U.S. patent application number 09/729077 was filed with the patent office on 2001-06-28 for blind rivet with fastener.
Invention is credited to Frigg, Robert.
Application Number | 20010005475 09/729077 |
Document ID | / |
Family ID | 4551333 |
Filed Date | 2001-06-28 |
United States Patent
Application |
20010005475 |
Kind Code |
A1 |
Frigg, Robert |
June 28, 2001 |
Blind rivet with fastener
Abstract
The present invention relates to an orthopedic fastener for
fixing an implant, suture, or tissue to a bone. The fastener
comprises a blind rivet and a closing element. The blind rivet
includes a head at a proximal end, a shank connected to the head,
and an anchoring portion near a distal end. A bore extends through
the head and shank from the proximal end to the distal end and the
bore has a polygonal cross-section through the anchoring portion.
The closing element has a body with an outer surface and is
configured and dimensioned to be received in the anchoring portion.
The outer surface of at least a portion of the closing element
distal end has a polygonal cross-section flaring along the
longitudinal axis toward the closing element distal end. The
anchoring portion of the blind rivet severs into a plurality of
anchoring legs when the closing element is pulled in the bore
toward the blind rivet proximal end to thereby prevent rotation of
the fastener.
Inventors: |
Frigg, Robert; (Bettlach,
CH) |
Correspondence
Address: |
PENNIE & EDMONDS LLP
1667 K STREET NW
SUITE 1000
WASHINGTON
DC
20006
|
Family ID: |
4551333 |
Appl. No.: |
09/729077 |
Filed: |
December 4, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09729077 |
Dec 4, 2000 |
|
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PCT/CH99/00194 |
May 11, 1999 |
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Current U.S.
Class: |
411/501 ;
606/60 |
Current CPC
Class: |
A61B 17/0401 20130101;
A61F 2002/30154 20130101; A61F 2002/0858 20130101; A61F 2002/0888
20130101; A61F 2002/30433 20130101; A61F 2002/0882 20130101; A61F
2220/0041 20130101; A61F 2/3676 20130101; A61F 2230/0021 20130101;
F16B 19/1054 20130101; A61F 2/0811 20130101; A61F 2002/3694
20130101; A61F 2002/30594 20130101; A61F 2002/30579 20130101; A61B
17/68 20130101; A61B 2017/0408 20130101; A61B 2090/037
20160201 |
Class at
Publication: |
411/501 ;
606/60 |
International
Class: |
F16B 019/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 4, 1998 |
CH |
PCT/CH98/00242 |
Claims
What is claimed is:
1. An orthopedic fastener for fixing an implant, suture, or tissue
to a bone, the fastener having a longitudinal axis and comprising:
a blind rivet with proximal and distal ends and having a head at
the proximal end, a shank connected to the head and including an
outer diameter and an anchoring portion near the distal end, and a
bore extending through the head and shank from the proximal end to
the distal end, the bore having a polygonal cross-section through
the anchoring portion; and a closing element having proximal and
distal ends and a body with an outer surface and configured and
dimensioned to be received in the anchoring portion, the outer
surface of at least a portion of the closing element distal end has
a polygonal cross-section flaring along the longitudinal axis
toward the closing element distal end, wherein the anchoring
portion of the blind rivet severs into a plurality of anchoring
legs when the closing element is pulled in the bore toward the
blind rivet proximal end to thereby prevent rotation of the
fastener.
2. The fastener of claim 1 wherein the polygonal cross-section of
the bore includes a plurality of corners that form rupture sites
between the corner and the outer diameter of the shank to
facilitate severing of the anchoring portion into the anchoring
legs.
3. The fastener of claim 2 wherein the rupture sites have a wall
thickness between about 1% and 9% of the outside diameter of the
shank.
4. The fastener of claim 1 wherein the closing element distal end
has a conical cross-section.
5. The fastener of claim 1 wherein the closing element is part of a
marrow spindle.
6. The fastener of claim 1 wherein the head of the blind rivet is
integral with the shank.
7. The fastener of claim 1 wherein the head of the blind rivet is
detachable from the shank.
8. The fastener of claim 7 wherein the rivet head includes an
inside thread and the shank includes a matching outside thread for
detachable coupling of the head and shank.
9. The fastener of claim 1 wherein distal end of the closing
element has a tip for facilitating insertion of the closing element
in bone.
10. The fastener of claim 1 wherein at least a portion of the bore
is threaded for threadably receiving an implant.
11. The fastener of claim 1 wherein the anchoring portion has a
wall thickness that is between about 1% and 20% of the outer
diameter of the shank.
12. The fastener of claim 11 wherein the distal end has a wall
thickness that is greater than that of the proximal end of the
blind rivet.
13. The fastener of claim 1 wherein two mutually opposite ends of
two mutually opposite anchoring legs of the closing element subtend
a distance two to three times the outer diameter of the shank.
14. The fastener of claim 1 further comprising a closing pin
operatively associated with the closing element and having a first
end extending through the bore to pull the closing element through
the blind rivet toward the proximal end.
15. The fastener of claim 14 wherein the closing element is
detachably connected to the closing pin.
16. The fastener of claim 15 wherein the closing pin is connected
to the closing element by a design rupture site which allows the
closing pin to separate from the closing element.
17. The fastener of claim 15 wherein the proximal end of the
closing element includes a thread and an end of the closing pin
includes a matching thread.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of the U.S. National
Stage designation of co-pending International Patent Application
PCT/CH99/00194, filed on May 11, 1999, which claims priority to
International Patent Application PCT/CH98/00242, filed Jun. 4,
1998. The entire content of both these applications is expressly
incorporated herein by reference thereto.
FIELD OF THE INVENTION
[0002] The present invention relates to a device for attaching a
suture, tissue, or implant to a bone.
BACKGROUND OF THE INVENTION
[0003] The use of blind rivets in non-medical fields is wide
spread. Such blind rivets, which typically have a closing head
consisting of separate and comparatively widely spread legs, are
known for example from U.S. Pat. No. 4,696,610 to Wright and U.S.
Pat. No. 4,580,936 to Francis. These known blind rivets have
longitudinal slits or cuts near the end of the shaft which form the
closing head when the blind rivet is closed. The closing heads so
formed rest on a large area. These known blind rivets incur the
drawback that the closing heads are formed by bending the
longitudinal legs and, as a result, the leg ends are not sharp
tines and cannot be pressed into the material to which the rivet is
being attached. Thus, these types of blind rivets do not prevent
the blind rivet from rotating in the boreholes of the materials to
be connected.
[0004] A different non-medical blind rivet is known from British
Application No. 2,054,082 of Tucker Fasteners. This fastener
includes a pyramidal shaped head that passes through a cylindrical
bore.
[0005] Other fasteners operate in a manner analogous to a blind
rivet. Examples of these fasteners include screws, marrow pins, and
hip screws. The Seidel marrow pin for the humerus is fitted with
slits at the tip and the slits are spread apart by a central pin
with a ballhead. In this manner, the legs are bent outward like
wings. However, these legs are bent only slightly away from the
nail. Use of these fasteners to anchor an implant in porotic bone
is problematic. Often an implant can be affixed to such bone only
by injecting bone cement into the bone. This procedure can further
damage a bone due to heat necrosis as the cement hardens. Moreover,
the cement no longer can be removed as would be required in case of
infection.
[0006] Another drawback of these known fasteners is that the
anchoring strength is determined by its diameter. If there is axial
overload, a cylinder of bone equal to the fastener diameter will be
torn out. In healthy bone, the anchoring strength of bone screws
will be sufficient. But in the case of osteoporosis, in joint
zones, or as regards thin, shell-like bones, screw affixation often
will be inadequate. Larger screws cannot be used because of lack of
space, or else they destroy the remaining bone even more.
[0007] Thus, there exists a need for an improved fastener.
SUMMARY OF THE INVENTION
[0008] The present invention relates to an orthopedic fastener for
fixing an implant, suture, or tissue to a bone. The fastener
comprises a blind rivet and a closing element. The blind rivet
includes a head at a proximal end, a shank connected to the head,
and an anchoring portion near a distal end. A bore extends through
the head and shank from the proximal end to the distal end and the
bore has a polygonal cross-section through the anchoring portion.
The closing element has a body with an outer surface and is
configured and dimensioned to be received in the anchoring portion.
The outer surface of at least a portion of the closing element
distal end has a polygonal cross-section flaring along the
longitudinal axis toward the closing element distal end. The
anchoring portion of the blind rivet severs into a plurality of
anchoring legs when the closing element is pulled in the bore
toward the blind rivet proximal end to thereby prevent rotation of
the fastener.
[0009] The anchoring legs can be spread by the closing elements
into a semi-circular shape relative to the longitudinal axis to
thereby form the closing head of the blind rivet. This feature
provides a broad rest for instance on the inside bone surface and,
because the semi-circular shape of the anchoring leg ends rest
almost perpendicularly on the bone surface, this design offers
jaw-like anchoring the closing head. The blind rivet can be made of
a plastically deforming material, such as pure titanium, a titanium
alloy, or implant-steel, to enhance the formation of the
semi-circular anchoring legs.
[0010] In another embodiment of the fastener of the invention, two
mutually opposite ends of two mutually opposite anchoring legs of
the closing element subtend a distance "L" which is two to three
times the blind rivet's diameter "D". Again this considerable
widening of the anchoring legs provides a broad rest on the inside
bone surface.
[0011] The polygonal cross-section of the bore can include a
plurality of corners that form rupture sites between the corner and
the outer diameter of the shank to facilitate severing of the
anchoring portion into the anchoring legs. In an exemplary
embodiment, the rupture sites have a wall thickness between about
1% and 9% of the outside diameter of the shank.
[0012] The head of the blind rivet can be integral with the shank.
Alternatively, the head of the blind rivet is detachable from the
shank. If detachable, the rivet head can include an inside thread
and the shank includes a matching outside thread for detachable
coupling of the head and shank.
[0013] The closing element distal end can have a conical
cross-section. The distal end of the closing element can also have
a tip (like a gimlet or awl) for facilitating insertion of the
closing element in bone. In order to facilitate severing, the
anchoring portion can have a wall thickness that is between about
1% and 20% of the outer diameter of the shank. This design allows
spreading the rivet shank in simple manner into the separate
anchoring elements by means of the polygonal cone at the closing
element. In one embodiment, the distal end has a wall thickness
that is greater than that of the proximal end of the blind
rivet.
[0014] In an exemplary embodiment, the fastener includes a closing
pin operatively associated with the closing element. The closing
pin has a first end extending through the bore to pull the closing
element through the blind rivet toward the proximal end. The
closing element can be detachably connected to the closing pin. For
example, the closing pin can be connected to the closing element by
a design rupture site which allows the closing pin to separate from
the closing element. Alternatively, the proximal end of the closing
element includes a thread and an end of the closing pin includes a
matching thread.
[0015] The fastener according to the present invention results in
palliation. In use, the fastener is insertable through a small
borehole and, following affixation, includes a broad resting
surface on the inner bone surface due to the spread out anchoring
legs. These anchoring legs can dig into the inner bone surface and
thereby prevent the blind rivet from rotating.
[0016] One advantage offered by the present invention is that the
fastener of the invention requires only a small borehole in the
bone. However, after implantation, the blind rivet of the invention
broadly rests on the inner bone surface. Moreover and
illustratively in a manner different from the case relating to a
hip screw, the semicircular anchor-like design of the anchoring
legs and their anchoring in the bone preclude rotation by the
fastener head. With respect to porotic bones, the spongiosa in
joint heads--if still present at all--will not be mechanically
stressed. In other words, the hip screw is situated in a cavity,
and this feature entails a dislocation of the hip head relative to
the hip screw. The hip screw only can become functional after it
makes contact with the inner bone surface. In such cases, however,
the interface between screw and bone often is inadequate, so that
the bone screw may penetrate the hip joint. In the invention on the
other hand, the inner head surface is used as the interface between
implant and bone when using the blind rivet of the invention with
the semi-circular anchoring legs. In this manner, the surface of
contact with the bone is larger and matches optimally on account of
the anatomically matching anchoring legs. If the blind rivet of the
invention is used to anchor a marrow spindle into the femur head,
the size of the borehole receiving the blind rivet of the invention
will only be about 8 mm. This feature offers the advantage that in
comparison with conventional systems of marrow-spindles/hip-screws,
the diameter of the marrow spindle can be substantially reduced in
the application of the invention.
[0017] In the medical field, the fastener of the invention is
applicable almost universally in the treatment of bone fractures
for which a bone screw or similar fastener is presently used.
Specifically:
[0018] for porotic bones partly comprising only a very thin cortex,
the fastener of the invention can replace screws in fastening
plates;
[0019] in the spongiosa, the fastener of the invention can serve as
an anchor for plates, sutures or to reattach tendons and ligaments
(the claws formed when spreading the closing head will anchor well
into the trabecular structure of the spongiosa); and
[0020] in joint heads such as the femur head or the humerus head,
the fastener of the invention can be used as the anchor of a side
plate or of an intramedullary support (heretofore large screws have
been used to anchor the longitudinal supports, however these screws
anchor less than optimally in the joint heads' porotic bones).
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 shows a longitudinal section of an embodiment of a
fastener according to the present invention;
[0022] FIG. 2 shows a longitudinal section of a fastener according
to the present invention with a closing element that differs from
that of FIG. 1;
[0023] FIG. 3 is a cross-section taken along line A-A of FIG.
2;
[0024] FIG. 4 is a longitudinal section of a fastener with a closed
blind rivet fixing a bone plate to a bone;
[0025] FIG. 5 is an elevation of the embodiment of the closed blind
rivet shown in FIG. 4;
[0026] FIG. 6 is a longitudinal section of another embodiment of
the blind rivet component of the fastener according to the present
invention;
[0027] FIG. 7 is a front view of the blind rivet shown in FIG.
6;
[0028] FIG. 8 is a longitudinal section of another embodiment of
the blind rivet component of the fastener according to the present
invention;
[0029] FIG. 9 is a longitudinal section of another embodiment of
the fastener according to the present invention;
[0030] FIG. 10 is a front view of the fastener of FIG. 9; and
[0031] FIG. 11 is a longitudinal section of a femur bone with a
marrow spindle, assembly sleeve, and a blind rivet according to the
present invention.
DETAILED DESCRIPTION OF DRAWINGS
[0032] FIG. 1 shows one embodiment of the fastener according to the
present invention. The fastener includes a blind rivet 1 and a
closing element 2. Blind rivet 1 has a longitudinal axis 3 and
consists of a cylindrical rivet shank 8 that runs parallel to
longitudinal axis 3 and a rivet head 19 rigidly joined to rivet
shank 8. A cylindrical passage (i.e., a bore) 4 passes coaxially
through blind rivet 1. Rivet shank 8 is of diameter "D" and, as a
result, the wall thickness "s", defined by the width of passage 4
and the outside diameter "D", is such that when closing blind rivet
1 by means of closing element 2, the blind rivet can be severed at
the closing part or anchoring part 9 into anchoring legs 13 (FIG. 4
and FIG. 5). The number of anchoring legs 13 corresponds to the
number of edges of the polygonal cross-section 5 of closing element
2 (FIG. 3). In this particular embodiment of blind rivet 1, wall
thickness "s" of rivet shank 8 amounts to 14% of the outer diameter
"D".
[0033] In the embodiment of the fastener of the invention shown in
FIG. 1, closing element 2 is a component of a closing pin 16. At
the segment adjoining rear end 12, closing element 2 is of
polygonal cross-section 5 (FIG. 3) flaring toward rear end 12.
Blind rivet 1 will be closed following insertion of closing element
2 which, by tension applied to closing pin 16, is pressed into
closing part 9 of blind rivet 1. When flaring segment 7 is pressed
inward, the wall of rivet shank 8 is widened by segment 7 of
closing element 2 and is severed by the edges of polygonal
cross-section 5 into anchoring legs 13. The conical angle being
selected in such manner that both severing of the rivet shank into
separate anchoring legs and widening of the anchoring legs when
closing the blind rivet will be enhanced. Closing pin 16 can be
connected by a design rupture site to closing element 2 to allow
separating this pin from this closing element after closing blind
rivet 1, for instance by applying twisting forces.
[0034] The embodiment of the fastener according to the present
invention shown in FIG. 2 differs from the embodiment of FIG. 1 in
that closing element 2 is fitted with an inside thread 24 coaxial
with longitudinal axis 3 and closing pin 17 is fitted with a
matching outside thread 23 to allow detachably screwing closing pin
17--which is a separate part--into closing element 2. Following
closure of blind rivet 1, closing pin 17 can be screwed out of
closing element 2 and thereby be removed from closed blind rivet
1.
[0035] FIG. 3 is a section perpendicular to the longitudinal axis
of the closing element 2. In this embodiment, the polygonal
cross-section 5 is a square 6 forming four anchoring legs 13 when
closing blind rivet 1. FIG. 3 also shows inside thread 24 of
closing element 2 of the fastener of the invention embodiment of
FIG. 2.
[0036] FIG. 4 shows a longitudinal section of a closed blind rivet
1 of another embodiment of the invention. Blind rivet 1 connects a
bone plate 25 to a bone 26. Cosing head 14 comprises four anchoring
legs 13, of which ends 31 subtend the distance "L". FIG. 4 also
shows that the distance "L" subtended by ends 31 of anchoring legs
13 is approximately triple the diameter "D" of rivet shank 8. FIG.
5 shows an elevation of the closed blind rivet 1 of FIG. 4 with
four anchoring legs 13.
[0037] The blind rivet 1 shown in FIG. 6 and FIG. 7 of another
embodiment of the fastener of the invention differs from the
embodiment of FIG. 1 in that bore 4 has a square cross section at
closing part 9 of blind rivet 1. One advantage of a cross-section
of few polygonal edges is that the edges are more sharply defined
and severing the rivet shank into separate anchoring legs and
widening these legs when closing the blind rivet is thus enhanced.
Corners 15 of bore 4 form design rupture sites between this passage
and the outside diameter "D" of rivet shank 8 to facilitate
severing of shank 8 into anchoring legs 13 when blind rivet 1 is
being closed. Advantageously, the rupturing sites wall thickness
can be between 1% and 10%, and preferably between 5% and 9%, of the
outside diameter "D" of the blind rivet. At the segment of the
blind rivet 1 adjoining rivet head 19, bore 4 is fitted with an
inside thread 22 coaxial with longitudinal axis 3.
[0038] The embodiment shown in FIG. 8 has a blind rivet 1 with a
rivet head 20 that is detachably connected to rivet shank 8. This
detachable connection of rivet head 20 and rivet shank 8 can be
implemented by threads. Accordingly, river shank 8 is fitted with
an outside thread 27 coaxial with longitudinal axis 3 and rivet
head 20 is fitted with a matching inside thread 28.
[0039] FIG. 9 and FIG. 10 show a further embodiment of the fastener
according to the present invention. Blind rivet 1 does not have a
rivet head and consists of a cylindrical rivet shank 8 having a
longitudinal axis 3 and a bore 4 also coaxial with axis 3. If the
blind rivet is used as an anchor, for instance as a fastener in the
femur head, together with a side plate or a marrow spindle or a
suture anchor, an embodiment of the blind rivet without a rivet
head will be appropriate. The design of a headless blind rivet
offers the advantage of deeper bone penetration during spreading.
This "post-slippage" prevents cutting the spongiosa when the blind
rivet is being spread apart. Closing element 2 is fitted with an
awl 21. The diameter "d" of awl 21 corresponds to the outside
diameter "D" of the blind rivet 1 and thereby pre-drilling bone 26
(FIG. 4) is not needed when assembling blind rivet 1. A gimlet can
be used instead of awl 21.
[0040] FIG. 11 shows an application of blind rivet 1 to lock a
marrow spindle 18 (for instance in a femur bone 29). Marrow spindle
18 is secured axially in the proximal direction by inserting blind
rivet 1. Closing element 2 is mounted as a component of marrow
spindle 18 at its distal end 32. To assemble blind rivet 1, it is
clamped between closing element 2 and a case 30 and is inserted
together with the marrow spindle 18 into the femur bone 29. By
tensioning marrow spindle 18 in the proximal direction and applying
an opposite retention force to case 30, closing head 14 is shaped
at blind rivet 1, which thereby is locked.
[0041] The preferred embodiments disclosed above discuss the
present invention using specific orthopedic procedures; however,
the blind rivet can be used almost universally in the treatment of
bone fractures where presently bone screws are used. While it is
apparent that the illustrative embodiments of the invention herein
disclosed fulfil the objectives stated above, it will be
appreciated that numerous modifications and other embodiments may
be devised by those skilled in the art. Therefore, it will be
understood that the appended claims are intended to cover all such
modifications and embodiments which come within the scope of the
present invention.
* * * * *