U.S. patent application number 11/828684 was filed with the patent office on 2009-01-29 for spinal rod reduction instruments and methods for use.
This patent application is currently assigned to DEPUY SPINE, INC.. Invention is credited to Richard W. Fournier, Thomas J. Gamache, Thomas J. Runco.
Application Number | 20090030420 11/828684 |
Document ID | / |
Family ID | 40282066 |
Filed Date | 2009-01-29 |
United States Patent
Application |
20090030420 |
Kind Code |
A1 |
Runco; Thomas J. ; et
al. |
January 29, 2009 |
SPINAL ROD REDUCTION INSTRUMENTS AND METHODS FOR USE
Abstract
Methods and devices are provided for reducing a spinal fixation
element into a spinal implant element. In one exemplary embodiment,
a spinal rod reduction device is provided for reducing a spinal
fixation element into a spinal implant element. The spinal rod
reduction device can include a fastener engaging member for
engaging at least a portion a spinal implant element, a reduction
member for engaging at least a portion of a spinal fixation
element, and a handle assembly mated to the reduction member. The
handle assembly can be designed in such a way that actuation of the
handle assembly causes movement of the reduction member relative to
the fastener engaging member and the movement of the reduction
member reduces the spinal fixation element into the spinal implant
element. Two different styles of spinal rod reduction devices are
discussed in detail. Various techniques are also provided for
reducing a spinal fixation element into a spinal implant
element.
Inventors: |
Runco; Thomas J.; (Canton,
MA) ; Fournier; Richard W.; (New Bedford, MA)
; Gamache; Thomas J.; (Westport, MA) |
Correspondence
Address: |
NUTTER MCCLENNEN & FISH LLP
WORLD TRADE CENTER WEST, 155 SEAPORT BOULEVARD
BOSTON
MA
02210-2604
US
|
Assignee: |
DEPUY SPINE, INC.
Raynham
MA
|
Family ID: |
40282066 |
Appl. No.: |
11/828684 |
Filed: |
July 26, 2007 |
Current U.S.
Class: |
606/99 ;
606/207 |
Current CPC
Class: |
A61B 17/7086
20130101 |
Class at
Publication: |
606/99 ;
606/207 |
International
Class: |
A61B 17/58 20060101
A61B017/58; A61B 17/00 20060101 A61B017/00 |
Claims
1. A spinal rod reduction device, comprising: a fastener engaging
member having first and second jaws adapted to engage at least a
portion of a fastener; a housing fixedly coupled to the fastener
engaging member; a pusher member at least partially disposed inside
the housing; a reduction member coupled to a distal end of the
pusher member; and a handle assembly coupled to a proximal end of
the pusher member and adapted to move the pusher member parallel to
a longitudinal axis of the fastener engaging member to cause the
reduction member to reduce a spinal rod extending between the first
and second jaws into a fastener engaged by the first and second
jaws.
2. The device of claim 1, wherein the handle assembly comprises an
actuator pivotally coupled to a handle formed on a proximal end of
the housing.
3. The device of claim 2, further comprising a biasing element
disposed between the actuator and the handle and adapted to bias
the actuator to one of an open and closed position.
4. The device of claim 3, wherein the biasing element comprises a
leaf spring.
5. The device of claim 1, wherein the reduction member comprises a
sleeve disposed around the first and second jaws and adapted to
lock the first and second jaws in a fixed position relative to one
another as a spinal rod is reduced into a fastener engaged by the
first and second jaws.
6. The device of claim 1, wherein the housing is offset from and
extends substantially parallel to the longitudinal axis of the
fastener engaging member.
7. The device of claim 1, further comprising a locking mechanism
coupled to the handle assembly and adapted to maintain the
reduction member in a desired fixed position relative to the first
and second jaws.
8. The device of claim 7, wherein the locking mechanism comprises
at least one notch formed in the pusher member, and at least one
protrusion located on the handle assembly and adapted to engage the
at least one notch.
9. The device of claim 1, further comprising a locking mechanism
coupled to the housing and adapted to selectively engage the pusher
member to maintain the pusher in a desired fixed position relative
to the housing.
10. The device of claim 1, wherein the first and second jaws are
spaced a distance apart to define an opening therebetween.
11. A spinal rod reduction device, comprising: a hollow elongate
member having a distal end with opposed arms adapted to engage a
fastener therebetween; a housing coupled to the hollow elongate
member; and a pusher slidably disposed through the housing and
having a reduction member formed on a distal end thereof and
disposed around the hollow elongate member, the reduction member
being adapted to reduce a spinal rod extending between the opposed
arms into a fastener engaged by the opposed arms as the pusher is
slidably advanced relative to the housing.
12. The device of claim 11, further comprising a handle assembly
coupled to the housing and the pusher and adapted to move the
pusher relative to the housing.
13. The device of claim 12, wherein the handle assembly comprises a
first handle coupled to the housing and a second handle coupled to
the pusher, the first and second handles being pivotally coupled to
one another.
14. The device of claim 12, wherein the handle assembly extends
transverse to a longitudinal axis of the housing and the
pusher.
15. The device of claim 12, further comprising a locking mechanism
coupled to the handle assembly and adapted to maintain the
reduction member in a desired fixed position relative to the first
and second jaws.
16. The device of claim 15, wherein the locking mechanism is
adjustable to allow the first and second arms to be maintained at a
desired fixed position relative to one another.
17. The device of claim 11, wherein the housing is coupled to an
outer sidewall of the hollow elongate member.
18. A method for reducing a spinal rod into a bone anchor,
comprising: positioning a fastener between first and second jaws
formed on a fastener engaging member; and advancing a pusher member
through a housing coupled to the fastener engaging member to
advance a reduction member coupled to a distal end of the pusher
member toward the fastener to reduce a spinal rod extending between
the opposed jaws into the fastener.
19. The method of claim 18, wherein the reduction member is
disposed around the first and second jaws such that the reduction
member locks the jaws in a fixed position as the reduction member
is advanced toward the fastener.
20. The method of claim 18, wherein the pusher member is advanced
by pivoting an actuator coupled to the pusher member toward a
handle coupled to the housing.
21. The method of claim 20, wherein the actuator is maintained in a
desired fixed position by a locking mechanism that extends between
the actuator and the handle.
22. The method of claim 18, further comprising delivering a rod
retainer through a pathway formed in the fastener engaging member,
and applying the rod retainer to the fastener to lock the spinal
rod in the fastener.
23. The method of claim 18, wherein the fastener comprises a bone
screw that is disposed in a vertebra.
24. The method of claim 18, wherein the fastener engaging member is
moved to an open position in order to position the fastener between
the first and second jaws.
Description
FIELD
[0001] Devices and methods are provided for use in spinal surgery,
and in particular spinal rod reduction devices and methods for
using the same are provided.
BACKGROUND
[0002] 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, that is coupled to
adjacent vertebrae by attaching the element to various anchoring
devices, such as hooks, bolts, wires, or screws. The fixation rods
can have a predetermined contour that has been designed according
to the properties of the target implantation site, and once
installed, the instrument 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 devices can be anchored to specific portions
of the vertebra. 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 slot formed in the head. A set-screw, plug, or similar
type of fastening mechanism, is used to lock the fixation 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 fixation rod is seated through the
rod-receiving member of each screw and the rod is locked in place
by tightening a cap or other fastener mechanism to securely
interconnect each screw and the fixation rod.
[0004] While current spinal fixation systems have proven effective,
difficulties have been encountered in mounting rods into the
rod-receiving member of various fixation devices. In particular, it
can be difficult to align and seat the rod into the rod receiving
portion of adjacent fixation devices due to the positioning and
rigidity of the vertebra into which the fixation device is mounted.
Thus, the use of a spinal rod reduction device, also sometimes
referred to as a spinal rod approximator, is often required in
order to grasp the head of the fixation device and reduce the rod
into the rod-receiving head of the fixation device.
[0005] While several rod reduction devices are known in the art,
some tend to be difficult and very time-consuming to use.
Accordingly, there is a need for improved rod reduction devices and
methods for seating a spinal rod, or other spinal fixation element,
into one or more spinal implants or fasteners.
SUMMARY
[0006] Methods and devices are provided for reducing a spinal
fixation element into a fastener to allow the spinal fixation
element to be locked in the fastener. In one embodiment, a spinal
rod reduction device is provided and includes a fastener engaging
member having first and second jaws adapted to engage at least a
portion of a fastener. In an exemplary embodiment, the first and
second jaws are spaced a distance apart from one another to define
an opening therebetween. The first and second jaws can also include
a mating element formed thereon and adapted to engage a fastener.
The device can further include a first arm fixedly coupled to the
fastener engaging member, and a second arm pivotally coupled to the
first arm. A linkage can be pivotally coupled to the second arm and
in an exemplary embodiment the linkage extends transverse to a
longitudinal axis of the fastener engaging member. The device can
also include a reduction member pivotally coupled to the linkage
such that pivotal movement of the second arm relative to the first
arm is effective to move the reduction member along the
longitudinal axis of the fastener engaging member to reduce a
spinal rod extending between the first and second jaws into a
fastener engaged by the first and second jaws. In one embodiment,
the reduction member can include a sleeve disposed around the first
and second jaws and adapted to lock the first and second jaws in a
fixed position. In another embodiment, the reduction member can
include first and second legs having rod-receiving recesses formed
in a distal-most end thereof. In an exemplary embodiment, the
second arm can be movable between an initial position in which the
reduction member is positioned proximal of a distal end of the
first and second jaws, and a final position in which the reduction
member is positioned adjacent to the distal end of the first and
second jaws. The linkage can be adapted to be substantially aligned
with the longitudinal axis of the fastener engaging member when the
second arm is in the final position.
[0007] The device can also have a variety of other configurations.
For example, the first arm can include a proximal portion that
extends substantially parallel to the longitudinal axis of the
fastener engaging member, and a distal portion that extends
transverse to the proximal portion and that is mated to the
fastener engaging member. The device can also include a linear
pathway that extends through the fastener engaging member, the
first arm, and the second arm for receiving a rod retainer for
mating to a fastener engaged by the fastener engaging member.
[0008] In yet another embodiment, the device can include a locking
mechanism coupled to at least one of the first and second arms and
effective to maintain the first and second arms in a desired fixed
position relative to one another. For example, the locking
mechanism can be in the form of at least one notch located on one
of the first and second arms and at least one protrusion located on
the other one of the first and second arms and adapted to engage
the at least one notch. The locking mechanism can also be
adjustable to allow the first and second arms to be maintained at a
desired fixed position relative to one another.
[0009] In another embodiment, a spinal rod reduction device is
provided and includes a hollow elongate member having a handle
formed on a proximal end thereof and extending substantially
parallel to a longitudinal axis of the hollow elongate member, and
first and second jaws formed on a distal end thereof and adapted to
move apart to engage a fastener therebetween. A reduction member is
slidably coupled to the hollow elongate member and it is adapted to
distally advance a spinal rod extending between the first and
second jaws into the fastener engaged by the first and second jaws.
The device can also include a linkage assembly pivotally coupled to
the handle and the reduction member and adapted to advance the
reduction member relative to the first and second jaws. In one
embodiment, the reduction member can include a sleeve disposed
around the hollow elongate member. The sleeve can be movable
between an initial position in which the first and second jaws are
free to flex relative to one another to receive a fastener
therebetween, and a final position in which the first and second
jaws are locked in a fixed position relative to one another to
engage a fastener therebetween.
[0010] While the linkage assembly can have a variety of
configurations, in an exemplary embodiment at least a portion of
the linkage assembly extends transverse to the longitudinal axis of
the hollow elongate member in a first position, and it extends
substantially parallel to the longitudinal axis of the hollow
elongate member in a second position. The linkage assembly can
include, for example, an actuator pivotally coupled to the handle
and at least one linkage extending between the actuator and the
reduction member. The device can also optionally include a locking
mechanism coupled to the handle and effective to maintain the
reduction member in a desired fixed position relative to the hollow
elongate member.
[0011] In other aspects, a method for reducing a spinal rod into a
bone anchor is provided and includes positioning a fastener between
first and second jaws formed on a fastener engaging member, and
pivoting a movable arm toward a stationary arm fixedly mated to the
fastener engaging member to pivot a linkage coupled to the movable
arm from a first position in which the linkage extends transverse
to a longitudinal axis of the fastener engaging member, to a second
position in which the linkage extends substantially parallel to the
longitudinal axis of the fastener engaging member. The linkage can
advance a reduction member toward the fastener as the linkage moves
from the first position to the second position to advance a spinal
rod extending between the opposed jaws into the fastener. The
method can also include delivering a rod retainer through a pathway
extending through the fastener engaging member, and applying the
rod retainer to the fastener to lock the spinal rod in the
fastener. In an exemplary embodiment, the pathway is a linear
pathway extending between the movable arm and the stationary arm
and extending through the fastener engaging member.
[0012] In another embodiment, when the movable arm is pivoted
toward the stationary arm, the reduction member can be advanced
over the first and second jaws into a locked position to lock the
first and second jaws in a fixed position relative to one another
to thereby engage the fastener between the first and second jaws.
The movable arm can also be maintained in the second position by a
locking mechanism that extends between the movable arm and the
stationary arm.
[0013] In yet another embodiment, a spinal rod reduction device is
provided and includes a fastener engaging member having first and
second jaws adapted to engage at least a portion of a fastener, and
a housing fixedly coupled to the fastener engaging member. In an
exemplary embodiment, the housing is offset from and extends
substantially parallel to the longitudinal axis of the fastener
engaging member. The device can also include a reduction member
coupled to a distal end of a pusher member, and a handle assembly
coupled to a proximal end of the pusher member and adapted to move
the pusher member parallel to a longitudinal axis of the fastener
engaging member to cause the reduction member to reduce a spinal
rod extending between the first and second jaws into a fastener
engaged by the first and second jaws. In one embodiment, the handle
assembly can be an actuator pivotally coupled to a handle formed on
a proximal end of the housing. A biasing element can optionally be
disposed between the actuator and the handle for biasing the
actuator to one of an open and closed position. The biasing element
can be, for example, a leaf spring. The device can also include a
locking mechanism coupled to the handle assembly and adapted to
maintain the reduction member in a desired fixed position relative
to the first and second jaws. The locking mechanism can be, for
example, at least one notch formed in the pusher member, and at
least one protrusion located on the handle assembly and adapted to
engage the at least one notch. In another embodiment, a locking
mechanism can be coupled to the housing and it can be adapted to
selectively engage the pusher member to maintain the pusher in a
desired fixed position relative to the housing.
[0014] In yet another embodiment, a spinal rod reduction device is
provided and includes a hollow elongate member having a distal end
with opposed arms adapted to engage a fastener therebetween, a
housing coupled to the hollow elongate member, and a pusher
slidably disposed through the housing and having a reduction member
formed on a distal end thereof and disposed around the hollow
elongate member. The reduction member can be adapted to reduce a
spinal rod extending between the opposed arms into a fastener
engaged by the opposed arms as the pusher is slidably advanced
relative to the housing. The device can further include a handle
assembly coupled to the housing and the pusher and adapted to move
the pusher relative to the housing. The handle assembly can be, for
example, a first handle coupled to the housing and a second handle
coupled to the pusher. The first and second handles can be
pivotally coupled to one another. In one exemplary embodiment, the
handle assembly can extend transverse to a longitudinal axis of the
housing and the pusher. In another embodiment, the housing can be
coupled to an outer sidewall of the hollow elongate member.
[0015] In other aspects, a method for reducing a spinal rod into a
bone anchor is provided and includes positioning a fastener, such
as a bone screw implanted in a vertebra, between first and second
jaws formed on a fastener engaging member. A pusher member can be
advanced through a housing coupled to the fastener engaging member
to advance a reduction member coupled to a distal end of the pusher
member toward the fastener to reduce a spinal rod extending between
the opposed jaws into the fastener. The reduction member can be
disposed around the first and second jaws such that the reduction
member locks the jaws in a fixed position as the reduction member
is advanced toward the fastener. In an exemplary embodiment, the
pusher member is advanced by pivoting an actuator coupled to the
pusher member toward a handle coupled to the housing. The actuator
can optionally be maintained in a desired fixed position by a
locking mechanism that extends between the actuator and the handle.
In other aspects, the method can also include delivering a rod
retainer through a pathway formed in the fastener engaging member,
and applying the rod retainer to the fastener to lock the spinal
rod in the fastener.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The exemplary embodiments disclosed herein will be more
fully understood from the following detailed description taken in
conjunction with the accompanying drawings, in which:
[0017] FIG. 1 is a side perspective view of one exemplary
embodiment of a spinal rod reduction device in an initial
position;
[0018] FIG. 2 is a side perspective view of the device of FIG. 1 in
a final position;
[0019] FIG. 3 is a side perspective view of a fastener engaging
member of the device of FIG. 1;
[0020] FIG. 4 is a partial enlarged side perspective view of the
device of FIG. 1, illustrating a fastener engaging member, a
reduction member, and a linkage;
[0021] FIG. 5 is a top perspective view of the device of FIG.
1;
[0022] FIG. 6 is a side perspective view of another exemplary
embodiment of a spinal rod reduction device in an initial
position;
[0023] FIG. 7 is a side perspective view of the device of FIG. 6 in
a final position;
[0024] FIG. 8 is a partial side perspective view of one embodiment
of a locking mechanism for use with a spinal rod reduction
device;
[0025] FIG. 9 is a partially transparent side view of another
embodiment of a locking mechanism for use with a spinal rod
reduction device;
[0026] FIG. 10 is a partially transparent side view of yet another
embodiment of a locking mechanism for use with a spinal rod
reduction device;
[0027] FIG. 11A is a partially transparent side view of another
locking mechanism for use with a spinal rod reduction device
according to another embodiment;
[0028] FIG. 11B is a front partially transparent view of the
locking mechanism of FIG. 11A;
[0029] FIG. 11C is a side view of a notch on a pusher member that
is part of the locking mechanism of FIGS. 11A and 11B;
[0030] FIG. 11D is a partially transparent perspective side view of
an extension that is part of the locking mechanism of FIGS. 11A and
11B; and
[0031] FIG. 12 is a perspective view of yet another embodiment of a
spinal rod reduction device.
DETAILED DESCRIPTION
[0032] Certain exemplary embodiments will now be described to
provide an overall understanding of the principles of the
structure, function, manufacture, and use of the devices and
methods disclosed herein. One or more examples of these embodiments
are illustrated in the accompanying drawings. Those skilled in the
art will understand that the devices and methods specifically
described herein and illustrated in the accompanying drawings are
non-limiting exemplary embodiments and that the scope of the
present devices and methods is defined solely by 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 devices and methods.
[0033] Methods and devices are provided for reducing a spinal
fixation element, such as a spinal rod, into a fastener, such as a
bone screw. The reduction device can have a variety of
configurations, but in general the device is preferably effective
to manipulate a spinal fixation element into a fastener to allow
the fixation element to be mated to and locked into the fastener.
In one exemplary embodiment, the device can include a fastener
engaging member that is adapted to engage at least a portion of a
fastener, a reduction member that is movably coupled to the
fastener engaging member, and a handle assembly coupled to the
reduction member and that is effective to cause the reduction
member to reduce a spinal fixation element into the fastener.
[0034] A person skilled in the art will appreciate that, although
the spinal rod reduction methods and devices disclosed herein are
described as being used in the spinal area of the body, the methods
and devices can be used in any situation requiring the reduction of
one element into another element, whether it be located in the
spinal area of the body, somewhere else in the body, or otherwise.
A person skilled in the art will also appreciate that the spinal
rod reduction methods and devices can have a variety of
configurations to allow for use in conjunction with
minimally-invasive techniques or conventional surgical procedures.
Furthermore, with particular reference to use in the spinal or
vertebral area of the body, although the description provided
herein describes the spinal fixation element as a spinal rod and
the fastener as a bone screw, a person skilled in the art will
appreciate that the spinal fixation element and the fastener are
not limited to the illustrated embodiments and that the device can
be used with a variety of spinal fixation elements, spinal
implants, fasteners, and other surgical devices.
[0035] FIGS. 1 and 2 illustrate one exemplary embodiment of a
spinal rod reduction device 10. As shown, the device 10 generally
includes a fastener engaging member 20 adapted to engage at least a
portion of a fastener, a reduction member 40 movably coupled to the
fastener engaging member 20, and a handle assembly 60 mated to the
reduction member 40 and adapted to move the reduction member 40
relative to the fastener engaging member 20 to reduce a spinal
fixation element into a fastener engaged by the fastener engaging
member 20.
[0036] As explained above, various fasteners and spinal fixation
elements known in the art can be used, however FIGS. 1 and 2
illustrate one exemplary embodiment of a fastener and a spinal
fixation element that can be used with the rod reduction devices
disclosed herein. As shown, the fastener is in the form of a bone
screw 100 having a threaded shank 102 and a rod-receiving head 104.
The threaded shank 102 can be adapted to be threaded into bone and
the rod-receiving head 104 can be adapted to receive a spinal
fixation element, such as a spinal rod 108. In the illustrated
embodiment, the rod-receiving head 104 includes opposed arms that
define a u-shaped receiving portion for seating the spinal rod 108.
The rod-receiving head 104 can also include mating features formed
thereon to facilitate mating with the fastener engaging member 20.
While various mating features can be used, in one exemplary
embodiment the rod-receiving head 104 includes one or more detents
formed in a proximal portion thereof for receiving one or more
projections formed on the fastener engaging member 20, as will be
discussed in more detail below. Other exemplary mating elements
include, by way of non-limiting example, grooves, threads, etc.
Again, a person skilled in the art will appreciate that other
fasteners can be used including, for example, hooks, plates,
staples, etc.
[0037] The fastener engaging member 20 of the device 10, which is
shown in more detail in FIG. 3, can have a variety of
configurations but it is preferably adapted to engage at least a
portion of a fastener. For example, as shown in FIG. 3, the
fastener engaging member 20 can have an elongate substantially
cylindrical shape and a pathway 22 extending therethrough. The
pathway 22 can serve a number of purposes, but at least two of the
advantages provided are that it can be adapted to receive a rod
retainer for mating to a fastener engaged by the fastener engaging
member 20 and that it can provide access for various instruments to
be used in order to communicate with either the rod retainer or the
fastener. A person skilled in the art will appreciate that the
pathway extending through the fastener engaging member 20 can have
any number of sidewall openings and its cross-section does not need
to form a complete or continuous closed structure, such as an
uninterrupted circle, at any point along the length of the fastener
engaging member. A distal end of the fastener engaging member 20
can be adapted to mate to a fastener, such as bone screw 100. In
the illustrated embodiment the fastener engaging member 20 includes
first and second opposed jaws 24, 26 that extend generally parallel
to one another. The jaws 24, 26 can be spaced a distance apart from
one another, and they can be movably coupled to one another to
allow the jaws 24, 26 to be removably disposed around a portion of
a fastener, e.g., around the rod-receiving head 104 of bone screw
100. While various techniques can be used to mate the jaws 24, 26
to the bone screw 100, in the illustrated embodiment the jaws 24,
26 are connected by a u-spring 28. The u-spring 28 allows the jaws
24, 26 to be flexed apart, e.g., in a radial direction, from a
first, relaxed position to facilitate advancement of the jaws 24,
26 longitudinally over the rod-receiving head 104, and when
released the u-spring 28 biases the jaws 24, 26 back to an initial
position in which the jaws 24, 26 can provide a radially
compressive force towards the rod-receiving head 104. In
alternative embodiments, the jaws 24, 26 can be connected at a
pivot point by a hinge or by other mechanisms for allowing movement
between the jaws 24, 26.
[0038] In another embodiment, as shown in FIG. 12 which illustrates
a device 10' that is similar to device 10, at least one of the
jaws, e.g., the first jaw 24', can include a proximal extension
24e' that can be used to move the jaws 24', 26' apart to facilitate
positioning of the jaws 24', 26' around a fastener. In particular,
the first jaw 24' can have a length that is greater than a length
of the second jaw 26' such that a proximal end of the first jaw 24'
extends proximally beyond a proximal end of the second jaw 26'.
This allows the proximal extension 24e' to be grasped and moved
toward the second arm 62', thereby moving the distal end of the
first jaw 24' away from the distal end of the second jaw 26' to
open the jaws 24', 26' for positioning around a fastener. A person
skilled in the art will appreciate that a variety of other
techniques can also be used to move the jaws to an open position to
facilitate positioning around a fastener.
[0039] The jaws 24, 26 can also include various features to
facilitate mating to a fastener. For example, each jaw 24, 26 can
include at least one mating element disposed on an inner surface of
a distal end 24d, 26d thereof. By way of a non-limiting example,
the mating element can be in the form of at least one projection 30
that extends into at least one detent formed in the rod-receiving
head 104, as previously discussed. Exemplary mating techniques are
described in more detail in United States Publication No.
2006/0293692 of Whipple et al., filed on Jun. 5, 2005 and entitled
"Instruments and Methods for Manipulating a Spinal Fixation
Device," U.S. patent application Ser. No. 11/539,496 of Dziedzic et
al., filed on Oct. 6, 2006 and entitled "Minimally Invasive Bone
Anchor Extension," U.S. Publication No. 2006/0079909 of Runco et
al., filed on Sep. 26, 2005 and entitled "Instruments and Methods
for Bone Anchor Engagement and Spinal Rod Reduction," and in U.S.
Publication No. 2005/0149053 of Varieur et al., filed on Dec. 15,
2003 and entitled "Instruments and Methods for Bone Anchor
Engagement and Spinal Rod Reduction," which are hereby incorporated
by reference in their entireties. A person skilled in the art will
appreciate that the size, shape, and number of mating elements
formed on each jaw 24, 26 can vary depending on the configuration
of the fastener and the type of connection desired. Still in other
embodiments, rather than having jaws 24, 26, the fastener engaging
member 20 can include any number of arms, or can have other
configurations known in the art for engaging a fastener.
[0040] While not necessary, the fastener engaging member 20 can
also include a retainer ring 32 disposed around the jaws 24, 26 in
order to prevent the jaws 24, 26 from collapsing inwards. In the
illustrated embodiment, the retainer ring 32 is disposed around an
intermediate portion of the jaws 24, 26 at a location proximal to
the u-spring 28. This configuration will prevent a proximal end
24p, 26p of each jaw 24, 26 from moving further apart from one
another, thereby preventing the distal ends 24d, 26d of each jaw
24, 26 from collapsing inward. The jaws 24, 26 can also include one
or more flanges 34 formed adjacent to one of or both ends of the
retainer ring 32 to assist in holding the retainer ring 32 in
place.
[0041] As previously indicated, the device 10 can also include a
reduction member 40 that is movably coupled to the fastener
engaging member 20 and that is effective to reduce a spinal
fixation element, such as spinal rod 108, into a fastener, such as
bone screw 100. The reduction member 40 can be configured in a
variety of different ways and with any number of components. In the
illustrated embodiment, the reduction member 40 is in the form of a
sleeve that is disposed around the jaws 24, 26. A distal end of the
reduction member 40 can be configured to abut against a spinal
fixation element extending between the opposed jaws 24, 26 of the
fastener-engaging member 20, and a proximal end can be coupled to
an actuator or handle assembly, as will be discussed in more detail
below, for moving the reduction member 40. While not shown, the
reduction member 40 can also include features to facilitate
engagement with a spinal fixation element. For example, the
reduction member 40 can include at least one leg formed on a distal
end thereof. The leg(s) can include a recess adapted to receive the
spinal fixation element to assist in reducing the spinal fixation
element into the fastener. A person skilled in the art will
appreciate that any number of legs and/or recesses, or any type of
mechanism that is effective to assist with placing a spinal
fixation element into a fastener, can be used.
[0042] In use, the reduction member 40 can be adapted to slide
along the fastener engaging member 20 to allow the reduction member
40 to advance a spinal fixation element into a fastener engaged by
the fastener engaging member 20. In an exemplary embodiment, the
reduction member 40 can move along a longitudinal axis L of the
fastener engaging member 20, as shown in FIG. 3, in order to reduce
the spinal rod 108 into the bone screw 100. In particular, the
reduction member 40 can be moved between an initial position in
which the reduction member 40 is either disengaged with the spinal
rod 108 or is placing a negligible force on the rod 108, and a
final position in which the reduction member 40 is engaged (i.e.,
in contact) with the spinal rod 108 and applies a force to the rod
108 to reduce the rod 108 into the bone screw 100. In the initial
position, as shown in FIG. 1, the reduction member 40 can be
positioned proximal of the distal end 24d, 26d of the jaws 24, 26.
In this position, the spinal rod 108 can be disposed between the
jaws 24, 26 of the fastener engaging member 20. When the reduction
member is slid distally into the final position, as shown in FIG.
2, the reduction member 40 can be positioned adjacent to, i.e.,
approximately even with or just proximal or distal to, the distal
end 24d, 26d of the jaws 24, 26 in order to reduce the rod 108 into
the bone screw 100. As further shown in FIG. 2, the reduction
member 40 can also be effective to lock the jaws 24, 26 in a fixed
position relative to the bone screw 100 when the reduction member
40 is in or near the final position. A person skilled in the art
will appreciate that the reduction member 40 can be located in any
number of positions and that the initial and final positions can
vary depending on the location and configuration of the spinal
fixation element and the fastener. Moreover, a person skilled in
the art will appreciate that the reduction member does not need to
move along the longitudinal axis L of the fastener engaging member
20 in order to perform rod reduction, but rather it can travel in
any direction, but preferably in a direction that allows the action
of reduction to occur.
[0043] In order to move the reduction member 40 between the initial
and final positions, the device 10 can further include an actuator
or handle assembly 60. The handle assembly 60, which is best
illustrated in FIGS. 1 and 2, can have a variety of configurations.
In the illustrated embodiment, the handle assembly 60 includes
first and second arms 62, 64 that are pivotally coupled to one
another. The first arm 62 can have a proximal grasping portion 62p
and a distal portion 62d that is mated to the fastener engaging
member 20, and the second arm 64 can have a proximal grasping
portion 64p and a distal portion 64d that is coupled to a linkage
80 such that movement of the second arm 64 relative to the first
arm 62 causes the reduction member 40 to move relative to the
fastener engaging member 20. The shape of each arm 62, 64 can vary,
but in an exemplary embodiment the first arm 62 is substantially
L-shaped such that the proximal portion 62p of the first arm 62
extends substantially parallel to the longitudinal axis L of the
fastener engaging member 20 and the distal portion 62d of the first
arm 62 extends substantially transverse to the proximal portion 62p
of the first arm 62. The first arm can be fixedly or movably mated
to the fastener engaging member 20 at a variety of locations. In an
exemplary embodiment, the distal portion 62d of the first arm 62 is
fixedly mated to the proximal end 24p of the first jaw 24. As
shown, the distal portion 62d of the first arm 62 can include a
forked extension 66 that receives the proximal end 24p of the first
jaw 24. As further shown in FIGS. 1 and 2, the second arm 64 can
have a generally elongate substantially linear shape, and it can be
pivotally coupled to the first arm 62, e.g., using a pin or similar
mating element. While the pivot location can vary, in the
illustrated embodiment the pivot 70 is located at a mid-portion of
the second arm 64 and on the distal portion 62d of the first arm
62. The second arm 64 can include a forked extension 68 formed in
the distal portion 64d thereof for receiving the distal end 62d of
the first arm 62 therebetween. The illustrated forked extension 68
of the second arm 64 begins at a mid-portion and extends distally.
The arms 62, 64 can also optionally include features that assist in
the comfort and ease of use of the device 10. Any number of
features can be included to provide such comfort and ease of use.
For example, the arms 62, 64 can include surface features to
facilitate engagement, such as finger grips, which are represented
in the FIGS. by contours or depressions 67 formed in the respective
proximal portions 62p, 64p of the arms 62, 64.
[0044] Actuation of the handle assembly 60 can be achieved by
moving one of the grasping proximal portions 62p, 64p of the first
and second arms 62, 64 toward the other one of the grasping
proximal portions 62p, 64p of the first and second arms 62, 64, or
alternatively, by moving both of the grasping proximal portions
62p, 64p toward each other. In the illustrated embodiment, the
second arm 64 functions as an actuator that can be moved toward the
first arm 62. Such movement causes the distal portion 64d of the
second arm 64 to move toward the longitudinal axis L of the
fastener engaging member 20 such that the distal portion 64d of the
second arm 64 extends substantially parallel to both the fastener
engaging member 20 and the grasping proximal portion 62p of the
first arm 62. The distal portion 64d of the second arm 64 can also
crossover beyond the longitudinal axis of the fastener engaging
member 20 and the grasping proximal portion 62p of the first arm
62.
[0045] In order for movement of the arms 62, 64 to be effective to
move the reduction member 40, the device 10 can also include a
linkage 80, or other similar mechanism known in the art, coupled
between the second arm 64 and the reduction member 40. The linkage
80, which is shown in more detail in FIG. 4, can have a variety of
configurations. In the illustrated embodiment, the linkage 80
includes first and second bars 82, 84 positioned on opposed sides
of the fastener engaging member 20. Each bar 82, 84 can include a
proximal end 82p, 84p and a distal end 82d, 84d, respectively. The
proximal ends 82p, 84p of the first and second bars 82, 84 can be
pivotally mated to the distal portion 64d of the second arm 64,
i.e., to the terminal ends of the forked extension 68, and the
distal ends 82d, 84d of the first and second bars 82, 84 can be
mated to the reduction member 40. A person skilled in the art will
recognize that any number of methods for mating the linkage 80 to
the second arm 64 and the reduction member 40 can be used,
including, for example, a pin. In use, the linkage 80 can extend
between an initial position in which the linkage extends
substantially transverse to the longitudinal axis L of the fastener
engaging member 20, as shown in FIG. 1, and a final position in
which the linkage 80 extends substantially parallel to the
longitudinal axis L of the fastener engaging member 20, as shown in
FIG. 2. In particular, as described above with respect to the arms
62, 64, movement of the proximal grasping portion 64p of the second
arm 64 toward the proximal grasping portion 62p of the first arm 62
will cause the distal portion 64d of the second arm 64 to move
toward the longitudinal axis L. The distal portion 64d will thus
move the proximal ends 82p, 84p of the first and second bars 82, 84
toward the longitudinal axis L of the fastener engaging member 20.
Because the distal ends 82d, 84d of the first and second bars 82,
84 are mated to the reduction member 40, the reduction member 40 is
subsequently moved toward the distal end 24d, 26d of the jaws 24,
26 as the linkage 80 moves toward the final position. As a result,
the fastener engaging member 20 can reduce the rod 108 into the
bone screw 100.
[0046] A person skilled in the art will appreciate that, while the
device 10 of FIG. 1 includes a linkage 80 having two bars 82, 84
that are straight, the linkage can have a variety of other
configurations. FIG. 12 illustrates another embodiment of a spinal
rod reduction device 10' that is similar to device 10, except that
the linkage 80' has two bars 82', 84' that each have a curved
shaped. In use, the linkage 80' functions similar to the linkage 80
of FIG. 1. Namely, the linkage 80' can extend between an initial
position in which the bars 82', 84' extend substantially transverse
to a longitudinal axis L' of the fastener engaging member 20', and
a final position in which the bars 82', 84' extend substantially
parallel to the longitudinal axis L' of the fastener engaging
member 20', as shown in FIG. 12. While the bars 82', 84' are
curved, at least the proximal and distal pivots points at which the
bars 82', 84' pivotally mate to the distal portion 64d' of the
second arm 64' and the reduction member 40' can be aligned with the
longitudinal axis L'.
[0047] Exemplary methods for reducing a spinal fixation element,
such as a spinal rod 108, into a fastener, such as a bone screw
100, are also provided. In one embodiment, one or more bone screws
100 can be implanted in one or more vertebra using known surgical
techniques and the spinal rod 108 can be positioned to span across
the bone screw(s) 100. Since multiple bone screw implanted in
adjacent vertebrae are not always aligned with one another, the
spinal rod 108 may be positioned a distance above one or more of
the bone screws 100, and thus reduction of the rod 108 into the
screws(s) 100 is necessary. Accordingly, a fastener engagement
member 20 can be engaged with a bone screw 100. In particular, the
proximal ends 24p, 26p of the jaws 24, 26 can be squeezed together
to move the distal ends 24d, 26d of the jaws 24, 26 apart, thereby
allowing the jaws 24, 26 to be positioned around the rod-receiving
head 104 of the bone screw 100. Once the jaws 24, 26 are positioned
around the rod-receiving head 104 of the bone screw 100, the
proximal ends 24p, 26p of the jaws 24, 26 can be released to allow
the mating elements on the fastener engaging member 20 to engage
the detents in the bone screw 100.
[0048] Once the fastener engaging member 20 is engaged with at
least a portion of the bone screw 100, the handle assembly can be
operated in order to reduce the rod 108 into the bone screw 100. In
particular, as discussed above, the second arm 64 of the device 10
can be pivoted relative to the first arm 62 to cause the proximal
portion 64p of the second arm 64 to move toward the proximal
portion 62p of the first arm 62. Movement of the second arm 64 will
in turn cause the linkage 80 to move distally, thereby advancing
the reduction member 40 distally toward the bone screw 100 into its
final position. As a result, the spinal rod 108 will be advanced
into the rod-receiving head 104 of the bone screw 100. The
reduction member 40 also lock the jaws 24, 26 in a fixed position
relative to the bone screw 100 as it will extend around the jaws
24, 26 to prevent them from opening. Locking can occur prior to the
full reduction of the spinal rod 108 into the bone screw 100, or it
can occur simultaneously.
[0049] Once the final position has been reached and the spinal rod
108 has been reduced into the bone screw 100, a rod retainer, such
as a set screw, can be delivered to the bone screw 100 to lock the
rod 108 into the screw 100. In an exemplary embodiment, the rod
retainer is delivered through the pathway 22 extending through the
fastener engaging member 20. The pathway, as seen in FIG. 5, can be
a linear pathway extending between the arms 62, 64 and extending
through the fastener engaging member 20. This linear pathway can
provide an easy viewing area for performing the reduction and
subsequently delivering the rod retainer. Once the rod retainer is
delivered to the bone screw 100, it can be applied to the bone
screw 100 using various techniques, such as threads or a twist-lock
connection. An instrument, such as a driver, can be placed within
the pathway 22 to assist in delivering and applying the rod
retainer to the bone screw 100.
[0050] In another embodiment, the first arm 62 can be removable to
allow a fastener engaging member 20 to be mated to a bone screw 100
before attaching the first arm 62 to the fastener engaging member
20. This can be advantageous where multiple bone screws are
disposed in adjacent vertebrae and multiple fastener engaging
members are engaged with each bone screw prior to performing any
reductions. Once the fastener engaging members are in place, a
single arm can be sequentially mated to each fastener engaging
member to reduce the spinal rod into the bone screws.
[0051] FIGS. 6 and 7 illustrate another exemplary embodiment of a
spinal rod reduction device 110. The device 110 is similar to
device 10 in that it generally includes a fastener engaging member
120 adapted to engage at least a portion of a fastener, a reduction
member 140 movably coupled to the fastener engaging member 20, and
a handle assembly 160 mated to the reduction member 140 and adapted
to move the reduction member 140 relative to the fastener engaging
member 120 to reduce a spinal fixation element into a fastener. In
this embodiment, rather than having a linkage, the device 110
includes a pusher member 180 that can both extend through a housing
182 mated to the fastener engaging member 120 and also can be mated
to the reduction member 140. The handle assembly 160 is configured
to advance the pusher member 180 distally which in turn is
effective to move the reduction member 140 and reduce the spinal
fixation element into the fastener.
[0052] The illustrated fastener engaging member 120 is similar to
fastener engaging member 20 and it generally includes first and
second opposed jaws 124, 126 with proximal ends 124p, 126p and
distal ends 124d, 126d, respectively, and a pathway 122. Similar to
device 10, various techniques and features can be used to mate the
jaws 124, 126 to allow movement between the jaws 124, 126, such as
a u-spring 128, and also similar to device 10, the jaws 124, 126
can be flexed apart, e.g., in the radial direction, from a first,
relaxed position to facilitate advancement of the jaws 124, 126
longitudinally over the rod-receiving head 104 of the bone screw
100 back to an initial position in which the jaws 124, 126 can
provide a radially compressive force on the rod-receiving head 104.
Furthermore, as previously described with respect to device 10, the
fastener engaging member 120 can also include various mating
elements to engage a fastener and/or a retainer ring 132 to prevent
the jaws 124, 126 from collapsing inwards.
[0053] As previously indicated, the device 110 can also include a
reduction member 140 that is movably coupled to the fastener
engaging member 120 and that is effective to reduce a spinal
fixation element, such as spinal rod 108, into a fastener, such as
bone screw 100. The illustrated reduction member 140 is similar to
the reduction member 40 previously described for device 10 and is
generally in the form of a sleeve disposed around the fastener
engaging member 120. In use, the reduction member 140 can move
along a longitudinal axis L' of the fastener engaging member 120
between an initial position and a final position as described above
with respect to device 10 to allow the reduction member 140 to
advance a spinal fixation element into a fastener engaged by the
fastener engaging member 120. Also similar to the device 10, the
reduction member 140 can be effective to lock the jaws 124, 126 in
a fixed position relative to the bone screw 100 when the reduction
member 140 is moved toward or into the final position.
[0054] In order to move the reduction member between the initial
and final positions, the device 110 can further include a pusher
member 180, such as a rod. A distal end 180d of the pusher member
180 can abut against the rod reduction member 140, but in an
exemplary embodiment the distal end 180d is fixedly mated to or
formed integrally with the rod reduction member 140. As shown in
FIG. 6, the rod reduction member 140 is formed on the distal end
180d of the pusher member 180. The pusher member 180 can also
extend offset from but substantially parallel to a longitudinal
axis L' of the fastener engaging member 120, and thus the distal
end 180d of the pusher member 180 can extend at an angle relative
to an axis of the remainder of the pusher member 180 and toward
longitudinal axis L' of the fastener engaging member 120 to allow
the pusher member 180 to mate to the reduction member 140.
[0055] As further shown in FIG. 6, at least a portion of the pusher
member 180 can be slidably disposed within a housing 182. In one
embodiment, the housing 182 is a hollow elongate cylindrical member
with a proximal portion 182p and a distal portion 182d. The housing
182 can include an outer sidewall 184, which can optionally include
one or more openings 186 formed therein for facilitating viewing
and/or cleaning of the device 110. The outer sidewall 184 of the
housing 182 can be mated to the fastener engaging member 120 to
allow the pusher member 180 to apply a force to the reduction
member 140 while the housing maintains the fastener engaging member
120 in a fixed position. As shown in FIG. 6, an intermediate
portion of the housing 182 is fixedly mated to the proximal end
124p of the first jaw 124, and the distal portion of the housing
182d is fixedly mated to an intermediate portion of the fastener
engaging member 120. As a result, the housing 182, as well as the
pusher member 180 extending through the housing 182, is offset from
but substantially parallel to the longitudinal axis L' of the
fastener engaging member 120. A person skilled in the art will
appreciate that any number of connections and methods to make such
connections between the housing 182 and the fastener engaging
member 120 can be used.
[0056] As further shown in FIG. 6, the housing 182 can also include
an alignment extension 188 that can be aligned with the pathway 122
of the fastener engaging member 120 to assist in aligning various
devices with the fastener engaging member 120. The alignment
extension 188 can have any configuration, but in the illustrated
embodiment it is substantially c-shaped for receiving an
instrument, such as a screwdriver, therethrough and for aligning
the instrument with the pathway 122. The alignment extension 188
can be located anywhere on the housing 182, but in the illustrated
embodiment it is located on the proximal portion 182p of the
housing 182.
[0057] In use, the pusher member 180 can be slidably advanced
through the housing 182 to cause distal movement of the reduction
member 140 along the fastener engaging member 120 to thereby reduce
the spinal rod 108 into the bone screw 100. In particular, the
pusher member 180 can travel substantially parallel to the
longitudinal axis L' of the fastener engaging member 120 from an
initial position, shown in FIG. 6, in which a distal-most end of
the pusher member 180, and thus the reduction member 140, is
proximal or adjacent to the u-spring 128 between the jaws 124, 126
to allow the jaws 124, 126 to flex open and engage a bone screw, to
a final position in which the distal-most end of the pusher member
180, and thus the reduction member 140, is adjacent to the distal
ends 124d, 126d of the jaws 124, 126, as shown in FIG. 7 to thereby
reduce a rod into a bone screw.
[0058] In order to move the pusher member 180 between the initial
and final positions, the device 110 can further include a handle
assembly 160. The handle assembly 160, which is best illustrated in
FIGS. 6 and 7, can have a variety of configurations. In the
illustrated embodiment, the handle assembly 160 includes first and
second arms, hereinafter referred to as a handle 162 and an
actuator 164, that are pivotally coupled to one another. The handle
162 can have a proximal grasping portion 162p and a distal portion
162d that is coupled to the proximal end 182p of the housing 182 at
a pivot point 183. The housing 182 can optionally include a flared
portion 190 that allows for easy mating between the housing 182 and
the handle 162. The handle 162 can also be integrally formed with
the housing 182. The actuator 164 can also include a proximal
grasping portion 164p and a distal portion 164d that is coupled to
the proximal end 180p of the pusher 180 at a pivot point 165. As
indicated above, the handle 162 and the actuator 164 can be
pivotally mated to one another. While the pivot location can vary,
in the illustrated embodiment a pivot 166 is located at
mid-portions of the handle 162 and the actuator 164. The pivot 166
can be in the form of a pin extending through the handle 162 and
the actuator 164, although a person skilled in the art will
appreciate that any known component capable of allowing pivotable
movement between the handle 162 and the actuator 164 can be
used.
[0059] The handle assembly can also include a biasing element 168
adapted to bias at least one of the handle 162 and the actuator 164
in one of an open or a closed position. The biasing element 168 can
be disposed between the handle 162 and the actuator 164, or it can
be located in any other location that allows for one of the handle
162 and the actuator 164 to be biased to at least one of the open
or closed positions. In the illustrated embodiment, the biasing
element 168 is two leaf springs, with the first leaf spring 172
mated at a proximal end 172p thereof to an inner surface of the
proximal grasping portion 162p of the handle 162 and the second
leaf spring 174 mated at a proximal end 174p thereof to an inner
surface of the proximal grasping portion 164p of the actuator 164.
The first and second leaf springs 172, 174 can be connected at
distal ends 172d, 174d thereof. As a result, the biasing mechanism
168 will maintain the handle assembly in the open position, as
shown in FIG. 6, and a force sufficient to overcome the biasing
force will need to be applied to the handle assembly 160 to move it
toward the closed position, which is shown in FIG. 7.
[0060] The handle 162 and the actuator 164 can also optionally
include features that assist in the comfort and ease of use of the
device 110. Any number of features can be included to provide such
comfort and ease of use. For example, the proximal grasping portion
164p of the actuator 164 can include a loop 176 which provides an
area for fingers to be placed during use of the device 110, and the
proximal grasping portion 162p of the handle 162 can include a
thumb stop 178, which provides an area for the thumb to be placed
during use of the device 110.
[0061] The handle assembly 160 can be actuated by moving one of the
grasping proximal portions 162p, 164p of the handle 162 and the
actuator 164, respectively, toward the other one of the proximal
portions 162p, 164p of the handle 162 and the actuator 164, or
alternatively, by moving both of the grasping proximal portions
162p, 164p toward each other. In the illustrated embodiment, the
handle 162 is pivotally connected to the housing 182 at the pivot
point 183 and thus can pivot as the actuator 164 pivots about pivot
point 166 toward the handle 162. Such movement can cause the distal
end 164d of the actuator 164 to move toward the distal end 162d of
the handle 162 thereby causing the pusher member 180 to advance
distally toward the reduction member 140 to reduce the spinal rod
108 into the bone screw 100. Alternatively, the handle 162 can be
fixed to the housing 182 at point 183 while the actuator 164 is
movably coupled to the proximal portion of the pusher 180 at pivot
point 165. In other words handle 162 shown in FIGS. 6 and 7 can
form a fixed handle while actuator 164 shown in FIGS. 6 and 7
remains movably coupled to the pusher. Such a configuration will
likewise result in movement of the pusher 180 relative to the
reduction member 140 to reduce a spinal rod 108 into a bone screw
100.
[0062] Exemplary methods for reducing a spinal fixation element
into a fastener using device 110 are also provided. As previously
discussed, a bone screw 100 can be implanted in a vertebra using
known surgical techniques and the fastener engaging member 120 can
be mated to the bone screw 100. The fastener engaging member 120
can be positioned around a spinal rod 108, positioned above the
bone screw 100, such that the rod 108 extends between the jaws 124,
126 of the fastener engaging member 120. Once the fastener engaging
member 120 is mated to the bone screw 100, the pusher member 180
can be moved through the housing 182 toward the bone screw 100 to
advance the reduction member 140 toward the bone screw 100. In
particular, the proximal grasping portion 164p of the actuator 164
can be pivoted toward the proximal grasping portion 162p of the
handle 162 to cause the pusher member 180 to move distally, thereby
advancing the reduction member 140 distally toward the bone screw
100 into its final position. As a result, the spinal rod 108 will
be advanced into the rod-receiving head 104 of the bone screw 100.
The reduction member 140 can also lock the jaws 124, 126 in a fixed
position relative to the bone screw 100. Locking can occur prior to
the full reduction of the spinal rod 108 into the bone screw 100,
or it can occur simultaneously. Once the final position has been
reached and the spinal rod 108 has been reduced into the bone screw
100, a rod retainer, such as a set screw, can be delivered to the
bone screw 100. An instrument such as a driver can be positioned
through the alignment extension 188 and the pathway 122 to deliver
and apply the rod retainer to the bone screw 100.
[0063] The various devices discussed herein, as well as other
devices known in the art, can also include a locking mechanism that
is adapted to maintain the reduction member in a desired fixed
position. The desired fixed position can be any position between
and including the initial and final positions as described above.
FIGS. 6 and 7 illustrate one exemplary embodiment of a locking
mechanism 200 for locking the reduction member 140 in a fixed
position relative to the fastener engaging member 120. As shown,
locking mechanism 200 is in the form of a catch bar 204 that is
coupled to the proximal grasping portion 162p of the handle 162 and
that is adapted to engage a notch 202 formed in a proximal grasping
portion 164p of the actuator 164. The catch bar 204 can be
generally elongate, and on one end it can be pivotally mated to the
proximal grasping portion 162p of the handle 162 at a pivot point
208. This pivotal connection allows the catch bar 204 to move
between various positions, as will be discussed below. The other
end of the catch bar 204 can include a latch 206 that is configured
to engage the notch 202.
[0064] In use, the catch bar 204 can be moved between an engaged
and a disengaged position by engaging and disengaging the latch 206
from the notch 202. When the catch bar 204 is in the engaged
position, as shown in FIG. 7, the handle 162 and the actuator 164
are maintained in a fixed position relative to one another, which
in turn means that the pusher member 180 and the reduction member
140 coupled thereto are also maintained in a fixed position because
of the communication between the pusher member 180 and the handle
assembly 160. When the catch bar 204 is in the disengaged position,
as shown in FIG. 6, the handle 162 and/or the actuator 164 can move
freely, which in turn means that the pusher member 180 and the
reduction member 140 coupled thereto can also move freely. In the
illustrated embodiment, the catch bar 204 is pivotally mated to the
proximal grasping portion 162p of the handle 162 at the pivot point
208, and thus the catch bar 204 can be located in a variety of
places when it is in the disengaged position. For example, the
catch bar 204 can be substantially parallel to the handle 162 with
a distal end 204d of the catch bar being directed either toward the
device 110 or away from the device 110. By way of another example,
the catch bar 204 can be substantially transverse to the handle 162
with the distal end 204d of the catch bar 204 being directed
proximally away from the device 110. The catch bar 204 can be
rotated or snapped into the variety of disengaged positions.
[0065] FIG. 8 illustrates another embodiment of a locking mechanism
200' having a catch bar 204' that includes a threaded collar 210'
rotatably (or threadably) coupled to the catch bar 204' and that is
adapted to adjust an effective length of the catch bar 204' to
allow the locking mechanism 200' to maintain the reduction member
140 in a number of different positions. More particularly, rotation
of the threaded collar 210' can allow the latch 206' to move toward
and away from a pivot point 208', thereby adjusting the effective
length of the catch bar 204'. As a result, the catch bar 204' will
maintain the handle 162 and the actuator 164 at a desired,
operator-selected distance apart, which in turn maintains the
pusher member 180 and the reduction member 140 coupled thereto in a
desired, operator-selected position because of the communication
between the pusher member 180 and the handle assembly 160.
Similarly, the threaded collar 210' could be rotatably coupled to
the handle portion 162p, while the catch bar 204' with latch 206'
can be moved toward and away from a pivot point 208' by rotation of
threaded collar 210'.
[0066] FIG. 9 illustrates another embodiment of a locking mechanism
220. In this embodiment, the locking mechanism 220 includes a
locking pin 226 coupled to a housing 282, as well as a series of
notches 222 formed in a proximal end 280p of a pusher member 280 of
a device 210 having a configuration similar to device 110 of FIGS.
6 and 7. The locking pin 226 can have a generally elongate shape
with a proximal end 226p positioned outside of the housing 282
formed on the handle of the device 210, and a distal end 226d
disposed within the housing 282 and adapted to selectively engage
the series of notches 222. The locking pin 226 can be movable
between an engaged position, shown in FIG. 9, in which the distal
end 226d is in contact with the notches 222, and a disengaged
position, in which the distal end 226d is spaced a distance apart
from the pusher member 280. A person skilled in the art will
appreciate that, while a series of notches 222 is shown, the pusher
member 280 can include a single notch.
[0067] In an exemplary embodiment, the locking pin 226 can be
biased to the engaged position. As shown in FIG. 9, the device
includes a spring 228 disposed within the housing 282 and around
the locking pin 226. The spring can extend between a flange 227
formed adjacent to the distal end 226d of the locking pin 226 and a
portion of the housing 282 through which the pin 226 extends. As a
result, the spring 228 applies a force to the flange 227, thereby
biasing the pin 226 toward and into engagement with the notches
222. FIG. 9 illustrates a nut or screw 230 disposed within the
housing 282 and having the locking pin 226 extending through a bore
formed therein. The screw 230 can be provided for allowing
insertion of the spring 228 into the housing 282 during
manufacturing of the device. A person skill in the art will
appreciate that the spring 228 can alternatively bias the locking
pin 226 into a disengaged position, in which the locking pin 226 is
spaced apart from the series of notches 222 in the pusher member
280, and thus the pusher member 280 and the reduction member
coupled thereto can move freely.
[0068] The locking mechanism 220 can also include a release 232
coupled to the proximal end 226p of the locking pin 226 to unbias
the locking pin 226 and place the locking pin 226 in the disengaged
position. In the illustrated embodiment, the release 232 is in the
form of a handle extending from or formed integrally with the
proximal end 226p of the locking pin 226. As shown, a proximal end
232p of the release 232 can be curved to allow a finger to grasp
the release 232. In use, movement of the release 232 in a direction
indicated by arrow F will pull the locking pin 226 out of
engagement with the notches 222, thereby allowing free movement of
the pusher member 280 and the reduction member coupled thereto. A
person skilled in the art will appreciate that the release can have
a variety of other configurations and it can be coupled to any
component of the device, including the screw 230, the spring 228,
or the locking pin 226, to selectively move the locking pin 226
between the engaged and disengaged positions.
[0069] As further shown in FIG. 9, the locking mechanism 220 can
also include a blocking mechanism adapted to prevent the locking
pin 226 from engaging the series of notches 222. In the illustrated
embodiment, the blocking mechanism is a nut 234 that is threadably
disposed around the proximal end 226p of the locking pin 226 and
that is located outside of the housing 282. In use, the nut 234 can
be rotated relative to the locking pin 226 to pull the locking pin
226 away from the notches 222. Since the nut 234 abuts against the
housing, and in particular against the screw 230, the nut 234 will
maintain the locking pin 226 in the disengaged positions. Threading
the nut 234 in the opposite direction can place the locking pin 226
back into the engaged position. A person skilled in the art will
appreciate that there are a number of different ways to design the
blocking mechanism so that it selectively places the locking pin
226 in the engaged and disengaged positions.
[0070] FIG. 10 illustrates yet another embodiment of a locking
mechanism 240 that includes a locking pawl 246 coupled to a flared
portion 390 of a housing 382 and a series of notches 242 formed in
a pusher member 380 of a device 310. The locking pawl 246 has a
first end 246b flexibly or pivotally coupled to the housing 382 and
a second, engaging end 246a for selective engagement with the
series of notches 242 formed in the pusher member 380. An extension
248 can be mated to the locking pawl 246 for moving the locking
pawl 246 between the engaged and disengaged positions. In the
illustrated embodiment, the extension 248 is a rigid member that
extends substantially perpendicular to the pusher member 380 and
that is mated to the second, engaging end 246a of the locking pawl
246 such that movement of the extension 248 causes the locking pawl
246 to move between an engaged position, in which the locking pawl
246 engages the notches 242 and the pusher member 380 to maintain
the pusher member 380 and a reduction member (not shown) coupled
thereto in a fixed position, and a disengaged position, in which
the locking pawl 246 is spaced apart from the series of notches 242
to allow the pusher member 380 and the reduction member coupled
thereto to move freely. The locking pawl 246 can optionally be
biased in either the engaged or disengaged position by a biasing
element. While the biasing element can be any component that biases
the locking pawl 246 into the engaged or disengaged position, in
one embodiment the locking pawl 246 is a leaf-spring pawl that is
biased in the engaged position. The locking mechanism 240 can also
include a blocking mechanism adapted to prevent the locking pawl
246 from engaging the series of notches 242. In the illustrated
embodiment, the blocking mechanism is a nut 254 that is threadably
disposed around the proximal end 380p of the pusher member 380. The
nut 254 can be moved relative to the pusher member 380 to position
the nut 254 between the locking pawl 246 and the notches 242. A
person skilled in the art will appreciate that, while a series of
notches 242 is shown, the pusher member 380 can include a single
notch.
[0071] In use, as shown in the illustrated embodiment, the locking
pawl 246 is biased in the engaged position because the locking pawl
246 is a leaf-spring pawl. In order to allow movement of the pusher
member 380, and in turn the reduction member 340, the extension 248
can be pulled in a direction indicated by arrow D substantially
transverse to the pusher member 380 to place the locking pawl 246
in the disengaged position. In another embodiment, the extension
can be pulled in a direction indicated by arrow T toward a distal
end of the pusher member 380 to place the locking pawl 246 in the
disengaged position. Alternatively, if the locking pawl 246 is
already in the disengaged position, the extension 248 can be moved
in the approximate opposite directions as described above to bias
the locking pawl 246 into the engaged position. The locking pawl
246 can also be placed in the disengaged position by operating the
blocking mechanism. In the illustrated embodiment, the blocking
mechanism is operated by threading the nut 254 toward the distal
end of the pusher member 380 in order to prevent the locking pawl
246 from engaging the series of notches 242, i.e., it places the
locking pawl 246 in the disengaged position because the nut 254 is
disposed between the locking pawl 246 and the series of notches
242. A person skilled in the art will appreciate that there are a
number of different ways to design the blocking mechanism so that
it places the locking pawl 246 in the disengaged position.
[0072] FIGS. 11A-11D illustrate another embodiment of a locking
mechanism 260 having a locking pawl 266 disposed on a bar 268 and
at least one notch 262 formed in the pusher member. The bar 268 can
extend through a housing 182 of a device 110 in a direction
substantially transverse to a pusher member 180, and the locking
pawl 266 can be formed on a portion thereof to allow the locking
pawl 266 to move into and out of at least one notch 262 formed in
the pusher member 180 as the bar 268 is moved relative to the
housing 182. The locking mechanism 260 can further include at least
one biasing mechanism adapted to bias the bar 268 toward the pusher
member 180 such that the locking pawl 266 engages the notch 262 to
maintain the pusher member 180 and the reduction member 140 coupled
thereto in a fixed position. In one embodiment, the biasing
mechanism can additionally include one or more spring members 272,
such as a spring-loaded ball plunger assembly. The bar 268 can also
include one or more recesses 274 on a bottom side thereof for
receiving the spring members 272. When the bar 268 is moved to
place the recesses 274 in alignment with the spring members 272
while the locking pawl 266 is not engaged with the pusher member
180 or notch 262, as shown in FIG. 11B, it will be held in that
position by the spring members 272. As a result, the locking pawl
266 is not in contact with the notch 262. Conversely, when the bar
268 is pushed to move the recesses 274 out of alignment with the
springs 272, the bar 268 is free to continue sliding transverse to
the pusher member 180 until the locking pawl 266 is in alignment
with pusher member 180 and notch 262. At that point, the spring
members 272 are once again in alignment with recesses 274 and thus
the locking pawl 266 will remain in the engaged position to prevent
movement of the pusher member 180 and the reduction member 140
coupled thereto. A biasing mechanism used to bias the bar 268
toward the pusher member 180 may also allow the bar 268 to move
away from the pusher member 180 far enough to permit the pawl 266
to engage the pusher member at a portion other than within the
notch 262, and the pawl 266 can then snap into engagement with the
notch 262 when the pusher member is actuated, such that the locking
pawl 266 subsequently maintains the pusher member 180 and the
reduction member 140 coupled thereto in a fixed position.
[0073] While a variety of locking mechanisms have been described
herein, a person skilled in the art will appreciate that there are
many different locking mechanisms that can be incorporated into the
various devices disclosed herein for maintaining a reduction member
in a desired fixed position. Furthermore, although various features
of the described locking mechanisms have been described for
particular illustrated embodiments, a person skilled in the art
will appreciate that many of these components are interchangeable
between the various embodiments and thus can be adapted for use in
the various described embodiments, as well as in other embodiments
known in the art.
[0074] A person skilled in the art will appreciate that the various
methods and devices disclosed herein can be formed from a variety
of materials. Moreover, particular components can be implantable
and in such embodiments the components can be formed from various
biocompatible materials known in the art. Exemplary biocompatible
materials include, by way of non-limiting example, composite
plastic materials, biocompatible metals and alloys such as
stainless steel, titanium, titanium alloys and cobalt-chromium
alloys, and any other material that is biologically compatible and
non-toxic to the human body.
[0075] One skilled in the art will appreciate further features and
advantages of the methods and devices based on the above-described
embodiments. Accordingly, the methods and devices are not to be
limited by what has been particularly shown and described, except
as indicated by the appended claims. All publications and
references cited herein are expressly incorporated herein by
reference in their entirety.
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