U.S. patent application number 10/012416 was filed with the patent office on 2002-04-11 for graft anchor.
This patent application is currently assigned to Smith & Nephew, Inc., a Delaware Corporation. Invention is credited to Blough, Rebecca A., Brown, Charles H. JR., Ferragamo, Michael c., Graf, Ben K..
Application Number | 20020042615 10/012416 |
Document ID | / |
Family ID | 24412462 |
Filed Date | 2002-04-11 |
United States Patent
Application |
20020042615 |
Kind Code |
A1 |
Graf, Ben K. ; et
al. |
April 11, 2002 |
Graft anchor
Abstract
A graft anchor includes an anchor member for placement in bone
tissue. The anchor member defines an opening. An inner member is
insertably securable into the anchor member opening. A fastener is
configured such that insertion and securing of the inner member
into the anchor member opening results in a holding force being
applied to the graft. The anchor member is of limited length to
maintain its distal end within the bone. The anchor member includes
a distal drive opening for receiving a drive tool and the inner
member includes a proximal drive opening for receiving the drive
tool. The fastener includes channels for containing the graft, a
fastener body with protrusions extending from the fastener body for
penetrating bone tissue, and a reinforcing member contained within
the fastener body.
Inventors: |
Graf, Ben K.; (Madison,
WI) ; Ferragamo, Michael c.; (Norht Dighton, MA)
; Blough, Rebecca A.; (Warwick, RI) ; Brown,
Charles H. JR.; (Wellesley, MA) |
Correspondence
Address: |
JOEL PETROW
Smith & Nephew North America
1450 Brooks Road
Memphis
TN
38116
US
|
Assignee: |
Smith & Nephew, Inc., a
Delaware Corporation
|
Family ID: |
24412462 |
Appl. No.: |
10/012416 |
Filed: |
December 12, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10012416 |
Dec 12, 2001 |
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09541172 |
Apr 3, 2000 |
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09541172 |
Apr 3, 2000 |
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08800961 |
Feb 18, 1997 |
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08800961 |
Feb 18, 1997 |
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08602706 |
Feb 16, 1996 |
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Current U.S.
Class: |
606/312 ;
606/318; 606/323; 606/328; 623/13.14 |
Current CPC
Class: |
A61F 2/0805 20130101;
A61F 2002/0888 20130101; A61F 2/0811 20130101; A61F 2002/0852
20130101; A61F 2002/0858 20130101; A61F 2002/0835 20130101; A61F
2002/0829 20130101; A61F 2002/0882 20130101; A61F 2002/0864
20130101 |
Class at
Publication: |
606/73 ;
623/13.14 |
International
Class: |
A61B 017/86 |
Claims
What is claimed is:
1. A graft anchor comprising: an anchor member for placement in
bone tissue, said anchor member defining an opening, an inner
member insertable and securable into said anchor member opening,
and a fastener for applying a holding force to a graft, said
fastener being configured such that insertion and securing of said
inner member into said anchor member opening results in said
holding force being applied to said graft.
2. The graft anchor of claim 1 wherein said anchor member is of
limited length to maintain a distal end of the anchor member within
the bone.
3. The graft anchor of claim 1 wherein said anchor member opening
is a threaded axial bore.
4. The graft anchor of claim 3 wherein said axial bore includes a
distal drive opening for receiving a drive tool.
5. The graft anchor of claim 4 wherein said distal drive opening is
hexagonally shaped.
6. The graft anchor of claim 3 wherein said inner member includes
external threads for mating with said axial bore threads.
7. The graft anchor of claim 6 wherein said inner member includes a
smooth shank proximal of said external threads.
8. The graft anchor of claim 1 wherein said anchor member includes
external threads.
9. The graft anchor of claim 8 wherein said external threads are
self-tapping.
10. The graft anchor of claim 1 wherein said inner member includes
a proximal drive opening for receiving a drive tool.
11. The graft anchor of claim 10 wherein said proximal drive
opening is hexagonally shaped.
12. The graft anchor of claim 1 wherein said fastener includes a
channel for substantially containing the graft.
13. The graft anchor of claim 12 wherein said fastener includes a
guide defining said channel.
14. The graft anchor of claim 1 wherein said fastener includes a
plurality of channels for substantially containing the graft.
15. The graft anchor of claim 1 wherein said fastener includes a
fastener body and at least one protrusion extending from said
fastener body for penetrating bone tissue.
16. The graft anchor of claim 15 further including a plurality of
protrusions.
17. The graft anchor of claim 15 wherein said fastener further
includes a reinforcing member contained within said fastener body,
said fastener body having a strength less than said reinforcing
member.
18. The graft anchor of claim 1 wherein said fastener defines a
through bore.
19. The graft anchor of claim 18 wherein said fastener includes a
lip surrounding said through bore which separates the graft from
said through bore.
20. The graft anchor of claim 1 wherein said fastener body has a
generally circular shape.
21. The graft anchor of claim 20 wherein said fastener body
includes two flat sides.
22. A graft anchor comprising: an anchor member for placement in
bone tissue, said anchor member being of limited length to maintain
a distal end of the anchor member within the bone, said anchor
member comprising an axial bore having an internal threaded section
and a distal drive opening for receiving a drive tool, said anchor
member further having external, self-tapping threads, an inner
member having external threads and a proximal drive opening for
receiving said drive tool, said inner member being threadedly
insertable and securable in said anchor member axial bore, and a
fastener for applying a holding force to a graft, said fastener
including a fastener body and at least one protrusion extending
from said fastener body for penetrating bone tissue, said fastener
body defining a protective channel for containing the graft, said
fastener being configured such that insertion and securing of said
inner member through a central bore of said fastener and into said
anchor member opening results in said holding force being applied
to said graft.
23. A graft anchor comprising: an anchor member for placement in
bone tissue, said anchor member defining an opening, an inner
member insertable into said anchor member opening, and a fastener
for applying a holding force to a graft, said fastener including a
protective channel for containing the graft, said fastener being
configured such that insertion and securing of said inner member in
said anchor member opening results in said holding force being
applied to said graft.
24. A graft fastener, comprising: a fastener body defining a
protective graft channel for containing a graft, and at least one
protrusion extending from said fastener body for penetrating bone
tissue.
25. The graft fastener of claim 24 wherein said fastener body
defines a plurality of graft channels.
26. The graft fastener of claim 24 wherein said fastener body has a
through bore.
27. An anchor member, comprising: a body defining an axial bore,
said axial bore including a threaded section and a distal opening
for mating with a driver.
28. The anchor member of claim 27 wherein said distal opening is
hexagonally shaped.
29. A method of securing a graft to bone, comprising the steps of:
placing an anchor member into the bone, positioning a fastener such
that a portion of the graft lies between the fastener and the bone,
inserting and securing an inner member into the anchor member, the
insertion forcing the fastener into the bone to secure the graft by
squeezing the graft between the fastener and the bone.
30. The method of claim 29 further comprising the steps of:
drilling a bone tunnel, drilling a counterbore in the tunnel
perpendicular to a central axis of the tunnel, and drilling a hole
perpendicular to the central axis of the tunnel and centered within
the counterbore, placement of said anchor member into the bone
comprises the step of screwing the anchor member into the hole.
31. The method of claim 30 wherein said anchor member is
self-tapped into the hole.
32. The method of claim 29 wherein said anchor member is of limited
length such that placement of said anchor member into the bone
results in a distal end of the anchor member being maintained
within the bone.
33. The method of claim 29 wherein the portion of the graft that
lies between the fastener and the bone is contained within a
protective channel defined by the fastener.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of application Ser. No.
08/602,706 filed Feb. 16, 1996.
BACKGROUND OF THE INVENTION
[0002] The invention relates to an apparatus and method for
securing a graft to bone.
[0003] Reconstruction of the anterior cruciate ligament (ACL)
generally involves the placement of a tendon graft through a tibial
tunnel and securing the graft at one end to the femur and at the
other end to the tibia. It is known to secure the graft to the
tibia using staples, a bicortical screw and a fastening washer
having spikes for penetration into the bone, or a suture attached
to a fixation post embedded into the bone.
SUMMARY OF THE INVENTION
[0004] A graft anchor for securing a graft to bone includes an
anchor member for placement in bone tissue. The anchor member
defines an opening. An inner member is insertably securable into
the anchor member opening. A fastener is configured such that
insertion and securing of the inner member into the anchor member
opening results in a holding force being applied to the graft.
[0005] In particular embodiments of the invention, the anchor
member is of limited length to maintain its distal end within the
bone and the opening is a threaded axial bore. The inner member
includes external threads for mating with the axial bore threads
and a smooth shank proximal of the external threads. The anchor
member includes external, threads; the threads are preferably
self-tapping. The axial bore of the anchor member includes a distal
drive opening for receiving a drive tool, and the inner member
includes a proximal drive opening for receiving a drive tool. The
distal and proximal drive openings are preferably hexagonally
shaped. The fastener includes a channel for containing the graft, a
guide defining the channel, a fastener body with protrusions
extending from the fastener body for penetrating bone tissue, and a
reinforcing member contained within the fastener body. The fastener
body has a strength less than the reinforcing member. The fastener
includes a through bore and a lip surrounding the through bore
which separates the graft from the through bore. The fastener body
has a generally circular shape which may include two flat
sides.
[0006] According to another aspect of the invention, a method of
securing a graft to bone includes the steps of placing an anchor
member into the bone, positioning a fastener such that a portion of
the graft lies between the fastener and the bone, inserting and
securing an inner member into the anchor member, the insertion
forcing the fastener into the bone to secure the graft by squeezing
the graft between the fastener and the bone.
[0007] In particular embodiments of the invention, the method
includes drilling a counterbore in the tunnel perpendicular to a
central axis of the tunnel, and drilling a hole perpendicular to
the central axis of the tunnel and centered within the counterbore.
Placement of the anchor member into the bone is by screwing the
anchor member into the hole. The anchor member is self-tapped into
the hole. The anchor member is of limited length such that
placement of the anchor member into the bone results in a distal
end of the anchor member being maintained within the bone. The
portion of the graft that lies between the fastener and the bone is
contained within a protective channel defined by the fastener.
[0008] Advantages of the invention include the low profile
presented by the graft anchor because of its placement in a
counterbore. The placement of the graft anchor within a counterbore
creates a tortuous path for the graft to follow which produces
stronger initial fixation of the graft to the bone because of the
increased surface area between the graft and the bone. The
placement of the graft anchor within the bone tunnel eliminates any
protrusion of the graft anchor from the surface of the bone. The
fastener lip shields the graft from possible damage from the act of
inserting the screw into the anchor member. The smooth shank of the
inner member does not cut the graft. The containment of the graft
substantially within the fastener channels causes the graft to lie
flat against the bone increasing the area of contact between the
graft and the bone which increases the ability of the graft to heal
back to the bone. The anchor member has a larger outer diameter
than conventional bone anchors which increases the pull out
strength of the graft anchor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Other objects, features and advantages of the invention will
be apparent from the following description taken together with the
drawings in which:
[0010] FIG. 1 shows a graft anchor according to the invention
securing a graft to bone;
[0011] FIG. 2 is a partially cut away side view of an anchor member
of the graft anchor;
[0012] FIG. 2A is an end view of the anchor member of FIG. 2, taken
along lines 2A-2A;
[0013] FIG. 3 is a partially cut away side view of a screw of the
graft anchor;
[0014] FIG. 3A is an end view of the screw of FIG. 3, taken along
lines 3A-3A;
[0015] FIG. 4 is a side view of a fastener of the graft anchor;
[0016] FIG. 4A is an end view of the fastener of FIG. 4, taken
along lines 4A-4A, showing the graft in place against the
fastener;
[0017] FIGS. 5-5D illustrate how the graft anchor is inserted into
bone;
[0018] FIG. 6 is an end view of an alternative embodiment of a
fastener;
[0019] FIG. 7 shows a graft anchor including the fastener of FIG. 6
securing a graft to bone;
[0020] FIG. 8 is an end view of an additional alternative
embodiment of a fastener; and
[0021] FIGS. 9 and 9A show an alternative placement of the graft
anchor of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] Referring to FIGS. 1, 2, and 2A a graft anchor 10 for
securing a graft 2 to bone 4 has an anchor member 12, a fastener
14, and a screw 16. Anchor member 12 is made from, for example, a
titanium alloy, and has external threads 20 with flutes 21 to allow
passage of debris during self-tapping of the anchor member, and a
bore 22 having a threaded portion 24 and a distal hexagonal opening
26.
[0023] Referring to FIGS. 3 and 3A, screw 16 is made from, for
example, a titanium alloy, and includes a rounded distal end 30, a
threaded portion 32 for threaded engagement with threaded portion
24 of anchor member 12, a smooth shank 35 proximal of threaded
portion 32, and a proximal hexagonal opening 34.
[0024] Referring now to FIGS. 4 and 4A, fastener 14 in the
illustrated embodiment of the invention, has spikes 40, a through
bore 42, and guides 44 and 46 and a lip 48 which define two graft
receiving channels 50 and 52. An inner strengthening ring 54 is
made from, for example, a titanium alloy, while the remaining body
56 of fastener 14, which houses the strengthening ring is made from
a material exhibiting less strength, for example, polyacetal,
available from M. Holland Co., Northbrook, Ill.
[0025] Referring to FIGS. 5-5D, in use, graft anchor 10 is
preferably placed within a counterbore 62 oriented perpendicular
to, for example, a 9 mm bone tunnel 60. Counterbore 62 is drilled
with, for example, a 13mm flat bottom drill 61. Referring
particularly to FIG. 5A, a hole 63 is then drilled into the bone,
perpendicular to bone tunnel 60, and centered within counterbore
62. A drill guide 57 and a drill 58 having a shoulder 59 are used
to center hole 63 within counterbore 62 and to drill hole 63 to the
desired depth. In the illustrated embodiment the desired depth of
the hole is about 1.7".
[0026] Anchor member 12 is then screwed, self-tapped, into hole 63
with a drive tool 80 (FIG. 5B) having a hex end 82 that mates with
hex opening 26 of anchor member 12. The anchor member is advanced
into the bone until it lies flush or slightly below the surface of
the bone. Though the anchor member can extend bicortically, it need
not extend bicortically to provide adequate fixation. With the
distal end 83 of anchor member 12 lying within cancellous bone,
there is no protrusion of the graft anchor out the far side of the
bone which could cause irritation. Whereas bicortical screws come
in multiple sizes and the surgeon must size the screw to the
particular patient, graft anchor 10 is substantially a one-size
fits all system which speeds up the time of insertion.
Additionally, if distal end 83 of anchor member 12 is to lie in
cancellous bone, during the insertion of anchor member 12 into the
bone the surgeon does not need to align the anchor member to find
the far cortex.
[0027] Referring particularly to FIG. 5C, graft 2 is then fed
through bone tunnel 60 and fastener 14 is placed over the graft
with the graft substantially positioned in channels 50 and 52.
Graft 2 is crossed within fastener 14 (see FIG. 4A) which further
secures the graft within the channels. Graft 2 may partially extend
under spikes 40. Hex end 82 of drive tool 80 is then positioned in
hex opening 34 in screw 16 with screw 16 held by fingers 84 of
drive tool 80. Screw 16 is then placed through bore 42 of fastener
14 and is advanced into threaded bore 22 of anchor member 12 by
rotation of drive tool 80. The rounded distal end 30 of screw 16
aids in placement of the screw into bores 22 and 42. Lip 48 of
fastener 14 separates graft 2 from screw 16 protecting the graft
from possible damage resulting from being caught in the threads of
the screw.
[0028] After initial engagement of the screw with anchor member 12,
fingers 84 can be retracted (see FIG. 5D) to allow the screw to be
further advanced. Tightening of screw 16 into anchor member 12
forces spikes 40 of fastener 14 into bone 4 and squeezes graft 2
between the fastener and the surface of the bone, thus securing the
graft to the bone. Smooth shank 35 of screw 16 further protects
graft 2 from damage during tightening of the screw.
[0029] Referring to FIGS. 6 and 7, to facilitate placement of a
fastener within counterbore 62 located in bone tunnel 60, a
preferred spiked fastener 114 including flat sides 116 and 118 can
be used with anchor member 12 and screw 16. Fastener 114 includes
spikes 140, guides 144 and 146, lip 148, and channels 150 and 152.
The flat sides of fastener 114 aid in aligning the fastener with
graft 2 and in guiding the graft into channels 50 and 52 in the
area of limited access in tunnel 60. Additionally, with spiked
fastener 114 placed in counterbore 62, a force, in addition to the
one created by squeezing graft 2 between fastener 114 and surface
120 of counterbore 62, is applied to graft 2 by the squeezing of
the graft between the flat sides 116 and 118 of the washer and the
sides 122 and 124 of counterbore 62. This additional force aids in
securing graft 2 to the bone.
[0030] Referring to FIG. 8, to facilitate placement of a fastener
within bone tunnel 60 and particularly useful when hole 63 does not
include a counterbore, a fastener 214 including flat sides 215 and
216 is are positioned within tunnel 60 such that flat sides 215 and
216 run along the direction of the walls 218 of bone tunnel 60.
Fastener 214 includes spikes 240, guides 244 and 246, lip 248, and
channels 250 and 252. Fastener 214, having a longer dimension along
the x axis than the y axis, increases the area of contact between
graft 2 and the bone as compared to a fastener having a circular
profile. Flat sides 215 and 216 also align fastener 214 with the
long axis of bone tunnel 60 as the fastener is placed in the bone
hole which helps align graft 2 within channels 250 and 252.
[0031] Referring to FIGS. 9 and 9A, in an alternative placement of
graft anchor 10, hole 63a for placement of the graft anchor is
drilled through bone surface 90. Graft anchor 10 is then used to
anchor graft 2 to the bone, as described previously. In this
configuration washer 14 is placed flush against bone surface 90,
not within a counterbore, because drilling of a counterbore would
remove additional cortical layer of the bone weakening the
bone.
[0032] In addition to ACL repair, the graft anchor can be used in
other soft tissue fixation applications such as medial collateral
ligament (MCL) repair where the graft runs along the external
surface of the bones from the tibia to the femur and may be
anchored at one or both ends using graft anchor 10.
[0033] Additions, subtractions and other modifications of the
illustrated embodiments of the invention will be apparent to those
practiced in the art and are within the scope of the following
claims.
* * * * *