surgical needles
A surgical suturing needle is disclosed for use in limited space
applications as well as a method for its use. The needle has an
arcuate body and a relatively straight shank extending therefrom.
The shank and arcuate body form an abrupt angle therebetween.
The surgical suturing needle has a pointed tip on one end of the
arcuate body and suture attachment structure formed in the shank.
The method of using the surgical needle to join a pair of vascular
tissue sections together includes penetrating into a lumen of
a first vascular tissue section, advancing the pointed tip into
the lumen of a second vascular tissue section and out through
a side wall thereof, grasping the pointed tip and drawing the
needle substantially parallel to an outer surface of the second
vascular tissue section to thereby move the surgical suturing
needle and an attached length of suture material through the first
and second vascular tissue sections.
Claims:
What is claimed is:
1. A surgical suturing needle comprising:
an arcuate body having a pointed tip at one end thereof; and
a relatively straight shank formed adjacent an opposite end,
the juncture of the shank and the arcuate body forming an immediate
abrupt angle in a range of about 30.degree. to about 70.degree.
therebetween, the arcuate body being measured from the immediate
abrupt angle to the pointed tip wherein a radius of curvature
of the arcuate body progressively increases form the juncture
with the shank to the pointed tip.
2. The surgical suturing needle as recited in claim 1, wherein
the abrupt angle is an acute angle.
3. The surgical suturing needle as recited in claim 1, wherein
the abrupt angle is approximately 45.degree..
4. The surgical suturing needle as recited in claim 1, wherein
the length of the shank is less than the radius of the arcuate
body.
5. The surgical suturing needle as recited in claim 1, wherein
the length of the shank is approximately 10-45% of the overall
length of the surgical suturing needle.
6. The surgical suturing needle as recited in claim 1, wherein
the length of the shank is approximately 0.05 to 0.15 inches.
7. The surgical suturing needle as recited in claim 1, wherein
a portion of the arcuate body has relatively flat sides.
8. The surgical needle as recited in claim 1, wherein the shank
has a substantially circular cross-section.
9. The surgical suturing needle as recited in claim 1, further
comprising suture attachment structure formed in the shank.
10. A surgical suturing needle comprising:
an arcuate body having a pointed tip at a first end, the arcuate
body having a radius of curvature which progressively increases
from a second end of the arcuate body to the pointed tip; and
a relatively straight shank formed adjacent the second end and
having a bore therein for receipt of an end of a length of suture
material, wherein a juncture of the shank and the arcuate body
defines an abrupt angle in a range of about 30.degree. to about
70.degree..
11. The surgical suturing needle as recited in claim 10, wherein
the abrupt angle is approximately 45.degree.
Description:
BACKGROUND
1. Technical Field
This disclosure relates generally to surgical needles and methods
of suturing and, more particularly, to a surgical needle and method
of use particularly suited for use in limited space applications,
such as, cardiovascular or microvascular surgery.
2. Description of Related Art
Various shapes and styles of surgical needles have been developed
for use with specific suturing procedures. The needle configurations
may vary according to the type of tissue to be sutured and the
manner of manipulating the needle during suturing. For example,
one such needle, used for suturing deep facia tissue, is disclosed
in U.S. Pat. No. 5,433,728 to Kim ("Kim"). The Kim needle
has an arcuate body with a pointed tip. The body forms an arc
of approximately 180.degree. to 230.degree. and is joined to a
relatively straight shank by a gently curving arcuate neck.
Another specific needle configuration is disclosed in European
Patent Application No. 0494644 A2 ("EPO '644) The EPO '644
needle is disclosed for use in abdominal surgery and one embodiment
includes a straight section which bends downwardly at approximately
22.degree. and then curves upwardly with a radius of 5/12ths of
the needle's overall length.
In certain surgical procedures, for example, cardiovascular or
microvascular surgery, it is often necessary to join two hollow
organ or vascular tissue sections together. This is most often
accomplished by suturing opposing edges of the vascular tissue
sections together. The type of surgical suturing needle used during
these procedures typically is a needle having an arcuate shape
of a substantially constant radius. Most often the arc of the
needle encompasses having a pointed tip at one end and a tail
portion at an opposite end which is drilled to retain an end of
a length of suture material therein.
In order to suture two opposing vascular tissue sections together
with prior art microvascular or cardiovascular surgical needles
of the type described above, the suturing needle is typically
held at its tail portion by a needle holder and rotated about
the center of its radius through the tissue sections to be joined.
For example, in order to suture two vascular tissue sections together,
the two vascular tissue sections are approximated and the surgical
needle having a length of suture attached thereto is rotated to
cause the pointed tip to pierce through an outer wall of a first
vascular tissue section and into its lumen. The needle is then
rotated further to move the pointed tip of the needle through
a lumen of the second vascular tissue section and out through
an outer wall of the second vascular tissue section. Once the
pointed tip has penetrated through the wall of the second vascular
tissue section, the pointed tip is grasped with a needle holder
and the tail portion is released.
In order to draw the length of suture through the two vascular
tissue sections and remove the needle from the vascular tissue
sections, it is necessary to continue to rotate the surgical needle
further in approximately a half circle drawing the suture material
through the tissue sections. During rotation of the needle through
the vascular tissue sections, the force of the tail portion against
the initial entrance hole in the first vascular tissue section
may cause the entrance hole to become traumatized or enlarged.
Since during the entire surgical procedure the needle must be
rotated through approximately a complete circle, an operating
space having a height more than half of the radius of the needle
must be available adjacent the accessed vascular tissue sections.
In certain specific procedures, such as cardiovascular or microvascular
surgical procedures, a very limited amount of space adjacent the
accessed tissue sections is available for manipulation of the
surgical needle. This is especially true when suturing behind
the aorta. The proximity of tissue walls to the vascular tissue
sections inhibits the surgeon's ability to substantially rotate
a conventional surgical needle when suturing these tissues. Thus,
there exists a need for a cardiovascular and/or microvascular
surgical suturing needle configured to be manipulated within a
limited space and with minimal trauma to the tissue sections to
be sutured.
SUMMARY
There is disclosed a surgical needle which is particularly suited
for use in limited space applications and a method for its use.
The surgical needle includes an arcuate body having a pointed
tip at one end. At an opposite end of the arcuate body there is
provided a relatively short, straight shank which extends from
the arcuate body at a predetermined angle. The predetermined angle
is defined by the intersection of the arcuate body and the shank.
In a preferred embodiment, this predetermined angle is preferably
within a range of about 30.degree. to 70.degree., with approximately
45.degree. representing an optimum configuration. Preferably,
an extrapolation of the longitudinal axis of the shank does not
intersect any other portion of the surgical needle.
The arcuate body may have either a varying or a constant radius
of curvature and preferably has a varying radius of curvature
which increases progressively from the juncture with the shank
toward the pointed tip. The surgical needle generally has a circular
cross-section, however, in a preferred embodiment, a portion of
the arcuate body may be formed with flat sides. Other cross-sectional
configurations are also applicable and are contemplated by this
disclosure. Suture attachment structure in the form of a counter
sunk bore is provided in the shank. A suture may be attached thereto
using any number of various known techniques, such as, for example,
crimping, medical grade adhesives, etc.
A method of using the surgical needle is also disclosed. The
method includes initially grasping the shank of the surgical needle
with a needle holder. The pointed tip of the surgical needle is
then forced against the wall of the first tissue section and driven
into the lumen. The surgical needle is then manipulated to advance
the pointed tip and arcuate body through the first lumen into
a second lumen of the second vascular tissue section. The point
ed tip is manipulated to penetrate the wall of the second vascular
tissue section and protrude from an outer wall thereof. The pointed
tip of the surgical needle is grasped with a needle holder and
the shank is released. The surgical needle is then pulled substantially
parallel to an outer surface of the second vascular tissue section
to thereby draw the surgical needle through the entrance hole
and out the exit hole to thereby form a stitch.
BRIEF DESCRIPTION OF THE DRAWING
Various embodiments are described hereinbelow with reference
to the drawings, wherein:
FIG. 1 is a perspective view of a prior art surgical needle;
FIG. 2 is a perspective view of one embodiment of the present
surgical needle;
FIG. 3 is a cross-sectional view taken along line 3--3 of FIG.
2;
FIG. 4 is a cross-sectional view taken along line 4--4 of FIG.
2;
FIG. 5 is a cross-sectional view taken along line 5--5 of FIG.
2;
FIG. 6 is a perspective view, partially shown in section, of
the prior art needle of FIG. 1 initially penetrating a first vascular
tissue section;
FIG. 7 is a view similar to FIG. 6 illustrating the prior art
needle after penetrating a second vascular tissue section;
FIG. 8 is a view similar to FIG. 7 illustrating the prior art
needle being drawn through the tissue sections;
FIG. 9 is a view similar to FIG. 8 illustrating the prior art
needle after it has been drawn through the first vascular tissue
section;
FIG. 10 is a view similar to FIG. 9 illustrating the prior art
needle after it has been drawn through the second vascular tissue
section;
FIG. 11 is a perspective view, partially shown in section, illustrating
the surgical needle of FIG. 2 penetrating a first vascular tissue
section;
FIG. 12 is a view similar to FIG. 11 illustrating the surgical
needle of FIG. 2 penetrating a second vascular tissue section;
FIG. 13 is a view similar to FIG. 12 illustrating the surgical
needle of FIG. 2 being drawn partially through the first vascular
tissue section;
FIG. 14 is a view similar to FIG. 13 illustrating the surgical
needle of FIG. 2 being drawn completely through the first vascular
tissue section;
FIG. 15 is a view similar to FIG. 14 illustrating the surgical
needle of FIG. 2 being drawn out through the second vascular tissue
section; and
FIG. 16 is a partial view of the prior art view of FIG. 10 showing
removal of the prior art suturing needle from a tissue section.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring initially to FIG. 1, there is shown a prior art surgical
suturing needle 10 of the type typically used in cardiovascular
or microvascular surgery. Needle 10 generally includes an arcuate
body 12 typically having a constant radius of curvature "r".
A pointed tip 14 is formed on one end of arcuate body 12 and a
tail portion 16 is formed on an opposite end of arcuate body 12.
Preferably, tail portion 16 includes a bore 18 for receipt of
an end of a length of suture material therein. When used in cardiovascular
and microvascular applications, needle 10 generally has an overall
length "1" on the order of approximately 0.200 to 2.000
inches preferably about 0.305 to about 0.365 inches and most preferably
about 0.328 to about 0.338 inches and a radius on the order of
about 0.1 to about 2.0 inches. While surgical needle 10 is illustrated
as forming half a circle with constant radius r, prior art surgical
needles are also available in styles forming greater or less than
half of a circular arc, for example, three eights of a circular
arc.
Referring now to FIG. 2, there is illustrated a preferred embodiment
of surgical needle 20. Surgical needle 20 includes a generally
arcuate body 22 having a variable radius "R.sub.v "
and a relatively straight shank 28 extending from arcuate body
22. A pointed tip 24 is formed at a first end 26 of arcuate body
22 and shank 28 is formed on a second end 30. Arcuate body 22
is preferably solid, however, other configurations are also contemplated,
such as, for example, fully or partially hollow, channel-shaped,
etc. Variable radius R is substantially larger than that used
with known surgical suturing needles, such as prior art needle
10 above, and gives a generally more flat profile to arcuate body
22. As noted above, radius R preferably varies, increasing from
the juncture with shank 28 to pointed tip 24. Shank 28 forms a
relatively abrupt juncture angle a with second end 30 of arcuate
body 22. As used herein the term "abrupt" indicates
distinct transition as opposed to gradual melding of one portion
into another. Preferably, juncture angle a is on the order of
approximately 30.degree. to 70.degree., and more preferably, approximately
45.degree.. It should be noted that an extrapolation of the longitudinal
axis 29 of shank 28 does not intersect any other portion, for
example, arcuate body 22, of surgical needle 20. Radius R preferably
ranges from about 0.100 to about 2.00 inches and surgical needle
20 generally has an overall length L of approximately 0.305 to
0.365 inches. Shank 28 preferably has a length of approximately
0.055 inches to 0.130 inches, and more preferably, 0.100 inches.
As noted above, arcuate body 22 has a relatively large and varying
radius R. In addition, surgical needle 20 may have consistent
or varying cross-sectional shapes. Referring now to FIG. 3, arcuate
body 22 has a generally circular cross-section adjacent pointed
tip 24. However, as shown in FIG. 4, a portion of arcuate body
22 may be imparted with relatively flat sides 34 to increase strength
and facilitate use. Shank 28 also has a generally circular cross-section
and, as shown in FIGS. 2 and 5, includes suture attachment structure
in the form of a bore 32 formed within shank 28 for receipt of
an end of a length of suture material therein. The end of the
length of suture material may be secured within bore 32 by known
attaching techniques, such as, for example, crimping or use of
surgical grade adhesives such as, for example, cyanoacrylate glue,
epoxy cements or other medically acceptable adhesives.
Referring now to FIGS. 6-10, a brief description of the method
of suturing an opposed pair of vascular tissue sections utilizing
the prior art surgical needle 10 will now be described. As noted
hereinabove, suturing with surgical needle 10 typically requires
that surgical needle 10 be rotated almost completely about its
center of radius, thus necessitating a significant amount of operating
space adjacent the vascular tissue sections to be sutured.
Referring initially to FIG. 6, in order to suture two vascular
tissue sections together, the distal end of a first vascular tissue
section A having a wall B defining a lumen C therein is approximated
adjacent a distal end of a second vascular tissue section E having
a wall F and defining a lumen G therein. The tail portion 16 of
surgical needle 10 is grasped with a needle holder 36 to manipulate
the surgical needle. Surgical needle 10 is provided with a length
of suture material 38 affixed within suture bore 18. Pointed tip
14 is positioned adjacent wall B and driven therethrough by rotating
surgical needle 10 about its center of radius r. As surgical needle
10 penetrates wall B it creates an entrance hole D in wall B.
Surgical needle 10 is rotated such that it passes through lumen
C and into lumen G in second vascular tissue section E.
Referring now to FIG. 7, once a portion of surgical needle 10
has entered lumen G of the second vascular tissue section E, surgical
needle 10 is rotated further to penetrate wall F thereby causing
an exit hole I to be created in wall F. Pointed tip 14 is then
grasped with a second needle holder 36 and the tail portion 16
is released from the first needle holder 36. Thus, having penetrated
through both first and second vascular tissue sections A and E,
surgical needle 10 is ready to be withdrawn from vascular tissue
sections A and E thereby drawing a length of suture material 38
through vascular tissue sections A and E to form a stitch.
In order to draw surgical needle 10 through vascular tissue sections
A and E, needle 10 is rotated further about its center of radius
to draw a length of suture material into lumen C. As shown in
FIG. 8, upon rotating surgical needle 10, tail portion 16 may
press against edges of entrance hole D thereby enlarging the entrance
hole and causing trauma thereto. If this trauma is significant,
separate and additional stitching procedures may be required to
close the enlarged entrance hole and prevent leakage.
Referring now to FIGS. 9 and 10, surgical needle 10 is rotated
still further to draw surgical needle 10 through lumens C and
G, and out through exit hole I thereby drawing length of suture
material 38 through entrance and exit holes D and I to suture
or stitch vascular tissue sections A and E together. With particular
reference to FIG. 10, it can be easily seen that as surgical needle
10 is rotated out of vascular tissue section E, surgical needle
10 requires a significant amount of space in order to be manipulated,
the height of this space is indicated by height "h",
adjacent the outer surface of the vascular walls B and F. Further,
as indicated above in FIG. 6, initial penetration of the first
vascular tissue section A also requires a significant amount of
space adjacent the outer wall B.
Thus, the suturing of vascular tissues with the known prior art
surgical suturing needles of the type shown as suturing needle
10 typically requires a significant amount of operating space
adjacent the vascular tissue sections in order to properly manipulate
surgical needle 10.
Referring now to FIGS. 11-14, the provision of surgical needle
20 permits vascular tissue to be sutured using significantly less
operating space adjacent the vascular tissue sections being sutured.
Referring initially to FIG. 11, surgical needle 20, attached to
suture material 40, may be utilized to suture together two opposed
vascular tissue sections such as, first vascular tissue section
A' and second vascular tissue section E'. First vascular tissue
section A' has an outer wall B' and defining a lumen C' therein
and second vascular tissue section E' has an outer wall F' and
defining a lumen G' therein.
Initially, surgical needle 20 is grasped adjacent its shank 28
by needle holder 36. Pointed tip 24 is positioned adjacent wall
B' and moved through and into inner lumen C'. The larger radius
of curvature of arcuate body 22 adjacent pointed tip 24 allows
pointed tip 24 to be driven into wall B' without having to substantially
rotate surgical needle 20. As surgical needle 20 is passed through
wall B' it creates an entrance hole D'. Surgical needle 20 can
then be manipulated to advance arcuate body 22 through entrance
hole D' and to advance pointed tip 24 into lumen G' of second
vascular tissue section E'. Surgical needle 20 is then manipulated
to cause pointed tip 24 to penetrate wall F' to create an exit
hole I'. The smaller radius of curvature adjacent shank 28 facilitates
driving pointed tip 24 through wall F' with a minimal amount of
rotational motion. Shank 28 is thus positioned flush with or parallel
to an outer surface of first vascular tissue section A'.
Referring to FIG. 12, once pointed tip 24 has penetrated wall
F' thereby creating exit hole I', shank 28 is released from the
grasp of needle holder 36 and pointed tip 24 is grasped. In contrast
to the rotational motion used to move prior art surgical needle
10 through the vascular tissue sections, surgical needle 20 is
configured to be moved substantially parallel to a longitudinal
axis of the vascular tissue sections. As shown in FIGS. 11 and
12, this motion of moving surgical needle 20 parallel to the longitudinal
axis of the vascular tissue sections requires a significantly
smaller amount of operating space adjacent the vascular tissue
sections.
Referring now to FIG. 13, as pointed tip 24 is grasped by needle
holder 36 and moved substantially longitudinally parallel to second
vascular tissue section E', shank 28 is atraumatically drawn through
entrance hole D' in first vascular tissue section A'. This is
facilitated by the juncture angle a which enables shank 28 to
easily slide through entrance D' as pointed tip 24 is pulled parallel
to the longitudinal axis of second vascular tissue section E'.
More importantly, it has been found that by forming juncture angle
a with an optimal angle of about 45.degree., shank 28 easily and
atraumatically slips through entrance hole D'.
As shown in FIG. 14, once shank 28 has been drawn through entrance
hole D', length of suture material 40 passes through entrance
hole D'. Continued pulling of pointed tip 24 by needle holder
36 parallel to second vascular tissue section E' thereby draws
length of suture material 40 into and through lumens C' and G'.
To draw surgical needle 20 out of lumen G' in second vascular
tissue E', surgical needle 20 is drawn parallel to second vascular
tissue section E' as shown in FIG. 15. Again, juncture angle a
enables shank 28 to easily slip through exit hole I'with minimal
trauma thereto. As specifically shown, the height "H"
of the space adjacent vascular tissue section E' is significantly
less than that of height h illustrated in FIG. 10 with respect
to prior art surgical needle 10 hereinabove.
FIGS. 15 and 16 illustrate, in side-by-side comparison, the significant
differences in operating space required adjacent vascular tissue
sections E, E' in order to manipulate prior art surgical needle
10 and novel surgical needle 20.
It will be understood that various modifications may be made
to the embodiments disclosed herein. For example, the surgical
needle may have a varying or constant radius of curvature as well
as a straight or an arcuate shank. Additionally, alternate methods
of suture attachment are also contemplated. Therefore, the above
description should not be construed as limiting, but merely as
exemplifications of preferred embodiments. Those skilled in the
art will envision other modifications within the scope and spirit
of the claims appended hereto.
A curved surgical needle which may be helical or planar and in
which the curvature may be constant or varied with the pointed
end offset from the principal longitudinal axis.
Inventors: Troutman, Richard C.;
Claims:
I claim:
1. A surgical needle comprising a curved body portion terminating
in one direction in a blunt end and in the other direction in
a pointed end section, said pointed end section being laterally
offset from said curved body portion, said curved body portion
and said pointed end section together forming substantially no
more than 180 degrees of arc and said pointed end section is offset
5 degrees to 60 degrees.
2. A needle according to claim 1 wherein the axis of curvature
of one curved body portion is offset from the axis of curvature
of another body portion 5 degrees to 60 degrees.
3. A needle in accordance with claim 1 wherein a portion of said
curved body portion forms a portion of a helix formed by said
portion with another body portion of said needle.
4. A needle in accordance with any of claims 1 or 3 in which
a portion has a flattened surface formed on the side facing the
axis of curvature of said portion.
5. A surgical needle in accordance with any of claims 1 or 3
in which said offset is 15 degrees to 30 degrees.
6. A surgical needle in accordance with any of claims 1 or 3
in which the radius of curvature of each portion is constant.
7. A surgical needle in accordance with any of claims 1 or 3,
in which the radius of curvature of at least two portions differ
the one from the other.
8. A surgical needle in accordance with any of claims 1 or 3,
in which the radius of curvature of a portion proximal to the
said pointed end is shorter than the radius of curvature of a
portion more distal to said pointed end.
9. A needle according to claim 2 wherein said pointed end is
offset a distance in the range of 0.010" to 0.040" at
its termination.
10. A needle in accordance with claim 9 in which the length of
the pointed end section is offset about 5% to 20% of the curved
length of the curved body portion of said needle.
Description:
BACKGROUND OF THE INVENTION
The present invention relates to surgical needles and more particularly
to specially curved surgical needles especially advantageous for
use in opthalmic microsurgery, and other microsurgery and the
like.
Surgical needles can be any of a variety of shapes ranging from
straight, to ski-shaped to curved. Curved needles are essential
to most surgical procedures involving delicate or fine tissue
to accurately locate the suture loop with a minimum of trauma
to the tissue. To insert a curved needle, the surgeon must grasp
the shaft of the needle with a needle holder at a point generally
near the center of the needle or toward its butt to engage the
tip in the tissue near the edge of the incision or wound. Then
the suture is passed through the tissue and turned to pass through
the tissue on the opposite side of the incision or would by a
semi-rotational movement of the surgeon's fingers, wrist and forearm.
The curvature of the needle helps establish for the surgeon the
desired "bite " while the arcs of rotation of the surgeon's
wrist and forearm or, more precisely, the arc of rotation of the
needle holder held by the surgeon, establish the angulation (non-radiality)
or non-angulation (radiality) of the suture across the incision
or wound.
It is extremely important in certain microscopic surgery involving
fragile tissue, such as in eye surgery or in anastomosis or other
connection of fragile vessels or tubes, that the geometry of the
path of the needle placing an appositional suture be uniform so
as not to exert unequal or contrary forces parallel or tangential
to the edge of the incision or would when the suture loop is formed
and tied. This is important not only with individual (non-continuous)
suturing but also when suturing using multiple continuous bites.
For example, in a corneal transplant a continuous suture is made
to define a series of isosceles triangles, so as not to induce
undesirable rotative force between graft and recipient cornea.
Curved surgical needles, according to prior art construction,
are curved in a single plane. As a surgeon observes them, particularly
when through a vertically directed surgical microscope, and seeks
to establish and maintain a precise arc of rotation for needle
placement, he or she must be able to observe the location of the
needle and when possible its point at all times during passage.
To do this requires either that the head or visual axis be moved
somewhat to one the side, impossible under a powerful microscope,
or, alternatively, to tilt the plane of curvature of the needle,
thereby altering the direction of penetration of the needle in
the tissue.
PRIOR ART
The prior art shows various curved needles of the type to which
the subject invention can be applied, such as U.S. Pat. No. 3,394,704
Dery showing a needle curved in a single plane, and to the same
effect to Kurtz U.S. Pat. Nos. 2,869,550 and 3,094,123, as well
as the application of myself and Walter McGregor, Ser. No. 437,419
now U.S. Pat. No. 4,524,771 incorporated herein by reference and
the art cited therein.
A helical needle whose helix passes through more than 360 degrees
is shown in the 1972 edition of Zentralblatt fur Chirurgie in
Vol. 15 starting at page 480. The purpose here is to enable rapid
closure of a large wound. The helical needle is never disengaged
from the tissue being sutured and hence a surgeon there does not
have to continuously grasp a suturing needle. The helical needle
of said Zentralblatt curves through more than 360 degrees of helix.
SUMMARY OF THE PRESENT INVENTION
The needle in accordance with the present invention is formed
so that while its curvature has one or more radii, the curve is
not in one plane but, to the contrary, is at an angle to any plane
positioned at right angles to an axis of curvature or, alternatively,
the pointed tip is offset so that the tip is visible to a surgeon
viewing the needle from above as through a surgical microscope.
Additionally, any flat portion of the needle on the inside of
the curve, which aids the surgeon to grasp the needle more firmly
than a rounded surface, is rotated or torqued as the needle curves
so that its surface always faces and is parallel to the axis of
curvature. This improvement may be applied to needles of constant
curvature as well as to the compound curved needle shown and claimed
in my patent with Walter McGregor, supra. The angle between a
body portion of the needle and a plane normal to an axis of rotation
may be useful from 5 degrees to 60 degrees. In a preferred embodiment,
particularly useful in opthalmic surgery, I have found angles
of 15 degrees to 30 degrees most useful.
In use, a surgeon grasps the needle with the needle holder at
the appropriate shaft position for that needle curvature and inserts
the point into the tissue to begin the 37 bite" into the
tissue on, for example, the distal side of the incision. He or
she begins penetration driving the needle tip downward through
the tissue while in microsurgery looking down through the microscope.
The view of the needle tip and transparent corneal tissue is not
blocked by the shaft of the needle or by the needle holder enabling
the surgeon to precisely guide the point visually through the
entire bite. As the needle is rotated to engage the opposite side
of the incision, the axis of rotation of the needle holder remains
parallel to the axis of curvature of the needle. The linear offset
of the tip of the needle from the body of the needle permits a
continuous view of the needle tip without the necessity of lateral
displacement of the surgeon's head (impossible in microsurgery).
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1a is a preferred embodiment showing a compound curved needle
formed as part of a helix illustrating the offset tip in accordance
with the invention;
FIG. 1b is a side view of FIG. 1a.
FIG. 2 is a cross-sectional view taken on line 2--2 of FIG. 1b;
FIG. 3 is a cross-sectional view taken on line 3--3 of FIG. 1b;
FIG. 4 is a cross-sectional view taken on line 4--4 of FIG. 1b;
FIG. 5 is an embodiment showing a constant curved needle in one
plane with the alternative offset tip end;
FIG. 5b is a side view of FIG. 5a;
FIG. 6a shows a perpendicular or radially placed stitch closing
a linear incision. This is to be avoided in light or fragile tissue
since such a stitch induces displacement of opposing wound edges.
FIG. 6b shows the preferred "isosceles" stitch (limited
movement of force) which avoids linear displacement of opposing
wound margins;
FIG. 7a illustrates an undesirable continuous stitch in a circular
corneal transplant comparable to the stitch in FIG. 6a and
FIG. 7b illustrates the preferred continuous "isosceles"
in a circular corneal transplant comparable to the stitch in FIG.
6b.
FIG. 8 is a front elevation of a needle formed as part of a helix
showing an offset tip.
DETAILED DESCRIPTION
Referring to the drawings, FIGS. 1a and 1b show a preferred compound
curved surgical needle 20 in accordance with my invention to which
is secured the suture 22. The needle has a straight pointed end
section 24 adjacent a curved body portion 26 with subsequent body
portions 28 of reducing curvature (increasing radius of curvature).
The cross-sectional shape at sections 24, 26 and 28 are shown
in FIGS. 2, 3, and 4, respectively. As can be seen from FIG. 1a,
the point 24 is offset from the body portion 28 and to a progressively
lesser extent from body portion 26. The helical angle between
the axis of the helix (axis of curvature of the helix); and a
body portion is preferably 15 degrees to 30 degrees but may in
some instances be as little as 5 degrees and as great as 60 degrees.
In a needle in which the pointed end section 24 triangular in
cross-section (FIG. 3) is 0.05" the offset would be nominally
0.025" with a range of 0.010" to 0.040" . The needle
may be provided with a flattened surface or face 36 which in any
portion faces the axis of concavity of the curvature.
As illustrated, the needle 20 has an offset tip 24 and a body
portion of successively increasing radii of curvature proceeding
from tip 24 through portions 26 and 28, as more fully described
in the above-mentioned Troutman et al patent incorporated herein
by reference. As illustrated in FIG. 1b, the axis of curvature
of each helical body portion 26,28 is co-axial although the radius
of curvature is different. It should be noted that in the subject
invention the offset may begin at any point along the body portions.
FIG. 5a illustrates an embodiment of my invention which incorporates
the features in a needle of constant curvature. A needle of the
same length but of compound curvature requires less offset than
a needle of constant curvature because the chord 25a is longer
than chord 25b and the grasping point of the compound curved needle
is more distal from the needle point. The grasping point is normally
located from the tip two-thirds the distance from tip to butt
as opposed to the center as in a needle of constant curvature.
Needle 21 has a tip section 40 offset from the longitudinal axis
of the needle. The sections 42, 44 and 46 as illustrated are of
constant radii. These sections, however, may optionally be offset
in the manner illustrated for the tip 40 so that the offset is
obtained by a more gradual but irregular helix.
These needles may be manufactured by any of the methods well
known in the art of needle manufacture. In general, the form of
the needle may be best understood by bending the wire from which
the needle is formed around a mandrel whose surface contains the
desired curves. For example, to make the needle 21 illustrated
in FIGS. 5 and 5b a mandrel of constant diameter would be employed
and the needle would be offset by being placed in a spiral curve
which is cut in the mandrel and has a cross-sectional area and
shape corresponding to that of the needle. The spiral would form
with a plane normal to the axis of the mandrel an angle corresponding
to the desired angle. In the case of the needle of FIGS. 1a, 1b,
a tapered mandrel would be employed with a spiral curved as described
above.
The taper would supply the decreasing radii for the several sections
of needle 20. It is important that the gentler curve be placed
in the wire first and then more tightly curved in the continuous
operation. As clearly shown in the drawings, needles in accordance
with my invention do not exceed 360 degrees and preferably are
less than 180 degrees arc curvature.
FIGS. 6a and 7a illustrate radially placed continuous suturing
stitches, generally not desirable for lighter or fragile tissue.
The length of the external suture limb EL has a greater angle
with respect to the incision 50,60 than does the internal (in
the tissue) suture limb HL. This causes a larger force vector
52 of the externalized limb of stitch EL parallel to the incision
50,60 than does the force vector 54 of the perpendicular internal
stitch HL. Consequently, the tissues to each side of the incision
50,60 are drawn in contrary and unequal sliding motions as illustrated
by the two unequal force vectors 52 and 54 exerted by the external
limb EL and the internal limb HL, respectively. This not only
delays healing but also can cause a displacement at the locations
56 and 58. In the case of eye surgery this induces optical distortions
of the cornea.
A stitch illustrated in FIGS. 6b and 7b in which the internal
stitch HL and the external stitch EL are of equal length, form
the same angle with the incision 50a, 60a and cancel out the sliding
motion caused by vectors of unequal magnitude. It will be noticed
that the lines of the continuous stitch form a series of isosceles
triangles and that is what is meant in this patent application
when the term isosceles stitch is employed. Individual radially
placed or perpendicularly placed interrupted sutures such as illustrated
on Plate 6-13 at p. 188 of Microsurgery of the Anterior Segment
of the Eye, Vol. 1, pp. 188 through 195 can be used alternatively
and their placement is similarly advantaged.
It should be obvious to one skilled in the art that in all instances
direct visualization of the offset needle point during needle
passage facilitates the accurate placement of both individual
and continuous sutures essential to anatomical (and, in the case
of eye surgery, optical) precise would apposition.
I have illustrated in FIGS. 1a and 1b a compound curved surgical
needle formed as a helix in accordance with this invention. The
needle of constant curvature shown in FIGS. 5a and 5b could, of
course, be made helical as in the needle illustrated in FIGS.
1a and 1b. In fact, the compound curvatured needle formed as a
helix to obtain the offset is my preferred embodiment. However,
I have shown the needle 21 in a non-helical form to illustrate
that the offset may be obtained by offsetting the point. It should
be understood that an irregular helix is also within the purview
of my invention. Thus, FIGS. 5a and 5b illustrate other embodiments
of my invention with my preferred embodiment illustrated in FIGS.
1a, 1b.
If desired, the tip of FIG. 5a could be used with the helix of
FIG. 1a as shown in FIG. 8. Also both the compound curve and constant
curve can selectively be formed on a helix or in one plane to
an offset tip. My preferred embodiment for the more rigid tissue
encountered in corneal surgery is the compound curve needle formed
on a helix to provide the offset tip.
Surgical Needle Insertion and Radioactive Seed Implantation:
Simulation and Sensitivity Analysis
Abstract:
To facilitate training and planning for surgical procedures such
as prostate brachytherapy, we are developing new models for needle
insertion and radioactive seed implantation in soft tissues. We
describe a new 2D dynamic FEM model based on a reduced set of
scalar parameters such as needle friction, sharpness, and velocity,
and a 7-phase insertion sequence where the FEM mesh is updated
to maintain element boundaries along the needle shaft. The computational
complexity of our model grows linearly with the number of elements
in the mesh and achieves 24 frames per second for 1250 triangular
elements on a 750Mhz PC. We use the simulator to characterize
the sensitivity of seed placement error to surgical and biological
parameters. Results indicate that seed placement error is highly
sensitive to surgeon-controlled parameters such as needle position,
sharpness, and friction, and less sensitive to patient-specific
parameters such as tissue stiffness and compressibility.
Simulation of needle insertion based on an ultrasound image of
a human prostate cancer patient. Frame (a) outlines the prostate
(in green) and the target implant location (small white dot) which
is fixed in the world frame. Our simulation places a radioactive
seed (large green disc) at this location (d). After needle extraction
and tissue retraction, the placement Error, the distance between
the target and resulting seed location shown in (f), is 30% of
the width of the prostate. Needle plans that compensate for tissue
deformation can reduce placement errors like these that damage
healthy tissue and fail to kill cancerous cells.
Introduction:
Human surgery is increasingly based on minimally invasive techniques
that operate inside the body through narrow openings, reducing
disturbance to healthy tissue, minimizing risk of infection, and
speeding recovery. A fast and accurate computer simulation of
this type of surgery can facilitate surgeon training, optimize
surgical procedures before the patient enters the operating room,
and assist in real-time re-planning during surgery as data is
collected.
Brachytherapy, a type of minimally invasive surgery, allows surgeons
to insert radioactive seeds into cancerous tumors. It is usually
applied to treat prostate cancer. The post-procedure radioactive
dose distribution should minimize healthy tissue damage while
maximizing the destruction of cancerous tissue. Normally, a seed
placement plan is created by a dosimetrist who gives the surgeon
relative coordinates for seed implantation within the prostate.
Multiple seeds and biodegradable spacers are loaded into a needle
that the surgeon inserts horizontally into the patient. Seeds
and spacers are ejected from the needle when the depth specified
by the dosimetrist is reached. Unfortunately, inserting and retracting
a needle in soft tissues causes the tissues to deform: ignoring
these deformations during the implantation results in misplaced
seeds. A dynamic simulation model can facilitate surgery planning
by allowing a surgeon or optimizing planner to determine how surgeon-controlled
parameters and patient-specific parameters will affect seed placement.
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