Note: Descriptions are shown in the official language in which they were submitted.
CA 02691279 2010-01-27
Attorney Docket No. 10139/19902
System and Method for Minimally Invasive Clavicle Plate Application
Inventor: Jonas Andermahr, Flora Mauch, Claudia Reichle and Philipp Brun
Background
[0001] Clavicle fractures are the second most frequently occurring fractures
in humans.
Osteosynthesis procedures at the clavicle shaft generally require the
insertion of a bone plate through an
incision approximately 10 - 15 cm. in length. The size of the incision
presents numerous complications
including post-operative scarring and irritative complications arising from
contact of the procedure site
with items of clothing, backpacks, etc. Furthermore, current clavicle fixation
procedures employ Recon
plates, which often do not provide adequate stability to a fractured clavicle,
sometimes requiring the
insertion of a second bone plate to achieve the required stability.
Summary of the Invention
[0002] The present invention is directed to a bone fixation plate comprising
an elongated body
contoured to conform to the anatomy of a clavicle, the elongated body
comprising a head at a first end
and a shaft extending therefrom to a second end, the second end further
comprising a reduced diameter
tapered tip configured to permit insertion of the elongate body through a
minimally invasive incision
formed adjacent the clavicle. The bone fixation plate also comprises a first
plate hole extending through
the shaft from a proximal face to a distal face, the first plate hole formed
as a combination hole and a
second plate hole extending through the head from the proximal face to the
distal face, the second plate
hole being threaded.
Brief Description of the Drawings
[0003] Fig. 1 shows a first perspective view of a bone plate according to a
first embodiment of the
present invention positioned against a clavicle;
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Attorney Docket No. 10139/19902
Fig. 2 shows a second perspective view of the bone plate of Fig. 1;
Fig. 3 shows a zoomed perspective view of a plate hole of the bone plate of
Fig. 1;
Fig. 4 shows a drill guide for forming a bore in a bone according to a first
method of the present
invention;
Fig. 5 shows a drill guide for forming a bore in a bone according to a second
method of the
present invention;
Fig. 6 shows a perspective view of the bone plate of Fig. 1 after being
twisted by a bending
rod;
Fig. 7 shows a perspective view of a bone plate according to a second
embodiment of the
present invention; and
Fig. 8 shows a perspective view of a bone plate according to a third
embodiment of the present
invention.
Detailed Description
[0004] The present invention is directed to a system and method for minimally
invasive fixation of
clavicle fractures in living bodies. Specifically, the present invention is
directed to a system including a
bone plate having a plurality of angled bone plate holes and combination plate
holes configured to
permit an angled inserted of bone screws therethrough. As described in more
detail below, a first
exemplary bone plate according to the present invention comprises an elongated
body with a lateral
extension at a first end thereof where a width of the lateral extension (i.e.,
an extent of the lateral
extension in a direction substantially perpendicular to a longitudinal axis of
the elongated body) is
greater than the width of the elongated body. A second end of this bone plate
comprises a tapered tip
configured to minimize trauma to adjacent soft tissue as the bone plate is
guided through the minimally
invasive incision to a target position against the clavicle. In an exemplary
embodiment, the minimally
invasive incision is approximately 1 - 3 cm. in length and, in a preferred
embodiment, is approximately 2
cm long. A second exemplary bone plate according to the present invention
includes an elongated
body without any lateral extensions, wherein the elongated body has a uniform
width and tapered tips at
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Attorney Docket No. 10139/19902
both ends thereof, as will be described in greater detail hereinafter. As used
in this application, the term
proximal refers to a direction approaching a physician or other user of the
device and the term distal
refers to a direction along the device extending away from the user. In an
operative configuration, a
distal face of the bone plate of the present invention is seated against the
clavicle while the proximal face
faces away from the clavicle.
[0005] Fig. 1 shows a bone plate 100 according to a first exemplary embodiment
of the invention.
The bone plate 100 is an elongated element comprising a lateral extension 102
at a first end and a shaft
104 of substantially uniform width extending therefrom in a second direction.
However, those skilled in
the art will recognize that the plate 100 may be formed in any dimensions
suitable to the patients
anatomy. The shaft 104 comprises a plurality of fixation element holes 106
extending therethrough from
a proximal face 108 to a distal face 110 which, when the plate 100 is applied
to a bone in a desired
configuration, faces the bone 10. The holes 106 are spaced from one another
along a longitudinal axis
of the shaft and extend substantially along a centerline of the bone plate
100. In an exemplary
embodiment, at least 2 of the plate holes 106 are combination holes with a
first substantially circular
hole 112 overlapping a second substantially circular hole 114 and open to each
other. In a preferred
embodiment, a diameter of the first hole 112 is substantially equivalent to a
diameter of the second hole
114, wtih the diameter of the second hole 114 being selected to threadedly
engage the threaded head
of a bone screw 20 inserted therethrough. In a preferred embodiment, each of
the first and second
holes 112, 114 are approximately 3.5 mm. in diameter. The first hole 112 may
be formed with a
smooth outer wall with a substantially cylindrical portion 116 extending
perpendicularly from the
proximal face 108 to the distal face 110. As shown in greater detail in Fig.
3, the first hole 112 also
comprises a tapered portion 118 extending distally thereinto from the proximal
face 108 by a
predetermined distance. The tapered portion 118 has a greater diameter than
the cylindrical portion
116 to permit an angularly stable insertion of the bone screw 20 into the
plate hole 106 while also
seating a head 22 of the bone screw 20 therein, as will be described in
greater detail later on. The
second hole 114 comprises a tapered portion 120 extending distally from the
proximal face 106 by a
predetermined distance to a substantially cylindrical threaded portion 122.
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Attorney Docket No. 10139/19902
[0006] Those skilled in the art will understand that the use of a combination
plate hole 106 offers the
advantage of permitting selective use of a compression screw or an angularly
stable locking screw by
inserting the bone screw 20 into either the first hole 112 or the second hole
114. Specifically, the bone
screw 20 may be inserted through the first hole 112 at an angle suited to the
dimensions of the bone 10
and the location of a fracture 12 thereof to maximize dynamic-axial
compression. Alternatively, the
bone screw 20 may be inserted through the second hole 114 at an angle relative
to an axis of the
second hole 114 selected by the user so that the screw head 22 is stably
seated with a threaded portion
thereof threadedly engaging the cylindrical portion 122 and screwed into the
bone 10 without a loss of
reduction. Thus the user can select the angle of insertion of the bone screw
20 to ensure good bony
purchase to the bone screw 20 to stabilize a bone with multifragment fractures
or osteoporotic bone. It
is noted that although only three bone plate hole 106 are shown in the present
embodiment, any number
of bone plate holes 106 may be employed in the shaft 104 without deviating
from the scope of the
present invention. A length of the bone plate 100 along the longitudinal axis
thereof may range from
approximately 69 mm. when three plate holes 106 are used to approximately 135
mm. when 8 plate
holes are used, although it is noted that any other combination of dimensions
and quantity of plate holes
106 may be employed without deviating from the scope of the present invention
as dictated, for
example, by the anatomy of the patient being treated. The exemplary bone plate
shown in Figs. 1 - 2 is
configured for positioning over an anterior face of a left clavicle. As would
be understood by those
skilled in the art, the dimensions and orientation of the bone plate 100 may
be varied as necessary to
suit the anatomy of a particular patient and/or of a particular part of the
clavicle being treated. For
example, if the procedure is being performed on an anterior face of a right
clavicle, the positions of the
lateral extension 102 and the shaft 104 may be reversed so that the shaft 104
lies medial to the lateral
extension 102 in an operative configuration. The bone plate 100 may also be
provided with a
positioning inscription 128 to indicate any or all of a proper position on the
clavicle for which the bone
plate 100 is suited as well as a desired orientation of the bone plate 100 on
the target portion of the
clavicle, as those skilled in the art will understand. Specifically, the
positioning inscription 128 may
comprise an arrow and a textual indicator with a proper orientation of the
bone plate 100 being
indicated by, for example, an upright position of the textual indicator. The
positioning inscription 128
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Attorney Docket No. 10139/19902
may be located anywhere on the bone plate 100 without deviating from the scope
of the present
invention.
[0007] The shaft 104 also comprises a plurality of arc-shaped cutouts 124,
cross-sectional shapes
thereof resembling a part of a circle. The cut-outs 124 are configured to
allow any necessary plate
contouring by defining weakened portion of the bone plate 100 which may be
bent as needed to
conform the shape of the bone plate 100 to a shape of the bone 10, as will be
described in greater
detail later on. In an exemplary embodiment, the cut-outs 124 are located
between adjacent ones of
the plate holes 106. In addition, the bone plate 100 may be formed with a
rounded profile to prevent
trauma to adjacent soft tissue when implanted on the bone 10. Specifically, as
shown in Figs. 1 and 2,
an outer perimeter of the bone plate 100 and a cross-sectional profile of the
bone plate 100 are
substantially rounded. In addition, the distal face 110 may be provided with
undercuts (not shown) to
reduce an area of contact between the bone plate 100 and the bone 10, thus
reducing the impairment
of blood supply, as those skilled in the art will understand.
[0008] The lateral extension 102, which, as described earlier has a width
(i.e., an extent in a direction
perpendicular to the longitudinal axis of the plate 100) greater than that of
the shaft 104, is configured
for placement over a lateral end of the clavicle 10. That is, the lateral
extension 102 is shaped and
positioned so that, when the plate 100 is placed on the bone 10 in a desired
location, the lateral
extension 102 overlies a target region of the lateral end of the clavicle 10
with a plurality of lateral plate
holes 126 distributed along two axes extending substantially parallel to the
longitudinal axis of the bone
plate 100. It is noted however that the lateral plate holes 126 may be
distributed over the lateral
extension 102 in any other desired pattern without deviating from the scope of
the present invention.
The lateral plate holes 126 are preferably 2.4 mm. or 2.6 mm. in diameter.
Each of the lateral plate
holes 126 extends through the lateral extension 102 from the proximal face 108
to the distal face 110
along a hole axis angled with respect to a perpendicular to the distal face
110 so that a bone screw 30
inserted therein passes into the bone 10 along a desired line. Specifically,
angles of the lateral plate
holes 126 of this embodiment are selected so that bone screws 30 inserted
therethrough diverge away
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Attorney Docket No. 10139/19902
from the longitudinal axis of the bone plate 100. The lateral plate holes 126
may comprise threads
configured to lockingly engage threading formed on the heads of the bone
screws 30, as those skilled in
the art will understand. Furthermore, angles of the lateral plate holes 126
may be selected to ensure
ample screw purchase in the bone 10 while increasing a pull-out strength
thereof, wherein any angles
may be employed that permit the bone screw to extend through the bone 10
without extending out of an
opposing face of the bone 10.
100091 The shaft 104 terminates at a tapered distal tip 130 which facilitates
percutaneous insertion of
the bone plate 100 minimizing irritation of soft tissue between the incision
and the target location on the
bone. In an exemplary embodiment of the present invention, the bone plate 100
may be used for
fractures of the lateral clavicle, malunions of the lateral clavicle and non-
unions of the lateral clavicle.
The length of the bone plate 100 may be adjusted when treating a clavicle with
a shaft fracture, as those
skilled in the art will understand.
[00010] In accordance with an exemplary method according to the present
invention, a minimally
invasive incision approximately 1 -2 cm. in length is formed over a medial
sternal end of the fractured
clavicle 10. An assessment is made to determine a required plate length and
required bone screw
positions as would be understood by those skilled in the art. Due to
variations in anatomy, the bone
plate 100 may require bending to seat on the clavicle 10 in a desired manner.
To facilitate this bending,
bending irons (not shown) may be used to contour the bone plate 100 as needed
at one or more of the
cutouts 124. It is noted that the bending irons (not shown) may be used to
form a twist at any location
along the length of a bone plate 100'. In one embodiment, as shown in Fig. 6,
the shaft 104 may be
provided with a twist 105 so that a plane housing a distal portion 105' of the
shaft 104 is offset from a
plane housing a proximal portion 105", an offset of the two planes being
selected to permit the bone
plate 100' to be seated over a target portion of bone.
[00011] In one embodiment of the invention, a locking compression plate
("LCP") drill sleeve (not
shown) may be inserted into at least one of the plate holes 106 and/or lateral
plate holes 126 to prevent
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Attorney Docket No. 10139/19902
damage to threads thereof during bending, as those skilled in the art will
understand. After the bone
plate 100 has been contoured, the positions of bone screws 20, 30 inserted
through the plate hole 106
and lateral plate holes 126 may be checked under image intensification to pre-
operatively plan the
fixation of the bone 10. The bone plate 100 is then inserted into the
incision, for example, using the
LCP drill sleeve as a handle. The bone plate 100 is positioned over the
clavicle 10 in a desired position
and fragments 14 are brought into a desired alignment with one another. An
image intensifier known in
the art may be used to ensure proper bone alignment, as those skilled in the
art will understand.
[00012] A physician or other user then determines the type of bone screws 20,
30 to be used in the
bone plate 100, the selection being dependent on the anatomy of the bone 10
and the location of the
fracture 12. In one embodiment, Kirschner wires may be inserted through the
plate holes 106 and
lateral plate holes 126 prior to the insertion of bone screws 20, 30 to verify
the final intended screw
positions. The Kirschner wires then removed prior to insertion of the bone
screws 20, 30. As shown
in Figs. 4 - 5, a universal drill guide 40 may then be used to guide the
insertion of the bone screw 20,
30 into the respective plate holes 106 and lateral plate holes 126. The drill
guide 40 is formed as an
elongated cylindrical shaft 42 with a reduced diameter tip 44 at a distal end
thereof spring loaded to
retract into the shaft 42 upon application of a predetermined pressure. In an
exemplary embodiment,
the drill guide 40 may be used to pre-drill 2.5 mm. holes at desired angles
into the bone 10 at the
desired locations. For insertion of locking screws in the lateral plate holes
126, the drill guide 40 is
inserted through the lateral plate hole 126 and seated against the bone so
that the tip 44 is retracted into
the shaft 42. A drill bit (not shown) is then inserted through the drill guide
40 to drill a bore into the
bone 10 to a desired depth, avoiding contact between the drill bit and the
subclavian artery and brachial
plexus, as those skilled in the art will understand. The drill guide 40 may be
provided with a scale to
determine a required length of the bone screw 30. This ensures that the
selected bone screw 30 does
not go entirely through the bone 10 and damage blood vessels and soft tissue
inferior to the clavicle.
The bone screws 30 which, in a preferred embodiment are 2.7 or 2.4 mm. screws,
are then screwed
into the lateral plate holes 126 either manually or using a powered insertion.
It is noted that although a
universal drill guide 40 is shown, any other drill guide known in the art may
be employed with the
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Attorney Docket No. 10139/19902
exemplary system and method of the present invention, including, but not
limited to, a threaded 3.5 mm
locking hole drill guide, as those skilled in the art will understand.
[00013] Once all the required bone screws 30 have been inserted into the
lateral extension 102, bone
screws 20 may be inserted into the plate holes 106 in substantially the same
manner as described
above. Depending on the requirements of the procedure being performed (e.g.,
based on a fracture
pattern), the bone screw 30 may be inserted into the lateral extension 102
either prior to or after the
insertion of the bone screws 20 into the plate holes 106. If a neutral
position of the bone screw 20 is
desired in the plate hole 106, the drill guide 40 may be pressed into first
hole 112 so that the tip 44 is
retracted into the shaft 42. A bore (not shown) formed by the drill 40 is
spaced from outer walls of the
plate hole 106 due to the increased diameter of the shaft 42 relative to the
tip 44 so that the bone screw
20 is properly guided into the bore without compressing the bone plate 100
during insertion. If a
compression position of the bone screw 20 is desired, the drill guide 40 is
positioned so that the tip 44
is not compressed into the shaft 42 (i.e., with the tip 44 seated contacting a
wall of the first hole 112) so
that the bone screw 20 inserted through this bore contacts walls of the first
hole 112. In this manner, an
eccentrically pre-drilled bore guides an bone screw 20 into the bone at an
angle such that the fracture
and bone plate 100 are compressed. After the target bores have been drilled
into the bone 10, a depth
gauge (not shown) may be inserted through the drill guide 40 to determine a
required bone screw
length, as those skilled in the art will understand. The 3.5 mm bone screws 20
are then inserted into the
bone 10. If locking screws are to be inserted into the second hole 114 of the
plate hole 106, the same
procedure described above is followed with a threaded drill guide being
threaded into the second hole
114 while pre-drilling a bore into the bone and the head of each bone screw 20
being threadedly
screwed into the corresponding second hole 114 until the head is seated flush
against the tapered
portion 120.
[00014] To remove the bone screws 20, 30 and the bone plate 100 from the bone
10 (e.g., after the
bone 10 has healed), each of the bone screws 20, 30 is first unscrewed from
the bone 10 a
predetermined distance so that removal of the bone screws 20, 30 does not
cause a rotation of the
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Attorney Docket No. 10139/19902
bone plate 100 over the bone which may damage adjacent soft tissue. Once
unlocked from the bone
10, the bone screws 20, 30 are individually removed from the body and the bone
plate 100 is then
removed through a minimally invasive incision. It is further noted that the
exemplary method of the
present invention may be used with any other bone plate for insertion into a
living body, including, but
not limited to substantially planar bone plates including LCP plates and
reconstruction plates, as those
skilled in the art will understand.
[00015] As shown in Fig. 7, a bone plate 200 according to an alternate
embodiment of the invention
is formed substantially similarly to the bone plate 100 of Fig. 1 except that
an elongated body 202
thereof includes no lateral extensions 102. The bone plate 200 comprises plate
holes 206 formed
substantially similarly to the plate holes 106 and a plurality of arc-shaped
cutouts 224 substantially
similar to the cutouts 124. The body 202 of the bone plate 200 is provided
with contouring and
curvatures selected to conform to one of a right clavicle and a left clavicle
in the same manner described
above for the plate 100. Furthermore, the bone plate 200 may be further
contoured by a physician to
conform to the anatomy of a particular patient as described earlier.
Furthermore, the bone plate 200
may be configured for one of lateral superior placement over the clavicle or
for medial anterior
placement thereover. Ends of the bone plate 200 may be provided with tapered
tips 230 facilitating
insertion thereof into the body with a minimal amount of tissue irritation
irrespective of which end is
introduced into the body first. The bone plate 200 may be inserted into the
body and locked onto the
clavicle in the same manner described above with respect to the bone plate
100.
[00016] As shown in Fig. 8, a bone plate 300 according to another embodiment
of the invention is
configured for the fixation of acromioclavicular ("AC") joint dislocation and
fractures of the left clavicle.
It is noted however that the bone plate 300 may also be configured for the
fixation of the right clavicle
by mirroring the positions of the components described hereinafter.
Specifically, the bone plate 300
comprises a shaft 302 including an increased diameter lateral extension 304 at
a first end thereof. The
shaft 302 is configured to rest on a shaft of the clavicle 10 while the
lateral extension 304 rests laterally
thereof, closer to the AC joint. The bone plate 300 also comprises a hook 306
with a first portion 308
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CA 02691279 2016-07-15
extending inferior to the lateral extension 304 and a second portion 310
extending laterally
toward the acromion 12 of the scapula 14, as those skilled in the art will
understand. The
shaft 302 and lateral extension 304 further comprise a plurality of plate
holes 312 which
may be a combination of combination plate holes and circular plate holes
extending from a
proximal face of the bone plate 300 to a distal face thereof at any angle
suited to the
requirements of a target bone fixation procedure distributed and oriented in
the same
manner described above.
[00017] Although the present invention has been described with reference to
preferred embodiments, it is submitted that various modifications can be made
to the
exemplary system and method. Accordingly, the foregoing description is by way
of
example only and is not intended to be limiting. Also, the scope of the claims
should not be
limited by those embodiments, but should be given the broadest interpretation
consistent
with the description as a whole.
=
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