U.S. patent number 3,760,802 [Application Number 05/227,371] was granted by the patent office on 1973-09-25 for supporting device for fractured tubular bones.
This patent grant is currently assigned to SAID Fischer, by said Muller. Invention is credited to Artur Fischer, Jean-Nicolas Muller.
United States Patent |
3,760,802 |
Fischer , et al. |
September 25, 1973 |
SUPPORTING DEVICE FOR FRACTURED TUBULAR BONES
Abstract
An elongated supporting sleeve is to be introduced into a
longitudinally extending curved interior cavity of a fractured
tubular bone. It is curved in at least substantial conformance with
the curvature of the bone cavity and has an internal passage
extending longitudinally and through which an expander rod of
similar curvature extends. At the front end of the supporting
sleeve is located an expansion element which, when the expander rod
is withdrawn in axially rearward direction through the passage of
the supporting sleeve, is expanded into engagement with the inner
walls bounding the bone cavity. An instrumentality is provided for
so withdrawing the expander rod that it will perform only a
rearward axial movement but will not turn.
Inventors: |
Fischer; Artur (Tumlingen,
DT), Muller; Jean-Nicolas (Strassbourg,
FR) |
Assignee: |
SAID Fischer, by said Muller
(Tumlingen, DT)
|
Family
ID: |
46318775 |
Appl.
No.: |
05/227,371 |
Filed: |
February 18, 1972 |
Foreign Application Priority Data
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Feb 26, 1971 [DT] |
|
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P 21 09 162.3 |
Mar 30, 1971 [DT] |
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P 21 15 189.6 |
Apr 23, 1971 [DT] |
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P 21 19 902.0 |
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Current U.S.
Class: |
606/63; 411/55;
411/50 |
Current CPC
Class: |
A61B
17/7225 (20130101); A61B 17/7266 (20130101); A61B
17/7233 (20130101) |
Current International
Class: |
A61B
17/68 (20060101); A61B 17/72 (20060101); A61f
005/04 () |
Field of
Search: |
;128/92BC,92BB,92CA,92B,92D,92R ;85/77,84,76 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Yasko; J.
Claims
What is claimed as new and desired to be protected by Letters
Patent is set forth in the appended claims:
1. A supporting device for fractured tubular bones which have a
longitudinally extending curved interior cavity, comprising an
elongated supporting sleeve having a leading and a trailing end
portion and being curved in at least substantial conformance with
said cavity, said supporting sleeve being provided with a curved
longitudinal passage having a widened section at said trailing end
portion; an expansion element at said leading end portion located
forwardly thereof; expander means associated with said expansion
element, said expander means including rod-shaped means extending
through said passage between said end portions and adapted to
expand said element in response to axial displacement towards said
trailing end portion, and displacing means at least partially
received in said widened section in engagement with said rod-shaped
means and operative for effecting displacement thereof only axially
of said supporting sleeve in direction towards said trailing end
portion, said displacing means being a hollow internally threaded
cap sleeve having an open end facing away from said leading end
portion, and said rod-shaped means having external screw threads
which mesh with the internal threads of said cap sleeve; and a cap
screw having external threads dimensioned to mesh with the internal
threads of said cap sleeve.
2. A supporting device as defined in claims 1, said expander means
further comprising an expander portion provided on said rod-shaped
means and engaging said expansion element for effecting expansion
of the same in response to said axial displacement of said
rod-shaped means in direction towards said trailing end
portion.
3. A supporting device as defined in claim 1, said rod-shaped means
having an outer diameter which is substantially smaller than the
inner diameter of said passage, so that said rod-shaped means is
received in said passage with clearance.
4. A supporting device as defined in claim 1; and further
comprising cooperating screwthreads provided on said leading end
portion of said supporting sleeve and on said expansion element,
respectively, for permitting releasable connection of the latter
with the former.
5. A supporting device for fractured tubular bones which have a
longitudinally extending curved interior cavity, comprising an
elongated supporting sleeve having a leading and a trailing end
portion and being curved in at least substantial conformance with
said cavity, said supporting sleeve being provided with a curved
longitudinal passage having a widened section at said trailing end
portion; an expansion element at said leading end portion located
forwardly thereof; expander means associated with said expansion
element, said expander means including rod-shaped means extending
through said passage between said end portions and adapted to
expand said element in response to axial displacement towards said
trailing end portion, and displacing means at least partially
received in said widened section in engagement with said rod-shaped
means and operative for effecting displacement thereof only axially
of said supporting sleeve in direction towards said trailing end
portion, said displacing means being a hollow internally threaded
cap sleeve having an open end facing away from said leading end
portion, and said rod-shaped means having external screw threads
which mesh with the internal threads of said cap sleeve, said
rod-shaped means having a length such that a terminal portion
thereof extends outwardly through said open end when said
rod-shaped means has been axially displaced by a distance requisite
for expanding said expansion element; and a cap unit configurated
for threading engagement with said terminal portion and having a
head adapted to bear against said bone.
6. A supporting device as defined in claim 5; further comprising an
annular member dimensioned to externally surround said trailing end
portion of said supporting sleeve; and cooperating
rotation-preventing portions provided on said trailing end portion
and on said annular member, respectively, said cap unit being
configurated for engaging said annular member and retaining it
against movement axially of said sleeve.
7. A supporting device as defined in claim 6, said annular member
having one axial end facing towards said leading end portion of
said sleeve; and wherein said rotation-preventing portions comprise
axially extending slots provided in said annular member extending
rearwardly from said one axial end thereof, and axially extending
ribs provided on said trailing end portion of said sleeve and
received in the respective slots.
8. A supporting device as defined in claim 6, said annular member
having an axial end facing away from said leading end portion; and
further comprising an annular component having a first portion
dimensioned to be receivable in said annular member at said axial
end thereof, and a second portion dimensioned to at least in part
overlie an axial endface of said annular member at said axial end
thereof.
9. A supporting device as defined in claim 8; further comprising a
hooked portion provided on one of said annular member and annular
component and being adapted to hook onto the edge of a hole which
is provided in said bone for insertion of said sleeve into said
cavity.
10. A supporting device as defined in claim 9, wherein said hooked
portion is provided on said annular member.
11. A supporting device as defined in claim 9, wherein said hooked
portion is provided on said annular component.
12. A supporting device for fractured tubular bones which have a
longitudinally extending curved interior cavity, comprising an
elongated supporting sleeve having a leading and a trailing end
portion and being curved in at least substantial conformance with
said cavity, said supporting sleeve being provided with a curved
longitudinal passage having a widened section at said trailing end
portion; an expansion element at said leading end portion located
forwardly thereof; expander means associated with said expansion
element, said expander means including rod-shaped means extending
through said passage between said end portions and adapted to
expand said element in response to axial displacement towards said
trailing end portion, and displacing means at least partially
received in said widened section in engagement with said rod-shaped
means and operative for effecting displacement thereof only axially
of said supporting sleeve in direction towards said trailing end
portion, said displacing means being a hollow internally threaded
cap sleeve having an open end facing away from said leading end
portion, and said rod-shaped means having external screw threads
which mesh with the internal threads of said cap sleeve, said
rod-shaped means having a length such that a terminal portion
thereof extends outwardly through said open end when said
rod-shaped means has been axially displaced by a distance requisite
for expanding said expansion element; and an extension rod having
an outer diameter smaller than the root diameter of said external
screw threads, a bore in an axial end face of said terminal
portion, and cooperating threads on said extension rod and in said
bore.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to a supporting device for
fractured bones, and more particularly to a supporting device for
fractured tubular bones having a longitudinally extending curved
interior cavity.
Devices for supporting and connecting fractured bones are already
known. It is, in fact, known to use expansion devices for such
purposes which are inserted into the bone urging the fracture
internally of the bone and connecting the bone fragments together.
However, such expansion devices heretofore have not been usable for
fractured tubular bones for reasons which are well known to those
conversant with this field. Heretofore fractures in tubular bones
having a longitudinally extending curved marrow-containing cavity
have been repaired by means of pins driven into the marrow-filled
interior cavity. The purpose is to provide for lateral securing and
also to hold together the fragments of the broken tubular bone.
However, the marrow cavity in tubular bones invariably has a
contour which converges and then diverges in longitudinal direction
of the bone, and as a result a longitudinally driven pin will
contact the interior wall bounding the bone cavity only over a
small region. The result is that the lateral securing effect, and
the retention of the bone fragments, afforded by such a pin is at
best marginal. It has also been proposed to enlarge the contact
surface by drilling open the bone marrow cavity, that is to enlarge
its diameter at the narrower points in order to obtain a greater
surface area and being able to use larger pins. This approach has
actually been put into use but with the unfortunate result that
infections occurred which in some cases resulted in wasting-away of
the bone in question.
A second approach to the problem of repairing fractures in tubular
bones has been to use a pin which is curved in conformity with the
curvature of the interior wall of the bone marrow cavity. This
does, in fact, improve lateral retention of the bone fragments to
some extent, but the fragments are not prevented from relative
longitudinal displacement because there is no way in which they can
be drawn together and held together and held together against
relative longitudinal movement. This second approach suffers from
still another disadvantage, in that although the lateral retention
of the bone fragments is somewhat improved, it is by no means as
good as it is desired to be. The reason for this is that the pin is
not fixed in that part of the bone marrow cavity which is the
divergent part, so that the pin can either turn or become displaced
in longitudinal direction when a load is applied to the bone in
question.
It is clear, therefore, that the present state of the art of
devices for supporting fractured tubular bones laterally and
longitudinally is not satisfactory and that improvements are higher
desirable.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide such
improvements.
More particularly it is an object of the invention to provide an
improved supporting device for fractured tubular bones which is not
possessed of the disadvantages outlined above with respect to the
prior art, and which affords the improvements which have been set
forth above as being desirable.
A concomitant object of the invention is to provide such a
supporting device which has a large contact area with the surface
bounding the bone marrow cavity of a fractured tubular bone, a
contact area which if possible should extend over the entire length
or substantially the entire length of the bone.
An additional object of the invention is to provide such a
supporting device which affords anchoring of the device in the bone
marrow cavity of a fractured tubular bone, and in particular in the
divergent portion of the cavity.
Still an additional object of the invention is to provide such a
device which is capable of retaining the bone fragments against
movement relative to one another in longitudinal direction.
In pursuance of these objects, and of others which will become
apparent hereafter, one feature of the invention resides in a
supporting device for fractured tubular bones having a
longitudinally extending curved interior cavity. Briefly stated,
such a supporting device may comprise an elongated supporting
sleeve having a leading and a trailing end portion and being curved
in at least substantial conformance with the cavity of the
fractured bone. The sleeve is provided with a curved longitudinal
passage having a widened section at the trailing end portion. An
expansion element is located at the leading end portion forwardly
thereof, and expander means is associated with the expansion
element. This expander means includes rod-shaped means extending
through the passage of the sleeve between the end portions thereof
and being adapted to expand the expander element in response to
axial displacement towards the trailing end. The expander means
further comprises displacing means at least partially received in
the widened section of the longitudinal passage of the sleeve,
being in engagement with the rod-shaped means and being operative
for effecting displacement thereof only axially of the sleeve in
direction towards the trailing end portion of the latter. Thus, no
rotation of the rod-shaped means is necessary or possible.
Tubular bones have a portion which hereafter will be identified as
"bulge." In order to permit insertion of the supporting device
according to the present invention, a hole is drilled into the
tubular bone in question at the bulge or in the region thereof, so
as to permit access to the interior bone marrow cavity. The
supporting device is now inserted through this hole into the bone
marrow cavity until the expander element of the device is located
in the divergent portion of the cavity, that is the portion which
follows the convergent portion and the narrow juncture at the end
of the convergent portion. When the device is so positioned, and it
must be kept in mind here that the device is bent in conformity
with the curvature of the bone marrow cavity of the bone itself,
the displacing means is utilized to rearwardly displace the
rod-shaped means in a sense causing the expander element to become
expanded and thus to be anchored in the bone marrow cavity.
The displacing means is in form of a sleeve-shaped element which
advantageously is made so long that the rearward axial displacement
of the rod-shaped means does not cause the trailing end of the
rod-shaped means to move out of the sleeve-shaped displacing means,
so that this rearward end is and remains concealed therewithin.
This is advantageous because the development of a pressure point or
position, resulting from extending of the rearward end of the
rod-shaped means out beyond the sleeve-shaped displacing means, is
thereby avoided. This could lead to maximum stress upon the bone
when a load is placed on the latter, due to the diameter of the
rod-shaped means which is, of course, much smaller than that of the
sleeve-shaped displacing means surrounding it.
As has been pointed out before, the supporting device is curved in
at least substantial conformance with the curvature of the bone
marrow cavity. This means that when it is inserted it is in contact
with the interior wall bounding the cavity over a larger region
than was heretofore possible. The fractured tubular bone is thereby
laterally secured against relative displacement of the bone
fragments to an extent not previously achieved, and callus may thus
be formed in the shortest possible time at the fracture line,
resulting in re-connection of the bone fragments with one another.
It has been found that using the supporting device according to the
present invention, the duration of hospitalization or other medical
attention required in the case of a fractured tubular bone is
substantially reduced over that required where a similar fracture
is repaired with one of the pins according to the prior art.
Furthermore, the fact that the device according to the present
invention can be anchored by expansion of the expansion element
also assures that stress can be transmitted to the fractured
tubular bone much earlier than was heretofore possible.
In addition, the anchoring of the device via the expansion element
thereof eliminates the need for the additional use of wires or of
pins driven in from the side of the bone to secure the support
element against shifting or twisting in the bone marrow cavity,
because such shifting or twisting is reliably precluded.
The list of advantages obtained with the present supporting device
is not, however, exhausted with what has been set forth above. Thus
it is pointed out that the supporting device may be so constructed
as to prevent the bone fragments from performing relative movements
in longitudinal direction of the bone. Normally a certain amount of
retention of the bone fragments against such longitudinal movement
is provided by sinues and muscles surrounding the bone. However, in
many cases this is not sufficient, a condition which is especially
true when the sinues and muscles are themselves affected by the
fracture. The supporting device according to the present invention
may be so constructed as to draw the bone fragments axially
together and maintain them held together, so that they can be
pressed into tight abutment at the fracture and be held in this
position.
It is advantageous if the rod-shaped means, for instance a rod
which is threaded over part or all of its length on the exterior,
has a diameter which is considerably smaller than the diameter of
the interior longitudinal passage in the supporting sleeve itself.
This means that the rod can be received in this passage with
clearance and the difference in the diameters between the rod and
the passage will prevent tilting and jamming of the rod in the
passage during the expansion of the expander element.
The expander element, incidentally, is advantageously made so that
it can be connected with and disconnected from the supporting
sleeve, advantageously by means of cooperating screw threads. Some
or all of the components of the supporting device may be
constructed of V2A or V4A steel i.e. X12CRNI188 or X5CRNlMO1810,
that is steel which can be worked only with difficulty with cutting
tools and which is acid and corrosion resistant. The sleeve and the
expansion element can be produced separately and can be made
connectable with one another, and one advantage of this is the fact
that the bore or passage which must be provided in the interior of
the supporting sleeve can now be shortened by the length of the
expansion element itself, meaning that shorter and more stable
drills may be used in forming the bore.
Still another advantage of making the expansion element and
supporting sleeve separate and releasably connectable comes from
the fact that the stocking requirements for the components become
simplified. This means that it is now only necessary to have a
stock of the supporting sleeve on hand in various lengths, whereas
the expansion element can always be of one and the same type and
dimension (only one type of expansion element need be kept in
stock) and can be connected to a supporting sleeve of requisite
length when a device is required.
The invention also contemplates an embodiment wherein the threaded
rod may be of such a length that it extends beyond the
sleeve-shaped displacing means after it has been withdrawn
rearwardly to the extent necessary to effect expansion of the
expansion element. Thus, a portion of the threaded rod will then
extend rearwardly out of the sleeve-shaped displacing means and a
cap nut may be threaded onto this portion, being supported against
the bone in order to draw the bone fragments together. This
embodiment also permits the longitudinal pressing together and
holding together of the bone fragments, independently of the
anchoring of the device in the bone.
Another advantageous embodiment of the invention proposes that an
extension may be releasably attached to that portion of the
threaded rod which extends rearwardly beyond the sleeve-shaped
displacing means when the rod has been retracted to the extent
necessary to effect expansion of the expansion element. The
exterior diameter of this extension should be smaller than the root
diameter of the exterior thread of the threaded rod, so that it can
be threaded into an axial taped bore provided in the trailing end
of the threaded rod. Providing of this threaded extension offers
the surgeon the possibility of completely inserting the threaded
rod itself without any difficulty into the bone marrow cavity,
because he has the extension available for engaging purposes. In
addition, the somewhat smaller exterior diameter of the extension
as opposed to the root diameter of the threads on the threaded rod,
means that the various components which are to be placed over or
onto the trailing end of the threaded rod --such as for instance
the sleeve-shaped displacing means -- can be readily slipped over
the extension and put in place. Thus the extension facilitates the
fitting of the device according to the present invention into the
bone, and shortens the time required for the operation because the
surgeon is relieved of the necessity for having to look into the
hole drilled in the bone in order to find the beginning of the
screw thread and the trailing end of the threaded rod, where onto
to thread for instance the sleeve-shaped displacing means.
The novel features which are considered as characteristic for the
invention are set forth in particular in the appended claims. The
invention itself, however, both as to its construction and its
method of operation, together with additional objects and
advantages thereof, will be best understood from the following
description of specific embodiments when read in connection with
the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 illustrates one embodiment of the invention in an axial
section through a fractured tubular bone;
FIG. 2 is a fragmentary detail view, partly sectioned, illustrating
a further embodiment of the invention; and
FIG. 3 is a view similar to FIG. 2 but illustrating still another
embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Discussing the drawing in detail, and firstly the embodiment
illustrated in FIG. 1, it will be seen that in this embodiment the
supporting device according to the present invention is identified
with reference numeral 1 in toto and its various components
advantageously, although not necessarily, may be made of V2A or V4A
steel. The device 1 has an elongated supporting sleeve 2 which is
curved in at least substantial conformance with the curvature of a
longitudinally extending bone marrow cavity which is inherently
present in all tubular bones. The bone is shown as being fractured
twice, thus being composed of the bone fragments 12a, 12b and 12c,
with the two fracture lines being indicated with reference numeral
13.
Secured releasably to the leading end portion of the sleeve 2,
which for this purpose is provided with an internal thread 17, is
an expansion element 3 whose construction is shown in FIG. 1. An
elongated rod 5 is provided for expanding the expansion element 3,
carrying at its front end an expander portion 6 which, when the rod
5 is moved axially rearwardly, is drawn between the shanks 15 into
which the expansion element 3 is subdivided by a plurality of
axially extending slots, and which are spread radially in response
to such rearward movement of the rod 5 and the portion 6. The
expansion element 3 is provided with an exterior screw thread 16
which meshes with the interior screwthread 17 of the sleeve 2.
The rearward axial displacement of the rod 5 is effected in this
embodiment by means of a sleeve-shaped displacing element 4 which
is internally threaded and at least in part received and guided in
a widened portion 7 of the longitudinal passage of the sleeve 2 at
the trailing end of the latter. The element 4 can abut against and
be supported either by the shoulder 8 or the rearward end face of
the sleeve 2 itself.
The axial length of the element 4 is so selected that when it has
been rotated in a sense withdrawing the rod 5 whose exterior
screwthreads mesh with the interior screwthreads of the element 4,
in axially rearward direction, and when the rod 5 has been
rearwardly withdrawn to the extent necessary to fully expand the
expansion element 3, there will still be sufficient room left in
the interior passage of the element 4 to permit a cap screw 9 to be
threaded into the open rear end of the element 4 as shown. In the
embodiment of FIG. 1 the head 10 of the screw 9 bears via a washer
11 --provided to further increase the surface area of contact
--against the bone fragment 12a, so that after the expansion
element 3 has been expanded and anchored in the portion of the
marrow cavity located in the bone fragment 12c, the three bone
fragments 12a, 12b and 12c can be drawn axially together by means
of the screw 9, thus permitting the bone fragments to be tightly
abutted at the fracture lines 13.
Clamping and tilting of the rod 5 in the bore of the sleeve 2
during the rearward axial withdrawing of the rod 5 is prevented by
providing rotation-preventing portions 14 on the expanding portion
6 which extend into the slots subdividing the element 3 into the
shanks 15, so that the portion 6 and therefore the rod 5 with which
it is fast, are prevented from turning.
It is of course evident from FIG. 1 that the device 1 is curved in
accordance with or in at least substantial conformance with the
curvature of the bone marrow cavity 18 in the bone 12a, 12b and
12c, so that it will contact the inner surface 19 bounding the
cavity 18, over a wide range. The lateral fixation of the bone
fragments with reference to one another which can be obtained in
this manner with the device according to the present invention is
excellent and far better than heretofore obtained.
In the embodiment of FIG. 2 like reference numerals designate like
elements as in the embodiment of FIG. 1. Here only a single bone
fragment 12 is shown, and only a portion of the device 1, it being
understood that the remainder of the device 1 which is not
illustrated corresponds to that portion which has been shown in
FIG. 1.
In the embodiment of FIG. 2 the element 4 is of a somewhat
different configuration and shorter than the element 4 shown in 1,
being threaded onto the trailing end portion of the rod 5 and
abutting against the end face of the sleeve 2. In order to in
particular facilitate the positioning and threading of the element
4 onto the rod 5, but also to facilitate insertion of the rod 5
itself, a rod-shaped extension 25 is provided whose outer diameter
is smaller than the root diameter of the exterior threads 33 on the
rod 5. The latter is provided for this purpose with an axially
extending tapped bore in its rear free end, this bore being
identified with reference numeral 26 and the extension 25 being
removably threadable into the tapped bore 26. The element 4 is then
simply slipped over the extension 25 until the thread 33 of the rod
5 is reached at which point the element 4 is then turned in a sense
threading it onto the thread 33. Such threading, and in particular
tightening of the element 4 in a sense rearwardly displacing the
rod 5 in order to expand the expansion element 3 (FIG. 1) is
effected with a wrench of the Allen type which must, however, have
a central bore through which the extension 25 can pass. As in the
embodiment of FIG. 1, when the element 4 is tightened the rod 5
will perform movement only in one direction, namely in axially
rearward direction to thereby cause expansion of the expansion
element 3.
In the embodiment of FIG. 2 the length of the rod 5 has been so
chosen that when it has been withdrawn to the maximum extent
necessary to issue a proper expansion of the element 3, the rear
portion of the rod 5 will extend rearwardly beyond the element 4.
Onto the thus exposed rear portion there is now threaded a cap nut
50 which is also provided with a central bore so that it can be
slipped over the extension 25. When the cap nut 50 is tightened the
head 51 abuts against a retaining washer 52 and exerts sufficient
pressure to draw the bone fragments longitudinally together. The
washer 52 has two lugs 53a and 53b which are so bent (see FIG. 2)
as to overlap at least in part the exterior of the bone adjacent
the hole which has been drilled in the same in order to gain access
to the interior cavity. They are bent at the edges 54 bounding this
hole in the manner necessary to overlie the exterior of the bone as
illustrated, and they serve to hold --in conjunction with the head
51 of the nut 50-- the washer 52 in a position in which it extends
almost at right angles to the elongation of the sleeve 2, covering
at least a part of the opening drilled for access to the interior
of the bone cavity. When this has been accomplished, the extension
25 is removed, for which reason it has been illustrated in broken
lines in FIG. 2.
It is also advantageous, particularly where the device is to be
used for repairing a fractured tubular leg bone, in which case the
device must be inserted on the front side of the bone which extends
almost parallel with the elongation of the leg, to support the cap
nut with a sleeve which can be attached to the end of the
supporting device opposite the insertion and, that is the trailing
end, and which is secured against twisting in relation to the
supporting device and can be retained against the bone by means of
an attached hook-shaped lug that can be hooked onto an edge
bounding the hole which has been provided in the bone for insertion
of the device.
With such a construction, and when the bone fragments are drawn
together, the lug will take up the axial forces acting in
longitudinal direction of the device while the torque produced by
the unilateral support of the sleeve is absorbed by the contact of
the sleeve with the interior wall bounding the bone marrow cavity.
The length chosen for the sleeve depends on the magnitude of the
torque loading to be expected, and in order to keep the surface
portion of the sleeve against the interior wall bounding the marrow
cavity as small as possible, a long sleeve should be used when the
torque is large, and a short sleeve when the torque is small.
The space requirement for such a sleeve is very small since only
one lug attached to this sleeve need be hooked onto an edge of the
opening provided in the bone, in order to obtain proper support of
the latter. Furthermore, the sleeve can take up great loads because
a very good torque absorption is achieved, due to favorable lever
relationships and the contact of the sleeve with the interior wall
bounding the marrow cavity. In this construction the sleeve is
secured against twisting relative to the bone by hooking the lug
onto the edge of the opening through which the device is inserted,
and it is only necessary to secure the element against twisting in
relation to the sleeve and thus to the bone.
The sleeve of a device which is provided with fins preventing
twisting, such fins being located at the trailing end, may be
provided with slots which extend from the front end in longitudinal
direction of the sleeve and wherein the fins are guided. The device
is thus secured against twisting relative to the sleeve which in
turn is secured against twisting relative to the bone by the lug
hooked into the access opening in the bone.
An additional sleeve may also be inserted into the rear end of the
first-mentioned sleeve, namely the sleeve supporting the cap nut,
and this additional sleeve may contain a flange covering the front
face of the first-mentioned sleeve and serves for enlargement of
the contact area with the cap nut, thus assuring that the surface
pressure between cap and cap nut and the front face of the sleeve
is not unduly large.
The hook-shaped lug may also be provided at this additional sleeve
instead of at the first-mentioned one, an arrangement which has the
advantage that the longer sleeve which can be pushed over the rear
end of the device may be manufactured from a single tube. Because
the device is predominantly produced from V2A or V4A steel, in
accordance with a currently preferred concept, it is simpler and
less expensive from a manufacturing point of view to provide the
hook-shaped lug at the shorter additional sleeve which is provided
with a flange for improving the contact surface.
Such an embodiment is illustrated in FIG. 3 wherein again like
reference numerals designate like components as in the preceding
Figures. A single bone fragment 12 is again shown, and it will be
seen that the element 4 is threaded onto the trailing end of the
expander rod 5. All such portions of the device 1 which have not
been shown in FIG. 3 are identical with the ones which have been
shown in FIG. 1.
In the embodiment of FIG. 3 a further sleeve 60 is pushed over the
trailing end of the device 1 and is provided with a hook-shaped lug
62 (which may also be provided on a further sleeve 61) which is
hooked over an edge 54 bounding the access opening drilled into the
bone in order to insert the device 1. Threaded onto that portion of
the rod 5 which extends rearwardly beyond the element 4 is a cap
nut 50 which again serves to draw the bone fragments together, and
whose head 51 abuts either against the end face of the sleeve 60 or
against the portion 63 of the additional sleeve 61, which portion
63 overlies the end face of the sleeve 60. The sleeve 61 can be
pushed into the rear end of the sleeve 60, as illustrated.
The sleeve 60 is prevented from rotation with respect to the device
1 by being formed with longitudinal slots 64 extending rearwardly
from its front end, and into which ribs or fins 65 of the element 1
extend to prevent relative rotation.
When the device has been installed the bone fragments (only the
fragment 12 being shown) are drawn axially together by the head of
the nut 50, and pressed together until tied abutment is achieved at
the fracture lines (compare FIG. 1) so that callus can form which
will reunite the fragments.
The device 1 is inserted deeply enough into the cavity of the bone,
and anchored therein, to assure that after it is completely
installed neither the nut 50 nor the rod 5 extend outwardly beyond
the access opening drilled in the bone, thereby assuring that no
pressure points can develop which might cause difficulty or
damage.
Of course, the device 1 will ordinarily be removed when the bone
fracture is healed, and for this purpose an internal thread 66 may
be provided into which a screw, a bolt or an extracting device can
be threaded by means of which the device 1 can be withdrawn from
the bone cavity when the time to do so has come.
It will be understood that each of the elements described above, or
two or more together, may also find a useful application in other
types of construction differing from the types described above.
While the invention has been illustrated and described as embodied
in a supporting device for fractured tubular bones, it is not
intended to be limited to the details shown, since various
modifications and structural changes may be made without departing
in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the
gist of the present invention that others can by applying current
knowledge readily adapt it for various applications without
omitting features that, from the standpoint of prior art, fairly
constitute essential characteristics of the generic or specific
aspects of this invention and, therefore, such adaptations should
and are intended to be comprehended within the meaning and range of
equivalence of the following claims.
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