Surgical suture abstract
A device and method for anchoring a surgical suture in solid tissue,
such as bone, which is implantable without prior drilling of a hole.
The device for anchoring a surgical suture to a solid tissue is
attachable to an external rotational drive and includes a self-drilling
body to which surgical suture is attachable, an assembly including
at least one flexible locking element, attached to or integrally
formed therewith, capable of assuming both an open and closed configurations.
The device is configured so that the assembly including at least
one flexible locking element in the closed configuration is releasably
engageable by the external rotational drive. The method for anchoring
a surgical suture to a solid tissue includes the step of causing
a self-drilling body to penetrate a soft tissue, the step of aligning
the self-drilling body with an anchor point on a bone, the step
of activating an external rotational drive, thereby causing the
self-drilling body to rotate and penetrate the anchor point in the
bone, and the step of actuating a mechanism for anchoring the self-drilling
body in the bone at the anchor point.
Surgical suture claims
What is claimed is:
1. A device for anchoring a surgical suture to a solid tissue,
the device being attachable to an external rotational drive, the
device comprising:
(a) a self-drilling body having a point of attachment for surgical
suture, said self-drilling body being configured for penetrating
both soft tissue and solid tissue, and said body defining an effective
drilling diameter;
(b) an assembly including at least one flexible locking element
said assembly capable of assuming both an open configuration wider
than said effective drilling diameter and a closed configuration
at least as narrow as said effective drilling diameter, said at
least one flexible locking element being attached to or integrally
formed with said self-drilling body; and
(c) the device being configured so that said assembly including
at least one flexible locking element in said closed configuration
is releasably engageable by the external rotational drive;
wherein said self drilling body is rotationally insertable into
a surface without prior drilling of a hole in said surface;
wherein said assembly including at least one flexible locking element
automatically assumes an open state substantially wider than said
effective drilling diameter when said external rotational drive
is detached after drilling, thereby anchoring said device in said
solid tissue.
2. The device of claim 1 further comprising:
(d) surgical suture attached to said point of attachment for surgical
suture.
3. The device of claim 1 wherein said point of attachment for
surgical suture rotates freely with respect to said self-drilling
body.
4. The device of claim 1 further comprising:
(e) a low friction coating on said self-drilling body, configured
so as to prevent damage to a soft tissue as said body penetrates
said soft tissue.
5. The device of claim 4 wherein said coating is selected from
the group of bio-resorbable polymers consisting of polyethers and
poly alpha-hydroxy acids.
6. The device of claim 4 wherein said coating is formed from a
bio-resorbable polymer consisting of a combination of polyethers
and poly alpha-hydroxy acids.
7. The device of claim 1 wherein said self-drilling body is composed
of a metal selected from the group of metals consisting of stainless
steel, titanium, gold, nickel and aluminum.
8. The device of claim 1 wherein said self-drilling body is composed
of an alloy of metals selected from the group of metals consisting
of stainless steel, titanium, gold, nickel and aluminum.
9. The device of claim 1 wherein said self-drilling body additionally
comprises a coating of diamond pieces.
10. The device of claim 1 wherein assembly including at least
one flexible locking element assumes an open state substantially
wider than said effective drilling diameter as a result of a mechanical
force applied to said device, thereby anchoring said device in said
solid tissue.
11. A method for anchoring a surgical suture to a solid tissue,
the method comprising the steps of:
(a) causing a self-drilling body to penetrate a soft tissue;
(b) aligning said self-drilling body with a desired anchor point
on a bone;
(c) activating an external rotational drive, thereby causing said
self-drilling body to rotate and penetrate said anchor point in
said bone; and
(d) actuating a mechanism for anchoring said self-drilling body
in said bone at said anchor point;
wherein said mechanism for anchoring is actuated by detachment
of said device from said external rotational drive.
12. The method of claim 11 wherein said self-drilling body comprises:
(i) a point of attachment for surgical suture;
(ii) a widest point which defines an effective drilling diameter;
(iii) an assembly including at least one flexible locking element,
said assembly capable of assuming both an open configuration wider
than said effective drilling diameter and a closed configuration
at least as narrow as said effective drilling diameter, said at
least one flexible locking element being attached to or integrally
formed with said self-drilling body; and
(iv) a configuration in which said assembly including at least
one flexible locking element in said closed configuration is releasably
engageable by the external rotational drive.
13. The method of claim 12 wherein said point of attachment for
surgical suture rotates freely with respect to said self-drilling
body.
14. The method of claim 11 further comprising the step of:
(f) coating said self-drilling body with a low friction coating,
said coating configured so as to prevent damage to said soft tissue
as said body penetrates said soft tissue.
15. The method of claim 14 wherein said coating is selected from
the group of bio-resorbable polymers consisting of polyethers and
poly alpha-hydroxy acids.
16. The method of claim 14 wherein said coating is formed from
a bio-resorbable polymer consisting of a combination of polyethers
and poly alpha-hydroxy acids.
17. The method of claim 11 wherein said self-drilling body is
composed of a metal selected from the group of metals consisting
of stainless steel, titanium, gold, nickel and aluminum.
18. The method of claim 11 wherein said self-drilling body is
composed of an alloy of metals selected from the group of metals
consisting of stainless steel, titanium, gold, nickel and aluminum.
19. The method of claim 11 wherein said self-drilling body additionally
comprises a coating of diamond pieces.
Surgical suture description
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to a surgical suture anchor for implantation
in solid tissue, such as bone, which is implantable without prior
drilling of a hole in the solid tissue. More particularly, the present
invention relates to a surgical anchor which can both pierce soft
tissue, such as muscle, and drill into bone. The surgical anchor
is self-setting within the solid tissue and serves as a point of
attachment for suture material which serves to attach a soft tissue
to the solid tissue containing the implanted anchor.
In orthopedic surgery there is often a need to attach a soft tissue,
including but not limited to muscle, to a solid tissue, including
but not limited to bone. A number of prior art devices, referred
to collectively as suture anchors, exist to perform this function.
Suture anchors for anchoring a suture to solid tissue, such as
bone, so that a soft tissue, such as muscle or ligament, may be
sutured to the bone are known in the art. Such suture anchors come
in a variety of shapes and designs which are reviewed in James E.
Carpenter et al., "Pull-Out Strength of Five Suture Anchors",
Arthroscopy, 9(1), pp. 109-113 (1993). These suture anchors may
be divided into several categories.
The first category is the harpoon-type or screw-type suture anchor,
which are drilled into cortical bone. This type is represented by,
for example, Cerrier et al. U.S. Pat. No: 5100417 and Hayhurst
et al. Canada PAT. NO: 2045903. This type of suture anchor is
held in place by a variety of methods including self-tapping, force
fitting, and inclusion of a resilient portion which flexes to frictionally
engage the bone material.
An additional category of suture anchor includes a rigid member
and a flexible, shape memory member. The flexible member lies flat
against the rigid member during insertion, and flexes away from
the rigid member once lodged inside the bone. This category includes,
for example, the prior art teachings of Gatturna et al. U.S. Pat.
Nos: 5046513 and 5192303.
A third category of suture anchor is substantially elongated and
is inserted with its longitudinal axis substantially parallel to
the bone hole through which it is inserted. The orientation of the
suture anchor is then adjusted upon reaching cancellous bone tissue
by pulling on the attached suture. This category of anchor is exemplified
by Hayhurst et al. U.S. Pat. No: 5041129 and Noblitt et al. U.S.
Pat. No: 5203787.
According to the teachings of Hayhurst, the suture anchor has a
substantially cylindrical rigid body with a central cavity and a
longitudinal slot extending from one end to approximately the middle
of the rigid body. A suture is positioned inside the central cavity,
and the anchor is inserted with the slot entering the bone last.
After properly positioning the anchor, the suture is pulled through
the slot towards its base, thereby reorienting the anchor with respect
to the bone, thereby fixing it in place.
According to the teachings of Noblitt, the suture anchor has an
offset portion to facilitate attachment of a suture. Once the anchor
has been placed in cancellous tissue, the suture is pulled in such
a way that it reorients the anchor so that its longitudinal axis
is substantially transverse to the bone hole through which it was
inserted.
A disadvantage common to all members of this third category of
anchors is that tension on the suture required for reorientation
of the anchor may put undue stress on the suture. In addition, the
introduction technique is complicated, requiring multiple insertion
tools.
All of the above-described suture anchors typically require complex
insertion tools, the use of which is time consuming and requires
considerable skill. Insertion of these prior art devices often requires
pre-drilling of the bone (U.S. Pat. Nos.: 4898156; 4899743;
4946468; 4968315; 5002550; 5501695; 5540718). Pre-drilling
is disadvantageous because it requires positioning of a soft tissue
relative to a solid tissue, selection of a site for drilling, release
of the soft tissue, drilling into the solid tissue, insertion of
the anchor, and repositioning of the soft tissue. This process is
time consuming and difficult. Repositioning of the soft tissue after
drilling may be inexact, leading to sub-optimal attachment. The
process lengthens the time of surgery increasing patient anxiety
and distress.
A fourth category of anchors includes screws which are either self-tapping
(for example U.S. Pat. No: 4632100) or require drilling of a pilot
hole. Screws often loosen with time, necessitating a second operation
to remove the loosened screw. In addition, when screws are set in
bone, the heads of the screws can protrude above the surface of
the bone in which they are set. These exposed screw heads present
an abrasive surface to surrounding soft tissue which may cause inflammation
or tissue damage. If a pilot hole must be drilled into the bone,
the installation procedure becomes lengthy, more so if the pilot
hole must be tapped to accept the screw. In addition, the nature
of a screw attachment tends to require that the pilot hole be located
on a relatively flat section of the bone, and toothed washers must
frequently be used in conjunction with the screws to fasten the
desired objects to the target bone. As a result of these constraints,
it may be necessary to locate the attachment point at a less than
optimal position.
A fifth category of anchors includes staples which are tapped or
hammered into the bone. Staples have their own set of disadvantages.
Bone staples must frequently be removed after they have been in
position for some time, necessitating a second operation. In addition,
staples must be positioned so as to maximize their holding power
in the bone and such positioning may conflict with the otherwise-optimal
position for attachment of objects to bone. The most serious drawback
of staples is that they may crack the bone during deployment, or
accidentally transect the object (e.g. soft tissue) being attached
to the bone, since it is difficult to control the extent of the
staple's penetration into the bone. Finally, once the staple has
been set into the bone, it is impossible to adjust the degree of
tension being applied to the object which is being attached to the
bone without setting a new staple.
In addition, prior art anchors which require drilling of holes
in the bone typically require holes with a diameter between 2.4
and 3.7 mm (radius (r) of 1.2 to 1.85 mm). Since weakening of the
bone is proportional to the area of the hole drilled, and since
the area (a) increases according to the formula a=.pi.(r.sup.2)
a small reduction in the diameter of the hole will greatly reduce
the area of the hole and therefore greatly reduce the degree to
which the structural integrity of the bone is compromised. For example,
a prior art device requiring a hole with a diameter of 2.4 mm has
an area of 4.52 mm.sup.2. Reducing the diameter of the hole to 1.8
mm, a 25% reduction, reduces the area to 2.54 mm.sup.2 a reduction
of 44%. Therefore, any invention which reduces the size of the hole
in the bone required to implant an anchor is inherently advantageous
because it facilitates retention of more of the structural integrity
of the bone.
The prior art teaches coating of materials to be implanted within
the body with bio-resorbable polymers such as poly (alpha-hydroxy-carboxylic
acid)/poly (oxyalkylene) to reduce inflammation and adhesions after
surgical implantation of a foreign body within a patient. (for example
U.S. Pat. Nos: 4826945 and 5711958). This material, or other
bio-resorbable polymers, may be used in conjunction with implantable
surgical anchors.
Citation or identification of any reference in this section or
in any other section of this application shall not be construed
as an admission that such reference is available as prior art to
the present invention.
There is thus a widely recognized need for, and it would be highly
advantageous to have, a surgical suture anchor which does not require
pre drilling of a hole, which is unthreaded, which can be installed
without benefit of special tools, which concurrently pierces soft
tissue and bone, and which makes a narrower diameter hole in the
bone than existing alternatives.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided
a device for anchoring a surgical suture to a solid tissue being
attachable to an external rotational drive, the device comprising:
(a) a self-drilling body having a point of attachment for surgical
suture, the self-drilling body capable of penetrating both soft
tissue and solid tissue, and the body having an effective drilling
diameter; (b) an assembly including at least one flexible locking
element, capable of assuming both an open configuration wider than
the effective drilling diameter and a closed configuration at least
as narrow as the effective drilling diameter, the at least one flexible
locking element being attached to or integrally formed with said
self-drilling body; and (c) an overall configuration in which the
assembly including at least one flexible locking element in said
closed configuration is releasably engageable by the external rotational
drive
According to another aspect of the present invention there is provided
a method for anchoring a surgical suture to a solid tissue, the
method comprising the steps of: (a) causing a self-drilling body
to penetrate a soft tissue; (b) aligning the self-drilling body
with a desired anchor point on a bone; (c) activating an external
rotational drive, thereby causing the self-drilling body to rotate
and penetrate the desired anchor point in the bone; and (d) actuating
a mechanism for anchoring the self-drilling body in the bone at
the anchor point.
According to further features in preferred embodiments of the invention
described below, surgical suture is attached to the point of attachment
for surgical suture prior to placement of the anchor in bone.
According to still further features in the described preferred
embodiments, the point of attachment for surgical suture rotates
freely with respect to the self-drilling body.
According to still further features in the described preferred
embodiments there is provided a low friction coating on said self-drilling
body, said coating configured to prevent damage to a soft tissue
as the body penetrates the soft tissue.
According to further features in preferred embodiments of the invention
described below, the low friction coating is selected from the group
of bio-resorbable polymers consisting of polyethers, poly alpha-hydroxy
acids, and combinations thereof.
According to still further features in the described preferred
embodiments the self-drilling body is composed of a metal selected
from the group of metals consisting of stainless steel, gold, titanium,
nickel, aluminum and alloys thereof.
According to further features in preferred embodiments of the invention
described below, the assembly including at least one flexible locking
element automatically assumes an open configuration substantially
wider than the effective drilling diameter when the external rotational
drive is detached after drilling, thereby anchoring the device in
the bone.
According to still further features in additional preferred embodiments,
the assembly including at least one flexible locking element assumes
an open configuration substantially wider than the effective drilling
diameter as a result of a mechanical force applied to the device,
thereby anchoring the device in said bone.
According to yet another aspect of the present invention there
is provided a method for preserving the inherent integrity of a
bone during implantation of a surgical suture anchor, the method
comprising the step of creating a hole in the bone, the hole having
a diameter of less than about 2.0 mm.
According to further features in preferred embodiments of the invention
described below, the diameter of the hole is no more than about
1.6 mm.
According to still further features in the described preferred
embodiments, the diameter of the hole is no more than about 1.4
mm.
According to still further features in the described preferred
embodiments, the diameter of the hole is no more than about 1.0
mm.
The present invention successfully addresses the shortcomings of
the presently known configurations by providing a device and method
for anchoring a surgical suture in bone without pre-drilling a hole,
without use of complicated installation tools, and without unduly
compromising the integrity of the bone.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is herein described, by way of example only, with
reference to the accompanying drawings, wherein:
FIG. 1 is a side view a preferred embodiment of the device of the
present invention showing the tendency of the device to revert from
a closed configuration to an open configuration in which the width
of the device is greater than the effective drilling diameter.
FIG. 2 is a diagram of the device anchored within a hole bored
in bone.
FIG. 3 is a diagram of a second preferred embodiment of the device
featuring a rotating suture point of attachment.
FIG. 4 is a diagram of the preferred embodiment of FIG. 3 featuring
a rotating suture point of attachment with the suture point of attachment
removed.
FIG. 5 is a diagram of the rotating suture point of attachment
for use with the device of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is of a device and method for anchoring a
surgical suture to a solid tissue, including but not limited to,
bone. The present invention does not require pre-drilling a hole,
use of complicated installation tools, or undue compromise of the
integrity of the bone. Specifically, the present invention can be
used to accurately align a soft tissue with a desired anchor point
and attach the soft tissue to the desired anchor point.
The principles and operation of a device and method for anchoring
a surgical suture to a solid tissue according to the present invention
may be better understood with reference to the drawings and accompanying
descriptions.
Before explaining at least one embodiment of the invention in detail,
it is to be understood that the invention is not limited in its
application to the details of construction and the arrangement of
the components set forth in the following description or illustrated
in the drawings. The invention is capable of other embodiments or
of being practiced or carried out in various ways. Also, it is to
be understood that the phraseology and terminology employed herein
is for the purpose of description and should not be regarded as
limiting.
For purposes of this specification and the accompanying claims,
the term "self-drilling body" refers to any body which
is rotationally insertable into a surface without prior drilling
of a hole in that surface.
For purposes of this specification and the accompanying claims,
the term "point of attachment for surgical suture" refers
to a portion of the self-drilling body which is designed to hold
the suture material securely to the self-drilling body under the
conditions of use described herein.
For purposes of this specification and the accompanying claims,
the term "anchor point" refers to a location in a solid
tissue chosen by the person deploying the device of the present
invention, the anchor point being the position at which the self-drilling
body will be inserted into the solid tissue.
For purposes of this specification and the accompanying claims,
the term "widest point", as used with respect to the self-drilling
body, refers to the point at which the body has the greatest diameter
in a plane perpendicular to a vertical axis of the body.
Referring now to the drawings, FIG. 1 illustrates the device of
the present invention in open 2 and closed 3 configurations. The
device comprises: (a) self-drilling body 4 having a point of attachment
for surgical suture 10 self-drilling body 4 being capable of penetrating
both soft tissue and bone, and having an effective drilling diameter
14 represented in the drawing by a double headed arrow; (b) an assembly
including at least one flexible locking element 16 (two are pictured),
capable of assuming both an open configuration 3 wider than effective
drilling diameter 14 and a closed configuration 2 at least as narrow
as effective drilling diameter 14 wherein flexible locking elements
16 are attached to or integrally formed with self-drilling body
4; and (c) an overall configuration in which the assembly including
at least one flexible locking element 16 in closed configuration
2 is releasably engageable by the external rotational drive(not
pictured).
Upon disassembly from the external rotational drive, the device
is transformed from closed configuration 2 to open configuration
3 via outward movement of flexible locking elements 16 as indicated
by arrows 20. This transformation is automatic in the pictured preferred
embodiment of the present invention because of an inherent spring-like
memory in locking elements 16. Alternate preferred embodiments accomplish
this transformation automatically via other means, including but
not limited to the use of springs which are not integral parts of
locking mechanism 16. Additional preferred embodiments feature a
transformation from closed configuration 2 to open configuration
3 which is the result of a mechanical force applied to device 2
by, for example, pulling on suture 12.
According to preferred embodiments of the present invention, self-drilling
body 4 may be constructed of materials including, but not limited
to, at least one metal selected from the group of metals consisting
of stainless steel, titanium, gold, nickel, aluminum and alloys
thereof either with or without the addition of diamond pieces as
a coating. According to some preferred embodiments of the present
invention a low friction coating of a bio-resorbable polymer consisting
of polyethers, poly alpha-hydroxy acids, or combinations thereof
is added to prevent damage to soft tissue as the self-drilling body
passes therethrough.
According to preferred embodiments of the present invention, suture
12 is attached to suture point of attachment 10 prior to implantation
of self-drilling body 4 in a bone of a patient. However, the present
invention also encompasses embodiments in which suture 12 is attached
to suture point of attachment 10 after implantation of self-drilling
body 4.
According to some preferred embodiments (FIGS. 3 4 and 5), point
of attachment for surgical suture 10 is situated in receptacle 28
where it rotates freely with respect to self-drilling body 4 while
connected to suture material 12 by means of hole 30. According to
some preferred embodiments, tension on suture material 12 attached
to hole 30 causes flexible locking elements 16 to change from closed
configuration 2 to open configuration 3.
In order to use the device of the present invention, it must first
be attached to an external rotational drive, forcing it to assume
closed configuration 2. This rotational drive is selected from commercially
available rotational drives. As a result, flexible locking element
16 may assume any one of a number of configurations in order to
be engageable by the chosen external rotational drive. The present
invention is intended to encompass all configurations of locking
elements 16 which fit existing rotational drives, as well as all
configurations of locking elements 16 which may be required to be
engageable by rotational drives which become available in the future.
In order to use the device of the present invention, self-drilling
body 4 is forced through a soft tissue during use. In embodiments
where self-drilling body 4 is rotating during this process, a low
friction coating may be present upon self-drilling body 4 to prevent
soft tissue damage during this step. The low friction coating is
subsequently self removing as the self-drilling body begins to enter
the bone. Such a coating might be composed of, for example, polyethers,
poly alpha-hydroxy acids, or combinations thereof, such as Repel.TM.
(Life Medical Sciences, Edison, N.J.).
Self-drilling body 4 is then aligned with a desired anchor point
on a bone. The external rotational drive is activated, thereby causing
self-drilling body 4 to rotate and create a circular hole 24 (FIG.
2) at the desired anchor point. As self-drilling body 4 penetrates
the bone, a cylindrical cavity 26 is created. This cavity will conform
at its deepest point to the shape of the leading edge of self-drilling
body 4 forming, for example, a cone (FIG. 2) as defined by shaded
area 25. After self-drilling body 4 has penetrated the bone to the
desired depth, the external rotational drive is detached. According
to preferred embodiments, this detachment automatically actuates
a mechanism for anchoring self-drilling body 4 in the newly created
cylindrical cavity 26 by means of locking mechanism 16 which assume
open configuration 3 in which the distance between ends 19 of locking
mechanism 16 is greater than effective drilling diameter 14. According
to alternate embodiments, actuation of this anchoring mechanism
requires a mechanical input, including but not limited to, application
of tension to suture 12.
According to preferred embodiments of the present invention, effective
drilling diameter 14 is less than about 2 mm, more preferably less
than about 1.6 mm, more preferably less than about 1.4 m, most preferably
less than about 1.0 mm. This feature serves to preserve bone integrity,
allowing installation of numerous anchors in close proximity to
one another without undue risk to the patient.
Although the invention has been described in conjunction with specific
embodiments thereof, it is evident that many alternatives, modifications
and variations will be apparent to those skilled in the art. Accordingly,
it is intended to embrace all such alternatives, modifications and
variations that fall within the spirit and broad scope of the appended
claims.
All publications cited herein are incorporated by reference in
their entirety. |