U.S. patent application number 14/482073 was filed with the patent office on 2014-12-25 for soft tissue attachment device.
The applicant listed for this patent is MAYO FOUNDATION FOR MEDICAL EDUCATION AND RESEARCH. Invention is credited to DAVID G. LEWALLEN.
Application Number | 20140379008 14/482073 |
Document ID | / |
Family ID | 42132341 |
Filed Date | 2014-12-25 |
United States Patent
Application |
20140379008 |
Kind Code |
A1 |
LEWALLEN; DAVID G. |
December 25, 2014 |
SOFT TISSUE ATTACHMENT DEVICE
Abstract
Methods and devices are disclosed for the attachment of a soft
tissue structure (e.g., tendon or ligament) to bone or a prosthetic
implant. In one form, the device includes a clamp having a convex
tissue engaging surface. A fastener compresses the soft tissue
between the tissue engaging surface and the bone or the prosthetic
implant. In another form, the device includes a second clamp
comprising a porous metallic material. The second clamp has a first
surface, a concave tissue engaging surface opposite the first
surface, and a throughhole for a fastener. The second clamp is
placed adjacent the bone, the soft tissue is placed adjacent the
second clamp, and the first clamp is placed adjacent the soft
tissue. The soft tissue is compressed between the convex tissue
engaging surface of the first clamp and the concave tissue engaging
surface of the second clamp using the fastener.
Inventors: |
LEWALLEN; DAVID G.;
(Rochester, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAYO FOUNDATION FOR MEDICAL EDUCATION AND RESEARCH |
ROCHESTER |
MN |
US |
|
|
Family ID: |
42132341 |
Appl. No.: |
14/482073 |
Filed: |
September 10, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12612205 |
Nov 4, 2009 |
8858634 |
|
|
14482073 |
|
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Current U.S.
Class: |
606/151 |
Current CPC
Class: |
A61F 2/0811 20130101;
A61F 2002/0888 20130101; A61F 2002/0829 20130101; A61F 2002/0858
20130101; A61F 2002/0864 20130101 |
Class at
Publication: |
606/151 |
International
Class: |
A61F 2/08 20060101
A61F002/08 |
Claims
1. A device for attaching soft tissue to a single bone, or to first
and second bones, or to a single prosthetic implant, or to first
and second prosthetic implants, the device comprising: a first
attachment device including a first clamp comprising a porous
metallic material, the first clamp including a first surface, a
convex tissue engaging surface opposite the first surface, and a
throughhole extending from the first surface to the convex tissue
engaging surface; a fastener dimensioned for placement in the
throughhole of the first clamp, the fastener being dimensioned to
engage a surface of the first clamp, the soft tissue and the single
bone, the first bone, the single prosthetic implant, or the first
prosthetic implant such that the soft tissue is compressed between
the tissue engaging surface and the single bone, the first bone,
the single prosthetic implant, or the first prosthetic implant; and
a second attachment device including a first part comprising a
porous metallic material and a mating second part comprising a
porous metallic material, wherein the soft tissue is compressed
between the first part and the second part.
2. The device of claim 1 wherein: the convex tissue engaging
surface of the first clamp has a first curvature, the single bone,
the first bone, the single prosthetic implant, or the first
prosthetic implant includes a depression of a second curvature, the
first clamp is adapted to compress the soft tissue between the
tissue engaging surface of the first clamp and a concave surface of
the depression of the single bone, the first bone, the single
prosthetic implant, or the first prosthetic implant, and the first
curvature is greater than the second curvature.
3. The device of claim 1 further comprising: a grommet arranged in
the throughhole.
4. The device of claim 1 wherein: the convex tissue engaging
surface includes a raised section around the throughhole.
5. The device of claim 1 wherein: the first clamp includes a
periphery having a shape selected from circular, rectangular,
elliptical and oval.
6. The device of claim 1 wherein: the first clamp includes a second
throughhole for receiving a second fastener.
7. The device of claim 1 wherein: the first part comprises a first
channel, the second part comprises a second channel, and the soft
tissue is compressed between an inner surface of the first channel
of the first part and an inner surface of the second channel of the
second part.
8. The device of claim 7 wherein: the first part and the second
part form a frustoconical shape when mated together.
9. The device of claim 1 wherein: the porous metallic material of
the first clamp comprises titanium, the porous metallic material of
the first part comprises titanium, and the porous metallic material
of the second part comprises titanium.
10. The device of claim 1 wherein: the convex tissue engaging
surface of the first clamp is dome shaped.
11. The device of claim 1 wherein: the device is for attaching soft
tissue to first and second bones, the first bone being the tibia,
and the second bone being the femur.
12. The device of claim 11 wherein: the second attachment device is
dimensioned to be received in a tunnel in the femur.
13. The device of claim 12 wherein: the second attachment device is
dimensioned to be wedged in the tunnel in the femur.
14. The device of claim 11 wherein: the first part includes a first
semicircular end and a second semicircular end of greater radius
than the first semicircular end, and the second part includes a
first semicircular end and a second semicircular end of greater
radius than the first semicircular end.
15. The device of claim 11 wherein: the convex tissue engaging
surface of the first clamp has a first curvature, the tibia
includes a depression of a second curvature, the first clamp is
adapted to compress the soft tissue between the tissue engaging
surface of the first clamp and a concave surface of the depression
of the tibia, and the first curvature is greater than the second
curvature.
16. The device of claim 11 wherein: the first clamp is configured
such that a gap between the tissue engaging surface of the first
clamp and the concave surface of the depression of the tibia is
bigger near a periphery of the first clamp and smaller centrally
near the fastener when the soft tissue is compressed between the
tissue engaging surface and the tibia.
17. The device of claim 1 further comprising: a second clamp
comprising a porous metallic material, the second clamp including a
first surface and a concave tissue engaging surface opposite the
first surface, wherein the second clamp is adapted to be received
in a depression in the single bone, the first bone, the single
prosthetic implant, or the first prosthetic implant, and wherein
the first clamp is adapted to compress the soft tissue between the
tissue engaging surface of the first clamp and the tissue engaging
surface of the second clamp.
18. A method for attaching soft tissue to a tibia and a femur, the
method comprising: placing soft tissue adjacent the tibia; placing
a first clamp comprising a porous metallic material adjacent the
soft tissue, the first clamp including a first surface and a convex
tissue engaging surface opposite the first surface, inserting a
fastener through a throughhole in the first clamp, through the soft
tissue and into the tibia such that the soft tissue is compressed
between the tissue engaging surface and the tibia; positioning the
soft tissue between a first part and a mating second part of a
second attachment device such that the soft tissue is compressed
between the first part and the second part, the first part
comprising a porous metallic material and the second part
comprising a porous metallic material, and securing the second
attachment device in a tunnel of the femur.
19. The method of claim 18 wherein: the soft tissue is a ligament
replacement.
20. The method of claim 18 wherein: the first part comprises a
first channel, the second part comprises a second channel, and the
soft tissue is compressed between an inner surface of the first
channel of the first part and an inner surface of the second
channel of the second part.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. patent
application Ser. No. 12/612,205, filed Nov. 4, 2009, which claims
priority based on U.S. Provisional Application No. 61/111,051 filed
Nov. 4, 2008.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] Not Applicable.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The invention relates to methods and devices for the
attachment of a tendon or ligament structure to bone and/or a
prosthetic implant (such as a joint replacement device). In
particular, the methods and devices use a clamping strategy
employing soft tissue healing to a porous metal clamp.
[0005] 2. Description of the Related Art
[0006] Surgical techniques in which a tendon is fixed directly to
bone have been successful in achieving a strong tendon-bone
attachment in selected circumstances. However, when tendon is
directly fixed to metallic implants, weak fixation and mechanical
failure under physiologic loading have been observed.
[0007] It has been shown that porous tantalum can function as a
soft-tissue attachment and repair biomaterial. In "Direct Tendon
Attachment and Healing to Porous Tantalum: An Experimental Animal
Study", The Journal Of Bone And Joint Surgery, 2007; 89:1000-9, an
animal model was used to demonstrate the potential utility of
porous metals to achieve healing of tendon directly to a porous
metallic device. Example ligament attachment devices can also be
found in U.S. Pat. No. 7,208,222 and U.S. Patent Application
Publication No. 2007/0162022.
[0008] Still, there exists a need for improved methods and devices
for the attachment of a tendon or ligament structure to bone or a
prosthetic implant.
SUMMARY OF THE INVENTION
[0009] The present invention addresses the foregoing needs by
providing porous metal (such as tantalum or titanium) devices to
attach (via screw or screws) soft tissue (tendons or ligaments) to
bone or to prosthetic implants. Porous metal allows the ingrowth of
soft tissue. The attachment devices of the invention can allow
varying degrees of soft tissue compression due to the difference in
curvature of (i) a first convex clamp and (ii) a second concave
clamp, or a concave depression in bone or an implant. Compression
of a tendon or ligament between a concave porous ingrowth surface
on one side, and a convex surface of smaller radius of curvature on
the other allows for varying degrees of compression. In other
words, the gap between the concave porous ingrowth surface on one
side and the convex surface on the other side gets bigger near the
outer edge of the clamp or depression and is smallest
centrally.
[0010] Because tendons and ligaments are of different thicknesses
and have different requirements for clamping tension, having
varying degrees of compression in the invention increases the
likelihood that at some point along the curvature of the clamp(s),
the level of compression would be optimal for ingrowth of soft
tissue and implant success rates would increase. Also, compression
across the soft tissue-clamp interface at varying degrees negates
needing to find perfect tension. As a result, soft tissue ingrowth
into metal is achieved because compression is just right.
Furthermore, the soft tissue is flat in the center of the
clamp.
[0011] In one aspect, the invention provides a device for attaching
soft tissue to a bone or a prosthetic implant. The device includes
a clamp and a fastener. The clamp comprises a porous metallic
material, and the clamp includes a first surface, a convex tissue
engaging surface opposite the first surface, and a throughhole
extending from the first surface to the convex tissue engaging
surface. The fastener is dimensioned for placement in the
throughhole, and the fastener is dimensioned to engage the first
surface, the soft tissue and the bone or the prosthetic implant
such that the soft tissue is compressed between the tissue engaging
surface and the bone or the prosthetic implant.
[0012] In one form, the convex tissue engaging surface of the clamp
has a first curvature, the bone or the prosthetic implant includes
a depression of a second curvature, and the first curvature is
greater than the second curvature. The convex tissue engaging
surface of the clamp can be dome shaped. A grommet can be arranged
in the throughhole. The convex tissue engaging surface of the clamp
can include a raised section around the throughhole. The clamp can
include a second throughhole for receiving a second fastener.
Various shapes are suitable for the clamp. For example, the clamp
can include a periphery having a shape selected from circular,
rectangular, elliptical and oval.
[0013] The device can include a second clamp comprising a porous
metallic material. The second clamp can include a first part and a
mating second part wherein the soft tissue is compressed between
the first part and the second part. In one form, the first part
comprises a first channel, the second part comprises a second
channel, and the soft tissue is compressed between an inner surface
of the first channel of the first part and an inner surface of the
second channel of the second part. The first part and the second
part can form a frustoconical shape when mated together.
[0014] In another aspect, the invention provides a device for
attaching soft tissue to a bone or a prosthetic implant. The device
includes a first clamp, a second clamp, and a fastener. The first
clamp comprises a porous metallic material. The first clamp
includes a first surface, a convex tissue engaging surface opposite
the first surface, and a throughhole extending from the first
surface to the convex tissue engaging surface of the first clamp.
The convex tissue engaging surface of the first clamp can be dome
shaped. The second clamp comprises a porous metallic material. The
second clamp includes a first surface, a concave tissue engaging
surface opposite the first surface, and a throughhole extending
from the first surface to the concave tissue engaging surface of
the second clamp. The fastener is dimensioned for placement in the
throughhole of the first clamp and the throughhole of the second
clamp. The fastener is dimensioned to engage the first surface of
the first clamp, the soft tissue and the bone or the prosthetic
implant such that the soft tissue is compressed between the convex
tissue engaging surface of the first clamp and the concave tissue
engaging surface of the second clamp.
[0015] In one form, the convex tissue engaging surface of the first
clamp has a first curvature, the concave tissue engaging surface of
the second clamp has a second curvature, and the first curvature is
greater than the second curvature. The first clamp can include a
periphery having a shape selected from circular, rectangular,
elliptical and oval, and the second clamp can include a periphery
having a shape selected from circular, rectangular, elliptical and
oval. In one use of the device, a depression is formed in a bone,
and the second clamp is received in the depression of the bone. The
porous metallic material of the first clamp can be tantalum, and
the porous metallic material of the second clamp can be
tantalum.
[0016] In yet another aspect, the invention provides a method for
attaching soft tissue to a bone. The method uses a clamp comprising
a porous metallic material wherein the clamp includes a first
surface, a convex tissue engaging surface opposite the first
surface, and a throughhole extending from the first surface to the
convex tissue engaging surface. The soft tissue is placed adjacent
the bone, and the clamp is placed adjacent the soft tissue opposite
the bone. A fastener is inserted through the throughhole, through
the soft tissue and into the bone such that the soft tissue is
compressed between the tissue engaging surface and the bone. The
convex tissue engaging surface of the clamp can have a first
curvature, and the method can further comprise forming a depression
of a second curvature in the bone, wherein the first curvature of
the convex tissue engaging surface of the clamp is greater than the
second curvature of the depression. The soft tissue is placed in
the depression such that the soft tissue is compressed between the
convex tissue engaging surface and the bone.
[0017] In still another aspect, the invention provides a method for
attaching soft tissue to a prosthetic implant. The method uses a
clamp comprising a porous metallic material. The clamp includes a
first surface, a convex tissue engaging surface opposite the first
surface, and a throughhole extending from the first surface to the
convex tissue engaging surface. The soft tissue is placed adjacent
the prosthetic implant, and the clamp is placed adjacent the soft
tissue opposite the implant. A fastener is inserted through the
throughhole, through the soft tissue and into the prosthetic
implant such that the soft tissue is compressed between the tissue
engaging surface and the prosthetic implant. The convex tissue
engaging surface of the clamp can have a first curvature, and the
prosthetic implant can further comprise a depression of a second
curvature in the prosthetic implant, wherein the first curvature of
the convex tissue engaging surface of the clamp is greater than the
second curvature of the depression. The soft tissue is placed in
the depression such that the soft tissue is compressed between the
convex tissue engaging surface and the prosthetic implant.
[0018] In yet another aspect, the invention provides a method for
attaching soft tissue to a bone. The method uses a first clamp
comprising a porous metallic material and a second clamp comprising
a porous metallic material. The first clamp includes a first
surface, a convex tissue engaging surface opposite the first
surface, and a throughhole extending from the first surface to the
convex tissue engaging surface. The second clamp includes a first
surface, a concave tissue engaging surface opposite the first
surface, and a throughhole extending from the first surface to the
concave tissue engaging surface. The second clamp is placed
adjacent the bone, and the soft tissue is placed adjacent the
second clamp opposite the bone. The first clamp is placed adjacent
the soft tissue opposite the second clamp, and a fastener is
inserted through the throughhole of the first clamp, through the
soft tissue, through the throughhole of the second clamp and into
the bone such that the soft tissue is compressed between the convex
tissue engaging surface of the first clamp and the concave tissue
engaging surface of the second clamp. The convex tissue engaging
surface of the first clamp can have a first curvature, and the
concave tissue engaging surface of the second clamp can have a
second curvature, wherein the first curvature is greater than the
second curvature.
[0019] It is therefore an advantage of the invention to provide
improved methods and devices for the attachment of a tendon or
ligament structure to bone or to a prosthetic implant.
[0020] These and other features, aspects, and advantages of the
present invention will become better understood upon consideration
of the following detailed description, drawings, and appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a perspective view of a human knee having a
ligament attached to the femur and the tibia using an attachment
device according to the invention.
[0022] FIG. 2 is a detailed cross-sectional view of the attachment
device according to the invention taken along line 2-2 of FIG.
1.
[0023] FIG. 3 is a lateral view taken along line 3-3 of FIG. 2.
[0024] FIG. 4 is a lateral view similar to FIG. 3 showing another
version of an attachment device according to the invention.
[0025] FIG. 5 is a lateral view similar to FIG. 3 showing yet
another version of an attachment device according to the
invention.
[0026] FIG. 6 a detailed cross-sectional view similar to FIG. 2
showing still another version of an attachment device according to
the invention.
[0027] FIG. 7 is a perspective view of a human knee having a
ligament attached to the femur and the tibia using yet another
version of an attachment device according to the invention.
[0028] FIG. 8 is a perspective view showing an attachment device of
FIG. 7.
[0029] FIG. 9 is a side view of a prior art femoral prosthesis.
[0030] FIG. 10 is a side view, partially in cross-section, of a
femoral prosthesis including still another attachment device
according to the invention.
[0031] FIG. 11 is a lateral view taken along line 11-11 of FIG.
10.
[0032] FIG. 12 is a detailed cross-sectional view similar to FIG. 2
showing still another version of an attachment device according to
the invention.
[0033] Like reference numerals will be used to refer to like parts
from Figure to Figure in the following description of the
drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0034] Looking first at FIG. 1, there is shown an example
application of an attachment device 10 according to the invention
in a human knee. This is shown for illustrative purposes, and the
attachment device is not limited to knee surgery. The attachment
device 10 can be used to attach any soft tissue (such as tendons
and ligaments) to any bone. In FIG. 1, the knee joint 12 is shown
with femur 14, tibia 16, tibial tunnel 18 and femoral tunnel 20.
The tibial tunnel 18 and the femoral tunnel 20 can be prepared
using standard techniques. A ligament replacement 22 is arranged in
the tibial tunnel 18 and the femoral tunnel 20. A top end 24 of the
ligament replacement 22 is attached to the femur 14 using the
attachment device 10 and a bottom end 26 of the ligament
replacement 22 is attached to the tibia 16 using the attachment
device 10.
[0035] Turning to FIGS. 2 and 3, the attachment device 10 is shown
in greater detail. The attachment device 10 includes a clamp 30
having a domed (convex) tissue engaging surface 32, a circular
periphery 34, a bottom surface 36, and a central throughhole 38. A
tubular grommet 40 is arranged in the throughhole 38. The side wall
42 of the grommet 40 can engage the inner surface of the
throughhole 38. and a flange 44 extends outwardly from an end of
the side wall 42. The grommet 40 is optional, but can be
advantageous as the grommet 40 can prevent the ligament replacement
22 at the apex of the clamp 30 from being totally flattened. The
attachment device 10 also includes a fastener such as screw 46 that
is inserted through the grommet 40, through the ligament
replacement 22, and into the tibia 16. The screw 46 compresses the
ligament replacement 22 between the clamp 30 and the tibia 16. Note
in FIG. 2 how the gap between the convex porous ingrowth surface 32
on one side and the concave surface of the depression 48 on the
other side gets bigger near the periphery 34 of the clamp 30 and is
smallest centrally near screw 46.
[0036] In an alternative embodiment, the grommet 40 is omitted and
the convex tissue engaging surface 32 includes a raised section
around the throughhole 38. This raised section can have an annular
shape equivalent to the flange 44 of the grommet 40. This raised
section can prevent the ligament replacement 22 at the apex of the
clamp 30 from being totally flattened.
[0037] The tissue engaging surface 32 of the clamp 30 has a first
curvature which can be calculated as the inverse of the radius from
a point P (which is on the central axis of the throughhole 38 and
which is in the plane of the bottom surface 36) to various points
on the tissue engaging surface 32. The ligament replacement 22 is
secured between the tissue engaging surface 32 and a depression 48
that can be formed in the tibia 16. The depression 48 has a second
curvature which can be calculated as the inverse of the radius from
point P (which is on the central axis of the throughhole 38a and
which is in the plane of the bottom surface 36) to various points
on the inner surface of the depression 48. Also, the depression 48
can be prepared with a depth such that the flat bottom surface 36
of the clamp 30 can be counter-sunk into the tibia 16 if
desired.
[0038] The clamp 30 and the grommet 40 may comprise a material that
promotes soft tissue ingrowth from the ligament replacement 22 into
the clamp 30 and the grommet 40. One non-limiting example material
is a porous metallic material, also known as metal foam, which can
be produced with interconnective porosity coupled with a regular
pore shape and size. One such material that is currently
commercially available for a variety of orthopedic implants
involves the elemental metal tantalum fabricated with >80%
interconnective porosity with use of a metal vapor deposition
technique (Trabecular Metal from Zimmer, Warsaw, Ind., USA). This
material is also described in U.S. Pat. No. 5,282,861 which is
incorporated herein by reference. While tantalum is one example
porous metallic material, other non-limiting example porous
metallic materials include titanium alloys, cobalt-chromium alloys,
stainless steel alloys, tantalum alloys, and niobium alloys. The
screw 46 is preferably formed from a non-porous metallic material
such as a titanium alloy or a stainless steel alloy.
[0039] Still referring to FIGS. 2 and 3, it can be seen that the
first curvature of the convex tissue engaging surface 32 of the
clamp 30 is greater than the second curvature of the depression 48
in the tibia 16. Stated in another way, the radius curvature of the
convex tissue engaging surface 32 of the clamp 30 is smaller than
the radius of curvature of the depression 48 in the tibia 16. This
allows for varying degrees of ligament replacement 22 compression
due to the difference in curvature of the first curvature of the
convex tissue engaging surface 32 of the clamp 30 and the second
curvature of the depression 48 in the tibia 16. As tendons and
ligaments are of different thicknesses and have different
requirements for tension between the clamp 30 and the tibia 16,
having varying degrees of compression between the clamp 30 and the
tibia 16 increases the likelihood that at some point along the
convex tissue engaging surface 32 of the clamp 30, the level of
compression would be optimal for ingrowth of soft tissue and
therefore implant success rates increase.
[0040] Turning to FIG. 4, an alternative embodiment of the clamp of
the attachment device is shown. The clamp 30a has a generally
rectangular periphery 34a, and two throughholes 38a and 39a, which
allow for the use of two screws and optionally two grommets. The
use of two screws for compressing the ligament replacement 22
between the clamp 30a and the tibia 16 can increase compression
force on the ligament replacement 22. The rectangular periphery 34a
of the clamp 30a can provide for increased surface area for soft
tissue ingrowth. The clamp 30a can comprise the porous metallic
materials mentioned above. The convex tissue engaging surface of
the clamp 30a can have a radius curvature similar to the radius of
curvature of the convex tissue engaging surface 32 of the clamp 30
shown in FIG. 2.
[0041] Turning to FIG. 5, another alternative embodiment of the
clamp of the attachment device is shown. The clamp 30b has a
generally oval periphery 34b, and two throughholes 38b and 39b,
which allow for the use of two screws and optionally two grommets.
The use of two screws for compressing the ligament replacement 22
between the clamp 30b and the tibia 16 can increase compression
force on the ligament replacement 22. The oval periphery 34b of the
clamp 30b can provide for increased surface area for soft tissue
ingrowth. The clamp 30b can comprise the porous metallic materials
mentioned above. The convex tissue engaging surface of the clamp
30b can have a radius curvature similar to the radius of curvature
of the convex tissue engaging surface 32 of the clamp 30 shown in
FIG. 2.
[0042] Looking now at FIG. 6, there is shown another embodiment of
an attachment device 110 according to the invention. The attachment
device 110 includes a first clamp 130 having a domed (convex)
tissue engaging surface 132, a circular periphery 134, a bottom
surface 136, and a central throughhole 138. The attachment device
110 also includes a second clamp 141 having a concave tissue
engaging surface 142 in a well, a circular periphery 143, a bottom
surface 144, and a central throughhole 145. The attachment device
110 also includes a fastener such as screw 146 that is inserted
through the throughhole 138, through the ligament replacement 22,
through the throughhole 145, and into the tibia 16. The screw 146
compresses the ligament replacement 22 between the first clamp 130
and the second clamp 141, which can be inserted in a circular
depression 148 formed in the tibia 16. While the first clamp 130
shown has a circular periphery 134 and the second clamp 141 shown
has a circular periphery 143, the periphery of each of the first
clamp 130 and the second clamp 141 can have different shapes such
as shown in FIGS. 4 and 5.
[0043] The tissue engaging surface 132 of the first clamp 130 has a
first curvature which can be calculated as the inverse of the
radius from a point (which is on the central axis of the
throughhole 138 and which is in the plane of the bottom surface
136) to various points on the tissue engaging surface 132. The
concave tissue engaging surface 142 of the second clamp 141 has a
second curvature which can be calculated as the inverse of the
radius from a point (which is on the central axis of the
throughhole 138 and which is in the plane of the bottom surface
136) to various points on the concave tissue engaging surface 142
of the second clamp 141.
[0044] The first curvature of the convex tissue engaging surface
132 of the clamp 130 is greater than the second curvature of the
concave tissue engaging surface 142 of the second clamp 141. Stated
in another way, the radius curvature of the convex tissue engaging
surface 132 of the clamp 130 is smaller than the radius of
curvature of the concave tissue engaging surface 142 of the second
clamp 141. This allows for varying degrees of ligament replacement
22 compression due to the difference in curvature of the first
curvature of the convex tissue engaging surface 132 of the clamp
130 and the second curvature of the concave tissue engaging surface
142 of the second clamp 141. Note in FIG. 6 how the gap between the
convex porous ingrowth surface 132 on one side and the concave
tissue engaging surface 142 of the second clamp 141 on the other
side gets bigger near the periphery 134 of the clamp 130 and is
smallest centrally near screw 146. As tendons and ligaments are of
different thicknesses and have different requirements for tension
between the first clamp 130 and the second clamp 141, having
varying degrees of compression between the first clamp 130 and the
second clamp 141 increases the likelihood that at some point along
the convex tissue engaging surface 132 of the first clamp 130 and
the concave tissue engaging surface 142 of the second clamp 141,
the level of compression would be optimal for ingrowth of soft
tissue and therefore implant success rates increase.
[0045] The first clamp 130 and the second clamp 141 may comprise a
material that promotes soft tissue ingrowth from the ligament
replacement 22 into first clamp 130 and the second clamp 141 The
first clamp 130 and the second clamp 141 can comprise the porous
metallic materials mentioned above for clamp 30.
[0046] Turning now to FIGS. 7 and 8, the knee joint 12 is shown
with femur 14, tibia 16, tibial tunnel 18 and femoral tunnel 20.
The tibial tunnel 18 and the femoral tunnel 20 can be prepared
using standard techniques. A ligament replacement 22 is arranged in
the tibial tunnel 18 and the femoral tunnel 20. A top end of the
ligament replacement 22 is attached to the femur 14 in the femoral
tunnel 20 using the another attachment device 210 according to the
invention. The bottom end 26 of the ligament replacement 22 is
attached to the tibia 16 using the attachment device 10 as
described above. The attachment device 210 as shown in FIG. 8 forms
a two-part frustoconical clamp 230. The clamp 230 includes a first
curved channel 232 having a wall 233 that terminates in a first
longitudinal edge 234 and a second longitudinal edge 236. The wall
233 has a first semicircular end 237 and a second semicircular end
238 of greater radius than the first semicircular end 237. The
clamp 230 also includes a second curved channel 242 having a wall
243 that terminates in a first longitudinal edge 244 and a second
longitudinal edge 246. The wall 243 has a first semicircular end
247 and a second semicircular end 248 of greater radius than the
first semicircular end 247. When the first edge 234 and the second
edge 236 of the first channel 232 are brought into mating contact
with the first edge 244 and the second edge 246 of the second
channel 242 respectively, the clamp 230 has a hollow frustoconical
shape. The first channel 232 and the second channel 242 can
comprise the porous metallic materials mentioned above for clamp
30.
[0047] To use the attachment device 210, the ligament replacement
22 is positioned between the first channel 232 and the second
channel 242, and the first edge 234 and the second edge 236 of the
first channel 232 are brought near the first edge 244 and the
second edge 246 of the second channel 242 respectively. The clamp
230 is then inserted into the femoral tunnel 20 with the first
semicircular end 237 and the first semicircular end 247 going in
first. The first channel 232 and the second channel 242 clamp the
ligament replacement 22, and are wedged against the inner surface
19 of the femoral tunnel 20. The compression of the ligament
replacement 22 allows for ingrowth of soft tissue into the first
channel 232 and the second channel 242 and therefore the implant
success rate increases.
[0048] Referring now to FIG. 9, there is shown a prior art femoral
prosthesis 310 that may be implanted in a resected femur as part of
a hip replacement procedure. The prosthesis 310 includes a body 312
having a neck portion 313, a femoral head 314 and a collar 315. The
femoral head 314 is received in an acetabular component (not shown)
that is mounted in a patient's pelvis as is well known in the art.
Extending away from the body 312 of the prosthesis 310 is a
generally cylindrical or tubular stem 316 that is inserted within
the intramedullary canal of the femur 14. The stem 316 has an upper
lateral corner 317. The femoral prosthesis 310 may be formed from a
metal alloy such as titanium alloys (e.g.,
titanium-6-aluminum-4-vanadium), cobalt-chromium alloys, stainless
steel alloys and tantalum alloys; nonresorbable ceramics such as
aluminum oxide and zirconia; nonresorbable polymeric materials such
as polyethylene; or composite materials such as carbon
fiber-reinforced polymers (e.g., polysulfone).
[0049] Turning to FIGS. 10 and 11, another attachment device 410
according to the invention is shown. The prosthesis 310a is similar
to the prosthesis 310 of FIG. 9. The prosthesis 310a includes a
body 312a having a neck portion 313a, a femoral head 314a and a
collar 315a. However, an indented section 420 of the upper lateral
corner 417 of the prosthesis 310a has been removed. The attachment
device 410 includes a clamp 430 having a convex tissue engaging
surface 432, a generally rectangular periphery 434, a bottom
surface 436, and throughholes 438 and 439. In the cross-section
shown in FIG. 10, the clamp 430 has a general shape of a quadrant
of an oval. The clamp 430 may comprise a material that promotes
soft tissue ingrowth from the ligament replacement 22 into clamp
430. The clamp 430 can comprise the porous metallic materials
mentioned above for clamp 30.
[0050] The attachment device 410 also includes fasteners such as
screws 446, 447 that are inserted through the throughholes 438,
439, respectively, through the ligament replacement 22, and into
the stem 316a of the prosthesis 310a. The screws 446, 447 compress
the ligament replacement 22 between the convex tissue engaging
surface 432 of the clamp 430 and the concave tissue engaging
surface 442 of the indented section 420 of the stem 316a of the
prosthesis 310a. The convex tissue engaging surface 432 of the
clamp 430 has a first curvature is greater than the second
curvature of the concave tissue engaging surface 442. This allows
for varying degrees of ligament replacement 22 compression due to
the difference in curvature of the first curvature of the convex
tissue engaging surface 432 of the clamp 430 and the second
curvature of the concave tissue engaging surface 442. Either end of
the ligament replacement 22 can be attached to another bone or
implant.
[0051] Looking now at FIG. 12, there is shown another embodiment of
an attachment device 510 according to the invention. The attachment
device 510 includes a first clamp 530 having a domed (convex)
tissue engaging surface 532, a circular periphery 534, a bottom
surface 536, and a central throughhole 538. The attachment device
510 also includes a second clamp 541 having a concave tissue
engaging surface 542 in a well, a circular periphery 543, a bottom
surface 544, and a central throughhole 545. The attachment device
510 also includes a fastener such as screw 546 that is inserted
through the throughhole 538, through the ligament replacement 22,
through the throughhole 545, and into the tibia 16. The screw 546
compresses the ligament replacement 22 between the first clamp 530
and the second clamp 541, which can be inserted in a recess 548
formed in the tibia 16.
[0052] The tissue engaging surface 532 of the first clamp 530 has a
first curvature which can be calculated as the inverse of the
radius from a point (which is on the central axis of the
throughhole 538 and which is in the plane of the bottom surface
536) to various points on the tissue engaging surface 532. The
concave tissue engaging surface 542 of the second clamp 541 has a
second curvature which can be calculated as the inverse of the
radius from a point (which is on the central axis of the
throughhole 538 and which is in the plane of the bottom surface
536) to various points on the concave tissue engaging surface 542
of the second clamp 541.
[0053] The first curvature of the convex tissue engaging surface
532 of the clamp 530 is greater than the second curvature of the
concave tissue engaging surface 542 of the second clamp 541. This
allows for varying degrees of ligament replacement 22 compression
due to the difference in curvature of the first curvature of the
convex tissue engaging surface 532 of the clamp 530 and the second
curvature of the concave tissue engaging surface 542 of the second
clamp 541. Note in FIG. 12 how the gap between the convex porous
ingrowth surface 532 on one side and the concave tissue engaging
surface 542 of the second clamp 542 on the other side gets bigger
near the periphery 534 of the clamp 530 and is smallest centrally
near screw 546. As tendons and ligaments are of different
thicknesses and have different requirements for tension between the
first clamp 530 and the second clamp 541, having varying degrees of
compression between the first clamp 530 and the second clamp 541
increases the likelihood that at some point along the convex tissue
engaging surface 532 of the first clamp 530 and the concave tissue
engaging surface 542 of the second clamp 541, the level of
compression would be optimal for ingrowth of soft tissue and
therefore implant success rates increase.
[0054] The first clamp 530 and the second clamp 541 may comprise a
material that promotes soft tissue ingrowth from the ligament
replacement 22 into first clamp 530 and the second clamp 541 The
first clamp 530 and the second clamp 541 can comprise the porous
metallic materials mentioned above for clamp 30.
[0055] Thus, the invention provides methods and devices for the
attachment of a tendon or ligament structure to bone and/or a
prosthetic implant (such as a joint replacement device). In
particular, the methods and devices use a clamping strategy
employing soft tissue healing to a porous metal clamp.
[0056] Although the present invention has been described in detail
with reference to certain embodiments, one skilled in the art will
appreciate that the present invention can be practiced by other
than the described embodiments, which have been presented for
purposes of illustration and not of limitation. Therefore, the
scope of the appended claims should not be limited to the
description of the embodiments contained herein.
* * * * *