U.S. patent application number 09/966394 was filed with the patent office on 2002-01-31 for surgical retractor and related surgical approach to access the anterior lumbar region.
Invention is credited to Brau, Salvador A..
Application Number | 20020013514 09/966394 |
Document ID | / |
Family ID | 46278244 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020013514 |
Kind Code |
A1 |
Brau, Salvador A. |
January 31, 2002 |
Surgical retractor and related surgical approach to access the
anterior lumbar region
Abstract
An instrument and method for exposing a selected area of the
anterior lumbar region for a surgical procedure on the spine
comprising making an incision on a human or animal body that
exposes the anterior rectus sheath of the left rectus muscle,
cutting the anterior rectus sheath to expose the body of the rectus
muscle, and mobilizing the rectus muscle along its length by at
least 3 cm in both directions from the site of the sheath incision.
The rectus is then retracted medially, and the posterior rectus
sheath is incised to expose the peritoneum. The peritoneum is
pushed aside and tissues between the surgeon and the psoas muscle
are dissected away. The ureter and the left iliac vessels are
mobilized so that they are retractable from the dissected field,
then the rectus muscle is moved laterally and a retractor is
inserted into the dissected field. The retractor comprises a handle
portion and an elongated blade portion having a first end connected
to the handle portion, and having a substantially flat
configuration which generally extends at an angle relative to the
handle and below an axis aligned with the handle when the retractor
is in use in surgery. The blade portion also has a second end
spaced from the handle portion and shaped as a lip which curves in
a direction away from the handle portion. The lip projects to a
remote end spaced less than about 2 cm from a plane defined by the
blade portion adjacent to the lip. The retractor is stabilized by
engaging the lateral aspect of a vertebral body or disc with the
lip of the retractor and retracting the tissues with the blade
portion to expose the selected vertebral area.
Inventors: |
Brau, Salvador A.; (Los
Angeles, CA) |
Correspondence
Address: |
CHRISTIE, PARKER & HALE, LLP
P.O. BOX 7068
PASADENA
CA
91109-7068
US
|
Family ID: |
46278244 |
Appl. No.: |
09/966394 |
Filed: |
September 28, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09966394 |
Sep 28, 2001 |
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09549973 |
Apr 14, 2000 |
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6296609 |
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Current U.S.
Class: |
600/213 ;
600/210 |
Current CPC
Class: |
A61B 17/02 20130101 |
Class at
Publication: |
600/213 ;
600/210 |
International
Class: |
A61B 017/02 |
Claims
1. A retractor instrument for maintaining a clear surgical field,
the instrument comprising: a handle portion; and an elongated blade
portion having a length, and having a first end connected to the
handle portion, in which essentially the entire length of the blade
portion extends from the first end in a direction below an axis
aligned with the handle and extends generally at an angle relative
to the handle portion when the instrument is in an operable
configuration, the blade portion having a second end region
comprising about 10% or less of the length of the blade and spaced
from the handle portion, the second end region shaped as a lip that
curves in a direction away from the handle portion when the blade
portion is in the operable configuration, wherein the lip projects
to a leading edge spaced less than about 2 cm from a plane defined
by the blade portion immediately adjacent to the curvature of the
lip; and wherein the lip has a has a width of at least about 1.75
cm.
2. The retractor of claim 1 wherein the blade portion is
substantially flat.
3. The retractor of claim 1 wherein the blade portion and the
handle portion are set at about a right angle with respect to each
other.
4. The retractor of claim 1 wherein the handle is capable of being
reversibly immobilized by an adaptor to a retractor ring or
arm.
5. The retractor of claim 1 wherein the lip is at least about 0.3
cm long and curves at least about 0.15 cm from the plane of the
blade.
6. The retractor of claim 1 wherein the blade is between about 2.5
and about 10 cm wide, and between about 2 and about 25 cm long.
7. The retractor of claim 6 wherein the blade is between about 2.0
and about 5 cm wide.
8. The retractor of claim 1 wherein the handle and the blade are
formed as a single piece.
9. The retractor of claim 1 wherein the blade portion is formed of
a malleable material that can be manually shaped.
10. The retractor of claim 1 wherein the leading edge of the lip is
roughened.
11. The retractor of claim 1 wherein the lip has a radius of
curvature of between about 1 cm and about 3 cm and the curve
extends between about 20.degree. and about 50.degree. of a circle
of curvature.
12. The retractor of claim 1 in which the second end region of the
blade is rounded along its distal end and defines a continuous
outer edge extending from one side edge of the blade, around the
distal end of the lip, to the opposite side edge of the blade.
13. The retractor of claim 12 in which the lip is at least about
0.3 cm long and curves at least about 0.15 cm from the plane of the
blade.
14. A retractor instrument for maintaining a clear surgical field
for access to an anterior vertebral region of a body, the
instrument comprising: a handle portion; and an elongated blade
portion having a first end connected to the handle portion, the
blade portion extending generally at an angle relative to the
handle portion when the retractor is in an operable configuration,
the blade portion having a second end region spaced from the handle
portion and shaped as a lip which curves in a direction away from
the handle portion, wherein the lip projects to a leading edge
spaced a sufficient distance from a portion of the blade
immediately adjacent the curvature of the lip and configured so
that the curved lip can engage a lateral aspect of a vertebral body
or vertebral disc when the blade portion is positioned adjacent to
and substantially perpendicular to the vertebra; wherein the lip
has a width of at least about 1.75 cm, and wherein the lip has a
surface facing the direction opposite the handle, and the surface
of the lip is roughened.
15. The retractor of claim 14 wherein the blade portion is
substantially flat.
16. The retractor of claim 14 in which the blade portion has a
length sufficient to reach the vertebral region from the anterior
side of the body.
17. The retractor of claim 14 in which the second end region of the
blade is rounded along its distal end and defines a continuous
outer edge extending from one side edge of the blade, around the
distal end of the lip, to the opposite side edge of the blade.
18. A method of clearing an anterior lumbar region surgical field
comprising: making an incision on a body needing surgery that
exposes the anterior rectus sheath of the left rectus muscle;
cutting the anterior rectus sheath to expose the body of the rectus
muscle; mobilizing the rectus muscle along its length by at least 3
cm in both directions from the site of the sheath incision, and
retracting the rectus medially; cutting the posterior rectus sheath
to expose the peritoneum; and dissecting away any intervening
tissues to expose the spine.
19. The method of claim 20 further comprising pushing aside the
peritoneum without damaging it.
20. The method of claim 20 wherein the dissection exposes the psoas
muscle, the method further comprising mobilizing the ureter and the
left iliac vessels so that they are retractable from the dissection
field.
21. A method of exposing a selected area of the anterior lumbar
region for a surgical procedure on that region, the method
comprising: making an incision on a body in a location selected to
expose the selected lumbar region, the incision exposing the
anterior rectus sheath of the left rectus muscle; incising the
anterior rectus sheath to expose the body of the rectus muscle;
mobilizing the rectus muscle along its length by at least 3 cm in
both directions from the site of the sheath incision, and
retracting the rectus medially; incising the posterior rectus
sheath to expose the peritoneum; retracting the rectus muscle
laterally; inserting a retractor into the dissected field, the
retractor comprising a handle portion and an elongated blade
portion having a first end connected to the handle portion, the
blade portion having a substantially flat configuration which
generally extends at an angle relative to the handle, the blade
portion having a second end spaced from the handle portion and
shaped as a lip which curves in a direction away from the handle
portion; and stabilizing the retractor by engaging the lateral
aspect of a vertebral body or disc with the lip of the retractor
and retracting the tissues with the blade portion to expose the
selected vertebral area.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a continuation-in-part of Application No. 09/549,973
filed Apr. 14, 2000, now U.S. Pat. No. 6,296,609, issuing on Oct.
2, 2001, incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to a surgical retractor instrument
for use in maintaining a clear surgical field for access to the
anterior vertebral region of the body.
BACKGROUND OF THE INVENTION
[0003] Spine surgery, such as vertebral fusions, is common and is
becoming more reliable as better methods are developed for
stabilizing the back and improving bone grafts, for example, to
repair disc injuries, vertebral fractures, and the effects of
osteoarthritis. Many spine surgeries require an anterior approach,
such as those for degenerative disc disease (both de novo and to
correct failed prior back surgery), for infected discs, tumor
removal and scoliosis (e.g., for excision, drainage, or
decompression).
[0004] Anterior fusions are often preferable to posterior fusions
because the bone surface area available for the fusion is
considerably larger and any discs to be removed are more
accessible. This makes the likelihood of successful fusion greater
and the time required for the operation less, translating to less
time that the patient is under general anesthesia. For example,
since the introduction of threaded devices for Anterior Lumbar
Interbody Fusion (ALIF), this procedure has become quite popular in
the treatment of degenerative disc disease and chronic spinal
instability as well as in failed posterior arthrodesis attempts.
The procedure, however, is heavily dependent on the ability of the
approach surgeon to provide exposure quickly and safely in view of
a reported incidence of vascular injury as high as 15% (Baker et
al., Spine 1993; 18:2227-2230) and a 2.3% incidence of retrograde
ejaculation (Regan et al., Spine 1999; 24:402-11). The requirement
of a direct anterior-posterior exposure for alignment of the
devices has presented a significant challenge to provide a small
incision and yet maintain the degree of safety necessary to prevent
injury to the iliac vessels and the autonomic nerve plexus.
[0005] Generally, there are two anterior approaches for clearing a
surgical field for the anterior lumbar region currently in use. One
is the paramedian rectus splitting anterior retroperitoneal
approach and the other is the lateral muscle splitting
retroperitoneal approach. Both of these approaches have the
disadvantage that they damage the muscles through which the surgeon
must go to access the retroperitoneal space. Damaged muscle can
lead to increased analgesic requirements during recovery, hernias,
and loss of muscle function in the patient. Additionally, these
approaches may require a large incision, leading to increased
trauma to the skin, abdominal muscles, and internal structures.
This can increase the subsequent pain for the patient, which
requires additional post-operative management, while increasing
recovery time. Procedures that entail or result in penetration of
the peritoneum also lead to increased risk to the patient, for
example, through damage to peritoneal organs, subsequent adhesions,
infection, and the like.
[0006] Likewise, many surgical instruments are used once the field
has been cleared to allow the spine surgeon access to the lumbar
region. Retractors are used to secure the area open during the
spine surgery. A variety of retractors and blades, and other
implements such as Steinman pins, have been used for this purpose
(see, e.g., U.S. Pat. Nos. 3,998,217, 4,813,401, 5,025,780,
5,052,373, 5,688,223, 5,728,046, 5,795,291, 5,902,233, 5,944,658).
While these retractors and implements help keep the area open and
the tissue retracted, they suffer from several disadvantages. For
example, standard retractor blades can slip out of place, or allow
the peritoneum, peritoneal contents, nerves, vessels, or ureter to
escape into the field of the surgery, risking injury to these
structures. Hand-held retractors increase this risk. Pins are
sometimes inserted into the vertebral body to hold back vessels and
nerves, but they carry a great risk during deployment of the very
damage the surgeon seeks to prevent. In lumbar region spine
surgery, vascular injury, often perforation of the iliac vein
and/or artery is the most common and severe complication. Other
issues with the surgical instruments commonly used includes the
size of the retractors, which may require a large incision in order
to be placed correctly and to allow the spine surgeon a large
enough field in which to work.
[0007] A published article entitled "A Simple Retractor for Spinal
Surgery" by G. Mosser Taylor, M.D., describes a retractor designed
for use for posterior spinal surgery. However, use of a Taylor-type
retractor could lead to potential damage to the neural and vascular
structures that are being retracted in the case of anterior lumbar
surgery. The tip of the retractor described by Taylor is too
narrow, too tapered, too thin, and too long to be useful in
anterior spinal surgery without the risk that the narrow relatively
sharp tip would injure large vessels or nerves while being
deployed.
[0008] U.S. Pat. No. 6,152,874 to Looney et al. describes a
retractor used for coronary artery bypass surgery, but the design
of this instrument would not be suitable for anterior lumbar
surgery.
[0009] U.S. Pat. 5,971,920 to Nagel describes a retractor having
spikes that turn inward which could prove dangerous when working
near the Iliac arteries, the Iliac vein, and the sympathetic chain
of nerves that run along the anterio-lateral border of the lumbar
spine. Surfaces such as the spikes on the Nagel retractor are not
used when working near these vital structures because damage of
these structures can be life threatening.
[0010] Thus, a need exists for an instrument and anterior
retroperitoneal approach that permits rapid surgical access to the
desired lumbar area, permits a small incision, and is stable and
safe during subsequent procedures.
SUMMARY OF THE INVENTION
[0011] The present invention provides a retractor blade and
surgical access method that fulfill the need for rapid lumbar
access, a small incision, and reduced risk of bleeding/accidental
vascular injury, nerve injury, or ureter injury. The invention also
provides a secure and stable open position even during bone
routing, drilling, and screwing.
[0012] The invention features a retractor instrument for
maintaining a clear surgical field for access to the anterior
vertebrae region of the body. The retractor instrument comprises a
handle portion and an elongated blade portion having a first end
connected to the handle portion and a second end region spaced from
the handle portion and shaped as a lip that curves in a direction
away from the handle portion when the blade portion is in the
operable configuration. The blade portion extends substantially
along its entire length below an axis aligned with the handle and
generally at an angle relative to the handle portion when the
instrument is in an operable configuration. The lip portion of the
blade takes up no more than about 20% of the blade length,
preferably no more than about 15%, and most preferably no more than
about 10%. The lip projects to a leading edge spaced less than
about 2 cm from a plane defined by the blade portion immediately
adjacent to the curvature of the lip. The lip has a width of at
least about 1.75 cm., although in another embodiment the lip has a
width of at least about 2 cm. The lip is of a shape and size
sufficient to engage the lateral aspect of a vertebral body or
vertebral disc when the blade portion is positioned adjacent to and
substantially perpendicular to the vertebra and/or a disc. The lip
of the blade has the advantage that it can securely engage the
lateral aspect of a vertebral body, something that retractors not
having this lip cannot do, and this secure engagement offers
greatly improved retraction without tissue slipping into the
surgical field. The lip also eliminates the need to have channels
on the blade used to introduce sharp pins to secure the blade to
the vertebral body. Those pins can actually cause damage if not
secured properly.
[0013] They also require wider exposure for proper placement and
fail to provide lateral exposure for protection against vessel
damage. Likewise, the lip itself does not have any sharp
protrusions, which could cause tissue damage.
[0014] The blade of the retractor is preferably substantially flat
in a rigid embodiment, or can be somewhat curved in a malleable
embodiment, and the blade is preferably at an angle from about
80.degree. to 150.degree. to the handle when the retractor is in
use. The angle is measured below an axis aligned with the handle.
In one embodiment, the lip at the distal end of the blade is at
least 0.5 cm long and curves at least about 0.15 cm from the plane
of the blade, and is preferably roughened. Preferably, the lip has
a radius of curvature of between about 1 cm and 3 cm and the curve
of the lip extends between about 20.degree. and 50.degree. of the
circle of curvature. The length of the blade portion is sufficient
to reach the vertebral region from the anterior side of the body it
is being used on. The width of the blade is preferably between
about 0.5-2.5 inches, more preferably between about 1-2 inches, and
most preferably between about 1 to about 1.5 inches. The width of
the blade is important to protect against vessel damage, as in
typical lumbar exposures, the space between the major vessels and
the vertebral body is very limited and to use retractors with
widths over about 2 inches risks stretching or otherwise damaging
the vessels.
[0015] The invention also features a method of clearing an anterior
lumbar region surgical field comprising making an incision on a
body needing surgery that exposes the anterior rectus sheath of the
left rectus muscle; cutting the anterior rectus sheath to expose
the body of the rectus muscle; mobilizing the rectus muscle along
its length by at least 3 cm in both directions from the site of the
sheath incision, and retracting the rectus medially; cutting the
posterior rectus sheath to expose the peritoneum; pushing aside the
peritoneum and dissecting away any intervening tissues to expose
the psoas muscle; mobilizing the ureter and the left iliac vessels
so that they are retractable from the dissection field; and
retracting the rectus muscle laterally, the peritoneum, ureter,
vessels, and intervening tissues to provide a clear anterior lumbar
region surgical field. This surgical procedure has the advantage
that it does not damage the rectus muscle, nor does it perforate
the peritoneum, so recovery for the patient is made much easier and
faster, and the risk of complications is reduced.
[0016] Another feature of the invention is a method of exposing a
selected area of the anterior lumbar region for a surgical
procedure on that region comprising the steps in the above
paragraph to expose the anterior lumbar region, and then retracting
the rectus muscle laterally; inserting a retractor into the
dissected field, the retractor comprising a handle portion and an
elongated blade portion having a first end connected to the handle
portion, the blade portion having a substantially flat
configuration which generally extends at an angle relative to the
handle, the blade portion having a second end spaced from the
handle portion and shaped as a lip which curves in a direction away
from the handle portion. The retractor is stabilized by engaging
the lateral aspect of a vertebral body or disc with the lip of the
retractor and retracting the tissues with the blade portion to
expose the selected vertebral area. This method offers the
advantages of secure retraction during further surgery, so that no
blood vessels, nerves, or other structures are damaged by the
retractor instrument, additional instruments, or accidental impact
during the surgery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] These and other features and advantages of the present
invention will be better understood by reference to the following
detailed description and accompanying drawings wherein:
[0018] FIG. 1 is a perspective view of one embodiment of a
retractor according to principles of this invention.
[0019] FIG. 2 is a side elevational view of the embodiment of the
retractor of FIG. 1.
[0020] FIG. 3 is a front elevational view taken on line 3-3 of FIG.
2.
[0021] FIG. 4 is a side elevational view of a malleable embodiment
of the retractor, showing the blade in two of many possible
operative configurations (solid and dashed lines).
[0022] FIG. 5 is a perspective view of an alternative embodiment of
a retractor according to principles of this invention.
[0023] FIG. 6 is an enlarged fragmentary perspective view taken
from the right side of the portion of the instrument shown within
the circle 6 of FIG. 5.
[0024] FIG. 7 is a side elevational view of the retractor shown in
the FIG. 5.
[0025] FIG. 8 is a fragmentary front elevational view taken on line
8-8 of FIG. 7.
[0026] FIG. 9 is a fragmentary rear elevational view taken on line
9-9 of FIG. 7.
[0027] FIG. 10 is a diagram of the common incision sites to access
lumbar vertebrae 3 and 4 (L3-4), lumbar vertebrae 4 and 5 (L4-5),
and lumbar vertebra 5 and sacral vertebra 1 (L5-S1).
[0028] FIG. 11 is a schematic representation of a retractor of the
invention in use, engaged against a lumbar vertebral body.
DETAILED DESCRIPTION
[0029] The retractor blade and procedure of the invention
demonstrate a novel approach to preparing any anterior lumbar
region exposure. They are particularly well suited to surgeries
needing only a small field, such as anterior fusions of two
vertebrae from L2 to S1, for example. The inventive surgical
approach to the lumbar area is rapid, requires only a small skin
incision, and it does not damage the rectus muscles or penetrate
the peritoneum, decreasing patient discomfort and recovery time.
The instrument of the invention is a retractor specially designed
to maximize the size of the surgical field and provide considerably
improved stability of the retractor under the relatively high
pressure/tension often needed to maintain clear access to the
spine. This increased stability and the width and other parameters
of the retractor blade also leads to a greatly decreased risk of
retracted tissues slipping into the surgical field and being
injured. The retractor and/or surgical method can be used in either
human or veterinary patients.
[0030] The Retractor Blade
[0031] FIGS. 1 through 4 show various one embodiment of a retractor
10 according to this invention. An alternate embodiment of a
surgical retractor instrument is shown in FIGS. 5 through 9 and
described below. The retractor 10 includes a long, narrow, rigid
handle portion 15 and an elongated thin, flat blade portion 20
which is shown extending generally at a right angle from an end of
the handle portion. The term "retractor" and "retractor blade" may
be used interchangeably herein, and is intended to mean the handle
15 and blade 20, but it is understood that the term "retractor" may
also be used in more general contexts to include related apparatus
used to stabilize the retractor handle/blade portion, such as a
self-retaining retractor system like the Bookwalter system (Codman
and Shurtleff, Inc.) or the Omni Retractor (Minnesota Scientific,
Inc.).
[0032] The retractor 10 is preferably made of metal, but can be
fabricated of any other suitable material (e.g., plastics). The
material requirements are similar to those for any surgical
instrument, e.g., that it can be cleaned and sterilized for reuse
by standard methods (e.g., sonication, autoclaving, UV
irradiation), it can withstand the forces put upon tools of this
sort (e.g., the elastic forces and weight of tissues retracted out
of their natural position), and that it be economical to produce
commercially. For the retractors of this invention, preferred
metals for fabrication are stainless steel, aluminum, or other
alloys. Alternative embodiments (e.g., single use disposable
instruments) are also within the scope of the invention, and the
inventive features of the retractor can be manufactured into any
retractor blade or self-retaining retractor system suitable for
anterior retroperitoneal access surgery. The blade portion of the
retractor can be formed of a single piece of suitable material,
molded, or made of two or more separate pieces of the same or
different material which are then assembled (e.g., the handle is
fastened to the blade) by means of, for example, solder or welds,
glue, pins, bolts, screws, or the like. The blade portion of the
retractor can be provided in a configuration suitable for use, or
it can be provided in another configuration (e.g., flat or linear)
and be bendable into a configuration suitable for use (described
more fully below). Thus, the blade portion of retractors of the
invention may be malleable or rigid. Preferably, only the blade
portion of the retractor is malleable, if any part of the retractor
is malleable.
[0033] Referring again to FIGS. 1-4, the handle 15 is square in
cross section, although any cross-sectional shape may be used.
Likewise, the handle 15 shown in FIG. 1 has ridges 18 which serve
to more stably anchor the handle in a clamping device, if one is
used; or conversely the ridges may prevent slipping of the
retractor if held by the digits of a hand. The ridges 18 can be
uniformly sized or not, and can be positioned straight up or
oriented at an angle (e.g., in a saw-toothed arrangement) to
preferentially reinforce the handle against slipping in a
particular direction, or to allow for adjustment of the position of
the handle (e.g., by ratcheting) in a retractor stand. The handle
15 shown in FIG. 1 is straight, for easier insertion into a
standard ring stand, arm, or other clamping device by means of an
adapter, as is common in surgical devices such as the Bookwalter
retractor system and others (see, e.g., U.S. Pat. Nos. 3,998,217,
4,813,401, 5,025,780, 5,052,373, 5,688,223, 5,728,046, 5,795,291,
5,902,233, 5,944,658). However, the handle 15 does not need to be
straight, and may be curved, or of any shape and dimension to adapt
to the preference of the user (for example, for holding in the
hand, to fit into specialized retractor devices, etc.). The handle
may be of any length, but is preferably between about 1-20 inches
in length, more preferably between about 6-8 inches in length.
Likewise, the thickness of the handle may vary, and need not be
uniform along the entire length of the handle. In a preferred
embodiment for use clamped in a retractor stand, the handle is
about 6.5 inches long and about 1 cm in diameter.
[0034] The blade portion 20 is generally initially planar, or
substantially flat, and connects to one end of the handle 15 at one
end of the blade. In rigid embodiments of the retractor, the blade
portion is substantially planar, while in malleable embodiments,
the bending of the blade portion may render it less planar and more
curved. The blade may be of any suitable width, but is preferably
from about 1 cm to 15 cm wide, and more preferably from about 2 cm
to 6 cm wide to prevent damage that wider blades can cause. The
length of the blade is likewise variable. The best length depends
upon the size of the patient the retractor is used on. For example,
a very thin or small person may require only about 5 cm of blade
length or less to restrain tissues during surgery, while an obese
person might require 20 cm or more of blade length for secure
retraction. Thus, the retractor can have blades of varying lengths,
preferably at least about 2 cm to 30 cm long, more preferably at
least 5 cm to 20 cm long. It is understood that malleable retractor
blades need not have as much variability in length, because they
can be bent along the blade portion into the desired length by the
user as needed. Preferably, malleable retractor blades are longer,
between about 7.5 to 30 cm long. The thickness of the blade portion
is preferably less than about 0.5 cm, more preferably less than
about 0.25 cm.
[0035] The blade 20 and the handle 15 can be joined in any
configuration, but when configured for surgical use, they will be
at an angle .theta. of less than 180.degree. with respect to each
other, preferably at an angle .theta. of about 90.degree. (about a
right angle, see FIG. 2) and substantially the entire blade will
extend below an axis aligned with the handle. For malleable blades
such as shown in FIG. 4, the angle when the retractor is configured
for use will not likely be the same over the length of the blade
portion with respect to the handle, because it will probably have a
controlled curvature over the length of the blade portion from
being bent by the user. The curvature is preferably minimized, with
no part of the blade protruding above or below about 2.5 cm from a
line drawn from the handle (or beginning of the bent portion in a
malleable retractor) to the portion of the blade just before the
lip starts to curve, more preferably less than about 1.5 cm.
[0036] Referring to FIGS. 1, 2, and 4, free the end of the blade 20
has a curved lip 25 having a leading edge 28 which is the
distal-most edge of the blade (with respect to the (proximal)
handle) and the end of the curved lip portion 25. When the
retractor 10 is in a usable configuration (having an angle .theta.
less than 180.degree.), the curve of this lip is outward, or in a
direction roughly opposite to the direction of the handle (see
FIGS. 2 and 4 (silhouette)). The orientation of this lip is
critical. The lip generally will comprise no more than between
about 0.5 to about 5 cm of the blade length, more preferably about
1 cm to about 1.5 cm of the blade length, most preferably about
1.25 cm of the blade length. The lip curves out of the general
plane of the substantially flat blade surface preferably no more
than about 5 cm (vertical height), more preferably no more than
about 2 cm, most preferably no more than about 0.3 to about 0.7 cm.
The curve of the lip is preferably relatively shallow (e.g.,
preferably having a radius of curvature of between 1 cm and 3 cm
and curving over about 20-50.degree. of the circle of curvature,
more preferably having a radius of curvature between about 1.5 cm
and about 1.8 cm and curving over about 25-40.degree. of the circle
of curvature). The curvature is sufficient to allow the lip 25 to
wedge under or against the general curvature (in shape and degree)
of the body of the lumbar vertebrae 70 when placed generally
perpendicular to a vertebra and/or disc as it lies in the body
aligned in the spine (FIG. 11). The lip 25 serves to lodge the
retractor firmly into position when it is deployed against the
vertebral body 70 or disc. This minimizes the risk of the retractor
slipping during surgery. This is desirable since slippage can lead
to retracted tissues entering the field of surgery and being
damaged. Consequences of such damage are permanent nerve injury,
hemorrhage, ureter or organ injury, etc. These injuries are the
most common complications of anterior lumbar surgery, and the
retractor blade of the invention greatly reduces the risks, simply
by providing greatly improved stability during use.
[0037] In a preferred embodiment, the side of the lip 25 opposite
the handle (e.g., the side that will face the vertebral body during
use), and/or the leading edge 28 of the lip have a roughened
surface. This roughness adds additional purchase or "stickiness" to
the interaction between the retractor and the bone surface,
reducing the possibility of slippage even further.
[0038] FIGS. 5 through 9 show an alternate embodiment of a surgical
retractor used for the same purpose as the retractor shown in FIGS.
1 through 4. The retractor 30 has an elongated thin, flat handle
portion 32 having a connector 34 for securing it to a separate
instrument used to guide the retractor during surgery. The function
and various configurations of the handle are similar to those
described previously for the instrument of FIGS. 1 to 4. In the
illustrated embodiment, the instrument 30 includes an elongated
thin flat blade portion 36 bent at a generally right angle to the
handle so that the handle extends away from one end of the blade.
The side edges of the blade portion are generally parallel to one
another, and the blade has a range of possible lengths similar in
dimension to those described for the instrument of FIGS. 1 to 4. A
preferred range of lengths of the blade 34 is from about 10 to
about 20 cm. The blade generally can have a width from about 2 cm
to about 5 cm. The preferred width of the blade is from about 2.5
cm to about 3 cm. The thickness of the blade is less than about
0.25 cm and the preferred blade thickness is about 0.16 cm.
[0039] The free end of the blade has a curved lip 38 having a
leading edge 40 at the distal end of the blade. The lip curves
outward similar to the retractor in FIGS. 1 to 4, in an opposite
direction generally away from the direction in which the handle
extends. The distal end of the blade is generally rounded so that
the opposite sides of the lip portion are essentially continuous
with the parallel sides of the blade. The sides of the blade
extending toward the lip narrow (or taper) toward each other along
a flat portion of the blade above a juncture 42 where the lip
begins to curve away from the flat plane of the blade. The lip
portion of the blade extends for a very short distance compared to
the length of the blade itself. The lip is preferably less than 10
percent in length compared to the length of the blade. The curved
lip below the juncture 42 has a length (in a direction along the
axis of the blade) of about 0.2 to about 0.6 cm, and more
preferably, about 0.3 to about 0.5 cm.
[0040] The lip curves away from the plane of the blade preferably
by no more than about 2 cm. In the illustrated embodiment this
distance from the distal end of the lip to the flat surface of the
blade is about 0.15 to about 0.5 cm and, more preferably, about
0.15 to about 0.3 cm. The curvature of the lip is relatively
shallow and has generally the same radius of curvature as the
curvature described for the instrument of FIGS. 1 to 4.
[0041] The lip has a width of least about 1.75 cm. In one
embodiment, in which the blade has a width of about 2.5 cm, the
width of the lip is about 1.9 to about 2.1 cm. In another
embodiment, in which the blade has a width of about 3.0 cm, the
width of the lip is about 2.3 to about 2.6 cm. The width of the lip
is measured across the juncture 42 where the lip begins to curve
away from the flat plane of the blade member.
[0042] The front face of the lip is preferably roughened in a
manner similar to the instrument shown in FIGS. 1 to 4. In the
illustrated embodiment, the roughening is produced by a pair of
parallel thin narrow grooves 44 which extend generally parallel to
the juncture 42 at the bottom region of the lip.
[0043] The curvature of the lip is sufficient to allow the lip to
wedge under or against the generally curvature of the body of the
lumbar vertebra when placed generally perpendicular to a vertebra
and/or disk as it lies in the body against the spin. The lip serves
to lodge the retractor firmly into position when it is deployed
against the invetebral body or disk. This minimizes the risk of the
retractor slipping during surgery.
[0044] Surgical Approach to the Anterior Lumbar Region
[0045] The surgical method of the invention is an anterior
retroperitoneal rectus muscle sparing approach to the spine in the
region of lumbar vertebra 2 (L2) to sacral vertebra 1 (S1). In
addition to the advantages of leaving the rectus muscle intact, the
method minimizes damage to peritoneal structures and blood vessels
associated with the lumbar region. This method exposes the spine in
the specific region desired, generally pairs of vertebra (e.g.,
L2-3, L3-4, L4-5, or L5-S1), for surgical intervention, such as
disc repair, removal, and/or vertebral fusion. The method can be
adapted to expose more vertebrae if desired. If pairs of vertebrae
are exposed, as is usual, the method requires only an exceptionally
small skin incision, one of many advantages of the method.
[0046] In preparation for the procedure, the patient is placed in
the supine position on a Jackson or other X-ray table with an
inflatable bag under the lumbar region. Inflation of the bag will
allow for extension of the spine at the time of discectomy and
graft placement, and the X-ray table allows radiographic images to
be taken during the procedure to ascertain the position of the
surgeon along the spine.
[0047] Generally, the approach surgeon stands on the left and the
assistant on the right. The approach to the spine is preferably
from the patient's left side to avoid the vena cava, which
anatomically lies to the right of the spine. The incision is begun
at the midline of the body and carried transversely to the lateral
edge of the rectus muscle. The level of the incision in the
cranio-caudad plane depends on the level of the spine approached,
and will generally be in the regions shown in FIG. 10.
[0048] The incision for L5-S1 access is usually at the junction of
the lower and middle thirds of the distance between the umbilicus
and the symphisis pubis. This incision, however, needs to be moved
caudad or cephalad depending on the angle of L5-S1 as seen on a
lateral plain X-ray film. In other words, the degree of pelvic
tilt, lordosis, or other individual variability must be considered.
Proper placement of this small incision by the approach surgeon is
crucial to the spinal surgeon in placing the working sleeves for
vertebral fusion operations at the proper angle parallel to the
vertebrae.
[0049] For L4-5 access, the incision is placed just below the
umbilicus, and for L3-4, the incision is placed just above the
umbilicus 75 (FIG. 10). For L2-3 access, the incision is placed
about 5 cm above the umbilicus. Lateral X-rays can be used to
evaluate the placement of the skin incision at the upper levels as
well, since there is frequently some anatomical variation that may
influence the placement of the incision 1 or 2 cm higher or lower.
For two- or more-level exposure (e.g., more than one disc to be
exposed), the incision should be more oblique, starting at the
level of the lower disc and ending at the level of the upper disc.
If the midline of the body is the reference line (0.degree. toward
the head, 180.degree. toward the feet), a single-level exposure
will require an incision of about 70-90.degree., preferably about
80.degree.. A two-level exposure will require an incision of about
35-55.degree., preferably about 45.degree., and a three or more
level exposure will require an incision of between about
10-45.degree., preferably between about 25-35.degree.. The
incisions using the method of the invention are smaller than those
normally used for similar exposures.
[0050] The incision is carried to the anterior rectus sheath using
electrocautery and the subcutaneous portion of the incision is
carried beyond the ends of the skin incision both medially and
laterally. This will expose a subcutaneous area beyond the midline
as well as the external oblique aponeurosis. The rectus sheath (or
fascia) is incised from about 1 cm to the right of the midline to
the edge of the rectus laterally. The anterior rectus sheath is
then elevated anteriorly away from the muscle belly for a distance
of about 6 to 8 cm both superiorly and inferiorly to allow for full
mobilization of the rectus muscle. The muscle is freed from any
connective tissue all around the body of the muscle. Posterior
dissection of the muscle is carried out bluntly, taking great care
to avoid injury to the inferior epigastric vessels, which run along
the undersurface of the muscle and must be elevated with the muscle
and retracted with it using an appropriate curved retractor.
Preservation of this neurovascular bundle is essential in
preventing denervation of the muscle. Because the muscle is freed
and mobilized in both directions from the single incision point of
the fascia/sheath, no additional incisions of the sheath are
needed, unlike prior methods. The rectus muscle mobilized in this
way can easily be retracted medially or laterally, and no damage
has been done to the muscle itself, making the patient's recovery
much faster and less painful.
[0051] With the rectus muscle initially retracted medially, the
posterior sheath or transversalis fascia is carefully incised about
4-5 mm until the peritoneum is seen to shine through. The edges of
the cut fascia are grasped with a hemostat, then lifted away and
very carefully dissected from the peritoneum and incised as far
inferiorly and superiorly as possible. This layer can be quite
tenuous and care must be exercised to prevent peritoneal
lacerations. The peritoneum will now bulge upward. Using a finger,
the surgeon next carefully pushes the peritoneum posteriorly at the
edge of the rectus fascia and slowly develops a plane between it
and the undersurface of the internal oblique and transversus
muscles and fascia. This opening leads into the retroperitoneal
space. Careful blunt finger dissection is continued posteriorly and
then the surgeon should begin pushing medially to elevate the
peritoneum away from the psoas muscle. If the peritoneum is
accidentally entered at any point, the tear should be repaired with
absorbable suture material at that time. Delaying this repair will
only lead to major peritoneal repairs later on. The surgeon should
be careful not to enter the retro-psoas space at this point as this
will lead to unnecessary bleeding in a blind pouch. The
genito-femoral nerve can be easily identified over the psoas. The
ureter can usually be identified as the peritoneum is lifted away
from the psoas. Both of these structures should be protected from
injury. Once the psoas is identified, the surgeon should palpate
medially to feel for the disc space and body of the vertebrae, and
the iliac artery. At this point, the entire hand may be inserted
(if the size of the incision allows) and a fist made in the
retro-peritoneal area. The peritoneum is elevated away in all
directions by sweeping the area with the closed fist up and down. A
Balfour retractor or the like with appropriately deep blades is
then inserted to keep the incision open in the cranio-caudad plane.
A dry lap sponge tucked above the upper blade of the Balfour is
helpful in keeping retro-peritoneal fat from creeping down and
obscuring the field. A Harrington retractor or similar is used to
keep the peritoneal contents away from the vessels and allow
further dissection.
[0052] For operations on L5-S1, the dissection is then carried
anterior and medial to the left iliac artery with the Harrington
retractor preferably placed into that plane to elevate the
peritoneal contents. The disc between L5-S1 is palpated and the
dissection is carried toward it with blunt dissection between the
iliac vessels and below the aortic bifurcation. The iliac vein is
seen deep to the artery and swept towards the left to expose that
side of the disc. Dissection towards the right exposes that side of
the disc and a retractor of the invention, a reverse-lipped,
optionally malleable retractor (described above) can be used to
maintain exposure to that side by anchoring the lip on the lateral
aspect of the spine. The iliac vessels are not usually visualized
on the right side. The middle sacral vessels can be taken between
clips or ligatures, keeping cautery to a minimum, particularly in
males, to preserve the superior hypogastric plexus fibers. The left
iliac vein sometimes needs to be widely mobilized to allow
placement of the reverse-lipped, malleable retractor against the
left lateral edge of the spine. The Bookwalter or similar retractor
is used to keep two reverse-lipped (malleable) blades in place
during discectomy and placement of hardware, bone grafts, etc.
[0053] For operations on only L4-5 or for operations that combine
L4-5 with either L3-4 or L5-S1, the ileo-lumbar vein(s) must be
ligated and cut as they serve as a tether preventing mobilization
of the iliac vein away from the anterior surface of the spine and
thus prevent proper exposure. A Deaver, Harrington, or similar
retractor is placed into the plane above the artery to elevate the
peritoneal contents away. The surgeon then dissects bluntly just
above the iliac artery and moves the retroperitoneal tissues away
from the artery. The entire length of the common and external iliac
arteries are exposed as far distally as possible, and then a
careful blunt dissection is started along the lateral edge of the
artery. This will expose the left common iliac vein just underneath
the artery. The dissection is continued posteriorly to identify the
ileo-lumbar vein(s), which crosses the body of L5 and dives into
the left paraspinous area. Variations in the formation of the
common iliac vein and the lumbar veins are common and great care
must be exercised in order to identify, ligate and transect these
veins and avoid accidental avulsion or other trauma. Ligation
should be carried out in place prior to transection and not too
close to the ligated vein's junction to the iliac vein itself in
order to avoid injury to the iliac vein's sidewall. For any
operation that involves L4-5, these maneuvers are imperative to
safely mobilize the interfering vasculature away from the surgical
field.
[0054] The left iliac vein and artery can now be separated away
from the spine using gentle peanut sponge, fingertip and blunt
elevator dissection. In most patients the vein "peels" away from
the anterior surface of the spine easily. In some patients,
however, there is intense inflammatory reaction in the plane
between the vein and the anterior longitudinal ligament, especially
when osteophytes are present; so the dissection can be quite
difficult and tedious. All the vascular structures are thus swept
from left to right to provide adequate visualization of the disc(s)
and vertebral bodies involved. Segmental vessels running across the
valleys on the anterior surface of the bodies can be transected
between clips and swept to the sides with blunt dissection. The
surgeon should be sure to make sufficient room to get at least one
finger between the common iliac vein and the anterior longitudinal
ligament (ALL) in order to palpate the right lateral edge of the
spine with the vessels above the finger(s). Care must be taken not
to tear tissues that don't give way easily, because in doing this,
the surgeon may tear lumbar veins coming in from the right side.
Once this part of the exposure is completed, the retractors (e.g.,
Balfour and Harrington) are removed.
[0055] At this point, the dissection of the surgical field is
complete, and it remains to retract the peritoneum, vasculature,
and other tissues away from the spine to provide a clear exposure
of the disc(s) and vertebrae of interest.
[0056] Use of the Retractor to Maintain Anterior Retroperitoneal
Lumbar Exposure During Spine Surgery
[0057] Preferably, a Bookwalter self-retaining retractor post and
ring system (or similar arrangement) is then set up. It is
understood that manual retraction can also be used with the
retractors of the invention, but the use of a retractor post and
ring increases the stability of the retraction, and eliminates
human error/variability and reduces the risk of the retractors
slipping.
[0058] The rectus muscle is now retracted laterally, rather than
medially as it was for the initial dissection, in order to reduce
the amount of pull on the muscle going forward with the operation.
This positioning also has the advantage that the muscle is not
damaged during the surgery, as prolonged retraction medially might
cause.
[0059] The surgeon's hand then re-enters the retro-peritoneal space
with the rectus now moved laterally, and the fingers find their way
to the right side of the spine following the planes previously
dissected. The retractor, either rigid or malleable, and having the
small reverse lip, bent to (if malleable) or having the appropriate
blade length for the patient's size, is then placed blindly onto
the right side of the spine using the finger(s) as a guide to place
the leading edge of the lip securely against the spine. This blade
is then pushed to the right, attached to the ring of the retractor
stand by standard means (e.g., a clamp or adaptor), then pushed
further to elevate the vascular structures and expose the anterior
surface of the spine. Once secured to the ring of the
self-retaining retractor system (e.g., Bookwalter), the retractor
will not move. The lip keeps the blade anchored to the edge of the
spine and prevents it from slipping anteriorly once tension is
applied. Without this lip, the retractor blade will not work and
the risk of the retractor slipping is greatly increased.
[0060] With the rectus now retracted laterally, there will be much
less resistance when pushing the retractor blade to expose the
spine in a direct anterior-posterior view. A second such retractor
blade is placed on the left side of the spine and attach to the
ring to complete the exposure. When rigid blades are used that have
about a right angle to the handle, the field is clear straight down
from the retractors' insertion point. The straight approach and
reliable clearance of tissue from the exposure means that a much
smaller incision is necessary to allow placement of the sleeves
used for disc and fusion surgery (e.g., for insertion of a threaded
device or femoral ring) than if curved retractor blades are used.
Occasionally, additional retractor blades need to be placed
superiorly or inferiorly to complete the exposure. X-rays should be
taken after the first two blades are placed so as not to obscure
the field with too much hardware. With these blades well anchored
to the lateral wall of the vertebrae, the spine surgeon and his
assistant can now work on the disc without other hands or
retractors being in the way and with relative security that vessels
will not sneak around the retractors and expose themselves to
injury. Utmost care, however, needs to be exercised to prevent such
injuries.
[0061] For operations of L3-4 and L2-3 mobilization of the iliac
vessels is usually not necessary, and only occasionally will the
surgeon need to transect the ileo-lumbar vein(s) to obtain adequate
mobilization. This makes approaching these two levels somewhat
easier.
[0062] When approaching L4-5 and L5-S1, it is usually necessary to
get to L5-S1 between the common iliac vessels and to L4-5 lateral
to them. Occasionally, L5-S1 can be exposed via the lateral
approach used for L4-5 if the aortic bifurcation is low in the
patient. In these cases, one can actually see both levels
simultaneously with only minimal adjustment of the retractor and
its blades to provide optimal access. Only rarely, however, is it
possible to expose L4-5 by going between the vessels after having
completed the exposure of L5-S1.
[0063] Spinal surgery, such as discectomy and instrumentation can
be performed after the above steps have been completed. Upon
completion of the spinal procedure, the left retractor is
preferably removed first, then the one on the right, and the
integrity of the vessels is checked thoroughly, especially looking
for arterial thrombosis or injury due to stretching.
[0064] Then all retractors and lap sponge(s) are removed and the
tissues are allowed to fall back together anatomically. The
individual fascial layers are then closed separately with running
absorbable sutures, making sure that the anterior rectus sheath is
well approximated. The posterior sheath need not be closed if it is
tenuous and does not offer any significant strength to the closure.
A thick, substantial posterior rectus sheath, however, should be
closed. Subcutaneous tissues and skin are then closed as per
surgeon's preference. No Steinman pins are ever used for retraction
with this approach, as they only increase risk of vessel
perforation, and the retractor of the invention is sufficient alone
to hold back the tissues with the necessary level of security.
[0065] The preceding description has been presented with reference
to presently preferred embodiments of the invention. Workers
skilled in the art and technology to which this invention pertains
will appreciate that alterations and changes in the described
structure may be practiced without meaningfully departing from the
principal, spirit and scope of this invention.
[0066] Accordingly, the foregoing description should not be read as
pertaining only to the precise structures described and illustrated
in the accompanying drawings, but rather should be read consistent
with and as support to the following claims which are to have their
fullest and fair scope.
* * * * *