loading on the vertebral bodies so that the healing process, or
boney fusion, can continue uninterrupted. Inhibiting the segments
12, 14, 16 of the plate 10 from moving or distracting apart from
each other aids in the healing process by maintaining loading on
the vertebrae.
[0027] The plate 10 includes screw holes 28 adapted for the
reception of bone screws 40 (FIG. 6) therethrough. An insert 30 may
be press-fitted into each screw hole 28. In an embodiment, the
inserts 30 may be removable. The inserts 30 may be formed from a
material that is softer than that forming the bone screws 40. For
example, the insert 30 may be formed from commercially pure implant
grade titanium. An inward facing lip 31 is configured and adapted
to engage threads 41 of the bone screw 40. The harder material,
e.g., implant grade titanium alloy, of the bone screw 40 deforms
the softer material, e.g., commercially pure titanium, forming the
lip 31 of the insert 30. This engagement inhibits the screw from
migrating out of the plate 10, as well as the bone, as is described
in U.S. Patent Publication No. 2011/0106172 and U.S. Pat. No.
6,322,562, both of which are incorporated herein by reference.
Although the plate 10 is shown as having screw holes 28, it is
contemplated that a plate may be used that lacks holes 28. For
example, a plate may be attached to a bone by using screws that are
self-starting or self-tapping or drills may be used to prepare
holes within a plate for screws.
[0028] Other structures for locking screws to plates are known and
can be used. In addition, the inserts 30, although shown and
described as being part of the plate 10, may be used with a static
plate that does not include movable or adjustable segments. The
inserts 30 when used with a bone plate, whether adjustable or
static, would provide enhanced screw retention within the screw
holes of such plates.
[0029] As discussed, the screws 40 may be formed from a
biocompatible material. By way of example, the plate 10 may be
formed from a PEEK or titanium alloy, the inserts 30 formed from
commercially pure implant grade titanium, and the screws 40 formed
from a titanium alloy. The use of materials having different
characteristics, such as different hardness, facilitates
screw-plate engagement, and inhibits screw back out.
[0030] In an embodiment, the plate 10, locking mechanism 18, and
rails 20 are made from a relatively hard material, e.g., implant
grade titanium alloy, and the inserts 30 are made from a relatively
softer material, e.g., commercially pure implant grade titanium. In
another embodiment, the plate 10 and/or rails 20 may be made of
another implant grade material, such as, but not limited to,
commercially pure titanium, titanium alloys, cobalt chrome alloys,
PEEK, and the like.
[0031] In use, the segments 12, 14, 16 of the plate 10 may be
maximally spaced apart thereby facilitating the greatest degree of
adjustment to fit the anatomy of the patient. The tab 22a of tongue
22 may be received within the outward most groove 24a such that the
segments 12, 14, 16 are maximally spaced apart, but are inhibited
from moving apart from one another without a secondary user
operation to disengage the tab 22a from the groove 24a. The plate
10 is placed onto the vertebral bodies such that screw holes 28 are
located on the anterior portion of the most cranial vertebral body.
Screws 40 are placed into the two most cranial screw holes 28 to
anchor the plate 10 in place. The next adjacent segment is adjusted
to align the holes 28 with the next vertebral body so that the
screws 40 can be inserted through the holes 28 and into the
vertebral body. This process is repeated for each additional
vertebral segment.
[0032] A standard plate holder (not shown) can be used to
facilitate placement of the plate 10 and holding of the plate 10
during insertion of the screw 40. In addition, instruments known in
the art may be used to help expand or contract the adjacent
segments 12, 14, 16 during use. Removable wedges (not shown) may
hold segments 12, 14, 16 in a predetermined spaced orientation
during implantation by being positioned between the segments 12,
14, 16 and impeding movement of the segments 12, 14, 16 toward one
another in a predetermined spaced orientation during the
implantation of the plate 10. After implantation of plate 10, the
removable wedges are removed from the plate 10, thereby permitting
the segments 12, 14, 16 to move relative to one another after
surgery.
[0033] Each of the embodiments described above are provided for
illustrative purposes only. It will be understood that various
modifications may be made to the embodiments of the present
disclosure. Therefore, the above description should not be
construed as limiting, but merely as exemplifications of
embodiments. Those skilled in the art will envision other
modifications within the scope and spirit of the present
disclosure.
* * * * *