U.S. patent application number 11/672539 was filed with the patent office on 2007-06-07 for percutaneous access devices and bone anchor assemblies.
Invention is credited to Erasmo Lopez, Ramon Ruberte, Christopher Sicvol.
Application Number | 20070129731 11/672539 |
Document ID | / |
Family ID | 34654213 |
Filed Date | 2007-06-07 |
United States Patent
Application |
20070129731 |
Kind Code |
A1 |
Sicvol; Christopher ; et
al. |
June 7, 2007 |
Percutaneous Access Devices And Bone Anchor Assemblies
Abstract
A percutaneous access device includes an inner tube and an outer
tube disposed about at least a portion of the inner tube. The outer
tube may be sized to span from a skin incision in a patient to a
site proximate the spine of the patient. The distal end of the
outer tube may be adapted to releasably engage a bone anchor. The
inner tube may be adjustable relative to the outer tube between a
first position and a second position in which the distal end of the
inner tube contacts the bone anchor. A bone anchor assembly
includes a bone anchor having a distal bone engaging portion and a
receiving member having a recess for receiving a spinal fixation
element. The proximal end of the receiving member may have an
arcuate groove formed on an exterior surface thereof to facilitate
connection of an instrument to the receiving member.
Inventors: |
Sicvol; Christopher;
(Boston, MA) ; Lopez; Erasmo; (Seattle, WA)
; Ruberte; Ramon; (Ann Arbor, MI) |
Correspondence
Address: |
PHILIP S. JOHNSON;JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
34654213 |
Appl. No.: |
11/672539 |
Filed: |
February 8, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10738286 |
Dec 16, 2003 |
7179261 |
|
|
11672539 |
Feb 8, 2007 |
|
|
|
Current U.S.
Class: |
606/104 |
Current CPC
Class: |
A61B 17/70 20130101;
A61B 17/7035 20130101; A61B 17/708 20130101; A61B 2017/564
20130101; A61B 17/7034 20130101; A61B 17/7037 20130101; A61B
2090/037 20160201; A61B 17/7032 20130101; A61B 17/7076 20130101;
A61B 17/8605 20130101; A61B 17/7091 20130101 |
Class at
Publication: |
606/104 |
International
Class: |
A61F 2/00 20060101
A61F002/00 |
Claims
1. A percutaneous access device comprising: an inner tube having a
proximal end, a distal end, and a lumen extending between the
proximal end; and an outer tube disposed about at least a portion
of the inner tube, the outer tube having a proximal end, a distal
end, and a lumen extending between the proximal end and the distal
end, the outer tube being sized to span from at least a skin
incision in a patient to a predetermined site proximate the spine
of the patient, the distal end of the outer tube being adapted to
releasably engage a bone anchor, the inner tube being adjustable
relative to the outer tube along the longitudinal axis of the outer
tube between a first position and a second position in which the
distal end of the inner tube contacts the bone anchor.
2. The percutaneous access device of claim 1, wherein the lumen of
the inner tube has an inner diameter proximate the distal end of
the inner tube that is greater than or equal to an inner diameter
of a bore formed in a receiving portion of the bone anchor.
3. The percutaneous access device of claim 1, wherein the outer
tube has an outer diameter proximate the distal end of the outer
tube that is less than or equal to an outer diameter of a receiving
portion of the bone anchor.
4. The percutaneous access device of claim 1, wherein the inner
tube and the outer tube are coaxial.
5. The percutaneous access device of claim 1, wherein the inner
tube has a first slot formed therein, the first slot having an
opening at the distal end of the inner tube and extending a first
slot length toward the proximal end of the inner tube.
6. The percutaneous access device of claim 5, wherein the outer
tube has a second slot formed therein, the second slot having an
opening at the distal end of the outer tube and extending a second
slot length toward the proximal end of the outer tube.
7. The percutaneous access device of claim 6, wherein the first
slot is aligned with the second slot.
8. The percutaneous access device of claim 6, wherein the first
slot length is sized to be accessible external to the skin
incision.
9. The percutaneous access device of claim 6, wherein the first
slot and the second slot each has a width that is approximately
equal to the width of a recess formed in the receiving member of
the bone anchor.
10. The percutaneous access device of claim 1, wherein the distal
end of the outer tube includes a pair of opposed tabs, each tab
having a radially inward projection that is sized and shaped to
seat within a groove formed in a receiving member of a bone
anchor.
11. The percutaneous access device of claim 10, wherein each tab
has a tab width that is less than or equal to the width of a slot
formed in the receiving member of the bone anchor.
12. The percutaneous access device of claim 1, wherein the distal
end of the inner tube defines a plurality of contact surfaces, each
contact surface contacting a proximal surface of a receiving member
of the bone anchor when the inner tube is in the second
position.
13. The percutaneous access device of claim 12, wherein an
extension extends axially from at least one of the contact
surfaces, the extension engaging the bone anchor to inhibit
rotation of the inner tube relative to the bone anchor when the
inner tube is in the second position.
14. A bone anchor assembly, comprising: a bone anchor having a
proximal head and a distal bone engaging portion; and a receiving
member coupled to the bone anchor, the receiving member having a
proximal end, a distal end and a recess for receiving a spinal
fixation element, the proximal end of the receiving member having
at least one arcuate groove formed on an exterior surface thereof
to facilitate connection of an instrument to the receiving
member.
15. The bone anchor assembly of claim 14, wherein the proximal end
has a first bore defining a first bore axis, the recess is in
communication with the first bore, the distal end has a second bore
opposite the first bore and defining a second bore axis, and the
second bore is sized to receive the head of the bone anchor.
16. The bone anchor assembly of claim 15, wherein the first bore
axis and the second bore axis are coaxial.
17. The bone anchor assembly of claim 15, wherein the second bore
axis is at an angle other than 0 degrees relative to the first bore
axis.
18. The bone anchor assembly of claim 15, wherein the bone anchor
is adjustable relative to the receiving member.
19. The bone anchor assembly of claim 15, wherein the receiving
member has a substantially U-shaped cross-section defined by two
legs separated by the recess, each leg being free at the proximal
end of the receiving member.
20. The bone anchor assembly of claim 19, wherein the at least one
arcuate groove is formed on an exterior surface of the proximal end
of one of the legs.
21. The bone anchor assembly of claim 19, wherein a first arcuate
groove is formed on an exterior surface of the proximal end of a
first one of the legs and a second arcuate groove is formed on an
exterior surface of the proximal end of a second one of the
legs.
22. The bone anchor assembly of claim 14, wherein the arcuate
groove has a proximal surface and a distal surface.
23. The bone anchor assembly of claim 22, wherein the proximal
surface is oriented at angle greater than 0.degree. relative to an
orthogonal line that is oriented perpendicular to a longitudinal
axis of the receiving member.
24. The bone anchor assembly of claim 22, wherein the proximal
surface is oriented at angle between approximately 5.degree. and
approximately 30.degree. relative to an orthogonal line that is
oriented perpendicular to a longitudinal axis of the receiving
member.
25. The bone anchor assembly of claim 22, wherein the proximal
surface is oriented at angle of approximately 20.degree. relative
to an orthogonal line that is oriented perpendicular to a
longitudinal axis of the receiving member.
26. The bone anchor assembly of claim 22, wherein the distal
surface is oriented parallel to the groove plane.
27. The bone anchor assembly of claim 22, wherein the distal
surface is oriented at angle greater than 0.degree. relative to an
orthogonal line that is oriented perpendicular to a longitudinal
axis of the receiving member.
28. The bone anchor assembly of claim 14, wherein the bone anchor
is fixed relative to the receiving member.
29. The bone anchor assembly of claim 14, wherein the bone anchor
is at least one of a bone screw or a bone hook.
30. A bone anchor assembly, comprising: a bone anchor having a
proximal head and a distal bone engaging portion; and a receiving
member having a proximal end having a first bore, a distal end
opposite the proximal end and having a second bore, and a recess
for receiving a spinal fixation element in communication with the
first bore, the second bore being sized to receive the head of the
bone anchor, the receiving member having a substantially U-shaped
cross-section defined by two legs separated by the recess, each leg
being free at the proximal end of the receiving member, wherein a
first arcuate groove is formed on an exterior surface of the
proximal end of a first one of the legs and a second arcuate groove
is formed on an exterior surface of the proximal end of a second
one of the legs.
31. The bone anchor assembly of claim 30, wherein the first arcuate
groove has a proximal surface and a distal surface opposite the
proximal surface and the second arcuate groove has a proximal
surface and a distal surface opposite the proximal surface.
32. The bone anchor assembly of claim 31, wherein the proximal
surface of the first groove and the proximal surface of the second
groove are co-planar.
33. The bone anchor assembly of claim 31, wherein the proximal
surface of the first groove and the proximal surface of the second
groove each are oriented at angle greater than 0.degree. relative
to an orthogonal line that is oriented perpendicular to a
longitudinal axis of the receiving member.
34. The bone anchor assembly of claim 31, wherein the proximal
surface of the first groove and the proximal surface of the second
groove each are oriented at angle between approximately 5.degree.
and approximately 30.degree. relative to an orthogonal line that is
oriented perpendicular to a longitudinal axis of the receiving
member.
35. The bone anchor assembly of claim 31, wherein the proximal
surface of the first groove and the proximal surface of the second
groove each are oriented at angle of approximately 20.degree.
relative to an orthogonal line that is oriented perpendicular to
longitudinal axis of the receiving member.
36. The bone anchor assembly of claim 31, wherein the distal
surface of the first groove and the distal surface of the second
groove each are oriented at angle greater than 0.degree. relative
to an orthogonal line that is oriented perpendicular to a
longitudinal axis of the receiving member.
37. A percutaneous access device comprising: an inner tube having a
proximal end, a distal end, and a lumen extending between the
proximal end and the distal end, the inner tube having a first slot
formed therein, the first slot having an opening at the distal end
of the inner tube and extending a first slot length toward the
proximal end of the inner tube; and an outer tube coaxially
disposed about at least a portion of the inner tube, the outer tube
having a proximal end, a distal end, and a lumen extending between
the proximal end and the distal end; the outer tube being sized to
span from at least a skin incision in a patient to a predetermined
site proximate the spine of the patient, the distal end of the
outer tube being adapted to releasably engage a bone anchor, the
outer tube having a second slot formed therein aligned with the
first slot, the second slot having an opening at the distal end of
the outer tube and extending a second slot length toward the
proximal end of the outer tube.
38. The percutaneous access device of claim 37, wherein inner tube
is movable along the longitudinal axis of the outer tube.
39. The percutaneous access device of claim 37, wherein the inner
tube is movable between a between a first position and a second
position in which the distal end of the inner tube contacts the
bone anchor.
40. The percutaneous access device of claim 37, wherein the first
slot length and the second slot length are approximately equal.
41. The percutaneous access device of claim 40, wherein the first
and second slots lengths are selected to span from at least a skin
incision in patient to the proximal end of the inner tube and the
outer tube, respectively.
42. A medical device comprising: a percutaneous access device
comprising an inner tube having a proximal end, a distal end, and a
lumen extending between the proximal end and the distal end; and an
outer tube disposed about at least a portion of the inner tube, the
outer tube having a proximal end, a distal end, and a lumen
extending between the proximal end and the distal end; the outer
tube being sized to span from at least a skin incision in a patient
to a predetermined site proximate the spine of the patient; and a
bone anchor assembly comprising: a bone anchor having a proximal
head and a distal bone engaging portion; and a receiving member
coupled to the bone anchor, the receiving member having a proximal
end, a distal end and a recess for receiving a spinal fixation
element, the proximal end of the receiving member having at least
one arcuate groove formed on an exterior surface thereof, wherein
the distal end of the outer tube is adapted to releasably engage
the arcuate groove in the receiving member.
43. The medical device of claim 42, wherein the inner tube is
adjustable relative to the outer tube along the longitudinal axis
of the outer tube between a first position and a second position in
which the distal end of the inner tube contacts the proximal end of
the receiving member.
44. A medical device comprising: a percutaneous access device
comprising an inner tube having a proximal end, a distal end, and a
lumen extending between the proximal end and the distal end, the
inner tube having a first slot formed therein, the first slot
having an opening at the distal end of the inner tube and extending
toward the proximal end of the inner tube, and an outer tube
coaxially disposed about at least a portion of the inner tube, the
outer tube having a proximal end, a distal end, and a lumen
extending between the proximal end and the distal end, the outer
tube being sized to span from at least a skin incision in a patient
to a predetermined site proximate the spine of the patient, the
outer tube having a second slot formed therein aligned with the
first slot, the second slot having an opening at the distal end of
the outer tube and extending toward the proximal end of the outer
tube; and a bone anchor assembly comprising a bone anchor having a
proximal head and a distal bone engaging portion, and a receiving
member having a proximal end having a first bore, a distal end
opposite the proximal end and having a second bore, and a recess
for receiving a spinal fixation element and in communication with
the first bore, the second bore being sized to receive the head of
the bone anchor, wherein the distal end of the outer tube is
adapted to releasably engage the receiving member and the first and
second slots are aligned with the recess in the receiving member
when the outer tube is releasably engaged to the receiving
member.
45. The medical device of claim 44, wherein the receiving member
has a substantially U-shaped cross-section defined by two legs
separated by the recess and each leg is free at the proximal end of
the receiving member.
46. The medical device of claim 45, wherein a first arcuate groove
is formed on an exterior surface of the proximal end of a first one
of the legs and a second arcuate groove is formed on an exterior
surface of the proximal end of a second one of the legs and the
distal end of the outer tube is configured to releasably engage the
first and second grooves.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/738,286, filed Dec. 16, 2003, which is
incorporated herein by reference.
BACKGROUND
[0002] For a number of known reasons, spinal fixation devices are
used in orthopedic surgery to align and/or fix a desired
relationship between adjacent vertebral bodies. Such devices
typically include a spinal fixation element, such as a relatively
rigid fixation rod or plate, that is coupled to adjacent vertebrae
by attaching the element to various anchoring devices, such as
hooks, bolts, wires, or screws. The fixation elements can have a
predetermined contour that has been designed according to the
properties of the target implantation site, and once installed, the
fixation element holds the vertebrae in a desired spatial
relationship, either until desired healing or spinal fusion has
taken place, or for some longer period of time.
[0003] Spinal fixation elements can be anchored to specific
portions of the vertebrae. Since each vertebra varies in shape and
size, a variety of anchoring devices have been developed to
facilitate engagement of a particular portion of the bone. Pedicle
screw assemblies, for example, have a shape and size that is
configured to engage pedicle bone. Such screws typically include a
threaded shank that is adapted to be threaded into a vertebra, and
a head portion having a rod-receiving element, usually in the form
of a U-shaped recess formed in the head. A set-screw, plug, or
similar type of closure mechanism is used to lock the fixation
element, e.g., a spinal rod, into the rod-receiving head of the
pedicle screw. In use, the shank portion of each screw is threaded
into a vertebra, and once properly positioned, a rod is seated
through the rod-receiving member of each screw and the rod is
locked in place by tightening a cap or other closure mechanism to
securely interconnect each screw and the fixation rod.
[0004] Recently, the trend in spinal surgery has been moving toward
providing minimally invasive devices and methods for implanting
bone anchors and spinal fixation devices.
SUMMARY
[0005] Disclosed herein are percutaneous access devices that
facilitate the delivery and implanting of bone anchors into bone,
in particular, one or more vertebral bodies of the spine. In
particular, the disclosed percutaneous access devices permit the
delivery and implanting of one or more bone anchors in a minimally
invasive manner thereby limiting trauma to surrounding tissue.
Moreover, the percutaneous access devices disclosed herein can
provide a percutaneous pathway between a skin incision and the bone
anchor that may be used to deliver components of the bone anchor,
such as the fastening mechanism, the fixation element, and/or
instruments to the bone anchor. Also, disclosed herein are bone
anchors that facilitate the connection of instruments, such as a
percutaneous access device, to the bone anchor.
[0006] In accordance with one exemplary embodiment, a percutaneous
access device includes an inner tube and an outer tube disposed
about at least a portion of the inner tube. The outer tube, in the
exemplary embodiment, is sized to span from at least a skin
incision in a patient to a predetermined site proximate the spine
of the patient. The distal end of the outer tube may be adapted to
releasably engage a bone anchor. The inner tube, in the exemplary
embodiment, may be adjustable relative to the outer tube along the
longitudinal axis of the outer tube between a first position and a
second position in which the distal end of the inner tube contacts
the bone anchor.
[0007] In accordance with another exemplary embodiment, a bone
anchor assembly includes a bone anchor having a proximal head and a
distal bone engaging portion and a receiving member coupled to the
bone anchor. The receiving member, in the exemplary embodiment, may
have a proximal end, a distal end and a recess for receiving a
spinal fixation element, such as a rod or a plate. The proximal end
of the receiving member, in the exemplary embodiment, may have at
least one arcuate groove formed on an exterior surface thereof to
facilitate connection of an instrument, such as a percutaneous
access device, to the receiving member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] These and other features and advantages of the percutaneous
access devices and bone anchor assemblies disclosed herein will be
more fully understood by reference to the following detailed
description in conjunction with the attached drawings in which like
reference numerals refer to like elements through the different
views. The drawings illustrate principles of the percutaneous
access devices and bone anchor assemblies disclosed herein and,
although not to scale, show relative dimensions.
[0009] FIG. 1 is a perspective view of an exemplary embodiment of a
percutaneous access device;
[0010] FIG. 2 is a perspective view of the components of the
percutaneous access device of FIG. 1;
[0011] FIG. 3 is a perspective view of the distal end of the
percutaneous access device of FIG. 1;
[0012] FIG. 4 is a perspective view of the distal end of the
percutaneous access device of FIG. 1 coupled to an exemplary
embodiment of a bone anchor assembly;
[0013] FIG. 5 is a side elevational view of the bone anchor
assembly of FIG. 4;
[0014] FIG. 6 is a side elevational view of the receiving member of
the bone anchor assembly of FIG. 4;
[0015] FIG. 7 is a side elevational view in cross-section of the
distal end of the percutaneous access device of FIG. 1 coupled to
the receiving member of the bone anchor assembly of FIG. 4;
[0016] FIG. 8 is a side elevational view in cross-section of the
distal end of the outer tube of the percutaneous access device of
FIG. 1 and the receiving member of the bone anchor assembly of FIG.
4;
[0017] FIGS. 9 and 10 are side elevational views in cross section
of the distal end of the inner tube of the percutaneous access
device of FIG. 1 and the receiving member of the bone anchor
assembly of FIG. 4;
[0018] FIGS. 11A-11D are perspective views of the distal end of the
percutaneous access device of FIG. 1 and the receiving member of
the bone anchor assembly of FIG. 4, illustrating exemplary steps
for releasably coupling the distal end of the percutaneous access
device to the receiving member of the bone anchor assembly;
[0019] FIG. 12 is a side elevational view an another exemplary
embodiment of a bone anchor assembly;
[0020] FIG. 13 is a side elevational view of the receiving member
of the bone anchor assembly of FIG. 12;
[0021] FIG. 14 is a side elevational view in cross section of the
receiving member of the bone anchor assembly of FIG. 12;
[0022] FIG. 15 is a side elevational view in cross section of an
arcuate groove of the receiving member of the bone anchor assembly
of FIG. 12;
[0023] FIG. 16 is a side elevational view in cross-section of the
distal end of the another exemplary embodiment of a percutaneous
access device coupled to the receiving member of the bone anchor
assembly of FIG. 12;
[0024] FIGS. 17A and 17B are perspective views of an alternative
embodiment of a percutaneous access device and a bone anchor
assembly, illustrating a threaded connecting between the
percutaneous access device and the bone anchor assembly;
[0025] FIGS. 18A and 18B are perspective views of an alternative
embodiment of a percutaneous access device and a bone anchor
assembly, illustrating a plurality of externally threaded removable
tabs for releasable engagement with an instrument such as a
percutaneous access device;
[0026] FIGS. 19A-19D are perspective views of an alternative
embodiment of a percutaneous access device and a bone anchor
assembly, illustrating the percutaneous access device and the bone
anchor assembly interconnected by one or more internal wires;
[0027] FIGS. 20A-20D are perspective views of an alternative
embodiment of a percutaneous access device and a bone anchor
assembly, illustrating the percutaneous access device and the bone
anchor assembly interconnected by one or more external wires;
[0028] FIG. 21 is a perspective view of an alternative embodiment
of a bone anchor assembly having a plurality of removable tabs for
releasable engagement with an instrument such as a percutaneous
access device;
[0029] FIGS. 22A-22B are perspective views of an exemplary
embodiment of a percutaneous access device, illustrating axial
cut-outs provided in the outer tube of the percutaneous access
device; and
[0030] FIGS. 23A-23B are perspective views of an alternative
embodiment of a percutaneous access device and a bone anchor
assembly, illustrating flexible tabs provided on the distal end of
the percutaneous access device for releasable engagement with the
bone anchor assembly.
DETAILED DESCRIPTION
[0031] Certain exemplary embodiments will now be described to
provide an overall understanding of the principles of the
structure, function, manufacture, and use of the percutaneous
access devices and bone anchor assemblies disclosed herein. One or
more examples of these embodiments are illustrated in the
accompanying drawings. Those of ordinary skill in the art will
understand that the percutaneous access devices and bone anchor
assemblies specifically described herein and illustrated in the
accompanying drawings are non-limiting exemplary embodiments and
that the scope of the present invention is defined solely be the
claims. The features illustrated or described in connection with
one exemplary embodiment may be combined with the features of other
embodiments. Such modifications and variations are intended to be
included within the scope of the present invention.
[0032] The articles "a" and "an" are used herein to refer to one or
to more than one (i.e. to at least one) of the grammatical object
of the article. By way of example, "an element" means one element
or more than one element.
[0033] The term "distal" as used herein with respect to any
component or structure will generally refer to a position or
orientation that is proximate, relatively, to the bone surface to
which a bone anchor is to be applied. Conversely, the term
"proximal" as used herein with respect to any component or
structure will generally refer to a position or orientation that is
distant, relatively, to the bone surface to which a bone anchor is
to be applied.
[0034] The terms "comprise," "include," and "have," and the
derivatives thereof, are used herein interchangeably as
comprehensive, open-ended terms. For example, use of "comprising,"
"including," or "having" means that whatever element is comprised,
had, or included, is not the only element encompassed by the
subject of the clause that contains the verb.
[0035] FIGS. 1-5 illustrate an exemplary embodiment of a
percutaneous access device 10. The exemplary percutaneous access
device 10 can facilitate the delivery and implanting of a bone
anchor, such as the exemplary bone anchor assembly 100 illustrated
and described below, into bone, in particular, one or more
vertebral bodies of the spine. In particular, the exemplary
percutaneous access device 10 can facilitate the delivery and
implanting of a bone anchor in a minimally invasive manner and can
provide a percutaneous pathway between a skin incision in the
patent and the bone anchor that may be used to deliver components
of the bone anchor, such as the closure mechanism, one or more
fixation elements, and/or instruments to the bone anchor. The
percutaneous access device 10 is preferably adapted to be
introduced through a minimally invasive percutaneous incision,
which is a relatively small incision that typically has a length
less than the diameter or width of the device being inserted
therethrough. Although the exemplary percutaneous access device 10
described below is designed primarily for use in spinal
applications, one skilled in the art will appreciate that the
exemplary percutaneous access device 10, as well as the other
exemplary embodiments described below, may be used to facilitate
the implantation of any type of bone anchor to any type of
bone.
[0036] The exemplary percutaneous access device 10 includes an
inner tube 12 and an outer tube 14 disposed about at least a
portion of the inner tube 12. In the illustrated exemplary
embodiment, the outer tube 14 is coaxially disposed about the inner
tube 12 such that the inner tube 12 and the outer tube 14 share a
common longitudinal axis 16. One skilled in the art will
appreciate, however, that the outer tube 14 and inner tube 12 need
not be coaxially aligned. The inner tube 12 and the outer tube 14,
in the exemplary embodiment, are generally cylindrical in shape,
having an approximately circular cross-section. One skilled in the
art will appreciate, however, the inner tube 12 and the outer tube
14 may have other cross-sectional shapes, including, for example,
elliptical or rectilinear. In the exemplary embodiment, the inner
tube 12 and outer tube 14 have analogous cross-sections, however,
one skilled in the art will appreciate the inner tube 12 and the
outer tube 14 can have different cross-sectional shapes. The axial
length of the inner tube 12 and outer tube 12 may vary depending
on, for example, the patient anatomy, the procedures employed,
and/or, that area of the spine in which the device 10 is employed.
The inner tube 12 and the outer tube 14 may be linear, as in the
exemplary embodiment, or may curved or angled along one or more
sections or the entire length thereof. The inner tube 12 and the
outer tube 14 may be constructed from any suitable biocompatible
material, including, for example, a metal, such as stainless steel,
or a polymer, from any conventional method of manufacturing medical
devices.
[0037] Although the illustrated exemplary embodiment includes an
inner tube and an outer tube, one skilled in the art will
appreciate that any number of tubes, e.g., one or more tubes, may
be employed depending on, for example, the type of bone anchor
employed and the manner by which the device is releasably engaged
to the bone anchor. For example, exemplary embodiments of a
percutaneous access device having a single outer tube are described
below.
[0038] Continuing to refer to FIGS. 1-5, the inner tube or sleeve
12 includes a proximal end 20, a distal end 22, and a lumen 24
extending between the proximal end 20 and the distal end 22. The
lumen 24 extends the length of the inner tube 12 and defines a
longitudinal axis 26 of the inner tube 12. The outer tube or sleeve
14 includes a proximal end 30, a distal end 32, and a lumen 34
extending between the proximal end 30 and the distal end 32. The
lumen 34 may extend the length of the outer tube 14 and defines a
longitudinal axis 36 of the outer tube 14. The inner tube 12 in
positionable within the lumen 36 of the outer tube 14. In the
exemplary percutaneous access device 10, the inner tube 12 is
longitudinally adjustable with respect to the outer tube 14. For
example, the inner tube 12 may adjustable from a first, proximal
position, in which the distal end 22 of the inner tube 12 is
positioned proximal to the distal end 32 of the outer tube 14 as
illustrated in FIG. 3, and a second, distal position, in which the
distal end 22 of the inner tube 12 is positioned proximate to the
distal end 32 of the outer tube 14. In the exemplary embodiment,
the distal end 22 of the inner tube 12 preferably contacts at least
a portion of the bone anchor assembly when the inner tube 12 is in
the second position, as illustrated in FIGS. 4 and 7 and as
discussed in more detail below.
[0039] The exemplary percutaneous access device 10 may include an
adjustment mechanism 40 that allows an operator to adjust the
relative longitudinal position of the inner tube 12 and the outer
tube 14. In the illustrated embodiment, for example, the adjustment
mechanism 40 is a hollow, tubular shaped cap 41 having internal
threads 42 that engage external threads 44 provided on the proximal
end 30 of the outer tube 14. The threads 42, 44 allow the cap 41 to
be longitudinal adjusted relative to the outer tube 14. In the
exemplary embodiment, the inner tube 12 is connected to the cap 41
and, thus, can move with cap 41 as the cap 41 is advanced or
withdrawn relative to the outer tube 14. For example, the proximal
end 30 of the inner tube 12 of the exemplary embodiment may include
one or more resilient tabs 46, one or more of which may have a
projection 48 that seats within an annular grove provided on the
interior surface of the cap 41 to thereby connect the proximal end
30 of the inner tube 12 to the cap 41. In the illustrated
embodiment, two resilient tabs 46 are provided on opposite sides of
the outer tube 14. The projection 48, in the exemplary embodiment,
is sized to rotate with in the groove provided in the cap 41, thus
allowing the cap 41 to rotate relative to the inner tube 12. The
resilient tabs 46 are radially flexible to facilitate connection to
and removal from the cap 41. One skilled in the art will appreciate
that other configurations for connecting the inner tube 12 to the
cap 41 are possible and are within the scope of the present
disclosure.
[0040] The inner tube 12 may be inhibited from rotating with
respect to the outer tube 14, limiting the relative motion of the
inner tube 12 and the outer tube 14 to along the longitudinal axis
16 of the percutaneous access device. For example, one or more
resilient tabs 56 may be provided on the inner tube 12
approximately midway between the proximal end 20 and the distal end
22 of the inner tube 12, although other positions are possible. In
the illustrated embodiment, two resilient tabs 56 are provided on
opposite sides of the outer tube 14. One or more of the resilient
tabs 56 may include a projection 58 that is sized and shaped to
seat within a longitudinal slot 54 provided in the outer sleeve 14.
The resilient tab 56 can be radially flexible to facilitate
insertion into and removal from the slot 54. The projection 58 can
slide within the slot 54 and, thereby can limit the relative motion
between the inner tube 12 and the outer tube 14 to along the
longitudinal axis 16 of the percutaneous access device 10. One
skilled in the art will appreciate that other configurations for
connecting the inner tube 12 to the outer tube 14 are possible and
are within the scope of the present disclosure.
[0041] The inner tube 12 may have one or more sidewall openings or
slots 60 formed therein. In the illustrated exemplary embodiment,
the inner tube 12 includes two opposed slots 60 that extend
longitudinally from the distal end 22 of the inner tube 12. Like
the inner tube 12, the outer tube 14 may have one or more sidewall
openings or slots 62 formed therein. In the illustrated exemplary
embodiment, the outer tube 14 includes two opposed slots 62 that
extend longitudinally from the distal end 32 of the inner tube 12.
The slots 60 and 62 can be used to facilitate positioning of a
spinal fixation device, such as a rod or a plate, relative to one
or more bone anchors. Methods and devices for spinal fixation
element placement are disclosed in commonly owned, co-pending U.S.
patent application Ser. No. 10/737.537, filed Dec. 16, 2003,
entitled Method and Devices for Spinal Fixation Element Placement
(Attorney Docket No. 101896-210) and commonly owned co-pending U.S.
patent application Ser. No. 10/738,130, filed Dec. 16, 2003,
entitled Method and Devices for Minimally Invasive Spinal Fixation
Element Placement, (Attorney Docket No. 101896-209), both of which
are incorporated herein in by reference. To facilitate positioning
of a spinal fixation element, the slots 60 and the slots 62 are
preferably aligned with one another along at least a portion of the
longitudinal axis of the percutaneous access device 10. The width
and length of the slot 60 and slot 62 may be varied depending on
the particular methods, instruments, and fixation elements being
employed. In one exemplary embodiment, for example, the length of
the slots 60 and 62 is selected to span at least from the skin
incision to the distal end of the inner tube 12 and the outer tube
14, respectively. In such embodiments, the slots 60 and 62 may be
accessible from outside of the patient. In another exemplary
embodiment, the length of the slots 60 and 62 is selected to span
from the distal end of the inner tube 12 and the outer tube 14,
respectively, to a point distal to the skin incision. In such
embodiments, the slots 60 and 62 may be accessible only from the
lumens of the inner and outer tubes.
[0042] In embodiments in which multiple slots are employed, the
slots 60, 62 need not be similarly sized (width and/or length). For
example, the one or more slots 60 may be sized differently than the
one or more slots 62, the one or more of the slots 60 on the inner
tube may be sized differently than other slots 60, and/or one or
more of the slots 62 on the outer tube may be sized differently
than other slots 62. Although the exemplary embodiment includes two
opposing slots on the inner tube 12 and the outer tube 14,
respectively, one skilled in the art will appreciate that any
number of slots may be provided, e.g., no slots, one, two, three,
etc. slots, may be provided depending on the method, instruments,
and/or fixation element employed.
[0043] One skilled in the art will appreciate that the slots 60 and
62 are optional and that in certain embodiments slots may not be
provided.
[0044] Referring to FIGS. 1-5 and 7, the percutaneous access device
10 is preferably releasably engageable to a bone anchor. In the
exemplary embodiment, the outer tube 14 may be releasably engaged
to a bone anchor, such as bone anchor assembly 100. For example,
the outer tube 14 may be engaged to a bone anchor in a manner that
allows the percutaneous access device 10 to be connected to the
bone anchor 100 during use, e.g., during implantation and/or
delivery and/or fastening of a spinal fixation element to the bone
anchor, and allows the percutaneous access device to be
disconnected from the bone anchor 100 at the conclusion of the
procedure. Preferably, the percutaneous access device 10 can be
disconnected remotely. For example, the exemplary embodiment, the
percutaneous access device 10 can be disconnected from the bone
anchor by manipulation of the proximal end of the percutaneous
access device 10, as discussed in more detail below.
[0045] The distal end 32 of the outer tube 14 includes a pair of
opposed longitudinally extending tabs 70A and 70B that may
releaseable engage a bone anchor. In the exemplary embodiment, the
tabs 70A and 70B are defined by the sidewalls of the outer tube 14
and are separated by slots 62A and 62B. In certain exemplary
embodiments, the tabs 70A and 70B may be flexible and resilient in
the radial direction to facilitate connection to a bone anchor. For
example, the tabs 70A and 70B may be flexed apart in the radial
direction from a first, relaxed position to facilitate advancement
of the tabs longitudinally over a portion of the bone anchor. Once
positioned about a portion of the bone anchor, the tabs 70A and 70B
may provide a radially compressive force on the bone anchor as the
tabs 70A and 70B attempt to return to the first, relaxed position.
In other exemplary embodiments, including the exemplary
percutaneous access device 10, the tabs 70A and 70B need not be
flexible and resilient.
[0046] In the illustrated exemplary embodiment, each tab 70A and
70B may include one or more radially inward facing projection 72
that is sized and shaped to seat within an opening provided in a
portion of the bone anchor. The size, shape and number of
projections can be varied depending on, for example, the opening(s)
provided on the bone anchor and type of connection desired. In the
illustrated exemplary embodiment, for example, each projection 72A,
72B is generally arcuate in shape and has a cross section that is
complementary to an arcuate groove 130 provided in the spinal
fixation element receiving member 108 of the exemplary bone anchor
assembly 100 described below. In particular, the projection 72A has
a distal surface 74, a proximal surface 76, and a generally
radially facing connecting surface 78 that spans between the distal
surface 74 and the proximal surface 76, as shown in FIG. 8. In the
illustrated embodiment, the distal surface 74 is generally oriented
perpendicular to the longitudinal axis of the outer tube 14 and the
connecting surface 78 is generally oriented parallel to the
longitudinal axis of the outer tube 14 and perpendicular to the
distal surface 74. One or both of the proximal surface 76 and the
distal surface 74 may be oriented at an angle other than
perpendicular to the longitudinal axis of the outer tube 14. For
example, the proximal surface 76 may be oriented at an angle A to
an orthogonal line 80, which is oriented perpendicular to the
longitudinal axis of the outer tube 14. In the exemplary
embodiment, the angle A may be approximately 5.degree. to
approximately 30.degree. and is preferably approximately
20.degree.. The distal surface 74 and the proximal surface 76 may
be oriented at the same angle or, as in the exemplary embodiment,
may be oriented at different angles.
[0047] Referring to FIGS. 2, 3, 4, 7, 9 and 10, the distal end 22
of the inner tube 12 may include a contact surface 81 that contacts
at least a portion of a bone anchor when the inner tube 12 is in
the second position. In the illustrated exemplary embodiment, for
example, the distal end 22 of the inner tube 12 may have two
opposing generally arcuate contact surfaces 81. The contact
surfaces 81, in the exemplary embodiment, are oriented
approximately perpendicular to the longitudinal axis of the inner
tube 12. In the illustrated exemplary embodiment, the contact
surfaces 81 are configured to contact a generally arcuate contact
surface provided on the proximal end of the receiving member of the
exemplary bone anchor assembly 100. Preferably, the contact surface
81 is complementary in size, shape, and orientation to the contact
surface on the bone anchor. One skilled in the art will appreciate
that the configuration of the contact surface 81, e.g., number,
size, shape, and orientation of the contact surface 81, may be
varied to, for example, suit the bone anchor being employed.
[0048] The distal end 22 of the inner tube 12 and/or the distal end
32 of the outer tube 14 may be configured to inhibit rotation of
the bone anchor assembly relative to the percutaneous access device
10. For example, the distal end 22 of the inner tube may include
one or more finger-like extensions 82 that extend approximately
axially from the distal end 22 of the inner tuber 12 and engage a
bone anchor to inhibit rotation of the bone relative to the
percutaneous access device. For example, one or more of the
extensions 82 may seat within a groove, recess, slot, or similar
structure provided in the bone anchor. Alternatively, one of more
of the extensions 82 may include a contact surface 84 for
contacting an axially extending surface of the bone anchor, as in
the case of the exemplary embodiment and as discussed in detail
below.
[0049] FIGS. 5-6 illustrate an exemplary embodiment of a bone
anchor assembly 100 that is particularly suited for use with the
exemplary percutaneous access device 10 described. One skilled in
the art will appreciate, however, that the percutaneous access
devices disclosed herein are not limited to use with the exemplary
bone anchor assembly 100 but instead may be configured for use with
any type of bone anchor, e.g., bone screw or hook; mono-axial or
polyaxial. Exemplary bone anchor assembly 100 includes a bone screw
102, such as a pedicle screw, having a proximal head 104 and a
distal bone engaging portion 106, which in the illustrated
exemplary embodiment is an externally threaded screw shank. The
exemplary bone screw assembly 100 also includes a receiving member
108 that is configured to receive and couple a spinal fixation
element, such as a spinal rod or spinal plate, to the bone anchor
assembly 100.
[0050] The receiving member 108 may be coupled to the bone anchor
102 in any well-known conventional manner. For example, the bone
anchor assembly may be poly-axial, as in the present exemplary
embodiment in which the bone anchor 102 may be adjustable to
multiple angles relative to the receiving member 108, or the bone
anchor assembly may be mono-axial, e.g., the bone anchor 102 is
fixed relative to the receiving member 108. An exemplary poly-axial
bone screw is described U.S. Pat. No. 5,672,176, incorporated
herein by reference. In mono-axial embodiments, the bone anchor 102
and the receiving member may be coaxial or may be oriented at angle
with respect to one another. In poly-axial embodiments, the bone
anchor may biased to a particular angle or range of angles to
provide a favored angle the bone anchor. Exemplary favored-angle
bone screws are described in U.S. Patent Application Publication
No. 2003/0055426 and U.S. Patent Application Publication No.
2002/0058942, both of which are incorporated herein by
reference.
[0051] The receiving member 108 of the illustrated exemplary
embodiment includes a proximal end 110, a distal end 112, and a
recess or slot 114 for receiving a spinal fixation element such as
a spinal rod. The proximal end 110 of the receiving member 108 has
a first bore 116 defining a first bore axis 118. The recess 114
communicates with the first bore 116 such that a spinal fixation
element may be positioned through the first bore 116 into the
recess 114. The distal end 112 has a second bore 120 opposite the
second bore 116 and defining a second bore axis 122. The second
bore axis 122 is designed to receive the head 104 of the bone
anchor 102 to couple the bone anchor 102 to the receiving member
108. In the illustrated exemplary embodiment, the head 104 is
seated within the second bore 116. As the exemplary illustrated
embodiment of the bone anchor assembly is poly-axial, the bone
anchor 102 is free to rotate relative to the receiving member 108
such that the longitudinal axis 124 of the bone anchor 102 is
positionable at an angle relative to the second bore axis 120. The
second bore 116 may be conically shaped to facilitate adjustment of
the bone anchor 102 relative to the receiving member 108. In
favored-angled embodiments, the second bore axis 122 may be
positioned at an angle (other than 0.degree.) to the first bore
axis 118. In the illustrated embodiment, the first bore axis 118
and second bore axis 122 are coaxial. In the exemplary embodiment,
the receiving member 108 has a generally U-shaped cross-section
defined by two legs 124A and 124B separated by recess 114. Each leg
124A, 124B is free at the proximal end 110 of the receiving member
108.
[0052] The receiving member 108 may be configured to receive a
closure mechanism that locks a spinal fixation element within the
recess 114. The closure mechanism may be a cap that is advanceable
through the first bore 116 of the receiving member 108 and seats
against the spinal fixation element. For example, the cap may have
external threads that engage internal threads 148 provided in the
receiving member 108, e.g., on the legs 124A,B, as in the exemplary
embodiment. Any type of conventional closure mechanism may be
employed, including, for example, non-threaded caps,
multi-component closure mechanisms, and/or external caps.
[0053] The receiving member 108 of the exemplary bone anchor
assembly 100 is configured to be releasably connected to an
instrument such as the exemplary percutaneous access device 10
described above. For example, the receiving member 108 may include
at least one groove 130 that is configured to receive a portion of
an instrument to releasably connect the instrument to the bone
anchor assembly. The size, shape, position, and number of grooves
can be varied depending on, for example, the instrument employed
and the type of connection desired. In certain embodiments, for
example, at least one arcuate groove 130 may be provided on an
exterior surface of the proximal end 110 of the receiving member
108. In other exemplary embodiments, at least one arcuate groove
may be provided on an interior surface of the proximal end 110 of
the receiving member 108. In the illustrated exemplary embodiment,
each leg 124A and 124B may be provided with an arcuate groove 130A,
130B, respectively, at the free, proximal end of the leg 124A,
124B. The grooves 130A, 130B may extend about a portion or all of
the circumference of the proximal end of each leg 124A, 124B. Each
groove 130A, 130B may have size and shape that is complementary in
size and shape to a projection provided on the instrument. For
example, in the illustrated exemplary embodiment, the each groove
130A, 130B may be arcuate and may have a cross-section
complementary to the cross-section of a projection 72A,72B provided
on the tabs 70A,70B of the outer sleeve 14. In particular, groove
130 may have a distal surface 132, a proximal surface 134 and an
interconnecting surface 136 that spans between the distal surface
132 and the proximal surface 134, as illustrated in FIG. 8. The
distal surface 132 and/or the proximal surface 134 may be oriented
to facilitate insertion of a projection into the grove 130 and/or
to inhibit undesirable separation of the projection from the groove
130. In the illustrated exemplary embodiment, for example, the
distal surface 132 may be generally oriented at an angle B to an
orthogonal line 140, which is oriented perpendicular to the
longitudinal axis of the receiving member 108, to facilitate
insertion of the projection into the groove. In the exemplary
embodiment, the angle B may be approximately 0.degree. to
approximately 45.degree. and preferably approximately 30.degree. to
40.degree.. In the illustrated exemplary embodiment, the proximal
surface 134 may be oriented at an angle other than perpendicular to
longitudinal axis of the receiving member 108 to inhibit separation
of the projection from the groove 130, particularly in radial
direction. For example, the proximal surface 134 may be oriented at
an angle C to an orthogonal line 142, which is perpendicular to the
longitudinal axis of the receiving member 108. In the exemplary
embodiment, the angle C may be approximately 5.degree. to
approximately 30.degree. and is preferably approximately
20.degree.. The distal surface 132 and the proximal surface 76 may
be oriented at the same angle or, as in the exemplary embodiment,
may be oriented at different angles. The grooves 130A and 130B, as
well as any additional grooves, may have similar cross-sectional
geometries, as in the case of the illustrated exemplary embodiment,
or may have distinct geometries.
[0054] Referring to FIGS. 7 and 8, the proximal surface 76 of each
projection 72 may be oriented at an angle A that is approximately
equal to the angle C of the proximal surface 134 of the
corresponding groove. In one preferred embodiment, for example,
angle A and angle C are each approximately 20.degree.. One skilled
in the art will appreciate that angle A and angle C need not be
approximately equal but instead, may be separate, distinct
angles.
[0055] The proximal end 110 of the receiving member 108 may include
one or more contact surfaces that may be contacted by an instrument
such as the percutaneous access device 10. In the illustrated
exemplary embodiment, for example, the proximal end of each leg
124A, 124B may include one or more generally arcuate, proximally
facing contact surfaces 145.
[0056] The outer diameter of the percutaneous access device may be
selected to be approximately equal to the outer diameter of the
bone anchor to facilitate insertion of the bone anchor into the
body through a percutaneous pathway of minimal size. For example,
in the illustrated exemplary embodiment, the outer diameter of the
outer tube 14, indicated by line D.sub.1 in FIG. 7, at at least the
distal end 32 of the outer tube 14, is approximately equal to, or
less than, the outer diameter of the receiving member 108,
indicated by line d.sub.1 in FIGS. 6 and 7. For example, the
diameter of the outer tube 14 may taper from a proximal diameter
D.sub.2 to a distal diameter D.sub.1 at the distal end 32 of the
outer tube 14. Alternatively, the outer diameter of the outer tube
14 may be approximately equal to, or less than, the outer diameter
of the receiving member 108 along the entire length of the outer
tube 14. To accommodate the outer tube 14, the proximal end 110 of
the receiving member 108 may have a diameter d.sub.2 that is less
than the diameter d.sub.1 of a distal section of the receiving
member 108, as illustrated in FIG. 6. For example, the diameter
d.sub.2 proximal to the grooves 130A,B may be less than the
diameter d.sub.1 of the receiving member 108 to provide a reduced
diameter portion 150 at he proximal end 130 of the receiving
member. The distance between the exterior surface of reduced
diameter portion 150 and the exterior surface of the receiving
member 108, indicated by line E in FIG. 6 and 8, is preferably
greater than or approximately equal to the radial thickness of a
tab 70A, 70B, as indicated by line F in FIG. 8.
[0057] To facilitate delivery of devices to the bone anchor
assembly through the percutaneous access device 10, the inner
diameter of the lumen 24 of the inner tube 12, indicated by line F
in FIG. 7, at at least the distal end of the inner tube 12, may be
greater than or approximately equal to the inner diameter of at
least a portion of the receiving member, indicated by line f in
FIG. 7.
[0058] Exemplary operation of the percutaneous access device 10
with the exemplary bone anchor assembly will be described with
reference to FIGS. 11A-11D. To releasably connect the percutaneous
access device 10, the distal end 32 of the outer tube 14 is
oriented such that tabs 70A and 70B are aligned with recess 114, as
illustrated in FIG. 11A. The percutaneous access device 10 is
advanced distally until each tab 70A, 70B is positioned between the
legs 124A and 124B, as illustrated in FIG. 11B. The percutaneous
access device 10 may be rotated about its longitudinal axis 16 to
rotate projections 72A, 72B into grooves 103B, 130A, respectively,
as illustrated in FIG. 11C. The inner tube 12 may be advanced
distally along the longitudinal axis 16 of the percutaneous access
device 10 from the first, proximal position, illustrated in FIGS.
11A-C, to the second, distal position, illustrated in FIG. 11D, in
which the contact surfaces 81 of the inner tube 12 contact the
contact surfaces 145A, 145B provided on the proximal end of the
receiving member of the exemplary bone anchor assembly 100, to
thereby releasably connect the percutaneous access device 10 to the
bone anchor assembly 100. The contact surface 84 of one or more of
the extensions 82 may engage the axial extending contact surfaces
152 (FIGS. 5 and 6) to inhibit rotation between the percutaneous
access device and the bone anchor assembly.
[0059] The percutaneous access device 10 may be connected to the
exemplary bone anchor assembly 100, or another bone anchor
assembly, before implantation of the bone anchor assembly or after
the bone anchor assembly is implanted into the patient's body.
[0060] Once the percutaneous access device 10 is releasably
connected to the bone anchor assembly 100 as illustrated in FIGS. 1
and 11D, the percutaneous access device 10 may provide a
percutaneous pathway between the skin incision and the bone anchor
100 that facilitates delivery of instruments, spinal fixation
elements, and/or components of the bone anchor assembly, such as
the closure mechanism, to the bone anchor assembly 100. In the
illustrated exemplary embodiment, for example, the lumen 24
provides a pathway to the first bore 116 of the receiving member
108 of the bone anchor assembly 100, that may allow a closure
mechanism, such as a threaded cap, to be delivered to the receiving
member 108 of the bone anchor assembly and/or may allow a screw
driver or the like to be advanced into engagement with the head 104
of the bone anchor 102. Moreover, in the illustrated exemplary
embodiment, the slots 60 of the inner tube and the slots 62 of the
outer tube 14 may be aligned with the recess 114 provided in the
receiving member 108. Alignment of the slots 60 and 62 with the
recess 114 facilitates the delivery of a spinal fixation element to
the bone anchor assembly. Exemplary methods and devices for
delivering a spinal fixation element to a bone anchor assembly are
described in commonly owned, co-pending U.S. patent application
Ser. No. 10/737,537, filed Dec. 16, 2003, entitled Method and
Devices for Spinal Fixation Element Placement (Attorney Docket No.
101896-210) and commonly owned co-pending U.S. patent application
Ser. No. 10/738,130, filed Dec. 16, 2003, entitled Method and
Devices for Minimally Invasive Spinal Fixation Element Placement,
(Attorney Docket No. 101896-209), each of which is incorporated
herein in by reference.
[0061] The percutaneous access device 10 may be released from the
bone anchor by rotating the percutaneous access device 10 about its
longitudinal axis 16 and retracting the device 10 distally.
[0062] FIGS. 12-16 illustrate an alternative exemplary embodiment
of a bone anchor assembly 200 and an exemplary percutaneous access
device 300 that may be configured to releasably engage the bone
anchor assembly 200. The exemplary bone anchor assembly 200 is
analogous in construction to the exemplary bone anchor assembly 10
described above, except that the receiving member 208 of the bone
anchor assembly 200 has a generally constant outer diameter
d.sub.1, as illustrated in FIGS. 14 and 16, at the proximal end 110
thereof, and, thus, lacks the reduced diameter portion 150 of bone
anchor assembly 100. As a result, the outer diameter of the distal
end 32 of the outer tube 14 of the exemplary percutaneous access
device 300, indicated by line D.sub.2 in FIG. 16, may be
approximately equal to or, as in the illustrated embodiment, may be
greater than the diameter d.sub.1 of the proximal end 110 of the
receiving member 208. The outer diameter of the outer tube 14 may
be constant, as in the illustrated exemplary embodiment, or may
vary along the length of the outer tube 14.
[0063] FIGS. 17A and 17B illustrate an alternative embodiment of a
percutaneous access device 350 and a bone anchor assembly 400, in
which the percutaneous access device and the bone anchor assembly
are interconnected by threads. For example, the percutaneous access
device 350 may have an outer tube 352 having a distal end 354
provided within internal threads that releasably engage external
threads 406 provided on the proximal end 412 of the receiving
member 408 of the bone anchor assembly 400. Preferably, the
external threads 406 are clocked to facilitate alignment of the
grooves 62, if any, provided on the outer tube 14 with the recess
414 provided in the receiving member 408. In the illustrated
exemplary embodiment, the percutaneous access device 350 includes a
single tube, outer tube 352; an inner tube may be provided but is
not necessary.
[0064] FIGS. 18A and 18B illustrate an alternative embodiment a
bone anchor assembly 500, in which the receiving member 508
includes one or more removable, externally threaded tabs 502 that
provide a threaded connecting between the percutaneous access
device 350 and the bone anchor assembly 500. In the illustrated
exemplary embodiment, a pair of proximally extending tabs 502A and
502B extend from the legs 524A and 524B, respectively. Each tab
502, in the illustrated exemplary embodiment, is generally arcuate
in shape and includes external threads for engagement with internal
threads provided on the percutaneous access device. The tabs 502
may include internal threads 415 to facilitate advancement of a
closure mechanism to the bone anchor assembly. Tabs 502 may be
sheared off the bone anchor assembly 500 by over tightening of the
percutaneous access device 350 or, alternatively, may be removed
from the bone anchor assembly 500 after withdrawal of the
percutaneous access device 350 by a suitable instrument.
[0065] FIGS. 19A-19D illustrate an alternative embodiment of a
percutaneous access device 550 and a bone anchor assembly 600, in
which the percutaneous access device 500 and the bone anchor
assembly 600 are releasably interconnected by one or more internal
wires 551. In the illustrated exemplary embodiment, for example, a
pair of wires 551, extend axially through opposing side walls of
the outer tube 552. Each wire extends through parallel axial holes
provided in the side walls of the outer tube 552. Each wire 551 may
form a loop 553 that can engage the receiving member 608 of the
bone anchor assembly. The wires may be formed of any suitable
biocompatible material including, for example a metal, such as a
stainless, or a polymer. The receiving member 608, in the exemplary
embodiment, includes two pairs of axially extending holes 611 for
receiving wires 551. Each pair of holes 611 may terminate in a
groove 613 oriented perpendicular to the holes 611. The number of
wires and holes provided in the outer tube and the receiving member
may be varied depending on the application. Each wire 551 may be
tensioned to couple the percutaneous access device 550 to the bone
anchor assembly. The wires 551 may be tensioned by, for example,
retracting the wires 551 distally. Releasing the tension on the
wires 551 by, for example, cutting the wires 551 or advancing the
wires 551 proximally, can release the percutaneous access device
550 from the bone anchor assembly 600. In the illustrated exemplary
embodiment, the percutaneous access device 550 includes a single
tube, outer tube 552; an inner tube may be provided but is not
necessary.
[0066] FIGS. 20A-20D illustrates an alternative embodiment of a
percutaneous access device 650 and a bone anchor assembly 700 in
which the percutaneous access device 650 and the bone anchor
assembly 700 are releasably interconnected by one or more
externally positioned wires 551. The illustrated exemplary
embodiment, wires 551 extend axially along the exterior surface of
the outer tube 652 of the percutaneous access device 650 and extend
axially along the exterior surface of the receiving member 708 of
the bone anchor assembly 700. The outer tube 652 may include one or
more axially oriented grooves 653 in which the wires 551 may be
seated. Likewise, the receiving member 708 may include one or more
grooves 707 in which the wires 651 may be seated. The number of
wires and/or grooves may be varied depending upon the particular
application. In the illustrated embodiment, for example, a pair of
parallel grooves 653 are provided in opposing sidewalls of the
outer tube 652 and a pair of parallel of grooves 707 are provided
in the opposing legs 724A, 724B of the receiving member 708. Each
wire 551 may be tensioned to couple the percutaneous access device
650 to the bone anchor assembly 700. The wires 551 may be tensioned
by, for example, retracting the wires 551 distally. Releasing the
tension on the wires 551 by, for example, cutting the wires 551 or
advancing the wires 551 proximally, can release the percutaneous
access device 650 from the bone anchor assembly 700. In the
illustrated exemplary embodiment, the percutaneous access device
650 includes a single tube, outer tube 652; an inner tube may be
provided but is not necessary.
[0067] FIG. 21 illustrates an alternative embodiment of a bone
anchor assembly 800 having one or more removable tabs 801 for
releasable engagement with an instrument such as an embodiment of a
percutaneous access device described above. In the illustrated
exemplary embodiment, a pair of opposing tabs 801A, 801B extend
proximally from the proximal end of the receiving member 808 of the
bone anchor assembly 800. Each tab 801A, 801B, in the illustrated
exemplary embodiment, is generally arcuate in shape and are
positioned proximal to and extend from a respective leg 824A, 824B
of the receiving member 808. The size, shape, and number of tabs
801 may be varied without departing from the scope of the present
invention. The tabs 801 may include a mechanism for facilitating
releasable engagement by an instrument. For example, the tabs may
be provided with external threads, as in the case of the embodiment
illustrated in FIGS. 17A, 17B described above, or may include one
or more grooves. In the illustrated exemplary embodiment, each tab
801A, 801B includes one or more arcuate grooves 830A, 830B that may
be analogous in construction to the grooves 130A, 130B described
above. The tabs 801 may include internal threads 815 to facilitate
advancement of a closure mechanism to the bone anchor assembly.
Tabs 801 may be sheared off the bone anchor assembly 800 by the
percutaneous access device or instrument or, alternatively, may be
removed from the bone anchor assembly 800 after withdrawal of the
percutaneous access device or instrument using a suitable
instrument.
[0068] FIGS. 22A-22B illustrates an exemplary embodiment of a
percutaneous access device 850 having one or more axially extending
cut-outs 853 provided in the outer tube 852 of the percutaneous
access device. As illustrated in FIG. 22B, an axially extending
cut-out 853 may facilitate the use of multiple percutaneous access
devices by minimizing interference between the devices. For
example, in certain spinal applications, bone anchors placed on
adjacent vertebrae may be closely spaced and/or angled in a manner
that may cause interference between instruments, such as a
percutaneous access device disclosed herein, used simultaneously
with the adjacent bone anchors. By providing axial cut-outs 853,
two or more percutaneous access devices 850A, 850B may be employed
on adjacent bone anchors, or closely positioned anchors, by
aligning the cut-outs 853A, 853B. The length and depth of a cut-out
852 may be varied depending on the application. One or more
cut-outs may be provided on any of the exemplary embodiments of the
percutaneous access device described herein or with other
instruments used with bone anchors, e.g., drills, drivers,
cannulas, approximators, and the like. In embodiments including an
inner tube or additional tubes, the additional tubes may also be
provided with cut-outs 853.
[0069] FIGS. 23A-23B illustrates an alternative embodiment of a
percutaneous access device 950 and a bone anchor assembly 900 in
which the distal end 956 of the inner tube 954 of the percutaneous
access device 950 includes one or more flexible bone anchor
engaging tabs 958 for releasable engagement with the receiving
member 908 of bone anchor assembly 900. In the exemplary
embodiment, a pair of opposing tabs 958A, 958B extend distally from
the distal end 956 of the inner tube 954. Each tab 958, in the
illustrated exemplary embodiment, is connected at a proximal end to
the inner tube 954 and has a free distal end 960. One or both of
the tabs 958 can flex from a first position, in which the tab 958
is oriented approximately axially, e.g., parallel to the
longitudinal axis of the inner tube 954, to a second position, in
which the tab 958 is generally oriented at angle to the
longitudinal axis of the inner tube 954. In the exemplary
embodiment, for example, each tab 958A, 958B may flexed radially
outward, e.g., away from each other, from a first position, in
which the tabs 958A, 958B are approximately parallel, to a second,
flexed positioned, in which the tabs 958A, 958B are oriented at an
angle to one another. The tabs 958 may be biased to the first
position. For example, the tabs 958A, 958B may be biased to the
first, parallel position, such that the tabs 958A, 958B may provide
a radially compressive force on the receiving member 908 to
releasably engage the receiving member 908. One or more of the tabs
958 may be provided with a projection or the like for engaging a
hole, groove, etc, that may be provided in the exterior surface of
the receiving member 908. Although the exemplary embodiment
includes two tabs 958A, 958B, any number (one or more) tabs 958 may
be provided.
[0070] The percutaneous access device 950 may include an outer tube
952 that may be advanced about the tabs 958 when the tabs 958
releasably engage the receiving member 908. For example, in the
illustrated exemplary embodiment, the outer tube 952 may be
advanced distally about the tabs 958A, 958B when the tabs are in
the second, flexed position, to inhibit separation of the tabs
958A, 958B and/or provide a radially compressive force on the
tabs.
[0071] Non-limiting examples of applications of the bone fixation
plates described herein include long bone fracture
fixation/stabilization, small bone stabilization, lumbar spine as
well as thoracic stabilization/fusion, cervical spine
compression/fixation, and skull fracture/reconstruction
plating.
[0072] While the percutaneous access systems and bone anchor
assemblies of the present invention have been particularly shown
and described with reference to the exemplary embodiments thereof,
those of ordinary skill in the art will understand that various
changes may be made in the form and details herein without
departing from the spirit and scope of the present invention. Those
of ordinary skill in the art will recognize or be able to ascertain
many equivalents to the exemplary embodiments described
specifically herein by using no more than routine experimentation.
Such equivalents are intended to be encompassed by the scope of the
present invention and the appended claims.
* * * * *