Note: Descriptions are shown in the official language in which they were submitted.
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A FRACTURE FIXATION DEVICE AND IMPLANTATION JIG THEREFOR
BACKGROUND OF THE INVENTION
L. Field of the Invention
This invention relates broadly to surgical devices. More particularly, this
invention
relates to surgical devices and tools for implanting fracture fixation
devices.
2. State of the Art
Severe long bone fractures are often treated with plating. In plating, a
relatively large
incision is made at the location of the fracture, musculature and tendons are
displaced from the
bone to expose the bone surface, and a bone plate is fixedly attached to one
or more pieces of
the fractu'red bone in a manner which, ideally, supports and stabilizes the
fracture for healing.
Due to the relatively invasive nature of the procedure required to implant the
plate, plating is
generally reserved for fractures which cannot be treated with a less invasive
method of
immobilization.
Less complicated fractures are often treated with casting or wires. However,
such
conservative treatment may not provide the stabilization and support necessary
for desirable
recovery. Yet, the operative procedure of plating is often too invasive for
the relative non-
severity of the fracture. Moreover, conventional plating can result in tendon
irritation and skin
necrosis, and may require extensive periosteal stripping in order to apply the
plate on the bone
surface. As such, many of the less displaced fractures, and particularly
metaphyseal fractures
(fractures at the end of the long bones), remain under-treated.
By way of example, a Colles' fracture, which results from compressive forces
being
placed on the distal radius bone, and which causes backward displacement of
the distal
fragment and radial deviation of the hand at the wrist, is treated with a
dorsal plate when there
is a significant degree of displacement. However, a less-displaced Colles'
fracture is
commonly under-treated due to the hesitancy of physicians to prescribe
operative and invasive
treatment. If not properly treated, such a fracture results in permanent wrist
deformity. It is
therefore important to align the fracture and fixate the bones relative to
each other so that
proper healing may occur.
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More recently, relatively minimally invasive fixation devices have become
available
for treatment of wrist fractures. For example, U.S. Pat. No. 6,379,359 to
Dahners teaches an
intrafocal fixation device including an intramedullary portion and a plate
portion which seats at
the metaphysis. However, devices like that described in Dahners are not likely
to obtain
acceptance by surgeons or be effective without addressing several critical
issues. First, tha
subchondral bone must be properly supported. Second, the support must be
properly aligned
on the bone. Third, the support for the subchondral bone needs to be applied
in a manner
which is not counter to the minimally invasive design of the implant. Fourth,
the implant
should not necessitate undue removal of bone, which may further weaken the
fracture location.
It is therefore necessary to provide to the surgeon with a fracture fixation
implant and a jig
facilitating the implant thereof.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a fixation device and a
jig for
assistance in implantation of the fixation device relative to a fractured
bone.
It is another object of the invention to provide a fixation device designed to
treat
metaphyseal fractures.
It is a further object of the invention to provide a jig assembly which
provides proper
alignment between longitudinally displaced holes drilled in bone and
corresponding openings
in an intramedullary portion of the fixation, device such that fasteners can
be inserted through
the holes and openings.
It is an additional object of the invention to provide a jig assembly which
facilitates
drilling of axially aligned holes through peg holes in a plate of a fixation
device and through
metaphyseal bone.
In accord with these objects, which will be discussed in detail below, a
fracture fixation
device and a jig therefor are provided.
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A fracture fixation device according to the invention a supra-metaphyseal
plate portion
and an intramedullary nail portion which is horizontally and vertically offset
relative to the
plate portion by a neck portion. The plate portion includes longitudinally
displaced fixed angle
holes, each of which is adapted to orient a peg (or locking screw,
collectively referred to as
`peg') in a different angular orientation such that pegs therethrough
generally corresponds to
the articular surface of the subchondral bone. The nail portion includes
threaded screw holes
oriented normal to an endosteal surface, and a smaller K-wire aligmnent hole
parallel to the
screw holes.
An implantation jig for the fixation device has a first portion with a concave
surface
seatable on the plate portion of the fixation device, and a relatively
elevated second portion in
aligmnent over the screw holes of the intramedullary nail portion of the
fixation device.
The first portion includes openings in alignment with the fixed angle holes. A
cannulated locking drill guide locks the jig relative to the implant and is
used to guide a drill in
alignment with one of the fixed angle holes. The back of the first portion of
the jig is curved
upward to facilitate maneuvering the nail portion of the fixation device
within the intrafocal
space and to allow the first portion to rest on the diaphyseal-side of the
fracture during the
implantation process. The first portion of the jig includes two K-wire guide
holes which
extend on either side of the front end of plate portion when the jig is
coupled to the plate
portion. The K-wire guide holes are designed to closely hold an appropriately
sized K-wire
and direct it at a fixed angle parallel to the endmost screw hole of the plate
portion. Two such
guide holes are provided, as the endmost holes for left and right fixation
devices (for left and
right hands) each have opposite respective angles, and the jig may be used
with each of the left
and right devices. For a particular application, the K-wire guide hole located
on the side of the
operative limb (left or right hand) is used. The respective K-wire guide hole
defines an axis
which is substantially parallel to and closely spaced to the axis of the
endmost screw hole, thus
anticipating the path of a peg through the endmost screw hole. In use, prior
to drilling any
holes into bone for the pegs for the screw holes, a K-wire is drilled into
bone through the
appropriate K-wire guide hole and its placement within the bone is viewed
under fluoroscopy
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to ensure its placement, and the subsequent placement of the peg through the
endmost screw
hole, relative to the articular surface of the subchondral bone is
appropriate.
The second portion of the jig includes longitudinally displaced holes or slots
for drill
guides. The second portion also includes a K-wire guide hole configured to
direct a K-wire at
a fixed angle into the K-wire alignment hole of the nail portion of the
fixation device. Similar
to above, prior to drilling any holes into the diaphysis for the screws for
the nail portion, a K-
wire is drilled through the K-wire guide hole in the second portion and its
placement can be
viewed under fluoroscopy to ensure its placement relative to the diaphysis is
appropriate.
Additional objects and advantages of the invention will become apparent to
those
skilled in the art upon reference to the detailed description taken in
conjunction with the
provided figures.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevation of a fixation device according to the invention;
Fig. 2 is a plan view of a fixation device according to the invention;
Fig. 3 is a bottom view of the plate-portion end of the fixation device of the
invention;
Fig. 4 is a plate-portion end view of the fixation device of the invention;
and
Fig. 5 is a perspective view of an implantation jig according to the invention
coupled to
the fixation device of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning now to Figs. 1 through 4, a fracture fixation device 10 according to
the
invention includes a supra-metaphyseal plate portion 12 and an intramedullary
nail portion 14
which is horizontally and vertically offset relative to the plate portion by a
neck portion 16.
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The plate portion 12 has a narrow profile and is slightly rounded about its
upper surface 20.
The plate portion 12 includes four longitudinally displaced fixed angle holes
22, 24, 26, 28,
each preferably threaded, and each of which is adapted to lock a fastener,
such as a smooth or
threaded shaft peg 30, in a different orientation from the others (i.e., the
axes are oblique
relative to each other). When viewed from the plate end of the device, the
pegs 30 are laterally
displaced defining an imaginary surface (generally transverse to the
longitudinal axis A of the
plate portion) which generally corresponds to (i.e., extends parallel to) the
articular surface of
the subchondral bone. The plate portion 12 includes a dimple 32 for
referencing an
implantation jig, as described below. The nail portion 14 includes three
threaded screw holes
34, 36, 38 oriented normal to a preferably flattened endosteal surface 40, and
a smaller K-wire
alignment hole 42 parallel to the screw holes and sized to closely receive a K-
wire at a fixed
angle. The tail end 44 of the nail portion 14 is provided with a portion 46
having downward
and then upward curve which facilitates maneuvering the tail end of the nail
portion through
the intrafocal space and into the medullary canal.
' With the fixation device 10 in mind, turning now to Fig.5, an implantation
jig 100 for
the fixation device has a first portion 102 seatable on the plate portion 12
of the fixation
device, and a relatively elevated second portion 104 in alignment over the
screw holes 34, 36,
38 of the intramedullary nail portion 14 of the fixation device 10.
The first portion 102 includes a lower nub (not shown) which seats in the
dimple 32
(Fig. 2) on the plate portion 12 of the fixation device. In addition, the
first portion includes
access openings 106 (at the front), 110 (at the left side, and at right the
side, not shown), 108
(at the rear) in axial alignment with the fixed angle screw holes 22, 24, 26,
28. Such openings
are preferably initially positioned over drill guide tips (not shown) which
are inserted in all of
the fixed angle holes of the plate portion but the hole beneath access opening
110. The drill
guide tips which functions as miniature drill guides, are described in detail
in co-owned U.S.
Serial No. 11/011,917, filed December 14, 2004, which is hereby incorporated
by reference
herein in its entirety. As another option, the drill guides tips are not
necessitated, and
individual drill guides can be inserted into the fixed angle holes just prior
to drilling holes into
bone in alignment with the holes.
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In accord with one aspect of the invention, a cannulated locking drill guide
116 having
a threaded end 118 is provided through opening 110 and thread into hole 26 in
the plate
portion 12, such that a portion of the guide 116 applies a force against said
jig 100. The
locking drill guide 116 in conjunction with the engagement of the nub within
the dimple 32
immobilizes the jig 100 relative to the fixation device 10 so that the two are
fixed relative to
each other.
In accord with another aspect of the invention, the back 120 of the first
portion 102 of
the jig 100 is curved upward to facilitate maneuvering the nail portion 14 of
the fixation device
within the intrafocal space and to allow the first portion to rest on the
diaphyseal-side of the
fracture (e.g., the proximal cortex of the distal radius) during the
implantation process.
The plate portion 12 of the fixation device 10 is too narrow to support the
inclusion of
K-wire guide holes. Thus, in accord with a further aspect of the invention,
the first portion 102
of the jig 100 includes two K-wire guide holes 122, 124 which extend on either
side of the
front of the plate portion when the jig 100 is fixed relative to the fixation
deice 10 to guide a
K-wire offset relative to the plate portion. The K-wire guide holes 122, 124
are designed to
closely hold an appropriately sized K-wire 126 and direct it at a fixed angle
parallel to the
endmost screw hole 22 (e.g., distalmost where the fixation device is used at
the distal radius).
Two such guide holes are provided, as the endmost holes for left and right
fixation devices (for
left and right hands) each have opposite respective angles, and the same jig
may be used with
each of the left and right devices. For a particular application, the K-wire
guide hole located
opposite the side on which the locking drill guide is positioned is used. That
is, as shown in
Fig. 5, with the locking drill guide on the left side of the plate, the right
side K-wire guide hole
122 is used. The respective K-wire guide hole 122 defines an axis which is
laterally offset,
substantially parallel to, and closely spaced to the axis of the endinost
screw hole 22
(preferably within approximately 5 mm), thus anticipating the path of a peg
through the
endmost screw hole 22. In use, prior to drilling any holes into bone for the
pegs 30 for the
screw holes, a K-wire 126 is drilled into bone through the appropriate K-wire
guide hole 122
and its placement within the bone is viewed under fluoroscopy to ensure its
placement relative
to the articular surface of the subchondral bone is appropriate. If correct,
the screw holes can
be drilled with assurance that the screws will not enter the articular space.
If not correctly
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located as indicated by K-wire fluoroscopic visualization, the plate can be
repositioned, the K-
wire re-drilled and re-examined until placement is correct.
The second portion 104 of the jig includes longitudinally displaced holes or
slots 130,
132, 134, as described in detail in U.S. Pat. No. 6,926,720, to longitudinally
align drill guides
with the screw holes 34, 36, 38 of the intramedullary portion 14 of the
fixation device 10. In
accord with yet another aspect of the invention, the second portion 104 also
includes a K-wire
guide hole 136 configured to direct a K-wire 138 at a fixed angle into the K-
wire alignment
hole 142 of the nail portion of the fixation device. Similar to above, prior
to drilling any holes
into the diaphysis for the screws for the nail portion, a K-wire is drilled
through the K-wire
guide hole in the second portion and its placement can be viewed under
fluoroscopy to ensure
its placement relative to the diaphysis is appropriate. If correct, the screw
holes can be drilled
with assurance that the screws will be properly aligned relative to the axis
of the diaphysis. If
not correctly aligned as indicated by fluoroscopic visualization, the nail
portion can be
repositioned, the K-wire re-drilled and re-examined until placement is
correct.
The jig is usable in combination with drill guides, bits and gauges as
described in
previously incorporated U.S. Patent No. 6,926,720.
There have been described and illustrated herein embodiments of a fixation
device and
implantation jig therefor. While particular embodiments of the invention have
been described,
it is not intended that the invention be limited thereto, as it is intended
that the invention be as
broad in scope as the art will allow and that the specification be read
likewise. For example,
while pegs have been described for use within the fixation device, other fixed
angle bone
fixators can be used as well. It will therefore be appreciated by those
skilled in the art that
modifications could be made to the provided invention without deviating from
its spirit and
scope as claimed.
