U.S. patent number 3,732,621 [Application Number 05/123,707] was granted by the patent office on 1973-05-15 for permanently implantable fixture means for prothesis and the like.
This patent grant is currently assigned to AGA Aktiebolag. Invention is credited to Bertil I. Bostrom.
United States Patent |
3,732,621 |
Bostrom |
May 15, 1973 |
PERMANENTLY IMPLANTABLE FIXTURE MEANS FOR PROTHESIS AND THE
LIKE
Abstract
As a permanently implantable fixture means for prosthesis and
the like in a human body, especially for implanting a dental
prosthetic structure, a means composed by at least two parts has
been proposed for attaching the prosthetic structure to bone
tissue. A first part of the attachment unit is intended to be
applied in such a way in the bone tissue that it will remain
embedded in said tissue during all of the time required for healing
the damage which occurs when the first part is attached to the bone
and while the bone tissue grows into the attachment, and a second
part of the attachment unit, serving as mounting unit for the
prosthetic structure and so shaped that it may be attached to the
first part of the attachment unit and pass through such weak tissue
covering the bone tissue. The mounting unit is intended to combine
the attachment unit inserted into the bone tissue with a prosthetic
structure located outside of the weak tissue. Such permanently
implantable attachment means have been used for permanently
attaching dental prosthetic structure to the jawbone in human
bodies. The jawbones rather often have a narrow cross-section, and
the longitudinal direction of the cross-section may be diverge
sharply at different parts of the same jaw and/or the same jawbone
but especially between the upper jaw and the lower jaw. This, among
other reasons, results in so-called over-bite or under-bite,
respectively. As the attachment units must, for technical reasons,
be well centered in the jawbone, the longitudinal directions of the
attachment units will not always be in alignment mutually in the
same jaw, nor between the upper jaw and the lower jaw. This is a
serious disadvantage, because the longitudinal direction of the
teeth in the prosthetic structure should be in alignment with the
longitudinal direction of the attachment unit. A compromise between
these demands either a weak or completely unsatisfactory attachment
in the jawbone or non-aligned prosthetic structure. Therefore,
there is a need for an attachment means of the kind indicated
above, in which the said first part attached to the jawbone may
form an angle with the said second part to which the prosthetic
structure is attached.
Inventors: |
Bostrom; Bertil I. (Taby,
SW) |
Assignee: |
AGA Aktiebolag (Ligingo near
Stockholm, SW)
|
Family
ID: |
20263720 |
Appl.
No.: |
05/123,707 |
Filed: |
March 12, 1971 |
Foreign Application Priority Data
|
|
|
|
|
Mar 25, 1970 [SW] |
|
|
4210/70 |
|
Current U.S.
Class: |
433/174 |
Current CPC
Class: |
A61C
8/005 (20130101); A61C 8/0022 (20130101); A61C
8/0048 (20130101); A61C 8/0069 (20130101); A61C
8/0053 (20130101) |
Current International
Class: |
A61C
8/00 (20060101); A61c 013/00 () |
Field of
Search: |
;32/1A,10,11,12,13 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Peshock; Robert
Claims
I claim:
1. A prosthetic device comprising:
a first part having means to be permanently implanted into a bone
such that the bone tissue grows into the first part,
a second part including means for attaching the prosthetic
structure thereon,
and a joint connecting said first and second parts, said joint
being a universal joint permitting at least limited universal
movement of the second part relative to the first part, and said
joint including means for locking the universal joint in any
selected position within the range of said limited universal
movement to prevent further relative movement of the first and
second parts,
and including means for separating said first and second parts from
each other in the vicinity of said universal joint.
2. A prosthetic device according to claim 1, in which said
universal joint is a ball and socket joint and wherein the portion
of said second part adjacent the joint is adapted to pass through
the soft tissue covering the bone tissue into which the first part
is permanently implanted.
3. A prosthetic device according to claim 2, wherein the ball of
the ball joint is attached to one of said parts and is embraced by
a ball claw which is attached to the other of said parts.
4. A prosthetic device according to claim 2, wherein the ball is at
least substantially spherical and is attached by means of a neck to
its respective part.
5. A prosthetic device according to claim 2, said ball being formed
as an elipsoid, ovaloid or the like, and including a pin connecting
said ball to the first part.
6. A prosthetic device according to claim 2, said ball being
substantially semi-spherical and formed integrally with one of said
parts and the socket embracing the semi-spherical surface and
attached to the other of said parts, and including a stretching
means running through the ball and socket joint and urging said
ball and socket together.
7. A prosthetic device according to claim 2, said ball being
substantially spherical and resting in sockets in each of the two
said parts.
8. A prosthetic device according to claim 3, said ball claw having
an opening, and a pin connected to the ball and extending through
said opening and connected to the part other than that part to
which the ball claw is connected.
9. A prosthetic device according to claim 6, wherein said
stretching means includes at least one substantially conical recess
passing through the ball for carrying the said stretching
means.
10. A prosthetic device according to claim 9, wherein the ball is
substantially spherical and includes a pair of inwardly converging
conical recesses which meet at the center of the ball to form an
opening completely through the ball for said stretching means.
11. A prosthetic device according to claim 2, wherein said locking
means comprises a spring means for urging the ball against its
socket.
12. A prosthetic device according to claim 11, including a ball
claw embracing the said ball, and wherein said locking means
includes a threaded engagement between a pin integral with one of
said parts and said ball for displacing the ball relative to the
ball claw for urging these two parts together.
13. A prosthetic device according to claim 11, wherein said locking
means includes stretching means running through the ball and socket
joint, the stretching means being attached at one of its ends to
one of said first and second parts, and the other end of the
stretching means being attached to the other of said first and
second parts, and at least one of said parts being displaceable by
means of a screw thread arrangement in the axial direction under
the stretching of stretching means.
14. A prosthetic device according to claim 3, wherein the ball claw
is provided on its outer surface with a profile which facilitates
engaging the ball claw to turn the same.
15. A prosthetic device according to claim 3, including a sleeve
contacting the outer side of the ball claw with a partially concave
surface to form said socket, and a spring means for urging the ball
and sleeve together.
16. A prosthetic device according to claim 15, said sleeve being
provided on its outside surface with a profile to facilitate
turning the same.
17. A prosthetic device according to claim 3, the said ball in the
ball joint being incompletely spherical, a spherical portion of the
ball engaging the ball claw, and a non-spherical portion of the
ball engaging a spring arranged to urge the ball against the ball
claw.
18. A prosthetic device according to claim 17, said ball including
a pin for connecting the ball with one of said parts, said pin
forming a seat for said spring.
19. A prosthetic device according to claim 18, said claw being
generally spherical and embracing the ball, said spring resting
against a spherical portion of said ball claw.
20. A prosthetic device according to claim 2, including an
intermediate part, a first ball and socket joint connecting said
intermediate part to said first part and a second ball and socket
joint connecting said intermediate part to the said second part.
Description
The present invention refers to an arrangement in attachment means
of the above indicated kind, by which said need is satisfied.
According to the invention, there is provided between the part of
the attachment means intended to grow together with the bone
tissue, on the one hand, and the part of the attachment means which
carries up the prosthetic structure on the other hand, a ball joint
like arrangement, comprising at least one joint but perhaps two or
more joints.
Further details of the invention will be apparent from the
following description in connection with the attached drawings,
showing a number of different forms of execution of the invention.
However, it is understood that the invention shall not be limited
to one or more or all of these forms of execution, but that all
different modifications or combinations between the different forms
of execution may be made within the different parts of the same jaw
and/or the same jaw bone but in first place between the upper jaw
and the lower jaw. This, amongst others, results in what is called
over-bite or under-bite, respectively. As the attachment units have
for load technical reasons to be well centered in the jaw bones,
the longitudinal directions of the attachment units will not always
be in agreement mutually in the same jaw, nor between the upper jaw
and the lower jaw. This means a serious disadvantage, because the
longitudinal direction of the teeth in the prothesis should be in
agreement with the longitudinal direction of the attachment unit. A
compromise between these demands causes a weak or completely
dissatisfactory attachment in the jaw bone or that the tooth
prothesis will be wrongly directed.
Therefore, there is a need for an attachment means of the kind
indicated above, in which the part, growing together with the jaw
bone, may form an angle with the part, to which the prothesis
should be attached.
The present invention refers to an arrangement in attachment means
of the above indicated kind, by which said need is satisfied.
According to the invention, there is provided between the part of
the attachment means intended to grow together with the skeleton
tissue, on the one hand, and the part of the attachment means,
which shall carry up the prothesis, on the other side, a ball joint
like arrangement, comprising at least one joint but perhaps two or
more joints.
Further details of the invention will be apparent from the
following description in connection with the attachmed drawings,
showing a number of different forms of execution of the invention.
However, it is understood that the invention shall not be limited
to one or more or all of these forms of execution, but that all
different kinds of modifications or combinations between the
different forms of execution may be made within the frame of the
invention.
In the drawings,
FIG. 1 shows an arrangement according to the invention, in which
only one single gall joint appears, and in which the ball is
applied on the part of the attachment means intended to grow into
the bone tissue, whereas the ball claw cooperating with the ball is
applied on the part to which the prosthetic structure is intended
to be attached.
FIG. 2 shows an arrangement in which the two means contained in the
ball joint are applied in the opposite way, and
FIG. 3 shows the same arrangement as in FIG. 2, but doubled so that
there are two ball joints in cascade. In all of the said three
forms of execution there is a ball claw for clamping the ball.
FIG. 4, however, shows an arrangement in which the ball claw has
been replaced by a stretch joint arrangement, running through part
of the contact surface of the ball joint, and
FIG. 5 shows the corresponding arrangement with a spherical
ball.
FIGS. 6 and 7 show a variation of the arrangement according to FIG.
2.
In the arrangement according to FIG. 1 the part growing together
with the jawbone comprises a bolt formed part 10, which is provided
with outside threads for screwing the same into a hole drilled in
the jawbone and provided with inside threads. The part 10 further
is provided with a well 11 entering from below, which communicates
through radially directed openings 12 with the outside of the part
10 which is provided with the threads 13. The holes are intended
for making it possible for bone tissue to grow in, in connection
with the part 10 growing together with the bone tissue. At the
upper end the part 10 is provided with a flange 14, having an
L-formed section for the reception of a free collar 15, which
forms, on its inner side, the socket for reception of the ball 16
in the above mentioned ball joint. Hereinafter, the term "socket"
shall be understood as any means for retaining a ball in its
position contained in the ball joint, independently of whether this
part is cup-formed or perhaps for instance claw-formed. However, it
may happen that a separate ball claw is applied between the ball
and the socket. This ball claw initially is open, but is staved
after the introduction of the ball, so that it will permanently
embrace the ball. The ball claw may be cut up or closed all
around.
The ball 16 is attached to a shaft 17, which is provided at its
lower end with threads and is screwed into the bolt-formed part 10,
said part for this purpose being provided with a well 18 having
inside threads. Between the concave part of the collar 15 forming
the socket, and the convex spherical part of the ball 16, a ball
claw 19 is placed, which is attached to the upper part 20 of the
attachment means. This part 20 is built up in such a way that it
will give a good fixture for the prosthetic structure 21, but this
detail does not form the subject of the present invention per se,
and it will therefore also not be further described here. The upper
part 20, however, is drilled through with a hole 22, running in the
axial direction and inwardly threaded, in the threads of which it
is possible to screw in a bolt 23 along with an arrangement for
moving bolt 23 axially, for instance a screw driver groove 24. In
FIG. 1 the screw driver groove and the parts of the cavity within
the part 20 adjacent the groove 24 have been shown to be filled
with cement, amalgame or any similar filler mass. The bolt 23, at
its lower end, is provided with a preferably conical cavity 25
having such a top angle that, when the bolt is drawn in, the edges
of the cavity will mesh with the ball 16 and lock this against
mutual movement between the ball 16 and the upper part 20 of the
attachment means.
When an attachment means of the kind described above is to be
attached to the jawbone of a patient, requiring a permanently
implanted prosthetic structure 21, the dental surgeon acts so that
he will first drill, and if required provide threads in the opening
in the jawbone for the lower part 10 of the attachment means.
Thereby he can determine the axial direction of the opening so that
this opening in the jawbone will in the best possible way be
centered in the jawbone, and so that it will not get in the
immediate vicinity of the surface parts of the jaw bone. In many a
case, however, because of the form of the jaw bone the drilled hole
runs in a direction, the axis of which forms an angle with the
direction which the upper part 20 of the attachment means must
assume basis of the form for proper alignment of the prosthetic
structure. In the drilled and threaded hole thereafter the dental
surgeon screws in the lower part 10 of the attachment means, after
which he puts a temporary sealing arrangement of some suitable kind
in the mouth of the patient and perhaps also on the threaded hole
18 in the lower part 10, and he folds over the weak tissue, folded
away at the earlier treatment, in order to heal this, and also to
heal the damages caused in the jawbone. Simultaneously the lower
part 10 is allowed to grow together with the bone tissue or other
hard tissue growing together with the outer surface of the lower
part 10, which has for this purpose been rifled or in any other
suitable way made uneven. Further, bone tissue will grow into the
hole 12. Screwing up the lower part 10 thereafter is effectively
prevented.
The lower part 10 thereafter is left in the way mentioned above to
grow together with the jawbone, which usually will take
approximately six weeks. After healing is completed, the dental
surgeon again cuts up the weak tissue over the lower part 10, which
has now been healed, and he uncovers the lower part, screwed into
the threaded hole 18, along with its cover screw by folding away
and/or operating away skin and gums and he removes the cover screw
and screws in the bolt 17 along with the ball, after having applied
the collar 15 in its place. At this time the part 20 and the bolt
17 assume a straight line and are locked in this position by means
of the screw 22. When the bolt 17 is completely screwed into the
hole 18 so that the part 19 is in contact with the socket 15 the
screw 20 is slightly released and the part 20 is turned to the
desired direction. After the part 20 has thus been placed in the
correct direction, is again locked in this position by means of the
screw 22, so that it cannot be moved any further. When all
attachments are mounted according to the above, the dentist makes a
print, and guided by this the tooth technician thereafter makes a
prosthetic structure, which may be cemented to the part 20.
In this connection it should be observed that the attachment means
according to the present invention may, of course, be used for
attachment of a prosthetic structure in the lower jaw as well as
for attachment of a prosthetic structure in the upper jaw.
Hereinafter the terms "lower" and an "upper" part refer to the use
of the attachment means for attachment of a prosthetic structure to
the lower jaw. Normally, for a complete prosthesis, a plurality of
such attachment means are required, but it will be apparent to the
dental surgeon in any specific case how the prosthetic structure
should be distributed along the jawbone in order to give a
satisfactory attachment. For that reason only one single attachment
means is shown in the drawings. Of course, the same attachment
means may be used for attachment of a prosthetic structure,
representing a single tooth.
FIG. 2 shows a variation of the arrangement according to FIG. 1.
The lower part 27 of the attachment means has been shown here only
schematically. One may directly screw this lower part into the
drilled and threaded hole in the jawbone, but it is also possible
to let the lower part 27 replace the bolt 18 in the arrangement
according to FIG. 1. The essential difference between the
arrangements according to FIG. 1 and FIG. 2 concerns the
arrangement of the ball joint.
In the arrangement according to FIG. 2 the ball claw 28 is provided
in a direction upwardly and made in one piece with the lower part
27. It encloses in itself a ball 29, which is oval in
cross-section, said ball being provided with a threaded hole 30 for
reception of a downwardly directed pin 31, made in the same piece
as the attachment pin 32 for the prosthetic structure 33. By the
pin 31 being threaded on its outside for threadedly engaging the
inwardly threaded hole through the ball 29, all of the ball joint
may be locked in its adjusted position by turning all of the pin
construction 31 - 32, whereby the ball claw 28 is clamped between
the ball 29 and the socket 15.
The attachment of the prosthetic structure 33 may in the
arrangement according to FIG. 2 take place in the same way as
already described in connection with FIG. 1, but it may also take
place in such a way that a screw 34 is screwed down through the
prosthetic structure 33 and into a threaded hole 35 in the pin
32.
FIG. 3 shows a modification of the arrangement according to FIG. 2,
in which one has provided for the possibility that a parallel
displacement must take place between the lower and the upper part
of the attachment means, perhaps in connection with a change of
direction. This makes it necessary have two ball joints, which have
been shown in FIG. 3 to each of which would be made in the same way
as the single ball joint according to FIG. 2 the two ball joints
being interconnected by a central part 32'. For this reason also
the same reference numerals have been used, however the numerals
for the lower ball joint are provided with a prime and the numerals
of upper ball joint are provided with a double prime.
The locking of the ball joint need not necessarily take place by
means of a locking bolt of the type shown in the earlier forms of
execution, but it may also advantageously take place by means of a
thread, a wire or the like. In this way the ball claw 19 or 28,
resp., according to the FIGS. 1 - 3 may be avoided. An arrangement
of the last mentioned type is shown in FIG. 4.
In this case, therefore, no such ball claw as shown in FIG. 1 at 19
and in FIGS. 2 and 3 at 28 required, because in place thereof a
thread formed means, for instance a wire 36 has been provided. The
ball is attached in FIG. 4 to the upper end of the lower part 27 of
the attachment means and forms there a semi-spherical calotte with
a rather wide recess 37, which should preferably be close to or
completely frustro-conical. From the bottom of the recess 37 a well
38 is drilled in a direction downwardly into the lower part 27 of
the attachment means. This well suitably is provided with threads
for attachment of a plug 39 with a central bore, through which the
wire 36 runs under such circumstances that it will be retained in a
given position against drawing, when the plug is screwed into the
well. The socket 40 cooperating with the ball 16 is in this case
formed at the lower end of the upper part of the attachment means
20, and also this concave calotte surface is provided with a recess
for the wire 36, so that it may run in stretched state through both
of these recesses, even if there should exist an essential angular
difference between the lower part 27 and the upper part 20 of the
attachment means.
In the upper part 20 of the attachment means there is provided some
suitable arrangement for stretching the wire 36, after the upper
attachment means part 20 has been placed in correct angular
position in relation to the lower attachment means part 27. This
stretching device may, as shown in FIG. 4, comprise a piston 41
threaded into a bore in the part 20 running quite through it and
provided with internal threads, and further being provided with a
hole for the attachment of the wire 36, which is widened at its
upper part in the form of an inwardly threaded well 42. The wire is
attached to the hole, so that it is stretched, when the piston 41
is screwed upwardly. The attachment of the prosthetic structure 48
may suitably take place by means of a sleeve 45.
Another form of the arrangement according to FIG. 4 is shown in
FIG. 5. In this case the ball 49 is not mechanically combined with
the lower part of the attachment means, nor with the upper part
thereof. It is spherical, but it contains two conical recesses
opposing each other and meeting in the center part of the ball. The
conical recesses 50 and 51 have, at the place of meeting, such a
width that the wire 36 may pass through the ball. The wire 36, as
earlier described, is stretched at both ends. Thus, a conventional
wire lock 52 is provided in the interior of the lower part 27 of
the attachment means. This wire lock comprises two cup-formed parts
53, 54, directed in opposite direction directions with respect to
the open, interior parts thereof, said parts being inwardly
provided with hooks for attachment with the surface of the wire,
and outwardly they are conical in order to be pressed together by
pressure from the inwardly conical wall of the hole through the
lower part 27 of the attachment means. A screw spring 55 spans the
space between a washer 56 and the lower surface of the two cups 53,
54 in order to press them upwardly into the narrower part of the
conical hole in the lower part 27. At its upper end the wire is
attached to the piston 41 by means of a hole in this, which is also
conical, and in which the end of the wire 36 is mounted after
having been widened by means of a wedge 57. The part 41, as was the
case in the arrangement according to FIG. 4, is screwed into an
inwardly threaded hole in the upper part 40 of the attachment
means, which carries the prosthetic structure 48.
In the arrangement according to FIG. 6 the ball is substantially
semi-spherically formed. The ball 64 is provided with a downwardly
directed pin 65, forming the seat of a screw spring 66, the other
end of which rests on the bottom, which is in this case completely
spherical, of the recess within the ball claw 28. In other respects
the arrangement is in essential parts made in the same way as the
arrangement according to FIG. 2, and parts corresponding to each
other have therefore also been provided with same reference
numerals. By means of the screw spring 66 the ball 64 is pressed
upwardly onto the ball claw 28, so that by friction between these
two parts the ball 64 will be prevented from rotating to turn the
screw connected to the part 59.
It may also happen that the dental surgeon during his work with the
attachment means will have to turn certain parts while other parts
should not be turned. This especially concerns screwing in the
threaded parts. For this purpose there is provided an outer
six-edged profile 67 on the part 58.
A further six-edge profile 68 is provided on the lower part 27 as
seen from the arrangement according to FIG. 7, which is not shown
in section. In other parts this is similarily shaped as the
arrangement according to FIG. 6. The last mentioned six-edge
profile is intended to be used when screwing the lower part 27 into
the jawbone.
* * * * *