U.S. patent application number 13/023228 was filed with the patent office on 2012-08-09 for low profile dorsal plate.
Invention is credited to Christopher Harris Martin.
Application Number | 20120203227 13/023228 |
Document ID | / |
Family ID | 46601148 |
Filed Date | 2012-08-09 |
United States Patent
Application |
20120203227 |
Kind Code |
A1 |
Martin; Christopher Harris |
August 9, 2012 |
LOW PROFILE DORSAL PLATE
Abstract
A low profile dorsal plate for internal fixation of a radius
fracture can comprise a single longitudinal portion having a distal
end, and a transverse portion fixed across the distal end at an
angle of about 15.degree. to about 30.degree. from perpendicular
with respect to the longitudinal portion. The transverse portion
can also have a z-axis curvature, or can be flexible to form a
z-axis curvature, where the z-axis curvature corresponds to a
dorsal contour of a distal radius. Also included is a first
plurality of screw holes aligned within the longitudinal portion
and a second plurality of screw holes aligned within the transverse
portion.
Inventors: |
Martin; Christopher Harris;
(Salt Lake City, UT) |
Family ID: |
46601148 |
Appl. No.: |
13/023228 |
Filed: |
February 8, 2011 |
Current U.S.
Class: |
606/70 ;
606/286 |
Current CPC
Class: |
A61B 17/8085 20130101;
A61B 17/8061 20130101 |
Class at
Publication: |
606/70 ;
606/286 |
International
Class: |
A61B 17/80 20060101
A61B017/80 |
Claims
1. A low profile dorsal plate for internal fixation of a radius
fracture, comprising: a single longitudinal portion having a distal
end; a transverse portion fixed across the distal end at an angle
of about 15.degree. to about 30.degree. from perpendicular with
respect to the longitudinal portion, and having a z-axis curvature
or being flexible to form a z-axis curvature, where said z-axis
curvature corresponds to a dorsal contour of a distal radius; a
first plurality of screw holes positioned along the longitudinal
portion; and a second plurality of screw holes positioned along the
transverse portion.
2. The low profile dorsal plate of claim 1, wherein the transverse
portion is sufficiently flexible so that the z-axis curvature is
adjustable after initial attachment of the dorsal plate to the
radius.
3. The low profile dorsal plate of claim 1, wherein the distal end
is configured for adjustment of the angle between the longitudinal
section and the transverse section.
4. The low profile dorsal plate of claim 1, wherein the plate
includes a metal selected from iron, titanium, chromium, cobalt,
molybdenum, nickel, and alloys thereof.
5. The low profile dorsal plate of claim 1, wherein the plate
includes an alloy selected from stainless steel, cobalt chromium,
and alloyed titanium.
6. The low profile dorsal plate of claim 1, wherein the
longitudinal portion has a flat cross-section.
7. The low profile dorsal plate of claim 1, wherein the
longitudinal portion has a curved cross-section.
8. The low profile dorsal plate of claim 1, wherein the transverse
portion has a maximum width of less than about 1 cm.
9. The low profile dorsal plate of claim 1, wherein the
longitudinal portion has a maximum width of less than about 1.25
cm.
10. The low profile dorsal plate of claim 1, wherein at least one
of the screw holes has a countersink configuration.
11. The low profile dorsal plate of claim 1, wherein at least one
of the screw holes is configured to accommodate multiple angles of
insertion of a screw into the distal extremity.
12. The low profile dorsal plate of claim 1, wherein at least one
of the screw holes exhibits a non-circular shape.
13. The low profile dorsal plate of claim 1, wherein at least one
of the screw holes is elongated in shape.
14. The low profile dorsal plate of claim 1, wherein the transverse
portion includes an x-y curvature.
15. The low profile dorsal plate of claim 14, wherein at least a
portion of the x-y curvature extends away from the longitudinal
portion.
16. The low profile dorsal plate of claim 1, wherein the transverse
portion is linear.
17. The low profile dorsal plate of claim 1, wherein the first
plurality of screw holes are aligned along the longitudinal
portion.
18. The low profile dorsal plate of claim 1, wherein the second
plurality of screw holes are aligned along the transverse
portion.
19. The low profile dorsal plate of claim 1, wherein the second
plurality of screw holes are not all aligned along the transverse
portion.
20. The low profile dorsal plate of claim 1, wherein the angle is
from about 18.degree. to about 26.degree..
21. A method for fixation of a distal radial fracture, comprising:
partially dissecting a retinaculum of a wrist exhibiting a
fractured distal radius to create a flap; retracting tendons and
the flap overlying the fractured distal radius; attaching a dorsal
plate to a distal extremity of the fractured distal radius, wherein
the dorsal plate comprises: a single longitudinal portion having a
distal end; a transverse portion fixed across the distal end at an
angle of about 15.degree. to about 30.degree. from perpendicular
with respect to the longitudinal portion, and having a z-axis
curvature or being flexible to form a z-axis curvature, where said
z-axis curvature corresponds to a dorsal contour of a distal
radius; a first plurality of screw holes positioned along the
longitudinal portion; and a second plurality of screw holes
positioned along the transverse portion; and securing the flap to
cover the transverse portion; wherein the transverse portion is at
least partially covered by the retinaculum so that there is
substantially no direct contact between the tendons and the
transverse portion.
22. The method of claim 21, wherein the flap has a width of no
greater than about 1 cm.
23. The method of claim 21, wherein the transverse portion further
includes an x-y curvature, at least a portion of the x-y curvature
extending away from the longitudinal portion.
24. A system for dorsal fixation of a radius fracture, comprising a
low profile dorsal plate, wherein the dorsal plate comprises: a
single longitudinal portion having a distal end; a transverse
portion fixed across the distal end at an angle of about 15.degree.
to about 30.degree. from perpendicular with respect to the
longitudinal portion, and having a z-axis curvature or being
flexible to form a z-axis curvature, where said z-axis curvature
corresponds to a dorsal contour of a distal radius; a first
plurality of screw holes positioned along the longitudinal portion;
and a second plurality of screw holes positioned along the
transverse portion; and a screw configured for insertion into bone
and dimensioned to fit in at least one of the screw holes.
25. The system of claim 24, wherein the screw is one of a
self-tapping screw, self-locking screw, cannulated screw, cortical
bone screw, or cancellous bone screw.
26. The system of claim 24, wherein the transverse portion has a
maximum width of about 1 cm.
27. The system of claim 24, wherein the longitudinal portion has a
maximum width of about 1.25 cm.
28. The system of claim 24, wherein the transverse portion further
includes an x-y curvature, at least a portion of the x-y curvature
extending away from the longitudinal portion.
29. The system of claim 24, wherein the angle is from about
18.degree. to about 26.degree.
Description
BACKGROUND
[0001] Distal radius fractures are a common type of bone fracture
of the radius of the forearm. The treatment of fractures of the
distal radius has involved surgical and non-surgical means, such as
casting. In the case of fractures involving many fragments of bone,
treatment becomes progressively more difficult and casting, or
non-surgical treatment, is generally less satisfactory. This is
especially true when the articular surface, or joint surface, is
fractured into multiple fragments. Such fractures, involving
numerous fragments, are generally longitudinally unstable and have
been treated with various devices to regain longitudinal stability.
External fixation has provided longitudinal stability, but does not
offer fixation means for multiple articular fragments. Furthermore,
external fixation increases the risk of infection, since the pins
screwed into the bone communicate with the outside and are thus
contaminated. External fixation also frequently results in
considerable wrist stiffness due to traction effects on the
ligaments of the wrist.
[0002] Internal plate fixation with locking screws, in which the
screws may be secured to the plate, offer an internal means of
achieving longitudinal stability, thereby avoiding infection risks
compared with external fixation. Internal plate fixation also
allows for manipulation of multiple articular fragments and offers
the potential to secure and longitudinally stabilize these
fragments while not crossing the wrist joint itself, thereby
facilitating rehabilitation and potentially minimizing the risks of
wrist stiffness.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] FIG. 1A is a top view diagram of a dorsal plate according to
an example of the present disclosure;
[0004] FIG. 1B is a top view diagram of the transverse portion of a
dorsal plate according to another example of the present
disclosure;
[0005] FIG. 1C is a top view diagram of the transverse portion of a
dorsal plate according to still another example of the present
disclosure;
[0006] FIG. 2A is a cross-sectional diagram of the longitudinal
portion of a dorsal plate according to an example of the present
disclosure;
[0007] FIG. 2B is a cross-section diagram of the longitudinal
portion of a dorsal plate according to another example of the
present disclosure; and
[0008] FIG. 3 is a cross-section diagram of a distal radius to
which is attached a transverse portion of a dorsal plate according
to an example of the present disclosure.
DETAILED DESCRIPTION
[0009] Reference will now be made to the examples illustrated, and
specific language will be used herein to describe the same.
Features and advantages of the technology will be apparent from the
detailed description which follows, taken in conjunction with the
accompanying drawings, which together illustrate, by way of
example, features of the technology.
[0010] It is to be noted that, as used in this specification and
the appended claims, the singular forms "a," "an," and "the"
include plural referents unless the context clearly dictates
otherwise.
[0011] Coordinate axes (e.g. "x", "y", and "z") are used herein to
describe dimensional aspects of devices. For example, where
longitudinal and transverse aspects of a device lie in a plane
defined by x and y axes (i.e. the x-y plane), aspects that are
perpendicular to this plane are considered to lie along the z-axis.
Anatomical terms (e.g. "dorsal", "volar", "proximal", "distal") are
used to describe axes, planes, directions relative to the body of a
subject.
[0012] When referring to a "curve" or a "curvature," the context of
that discussion will dictate which curvature is being discussed.
For example, in some embodiments herein, the transverse portion
will be described with respect to a curvature in an x-y plane (x-y
curvature). Examples of this type of curvature are shown in FIGS.
1A and 1B. However, the transverse portion can also be curved, or
be flexible or malleable enough for a surgeon to form a z-axis
curvature (i.e. in a plane essentially perpendicular to the x-y
axis) that corresponds to a dorsal contour of a distal radius.
[0013] When referring to a relative "angle" from perpendicular as
it relates to the transverse portion fixed across the distal end of
the longitudinal portion, the angle is measured from 90.degree.
where the transverse portion crosses the longitudinal portion. If
the transverse portion is curved as shown in FIGS. 1A and 1B, then
the tangent of the curve at the point of intersection is what is
used to determine the angle from perpendicular.
[0014] Use of the term "flexibility" to describe portions of the
dorsal plate herein means that the portion is manually bendable at
room temperature by a human operator without requiring the
assistance of powered tools.
[0015] As used herein, the term "about" is used to provide
flexibility to a numerical range endpoint by providing that a given
value may be "a little above" or "a little below" the endpoint. The
degree of flexibility of this term can be dictated by the
particular variable and would be within the knowledge of those
skilled in the art to determine based on experience and the
description herein.
[0016] As used herein, the term "substantially" refers to the
complete or nearly complete extent or degree of an action,
characteristic, property, state, structure, item, or result. The
exact allowable degree of deviation from absolute completeness may
in some cases depend on the specific context. However, generally
speaking the nearness of completion will be so as to have the same
overall result as if absolute and total completion were obtained.
The use of "substantially" is equally applicable when used in a
negative connotation to refer to the complete or near complete lack
of an action, characteristic, property, state, structure, item, or
result.
[0017] Sizes, amounts, and other numerical data may be expressed or
presented herein in a range format. It is to be understood that
such a range format is used merely for convenience and brevity and
thus should be interpreted flexibly to include not only the
numerical values explicitly recited as the limits of the range, but
also to include all the individual numerical values or sub-ranges
encompassed within that range as if each numerical value and
sub-range is explicitly recited. As an illustration, a numerical
range of "about 0.01 to 2.0 cm" should be interpreted to include
not only the explicitly recited values of about 0.01 cm to about
2.0 cm, but also include individual values and sub-ranges within
the indicated range. Thus, included in this numerical range are
individual values such as 0.5, 0.7, and 1.5, and sub-ranges such as
from 0.5 to 1.7, 0.7 to 1.5, and from 1.0 to 1.5, etc. This same
principle applies to ranges reciting only one numerical value.
Furthermore, such an interpretation should apply regardless of the
breadth of the range or the characteristics being described.
[0018] As used herein, a plurality of items, structural elements,
compositional elements, and/or materials may be presented in a
common list for convenience. However, these lists should be
construed as though each member of the list is individually
identified as a separate and unique member. Thus, no individual
member of such list should be construed as a de facto equivalent of
any other member of the same list solely based on their
presentation in a common group without indications to the
contrary.
[0019] The present disclosure is directed to devices and methods
for fixation of distal radial fractures. As used herein, the term
"subject" refers particularly to a primate (e.g. a human), as well
as to vertebrates having a wrist with skeletal structure and
associated musculature in an arrangement similar to that seen in
the wrist of primates.
[0020] Internal plate fixation can be accomplished with a plate
designed for either the volar surface or the dorsal surface of the
distal radius. The majority of fractures of the distal radius
requiring operative treatment involve significant dorsal
fragmentation and shortening of the bone. A dorsal surgical
approach to the distal radius thereby affords direct access to the
area of most damage to the bone in the majority of cases. A dorsal
surgical approach also affords direct access to the articular or
joint surface of the distal radius.
[0021] Prior dorsal plate designs, however, resulted in frequent
complications, especially due to irritation and rupture of the
extensor tendons at the wrist. As these complications became
evident in clinical experience, practice shifted to fixation of
dorsally displaced fractures using plates applied to the volar
surface of the distal radius, allegedly avoiding the complications
pertaining to the extensor tendons. The use of dorsal plates became
less common.
[0022] However, certain difficulties are attendant on the use of
volar plates. For example, access to the distal radius articular
surface can be considerably more difficult to achieve from a volar
surgical approach, due in part to the presence of the critical
wrist (or radiocarpal) ligaments being present on the volar side of
the wrist. Furthermore, due to the presence of dorsal damage,
proper fixation involves driving fixing screws sufficiently far
through the radius to engage the dorsal region, often penetrating
the dorsal surface. Consequently, there have continued to be
difficulties with extensor tendons caused by screws penetrating the
dorsal aspect the distal radius and rubbing tendons directly.
Furthermore, volar plates have typically been designed to be
substantial enough to counteract the large bending moments on these
plates (these bending forces are very minimal on dorsal plates),
and therefore these plates are relatively thick. The thickness of
these plates has resulted in attritional ruptures of the flexor
tendons (especially to the thumb) due to friction of the flexor
tendon on the plate.
[0023] Perhaps the most common difficulty is in obtaining
congruence of the articular or joint surface of the distal radius
due to limitations of the volar surgical approach, in which the
volar ligaments should not be violated and direct visualization of
the joint is therefore very difficult. Due to this difficulty with
the volar surgical approach, surgeons have utilized greatly
extended approaches to inspect the joint surface through the dorsal
side of the wrist, or simply made a second exposure through the
dorsal side of the wrist. To avoid further surgical dissection and
morbidity, indirect visualization of the articular surface with
fluoroscopic x-ray machines has been utilized. However, there are
significant limitations in the resolution and accuracy of these
machines in determining the congruence of the articular surface of
the distal radius. In fact, there have been difficulties with
screws placed from the volar side into the wrist joint due to an
inability to see directly into the joint.
[0024] The present technology includes devices, systems, and
methods for direct dorsal fixation that address some of the
negative issues found with prior approaches. In accordance with
this, a low profile dorsal plate for internal fixation of a radius
fracture can comprise a single longitudinal portion having a distal
end, and a transverse portion fixed across the distal end at an
angle of about 15.degree. to about 30.degree. from perpendicular
with respect to the longitudinal portion. The transverse portion
can be linear in the x-y plane or have a curvature in the x-y
plane. The transverse portion can also have a z-axis curvature that
corresponds to a dorsal contour of a distal radius, or the
transverse portion can be flexible to form such a curvature. Also
included is a first plurality of screw holes aligned within the
longitudinal portion and a second plurality of screw holes aligned
within the transverse portion. In one specific embodiment, a system
for dorsal fixation of a radius fracture can comprise the low
profile dorsal plate described above, and a screw configured for
insertion into bone and dimensioned to fit in at least one of the
screw holes.
[0025] In another embodiment, a method for fixation of a distal
radial fracture can comprise steps of partially dissecting a
retinaculum of a wrist exhibiting a fractured distal radius to
create a flap, and retracting tendons and the flap overlying the
fractured distal radius. Once retracted, additional steps include
attaching the dorsal plate described above to a distal extremity of
the fractured distal radius, and securing the flap to cover the
transverse portion. Thus, the transverse portion is covered by the
retinaculum so that there is substantially no direct contact
between the tendons and the transverse portion.
[0026] The wrist at the distal radius includes a large number of
tendons connecting the extensor muscles to their points of
insertion in the hand. These tendons are enclosed in a number of
compartments formed by synovial sheaths and overlain by the fibrous
dorsal carpal ligament, or retinaculum. Prior dorsal fixation
devices often interfered with tendon function in this space,
resulting in tendon rupture and other complications. The low
profile plate of the present disclosure is shaped and dimensioned
so as to minimize the space occupied by the plate among the various
extensor compartments in the wrist. In particular, "low profile" as
described herein refers to a relatively thin and narrow
cross-section of the portions of the plate, such that the plate can
reside among the wrist extensors without causing significant
displacement of or friction against any extensors.
[0027] In another aspect, the transverse portion is sufficiently
narrow and thin to cause minimal displacement or friction with
respect to overlying wrist extensors, for example by being able to
be covered by a flap of the retinaculum. Where the transverse
portion and any attaching screws are covered by the retinaculum,
these elements are thereby prevented from rubbing against overlying
tendons. Therefore, complications otherwise associated with dorsal
fixation approaches (i.e. irritation and rupture) can be avoided.
This approach is facilitated by use of a dorsal plate with a narrow
transverse portion, such that a relatively narrow section of the
retinaculum is sufficient for use in covering the transverse
portion. In a specific example, a strip of retinaculum having a
width of around 1 cm can be sufficient to cover the transverse
portion of the dorsal plate, though larger widths can also be
used.
[0028] In each of these embodiments, the dorsal plate can be
constructed of any material that is biocompatible and provides
sufficient strength for fixing fragments in bone. In particular,
metals are suitable for manufacture of dorsal plates, including
iron, titanium, chromium, cobalt, molybdenum, and nickel, to name a
few. In some embodiments, biocompatible alloys of these metals can
be particularly suited for this use, such as stainless steel,
cobalt chromium, and alloyed titanium.
[0029] Turning now to the FIGS., FIG. 1A shows a low profile dorsal
plate 100 in accordance with an example of the present disclosure.
The plate comprises a single longitudinal portion 10 configured for
attachment along the longitudinal axis of the distal radius. In
particular, the single longitudinal portion provides a sufficiently
narrow longitudinal profile so that once attached to the bone, the
longitudinal portion sits readily between adjacent extensor tendon
compartments. In a particular aspect, the longitudinal portion is
sufficiently narrow so as to fit between the tendons of two wrist
extensors or between two tendon compartments when the plate is
attached to the distal extremity of the radius of a subject. In a
specific example, the longitudinal portion of the plate in
accordance with the present disclosure can fit between the extensor
pollicis longus (EPL) and the extensor carpus radialis brevis
(ECRB) of the subject. In another aspect, the narrow profile of the
single longitudinal portion allows for this component to have a
thickness that provides sufficient resistance to bending forces
that occur in the wrist, while still occupying a small
cross-sectional space within the wrist. In an example, the
longitudinal portion has a maximum width of less than about 1.25
cm.
[0030] The longitudinal portion 10 can be configured for secure
attachment to the radius. In one example as shown in FIG. 2A, the
longitudinal portion can have a substantially flat cross-sectional
profile. The narrow width of the longitudinal portion relative to
that of the dorsal surface of the radius can allow secure and
stable attachment of the plate with a flat profile. Alternatively,
the longitudinal portion can exhibit a curved cross-section as
shown in FIG. 2B, where the curvature can be substantially matched
to a curvature of the radial surface for added stability. It is
noted that FIGS. 2A and 2B are not necessarily drawn to scale.
[0031] Referring again to FIG. 1A, the dorsal plate 100 can further
comprise a transverse portion 12 configured for attaching the plate
to the distal extremity of the radius for purposes of fixing and
stabilizing fractures. The transverse portion has dimensions that
contribute to the low profile of the plate. In a particular
example, the transverse portion has a maximum width of less than
about 1 cm. In another aspect, the transverse portion is fixed at
an angle across the distal end of the longitudinal portion 10. The
angle between the transverse portion and longitudinal portion can
be selected to correspond to the shape of the distal extremity of
the radius. In particular, due to the styloid process of the distal
radius, the dorsal aspect of the articular surface typically
exhibits an angle so that the radial aspect of the surface extends
farther distal than the ulnar aspect. The angle between the
transverse portion and longitudinal portion of the plate can
correspond to the angle of the articular surface. Specifically, the
transverse portion can be situated so that the angle is from about
15.degree. to about 30.degree. from perpendicular to the
longitudinal portion. In a more specific example, the angle is from
about 18.degree. to about 26.degree.. In a still more specific
example, this angle can be about 22.degree..
[0032] Depending on the size of the subject's radius or other
factors (e.g. deformity or damage) affecting the shape of the bone,
effective fixation may involve adjusting the angle between the
transverse portion and the longitudinal portion. In one example,
the distal end of the longitudinal portion can be configured at the
junction with the transverse portion for adjustment of the angle.
By way of non-limiting example, this feature can be provided by
selecting a sufficiently flexible material for use at this
location, or by giving the end a dimension that provides sufficient
flexibility. Alternatively, the end can be configured to provide
multiple selectable angles of connection to the transverse
portion.
[0033] The dorsal plate as described herein can be attached to the
radius using any type of fastener that can be applied through a
dorsal surgical exposure, and that provides secure and stable
attachment to bone. Fasteners known in the art for bone fixation
include pins, wire, and screws. In a particular example, a system
for dorsal fixation of a radius fracture can comprise a low profile
dorsal plate as described herein together with at least one screw.
Non-limiting examples of suitable screws include self-tapping
screws, self-locking screws, cannulated screws, cortical bone
screws, cancellous bone screws, and screws having combinations of
features exhibited by these. Accordingly, to accommodate insertion
of screws, the dorsal plate can include a plurality of screw holes.
In a particular aspect, a plurality of screw holes can be
distributed along the length of a component of the plate. More
specifically as shown in FIG. 1A, the longitudinal portion can
include a first plurality of screw holes 14, and the transverse
portion can include a second plurality of screw holes 16.
[0034] The screw holes can be distributed and configured in such a
way that is consistent with the low profile of the plate. In one
aspect, a dorsal plate can include screw holes that are shaped to
accept a screw to a depth so that the screw does not significantly
increase the profile of the installed plate in the wrist. In a
specific example, such a screw hole can include a countersink
configuration. In another aspect, the plurality of screw holes can
be distributed so as to occupy a minimal width. More specifically,
the screw holes can be aligned within the shape of the longitudinal
portion and the transverse portion. As used herein, the term
"aligned" refers to an arrangement in which the centers of the
holes are intersected by a single uninflected line or curve.
Therefore, screw holes that are said to be "aligned" can be
arranged in a single straight or curved line. This is illustrated
in the plate of FIG. 1A, which includes a straight linear
arrangement of the first plurality of screw holes 14 in the
longitudinal portion, and a curved arrangement of the second
plurality of screw holes 16. In an alternative example as shown in
FIG. 1B, one or more of the screw holes may not be aligned, but
rather, can deviate from this arrangement. For example,
displacement of one or more screw holes can aid in placing screws
in denser bone, or in order to place screws a sufficient distance
from the line of a fracture.
[0035] The diameter of the screw holes can be selected to
accommodate available types of bone screws. In a particular
example, the average width of a component of the dorsal plate can
be decreased by further narrowing the component width between two
screw holes. In an alternative example, the component can have
substantially the same width along its length. In such an example,
the width can be selected to accommodate screw holes of a selected
maximum diameter.
[0036] Screw holes included in the plate can include other features
to aid in secure placement. In one example, a screw hole can
include one or more features for securing the screw in place once
inserted, such as threading to capture a threaded screw head. In
another example, a screw hole can be configured to allow for more
than one angle of insertion for a screw. In some cases, additional
features can be realized by selecting the shape of the screw hole.
That is, the screw holes in a dorsal plate can have a circular
shape, or alternatively one or more non-circular shape can be
included. In one example, at least one screw hole has an elongated
shape. One such elongated shape is illustrated by the two distal
screw holes in the plate shown in FIG. 1A. An elongated screw hole
can also allow a greater degree of freedom for selecting a point on
the bone for insertion of a screw. In another example, a
non-circular hole shape (e.g. square or star-shaped) can be used
for insertion of a screw having a similarly shaped head, which can
serve to secure the screw in place once fully inserted.
[0037] The transverse portion 12 can further be shaped or otherwise
configured for effective attachment to the distal extremity of the
radius. The dorsal plates in FIGS. 1A through 1C show examples of
shapes that can be exhibited by transverse portions in accordance
with the present disclosure. The transverse portion can be
substantially linear within the x-y plane as illustrated in FIG.
1C, or alternatively, the transverse portion can have a curvature
in that plane, as shown in FIGS. 1A and 1B. In a particular
example, this curvature can approximate a distal/proximal curvature
exhibited by the dorsal articular surface. In both straight and
curved transverse portion examples, at least a part of the
transverse portion is situated at an angle from perpendicular to
the longitudinal portion 10, as described above. As shown in the
diagram of FIG. 1A, in one aspect, each transverse portion has a
radial branch 18 that forms an obtuse angle 20 with the
longitudinal portion. In another aspect, the transverse portion has
an ulnar branch 22 that forms an acute angle 24 with the
longitudinal portion. In an aspect of these examples, the degree of
angle and/or curvature of either or both branches can be selected
to allow the transverse portion to be positioned for solid
attachment to bone.
[0038] FIG. 3 shows a cross-section of a distal radius with the
transverse portion 12 of a dorsal plate attached thereto. As shown,
the transverse portion 12 can also have a z-axis curvature (e.g.,
in the dorsal/volar axis with respect to the distal radius). In a
particular example, the curvature can correspond to a dorsal/volar
curvature of the articular surface of the distal radius. Curvature
of the transverse portion in this axis can allow the transverse
portion to be closely associated with the surface of the radius
along substantially the whole length of the transverse portion.
This in turn allows attachment screws 26 to be inserted into the
surface of the bone at or near a normal angle.
[0039] In one example, the transverse portion can be configured to
be bendable so as to provide a particular curvature. In some cases,
this may be facilitated by having the plate partially installed so
that the transverse portion can be matched to the curvature of the
subject's radius. Accordingly, in a particular example, the
transverse portion is configured to be bendable or malleable after
part of the plate (e.g. the longitudinal portion) has already been
attached. This flexibility is exhibited along substantially the
entire length of the transverse portion (rather than being
restricted to specific regions), allowing more complete
correspondence between the curvature of the transverse portion and
the contour of the distal radius. In a particular aspect, the
flexibility allows independent positioning of each screw hole
relative to the radius surface. The bendability of the transverse
portion can be a product of the materials chosen for the plate as
well as the thickness of the transverse portion. In another
example, the attachment point between the transverse portion and
the longitudinal portion is configured so that the angle is
adjustable.
[0040] As noted above, a method of fixing a wrist fracture using a
dorsal approach can comprise dissecting and retracting a flap of
the retinaculum prior to attachment of the dorsal plate to the
radius. The extensors and other underlying tissue can also be
retracted to expose the bone for attachment of the plate. Once the
plate has been attached, the flap of retinaculum can be drawn over
the plate so as to cover the transverse portion. With the flap in
place, the tendons can be released to resume their original
orientation, where the flap is now interposed between the tendons
and the plate. In accordance with the example, the flap covers the
transverse portion and prevents direct contact between the
transverse portion and the overlying tendons. In this way the
tendons are protected from friction from the dorsal plate, thereby
reducing rupture or other complications that can arise from such
contact. This approach is facilitated by the narrow profile of the
transverse portion, so that the transverse portion can be partially
or completely covered by the flap of retinaculum. In a further
aspect, the size of the flap dissected from the original
retinaculum can be minimized, reducing the postoperative impact of
the procedure on retinacular function. In a particular example, a
flap of about 1 cm in width can sufficient to completely cover the
transverse portion, though more or less may be used at the
discretion of the surgeon.
[0041] While the forgoing examples are illustrative of the
principles of the present technology in one or more particular
applications, it will be apparent to those of ordinary skill in the
art that numerous modifications in form, usage and details of
implementation can be made without the exercise of inventive
faculty, and without departing from the principles and concepts of
this technology. Accordingly, it is not intended that the
technology be limited, except as by the claims set forth below.
* * * * *