U.S. patent application number 10/431621 was filed with the patent office on 2003-10-16 for method and apparatus for attaching connective tissues to bone using a suture anchoring device.
This patent application is currently assigned to Opus Medical, Inc.. Invention is credited to Foerster, Seth A., Tran, Minh.
Application Number | 20030195564 10/431621 |
Document ID | / |
Family ID | 24470998 |
Filed Date | 2003-10-16 |
United States Patent
Application |
20030195564 |
Kind Code |
A1 |
Tran, Minh ; et al. |
October 16, 2003 |
Method and apparatus for attaching connective tissues to bone using
a suture anchoring device
Abstract
A bone anchor and methods for using same to secure connective
tissue, such as tendons, to bone are disclosed which permit a
suture attachment that lies entirely beneath the cortical bone
surface. The bone anchor of the invention incorporates a deformable
body that creates an increased anchor body diameter after it is
inserted into the cancellous bone and deployed beneath the cortical
surface of the bone. The increased body diameter, by virtue of its
intrinsic geometry, creates both axial and rotational fixation of
the bone anchor or suture fixation point.
Inventors: |
Tran, Minh; (Fountain
Valley, CA) ; Foerster, Seth A.; (San Clemente,
CA) |
Correspondence
Address: |
Donald E. Stout
Stout, Uxa, Buyan & Mullins, LLP
Suite 300
4 Venture
Irvine
CA
92618
US
|
Assignee: |
Opus Medical, Inc.
San Juan Capistrano
CA
|
Family ID: |
24470998 |
Appl. No.: |
10/431621 |
Filed: |
May 7, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10431621 |
May 7, 2003 |
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09616802 |
Jul 14, 2000 |
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6582453 |
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Current U.S.
Class: |
606/232 |
Current CPC
Class: |
A61B 2017/0438 20130101;
A61B 2017/00004 20130101; A61B 2090/037 20160201; A61B 2017/042
20130101; A61B 17/0401 20130101; A61B 2017/0458 20130101; A61B
2017/0412 20130101; A61B 2017/0414 20130101 |
Class at
Publication: |
606/232 |
International
Class: |
A61B 017/04 |
Claims
What is claimed is:
1. Apparatus for attaching connective tissue to bone, comprising a
shaft having a longitudinal axis, a proximal end, and a distal end,
which is adapted to be inserted into a bone, said shaft including a
plurality of spaced slits disposed about said periphery and having
an aperture disposed on said proximal end for receiving a suture,
said proximal end having a diameter which is no larger than a
diameter of said distal end.
2. The apparatus as recited in claim 1, wherein said proximal end
diameter is smaller than the distal end diameter.
3. The apparatus as recited in claim 1, wherein said shaft
comprises a peripheral wall bounding a lumen, said aperture being
disposed in said peripheral wall.
4. The apparatus as recited in claim 1, wherein said plurality of
spaced slits are generally parallel to said longitudinal axis.
5. The apparatus as recited in claim 1, wherein said plurality of
spaced slits each lie at an acute angle relative to said
longitudinal axis.
6. The apparatus as recited in claim 5, wherein said acute angle is
between 0 and 45 degrees.
7. The apparatus as recited in claim 1, wherein said plurality of
spaced slits comprises at least six slits.
8. The apparatus as recited in claim 5, wherein said plurality of
spaced slits is sufficient in number such that when an axial length
of said shaft is shortened, thereby causing a plurality of ribs
which are disposed between each of said plurality of slits to each
expand radially to form respective petals, each of said petals
overlap adjacent ones thereof.
9. The apparatus as recited in claim 3, and further comprising a
second aperture disposed on said peripheral wall in opposed
alignment with said first aperture, to thereby create a suture
conduit through the lumen of said shaft.
10. The apparatus as recited in claim 1, wherein said shaft is
cylindrical.
11. Apparatus for attaching connective tissue to bone, comprising a
shaft having a longitudinal axis, a proximal end, and a distal end,
which is adapted to be inserted into a bone, said shaft including a
plurality of spaced slits disposed about said periphery, said
apparatus being of a unitary construction and including no
structure which is disposed proximally of said shaft, the proximal
end of said shaft having a diameter which is not substantially
larger than a diameter of the distal end of said shaft, so that the
entire apparatus may be disposed within a hole in the bone to which
the connective tissue is to be attached.
12. The apparatus as recited in claim 11, and further comprising an
aperture disposed on said proximal shaft end for receiving a
suture.
13. The apparatus as recited in claim 11, wherein said proximal end
diameter is smaller than the distal end diameter.
14. The apparatus as recited in claim 12, wherein said shaft
comprises a peripheral wall bounding a lumen, said aperture being
disposed in said peripheral wall.
15. The apparatus as recited in claim 11, wherein said plurality of
spaced slits are generally parallel to said longitudinal axis.
16. The apparatus as recited in claim 11, wherein said plurality of
spaced slits each lie at an acute angle relative to said
longitudinal axis.
17. The apparatus as recited in claim 16, wherein said acute angle
is between 0 and 45 degrees.
18. The apparatus as recited in claim 11, wherein said plurality of
spaced slits comprises at least six slits.
19. The apparatus as recited in claim 16, wherein said plurality of
spaced slits is sufficient in number such that when an axial length
of said shaft is shortened, thereby causing a plurality of ribs
which are disposed between each of said plurality of slits to each
expand radially to form respective petals, each of said petals
overlap adjacent ones thereof.
20. Apparatus for attaching connective tissue to bone, comprising a
shaft having a longitudinal axis, a proximal end, and a distal end,
which is adapted to be inserted into a bone, said shaft including
at least six spaced slits disposed about said periphery and at
least six ribs, one of which is disposed between each pair of
spaced slits, wherein when an axial length of said shaft is
shortened, because of the application of a compressive force,
center portions of each of said ribs expand radially outwardly,
thereby each forming a petal, such that there are a plurality of
petals equal in number to the number of ribs.
21. The apparatus as recited in claim 20, wherein said plurality of
spaced slits each lie at an acute angle relative to said
longitudinal axis.
22. The apparatus as recited in claim 21, wherein said acute angle
is between 0 and 45 degrees.
23. The apparatus as recited in claim 21, wherein, when said ribs
are each in the radially expanded configuration, thereby forming
said petal, the formed petals overlap one another to create a
relatively strong structure for resisting axial pull-out
forces.
24. Apparatus for attaching connective tissue to bone, consisting
essentially of a shaft having a longitudinal axis, a proximal end,
and a distal end, which is adapted to be inserted into a bone, said
shaft including a plurality of spaced slits disposed about said
periphery, said shaft being of a unitary construction.
25. The apparatus as recited in claim 24, wherein the proximal end
of said shaft has a diameter which is not substantially larger than
a diameter of the distal end of said shaft, so that the entire
apparatus may be disposed within a hole in the bone to which the
connective tissue is to be attached.
26. A method of fabricating an apparatus for attaching connective
tissue to bone, comprising: making a flat pattern of a bone anchor
using a bio-compatible material; disposing a plurality of spaced
slits across a width of said flat pattern; and roll forming said
flat pattern into a generally cylindrical body.
27. The method as recited in claim 26, and further comprising a
step of forming a hole in said pattern at a proximal end
thereof.
28. The method as recited in claim 26, and further comprising a
step of forming two complementary notches in said pattern on
opposing sides thereof and at a proximal end thereof, prior to
completing said roll forming step.
29. The method as recited in claim 28, and further comprising a
step of forming a hole in said pattern in widthwise alignment with
each of said two complementary notches, prior to completing said
roll forming step.
30. The method as recited in claim 29, wherein said roll forming
step further comprises ensuring that said two complementary notches
are joined together to form an aperture once said cylindrical body
if formed, said aperture being in alignment with said hole to
create a suture channel through a lumen of said cylindrical
body.
31. The method as recited in claim 27, and further comprising a
step of coining said proximal end of the cylindrical body to form a
neck therein, on which is disposed said hole.
32. A method for securing connective tissue to bone, comprising:
creating a hole in said bone which extends distally beyond a
cortical surface thereof and into a cancellous portion thereof;
inserting an apparatus comprising a shaft having a plurality of
spaced slits disposed axially along a peripheral surface of the
shaft into said hole, so that no portion of the apparatus is
disposed above the hole; radially expanding a plurality of ribs
disposed between said spaced slits to thereby form an anchor
structure which is adapted to prevent axial pull-out of said
apparatus from said hole; and securing a suture to said apparatus
and to said connective tissue.
33. The method as recited in claim 32, wherein said radially
expanding step is performed by applying a compressive force axially
on said shaft, to shorten an axial length thereof.
34. The method as recited in claim 32, wherein said suture securing
step is performed prior to said radially expanding step.
35. The method as recited in claim 32, wherein said suture securing
step is performed after said radially expanding step.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to methods and apparatus
for attaching soft tissue to bone, and more particularly to anchors
and methods for securing connective tissue, such as ligaments or
tendons, to bone. The invention has particular application to
arthroscopic surgical techniques for reattaching the rotator cuff
to the humeral head, in order to repair the rotator cuff.
[0002] It is an increasingly common problem for tendons and other
soft, connective tissues to tear or to detach from associated bone.
One such type of tear or detachment is a "rotator cuff" tear,
wherein the supraspinatus tendon separates from the humerus,
causing pain and loss of ability to elevate and externally rotate
the arm. Complete separation can occur if the shoulder is subjected
to gross trauma, but typically, the tear begins as a small lesion,
especially in older patients.
[0003] To repair a torn rotator cuff, the typical course today is
to do so surgically, through a large incision. This approach is
presently taken in almost 99% of rotator cuff repair cases. There
are two types of open surgical approaches for repair of the rotator
cuff, one known as the "classic open" and the other as the
"mini-open". The classic open approach requires a large incision
and complete detachment of the deltoid muscle from the acromion to
facilitate exposure. The cuff is debrided to ensure suture
attachment to viable tissue and to create a reasonable edge
approximation. In addition, the humeral head is abraded or notched
at the proposed soft tissue to bone reattachment point, as healing
is enhanced on a raw bone surface. A series of small diameter
holes, referred to as "transosseous tunnels", are "punched" through
the bone laterally from the abraded or notched surface to a point
on the outside surface of the greater tuberosity, commonly a
distance of 2 to 3 cm. Finally, the cuff is sutured and secured to
the bone by pulling the suture ends through the transosseous
tunnels and tying them together using the bone between two
successive tunnels as a bridge, after which the deltoid muscle must
be surgically reattached to the acromion. Because of this maneuver,
the deltoid requires postoperative protection, thus retarding
rehabilitation and possibly resulting in residual weakness.
Complete rehabilitation takes approximately 9 to 12 months.
[0004] The mini-open technique, which represents the current
growing trend and the majority of all surgical repair procedures,
differs from the classic approach by gaining access through a
smaller incision and splitting rather than detaching the deltoid.
Additionally, this procedure is typically performed in conjunction
with arthroscopic acromial decompression. Once the deltoid is
split, it is retracted to expose the rotator cuff tear. As before,
the cuff is debrided, the humeral head is abraded, and the
so-called "transosseous tunnels", are "punched" through the bone or
suture anchors are inserted. Following the suturing of the rotator
cuff to the humeral head, the split deltoid is surgically
repaired.
[0005] Although the above described surgical techniques are the
current standard of care for rotator cuff repair, they are
associated with a great deal of patient discomfort and a lengthy
recovery time, ranging from at least four months to one year or
more. It is the above described manipulation of the deltoid muscle
together with the large skin incision that causes the majority of
patient discomfort and an increased recovery time.
[0006] Less invasive arthroscopic techniques are beginning to be
developed in an effort to address the shortcomings of open surgical
repair. Working through small trocar portals that minimize
disruption of the deltoid muscle, a few surgeons have been able to
reattach the rotator cuff using various bone anchor and suture
configurations. The rotator cuff is sutured intracorporeally and an
anchor is driven into bone at a location appropriate for repair.
Rather than thread the suture through transosseous tunnels which
are difficult or impossible to create arthroscopically using
current techniques, the repair is completed by tying the cuff down
against bone using the anchor and suture. Early results of less
invasive techniques are encouraging, with a substantial reduction
in both patient recovery time and discomfort. The major stumbling
block for many surgeons is the extreme difficulty in performing the
procedure with the currently available tools and techniques.
[0007] There are various bone anchor designs available for use by
an orthopedic surgeon for attachment of soft tissues to bone. The
basic commonality between the designs is that they create an
attachment point in the bone for a suture that may then be passed
through the soft tissues and tied, thereby immobilizing the soft
tissue. This attachment point may be accomplished by different
means. Screws are known for creating such attachments, but suffer
from a number of disadvantages, including their tendency to loosen
over time, requiring a second procedure to later remove them, and
their requirement for a relatively flat attachment geometry.
[0008] Another approach is to utilize the difference in density in
the cortical bone (the tough, dense outer layer of bone) and the
cancellous bone (the less dense, airy and somewhat vascular
interior of the bone). There is a clear demarcation between the
cortical bone and cancellous bone, where the cortical bone presents
a kind of hard shell over the less dense cancellous bone. In one
prior art approach that utilizes this physiological construct, the
anchor is designed so that it has a longer axis and a shorter axis
and is usually pre-threaded with suture. These designs use a hole
in the cortical bone through which an anchor is inserted. The hole
is drilled such that the shorter axis of the anchor will fit
through the diameter of the hole, with the longer axis of the
anchor being parallel to the axis of the drilled hole. After
deployment in to the cancellous bone, the anchor is rotated
90.degree. so that the long axis is aligned perpendicularly to the
axis of the hole. The suture is pulled, and the anchor is seated up
against the inside surface of the cortical layer of bone. Due to
the mismatch in the dimensions of the long axis of the anchor and
the hole diameter, the anchor cannot be retracted proximally from
the hole, thus providing resistance to pull-out.
[0009] Examples of such an approach are seen in U.S. Pat. No.
5,879,372 to Bartlett and U.S. Pat. No. 6,007,4567 to Bonutti.
Depending upon the density of the cancellous bone, these devices
may be somewhat difficult to deploy. If the cancellous bone density
is high, it is difficult to force the inserted anchor to rotated
into a secured position.
[0010] It is possible to utilize other anchor geometry to take
advantage of the cortical and cancellous bone interface. Various
methods of creating an expanded or tortuous frontal area beneath
the cortical surface have been described in the prior art. An
example of this approach is seen is U.S. Pat. No. 5,797,963 to
McDevitt. This patent describes a sub-cortical anchor that utilizes
a tapered flaring tool which deploys fingers circumferentially
disposed about the periphery of the anchor to engage the cancellous
bone and to resist retraction through the limited diameter hole in
the cortical bone. A similar approach is disclosed in U.S. Pat.
Nos. 5,690,649 and 6,022,373, both to Li. The Li patents describe
an anchor that incorporates two cylindrical halves with fingers
that are interdigitated. When a force is imposed on the two halves,
the interlocked fingers cause the deflection and deployment of the
concomitant adjacent fingers on the opposite half, creating the
expanded areas that resists pullout. In all of these designs, the
expanding mechanism is adapted to resist axial loading, but there
is no disclosure that they are capable of rotational fixation.
[0011] Still other prior art approaches have attempted to us a "pop
rivet" approach. This type of design requires a hole in the
cortical bone into which a split shaft is inserted. The split shaft
is hollow, and has a tapered plug leading into its inner lumen. The
tapered plug is extended out through the top of the shaft, and when
the plug is retracted into the inner lumen, the tapered portion
causes the split shaft to be flared outwardly, ostensibly locking
the device into the bone.
[0012] Other methods of securing soft tissue to bone are known in
the prior art, but are not presently considered to be feasible for
shoulder repair procedures, because of physicians' reluctance to
leave anything but a suture in the capsule area of the shoulder.
The reason for this is that staples, tacks, and the like could
possibly fall out and cause injury during movement. As a result of
this constraint, the attachment point often must be located at a
less than ideal position. Also, the tacks or staples require a
substantial hole in the soft tissue, and make it difficult for the
surgeon to precisely locate the soft tissue relative to the
bone.
[0013] By now it should be clear that many existing fastener
technologies have been adapted for use in creating an anchor point
for sutures in bone. Screws, pop rivets, and the like are certainly
adaptable to the wooden-like structure exhibited by bone. However,
as previously discussed, bone also incorporates a structure that
presents a hard, dense, outside surface and a softer, less dense
core. Because of this structure, another type of fastener, commonly
referred to as a "moly bolt" or "expandable bolt", may be adapted
for use in the bone. These types of fasteners were originally
designed for creating attachment points in plaster board walls
where the wall is analogous to the hard cortical bone surface and
the airspace or insulation space is analogous to the softer
cancellous bone.
[0014] One example of such a fastener is shown in U.S. Pat. No.
4,828,439, to Giannuzzi. A screw anchor is disclosed which includes
a four-legged compressible shank whose normal shape is
diamond-like, the front legs of the shank being joined together by
a front apex hinge and the rear legs being joined to the front legs
by side apex hinges. The rear legs terminate in feet whose adjacent
soles normally assume the form of an inverted V-inlet. A socket
whose bore lies in axial registration with a hole in the front apex
of the shank is secured by a pair of normally outstretched
resilient webs to the respective rear legs. To install the anchor,
its side apex hinges are manually compressed to collapse the shank
into a tongue which is then inserted through a hole drilled in the
wall until the socket is seated therein and the shank which is now
behind the wall resumes its diamond-like shape. Then a screw for
holding the fixture against the wall is inserted in the socket bore
and turned therein until its tip is intercepted by the inlet which
is dilated thereby to admit the screw. As the turning screw
continues to advance, its crests engage the soles of the feet to
force the rear legs apart and in doing so compels the shank to
assume a triangular shape. At the conclusion of the screw advance,
its tip is threadedly received in the hole of the front apex to
create behind the wall a triangular truss in which the screw forms
a central strut. It is clear in reference to this patent that the
principal fixation is axial, and that no provision for rotational
fixation is provided.
[0015] U.S. Pat. No. 5,893,850 to Cachia describes a fixation
device of a type useful for connecting two or more bone segments
during the healing process. In the preferred embodiment, the device
comprises an elongate pin having a distal anchor thereon. This
distal anchor is essentially an umbrella-shaped end to the pin that
may be selectively collapsed for pushing through a hole drilled
through the bone segments, and then deployed at the distal end of
the hole to prevent the elongate pin from retracting back through
the hole. A proximal anchor is co-axially and slidably disposed
with respect to the pin, and fixable to accommodate different bone
dimensions and permit appropriate tensioning of the fixation
device. An additional embodiment may be used when the preferred
embodiment is not possible to deploy. This situation may occur, for
example, when there is not a distal bone surface to allow for the
deployment of the umbrella-shaped pin end. This embodiment
describes a construction with multiple, axially expanding strips
that are configured to engage the cancellous bone to resist axial
withdrawal of the main body of the anchor. The patent describes two
or more sets of strips, as the disclosed function of the anchor is
to fixate at least two bone segments together to promote healing of
the bone. There is no mention of providing an anchor point to which
a suture may be secured, nor is one contemplated.
[0016] Still another bone fixation device of interest is disclosed
in U.S. Pat. No. 5,501,695 to Anspach, Jr. et al. In this patent,
there is disclosed a bone anchor apparatus which comprises a rivet
body having a lower annular portion 12 and an upper annular portion
100. The lower annular portion includes an outer surface formed as
an extension of the outer surface of the upper annular portion.
Because the thickness of the lower annular portion is less than
that of the upper annular portion, the upper annular portion acts
as an annular step or stop. A plurality of longitudinal slots are
formed on the outer surface of the lower annular portion, and
lengthwise ribs are formed between the slots. The apparatus
comprises multiple components, including, additionally, a separate
puller, including a head and a puller rod, which extends upwardly
through the inner diameter of the lower and upper parts of the
rivet's annular portions. In operation, the puller is actuated
upwardly until it strikes the annular step, thereby axially
compressing the lower annular portion so that the ribs are expanded
radially outwardly.
[0017] There is shown in FIG. 8 of the '695 patent a disk 38 which
includes apertures 40 for accommodating attachment of a suture 42
thereto. This disk, however, remains above the surface of the bone
once the anchor is in place. While the '695 patent discloses an
apparently functional device, it is complicated and difficult to
use in the close quarters attendant to arthroscopic procedures.
[0018] It may be seen, then, that as different fasteners have been
adapted for use in providing an anchor point for a surgical suture
in conjunction with attaching soft tissues to bone, various
problems and challenges have appeared. Although some of those
problems and challenges have been addressed, not all of the
requirements for simple, secure fixation have been met,
particularly for creating a simple and facile apparatus and method
for soft tissue fixation that may be deployed arthroscopically.
[0019] What is needed, therefore, is a new arthroscopic approach
for providing an anchor point in bone structure, wherein the anchor
resides completely below the superficial cortical bone surface,
provides both axial and rotational fixation, is better for the
patient, is uncomplicated to use, thereby saving time during the
repair procedure, and is easily mastered by properly skilled
personnel.
SUMMARY OF THE INVENTION
[0020] The present invention solves the problems outlined above by
providing an innovative bone anchor and connective techniques which
permit a suture attachment which lies entirely beneath the cortical
bone surface. The anchor design permits easy and facile insertion
into the bone, and simple and secure anchoring after
deployment.
[0021] More particularly, there is provided by the inventive
apparatus a means and method for attaching soft or connective
tissue to bone, comprising a hollow cylinder having a longitudinal
axis and a periphery which is adapted to be inserted into a hole
pre-drilled into bone. The cylinder is adapted to have a plurality
of slits and ribs running parallel to or roughly along the
longitudinal axis of the cylinder and equally distributed about the
diameter of the cylinder. For example, there may be 4 slits
defining 4 ribs, equally spaced at 90.degree. intervals around the
cylinder. These ribs are predisposed to bend in a direction
radially outwardly from their resting position when an axial load
is placed upon the cylinder. The ribs bend in a characteristic
fashion that has each end of the ribs bending outwardly, with the
center of the rib bending at an angle approximately twice that of
the ends, and in the opposite direction. Such structure creates a
"flower" or an expansion of the outside diameter of the cylinder.
The "flower" moniker is chosen because, as the ribs bend outwardly
away from the body of the cylinder, they create "petals" around the
periphery of the cylinder.
[0022] As previously mentioned, the structure of the bone in the
humerus, for example, has a dense outer layer called the cortical
bone, and a lacy, cellular inner structure called the cancellous
bone. When the hole for the present invention is drilled in the
bone, the hole extends through the cortical layer and into the
cancellous layer. As it may be seen, if the anchor is placed such
that the deployment of the ribs creating the flower is undertaken
below the cortical layer and in the cancellous layer, it is not
possible to remove the anchor proximally from the hole, as it is
trapped underneath the cortical layer. This provides an extremely
secure anchoring point that distributes any load placed upon it
over a relatively large surface area when compared to anchors known
in the prior art. This distribution of load is a significant
advance in the art, and allows loads that typically would surpass
the tensile strength of the sutures used to secure the tissues. In
other words, because of the innovative design of the anchor, the
sutures will break before the anchor is displaced.
[0023] In the present state of the art, as discussed supra, the
sutures which are passed through the tissues to be attached to bone
typically are threaded through a small eyelet incorporated into the
head of the anchor and then secured by tying knots in the sutures.
Although the anchor means herein described certainly are amenable
to such attachment, if desired, an eyelet is by no means the only
way that sutures may be secured to the bone anchor. Other means of
attachment which allow for adjustable, releasable suture fixation
that does not require knot tying is contemplated. One such method
and associated apparatus is described and disclosed in U.S. patent
application Ser. No. 09/475,495 entitled METHOD AND APPARATUS FOR
ATTACHING CONNECTIVE TISSUES TO BONE USING KNOTLESS SUTURE
ANCHORING DEVICE which is commonly assigned and incorporated in its
entirety herein by reference. In that patent application, a unique
new bone anchoring system is described that eliminates the need for
tying knots. The system includes a winch-like wrapping up of the
sutures attached to the soft tissues. Such an anchor embodiment has
the additional requirement of requiring angular or rotational
fixation along with axial fixation. It may be seen that the
geometry created by the present invention may provide both axial
and rotational means of fixation for the bone anchor. The petals of
the flower, as previously discussed, do prevent the anchor from
being pulled axially out through the hole through which it was
deployed. Also, because of the fact that the petals expand radially
outward from the body of the anchor, they create anchor points
within the cancellous bone that also resist rotational forces.
[0024] Additionally, the inventors have refined the "flower"
concept to incorporate a unique and advantageous modification to
the pattern of slits and ribs. By creating, in one preferred
embodiment, the slits and ribs on a bias (in other words, at an
acute angle when viewed relative to the axis of the body of the
anchor), a different deployment mechanism is effected. With
substantially axial ribs and slits, the ribs fold up in their
characteristic fashion as previously described, i.e. each end of
the ribs bending outwardly, with the center of the rib bending at
an angle twice that of the ends and in the opposite direction and
ultimately the two ends of the ribs flattening against each other.
Instead, when the ribs are formed on the aforementioned bias, they
tend to bend in a semi circular fashion and stack on top of each
other, forming overlapping petals that create a substantial bulge
in the body of the anchor.
[0025] More particularly, there is provided an apparatus for
attaching connective tissue to bone, which comprises a shaft having
a longitudinal axis, a proximal end, and a distal end. The shaft is
adapted to be inserted into a bone, and includes a plurality of
spaced slits disposed about the shaft periphery. Preferably, the
shaft comprises a peripheral (cylindrical) wall defining a central
lumen, and an aperture is disposed directly on the proximal end of
the shaft (specifically on the peripheral wall) for receiving a
suture. Unlike the prior art, the proximal end of the shaft, where
the aperture is disposed in the peripheral wall thereof, has a
diameter which is no larger (and preferably smaller) than a
diameter of said distal end. This unique configuration permits the
entire apparatus, including the suture anchoring point, to be
disposed within a hole drilled in the bone, so that no portion
thereof extends above the cortical bone surface.
[0026] In one embodiment, the plurality of spaced slits are
generally parallel to the longitudinal axis. In another preferred
embodiment, the plurality of spaced slits each lie at an acute
angle (preferably between 0 and 45 degrees) relative to the
longitudinal axis.
[0027] In a preferred embodiment, there is preferably a second
aperture disposed on the peripheral wall in opposed alignment with
the first aperture, to thereby create a suture conduit through the
lumen of the shaft.
[0028] In another aspect of the invention, there is disclosed an
apparatus for attaching connective tissue to bone, comprising a
shaft having a longitudinal axis, a proximal end, and a distal end,
which is adapted to be inserted into a bone. The inventive shaft or
tubular structure includes a plurality of spaced slits disposed
about the periphery thereof. The apparatus is of a unitary
construction and includes no structure which is disposed proximally
of the shaft. The proximal end of the shaft has a diameter which is
not substantially larger than a diameter of the distal end of the
shaft, so that the entire apparatus may be disposed within a hole
in the bone to which the connective tissue is to be attached.
[0029] In yet another aspect of the invention, an apparatus is
provided for attaching connective tissue to bone, comprising a
shaft having a longitudinal axis, a proximal end, and a distal end,
which is adapted to be inserted into a bone. Advantageously, the
inventive shaft includes at least six spaced slits disposed about
the periphery and at least six ribs, one of which is disposed
between each pair of spaced slits, wherein when an axial length of
the shaft is shortened, because of the application of a compressive
force, center portions of each of the ribs expand radially
outwardly, thereby each forming a petal, such that there are a
plurality of petals equal in number to the number of ribs. The
inventors have found that a minimum of six ribs is preferred in
order to provide the expanded anchor structure with adequate
rigidity to function effectively in resisting pullout forces
applied to the inventive anchor. In particular, in preferred
embodiments, the plurality of spaced slits each lie at an acute
angle (preferably 0 to 45 degrees) relative to the longitudinal
axis of the shaft.
[0030] In this embodiment, when the aforementioned petals are
created by radial expansion of the ribs, the inventors have found
that the formed petals should overlap one another. Six or more ribs
are preferred to assure this overlapping arrangement.
[0031] In still another aspect of the invention, there is provided
an apparatus for attaching connective tissue to bone, consisting
essentially of a shaft having a longitudinal axis, a proximal end,
and a distal end, which is adapted to be inserted into a bone. The
shaft includes a plurality of spaced slits disposed about its
periphery, and is of a unitary construction.
[0032] In another aspect of the invention, there is disclosed a
method of fabricating an apparatus for attaching connective tissue
to bone. This method comprises an initial step of making a flat
pattern of a bone anchor using a bio-compatible material. Then, a
plurality of spaced slits are disposed across a width of the flat
pattern. The flat pattern is then roll formed into a generally
cylindrical tubular body or shaft. In preferred approaches, a hole
is formed in the pattern at a proximal end thereof, prior to roll
forming. Additionally, the method preferably includes a step of
forming two complementary notches in the pattern on opposing sides
thereof and at a proximal end thereof. These two notches and the
aforementioned hole should be in widthwise alignment with one
another, so that when the structure is roll formed, they will
together form a pair of aligned holes that create a suture channel
through a lumen of the cylindrical body.
[0033] In yet another aspect of the invention, there is disclosed a
method for securing connective tissue to bone. The method comprises
a step of creating a hole in the bone which extends distally beyond
a cortical surface thereof and into a cancellous portion thereof.
Then, an apparatus comprising a shaft having a plurality of spaced
slits disposed axially along a peripheral surface thereof is
inserted into the hole, so that no portion of the apparatus is
disposed above the hole. A plurality of ribs disposed between the
spaced slits are then radially expanded to form an anchor structure
which is adapted to prevent axial pull-out of the apparatus from
the hole. A suture is secured to the apparatus and to the
connective tissue.
[0034] Preferably, the aforementioned radially expanding step is
performed by applying a compressive force axially on the shaft, to
shorten an axial length thereof. The suture securing step may be
performed prior to or after the radially expanding step.
[0035] The invention, together with additional features and
advantages thereof, may best be understood by reference to the
following description taken in conjunction with the accompanying
illustrative drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 illustrates a humerus and a tendon to be attached
thereto in cross-section;
[0037] FIG. 2A is a plan view of a flat pattern to be formed into a
bone anchor of the present invention;
[0038] FIG. 2B is a perspective view of the flat pattern
illustrated in FIG. 2A which has been roll formed into a
cylinder;
[0039] FIG. 3 is a perspective view of the structure illustrated in
FIG. 2B, coined into a bone anchor of the present invention;
[0040] FIG. 4 is a perspective view of the bone anchor of FIG. 3
after deployment in accordance with a method of the present
invention;
[0041] FIG. 5 is a cross-sectional view showing the bone anchor of
FIG. 3 inserted into a hole drilled into the humerus of FIG. 1,
according to a method of the present invention;
[0042] FIG. 6 is a cross-sectional view of the bone anchor of FIG.
5 after it has been deployed;
[0043] FIG. 6A is a perspective view of an alternative application
for the bone anchor of the present invention;
[0044] FIG. 7 is a perspective view of an alternative embodiment of
the bone anchor of the present invention;
[0045] FIG. 8 is a perspective view of the bone anchor of FIG. 7 in
a deployed state;
[0046] FIG. 9 is a cross-sectional plan view of a humerus and
tendon showing the anchor of FIG. 7 inserted into the humerus of
FIG. 1, in accordance with a method of the present invention;
and
[0047] FIG. 10 is a cross-sectional plan view similar to FIG. 9,
showing the anchor in a deployed state and the tendon sutured to
the humeral bone.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0048] Referring now more particularly to the drawings, there is
shown in FIG. 1 a partial cross-sectional view of a humeral head 10
which includes an outer surface of cortical bone 12 and inner
cancellous bone 14. A rotator cuff tendon 16 is disposed across the
surface of the cortical bone 12. A blind hole 18 has been made,
preferably by drilling, through a desired location on the cortical
bone 12 and into the cancellous bone 14. This illustration is
intended to provide a simple overview of the physiological elements
and structure involved in a typical situation wherein reattachment
of connective tissue such as the tendon 16 to the cortical bone 12
is desired. It is to be understood that the proximity in the
illustration of the rotator cuff tendon 16 to the cortical bone 12
is merely exemplary, and that the rotator cuff tendon 16 is not
attached to the cortical bone 12 at the interface 20 between the
two.
[0049] Referring now to FIG. 2A, there is illustrated a flat
pattern 22 of a bone anchor constructed in accordance with the
principles of the present invention, including slits 24 and ribs 26
which are formed by the pattern of slits 24, together with a hole
28 and half holes 30a, 30b, aligned across the width of the pattern
22 at one end thereof. Such flat pattern 22 may be fabricated from
any material suitable for implantation into the body as is known in
the art, such as stainless steel 316L, and may be formed by flat
stamping or photochemical machining or the like.
[0050] Referring to FIG. 2B, the flat pattern 22 has been roll
formed into a cylindrical body 32, which includes the slits 24 and
ribs 26 seen in FIG. 2A, as well as the hole 28, and the half holes
30 which are now formed into a single hole 34, as a result of the
roll forming process. It is to be understood, of course, that the
flat form of the anchor has been shown for informational purposes
as to one possible method of fabrication, and is not to be deemed
limiting. Clearly, to those skilled in the art, many other methods
of manufacture, such as laser cutting drawn hypodermic tubing, or
deep draw progressive die stamping, may be employed.
[0051] FIG. 3 shows the cylindrical body 32 of FIG. 2B, but it has
now been coined to form a neck 36 at a proximal end 38, such that
the hole 28 and the single hole 34 are aligned with each other to
form a conduit 40 for suture to be passed through, to thereby
provide an anchor point for the suture. How this anchor point is
used will be more fully described below in connection with
subsequent drawing figures.
[0052] The bone anchor of FIG. 3 is shown in its undeployed state.
Referring, however, to FIG. 4, it may be seen that the geometry of
the ribs 26 has now been changed such that the ribs 26 have been
bent to form one petal 44 that includes roots 46a,b and an apex 48.
It is to be understood that although this description of the petal
44 is singular, it is clear that the geometry and configuration of
the anchor includes multiple petals, and that this description
therefore is applicable to all of the petals. In fact, in preferred
embodiments a minimum of five petals, comprising, of course, six
ribs and six associated slits, are employed, for reasons to be
discussed hereinbelow.
[0053] The deformation of the ribs 26 is accomplished by imposing a
compressive force on the distal end 42 and the proximal end 38 of
the cylindrical body 32. Because each of the ribs 26 act as an
independent column, when the compressive force is imposed, they
eventually bend as a result of column buckling. After the onset of
such buckling, the characteristic geometry has an angle of buckling
at the apex 48 of the petal 44 which is equal to the sum of the
angles at the roots 46 a,b. At the formation of the petals 44,
interstices 50 are created between the petals 44. The interstices
50 are important to the creation of a rotational fixation moment,
in that edges 52 of the petals 44 are in direct contact with the
cancellous bone as the flower is formed. The apex 48 creates a
channel in the cancellous bone that traps material in the
interstices 50 of the flower. Any rotational moment imposed on the
bone anchor is resisted by the petals 44, and specifically by the
edges 52 of the petals 44.
[0054] Referring to FIGS. 5 and 6, it can be seen how the inventive
apparatus can be used as a bone anchor for attachment of soft
tissues to bone. FIG. 5 illustrates a bone anchor 54 of the type
shown in FIGS. 2-4 that has been inserted into the drilled hole 18
in the humeral head 10. The bone anchor 54 includes slits 24 and
ribs 26 on a cylindrical body 32, as previously described. A length
of suture 56 has been passed through the conduit 40 at the proximal
end 38 of the bone anchor 54, and then through the soft tissue
represented by the rotator cuff tendon 16. After insertion into the
drilled hole 18, the slits 24 and ribs 26 are in position in the
cancellous bone 14 and below the surface of the cortical bone
12.
[0055] Now referring particularly to FIG. 6, the bone anchor 54 is
illustrated in its deployed state. The slits 24 and ribs 26 have
been converted into petals 44, and the apex 48 of each petal 44 has
dug its way into the cancellous bone 14. The petals create a large
surface area that bears against the underside of the cortical bone
12, and prevents the bone anchor 24 from being retracted proximally
out of the drilled hole 18 in the cortical bone 12. The suture 56
has been tied into a knot 58, which pulls the rotator cuff tendon
16 down against the cortical bone 12.
[0056] As previously described, the inventive anchor fixation
structure may be used not only to provide axial fixation, but also
rotational fixation. Referring now to FIG. 6A, it can be seen how
the petals 44 may create a rotational fixation structure. As
previously noted, the contents of commonly assigned U.S. patent
application Ser. No. 09/475,495 have been incorporated in their
entirety in the present application. In that application, there is
disclosed a unique bone anchoring system which utilizes an anchor
structure that mimics a winch in order to create the fixation point
and create tension in the sutures that are disposed through the
tendon or soft tissue to be attached to bone. This novel system has
the additional structural requirement of rotational fixation, as
the suture is wrapped around the anchor body to create the
aforementioned fixation and tension.
[0057] Accordingly, in FIG. 6A there is shown a bone anchor 60
which includes an anchor body 62 and petals 64. The bone anchor is
inserted into a drilled hole 66 in the bone through cortical bone
68 and into cancellous bone 70. A suture 72 is passed through a
tendon 74, threaded through a slit 76 in the bone, and is wrapped
around the anchor body 62 by rotation of the anchor body 62. As
previously discussed, the formation of the petals 64 create
interstices 78 in the cancellous bone 70, which in turn provides a
rotational moment about the axis of the anchor body 62. The created
rotational moment resists any rotational force imposed by the
suture 72 on the anchor body 62. it is important to note that this
anti-rotational structure is deliberately created by judicious
selection of petal geometry, i.e. the number of petals, how far
they extend from the body 62, the breadth of their shoulders, and
the thickness of the material from which they are fabricated. These
factors affect the size and shape of the interstices that are
formed between the petals, and, of course, the concomitant
rotational moment that may be developed thereby.
[0058] More particularly, the inventors have found that a minimum
of six ribs, forming six petals, are preferably employed, in order
to ensure that the interstices between expanded ribs are not too
large to be effective in containing trapped cancellous bone
material, which functions in resisting applied rotational forces. A
greater number of petals are also preferred to provide adequate
expanded surface area to resist any applied rotational forces, as
well as to provide a sufficiently strong expanded structure to
adequately resist applied pullout forces. On the other hand, too
many ribs, and consequent petals, will result in interstices which
are too small to effectively trap an adequate amount of cancellous
bone material.
[0059] Another embodiment of the present invention may be seen by
referring to FIG. 7, where there is illustrated a bone anchor 80
which includes a cylindrical body 82, into which slits 84 have been
formed, creating ribs 86. The bone anchor 80 also includes a
proximal end 88, a distal end 90, and a suture conduit 92. As may
be observed from FIG. 7, the slits 84 have been formed at an acute
angle (i.e. between 0 and 90 degrees, and preferably less than 45
degrees) to the axis of the cylindrical body 82. As before, it is
to be understood that in referring to a single slit 84 or rib 86,
we are also referring to the multiplicity of slits 84 and ribs 86
that are formed in the cylindrical body 82, as a single slit 84 or
rib 86 is representative of each of the slits 84 or ribs 86. In
other words, each petal has the same geometry and physical
behavior, though the precise number of slits and ribs may vary in
different embodiments, without deviating from the overall inventive
concept. It may also be observed that the materials and
construction of this embodiment of the bone anchor may be chosen
using criteria similar to those described earlier with respect to
alternate embodiments.
[0060] As may be seen by referring now to FIG. 8, as a compressive
force is impressed on the distal end 90 and the proximal end 88,
the ribs 86 buckle and deform into the characteristic shape shown.
Because of the bias cut on the slits 84, instead of buckling in a
linear fashion like the ribs 26 of FIG. 6, the ribs 86 buckle such
that they take on a semi-circular shape, and adjacent ribs overlap
and support each other. The inventors have found that a minimum of
six ribs should be employed to obtain this important overlapping
feature, which feature is significant in the configuration of an
anchor point for a suture, as will be described hereinbelow.
[0061] Referring now to FIGS. 9-10, there may be seen a cross
section of a humeral head 10 identical to that described in
connection with previous FIGS. 1, 5 and 6. The bone anchor 80 has
been disposed within the drilled hole 18, with the proximal end
entirely below the surface of the cortical bone 12. A length of
suture 94 is shown threaded through the suture conduit 92 at the
proximal end 88 of the bone anchor 80. The length of suture 94 is
also shown threaded through the rotator cuff tendon 16 laying on
top of the humeral head 10. As shown particularly in FIG. 10, the
bone anchor 80 has been deployed by the application of a
compressive force to create the characteristic bending of the ribs
86 into their semi-circular state. The creation of this
semi-circular geometry in the ribs 86 increases the body diameter
of the bone anchor 80 such that the aggregate outside diameter of
the deformed ribs 86 is substantially larger than the nominal
diameter of the cylindrical body 82. In this manner, the anchor is
prevented from passing proximally out of the drilled hole 18 in the
hard cortical bone 12, as it is retained up against the inner
surface of the cortical bone 12. As discussed supra, the structure
is strengthened because of the overlapping expanded ribs 86. A knot
96, tied in the length of suture 94, secures the rotator cuff
tendon 16 to the humeral head 10.
[0062] It is to be understood that the figures of the bone and
anchors seen above are purely illustrative in nature, and are not
intended to perfectly reproduce the physiologic and anatomic nature
of the humeral head as expected to be seen in the human species,
nor to limit the application of the inventive embodiments to repair
of the rotator cuff. The invention is applicable to many different
types of procedures involving, in particular, the attachment of
connective or soft tissue to bone.
[0063] Accordingly, although an exemplary embodiment of the
invention has been shown and described, it is to be understood that
all the terms used herein are descriptive rather than limiting, and
that many changes, modifications, and substitutions may be made by
one having ordinary skill in the art without departing from the
spirit and scope of the invention.
* * * * *