U.S. patent application number 17/176059 was filed with the patent office on 2021-06-17 for surgical access system and related methods.
The applicant listed for this patent is NuVasive, Inc.. Invention is credited to Jeffrey J. Blewett, Allen Farquhar, Eric Finley, James E. Gharib, Norbert F. Kaula, Scot Martinelli, Patrick Miles.
Application Number | 20210177391 17/176059 |
Document ID | / |
Family ID | 1000005417526 |
Filed Date | 2021-06-17 |
United States Patent
Application |
20210177391 |
Kind Code |
A1 |
Miles; Patrick ; et
al. |
June 17, 2021 |
SURGICAL ACCESS SYSTEM AND RELATED METHODS
Abstract
A system for accessing a surgical target site and related
methods, involving an initial distraction system for creating an
initial distraction corridor, and an assembly capable of
distracting from the initial distraction corridor to a secondary
distraction corridor and thereafter sequentially receiving a
plurality of retractor blades for retracting from the secondary
distraction corridor to thereby create an operative corridor to the
surgical target site, both of which may be equipped with one or
more electrodes for use in detecting the existence of (and
optionally the distance and/or direction to) neural structures
before, during, and after the establishment of an operative
corridor to a surgical target site.
Inventors: |
Miles; Patrick; (San Diego,
CA) ; Martinelli; Scot; (San Diego, CA) ;
Finley; Eric; (San Diego, CA) ; Gharib; James E.;
(San Diego, CA) ; Farquhar; Allen; (San Diego,
CA) ; Kaula; Norbert F.; (San Diego, CA) ;
Blewett; Jeffrey J.; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NuVasive, Inc. |
San Diego |
CA |
US |
|
|
Family ID: |
1000005417526 |
Appl. No.: |
17/176059 |
Filed: |
February 15, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16293223 |
Mar 5, 2019 |
10980524 |
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17176059 |
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14297369 |
Jun 5, 2014 |
10251633 |
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16293223 |
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13865598 |
Apr 18, 2013 |
8915846 |
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14297369 |
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13757035 |
Feb 1, 2013 |
8708899 |
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13865598 |
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13466398 |
May 8, 2012 |
8672840 |
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13757035 |
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12649604 |
Dec 30, 2009 |
8182423 |
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13466398 |
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12635418 |
Dec 10, 2009 |
8192356 |
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12649604 |
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12428081 |
Apr 22, 2009 |
7935051 |
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12635418 |
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10608362 |
Jun 26, 2003 |
7582058 |
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12428081 |
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60392214 |
Jun 26, 2002 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 17/0206 20130101;
A61B 2017/0262 20130101; A61B 17/025 20130101; A61B 1/32 20130101;
A61B 2017/00039 20130101; A61B 2017/0256 20130101; A61B 5/4893
20130101; A61B 17/02 20130101; A61B 2017/00026 20130101; A61B 5/296
20210101; A61B 17/0218 20130101; A61B 5/7405 20130101; A61B 17/0293
20130101; A61B 5/742 20130101 |
International
Class: |
A61B 17/02 20060101
A61B017/02; A61B 5/00 20060101 A61B005/00; A61B 5/296 20060101
A61B005/296; A61B 1/32 20060101 A61B001/32 |
Claims
1-20. (canceled)
21. A method for creating an operative corridor along a lateral,
trans-psoas path to a lumbar spine, comprising: delivering a first
retractor blade toward a spinal disc along a lateral, trans-psoas
path to the lumbar spine, the first retractor blade comprising: at
least one mounting arm configured to receive and lock with a blade
holder apparatus, a distal blade portion extending perpendicular to
the at least one mounting arm of the first retractor blade and
including an interior face and an exterior face, an intermediate
portion connecting between the distal blade portion and the at
least one mounting arm of the first retractor blade, and at least
one stimulation electrode disposed along the exterior face of the
distal blade portion and oriented oppositely away from the exterior
face of the distal blade portion; delivering a second retractor
blade toward the spinal disc along the lateral, trans-psoas path to
the lumbar spine at a position opposite from the first retractor
blade, the second retractor blade comprising: at least one mounting
arm configured to receive and lock with the blade holder apparatus,
a distal blade portion having the same shape and size as the distal
blade portion of the first retractor blade, extending perpendicular
to the at least one mounting arm of the second retractor blade, and
including an interior face and an exterior face, and an
intermediate portion connecting between the distal blade portion
and the at least one mounting arm of the second retractor blade;
delivering an elongate inner member toward the spinal disc along
the lateral, trans-psoas path to the lumbar spine; delivering a
first dilator to the spinal disc along the lateral, trans-psoas
path to the lumbar spine, the first dilator having a lumen
configured to slidably receive the elongate inner member; causing a
control unit to transmit an electrical stimulation signal to the at
least one stimulation electrode; causing the control unit to
receive an electromyographic (EMG) sensor signal of a neuromuscular
response of a nerve depolarized by the electrical stimulation
signal; and causing the control unit to, at a display device of the
control unit, display a graphical user interface with information
indicative of nerve proximity and nerve direction in response to
the EMG sensor signal.
22. The method of claim 21, wherein the one or more stimulation
electrodes of the first retractor blade are positioned proximate to
a distal most end of the distal blade portion of the first
retractor blade, wherein the second retractor blade further
comprises one or more stimulation electrodes disposed along the
exterior face of the distal blade portion of the second retractor
blade and oriented oppositely away from the exterior face of the
distal blade portion of the second retractor blade.
23. The method of claim 21, wherein the distal blade portion of the
first retractor blade defines a single tubular passageway fixedly
positioned relative to the at least one mounting arm of the first
retractor blade; wherein the method further comprises sliding a
first spine penetration member into the single tubular
passageway.
24. The method of claim 23, wherein the single tubular passageway
includes an upwardly facing opening and a downwardly facing opening
facing the downwardly facing opening toward the lumbar spine while
the first and second retractor blades maintain the operative
corridor along the lateral, trans-psoas path to the lumbar
spine.
25. The method of claim 21, wherein the distal blade portion of the
second retractor blade defines a single tubular passageway fixedly
positioned relative to the at least one mounting arm of the first
retractor blade; and wherein the method further comprises sliding a
first spine penetration member into the single tubular
passageway.
26. The method of claim 21, further comprising: positioning the one
or more stimulation electrodes of the first retractor blade
proximate to a distal most end of the distal blade portion of the
first retractor blade.
27. The method of claim 21, further comprising: mating the mounting
arm of the first retractor blade with a blade holder apparatus; and
mating the mounting arm of the second retractor blade with the
blade holder apparatus.
28. The method of claim 27, further comprising: locking the
mounting arm in relation to the blade holder apparatus so as to
maintain the operative corridor along the lateral, trans-psoas path
to the lumbar spine.
29. The method of claim 27, further comprising: adjusting the first
retractor blade and the second retractor blade relative to one
another so that the first retractor blade is spaced apart from the
second retractor blade.
30. The method of claim 27, wherein the at least one mounting arm
of the first retractor blade comprises first and second mounting
arms.
31. The method of claim 21, wherein at least a portion of the
exterior face of the distal blade portion of the first retractor
blade and at least a portion of the exterior face of the distal
blade portion of the second retractor blade have a cylindrical
surface region
32. The method of claim 21, wherein the at least one mounting arm
of the second retractor blade comprises first and second mounting
arms.
33. A method for creating an operative corridor along a lateral,
trans-psoas path to a lumbar spine, comprising: providing a first
retractor blade for use; receiving and locking a mounting arm of
the first retractor blade with a blade holder apparatus; delivering
the first retractor blade toward a spinal disc along a lateral,
trans-psoas path to the lumbar spine, the first retractor blade
comprising: at least one mounting arm, a distal blade portion
extending perpendicular to the at least one mounting arm of the
first retractor blade and including an interior face and an
exterior face, an intermediate portion connecting between the
distal blade portion and the at least one mounting arm of the first
retractor blade, and at least one stimulation electrode disposed
along the exterior face of the distal blade portion and oriented
oppositely away from the exterior face of the distal blade portion;
receiving and locking the mounting arm of the first retractor blade
with a blade holder apparatus; delivering a second retractor blade
toward the spinal disc along the lateral, trans-psoas path to the
lumbar spine at a position opposite from the first retractor blade,
the second retractor blade comprising: at least one mounting arm, a
distal blade portion having the same shape and size as the distal
blade portion of the first retractor blade, extending perpendicular
to the at least one mounting arm of the second retractor blade, and
including an interior face and an exterior face, and an
intermediate portion connecting between the distal blade portion
and the at least one mounting arm of the second retractor blade;
receiving and locking the mounting arm of the second retractor
blade with the blade holder apparatus; delivering an elongate inner
member toward the spinal disc along the lateral, trans-psoas path
to the lumbar spine; delivering a first dilator to the spinal disc
along the lateral, trans-psoas path to the lumbar spine, the first
dilator having a lumen configured to slidably receive the elongate
inner member; causing a control unit to transmit an electrical
stimulation signal to the at least one stimulation electrode;
causing the control unit to receive an electromyographic (EMG)
sensor signal of a neuromuscular response of a nerve depolarized by
the stimulation signal; and causing the control unit to, at a
display device of the control unit, display a graphical user
interface with information indicative of nerve proximity and nerve
direction in response to the EMG sensor signal.
34. The method of claim 33, further comprising sliding a first
spine penetration member into a tubular passageway of the first or
second retractor blade.
35. The method of claim 33, further comprising: positioning the one
or more stimulation electrodes of the first retractor blade
proximate to a distal most end of the distal blade portion of the
first retractor blade.
36. The method of claim 33, further comprising: mating the mounting
arm of the first retractor blade with a blade holder apparatus.
37. The method of claim 36, further comprising: mating the mounting
arm of the second retractor blade with the blade holder
apparatus.
38. The method of claim 37, further comprising: locking the
mounting arm in relation to the blade holder apparatus so as to
maintain the operative corridor along the lateral, trans-psoas path
to the lumbar spine.
39. The method of claim 33, further comprising: adjusting the first
retractor blade and the second retractor blade relative to one
another so that the first retractor blade is spaced apart from the
second retractor blade.
40. A method for creating an operative corridor along a lateral,
trans-psoas path to a lumbar spine, comprising: delivering a first
retractor blade toward a spinal disc along a lateral, trans-psoas
path to the lumbar spine, the first retractor blade comprising: at
least one mounting arm configured to receive and lock with a blade
holder apparatus, a distal blade portion extending perpendicular to
the at least one mounting arm of the first retractor blade and
including an interior face and an exterior face, an intermediate
portion connecting between the distal blade portion and the at
least one mounting arm of the first retractor blade, and at least
one stimulation electrode disposed along the exterior face of the
distal blade portion proximate a distal most end of the first
retractor blade, wherein the distal blade portion of the first
retractor blade defines a single tubular passageway with an
upwardly facing opening and a downwardly facing opening, the single
tubular passageway fixedly positioned relative to the at least one
mounting arm of the first retractor blade; delivering a second
retractor blade toward the spinal disc along the lateral,
trans-psoas path to the lumbar spine at a position opposite from
the first retractor blade, the second retractor blade comprising:
at least one mounting arm configured to receive and lock with the
blade holder apparatus, a distal blade portion having the same
shape and size as the distal blade portion of the first retractor
blade, extending perpendicular to the at least one mounting arm of
the second retractor blade, and including an interior face and an
exterior face, and an intermediate portion connecting between the
distal blade portion and the at least one mounting arm of the
second retractor blade, wherein the second retractor blade further
comprises at least one stimulation electrode disposed along the
exterior face of the distal blade portion of the second retractor
blade; delivering an elongate inner member toward the spinal disc
along the lateral, trans-psoas path to the lumbar spine; delivering
a first dilator to the spinal disc along the lateral, trans-psoas
path to the lumbar spine, the first dilator having a lumen
configured to slidably receive the elongate inner member; causing a
control unit to transmit an electrical stimulation signal to one or
more of the stimulation electrodes; causing the control unit to
receive an electromyographic (EMG) sensor signal of a neuromuscular
response of a nerve depolarized by the stimulation signal; and
causing the control unit to, at a display device of the control
unit, display a graphical user interface with information
indicative of nerve proximity and nerve direction in response to
the EMG sensor signal.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 16/293,223, which is a continuation of U.S.
patent application Ser. No. 14/297,369 (now U.S. Pat. No.
10,251,633) filed Jun. 5, 2014, which is a divisional of U.S.
patent application Ser. No. 13/865,598 filed Apr. 18, 2013 (now
U.S. Pat. No. 8,915,846), which is a continuation of U.S. patent
application Ser. No. 13/757,035 filed Feb. 1, 2013 (now U.S. Pat.
No. 8,708,899), which is a continuation of U.S. patent application
Ser. No. 13/466,398 filed May 8, 2012 (now U.S. Pat. No.
8,672,840), which is a continuation of U.S. patent application Ser.
No. 12/649,604 filed Dec. 30, 2009 (now U.S. Pat. No. 8,182,423),
which is a continuation of U.S. patent application Ser. No.
12/635,418 filed Dec. 10, 2009 (now U.S. Pat. No. 8,192,356), which
is a continuation of U.S. patent application Ser. No. 12/428,081
filed Apr. 22, 2009 (now U.S. Pat. No. 7,935,051), which is a
continuation of U.S. patent application Ser. No. 10/608,362 filed
Jun. 26, 2003 (now U.S. Pat. No. 7,582,058), which claims priority
to U.S. Provisional Patent Application No. 60/392,214 filed Jun.
26, 2002, the entire contents of these applications are hereby
expressly incorporated by reference into this disclosure as if set
forth fully herein. The present application also incorporates by
reference the following co-assigned patent applications in their
entireties: PCT App. No. PCT/US02/22247, entitled "System and
Methods for Determining Nerve Proximity, Direction. and Pathology
During Surgery," filed on Jul. 11, 2002 (published as WO03/005887);
PCT App. No. PCT/US02/30617, entitled "System and Methods for
Performing Surgical Procedures and Assessments." filed on Sep. 25,
2002 (published as WO 03/026482); PCT App. No. PCT/US02/35047,
entitled "System and Methods for Performing Percutaneous Pedicle
Integrity Assessments." filed on Oct. 30, 2002 (published as
WO/03037170); and PCT App. No. PCT/US03/02056, entitled "System and
Methods for Determining Nerve Direction to a Surgical Instrument,"
filed Jan. 15, 2003 (published as WO/2004064634).
BACKGROUND
I. Field
[0002] The present invention relates generally to systems and
methods for performing surgical procedures and, more particularly,
for accessing a surgical target site in order to perform surgical
procedures.
II. Description of Related Art
[0003] A noteworthy trend in the medical community is the move away
from performing surgery via traditional "open" techniques in favor
of minimally invasive or minimal access techniques. Open surgical
techniques are generally undesirable in that they typically require
large incisions and high amounts of tissue displacement to gain
access to the surgical target site, which produces concomitantly
high amounts of pain, lengthened hospitalization (increasing health
care costs), and high morbidity in the patient population.
Less-invasive surgical techniques (including so-called "minimal
access" and "minimally invasive" techniques) are gaining favor due
to the fact that they involve accessing the surgical target site
via incisions of substantially smaller size with greatly reduced
tissue displacement requirements. This, in turn, reduces the pain,
morbidity and cost associated with such procedures. The access
systems developed to date, however, fail in various respects to
meet all the needs of the surgeon population.
[0004] One drawback associated with prior art surgical access
systems relates to the ease with which the operative corridor can
be created, as well as maintained over time, depending upon the
particular surgical target site. For example, when accessing
surgical target sites located beneath or behind musculature or
other relatively strong tissue (such as, by way of example only,
the psoas muscle adjacent to the spine), it has been found that
advancing an operative corridor-establishing instrument directly
through such tissues can be challenging and/or lead to unwanted or
undesirable effects (such as stressing or tearing the tissues).
While certain efforts have been undertaken to reduce the trauma to
tissue while creating an operative corridor, such as (by way of
example only) the sequential dilation system of U.S. Pat. No.
5,792,044 to Foley et al., these attempts are nonetheless limited
in their applicability based on the relatively narrow operative
corridor. More specifically, based on the generally cylindrical
nature of the so-called "working cannula," the degree to which
instruments can be manipulated and/or angled within the cannula can
be generally limited or restrictive, particularly if the surgical
target site is a relatively deep within the patient.
[0005] Efforts have been undertaken to overcome this drawback, such
as shown in U.S. Pat. No. 6,524,320 to DiPoto, wherein an
expandable portion is provided at the distal end of a cannula for
creating a region of increased cross-sectional area adjacent to the
surgical target site. While this system may provide for improved
instrument manipulation relative to sequential dilation access
systems (at least at deep sites within the patient), it is
nonetheless flawed in that the deployment of the expandable portion
may inadvertently compress or impinge upon sensitive tissues
adjacent to the surgical target site. For example, in anatomical
regions having neural and/or vasculature structures, such a blind
expansion may cause the expandable portion to impinge upon these
sensitive tissues and cause neural and/or vasculature compromise,
damage and/or pain for the patient.
[0006] This highlights yet another drawback with the prior art
surgical access systems, namely, the challenges in establishing an
operative corridor through or near tissue having major neural
structures which, if contacted or impinged, may result in neural
impairment for the patient. Due to the threat of contacting such
neural structures, efforts thus far have largely restricted to
establishing operative corridors through tissue having little or
substantially reduced neural structures, which effectively limits
the number of ways a given surgical target site can be accessed.
This can be seen, by way of example only, in the spinal arts, where
the exiting nerve roots and neural plexus structures in the psoas
muscle have rendered a lateral or far lateral access path
(so-called trans-psoas approach) to the lumbar spine virtually
impossible. Instead, spine surgeons are largely restricted to
accessing the spine from the posterior (to perform, among other
procedures, posterior lumbar interbody fusion (PLIF)) or from the
anterior (to perform, among other procedures, anterior lumbar
interbody fusion (ALIF)).
[0007] Posterior-access procedures involve traversing a shorter
distance within the patient to establish the operative corridor,
albeit at the price of oftentimes having to reduce or cut away part
of the posterior bony structures (i.e. lamina, facets, spinous
process) in order to reach the target site (which typically
comprises the disc space). Anterior-access procedures are
relatively simple for surgeons in that they do not involve reducing
or cutting away bony structures to reach the surgical target site.
However, they are nonetheless disadvantageous in that they require
traversing through a much greater distance within the patient to
establish the operative corridor, oftentimes requiring an
additional surgeon to assist with moving the various internal
organs out of the way to create the operative corridor.
[0008] The present invention is directed at eliminating, or at
least minimizing the effects of, the above-identified drawbacks in
the prior art.
SUMMARY
[0009] The present invention accomplishes this goal by providing a
novel access system and related methods which involve: (1)
distracting the tissue between the patient's skin and the surgical
target site to create an area of distraction (otherwise referred to
herein as a "distraction corridor"); (2) retracting the distraction
corridor to establish and maintain an operative corridor; and/or
(3) detecting the existence of (and optionally the distance and/or
direction to) neural structures before, during and after the
establishment of the operative corridor through (or near) any of a
variety of tissues having such neural structures which, if
contacted or impinged, may otherwise result in neural impairment
for the patient.
[0010] As used herein, "distraction" or "distracting" is defined as
the act of creating a corridor (extending to a location at or near
the surgical target site) having a certain cross-sectional area and
shape ("distraction corridor"), and "retraction" or "retracting" is
defined as the act of creating an operative corridor by increasing
the cross-sectional area of the distraction corridor (and/or
modifying its shape) with at least one retractor blade and
thereafter maintaining that increased cross-sectional area and/or
modified shape such that surgical instruments can be passed through
operative corridor to the surgical target site. It is expressly
noted that, although described herein largely in terms of use in
spinal surgery, the access system of the present invention is
suitable for use in any number of additional surgical procedures,
including those wherein tissue having significant neural structures
must be passed through (or near) in order to establish an operative
corridor.
[0011] According to one aspect, the present invention provides a
surgical access system having an initial tissue distraction
assembly and a pivot linkage assembly forming part of a secondary
distraction assembly and a retraction assembly. The secondary
distraction assembly includes first and second distraction arms
forming part of the pivot linkage assembly, first and second
speculum blades extending through receiving passageways formed
within the first and second distraction arms, and a handle assembly
forming part of the pivot linkage. As will be described below, the
distraction arms may be advanced over the initial distraction
assembly such that the speculum blades are passed into the tissue
to be secondarily distracted. Thereafter, the handle assembly may
be activated to perform the necessary distraction. That is, the
handle assembly can be manipulated by a user to move the first and
second distraction arms away from one another, which will at the
same time move the distal ends of the speculum blades to create a
full distraction corridor.
[0012] After the secondary distraction, a pair of retractors blades
may be introduced into the distraction corridor and positioned to
create an operative corridor to the surgical target site. In a
preferred embodiment, retractor blade is introduced first and
positioned such that its distal end is generally located towards
the posterior region of the spinal target site, which forms a
useful barrier to prevent any exiting nerve roots 30 from entering
the surgical target site, as well as to prevent any surgical
instruments from passing outside the surgical target site and into
contact with the exiting nerve roots 30 or other sensitive tissue.
The retractor blade may thereafter be introduced and moved in a
generally anterior direction away from the retractor blade,
effectively creating the operative corridor. The retractor blades
may be locked in relation to the pivot linkage assembly in any
number of suitable fashions, including but not limited to the use
of the nut-bolt assemblies well known in the art. To lock the
retractor blades in relation to the surgical target site, optional
locking members may be advanced through receiving passageways
formed in one or more of the retractor blades such that a distal
region of the locking member is brought into a press-fit, secure
engagement between the adjacent vertebral bodies to thereby
maintain the respective retractor blade in position. With the
operative corridor established, any of a variety of surgical
instruments, devices, or implants may be passed through and/or
manipulated at or near the surgical target site depending upon the
given surgical procedure.
[0013] According to yet another aspect of the present invention,
any number of distraction assemblies and/or retraction assemblies
(including but not limited to those described herein) may be
equipped to detect the presence of (and optionally the distance
and/or direction to) neural structures during the steps tissue
distraction and/or retraction. To accomplish this, one or more
stimulation electrodes are provided on the various components of
the distraction assemblies and/or retraction assemblies, a
stimulation source (e.g. voltage or current) is coupled to the
stimulation electrodes, a stimulation signal is emitted from the
stimulation electrodes as the various components are advanced
towards the surgical target site, and the patient is monitored to
determine if the stimulation signal causes muscles associated with
nerves or neural structures within the tissue to innervate. If the
nerves innervate, this indicates that neural structures may be in
close proximity to the distraction and/or retraction
assemblies.
[0014] This monitoring may be accomplished via any number of
suitable fashions, including but not limited to observing visual
twitches in muscle groups associated with the neural structures
likely to found in the tissue, as well as any number of monitoring
systems. In either situation (traditional EMG or surgeon-driven EMG
monitoring), the access system of the present invention may
advantageously be used to traverse tissue that would ordinarily be
deemed unsafe or undesirable, thereby broadening the number of
manners in which a given surgical target site may be accessed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Many advantages of the present invention will be apparent to
those skilled in the art with a reading of this specification in
conjunction with the attached drawings, wherein like reference
numerals are applied to like elements and wherein:
[0016] FIG. 1 is a perspective view of a surgical access system
according to one aspect of the present invention;
[0017] FIG. 2 is a perspective view of an initial tissue
distraction assembly forming part of a surgical access system
according to the present invention;
[0018] FIGS. 3-4 are exploded views detailing the distal portions
of the initial tissue distraction assembly shown in FIG. 2;
[0019] FIG. 5 is a perspective view of a pivot linkage assembly
equipped with speculum blades according to the present
invention:
[0020] FIG. 6 is a side view of the pivot linkage assembly shown in
FIG. 5;
[0021] FIGS. 7-8 are perspective views showing the pivot linkage
assembly of FIG. 5 in use;
[0022] FIGS. 9-10 are perspective views of a retractor blade
forming part of a surgical access system according to the present
invention:
[0023] FIG. 11 is a perspective view of a locking member for use
with the retractor blade of FIGS. 9-10 according to the present
invention;
[0024] FIG. 12 is a perspective view of an exemplary nerve
monitoring system capable of performing nerve monitoring before,
during and after the creating of an operative corridor to a
surgical target site using the surgical access system in accordance
with the present invention:
[0025] FIG. 13 is a block diagram of the nerve monitoring system
shown in FIG. 12:
[0026] FIGS. 14-15 are screen displays illustrating exemplary
features and information communicated to a user during the use of
the nerve monitoring system of FIG. 12;
[0027] FIGS. 16-33 illustrate the various method steps (some
optional) involved in accessing (by way of example only) a surgical
target site in the spine according to the present invention.
DETAILED DESCRIPTION
[0028] Illustrative embodiments of the invention are described
below. In the interest of clarity, not all features of an actual
implementation are described in this specification. It will of
course be appreciated that in the development of any such actual
embodiment, numerous implementation-specific decisions must be made
to achieve the developers' specific goals, such as compliance with
system-related and business-related constraints, which will vary
from one implementation to another. Moreover, it will be
appreciated that such a development effort might be complex and
time-consuming, but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure. It is furthermore to be readily understood that,
although discussed below primarily within the context of spinal
surgery, the surgical access system of the present invention may be
employed in any number of anatomical settings to provide access to
any number of different surgical target sites throughout the body.
The surgical access system disclosed herein boasts a variety of
inventive features and components that warrant patent protection,
both individually and in combination.
[0029] The present invention is directed at a novel surgical access
system and related methods which involve creating a distraction
corridor to a surgical target site, thereafter retracting the
distraction corridor to establish and maintain an operative
corridor to the surgical target site, and optionally detecting the
existence of (and optionally the distance and/or direction to)
neural structures before, during and/or after the formation of the
distraction and/or operative corridors. The steps of distraction
followed by retraction are advantageous because they provide the
ability to more easily position an operative corridor-establishing
device through tissue that is strong, thick or otherwise
challenging to traverse in order to access a surgical target site.
The various distraction systems of the present invention are
advantageous in that they provide an improved manner of
atraumatically establishing a distraction corridor prior to the use
of the retraction systems of the present invention. The various
retractor systems of the present invention are advantageous in that
they provide an operative corridor having improved cross-sectional
area and shape (including customization thereof) relative to the
prior art surgical access systems. Moreover, by optionally
equipping the various distraction systems and/or retraction systems
with one or more electrodes, an operative corridor may be
established through (or near) any of a variety of tissues having
such neural structures which, if contacted or impinged, may
otherwise result in neural impairment for the patient.
[0030] FIG. 1 illustrates a surgical access system 10 according to
one aspect of the present invention. The surgical access system 10
includes an initial tissue distraction assembly 12 and a pivot
linkage assembly 14 forming part of a secondary distraction
assembly and a retraction assembly. The secondary distraction
assembly includes first and second distraction arms 16, 18 forming
part of the pivot linkage assembly 14, first and second speculum
blades 20, 22 extending through receiving passageways formed within
the first and second distraction arms 16, 18, and a handle assembly
24 forming part of the pivot linkage 14. As will be described
below, the distraction arms 16, 18 may be advanced over the initial
distraction assembly 12 such that the speculum blades 20, 22 are
passed into the tissue to be secondarily distracted. Thereafter,
the handle assembly 24 may be activated to perform the necessary
distraction. That is, the handle assembly 24 can be manipulated by
a user to move the first and second distraction arms 16, 18 away
from one another, which will at the same time move the distal ends
of the speculum blades 20, 22 to create a full distraction
corridor.
[0031] After the secondary distraction, a pair of retractors blades
26, 28 may be introduced into the distraction corridor and
positioned to create an operative corridor to the surgical target
site. In a preferred embodiment, retractor blade 26 is introduced
first and positioned such that its distal end is generally located
towards the posterior region of the spinal target site, which forms
a useful barrier to prevent any exiting nerve roots 30 from
entering the surgical target site, as well as to prevent any
surgical instruments from passing outside the surgical target site
and into contact with the exiting nerve roots 30 or other sensitive
tissue. The retractor blade 28 may thereafter be introduced and
moved in a generally anterior direction away from the retractor
blade 26, effectively creating the operative corridor. The
retractor blades 26, 28 may be locked in relation to the pivot
linkage assembly 14 in any number of suitable fashions, including
but not limited to the use of the nut-bolt assemblies 32, 34 well
known in the art. To lock the retractor blades 26, 28 in relation
to the surgical target site, optional locking members 36 may be
advanced through receiving passageways formed in one or more of the
retractor blades 26, 28 such that a distal region of the locking
member 36 is brought into a press-fit, secure engagement between
the adjacent vertebral bodies to thereby maintain the respective
retractor blade 26, 28 in position. With the operative corridor
established, any of a variety of surgical instruments, devices, or
implants may be passed through and/or manipulated at or near the
surgical target site depending upon the given surgical
procedure.
Distraction
[0032] FIG. 2 illustrates the initial tissue distraction assembly
12, which is designed to perform an initial distraction of tissue
from the skin of the patient down to or near the surgical target
site. The initial tissue distraction assembly 12 may be constructed
from any number of materials suitable for medical applications,
including but not limited to plastics, metals, ceramics or any
combination thereof. Depending on the construction, some or all of
the tissue distraction assembly 12 may be disposable (i.e. single
use) and/or reusable (i.e. multi-use).
[0033] The initial tissue distraction assembly 12 may include any
number of components capable of performing the necessary initial
distraction. By way of example, with combined reference to FIGS.
2-4, this may be accomplished by providing the initial distraction
assembly 12 as including a K-wire 44 and one or more dilators 46,
48. The K-wire 44 is preferably constructed having generally narrow
diameter (such as, by way of example only, 1.5 mm) and sufficient
rigidity and strength such that it can pierce the skin of the
patient and be advanced through the intervening tissue to reach the
surgical target site. The K-wire 44 also preferably includes
indicia for determining the distance between a distal end 50 and
the skin of the patient. The dilators 46, 48 are inner and outer
dilating elements, respectively, capable of being sequentially
introduced over the K-wire 44 for the purpose of further
distracting the tissue previously distracted by the K-wire 44.
[0034] The inner dilator 46 is preferably constructed having an
inner diameter approximating the diameter of the K-wire 44 (such
as, by way of example only, 1.5 mm), an outer diameter of increased
dimension (such as, by way of example only, 6.5 mm), and indicia
for determining the distance between a distal end 52 and the skin
of the patient. The outer dilator 48 is similarly preferably
constructed having an inner diameter approximating the outer
diameter of the inner dilator 46 (such as, by way of example only,
6.5 mm), an outer diameter of increased dimension (such as, by way
of example only, 9 mm), and indicia for determining the distance
between a distal end 54 and the skin of the patient. The respective
lengths of the K-wire 44 and dilators 46, 48 may vary depending
upon the given surgical target site (that is, the "depth" of the
surgical target site within the patient). It will be similarly
appreciated that the diameters and dimensions for these elements
may also vary depending upon the particular surgical procedure. All
such surgically appropriate variations (length, diameter, etc . . .
) are contemplated as falling within the scope of the present
invention. It is further contemplated and within the scope of the
present invention that additional dilators of increasing diameters
may be employed to sequentially dilate to the point where a bladed
retractor or retraction assembly may be employed to thereafter
create an operative corridor according to the present invention
(without the need for secondary distraction as described
below).
[0035] Referring to FIGS. 5-6, the secondary tissue distraction is
preferably performed using the pivot linkage assembly 14 in
conjunction with the first and second distraction arms 16, 18 and
first and second speculum blades 20, 22. The speculum blades 20, 22
extend through receiving passageways 38 (FIG. 6) formed within the
first and second distraction arms 16, 18. The handle assembly 24
includes first and second pivot arms 60, 62 disposed on one end of
the assembly, and third and fourth pivot arms 64, 66 on the
opposite end. First and second pivot arms 60, 62 are pivotably
coupled via a rod 80 forming part of the locking assembly 32 (a
locking nut 82 forms the remainder of the locking assembly 32).
Second and third pivot arms 64, 66 are pivotably coupled via a rod
84 forming part of the locking assembly 34 (a locking nut 86 forms
the remainder of the locking assembly 34).
[0036] First and second linkage assemblies 70, 72 extend between
the distal ends of the pivot arms 60-66, each including a pair of
linkages 74, 76 pivotably coupled together via a rod 78. A rachet
member 68 may be used to maintain the first pivot arms 60 relative
to the second pivot arm 62 as they are separated during use. As the
pivot arms 60, 62 are moved away from one another, the first and
second distraction arms 16, 18 (being coupled to or integrally
formed with the linkages 76 of first and second linkage assemblies
72, 74) will similarly move away from one another. With the
speculum blades 20, 22 disposed within the passageways 38 (FIG. 5),
the relative movement of the pivot arms 16, 18 will cause the
speculum blades 20, 22 to move apart and thus perform the desired
secondary distraction.
[0037] The pivot linkage assembly 14 may be constructed from any
number of materials suitable for medical applications, including
but not limited to plastics, metals, ceramics or any combination
thereof. Depending on the construction, some or all of the pivot
linkage assembly 14 may be disposable (i.e. single use) and/or
reusable (i.e. multi-use).
[0038] The speculum blades 20, 22 are generally elongate in nature
and include a pair of mating grooves 88 formed along the inwardly
facing surfaces of the speculum blades 20, 22 which, when mated
together, form a lumen capable of passing over the K-wire 44. In a
preferred embodiment, the speculum blades 20, 22 are separable from
distraction arms 16, 18 such that the blades 20, 22 can be
introduced into the patient and thereafter engaged with the handle
assembly 24 to effectuate the secondary distraction. As will be
described in greater detail below, this separable construction
allows the speculum blades 20, 22 to be introduced down to the
surgical target site by passing them through the outer dilator 48
and over with the K-wire 44 (the latter by virtue of the lumen
formed by the pair of mating grooves 88 along the inwardly facing
surfaces of the speculum blades 20, 22). This is obviously only
possible by first removing the inner dilator 46 from within the
second dilator 48 while leaving the K-wire 44 in place. Although
shown and described herein as being of separable construction, it
will be appreciated by those skilled in the art that the speculum
blades 20, 22 may be of generally non-separable or fixed
construction with the pivot arms 16, 18 of the handle assembly
24.
Retraction
[0039] The retraction of the present invention is performed by
expanding and/or modifying the distraction corridor to establish
and maintain an operative corridor to the surgical target site. As
shown in FIGS. 7-10, the pivot linkage 14 is configured to receive
(and have coupled thereto) a pair of retractor blades 90, 92 of the
type shown in FIGS. 9-10. The retractor blades 90, 92 include a
main body element 94 extending downwardly and angularly away from a
pair of mounting arms 96, 98. The mounting arms 96, 98 are spaced
apart from one another so as to create a channel 100 dimensioned to
receive the respective rods 80, 84 of the locking assemblies 32,
34. Once positioned within the channel 100, the retractor blades
90, 92 may be locked in a desired position by tightening the
respective nuts 82, 86 of the locking assemblies 32, 34.
[0040] In a preferred embodiment, one or more of the retractor
blades 90, 92 may be equipped with a passageway 102 at or near the
distal end of the main body 94, such as by providing a generally
planar member 104 along the generally curved distal region of the
retractor blade 90, 92. This passageway 102 is dimensioned to
receive a locking member 36 of the type shown in FIG. 11. The
locking member 36 includes a coupling region 106 for engagement
with an introducer tool 112 (FIG. 8), a main body region 108 to be
disposed generally within the passageway 102 in use, and a distal
region 110 to be introduced into the disc space and engaged between
the adjacent vertebral bodies to secure the distal ends of the
retractor blades 90, 92 during use. In addition to securing the
retractor blades 90, 92 relative to the surgical target site, the
distal region 110 also serves to prevent the ingress of unwanted or
sensitive biological structures (e.g., nerve roots and/or
vasculature) into the surgical target site, as well as prevent
instruments from passing outside the surgical target site and
contacting surrounding tissues or structures.
[0041] The retractor blades 90, 92 may also be optionally provided
with at least one guard member 114 extending in a curved fashion
(and/or, although not shown, in a generally straight fashion) from
the distal end of the retractor blade 90, 92. The guard member 114
may be provided, by way of example, for the purpose of preventing
tissue (such as nerve roots in spinal surgery applications) from
entering into the operative corridor during surgery and for
preventing instruments from extending outside the operative
corridor and/or the general vicinity of the surgical target
site.
[0042] The retractor blades 90, 92 may also be equipped with any
number of different mechanisms for transporting or emitting light
at or near the surgical target site to aid the surgeon's ability to
visualize the surgical target site, instruments and/or implants
during the given surgical procedure. For example, one or more
strands of fiber optic cable may be coupled to the retractor blades
90, 92 such that light may be delivered from a light source and
selectively emitted into the operative corridor and/or the surgical
target site. This may be accomplished by constructing the retractor
blades 90, 92 of suitable material (such as clear polycarbonate)
and configuration such that light may be transmitted generally
distally through a light exit region formed along the entire inner
periphery of the retractor blade 90, 92 and located in the general
vicinity as the distal opening of the passageway 102. This may be
performed by providing the retractor blade 90, 92 having
light-transmission characteristics (such as with clear
polycarbonate construction) and transmitting the light almost
entirely within the walls of the retractor blade 90, 92 (such as by
frosting or otherwise rendering opaque portions of the exterior
and/or interior and coupling the light source thereto such as via a
port) until it exits a portion along the interior of the retractor
blades 90, 92 to shine at or near the surgical target site.
[0043] In one embodiment, a variety of sets of retractor blades 90,
92 may be provided, each having a different length to account for
any number of possible surgical target sites. In a further
embodiment, each set of retractor blades 90, 92 may be marked or
color-coded to aid in indicating to the surgeon the particular
length of the blade 90, 92 or the depth of the surgical target
site.
[0044] The retractor blades 90, 92 and the locking member 36 may be
constructed from any number of materials suitable for medical
applications, including but not limited to plastics, metals,
ceramics or any combination thereof. Depending on the construction,
some or all of these devices may be disposable (i.e. single use)
and/or reusable (i.e. multi-use).
[0045] Any number of suitable mounting units (not shown) may be
employed to maintain the pivot linkage assembly 14 in a fixed and
rigid fashion relative to the patient. By way of example only, this
may be accomplished by providing the mounting unit as a generally
U-shaped mounting arm for lockable engagement with the pivot
linkage assembly 14, and a coupling mechanism (not shown) extending
between the mounting arm and a rigid structure (such as the
operating table) for maintaining the U-shaped mounting arm in a
fixed and rigid position.
Nerve Surveillance
[0046] According to yet another aspect of the present invention,
any number of distraction components and/or retraction components
(including but not limited to those described herein) may be
equipped to detect the presence of (and optionally the distance
and/or direction to) neural structures during the steps tissue
distraction and/or retraction. This is accomplished by employing
the following steps: (1) one or more stimulation electrodes are
provided on the various distraction and/or retraction components:
(2) a stimulation source (e.g. voltage or current) is coupled to
the stimulation electrodes: (3) a stimulation signal is emitted
from the stimulation electrodes as the various components are
advanced towards or maintained at or near the surgical target site;
and (4) the patient is monitored to determine if the stimulation
signal causes muscles associated with nerves or neural structures
within the tissue to innervate. If the nerves innervate, this may
indicate that neural structures may be in close proximity to the
distraction and/or retraction components.
[0047] Neural monitoring may be accomplished via any number of
suitable fashions, including but not limited to observing visual
twitches in muscle groups associated with the neural structures
likely to found in the tissue, as well as any number of monitoring
systems, including but not limited to any commercially available
"traditional" electromyography (EMG) system (that is, typically
operated by a neurophysiologist. Such monitoring may also be
carried out via the surgeon-driven EMG monitoring system shown and
described in the following commonly owned and co-pending PCT
Applications (collectively "NeuroVision PCT Applications"): PCT
App. Ser. No. PCT/US02/22247, entitled "System and Methods for
Determining Nerve Proximity, Direction, and Pathology During
Surgery," filed on Jul. 11, 2002; PCT App. Ser. No. PCT/US02/30617,
entitled "System and Methods for Performing Surgical Procedures and
Assessments," filed on Sep. 25, 2002; PCT App. Ser. No.
PCT/US02/35047, entitled "System and Methods for Performing
Percutaneous Pedicle Integrity Assessments," filed on Oct. 30,
2002; and PCT App. Ser. No. PCT/US03/02056, entitled "System and
Methods for Determining Nerve Direction to a Surgical Instrument,"
filed Jan. 15, 2003. The entire contents of each of the
above-enumerated NeuroVision PCT Applications is hereby expressly
incorporated by reference into this disclosure as if set forth
fully herein.
[0048] In any case (visual monitoring, traditional EMG and/or
surgeon-driven EMG monitoring), the access system of the present
invention may advantageously be used to traverse tissue that would
ordinarily be deemed unsafe or undesirable, thereby broadening the
number of manners in which a given surgical target site may be
accessed.
[0049] FIGS. 12-13 illustrate, by way of example only, a monitoring
system 120 of the type disclosed in the NeuroVision PCT
Applications suitable for use with the surgical access system 10 of
the present invention. The monitoring system 120 includes a control
unit 122, a patient module 124, and an EMG harness 126 and return
electrode 128 coupled to the patient module 124, and a cable 132
for establishing electrical communication between the patient
module 124 and the surgical access system 10 (FIG. 1). More
specifically, this electrical communication can be achieved by
providing, by way of example only, a hand-held stimulation
controller 152 capable of selectively providing a stimulation
signal (due to the operation of manually operated buttons on the
hand-held stimulation controller 152) to one or more connectors
156a, 156b, 156c. The connectors 156a, 156b, 156c are suitable to
establish electrical communication between the hand-held
stimulation controller 152 and (by way of example only) the
stimulation electrodes on the K-wire 44, the dilators 46, 46, the
speculum blades 20, 22, the retractor blades 90, 92, and/or the
guard members 114 (collectively "surgical access instruments").
[0050] In order to use the monitoring system 120, then, these
surgical access instruments must be connected to the connectors
156a, 156b and/or 156c, at which point the user may selectively
initiate a stimulation signal (preferably, a current signal) from
the control unit 122 to a particular surgical access instruments.
Stimulating the electrode(s) on these surgical access instruments
before, during and/or after establishing operative corridor will
cause nerves that come into close or relative proximity to the
surgical access instruments to depolarize, producing a response in
a myotome associated with the innervated nerve.
[0051] The control unit 122 includes a touch screen display 140 and
a base 142, which collectively contain the essential processing
capabilities (software and/or hardware) for controlling the
monitoring system 120. The control unit 122 may include an audio
unit 118 that emits sounds according to a location of a surgical
element with respect to a nerve. The patient module 124 is
connected to the control unit 122 via a data cable 144, which
establishes the electrical connections and communications (digital
and/or analog) between the control unit 122 and patient module 124.
The main functions of the control unit 122 include receiving user
commands via the touch screen display 140, activating stimulation
electrodes on the surgical access instruments, processing signal
data according to defined algorithms, displaying received
parameters and processed data, and monitoring system status and
report fault conditions. The touch screen display 140 is preferably
equipped with a graphical user interface (GUI) capable of
communicating information to the user and receiving instructions
from the user. The display 140 and/or base 142 may contain patient
module interface circuitry (hardware and/or software) that commands
the stimulation sources, receives digitized signals and other
information from the patient module 124, processes the EMG
responses to extract characteristic information for each muscle
group, and displays the processed data to the operator via the
display 140.
[0052] In one embodiment, the monitoring system 120 is capable of
determining nerve direction relative to one or more of the K-wire
44, dilation cannula 46, 48, speculum blades 20, 22, the retractor
blades 90, 92, and/or the guard members 114 before, during and/or
following the creation of an operative corridor to a surgical
target site. Monitoring system 120 accomplishes this by having the
control unit 122 and patient module 124 cooperate to send
electrical stimulation signals to one or more of the stimulation
electrodes provided on these instruments. Depending upon the
location of the surgical access system 10 within a patient (and
more particularly, to any neural structures), the stimulation
signals may cause nerves adjacent to or in the general proximity of
the surgical access system 10 to depolarize. This causes muscle
groups to innervate and generate EMG responses, which can be sensed
via the EMG harness 126. The nerve direction feature of the system
120 is based on assessing the evoked response of the various muscle
myotomes monitored by the system 120 via the EMG harness 126.
[0053] By monitoring the myotomes associated with the nerves (via
the EMG harness 126 and recording electrode 127) and assessing the
resulting EMG responses (via the control unit 122), the surgical
access system 10 is capable of detecting the presence of (and
optionally the distant and/or direction to) such nerves. This
provides the ability to actively negotiate around or past such
nerves to safely and reproducibly form the operative corridor to a
particular surgical target site, as well as monitor to ensure that
no neural structures migrate into contact with the surgical access
system 10 after the operative corridor has been established. In
spinal surgery, for example, this is particularly advantageous in
that the surgical access system 10 may be particularly suited for
establishing an operative corridor to an intervertebral target site
in a postero-lateral, trans-psoas fashion so as to avoid the bony
posterior elements of the spinal column.
[0054] FIGS. 14-15 are exemplary screen displays (to be shown on
the display 140) illustrating one embodiment of the nerve direction
feature of the monitoring system shown and described with reference
to FIGS. 12-13. These screen displays are intended to communicate a
variety of information to the surgeon in an easy-to-interpret
fashion. This information may include, but is not necessarily
limited to, a display of the function 180 (in this case
"DIRECTION"), a graphical representation of a patient 181, the
myotome levels being monitored 182, the nerve or group associated
with a displayed myotome 183, the name of the instrument being used
184 (in this case, a dilator 46, 48), the size of the instrument
being used 185, the stimulation threshold current 186, a graphical
representation of the instrument being used 187 (in this case, a
cross-sectional view of a dilator 46, 48) to provide a reference
point from which to illustrate relative direction of the instrument
to the nerve, the stimulation current being applied to the
stimulation electrodes 188, instructions for the user 189 (in this
case, "ADVANCE" and/or "HOLD"), and (in FIG. 15) an arrow 190
indicating the direction from the instrument to a nerve. This
information may be communicated in any number of suitable fashions,
including but not limited to the use of visual indicia (such as
alpha-numeric characters, light-emitting elements, and/or graphics)
and audio communications (such as a speaker element). Although
shown with specific reference to a dilating cannula (such as at
184), it is to be readily appreciated that the present invention is
deemed to include providing similar information on the display 140
during the use of any or all of the various instruments forming the
surgical access system 10 of the present invention, including the
initial distraction assembly 12 (i.e. the K-wire 44 and dilators
46, 48), the speculum blades 20, 22 and/or the retractor blades 90,
92 and/or the guard members 114.
[0055] The initial distraction assembly 12 (FIGS. 2-4) may be
provided with one or more electrodes for use in providing the
neural monitoring capabilities of the present invention. By way of
example only, the K-wire 44 may be equipped with a distal electrode
200. This may be accomplished by constructing the K-wire 44 for a
conductive material, providing outer layer of insulation 202
extending along the entire length with the exception of an exposure
that defines the electrode 200. As best shown in FIGS. 3-4, the
electrode 200 has an angled configuration relative to the rest of
the K-wire 44 (such as, by way of example only, in the range of
between 15 and 75 degrees from the longitudinal axis of the K-wire
44). The angled nature of the electrode 200 is advantageous in that
it aids in piercing tissue as the K-wire 44 is advanced towards the
surgical target site.
[0056] The angled nature of the distal electrode 200 is also
important in that it provides the ability to determine the location
of nerves or neural structures relative to the K-wire 44 as it is
advanced towards or resting at or near the surgical target site.
This "directional" capability is achieved by the fact that the
angled nature of the electrode 200 causes the electrical
stimulation to be projected away from the distal portion of the
K-wire 44 in a focused, or directed fashion. The end result is that
nerves or neural structures which are generally closer to the side
of the K-wire 44 on which the electrode 200 is disposed will have a
higher likelihood of firing or being innervated that nerves or
neural structures on the opposite side as the electrode 200.
[0057] The direction to such nerves or neural structures may thus
be determined by physically rotating the K-wire 44 at a particular
point within the patient's tissue and monitoring to see if any
neural stimulation occurs at a given point within the rotation.
Such monitoring can be performed via visual observation, a
traditional EMG monitoring, as well as the nerve surveillance
system disclosed in the above-referenced NeuroVision PCT
Applications. If the signals appear more profound or significant at
a given point within the rotation, the surgeon will be able tell
where the corresponding nerves or neural structures are, by way of
example only, by looking at reference information (such as the
indicia) on the exposed part of the K-wire 44 (which reference
point is preferably set forth in the exact same orientation as the
electrode 200).
[0058] Dilators 46, 48 may also be provided with angled electrodes
204, 206, respectively, for the purpose of determining the location
of nerves or neural structures relative to the dilators 46, 48 as
they are advanced over the K-wire 44 towards or positioned at or
near the surgical target site. Due to this similarity in function
with the electrode 200 of the K-wire 44, a repeat explanation is
not deemed necessary. The dilators 46, 48 may be equipped with the
electrodes 204, 206 via any number of suitable methods, including
but not limited to providing electrically conductive elements
within the walls of the dilators 46, 48, such as by manufacturing
the dilators 46, 48 from plastic or similar material capable of
injection molding or manufacturing the dilators 46, 48 from
aluminum (or similar metallic substance) and providing outer
insulation layer with exposed regions (such as by anodizing the
exterior of the aluminum dilator).
[0059] According to one aspect of the present invention, additional
neural monitoring equipment may be employed so as to further
prevent inadvertent contact with neural structures. For example,
after the initial dilator 46 has been withdrawn in order to
subsequently receive the mated speculum blades 20, 22, a
confirmation probe (providing a stimulation signal) may be inserted
through the outer dilator 48 and to a point at or near the surgical
target site. The confirmation probe may thereafter be stimulated
for the purpose of double-checking to ensure that no nerves or
neural structures are disposed in the tissue near (or have migrated
into the vicinity of) the distal end 54 of the outer dilator 48
before introducing the speculum blades 20, 22. By confirming in
this fashion, the outer dilator 48 may be removed following the
introduction of the speculum blades 20, 22 and the secondary
distraction performed (by coupling the handle assembly 24 to the
blades 20, 22 and expanding) without fear of inadvertently causing
the speculum blades 20, 22 to contact nerves or neural
structures.
[0060] The secondary distraction of the present invention (FIGS.
5-6) may be provided with one or more electrodes for use in
providing the neural monitoring capabilities of the present
invention. By way of example only, it may be advantageous to
provide one or more electrodes along the speculum blades 20, 22
and/or on the concave region 252 (such as stimulation electrode
208) for the purpose of conducting neural monitoring before, during
and/or after the secondary distraction.
[0061] The retractor blades 90, 92 of the present invention (FIGS.
7-10) may also be provided with one or more electrodes for use in
providing the neural monitoring capabilities of the present
invention. By way of example only, it may be advantageous to
provide one or more electrodes 210 on the guard members 114 and/or
the stimulation electrodes 212 on the locking members 36
(preferably on the side facing away from the surgical target site)
for the purpose of conducting neural monitoring before, during
and/or after the retractor blades 90, 92 have been positioned at or
near the surgical target site.
[0062] The surgical access system 10 of the present invention may
be sold or distributed to end users in any number of suitable kits
or packages (sterile and/or non-sterile) containing some or all of
the various components described herein. For example, the pivot
linkage assembly 14 may be provided such that the pivot arms 16, 18
and speculum blades 20, 22 are disposable and the retractor blades
90, 92 are reusable. In a further embodiment, an initial kit may
include these materials, including a variety of sets of retractor
blades 90, 92 having varying (or "incremental") lengths to account
for surgical target sites of varying locations within the
patient.
Spine Surgery Example
[0063] The surgical access system 10 of the present invention will
now be described, by way of example, with reference to the spinal
application shown in FIGS. 16-33. It will, of course, be
appreciated that the surgical access system and related methods of
the present invention may find applicability in any of a variety of
surgical and/or medical applications such that the following
description relative to the spine is not to be limiting of the
overall scope of the present invention. More specifically, while
described below employing the nerve monitoring features described
above (otherwise referred to as "nerve surveillance") during spinal
surgery, it will be appreciated that such nerve surveillance will
not be required in all situations, depending upon the particular
surgical target site.
[0064] FIGS. 16-22 illustrate the method steps involved in using
the initial tissue distraction assembly 12 of the present
invention. The K-wire 44 is first introduced along a given pathway
towards the surgical target site (which, in this case, is an
intervertebral disc level of the lumbar spine). Determining the
preferred angle of incidence into the surgical target site (as well
as the advancement or positioning of any required surgical
instruments (such as the surgical access system of the present
invention), devices and/or implants) may be facilitated through the
use of surgical imaging systems (such as fluoroscopy) as well any
number of stereotactic guide systems, including but not limited to
those shown and described in co-pending and commonly owned US
patent application Ser. No. 09/888,223, filed Jun. 22, 2001 and
entitled "Polar Coordinate Surgical Guideframe," the entire
contents of which is incorporated by reference as if set forth in
its entirety herein.
[0065] Nerve surveillance is preferably conducted during this step
(via electrode 200) to monitor for the existence of (and optionally
the distance and direction to) nerves or neural structures in the
tissue through which the K-wire 44 must pass to reach the surgical
target site. According to a preferred embodiment of the present
invention, it is generally desired to advance the K-wire 44 such
the distal electrode 200 is disposed a distance anterior to the
exiting nerve root 300 (such as, by way of example, 10 mm). As
shown in FIGS. 16-17, it is preferred to advance the K-wire 44 to
the annulus 302 of the disc before advancing the inner dilator 46.
This is to prevent the unnecessary distraction of the psoas muscle
304 (which must be passed through in order to approach the surgical
target site in the lateral or far-lateral approach shown) in the
instance significant nerves or neural structures are encountered in
the initial advancement of the K-wire 44. If such nerves or neural
structures are encountered, the K-wire 44 may simply be removed and
re-advanced along a different approach path.
[0066] As shown in FIGS. 18-19, once the K-wire 44 is safely
introduced to the surgical target site, the inner dilator 46 may
thereafter be advanced over the K-wire 44 until the distal end 52
abuts the annulus 302 of the disc. Nerve surveillance is also
conducted during this step (via electrode 204 shown in FIGS. 3-4)
to monitor for the existence of (and optionally the distance and
direction to) nerves or neural structures in the tissue through
which the inner dilator 46 must pass to reach the surgical target
site. Next, as shown in FIG. 22, the K-wire 44 may be advanced
through the annulus 302 such that the electrode 200 is disposed
within the interior (nucleus pulposis region) of the disc (such as,
by way of example, an internal distance of 15 to 20 mm).
[0067] With reference to FIGS. 21-22, the outer dilator 48 is next
advanced over the inner dilator 46 to further distract the tissue
leading down to the surgical target site. As with the K-wire 44 and
inner dilator 46, nerve surveillance is conducted during this step
(via electrode 206 shown in FIGS. 3-4) to monitor for the existence
of (and optionally the distance and direction to) nerves or neural
structures in the tissue through which the outer dilator 48 must
pass to reach the surgical target site. With reference to FIG. 23,
the inner dilator 48 is next removed, leaving the K-wire 44 and
outer dilator 48 in position. This creates a space therebetween
which, in one embodiment of the present invention, is dimensioned
to receive the speculum blades 20, 22 as shown in FIGS. 24-25. To
accomplish this step, the speculum blades 20, 22 must be disposed
in an abutting relationship so as to form an inner lumen (via
corresponding grooves 88 shown in FIG. 5) dimensioned to be
slideably advancing over the stationary K-wire 44. Once again, as
noted above, it may be desired at this step to advance a
confirmation probe down the outer dilator 48 to interrogate the
tissue surrounding the surgical target site to ensure that no
nerves or neural structures are present in (or have migrated into)
this vicinity before the speculum blades 20, 22 are advanced into
the outer dilator 48.
[0068] Turning to FIGS. 26-27, the outer dilator 48 may then be
removed, leaving the speculum blades 20, 22 in abutting
relationship within the tissue previously distracted by the outer
dilator 48. As shown in FIGS. 28-29, the pivot linkage assembly 14
may be advanced such that the pivot arms 16, 18 slideably (or
otherwise) pass over the speculum blades 20, 22. In one embodiment,
the pivot arms 16, 18 are dimensioned such that each distal end
comes into general abutment with the exterior of the psoas muscle
304. That said, it is within the scope of the invention to provide
the pivot arms 16, 18 such that each distal end extends downward
into the psoas 304 towards the surgical target site (which may be
advantageous from the standpoint of adding rigidity to the distal
portions of the speculum blades 20, 22 for the purpose of
facilitating the process of secondary tissue distraction). Once
positioned over the speculum blades 20, 22, the handle assembly 24
may be operate to distract tissue from the position shown in FIG.
28 to that shown in FIG. 29.
[0069] As shown in FIG. 30, the first retractor 90 is then
introduced into the distracted region, positioned adjacent to the
posterior region of the disc space, and locked to the pivot linkage
14 via the locking assembly 32. At that point, the locking member
36 may be advanced via the tool 112 and engaged with the retractor
blade 90 such that the middle region 108 resides at least partially
within the passageway 102 and the distal region 110 extends into
the disc space. Thereafter, as shown in FIG. 31, the retractor
blade 92 may be introduced into the distracted region, positioned
adjacent to the anterior region of the disc space, and locked to
the pivot linkage 14 via the locking assembly 34. At that point,
another locking member 36 may be engaged in the same fashion as
with the retractor blade 90, with the distal region 110 extending
into the disc space. As shown in FIG. 32, additional retractor
blades 91, 93 may be coupled to the pivot linkage 14 to provide
retraction in the caudal and cephalad directions, respectively.
[0070] The end result is shown in FIG. 33, wherein an operative
corridor has been created to the spinal target site (in this case,
the disc space) defined by the retractor blades 90, 92 (and
optionally 91, 93). The distal regions 110 of the locking each
locking member 36 advantageously extends into the disc space to
prevent the ingress of tissue (e.g., neural, vasculature, etc . . .
) into the surgical target site and/or operative corridor and the
egress of instruments or implants out of the surgical target site
and/or operative corridor.
[0071] In a further protective measure, each retractor blade 90, 92
is equipped with a guard member 114 to prevent similar ingress and
egress. Both guard members 114 (as well as additional regions of
the distal region 110 of the locking member 36) may be provided
with electrodes 210, 212, respectively, capable of performing nerve
surveillance to monitor for the existence of (and optionally the
distance and direction to) nerves or neural structures in the
tissue or region surrounding or adjacent to these components while
disposed in the general vicinity of the surgical target site. The
electrode 210 on the guard member 114 of the posterior retractor
blade 90, in particular, may be used to assess the status or health
of the nerve root 300, especially if the nerve root 300 is in close
proximity to that guard member 114. This may be performed by using
the nerve status determination systems or techniques disclosed in
co-pending and commonly assigned U.S. Pat. No. 6,500,128, entitled
"Nerve Proximity and Status Detection System and Method," the
entire contents of which is hereby incorporated by reference as is
set forth fully herein.
[0072] As evident from the above discussion and drawings, the
present invention accomplishes the goal of providing a novel
surgical access system and related methods which involve creating a
distraction corridor to a surgical target site, thereafter
retracting the distraction corridor to establish and maintain an
operative corridor to the surgical target site, and optionally
detecting the existence of (and optionally the distance and/or
direction to) neural structures before, during and/or after the
formation of the distraction and/or operative corridors.
[0073] The steps of distraction followed by retraction are
advantageous because they provide the ability to more easily
position an operative corridor-establishing device through tissue
that is strong, thick or otherwise challenging to traverse in order
to access a surgical target site. The various distraction systems
of the present invention are advantageous in that they provide an
improved manner of atraumatically establishing a distraction
corridor prior to the use of the retraction systems of the present
invention. The various retractor systems of the present invention
are advantageous in that they provide an operative corridor having
improved cross-sectional area and shape (including customization
thereof) relative to the prior art surgical access systems.
Moreover, by optionally equipping the various distraction systems
and/or retraction systems with one or more electrodes, an operative
corridor may be established through (or near) any of a variety of
tissues having such neural structures which, if contacted or
impinged, may otherwise result in neural impairment for the
patient.
[0074] The surgical access system of the present invention can be
used in any of a wide variety of surgical or medical applications,
above and beyond the spinal applications discussed herein. By way
of example only, in spinal applications, any number of implants
and/or instruments may be introduced through the working cannula
50, including but not limited to spinal fusion constructs (such as
allograft implants, ceramic implants, cages, mesh, etc.), fixation
devices (such as pedicle and/or facet screws and related tension
bands or rod systems), and any number of motion-preserving devices
(including but not limited to nucleus replacement and/or total disc
replacement systems).
[0075] While certain embodiments have been described, it will be
appreciated by those skilled in the art that variations may be
accomplished in view of these teachings without deviating from the
spirit or scope of the present application. For example, with
regard to the monitoring system 120, it may be implemented using
any combination of computer programming software, firmware or
hardware. As a preparatory act to practicing the system 120 or
constructing an apparatus according to the application, the
computer programming code (whether software or firmware) according
to the application will typically be stored in one or more machine
readable storage mediums such as fixed (hard) drives, diskettes,
optical disks, magnetic tape, semiconductor memories such as ROMs
PROMs, etc., thereby making an article of manufacture in accordance
with the application. The article of manufacture containing the
computer programming code may be used by either executing the code
directly from the storage device, by copying the code from the
storage device into another storage device such as a hard disk,
RAM, etc. or by transmitting the code on a network for remote
execution. As can be envisioned by one of skill in the art, many
different combinations of the above may be used and accordingly the
present application is not limited by the scope of the appended
claims.
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