U.S. patent application number 10/624675 was filed with the patent office on 2004-05-06 for tissue fastener.
Invention is credited to Berube, Rod, Ek, Steve, Lipchitz, John, Torrie, Paul A..
Application Number | 20040087981 10/624675 |
Document ID | / |
Family ID | 23948429 |
Filed Date | 2004-05-06 |
United States Patent
Application |
20040087981 |
Kind Code |
A1 |
Berube, Rod ; et
al. |
May 6, 2004 |
Tissue fastener
Abstract
A tissue fastener comprises a shaft having a member disposed
thereon for lodging the shaft within the tissue, the shaft having a
region that is relatively flexible to render a tissue engaging head
disposed at a proximal end of the shaft movable with respect to the
shaft. In one embodiment, the region comprises substantially an
entire length of the shaft and is made from flexible material, such
as a mesh, onto which the member and the head are molded. In
another embodiment, the shaft comprises generally rigid material,
and the region comprises a flexible joint between the shaft and the
head. The flexible joint comprises a breakable (e.g., frangible)
section of the shaft, and a flexible member (e.g., a plurality of
filaments or a flexible tube) extends between the shaft and the
head past the breakable section.
Inventors: |
Berube, Rod; (North
Attleboro, MA) ; Torrie, Paul A.; (Marblehead,
MA) ; Ek, Steve; (Bolton, MA) ; Lipchitz,
John; (Tewksbury, MA) |
Correspondence
Address: |
FISH & RICHARDSON P.C.
1425 K STREET, N.W.
11TH FLOOR
WASHINGTON
DC
20005-3500
US
|
Family ID: |
23948429 |
Appl. No.: |
10/624675 |
Filed: |
July 23, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10624675 |
Jul 23, 2003 |
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09490525 |
Jan 25, 2000 |
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6623492 |
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Current U.S.
Class: |
606/151 |
Current CPC
Class: |
A61F 2002/0841 20130101;
Y10S 606/91 20130101; A61B 2017/00004 20130101; A61B 17/0642
20130101; A61F 2/0811 20130101; A61F 2002/0858 20130101; A61F
2002/0888 20130101; A61B 17/068 20130101; A61B 2017/0646 20130101;
Y10S 606/908 20130101; A61B 2017/0647 20130101 |
Class at
Publication: |
606/151 |
International
Class: |
A61B 017/08 |
Claims
What is claimed is:
1. A tissue fastener comprising a shaft having a member disposed
thereon for lodging the shaft within the tissue, and a tissue
engaging head disposed at a proximal end of the shaft, a region of
the shaft being relatively flexible to render the head movable with
respect to the shaft.
2. The tissue fastener of claim 1 wherein the region comprises
substantially an entire length of the shaft.
3. The tissue fastener of claim 2 wherein the region comprises
flexible material.
4. The tissue fastener of claim 3 wherein the flexible material
comprises a mesh.
5. The tissue fastener of claim 1 wherein the shaft comprises a
mesh material, the member and the head being molded onto the
mesh.
6. The tissue fastener of claim 1 wherein the member comprises at
least one barb.
7. The tissue fastener of claim 1 wherein the shaft comprises
generally rigid material and the region comprises a flexible joint
between the shaft and the head.
8. The tissue fastener of claim 7 wherein the flexible joint
comprises a frangible section of the shaft, and further comprising
a flexible member extending between the shaft and the head past the
frangible section.
9. The tissue fastener of claim 8 wherein the breakable section is
defined by at least one opening disposed through a wall of the
shaft.
10. The tissue fastener of claim 8 wherein the flexible member
comprises a plurality of filaments.
11. The tissue fastener of claim 8 wherein the flexible member
comprises a flexible tube.
12. The tissue fastener of claim 8 wherein the flexible member
extends along substantially an entire length of the shaft.
13. The tissue fastener of claim 8 wherein the shaft and the head
comprise an integral molded unit, the flexible member being molded
therewithin.
14. The tissue fastener of claim 1 made from polymeric
material.
15. The tissue fastener of claim 1 made from bioabsorbable
material.
16. The tissue fastener of claim 1 wherein the shaft is hollow and
defines an interior passage, the head including an opening in
communication with the passage.
17. The tissue fastener of claim 16 wherein the passage is open at
a distal end of the shaft.
18. The tissue fastener of claim 16 wherein the passage is closed
at a distal end of the shaft.
19. The tissue fastener of claim 1 wherein the head has a flat
distal surface.
20. The tissue fastener of claim 1 wherein the head has a toothed
distal surface.
21. A tissue fastener comprising a shaft, a member disposed at a
distal region of the shaft for lodging the shaft within the tissue,
and a tissue engaging head disposed at a proximal end of the shaft,
the shaft being relatively flexible between the member and the head
to render the head movable with respect to the shaft.
22. The tissue fastener of claim 21 wherein the shaft comprises a
mesh extending between the member and the head.
23. A tissue fastener comprising a generally rigid shaft having a
member disposed thereon for lodging the shaft within the tissue, a
tissue engaging head disposed at a proximal end of the shaft, and a
flexible joint between the shaft and the head to render the head
movable with respect to the shaft.
24. The tissue fastener of claim 23 wherein the flexible joint
comprises a breakable section of the shaft, and further comprising
a flexible member extending between the shaft and the head past the
breakable section.
25. The tissue fastener of claim 24 wherein the breakable section
is frangible.
26. The tissue fastener of claim 23 wherein the flexible member
comprises a plurality of filaments.
27. The tissue fastener of claim 23 wherein the flexible member
comprises a flexible tube.
28. Apparatus comprising a tissue fastener comprising a shaft
having a member disposed thereon for lodging the shaft within the
tissue, and a tissue engaging head disposed at a proximal end of
the shaft, a region of the shaft being relatively flexible to
render the head movable with respect to the shaft, and an insertion
tool engageable with the tissue fastener for inserting the tissue
fastener into tissue.
29. The apparatus of claim 28 wherein the member is disposed at a
distal region of the shaft for lodging the shaft within the tissue,
the tissue engaging head is disposed at a proximal end of the
shaft, and the shaft is relatively flexible between the member and
the head, the insertion tool comprising an engagement portion for
engaging the member.
30. The apparatus of claim 29 wherein the head includes an
aperture, the engagement portion of the tool being configured to
extend through the aperture when engaged with the member.
31. A method for tissue attachment comprising providing a tissue
fastener comprising a shaft having a member disposed thereon for
lodging the shaft within the tissue, and a tissue engaging head
disposed at a proximal end of the shaft, a region of the shaft
being relatively flexible to render the head movable with respect
to the shaft, and inserting the tissue fastener through a first
tissue and into a second tissue so that the member lodges within
the second tissue and the head urges the first tissue against the
second tissue.
32. The method of claim 31 wherein the first tissue and the second
tissue are regions of a common tissue structure.
33. The method of claim 32 wherein the tissue structure is
cartilage and, prior to the inserting, the first region is
separated from the second region by a tear in the cartilage.
34. The method of claim 31 wherein the first tissue is soft tissue
and the second tissue is bone.
35. A method for making a tissue fastener comprising providing a
shaft having a member disposed thereon for lodging the shaft within
the tissue, and a tissue engaging head disposed at a proximal end
of the shaft, and making a region of the shaft relatively flexible
to render the head movable with respect to the shaft.
36. The method of claim 35 further comprising making the region
comprise substantially an entire length of the shaft.
37. The method of claim 36 further comprising making the region
from flexible material.
38. The method of claim 37 wherein the flexible material comprises
a mesh.
39. The method of claim 35 wherein the shaft comprises a mesh
material, and further comprising molding the member and the head
onto the mesh.
40. The method of claim 35 wherein the shaft comprises generally
rigid material, the making comprising forming a flexible joint
between the shaft and the head in the region.
41. The method of claim 40 wherein the forming comprises providing
a breakable section of the shaft, and further comprising extending
a flexible member between the shaft and the head past the breakable
section.
42. The method of claim 41 further comprising forming the breakable
section to be frangible.
43. The method of claim 42 further comprising defining the
breakable section by at least one opening disposed through a wall
of the shaft.
44. The method of claim 41 wherein the flexible member comprises a
plurality of filaments.
45. The method of claim 41 wherein the flexible member comprises a
flexible tube.
46. The method of claim 41 further comprising extending the
flexible member along substantially an entire length of the
shaft.
47. The method of claim 41 further comprising molding the shaft
and-the head as an integral unit, and molding the flexible member
therewithin.
48. The method of claim 35 further comprising making the tissue
fastener from polymeric material.
49. The method of claim 35 further comprising making the tissue
fastener from bioabsorbable material.
50. The method of claim 35 further comprising providing the shaft
with an interior passage, and forming an opening in the head in
communication with the passage.
51. The method of claim 50 further comprising opening the passage
at a distal end of the shaft.
52. The method of claim 50 further comprising closing the passage
at a distal end of the shaft.
53. The method of claim 35 further comprising providing the head
with a flat distal surface.
54. The method of claim 35 further comprising providing the head
with a toothed distal surface.
Description
BACKGROUND
[0001] This invention relates to tissue fasteners, in particular to
devices for attaching soft tissue (e.g., tendons, ligaments, or
cartilage) to bone or to other soft tissue.
[0002] One conventional tissue fastener used to re-attach cartilage
to bone comprises an elongated shaft with a series of barbs that
enable the shaft to be inserted through tissue but resist
withdrawal thereafter. The distal tip of the shaft is sharp, and
the proximal end of the shaft terminates at an enlarged head. To
re-attach soft tissue to bone, the fastener is pushed through the
soft tissue into a pre-formed hole in the bone until the soft
tissue is secured between the head and the bone surface. The barbs
resist withdrawal from the hole, thereby holding the fastener (and
thus the soft tissue) in place.
SUMMARY
[0003] One aspect of the invention features a tissue fastener
comprising a shaft having a member disposed thereon for lodging the
shaft within the tissue, the shaft having a region that is
relatively flexible to render a tissue engaging head disposed at a
proximal end of the shaft movable with respect to the shaft.
[0004] Preferred embodiments may include one or more of the
following features.
[0005] In one embodiment, the region comprises substantially an
entire length of the shaft. The region comprises flexible material,
such as a mesh. The member and the head are molded onto the mesh.
The member comprises at least one barb.
[0006] In another embodiment, the shaft comprises generally rigid
material, and the region comprises a flexible joint between the
shaft and the head. The flexible joint comprises a breakable
section of the shaft. For example, the section is constructed to be
frangible (i.e., readily broken). A flexible member extends between
the shaft and the head past the breakable section. The flexible
member comprises, e.g., a plurality of filaments or a flexible
tube. The flexible member extends along substantially an entire
length of the shaft. The breakable section is defined by at least
one opening disposed through a wall of the shaft. The shaft and the
head comprise an integral molded unit, and the flexible member is
molded therewithin.
[0007] The tissue fastener is made from polymeric material, such as
a bioabsorbable material. The shaft is hollow and defines an
interior passage. The head includes an opening in communication
with the passage. The passage may be open or closed at a distal end
of the shaft.
[0008] In one embodiment, the head has a flat distal surface. In
another approach, the head has a toothed distal surface.
[0009] Another aspect of the invention features the tissue fastener
and an insertion tool engageable with the tissue fastener for
inserting the tissue fastener into tissue.
[0010] Preferred embodiments may include one or more of the
following features. The tissue fastener member is disposed at a
distal region of the shaft for lodging the shaft within the tissue,
and the tissue engaging head is disposed at a proximal end of the
shaft, and the shaft is relatively flexible between the member and
the head. The insertion tool has an engagement portion for engaging
the member. The head includes an aperture, and the engagement
portion of the tool is configured to extend through the aperture
when engaged with the member.
[0011] Other aspects of the invention feature methods for tissue
attachment using the tissue fastener. One such method comprises
inserting the tissue fastener through a first tissue and into a
second tissue so that the member lodges within the second tissue
and the head urges the first tissue against the second tissue.
[0012] Preferred embodiments may include one or more of the
following features.
[0013] The first tissue and the second tissue are regions of a
common tissue structure. For example, the tissue is cartilage and,
prior to the inserting, the first region is separated from the
second region by a tear in the cartilage.
[0014] Alternatively, the first tissue is soft tissue and the
second tissue is bone.
[0015] Another aspect of the invention features a method for making
a tissue fastener comprising providing a shaft having a member
disposed thereon for lodging the shaft within the tissue, and a
tissue engaging head disposed at a proximal end of the shaft, and
making a region of the shaft relatively flexible to render the head
movable with respect to the shaft.
[0016] Preferred embodiments include making the tissue fastener so
as to have the structural features discussed above.
[0017] The flexibility of the tissue fastener allows the head to
move (either from side to side or up and down) in response to loads
imposed by the tissue, without compromising the security of the
tissue attachment. As a result, healing is promoted even in high
stress applications, with little risk of the head digging into, and
potentially damaging, the tissue. The tissue fastener is
particularly (but by no means exclusively) useful in the treatment
of shoulder and knee instability, and in small joint repairs. These
applications include meniscal repair, rotator cuff repair, Bankhart
procedures, and treatment of "slap" lesions.
[0018] Other features and advantages of the invention will become
apparent from the following description, and from the claims.
DRAWINGS
[0019] FIGS. 1 and 2 show a tissue fastener.
[0020] FIGS. 3-5 show the tissue fastener of FIG. 1 with an
insertion tool.
[0021] FIGS. 6A and 6B show the use of the tissue fastener of FIG.
1 to repair a tear in soft tissue.
[0022] FIGS. 7A and 7B show the use of the tissue fastener of FIG.
1 to attach soft tissue to bone tissue.
[0023] FIGS. 8 and 9 illustrate alternative embodiments of a tissue
fastener.
DESCRIPTION OF EMBODIMENTS
[0024] FIGS. 1 and 2 show one embodiment of a flexible tissue
fastener 10 that includes a flexible shaft 12 and a generally rigid
tip 14 and head 16 mounted at opposite ends of shaft 12. A pair of
generally rigid barbs 18 extend from tip 14 for anchoring fastener
in place within tissue. Shaft 12, tip 14, and head 16 are hollow
and have open-ended passages which are in communication along a
longitudinal axis 20 of fastener 10 for purposes to be
described.
[0025] Shaft 12 comprises a woven polymeric mesh 20 made from a
bioabsorbable polymer, preferably polylactic acid (PLA), that
defines an interior passage 22 open at both its proximal and distal
ends. The woven nature of mesh 20 renders shaft 12 flexible both
transversely to and along longitudinal axis 20. Thus, when fastener
10 is in vivo, shaft 12 can flex from side to side with respect to
axis 20 as the tissue applies shear forces to shaft 12 or head 16,
thereby avoiding tearing of the tissue that might otherwise occur
if shaft 12 was immobile. Additionally, shaft 12 can flex to allow
head 18 to lie flush with the tissue after insertion in
applications in which fastener 10 is not inserted perpendicularly
to the tissue surface. Thus, fastener 10 is less obtrusive in vivo
than rigid fasteners, and is less prone to damage either the tissue
being fastened or surrounding tissue.
[0026] The woven nature of mesh 20 also makes shaft 12 radially
compressible, allowing fastener 10 to be even less obtrusive when
subject to compressive forces that may be encountered when fastener
is used to attached soft tissue to other soft tissue. An example of
such an application is the use of fastener 10 to repair meniscal
tissue (i.e., cartilage) tears.
[0027] Mesh 20 further also provides structure and surface area for
insert molding tip 14 and head 16--which are preferably made from
polymeric material--onto shaft 12. Insert molding these features
14, 16 allows the polymeric material to melt around the fibers of
the mesh and mechanically lock features 14, 16 to shaft 12 upon
cooling. A bioabsorbable material such as PLA is preferred for tip
14 (as well as barbs 18) and head 16, because PLA has a uniform
rate of absorbability. Features 14, 16 are further integrated with
woven mesh 20 by melting them into as well as around mesh 20.
[0028] Tip 14 is generally cylindrical and has an outer surface 24
from which barbs 18 radially extend. Tip 14 terminates at a flat,
annular distal surface 26 that defines an open end of a passage 28
which extends through tip 14 and communicates with the hollow
interior 22 of shaft 12. Passage 28 is sized to receive a K-wire to
assist in guiding fastener 10 to the correct location in the tissue
during emplacement (described below).
[0029] Barbs 18 are circumferentially spaced by 180 degrees around
tip exterior surface 24 (although two barbs 18 are shown, it will
be appreciated that more or fewer barbs 18 may be used, and that
barbs 18 may be unevenly spaced around tip 14). Each barb 18 has a
flat, inclined exterior surface 30 that slopes outwardly as barb 18
extends proximally. Barb 18 terminates at a proximal surface 32
oriented generally perpendicularly to axis 20. The junction of
surfaces 30, 32 defines a sharp edge 34 which lodges barb 18 within
tissue during use, as will be explained.
[0030] Head 16 includes an annular body 36 having a flat,
tissue-engaging underside 38 and a rounded upper surface 40. A
passage 42 extends through body 36, is aligned with the hollow
interior 13 of shaft 12 and tip passage 28, and is open at both
ends for receiving the K-wire during insertion. A pair of
diametrically opposed slots 44 extend through body 36 between
underside 38 and upper surface 40 for purposes to be described.
[0031] Body 36 is relatively thin to provide fastener 10 with a low
profile when the device in place in vivo. The outer diameter of
body 36 is approximately the same as (or slightly larger than) the
maximum radial dimension defined by barbs 18. Body 36 has a
substantially larger outer diameter than shaft 12, thereby enabling
head 16 to capture tissue beneath it in a tac-like fashion when
fastener 10 is emplaced, as will be described. The corners of body
36 are rounded at underside 38 and upper surface 40 to avoid tissue
damage when shaft 12 flexes from side to side in response to
movement of the tissue being tacked down by head 16.
[0032] Fastener 10 is manufactured by insert molding. More
specifically, a length of woven mesh 20 is cut to a specific length
for fastener 10 and is inserted over a core pin. The injection mold
then closes on the core pin and polymeric material is then molded
onto and around woven mesh 20. Fastener 10 has an overall length of
0.100-0.500 inch (of which approximately 0.060-0.300 inch
corresponds to the length of shaft 12 between tip 14 and head 16)
and a maximum width (defined by barbs 18 and the diameter of head
16) of 0.040-0.300 inch.
[0033] Referring also to FIGS. 3-5, an insertion tool 50 for
emplacing fastener 10 in tissue includes a hollow, elongated rod 52
with a handle 54 at its proximal end and a fastener mount 56 at its
distal end. Rod 52, handle 54, and mount 56 are hollow to
accommodate a K-wire 58 used to guide fastener 10 into place in the
body. Rod 52 is sufficiently narrow to pass through a conventional
cannula to the surgical site, and handle 54 is large enough to fit
comfortably in the user's hand.
[0034] Mount 56 includes a pair of diametrically opposed arms 60
which extend from the distal end of rod 52. The circumferential
spacing between arms 60 corresponds to that between barbs 18 and
slots 44 in head 16. Arms 60 terminate at flat barb engaging
surfaces 62. Fastener 10 is loaded onto insertion tool 50 by
aligning slots 44 in head 16 with arms 60, and sliding fastener 10
proximally over arms 60 until surfaces 62 abut barb proximal
surfaces 32.
[0035] Referring to FIGS. 6A and 6B, in use, fastener 10 is used to
repair torn meniscal tissue 70 (e.g., in the knee) as follows. As a
first step in repairing tear 72, the surgeon determines the proper
insertion site (or sites) 74 at which fastener 10 (or a plurality
of fasteners 10) are to be emplaced. A relatively small tear 72
like that shown in FIGS. 6A and 6B may be repaired using only one
fastener 10; multiple fasteners 10 may be needed to close larger
tears. Insertion site 74 is located on the proximal side 76 of tear
72 (but the distal side of the tear may be used instead as the
insertion site).
[0036] The surgeon then introduces K-wire 58 to the surgical site
through a cannula (not shown), and stabs the tip of K-wire 58 into
meniscal tissue at insertion site 74. The surgeon urges K-wire 58
distally until its tip spans tear 72 and becomes embedded in
meniscal tissue 78 located distally of tear 72. Next, the surgeon
attaches fastener 10 to mount 56 of insertion tool 50, as described
above, slides the assembly over the proximal end of K-wire 58, and
feeds the assembly over K-wire 58 to the surgical site.
[0037] Then, the surgeon holds K-wire 58 securely in place with one
hand, and pushes insertion tool 50 distally with the other. The
engagement between arms 60 and barbs 18, as well as the engagement
of the distal end of rod 52 against head upper surface 40, pushes
fastener 10 over K-wire 58. Fastener 10 thus enters insertion site
76 and passes through proximal meniscal tissue 76 and across tear
72. The sloped nature of barb surfaces 30 allow barbs 18 to
smoothly pass through the meniscal tissue in the distal direction
of movement.
[0038] The surgeon continues distally advancing fastener 10 to
slide tip 15 further over K-wire 58 and into meniscal tissue 78
distally of tear 72. As fastener 10 moves distally, underside 38 of
head 16 engages meniscal tissue 76 on the proximal side of the
tear. The enlarged diameter of head 16 relative to shaft keeps head
16 from passing through the puncture behind shaft 12. As a result,
head 16 urges proximal tissue 76 toward distal meniscal tissue 78
and gradually closes tear 72 as fastener 10 is advanced
distally.
[0039] When barbs 18 have fully entered distal meniscal tissue 78,
the tissue attempts to close against shaft 12. Thus, perpendicular
barb surfaces 32 (FIG. 1) and edges 34 securely engage the meniscal
tissue, and firmly lodge tip 14 in place therein. Tear 72 is now
closed (FIG. 6B), and the surgeon withdraws insertion tool 50 and
K-wire 58. With the meniscal tissue 76, 78 on the two sides of the
tear held together by fastener 10, healing can begin. Over time,
meniscal tissue 76, 78 will grow together, thereby permanently
closing tear 72. In embodiments in which the materials of fastener
10 are biodegradable, fastener 10 gradually dissolves.
[0040] FIGS. 7A and 7B show the use of fastener 10 to re-attach
soft tissue 90 to bone 92 (e.g., during the repair of a torn
rotator cuff). First, a hole 94 is formed in bone 92 at the desired
attachment site, e.g., by drilling. K-wire 58 is introduced to the
surgical site, punched through soft tissue 90 at the selected
attachment location, and positioned in hole 94 to serve as a guide
for fastener 10 and insertion tool 50. After fastener 10 is placed
on insertion tool mount 56 as discussed above, the assembly is
inserted over K-wire 58 and advanced to the surgical site. The
surgeon holds K-wire 58 with one hand, and urges insertion tool 50
distally with the other, thereby punching fastener 10 through soft
tissue 90 (FIG. 7A).
[0041] The surgeon continues to advance insertion tool 50 distally
to insert fastener 10 into hole 94 (FIG. 7B). Barbs 18 lodge tip 14
securely within hole 9 by digging into the bone tissue (e.g., the
cancellous bone) around hole 94. As fastener 10 moves into hole 94,
underside 38 of fastener head 16 engages the upper surface of soft
tissue 90, thereby urging the soft tissue toward and against the
upper surface of bone 92. The enlarged nature of head 16 prevents
fastener 10 from passing completely through soft tissue 90 and
enabling fastener 10 to securely re-attach the tissue to the bone
in a tack-like manner. When fastener 10 has been fully inserted
into hole 94, the surgeon removes insertion tool 50 and K-wire
58.
[0042] Other embodiments are within the scope of the following
claims.
[0043] For example, other materials may be used for mesh 20 and the
generally rigid features (tip 14, head 16, and barbs 18). One
alternative material is polyglycolic acid (PGA), which is a
bioabsorbable material that degrades more rapidly in the body than
PLA. The tissue fastener may alternatively be made from
non-bioabsorbable material.
[0044] Barbs 18 may be located elsewhere on fastener 10, for
example on shaft 12. Barbs 18 may be blunt, rather than sharp. Tip
14 may be tapered or beveled distally; tip 14 may have a sharpened
distal edge to further facilitate insertion.
[0045] Other insertion tools may be employed. For example, the
insertion tool may be configured to engage the interior of tip 14
(e.g., a shoulder 29, FIG. 1, formed in the walls that define the
passage through tip 14). Alternatively, tip 14 may be solid.
[0046] Other kinds of flexible shafts are contemplated. Shaft 12
may comprise a braided or knitted mesh or comprise a non-mesh or
non-polymeric material. Shaft 12 may be solid rather than defining
a passage 22.
[0047] Shaft 12 may be rendered flexible in other ways. For
example, a generally rigid tissue fastener may be modified to
render it flexible at one or more places.
[0048] FIG. 8 shows a fastener 100 that has been so modified.
Fastener 100 is, e.g., a modified version of the Suretac.TM.
fastener, manufactured by Smith & Nephew, Inc. and described in
U.S. Pat. Nos. 5,100,417, 5,258,016, and 5,690,676, all of which
are incorporated herein by reference. Fastener 100 includes a
hollow shaft 102 that extends proximally from a distal end 104 to a
radially enlarged head 106. An interior passage 107 extends through
shaft 102 and is open at distal end 104 and head 106. Fastener 100
is formed by molding so that shaft 102 and head 106 define an
integral, unitary body.
[0049] A plurality of (e.g., three) axially spaced, circumferential
ribs 108 are disposed on shaft between end 104 and head 106. Ribs
108 have beveled leading (i.e., distal) surfaces to facilitate
advancement of fastener through tissue, and flat side and proximal
surfaces that lodge within the tissue.
[0050] Fastener 10 is made from polymeric material, such as the
aforementioned PLA. During fabrication, flexible material 110 is
embedded within the walls 112 of fastener 10, and shaft 102 is
relieved to provide a breakable connection 114 between shaft 102
and head 106. Connection 114 is preferably frangible (i.e., easily
breakable). This enables the rigid material of head 106 to break
free from that of shaft 102 in response to side-loading imposed by
the re-attached tissue, to reduce the risk of head 106 digging into
or otherwise damaging the tissue. Flexible material 110 tethers
head 106 to shaft 102, however, so that the tissue captured beneath
head 106 remains securely attached to the tissue (e.g., bone
tissue) into which shaft 102 has been inserted. In addition,
flexible material 110 reinforces the walls of shaft 102.
[0051] Flexible material 110 may have a wide variety of
configurations. For example, flexible material 110 may include
individual strands of material (such as man-made or natural fibers
or suture) or a flexible member such as a braided tube or braided
mesh. Suitable materials include PLA, PGA, polyester, cat gut,
polydioxanone, polypropylene, polyvinyl acetate, and natural
materials such as wool, silk, and cotton.
[0052] Flexible material 110 is insert molded into shaft 102 and
head 106 during the fabrication of fastener 10. Flexible material
110 preferably extends along the entire length of shaft 102, but
alternatively may terminate proximally of end 104. Flexible
material 110 is disposed uniformly around the circumference of
shaft 102 and head 106, although flexible material 110 may
alternatively be concentrated in, e.g., the segments of shaft 102
that are relieved. (Only one strand of flexible material 110 is
shown on each side of shaft 102 for simplicity.)
[0053] Shaft 102 may be relieved in a variety of ways, only two of
which--one or more rectangular holes 113 or one or more notches
113'--are shown. Shaft 102 may be relieved in as few or as many
places as are suitable to provide the frangible connection.
Preferably, shaft 102 is relieved in two diametrically opposed
locations, and the same type of relief (e.g., openings such as
holes 113 or notches 113') is used in each location. If
insufficient relief is provided, frangible connection 114 may not
break during use to achieve the desired flexibility. In contrast,
care should be taken not to excessively relieve shaft 102, or
frangible connection 114 may break during insertion of fastener 100
into tissue. As an alternative (or in addition) to openings 113,
113', shaft 102 may be relieved by making walls 112 relatively thin
in the region of connection 114.
[0054] In use to, e.g., re-attach soft tissue to bone (the
procedure shown in FIGS. 7A and 7B), fastener 110 is introduced to
the surgical site over a K-wire, and an insertion tool (not shown)
is advanced over the K-wire behind fastener 100. The insertion tool
has a sufficient outer diameter to engage the upper surface of head
106 around the opening of passage 107. Thus, as the surgeon
advances the insertion tool, he pushes shaft 102 through the soft
tissue and into the bone hole. Ribs 108 engage against the sides of
the bone hole to lodge fastener 100 in place, and head 106 captures
the soft tissue against the upper surface of the bone.
[0055] Thereafter, when side loads are placed on the soft tissue
(e.g., during movement by the patient), the side loads impose
sufficient force to break frangible connections 114, thereby
separating the rigid material of head 106 from that of shaft 102.
Head 106 continues to press the soft tissue against the bone,
however, due to the tethering provided by flexible material 100.
The flexible connection of head 106 to shaft 102 acts as a hinge
that allows head 106 to move from side to side (i.e., horizontally
with respect to shaft 102) in response to further side loads. This
avoids head 106 digging into, and perhaps damaging, the soft
tissue.
[0056] Other embodiments of a tethered fastener are possible. For
example, shaft 102 may be relieved after molding (such as by
cutting holes 113 or notches 113').
[0057] Referring to FIG. 9, fastener 200 is similar to fastener
100, except that teeth 202 protrude from the underside of the head
for more secure tissue attachment. Flexible material 110 is insert
molded within the walls of the shaft and head of fastener, and
shaft is relieved with holes (113) or notches (113') to provide the
frangible connection.
[0058] Still other embodiments are within the scope of the
claims.
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