U.S. patent application number 09/827861 was filed with the patent office on 2001-08-02 for device for postoperative fixation back into the cranium of a plug of bone removed therefrom during a surgical operation.
Invention is credited to Lerch, Karl-Dieter.
Application Number | 20010011173 09/827861 |
Document ID | / |
Family ID | 7784416 |
Filed Date | 2001-08-02 |
United States Patent
Application |
20010011173 |
Kind Code |
A1 |
Lerch, Karl-Dieter |
August 2, 2001 |
Device for postoperative fixation back into the cranium of a plug
of bone removed therefrom during a surgical operation
Abstract
A device for postoperative fixation back into the cranium of a
plug of bone removed therefrom during a surgical operation. The
device comprises a pin (11) and two concavoconvex disks (21 &
22) of a physiologically compatible metal or metal compound. The
pin has a flat head (111) at one end and one (21) of the disks
comes to rest against the head. Each disk has row of teeth (213
& 223), extending along the edge of the concave side and a bore
(211 & 221) through the center. The shaft (112) of the pin fits
into the bores. The disks can be mounted on the shaft with the
teeth on each one facing the teeth on the other. The second disk
can be fastened to the shaft.
Inventors: |
Lerch, Karl-Dieter; (Witten,
DE) |
Correspondence
Address: |
KENYON & KENYON
ONE BROADWAY
NEW YORK
NY
10004
US
|
Family ID: |
7784416 |
Appl. No.: |
09/827861 |
Filed: |
April 6, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09827861 |
Apr 6, 2001 |
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09494599 |
Jan 31, 2000 |
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09494599 |
Jan 31, 2000 |
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09088175 |
Jun 1, 1998 |
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6068631 |
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09088175 |
Jun 1, 1998 |
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08790071 |
Jan 28, 1997 |
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5800436 |
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Current U.S.
Class: |
606/324 |
Current CPC
Class: |
A61B 17/683 20130101;
A61B 17/688 20130101 |
Class at
Publication: |
606/72 |
International
Class: |
A61B 017/58 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 3, 1996 |
DE |
196 03 887.1 |
Claims
What is claimed is:
1. A device for postoperative fixation back into an opening in the
cranium of a plug of bone removed therefrom during a surgical
operation, wherein the plug is to be repositioned in the opening
such that the space between the plug and the surrounding cranial
bone is approximately the width of the kerf formed during the
surgical operation and the internal and external surfaces of the
plug are to be held in alignment with the adjacent internal and
external surfaces of the surrounding cranial bone, the device
comprising the following elements formed of a physiologically
compatible substance: a pin having a shaft that is extendable
through the space between the plug and the surrounding cranial
bone, the shaft having a proximal end and a distal end; a
substantially rigid first disk mounted centrally on the shaft of
the pin at the proximal end, the first disk having an inner surface
oriented toward the distal end of shaft and an opposite outer
surface, the first disk being positionable interiorly of the
opening in the cranium such that the inner surface faces the
internal surface of the plug and the adjacent internal surface of
the surrounding cranial bone; a substantially rigid second disk
mounted centrally on the shaft of the pin at the distal end, the
second disk having a bore formed therein through which the shaft of
the pin extends, an inner surface facing the first disk, and an
opposite outer surface, the second disk being positionable
exteriorly of the opening in the cranium such that the inner
surface faces the external surface of the plug and the adjacent
external surface of the surrounding cranial bone, the second disk
being movable along the shaft towards the first disk from a first
position wherein the first or the second disk is out of engagement
with the plug and surrounding cranial bone to a second position
wherein the first and second disks engage and align the internal
and external surfaces of the plug and surrounding cranial bone; and
means for retaining the second disk in the second position.
2. A device in accordance with claim 1 wherein the first disk
includes teeth formed on the periphery thereof that extend toward
the second disk.
3. A device in accordance with claim 1 wherein the second disk
includes teeth formed on the periphery thereof that extend toward
the first disk.
4. A device in accordance with claim 1 wherein the retaining means
comprises notches formed along at least a portion of the length of
the shaft of the pin, the notches restraining movement of the
second disk along the shaft in the direction opposite the first
disk.
5. A device in accordance with claim 1 wherein the bore of the
second disk is sized so as to fit snugly around the shaft, and said
retaining means comprises frictional engagement between the second
disk and the shaft.
6. A device in accordance with claim 1 wherein the pin has a
substantially flat head formed at the proximal end of the shaft,
the first disk includes a bore through which the shaft extends, and
the outer surface of said first disk rests against the head.
7. A device in accordance with claim 1 wherein each of the first
and second disks is concavoconvex in shape and each is oriented on
the shaft such that its inner surface is the concave side.
8. A device in accordance with claim 7 wherein each of the first
and second disks is deformed in its center in a direction opposite
its concavoconvexity.
9. A device as defined in claim 1, wherein said physiologically
compatible substance is a metallic substance.
10. A device in accordance with claim 1, wherein said first disk
includes perforations uniformly distributed within the area of said
first disk between the center and the circumference of said first
disk.
11. A device according to claim 1, wherein said second disk
includes perforations uniformly distributed within the area of said
second disk between the center and the circumference of said second
disk.
Description
[0001] The present application is a continuation of U.S. patent
Ser. No. 088,175, filed Jun. 1, 1998, which is a continuation of
U.S. patent application Ser. No. 790,071, filed Jan. 28, 1997, now
U.S. Pat. No. 5,800,436.
BACKGROUND OF THE INVENTION
[0002] The present background of the invention concerns a device
for postoperative fixation back into the cranium of a plug of bone
removed therefrom during a surgical operation.
[0003] It is often necessary during brain surgery to remove a plug
of bone from the cranium to provide the surgeon with access to the
field of operation. The plug is sawed out and must be replaced in
the cranium after the operation and fixed thereto. Such plugs have
long been fixed back into the rest of the cranium by suturing with
loops of steel wire that extend through both and then twisting
together the projecting ends of the emplaced loops. The contact
between the plug and the rest of the cranium is relatively
unstable, however. The two halves do not fuse together very well.
The scalp can also become inflamed. Another drawback to such an
approach is that the wire considerably distorts the images obtained
in postoperative computerized tomography and accordingly impedes
definitive interpretation of the soft structures of the brain.
Although using nonresorbable and physiologically compatible thread
instead of wire does eliminate the last-mentioned drawback, the
fixation of the plug to the rest of the skull is still unstable.
The two parts can also be fixed with thin plates of compatible
metal, titanium for instance (EP A 0 510 390). Such plates bridge
the abutment between the parts and are screwed to both, also
closing off bores introduced into the cranium prior to section.
This approach, however, is also not very satisfactory. It is both
complicated and time-consuming and hence not inexpensive.
SUMMARY OF THE INVENTION
[0004] With the aforesaid state of the art as a point of departure,
the object of the present invention is a simpler and more rapid
device for accurate and permanent postoperative fixation back into
the cranium of a plug of bone removed therefrom during a surgical
operation.
[0005] This object is attained in accordance with the present
invention in a device of the aforesaid genus comprising a pin and
two concavoconvex disks of a physiologically compatible metal or
metal compound. The pin has a flat head at one end and one of the
disks comes to rest against the head. Each disk has row of teeth
extending along the edge of the concave side and a bore through the
center. The shaft of the pin fits into the bore. The disks can be
mounted on the shaft with the teeth on each one facing the teeth on
the other. The second disk can be fastened to the shaft.
[0006] The inner disks in the aforesaid fixation device in
accordance with the present invention are secured to the pins in
the vicinity of the head. The disks are then inserted through a
slightly larger recess in the circumference of the plug, below the
parts of the joint, with the shaft of the pin projecting out of the
kerf between the plug and the rest of the cranium. The outer disk
is then mounted over the section of pin projecting out of the kerf.
The two disks are then approached until their teeth bite into the
edges of both the plug and of the rest of the cranium. The second
disk is then secured to the shaft.
[0007] Titanium is particularly appropriate for the physiologically
compatible metal. Such titanium alloys as Ti.sub.6A.sub.6Va are
also appropriate. A device made of titanium is of advantage because
it will not distort postoperative computerized- tomography images.
The inner disk can be mounted more stable on the shaft of the pin
if the transition between the head of the pin and the shaft is
conical and dimensioned to ensure that a disk resting against the
head will be forced tight around the shaft. Slits can also extend
radially outward from the bore through the first disk to be mounted
on the shaft. The center of the disk can be depressed. Areas can be
removed from the disks at regular intervals between the bore and
the edge to conserve material. The device can be applied to the two
halves of bone by a procedure similar in principle to blind
riveting. Notches can accordingly be introduced into each shaft to
prevent the second disk mounted thereon from sliding away from the
head of the pin. If the second disk on the shaft is deformed in a
direction opposite that of its concavoconvexity, the deformation
alone will secure it to the shaft by compression. The shaft can
also be threaded and accommodate a nut. The nut can be tightened
against the second disk. The second disk will in every case be
displaced until its teeth engage the two halves of the joint,
creating the desired fixation of the plug back into the rest of the
cranium at the adjacent edges.
[0008] The novel device can be easily and rapidly manipulated and
accomplishes the desired accurate and permanent postoperative
fixation back into the cranium of a plug of bone removed therefrom
during a surgical operation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention will now be specified with reference
to the accompanying drawing wherein
[0010] FIG. 1 is an exploded view of the device in accordance with
the present invention,
[0011] FIG. 2 is a view in the direction indicated by arrow II in
FIG. 1 of one embodiment of the first disk mounted over the shaft
of the pin,
[0012] FIG. 3 is a view in the direction indicated by arrow III in
FIG. 1 of one embodiment of the second disk mounted over the shaft
of the pin,
[0013] FIG. 4 is a longitudinal section of the components of the
device assembled,
[0014] FIG. 5 illustrates how the device in accordance with the
present invention can be employed,
[0015] FIG. 6 is a section along the line VI-VI in FIG. 5,
[0016] FIG. 7 is a schematic view and shows another embodiment of
the present invention, and
[0017] FIG. 8 is a schematic view of a still further embodiment
according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] A device for postoperatively fixing back into the cranium a
plug of bone removed therefrom during a surgical operation
comprises a pin 11 and two concavoconvex disks 21 and 22. The pin
comprises a shaft 112 and a head 111, Disk 21, the inner disk, is
mounted on the shaft first and comes to rest against the inner
surface of the plug and of the rest of the cranium that are to be
united. Disk 22, the outer disk, is mounted on the shaft next and
comes to rest against the outer surface of the plug and the rest of
the cranium. There is a hole 211 through the center of each disk 21
and a hole 221 through the center of each disk 22. The shaft 112 of
pin 11 extends through the holes 211 and 221 of the disks in the
assembled device. A raw of teeth 213 extends along the edge 212 of
the concave side of disk 21, and a row of teeth 223 extends along
the edge 222 of the concave side of disk 22. As will be evident
from FIGS. 1 and 4, disks 21 and 22 are mounted on the shaft 112 of
pin 11 with their teeth facing each other.
[0019] Shaft 112 fits tightly in the hole 211 through disk 21. Any
disk can be provided as illustrated in FIG. 2 with slits 214
extending radially outward from the hole 211 through its center. If
the transition between the head 111 and the shaft 112 of pin 11 is
conical, slits 214 will as is desirable accurately position the
disk in relation to the pin, both of which will accordingly support
both the plug and the rest of the cranium once the device has been
emplaced, The area between the hole through the center of any disk
and its circumference can also be provided as illustrated in FIG. 3
with perforations 226 to conserve material and decrease weight.
Each disk can have both slits 214 and perforations 226.
[0020] FIGS. 5 and 6 illustrate how the device is employed. FIG. 5
illustrates part of an adult cranium 31 from which a plug 32 of
bone has been sawn to provide access to the brain, which is
available to the surgeon through aperture 33. A recess 321 slightly
larger than the disks has been removed from plug 32 at its
circumference. once the operation is over, the plug is returned to
the aperture 33. Inner disks 22 are mounted on the shafts 112 of
pins 1. The inner disks are inserted one by one through recess 321
with the shafts projecting out and slid along the inner surface of
the plug and residual cranium with the shafts extending out of kerf
331 in the directions indicated by arrows A in FIG. 5 until they
arrive at the point where they are to be positioned. outer disks 22
are now mounted on the shafts of the pins in situ. The outer disks
are finally secured to the shafts with a tool of the type employed
to fasten blind rivets. The tool forces outer disks 22 and inner
disks 21 together in the direction indicated by arrow B in FIG. 6
until the teeth on each disk bite into the tissue of the plug and
of the residual cranium, securing the two together. The section of
each shaft extending out beyond the outer disk is now trimmed off.
The shaft can alternatively be threaded, and the disks forced
together over the threads until the teeth bite into the tissue.
[0021] Thus, in another embodiment sown in FIG. 7, the shaft 112 of
the pin 11 has notches 112c engaging the outer surface of the
second disk 22 and forcing it towards the head 111 of the pin.
[0022] In the embodiment of FIG. 8, the shaft of the pin 11 has a
thread 112a and accommodates a nut 112b that can be screwed against
the second disk 22.
* * * * *