System for anchoring tissue to bone

A system for anchoring tissue to bone includes an anchor member having an outer, bone engaging wall, a distal end, and a proximal end, a suture receiving slot extending partially into the anchor member, forming an internal passageway ending in a suture seat. The suture seat is integral with the anchor member and is formed within the anchor member.

CROSS-REFERENCE TO RELATED APPLICATIONS 
Not Applicable. 
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
Not Applicable. 
FIELD OF THE INVENTION 
The invention relates to a system for anchoring tissue to bone, and more 
particularly to a system for anchoring soft tissue to bone. 
BACKGROUND OF THE INVENTION 
Systems and devices for anchoring sutures to bone are commonly used in 
medical or surgical operations. Anchored sutures are typically used to 
attach soft tissue, such as ligaments, tendons and muscles, to bone or 
inanimate objects, such as prostheses, to bone. The attachment may hold 
the tissue to a bone for an extended period of time to allow healing to 
occur. Alternatively, the attachment may be used to hold tissue in place 
temporarily during a surgical procedure to help perform or optimize that 
procedure. 
Conventional suture anchors may be inserted into a preformed bore in the 
bone, driven directly into the bone or driven into the bone in the manner 
of a common screw, the screw-type anchor being inserted with or without a 
preformed bore in the bone. U.S. Pat. No. 4,898,156 provides an example of 
the insertion-type suture anchor. In this example, a suture is attached to 
the anchor by capturing a knotted end of the suture in the anchor's 
distally located blind hole, while the free end of the suture exits the 
anchor by a side slot or an axial through-hole in the anchor body. 
An example of the screw-type suture anchor is provided in U.S. Pat. No. 
5,156,616. A suture is attached to this anchor by capturing a knotted end 
of the suture thread in a distal portion of an axial passageway, with the 
free end of the suture extending proximally through the axial passageway. 
Conventional suture anchors for attaching soft tissue to bone often require 
that a knot be tied in the suture thread in order to attach the suture to 
the anchor. Such knot tying procedures can be quite difficult and time 
consuming, especially in closed (e.g. arthroscopic) surgical procedures. 
It is sometimes desirable to avoid knots and other bulky attachment means 
because such attachments can irritate tissue in the area in which they are 
located, and can become loose over time. 
Some conventional suture anchors suffer from additional disadvantages as 
well. Many conventional suture anchors have sharp edges or provide small 
passageways through which the suture must be threaded, causing 
difficulties or delays in threading the suture. In some instances, 
off-axis suture seating or off-axis exit features found on conventional 
anchors may result in disadvantageous movement or twisting of the anchor 
after insertion in the bone. Attachment of the suture thread to a distal 
portion of the anchor may lead to the same disadvantageous movement or 
twisting. 
Moreover, where two free ends of suture thread are required or desired, 
unwanted tangling and knotting may occur when two suture ends exit the 
anchor through a single hole in the anchor body or on the same side of the 
anchor body. 
One disadvantage to using screw-type anchor devices is that suture thread 
can be abraded or otherwise damaged when the anchor is threaded into bone 
as the suture is disposed between the bone and threads of the anchor. It 
is thus necessary to drill a hole of larger than desired diameter in the 
bone in order to prevent any such damage to the suture when the suture 
anchor is deployed. 
SUMMARY OF THE INVENTION 
The present invention provides a system for anchoring tissue to bone 
including an anchor member having a suture receiving slot. 
In one embodiment, the suture receiving slot is formed in a sidewall of the 
anchor member. The slot extends from an opening in the sidewall to an 
internal suture seat, creating a passageway by which an intermediate 
portion of suture thread may be threaded. The anchor member can also 
include one or more suture retaining structures which serve to retain a 
captured portion of suture thread within the suture receiving slot. 
In another embodiment, the anchor member is substantially cylindrical and 
includes external threads located on its outer surface. The suture 
receiving slot is formed in the distal end of the anchor member and 
extends proximally to an internal retaining wall. The anchor member also 
includes one or more breaks in the external threads. The breaks are 
aligned with the suture receiving slot and may be used to seat a portion 
of the suture thread extending proximally from the internal retaining 
wall.

DETAILED DESCRIPTION OF THE INVENTION 
A system 10 for anchoring tissue to bone is illustrated in FIG. 1. This 
exemplary system includes an anchor member 12, an installation tool 14, 
and a suture thread 16. 
Referring now to FIG. 2, an anchor member 12 in accordance with the 
invention is illustrated. The anchor member 12 has a distal end 18, a 
proximal end 20, a sidewall 22 disposed between the distal and proximal 
ends, and a suture receiving slot 24. The suture receiving slot 24 extends 
from an opening formed in the side wall 22 of the anchor member 12 to a 
suture seat 26 within the anchor member 12. The suture receiving slot 24 
forms an internal passageway 28 and includes one or more suture retaining 
structures 30. The slotted anchor member may be made using any 
biomedically compatible material. Titanium alloys are preferred, but 
absorbable and non-absorbable polymers may also be employed. 
In the embodiment of FIG. 2, the anchor member 12 is substantially 
cylindrical in shape and the distal end 18 forms an apex. The exemplary 
anchor member 12 additionally comprises two opposed deformable barbs 32, 
34 extending from the side wall 22 of the anchor member 12. As further 
shown in FIG. 2, the free ends of the deformable barbs 32, 34 may extend 
outward from the anchor member 12 and proximally (toward the proximal end 
20 of the anchor member 12) such that each barb defines an angle that is 
between about 100 and 900 with respect to a longitudinal axis 36 of the 
anchor member 12. More or fewer deformable barbs may be provided as 
desired to ensure proper retention of the anchor member 10 within a bone. 
In an alternative embodiment, the anchor member may include external 
threads as a structural element by which the anchor member is secured 
within a bone. 
In the exemplary anchor member 12, the suture receiving slot 24 is 
curvilinear. The suture receiving slot 24 extends from an opening in the 
sidewall 22 of the substantially cylindrical anchor member 12, and forms a 
passageway 28 which extends inward to the longitudinal axis 36 of the 
anchor member 12 as it curves toward the proximal end 20 of the anchor 
member 12. Accordingly, one interior end of the passageway 28 forms a 
suture seat 26 which is transverse to the longitudinal axis 36 of the 
anchor member 12, and opposed to the proximal end 20 of the anchor member 
12. If the anchor member 12 is solid, the suture seat 26 will be a wall 
interior to, and integral with, the anchor member 12 which marks an end of 
the passageway 28. If the anchor member 12 is not solid, the suture seat 
26 may be formed by the surfaces integral with the sidewall 22 of the 
anchor member 12 which mark an end of the passageway 28. 
The suture seat 26, as shown in FIG. 2, is coaxial with the longitudinal 
axis 36. This configuration, wherein the suture seat 26 and the suture 
retaining structures 30 are adapted to retain a suture thread so that the 
thread is coaxial with the longitudinal axis 36, may be referred to as 
"on-axis" suture retention. As required, off-axis suture retention 
configurations, wherein the retained suture is not coaxial with the 
longitudinal axis 36, may also be employed. 
The exemplary suture seat 26 is located toward the proximal end 20 of the 
anchor member 12. Preferably, suture seat 26 is disposed proximally to the 
deformable barbs 32, 34. While proximal suture seating may be 
advantageous, other locations may be used as required. 
The suture seat 26 and suture retaining structures 30 may be provided with 
rounded edges. Rounding the edges will reduce the likelihood of damaging a 
suture thread during threading or use of the system. The anchor member 12 
may also be provided with grooves 38, extending from the suture seat 26 to 
the proximal end 20 of the anchor member, capable of seating a length of 
suture thread. 
The anchor member 12 is further provided with one or more suture retaining 
structures 30. The term "suture retaining structure," as used herein, 
refers to any structural element which serves to retain a suture in the 
suture seat 26 or which reduces the probability that a retained suture 
will escape from the suture receiving slot 24 when the retained suture is 
slack. 
Where the passageway 28 is non-linear, the suture retaining structure may 
comprise an obstruction formed in the sidewall 22 of the anchor member 12 
by a change in direction of the passageway 28. In the exemplary embodiment 
shown in FIG. 2, the suture retaining structure 30 is formed in the 
sidewall 22 of the anchor member 12 by the curvilinear shape of the 
passageway 28. 
Additional embodiments in which suture receiving slots 24 form 
multidirectional passageways are shown in FIGS. 3-5. In each of these 
embodiments, changes in the direction of the passageways 28 create 
obstructions which serve as suture retaining structures 30a-g. 
In FIGS. 3-4, the suture receiving slots 24 each define linear passageway 
segments 28a-d which communicate at right angles. Each of these slots has 
a first linear passageway segment 28a, 28c which is parallel to the 
longitudinal axis 36 of the anchor member 12, and a second linear 
passageway segment 28b, 28d which is perpendicular to and communicates 
with the first linear passageway segment. The suture receiving slot 24 
illustrated in FIG. 5 is similar to that of FIG. 4, but additional suture 
retaining structures 30e, 30f are provided in the transverse passageway 
segment 28e. In FIG. 6, a suture receiving slot 24 which defines a linear 
passageway 28 is illustrated. 
Referring again to FIG. 1, the tissue-to-bone anchoring system of the 
invention may also comprise a suture thread 16, having an intermediate 
portion and two free ends 40, 42, engaged within the suture receiving slot 
24 such that the intermediate portion of the suture thread 16 is retained 
within the suture receiving slot 24 by the suture retaining structures 30 
and the suture seat 26. The two free ends 40, 42 of the suture thread 16, 
that is, the portions of the suture thread 16 which are not engaged within 
the suture receiving slot, may then extend toward the proximal end 20 of 
the anchor member 12 from opposing sides of the suture receiving slot 24. 
Additionally, a portion of the suture thread 16 may be seated in grooves 
38 formed in the anchor member 12. 
The system for anchoring soft tissue to bone of the present invention may 
also comprise an anchor member insertion tool 14 having a handle end (not 
shown) and a distal end 44 as shown in FIG. 1. The distal end 44 of the 
tool 14 may be matable with the proximal end 20 of the anchor member 12. 
The anchor member 12 may then be removably pre-mated to the distal end 44 
of the insertion tool 14. 
FIGS. 7 to 9 are illustrative of an alternative embodiment of an anchor 
member 110 useful with the system of the invention. A substantially 
cylindrical anchor member 110 is provided. The anchor member has an outer, 
or bone engaging, wall 112 with external threads 114 formed on at least a 
portion of the outer wall. The anchor member 110 also has a proximal end 
116 and a distal end 118, the distal end forming an apex. 
A suture receiving slot 120 is formed in the distal end 118 of the anchor 
member 110. The suture receiving slot 120 extends from an opening at the 
distal end 118 of the anchor member to an internal retaining wall 122 
within the anchor member 110. The slot 120 separates at least a portion of 
the distal end of the anchor member into two adjacent segments 124, 126. 
The anchor member 110 is further provided with at least one break 128 
formed in the external threads 114 of the anchor member. The exemplary 
anchor member 110 is provided with twin opposed breaks 128, 130 in the 
external threads 114. The breaks 128, 130, as best illustrated in FIG. 8, 
are preferably made in each thread over the length of the anchor member 
and they are effective to seat a length of suture thread within the 
threads. That is, the breaks 128, 130, which are preferably aligned with 
the suture receiving slot 120, extend from the suture receiving slot 120 
to the proximal end 116 of the anchor member 110. An elongate slot or 
groove (as shown in FIGS. 7 and 8, grooves accompany each of the breaks 
128, 130 in the threads) may also be formed in the outer wall 112 
coincident with the breaks in the threads, allowing the suture thread to 
be seated more deeply within the threads. 
The suture receiving slot, as well as the twin opposed breaks in the 
external threads of the anchor member, may be coaxial with a longitudinal 
axis 132 of the anchor member 110. Accordingly, the slotted anchor member 
may be adapted so that the retained suture is centered on the longitudinal 
axis 132 of the anchor member ("on-axis" suture retention). As with the 
embodiment of the anchor member shown in FIGS. 1-6, off-axis suture 
retention may be employed as required. 
The suture receiving slot 120 may also be adapted to seat a portion of 
suture thread in proximity to the proximal end 116 of the anchor member 
110. In one embodiment this can be accomplished by extending the slot over 
at least one-half of the length of the anchor member. 
Anchor member 110 may be part of a system for anchoring tissue to bone. 
This system may also comprise a length of suture thread (not shown) 
disposed in the suture receiving slot 120 such that an intermediate 
portion of the thread is retained within the anchor member 110 by the 
internal retaining wall 122. The two free ends of the suture thread may 
then extend proximally across the length of the anchor member and be 
disposed within the breaks 128 in the external threads 114 formed on 
opposite sides of the anchor member 110. 
The width of the suture receiving slot 120 must be sufficient to receive 
and retain the suture thread and will depend upon the overall dimensions 
of the anchor member. The width of the suture receiving slot 120 is not 
otherwise particularly limited, but by way of example, can be in the range 
of about 0.010 to 0.036 inches. Similarly, the breaks 128, 130 in the 
external threads 114 must be of sufficient width and depth to retain the 
suture thread within the length of the breaks. The width of the breaks 
128, 130 in the external threads 114 is not otherwise particularly 
limited, but by way of example, can be in the range of about 0.010 to 
0.036 inches. The breaks in the threads can be of virtually any depth as 
long as they are not so deep as to compromise the structural integrity of 
the anchor member. Preferably, the width of the remaining anchor material 
(between the opposed breaks) should be in the range of about 0.020 to 
0.048 inches. 
The slotted anchor member 110 of the invention may be adapted, by 
appropriate configuration of the external threads 114 and the breaks 128, 
130 therein, to seat within a bore formed in a bone wherein the bore has a 
diameter that is substantially equal to or slightly less than the diameter 
of the anchor member 110. 
The system for anchoring soft tissue to bone using anchor member 110 may 
also comprise an anchor member installation tool 14 having a distal end 44 
which is adapted to mate with the proximal end 116 of the anchor member 
110. In one embodiment, as shown in FIG. 8, the external threads 114 
closest to the proximal end 116 of the exemplary anchor member 110 can be 
adapted to form a hexagonal region 134 which extends from a predetermined 
point along the longitudinal axis 132 to the proximal end 116 of the 
anchor member 110. The hexagonal region 134 may be used to engage or mate 
with an installation tool 14. In some embodiments, the anchor member 112 
may be removably pre-mated to the distal end 44 of the insertion tool 14. 
It will be understood that the foregoing is only illustrative of the 
principles of the invention, and that various modifications can be made by 
those skilled in the art without departing form the scope and spirit of 
the invention. All references cited herein are expressly incorporated by 
reference in their entirety.