U.S. patent application number 10/405028 was filed with the patent office on 2004-04-01 for threaded bone tunnel dilator.
Invention is credited to Fallin, T. Wade, Hays, Greta Jo, Hicken, Greg.
Application Number | 20040064143 10/405028 |
Document ID | / |
Family ID | 23716330 |
Filed Date | 2004-04-01 |
United States Patent
Application |
20040064143 |
Kind Code |
A1 |
Hicken, Greg ; et
al. |
April 1, 2004 |
Threaded bone tunnel dilator
Abstract
A cannulated threaded bone tunnel dilator that accurately
advances through bone and dilates a bone tunnel in a gentle,
controlled manner, including a distal tapered, threaded tip and a
body mounted on the distal end of a shaft. The proximal end of the
shaft includes a drive attachment for rotating the dilator so as to
threadingly advance the dilator. In use, a guidewire is driven into
bone, and then the surgeon advances the dilator along the guidewire
until the tip of the dilator engages the bone. The surgeon then
rotates the dilator clockwise so as to threadingly advance the
dilator through the bone until the dilator reaches a desired depth.
After reaching the desired depth, the surgeon removes the dilator
by rotating the dilator counterclockwise and retracting the dilator
from the then-compacted bone tunnel. The peaks and troughs of the
dilator's thread compact the bone so as to create the dilated bone
tunnel. However, the peaks and troughs do not extend beyond a
smooth cylindrical body, thus, following dilation, the resultant
bone tunnel is smooth and compacted.
Inventors: |
Hicken, Greg; (Logan,
UT) ; Hays, Greta Jo; (Logan, UT) ; Fallin, T.
Wade; (Hyde Park, UT) |
Correspondence
Address: |
Mark J. Pandiscio
Pandiscio & Pandiscio
470 Totten Pond Road
Waltham
MA
02154
US
|
Family ID: |
23716330 |
Appl. No.: |
10/405028 |
Filed: |
April 1, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10405028 |
Apr 1, 2003 |
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09432477 |
Nov 1, 1999 |
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6540752 |
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Current U.S.
Class: |
606/90 |
Current CPC
Class: |
A61B 17/1604 20130101;
A61B 17/1615 20130101; A61B 17/885 20130101 |
Class at
Publication: |
606/090 |
International
Class: |
A61B 017/58 |
Claims
What is claimed is:
1. A dilator comprising: a tip having an axis and a thread disposed
about said axis, said thread being defined by a peak and an
adjacent trough; wherein said peak and said trough are adapted to
substantially displace bone.
2. A dilator according to claim 1 wherein said tip defines a
proximally-expanding taper.
3. A dilator according to claim 2 wherein said thread corresponds
to said taper.
4. A dilator according to claim 2 wherein said taper is selected
from the group consisting of straight, compound, parabolic,
elliptical and diverse arc segment tapers.
5. A dilator according to claim 2 wherein said taper defines an
angle of between about 5 and about 30 degrees with respect to said
axis.
6. A dilator according to claim 2 wherein said taper defines an
angle of about 10.85 degrees with respect to said axis.
7. A dilator according to claim 1 wherein said thread defines a
pitch of between about 0.060 and about 0.120 inches.
8. A dilator according to claim 1 wherein said dilator further
comprises a body having a surface with an axial projection, said
body being mounted on said tip.
9. A dilator according to claim 8 wherein said body is
cylindrical.
10. A dilator according to claim 8 wherein said body includes a
proximally-expanding linear taper.
11. A dilator according to claim 8 wherein said body includes a
proximally-expanding arcuate flare.
12. A dilator according to claim 8 wherein said body includes means
for imparting texture on a bone tunnel wall.
13. A dilator according to claim 12 wherein said texture is
smooth.
14. A dilator according to claim 8 wherein said thread continues
proximally about said body, said peak being truncated at or within
said axial projection.
15. A dilator according to claim 14 wherein said tip defines a
proximally-expanding taper with a tapered projection; and said
thread corresponds to said tapered projection.
16. A dilator according to claim 1 wherein said trough proximally
and radially expands until said trough is co-extensive with said
peak.
17. A dilator according to claim 1 wherein said tip has a central
opening configured to receive a guidewire.
18. A dilator according to claim 1 wherein said dilator further
comprises a shaft, defining a shaft perimeter, mounted on said tip;
wherein said tip defines a tip perimeter; and wherein said shaft
perimeter is radially inferior to said tip perimeter.
19. A method for dilating bone comprising: threadingly advancing
through a bone a dilator having a thread with a peak and a trough;
wherein said peak and said trough are adapted to substantially
displace bone.
20. A method according to claim 19 wherein said trough displaces
bone a substantially similar amount as said peak.
21. A method according to claim 19 wherein said method further
comprises: driving a guidewire through a bone prior to said
advancing; and placing said dilator on said guidewire prior to said
advancing; wherein said advancing occurs along said guidewire.
22. A method according to claim 19 wherein said dilator has a body
with a surface radially superior to said thread, whereby said
advancing imparts a texture on a bone tunnel corresponding to said
surface.
23. A method according to claim 19 wherein said texture is
smooth.
24. A method according to claim 19 wherein said method further
comprises creating a pilot hole in the bone prior to said
advancing.
25. A method according to claim 19 wherein said dilator includes a
tip, said thread being disposed on said tip, and wherein said tip
defines a proximally-expanding taper.
26. A method according to claim 25 wherein said thread corresponds
to said taper.
27. A method according to claim 25 wherein said taper is selected
from the group consisting of straight, compound, parabolic,
elliptical and diverse arc segment tapers.
28. A method according to claim 25 wherein said taper defines an
angle of between about 5 and about 30 degrees with respect to the
longitudinal axis of said tip.
29. A method according to claim 25 wherein said taper defines an
angle of about 10.85 degrees with respect to the longitudinal axis
of said tip.
30. A method according to claim 25 wherein said dilator includes a
body having a surface with an axial projection, said body being
mounted on said tip.
31. A method according to claim 30 wherein said body is
cylindrical.
32. A method according to claim 30 wherein said body includes a
proximally-expanding linear taper.
33. A method according to claim 30 wherein said body includes a
proximally-expanding arced flare.
34. A method according to claim 30 wherein said body includes means
for imparting texture on a bone tunnel wall.
35. A method according to claim 34 wherein said texture is
smooth.
36. A method according to claim 30 wherein said thread continues
proximally about said body, the peak being truncated at or within
the axial projection.
37. A method according to claim 25 wherein said tip defines a
proximally-expanding taper with a tapered projection; and said
thread corresponds to said tapered projection.
38. A method according to claim 25 wherein said tip has a central
opening configured to receive a guidewire.
39. A method according to claim 19 wherein said thread defines a
pitch of between about 0.060 and 0.120 inches.
40. A method according to claim 19 wherein said trough proximally
and radially expands until said trough is co-extensive with said
peak.
41. A dilator system comprising: a dilator comprising a tip having
an axis and a thread disposed about said axis, said thread being
defined by a peak and an adjacent trough, wherein said peak and
said trough are adapted to substantially displace bone; and a
guidewire received in said dilator.
42. A system according to claim 41 wherein said dilator is adapted
to be driven by a driver.
43. A system according to claim 42 wherein said system further
includes a driver operatively connected to said dilator.
44. A method for attaching a member to a bone comprising forming a
bone tunnel by dilating with a threaded device.
45. A dilator comprising: a tip having an axis and a thread
disposed about said axis, said thread being defined by a peak and
an adjacent trough; wherein said peak and said trough are adapted
to substantially displace bone; wherein said trough proximally and
radially expands until said trough is co-extensive with said
peak.
46. A dilator comprising: a tip having an axis and a thread
disposed about said axis, said thread being defined by a peak and
an adjacent trough; and a body having a surface with an axial
projection, said body being mounted on said tip; wherein said peak
and said trough are adapted to substantially displace bone; and
wherein said thread continues proximally about said body, said peak
being truncated at or within said axial projection.
47. A dilator comprising: a tip having an axis and a thread
disposed about said axis, said thread being defined by a peak and
an adjacent trough; and a shaft, defining a shaft perimeter,
mounted on said tip; wherein said peak and said trough are adapted
to substantially displace bone; wherein said tip defines a tip
perimeter; and wherein said shaft perimeter is radially inferior to
said tip perimeter.
48. A method for dilating bone comprising: driving a guidewire into
the bone; placing a dilator, having a thread with a peak and a
trough, on said guidewire; and threadingly advancing said dilator
through said bone; wherein said advancing occurs along said
guidewire; and wherein said peak and said trough are adapted to
substantially displace bone.
49. A method for dilating bone comprising: creating a pilot hole in
the bone; and threadingly advancing through said pilot hole a
dilator having a thread with a peak and a trough; wherein said peak
and said trough are adapted to substantially displace bone.
50. A dilator comprising: a tip having an axis and a thread
disposed about said axis, said thread having a proximal end and a
distal end; wherein said thread is further defined by a smaller
outside diameter at its distal end and a larger outside diameter at
its proximal end; and wherein said thread is adapted over its
entire length to gradually displace bone and form a bone
tunnel.
51. A dilator comprising: a tip having an axis and a thread
disposed about said axis, said thread being defined by a peak and
an adjacent trough; wherein said peak and said trough are adapted
to gradually displace bone, said trough displacing bone a
substantially similar amount as said peak, so as to relatively
gently form a bone tunnel.
52. A dilator comprising: a tip having a proximal end, a distal end
and an axis extending between said proximal end and said distal
end, and a thread disposed about said axis, said thread being
defined by a peak and an adjacent trough; wherein said peak and
said trough are adapted to substantially displace bone; and further
wherein said thread extends to said distal end of said tip.
53. A dilator comprising: a tip having an axis and a thread
disposed about said axis, said thread being defined by a peak and
an adjacent trough; wherein said peak and said trough are adapted
to substantially displace bone; wherein said tip defines a
proximally-expanding taper with a tapered projection, said thread
corresponds to said tapered projection, and the taper at said
trough extends along the entire length of said thread.
54. A dilator according to claim 1 wherein said dilator is
configured so that said peak and trough displace bone more than 2
mm.
55. A dilator comprising: a body, configured to dilate a bone
tunnel, having a flute; wherein said flute is configured to cut
bone only when said dilator is rotated in a first direction.
56. The dilator of claim 55, wherein said flute is located on a
proximal end of said body.
57. The dilator of claim 55, wherein said flute is located on a
distal end of said body.
58. The dilator of claim 55, said body having a second flute;
wherein said second flute is configured to cut bone only when said
dilator is rotated in a second direction.
59. The dilator of claim 58, wherein said second flute is located
on a proximal end of said body.
60. The dilator of claim 58, wherein said second flute is located
on a distal end of said body.
61. The dilator of claim 58, wherein said second flute is located
on an end of said body opposite to said flute.
Description
FIELD OF THE INVENTION
[0001] This invention relates to attaching tissue and non-tissue
members to bone. More specifically, this invention relates to
dilating a bone tunnel so as to improve member attachment to a
bone.
BACKGROUND OF THE INVENTION
[0002] Many medical procedures involve attaching tissue or an
artificial member to, or inside of, a bone. For example, repairing
a detached ligament frequently involves re-attaching the detached
ligament to the bone. Often, the repair involves removing the
damaged tissue and replacing it with a graft or artificial
substitute.
[0003] Many techniques exist for attaching a natural or artificial
member to a bone. Sometimes the member is drawn to, and/or secured
in, a bone tunnel in the bone. For example, referring to FIG. 1, to
repair a damaged knee ligament, such as an anterior cruciate
ligament (ACL) or a posterior cruciate ligament (PCL), the damaged
ligament is often replaced with a graft ligament. Replacing the
damaged ligament with a graft ligament involves attaching the graft
ligament to the patient's femur and tibia. This is typically done
by forming a bone tunnel B.sub.1 in the tibia T, and a coincidental
bone tunnel B.sub.2 in the femur F. A graft ligament L is then
threaded into the bone tunnels B.sub.1 and B.sub.2. One end of the
graft ligament L is attached to the tibia T, and the other end of
the graft ligament L is attached to the femur F.
[0004] In some cases, the distal end of the graft ligament L is
secured to the femur F with an interference screw (not shown) which
wedges the graft ligament laterally against the side wall of the
bone tunnel B.sub.2. The interference screw simultaneously engages
both the side wall of the bone tunnel and a portion of the graft
ligament L, thereby fixing the graft ligament to the bone with an
interference coupling. It will be appreciated that with such an
arrangement, secure attachment of the graft ligament L in the bone
tunnel depends on the quality and integrity of the side wall of the
bone tunnel, as well as the effectiveness of the attachment
mechanism which is used to attach the graft ligament to the
bone.
[0005] Sometimes a member (both tissue and non-tissue) is mounted
on, rather than in, a bone. Although the member may be mounted on
the bone, the attachment mechanisms for securing the member to the
bone are frequently secured in a bone tunnel. For example, and
referring now to FIG. 2, to mount a ligament L on a bone N, the
surgeon may create a bone tunnel B.sub.3 in the bone N and then
insert a suture anchor A in the bone tunnel so that the suture
anchor's sutures S extend out of the bone tunnel. Thereafter, the
sutures S may be used to secure the ligament L to the bone in ways
well known in the art, e.g., by tying a knot K atop a washer W.
Again, secure attachment of the anchor A in the bone tunnel depends
on the quality and integrity of the side wall of the bone tunnel,
as well as the effectiveness of the attachment mechanism of the
anchor.
[0006] Typically, the surface and integrity of a bone is not highly
predictable. For example, a bone does not have constant consistency
and hardness throughout. Typically, a bone has a hard cortical
outer shell and a soft cancellous inner core. The shell is
relatively thin as compared with the core, especially in large
bones such as the tibia and femur. This is significant because,
when a member (both tissue and non-tissue) is attached to a bone by
means of a bone tunnel, a significant portion of the attachment
typically occurs in the soft cancellous bone. Thus, the quality of
the attachment is typically heavily dependent on the quality of the
cancellous bone defining the side walls of the bone tunnel. The
quality of the cancellous core varies significantly from person to
person and bone to bone.
[0007] To achieve a high-quality attachment, the cancellous bone
tunnel must provide a high-quality surface and integrity. If the
side wall of the bone tunnel provides a poor-quality surface, for
example with too many fractures and/or striations, the member may
not be well secured to the bone. Similarly, if the side wall of the
bone tunnel provides poor integrity, e.g., an integrity like
unpacked snow, the member also may not be well secured to the
bone.
[0008] Furthermore, where a ligament is being mounted directly in
one or more bone tunnels (e.g., such as in the ligament
reconstruction depicted in FIG. 1), it is generally important that
the ligament osseo-integrate with the side wall(s) of the bone
tunnel(s). If the side wall of a bone tunnel provides a
poor-quality surface or poor integrity, such osseo-integration will
be impeded.
[0009] To enhance high-quality attachment in a bone tunnel,
surgeons have developed a procedure to enhance the quality and
integrity of the side wall of the bone tunnel. This is done by
dilating the bone tunnel so as to enhance the density of the bone
forming the side wall of the bone tunnel. More particularly, such
dilation involves packing the soft cancellous bone outward, in a
fashion similar to compacting soft snow. Such prior art dilation
typically involves drilling a hole of a pre-determined size into
the bone. The drill is typically then removed and a dilator,
slightly larger than the aforementioned pre-determined size, is
forced through the hole, commonly by hammering. As the dilator
advances through the hole, the dilator pushes interfering
cancellous bone radially outward. The dilator also pushes the
interfering cancellous bone distally.
[0010] Because the prior art dilation process typically involves
intermittent, sudden forward surges of the dilator, the process is
traumatic and may result in inconsistent compacting of the bone.
This inconsistent compacting of the bone can also cause the quality
and integrity of the side wall of the bone tunnel to vary. Surge
advancement also increases the potential for the dilator to assume
a path which may be aligned with the direction of the
dilator-driving force, rather than the path defined by the original
bone hole. In this respect it should be appreciated that an
incorrectly-located bone tunnel may cause significant mis-alignment
of a ligament attached therein. This can be especially true in the
case of an ACL or PCL reconstruction, where such mis-alignment can
have serious, long-term, debilitating consequences for the
patient.
[0011] Thus, what is needed is a novel dilator that accurately
advances through a bone and dilates a bone tunnel in a gentle,
controlled manner.
SUMMARY OF THE INVENTION
[0012] The present invention is a threaded bone tunnel dilator that
accurately advances through a bone and dilates a bone tunnel in a
gentle, controlled manner. The invention is applicable to any
attachment in a bone tunnel or bone canal. The invention provides
for progressively expanding a bone tunnel or canal laterally,
without significant expansion longitudinally. The invention also
provides for dilating a bone tunnel in a gentle, yet extensive
manner, without substantial drilling or cutting. The invention also
provides for defining a compacted bone tunnel with a smooth or
textured surface. The invention provides improved elements and
arrangements thereof, in an apparatus and method for the purposes
described, which are inexpensive, dependable, and effective in
accomplishing its intended purposes.
[0013] An embodiment configured according to the principles of the
present invention includes a distal, tapered threaded tip and a
body mounted on the distal end of a shaft. The proximal end of the
shaft includes a drive attachment for rotating the dilator so as to
threadingly advance the dilator through bone. The dilator is
preferably cannulated so that it can be advanced along a
guidewire.
[0014] In one preferred method of use, the surgeon first drives a
guidewire into the bone. Once the guidewire is emplaced, the
surgeon places the dilator over the guidewire, advances the dilator
along the guidewire, and engages the bone. Rotating the dilator
clockwise threadingly advances the dilator through the bone, until
the dilator reaches a desired depth. The tapered leading threads of
the dilator open the bone through dilation so as to define the bone
tunnel. The trailing smooth cylindrical body smoothes and further
compacts the side wall of the bone tunnel. After reaching the
desired depth, the surgeon removes the dilator by rotating the
dilator counterclockwise so as to threadingly retract the dilator
from the then-compacted bone tunnel.
[0015] These and other features of the present invention will be
more readily appreciated in view of the attached drawings and the
detailed description provided below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention is described in detail below with reference to
the following drawings, throughout which similar reference
characters denote corresponding features, and wherein:
[0017] FIG. 1 a schematic side view showing a graft ligament
attached to a femur and tibia;
[0018] FIG. 2 is a schematic side view showing a suture anchor
securing a ligament to a bone;
[0019] FIG. 3 is a side elevational view of a threaded dilator
formed in accordance with the present invention;
[0020] FIG. 4 is a side elevational view of another form of dilator
formed in accordance with the present invention;
[0021] FIG. 5 is a side elevational view of yet another form of
dilator formed in accordance with the present invention;
[0022] FIG. 6 is a side elevational view of an additional form of
dilator formed in accordance with the present invention;
[0023] FIG. 7 is a front view of the embodiment of FIG. 6;
[0024] FIG. 8 is a rear view of the embodiment of FIG. 6; and
[0025] FIG. 9 is a view like that of FIG. 6, except that the
dilator has been rotated 900 in a counterclockwise direction.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The present invention is a threaded bone tunnel dilator that
accurately advances through a bone and dilates a bone tunnel in a
gentle, controlled manner.
[0027] Referring now to FIG. 3, there is shown a dilator 5 which
comprises a preferred form of the invention. Dilator 5 generally
comprises a distal threaded tip 100 and a body 200 mounted on the
distal end of a shaft 300. The proximal end of the shaft 300
includes a drive attachment 400 for rotating the dilator so as to
threadingly advance the dilator.
[0028] The tip 100 is configured so as to have a taper 105. The
taper 105 causes the dilator to open the bone and to be
self-centering during bone tunnel dilation. This self-centering
feature is especially helpful when the invention is not used in
conjunction with a guidewire. To this end, the taper 105 is
preferably about 5 to about 30 degrees with respect to the
longitudinal axis 110. In one preferred embodiment of the
invention, the taper 105 is preferably about 10.85 degrees with
respect to the longitudinal axis 110. To achieve this taper of
about 10.85 degrees, in one preferred embodiment of the invention,
the distal end 120 of tip 100 has a diameter 125 of about 0.128
inches, the proximal end 130 of tip 100 has a diameter 135 of about
0.354 inches, and the length 137 between the two diameters 125 and
135 of about 0.381 inches. However, it should also be appreciated
that the taper 105 may be adjusted to any angle which may be more
appropriate for a particular application.
[0029] The taper 105 may also assume any profile which promotes
optimal bone compaction. For example, the taper 105 may be a
straight taper as shown. The taper 105 also may be a compound
taper, consisting of different straight tapers defining unique
angles with respect to the longitudinal axis 110 of tip 100.
Alternatively, the taper 105 may also assume a parabolic or
elliptical shape, or define diverse arc segments, etc.
[0030] The distal end 120 of tip 100 has a chamfer 138 that defines
an angle 139 relative to the longitudinal axis 110. The chamfer 138
ensures that burrs caused by machining are not present at the end
of the dilator which may abrade soft cancellous bone. In one
preferred form of the invention, the angle 139 of chamfer 138 is
approximately 60 degrees.
[0031] The tip 100 has threads 140 which are configured so as to
draw the dilator through bone and simultaneously compact the soft
cancellous bone coming into contact with the threads 140. In one
form of the invention, threads 140 advance the dilator through, and
compact, the bone so as to create a bone tunnel in the bone. The
threads 140 are preferably consistent along, and correspond to, the
taper 105. In one preferred form of the invention, the threads 140
have a pitch 145 of about 0.060 to about 0.120 inches, and
preferably about 0.080 inches. Inasmuch as the threads 140 are
intended to dilate rather than cut bone, the threads are devoid of
cutting flutes. As a result, the relatively blunt threads 140
displace, rather than cut, bone.
[0032] The body 200 is, preferably, cylindrical in shape, and
preferably has a length 205 of about 0.406 inches. The distal end
210 of the body 200 has a threaded portion 215 comprising threads
220. The threads 140 of tip 100 continue, in a continuous fashion,
as the threads 220 on the threaded portion 215 of body 200. In the
case where the tip 100 defines a single, straight taper, the
troughs of threads 220 continue to enlarge radially until they run
out. However, the peaks of the threads 220 do not extend radially
beyond, and are truncated along, an axial projection of the
diameter 230 of the proximal unthreaded portion 231 of body 200.
The peaks of the threads 220 of body 200 also may be truncated at a
radial distance less than the axial projection of the proximal
unthreaded portion 231, if desired.
[0033] In either case, the proximal unthreaded portion 231 defines
the widest portion of the dilator which is to enter the bone. Thus,
the proximal unthreaded portion 231 is the last surface of the
dilator that engages (and hence forms) the side wall of the bone
tunnel. Accordingly, the quality of the surface of the proximal
unthreaded portion 231 significantly influences the surface quality
of the resultant bone tunnel. If a smooth bone tunnel surface is
desired, the surface of the proximal unthreaded portion 231 should
be completely smooth so as to not create a helical pattern of any
sort in the bone tunnel wall while the dilator threadingly advances
into, or withdraws from, the bone. The proximal unthreaded portion
231 also may include any number of projections or shape-forming
structures thereon so as to impart a desired pattern in the side
wall of the bone tunnel which is being formed. To that end, body
200, tip 100 and threads 140 and 220 may be finished to a desired
surface by polishing, coating or particularized machining.
[0034] The shaft 300 has a distal end 305 and a proximal end 310.
The shaft 300 also may have indicia (not shown) such as depth marks
or the like to aid in determining the dilator's penetration into a
bone. The shaft 300 has a diameter 315 that may be the same as the
diameter 230 of the proximal unthreaded portion 231 of body 200.
Preferably, however, shaft 300 has a diameter 315 which is less
than the diameter 230 of the proximal unthreaded portion 231 of
body 200. Where the diameter 315 is less than the diameter 230, the
junction 320 should be machined so that, during removal of the
dilator from a compacted bone tunnel, no sharp proximal edge exists
that may abrade the bone tunnel wall. Preferably, the junction
defines an arced surface 325. However, any suitably-shaped surface
which does not defeat the purposes of the invention may also be
used.
[0035] The shaft 300 terminates in a proximal drive connector 400
which is adapted to connect with a manual or powered rotary driver
(not shown). Preferably, the drive connector has a hexagonal-shaped
or square-shaped cross-section. Alternatively, the drive connector
may define a handle (not shown) for manual rotational driving.
[0036] Preferably, but not necessarily, tip 100, body 200 and shaft
300 are cannulated with a center bore 500. The cannulation is
configured to receive a guidewire appropriate for dilation, as
described below. In one preferred form of the invention, center
bore 500 has a diameter of approximately 0.158 inches.
[0037] With the foregoing dilator, the preferred method of use does
not involve pre-drilling or otherwise creating a sized hole in the
bone.
[0038] In one preferred method of use, the surgeon drives a
guidewire, such as a 2.4 mm K-wire, into the bone. Once the
guidewire is positioned in the bone, the surgeon places the tip of
cannulated dilator 5 over the guidewire. The surgeon then advances
dilator 5 along the guidewire until the distal tip of the dilator
engages the bone. Then the surgeon rotates dilator 5 clockwise so
as to threadingly advance the dilator through the bone, until the
dilator reaches a desired depth. Reaching the desired depth could
be ascertained, for example, from indicia (not shown) on the shaft
of the dilator. As dilator 5 follows the guidewire into the bone,
the dilator drives interfering bone laterally, thereby opening a
bone tunnel into the bone through dilation. After reaching the
desired depth, the surgeon removes dilator 5 by rotating the
dilator counterclockwise and retracting the dilator from the
then-compacted bone tunnel.
[0039] This method creates a bone tunnel by dilation, without any
substantial cutting or drilling of the bone. The method also can be
practiced so as to cause significant compaction. For example, in
the case where a 2.4 mm guidewire is used to define the path for
the dilator, and a 10 mm dilator is used to dilate the bone along
the path of the guidewire, the dilator provides a radial dilation
(or compaction) of 3.8 mm about the circumference of the
guidewire.
[0040] While dilator 5 can achieve substantial bone compaction, the
dilator also compacts the bone gradually and gently because the
peaks and troughs of its threads expand gradually. Specifically, as
dilator 5 is rotated so as to advance the dilator through the bone,
the bone is engaged by a thread peak that gradually expands. Thus,
as the dilator advances through the bone, the portion of bone
contacted by the thread peak will be gradually pushed outwardly as
the thread peak progressively enlarges along the dilator's taper.
As discussed above, radial thread peak expansion is limited within
an axial projection of the proximal unthreaded portion 231 of body
200.
[0041] Just as bone contacted by the thread peak is gradually
radially compacted, bone received in the thread trough is also
gradually compacted an equivalent amount. As the dilator advances
through the bone, the trough radially expands in a manner
corresponding to taper 105. Thus, the portion of bone encountering
the thread trough will also be gradually pushed outwardly. As
described above, the dilator's threads begin at the distal end of
tip 100 and run out on the distal portion of body 200. Just as the
thread peak is limited by an axial projection of the unthreaded
portion 231 of body 200, the thread trough also expands until it is
co-extensive with the unthreaded portion 231. Naturally, if the
thread peaks are truncated radially inward of the axial projection
of the body, the thread trough also will be so limited.
[0042] As a result, bone contacted by the thread peaks, thread
troughs, and the portions of the thread between the peaks and
troughs, all are dilated and compacted in the same amount. The
resultant bone tunnel exhibits even compaction along the length of
the bone tunnel.
[0043] Although preferred, the dilator does not have to be
cannulated. Instead, the dilator may be introduced into a small
pilot hole formed in the bone. As the dilator threadingly and
controllingly advances along the pilot hole, the dilator will
accurately follow the path of the pilot hole in the bone and will
not veer off course, as can be the case with prior art non-threaded
dilators. This is due to the novel threaded taper of the present
dilator 5, which induces the dilator to align itself as the dilator
advances through the pilot hole.
[0044] The present dilator may assume other configurations which
render it more effective in dilating bone tunnels. For example, and
referring now to FIG. 4, the body 600 may have a proximal linear
taper 605, rather than the cylindrical shape of body 200. And
referring next to FIG. 5, the body 700 may have a proximal arcuate
flare 705. These configurations, and others not mentioned, may be
employed to further displace the cancellous bone of the bone tunnel
or contour the bone tunnel in a desirable manner.
[0045] Referring next to FIGS. 6-9, an additional embodiment 800 of
the invention primarily dilates a bone tunnel, but also has a
distal cutting flute 805 and/or a proximal cutting flute 810.
[0046] The distal cutting flute 805 aids in opening a passage
through which the dilator 800 passes while forming a bone tunnel.
More particularly, when the dilator 800 is dilating a bone tunnel,
it threadingly advances through the bone tunnel, in a clockwise
manner. As the dilator 800 rotates, the sharp edge 815 of the
distal flute 805 cuts away soft cancellous bone encountered as the
dilator 800 advances. Cutting away this inner-most bone matter of
the passage facilitates passage of the dilator into the bone.
[0047] The proximal cutting flute 810 aids in removing the dilator
800 from a bone tunnel following dilation of the bone tunnel. More
particularly, when the dilator 800 is removed from the bone tunnel,
it threadingly withdraws from the bone tunnel, in a
counterclockwise manner. As the dilator 800 threadingly withdraws,
the sharp edge 820 of the proximal flute 810 cuts away any soft
cancellous bone that may spring back into the bone tunnel following
dilation, and/or any other bone matter that may encumber removal of
the dilator from the bone tunnel. Cutting away this encroaching
bone matter reduces resistance to removing the dilator 800 from the
dilated bone tunnel.
[0048] It should be appreciated that distal cutting flute 805 is
configured so that it will only cut bone while the dilator is
advancing into the bone, and proximal cutting flute 810 is
configured so that it will only cut bone while the dilator is
withdrawing from bone.
[0049] To aid in determining whether the dilator is imparting an
appropriate level of compaction and/or dilating in a sufficiently
gentle manner, the dilator may include, or may be adaptable for
connection to, a torque indicator to ascertain the amount of torque
or stress that dilation is causing.
[0050] The invention is not limited to the foregoing, but also
encompasses all improvements and substitutions consistent with the
principles of the invention.
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