Localization needle assembly

A localization needle assembly includes an outer tubular cannula and a reinforced needle structure slidably mounted for movement within the outer cannula between extended and retracted portions, the needle structure includes a rearwardly extending retractable barb and a non-retractable barb which are contained within the outer cannula when the inner needle structure is extended while the surgeon locates a lesion. When the target area is reached, the inner needle structure is retracted, and the retractable barb is deployed through an opening in the sidewall of the outer cannula for anchoring the localization needle assembly in body tissue in the proximity of the lesion. When positioning is satisfied with precise targeting of the lesion, the outer cannula is removed, leaving both the fixed and retractable barbs in place with both barbs deployed and localizing the lesion to be removed for biopsy procedure.

BACKGROUND OF THE INVENTION 
The present invention relates to a novel localization needle assembly which 
may be readily inserted into and anchored within body tissue to identify 
to the surgeon the location of nonpalpable lesions. 
Various localization needle systems have been proposed to aid the surgeon 
in locating nonpalpable lesions within the breast. In one system commonly 
referred to as a needle and hook-wire system, a hypodermic needle is 
initially placed into the breast to locate the breast lesion. When the 
needle is properly placed, a stainless steel wire having a hairpin 
hooked-end portion is slid through the needle wherein the hooked 
hairpin-end portion exits from the needle to engage the body tissue to 
retain the needle adjacent to or at the breast lesion. The introducing 
needle is withdrawn over the wire and the wire is anchored to the tissue 
and the patient is taken to surgery. The wire permits the surgeon to 
locate where the lesion lies within the breast tissue. 
However, this needle and wire-hook arrangement possesses several 
disadvantages. For example, during mammographic filming of the breast 
lesion and the location of the needle within the breast, the breast is 
compressed and this can cause the needle to move or be displaced with 
respect to the breast lesion. Additionally, when the needle and 
hairpin-end hook wire has been inserted through the needle and expanded to 
anchor the needle/hook-wire apparatus in place in the fatty tissue within 
the breast, oftentimes this fatty tissue does not provide sufficient 
anchoring and/or stability to needle/hook-wire apparatus to permit 
completion of the medical procedure on the patient. Such migration of the 
assembly can lead to the failure to adequately complete the removal of 
non-palpable lesions without undue delay and repositioning procedures. 
Another needle/wire device and technique includes a curved-end wire which 
is made of a tough pseudo-elastic alloy which possesses a memory. A needle 
containing a wire having a J-shaped hook on the end is inserted into the 
breast and advanced to identify the location of the breast lesion. The 
wire is then advanced inwardly such that the curved hooked end engage the 
body tissue to immobilize the needle during mammography imaging to insure 
that the needle is correctly positioned at or adjacent the breast lesion. 
The needle and hook device can be relatively easily displaced if traction 
or pressure is applied to the breast during transport of the patient or 
during surgery. Thus, actual migration of the hook-wire device in the 
fatty tissue of the breast occurs during surgery and movement of the 
patient to surgery. Such migration of the assembly can lead to the failure 
to adequately complete the removal of non-palpable lesions without undue 
delay and repositioning procedures. 
Both of those systems employ a single wire needle for anchoring the 
localization needle assembly to body tissue. The wire needle must be 
flexible and pliable to allow easy handling and fastening of the proximal 
end of the wire outside of the patient's body and to resist the risk of 
unintended penetration or migration. However, because the needle wire must 
be sufficiently large so as to resist migration and accidental transection 
by the surgeon during excision, this limits the amount of flexibility and 
pliability obtainable for known needle anchoring arrangements which employ 
a single wire. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a new and 
improved localization needle assembly for use in locating and pinpointing 
lesions within a body. 
Another object of the present invention is a novel localization needle 
assembly which may be readily positioned and locked within body tissue to 
precisely locate an pinpoint lesions for subsequent surgical removal or 
biopsy. 
A further object of the present invention is a novel localization needle 
assembly which includes a retractable anchoring means located within a 
cannula, which is adapted to be extended outwardly from the side wall of 
the cannula to lock and anchor the localization needle assembly to the 
body tissue, and a fixed anchoring means located at the distal end of the 
inner cannula to precisely locate lesions within the breast for subsequent 
surgical removal. 
It is yet another object of the present invention to provide a novel 
localization needle assembly including a needle structure having a 
rearwardly retractable barb means and a non-retractable barb means for 
fixedly anchoring the localization needle assembly within the fatty tissue 
of the breast. 
Still another object of the present invention is a needle structure for a 
localization needle assembly which is characterized by greater flexibility 
and pliability than that for known comparable sized needles and which 
resists accidental transection. 
These and other objects are achieved by the present invention which 
provides a localization needle assembly for locating lesions within body 
tissue, including in combination: an outer tubular cannula member having a 
distal end and a proximal end with the cannula member having an opening 
predeterminedly located from the distal end, an elongated inner needle 
structure having a distal end terminating in a distal tip portion and a 
proximal end, the needle structure having anchoring means including a 
first barb located at the distal tip portion and a second barb located 
proximal of the distal tip portion, the inner needle structure being 
slidably mounted for movement within the outer cannula member between 
first and second positions, the second barb being contained within the 
outer cannula member, extending towards the opening in the outer cannula 
member when the needle structure is in the first position and the second 
barb being moved outward of the outer cannula member through the opening 
predeterminedly located from the distal end of the outer cannula member to 
engage body tissue when the needle structure is moved to the second 
position to anchor the localization needle assembly to body tissue, and 
both of the barbs being deployed to engage body tissue with subsequent 
movement of the cannula member relative to the inner needle structure in a 
direction toward the proximal end of the inner needle structure. 
With these and further objects of the present invention, the nature of 
which will become more apparent, the invention will be more fully 
understood by reference to the drawings, the accompanying detailed 
description and the appended claims.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring to FIG. 1, there is illustrated a localization needle assembly 10 
provided in accordance with the present invention for use in locating 
lesions within body tissue, and in particular for use as a breast 
localization needle assembly for locating nonpalpable lesions within the 
breast. Although the localization needle assembly 10 is specifically 
described with reference to an application as a breast localization 
assembly, the localization needle assembly 10 of the present invention has 
application in locating cancerous nonpalpable lesions within the human or 
animal body, be it a brain tumor, or any medical procedure which requires 
the pinpointing of a lesion, foreign body or normal structure within the 
body or organ of the body. 
The localization needle assembly 10 includes a tubular outer cannula 11 and 
a needle structure 12 which is adapted for sliding movement within the 
outer cannula 11. The needle structure 12 defines a retractable barb 13, 
shown deployed in FIG. 1, whereby the barb 13 projects outward through an 
aperture 14 in the outer cannula 11 for anchoring the localization needle 
assembly to body tissue as will be described hereinafter. The barb 13 is 
retracted within the outer cannula 11 during introduction of the needle 
guide assembly into the patient's body during localization procedures, and 
is deployed by withdrawing the wire structure by pulling on its proximal 
end for immobilizing the needle during mammography. 
The needle structure 12 has markings 29 and 29a thereon to provide an 
indication to the user as to the location of the tip and barb relative to 
the tip and aperture (FIG. 1) of the cannula 11. The markings enable the 
surgeon to know when the barb is retracted and when it is deployed. For 
example, marking 29 when aligned with the proximal edge 11a of the cannula 
indicates that the barb is retracted within the cannula 11. The marking 
29a, when aligned with the proximal edge 11a of the cannula 11, indicates 
that the barb is fully deployed. 
Referring to FIG. 2, the needle structure 12 has a proximal end 14' and a 
distal end 15. The needle structure 12 is formed of an elongated single 
wire 16 which is reinforced over a portion of its length with multiple 
wire strands 17 to form a unitary needle wire structure. As illustrated in 
FIG. 2, for example, the outer wires 17 may be wound (or stranded) in 
helical fashion around the core wire 16, but terminate short of the distal 
end of the core wire 16 defining a junction point 18 at which point the 
outer wires 17 are connected or secured to the core wire 16 in a suitable 
manner such as by solder or welding. A further solder joint 19 is provided 
at the tip of the needle structure 11 at the proximal end 14.degree. 
thereof. These solder connections protect the wire 11 from fraying at the 
proximal end 14' and at the junction 18. 
The distal tip portion of the core wire 16 is bent over on itself and 
tightened, as is known in the art, to form the barb portion 13 which 
projects rearwardly from the distal tip, that is, toward the right in FIG. 
2, and terminates in a sharp tip or point 20. The overbend may be secured 
as by solder 20a. The use of reinforcement permits the needle structure 12 
to be made of a smaller diameter wire to enhance the flexibility and 
pliability of the needle structure without compromising its resistance to 
accidental transection. 
For the needle structure 12 illustrated in FIG. 2, the reinforcement is 
provided by the multiple wire strands 17 which may be wound or stranded on 
the core wire 16 over a portion of its length. The outer wires 17 may be 
wrapped on the core wire 16 and/or may be braided before being combined 
with the core wire. Moreover, although wires of circular cross-section are 
illustrated, the outer wire or wires could be in the form of a flat band 
or strip having a rectangular cross-section. Also, although the core wire 
16 illustrated in FIG. 2 is a single wire element, the core wire may 
comprise a two element structure 30 such as that illustrated in FIG. 3 
wherein an inner cannula 33 is secured to the distal end of the core wire 
16 as will be described. Further, as illustrated in FIG. 4, the 
reinforcement for a needle structure 40 is provided by coiling the core 
wire over a portion of its length as will hereinafter be described. 
The stranded needle structures 12 and 30 illustrated in FIGS. 2 and 3 may 
take various forms. Referring to FIG. 5, by way of example, the needle 
wire structure 12 may comprise a core wire 16 on which may be wound or 
stranded a plurality of outer wires 17, there being twelve wires 17 
illustrated in FIG. 5. 
Referring to FIG. 6, in a further embodiment, the needle structure 12a 
includes twelve outer wires 22 wrapped around six intermediate wires 23 
wrapped around a single core wire 16. In FIG. 7, a needle structure 12b 
includes a single core wire 16 upon which are wrapped six strands 24 each 
including seven wires 25. In another embodiment for a wire structure 12c 
shown in FIG. 8, the core 16' comprises a stranded wire including three 
wires 27 upon which are wound or stranded nine outer wires 28. 
The stranded configuration for the needle structure 12 provides 
reinforcement for the needle structure along substantially its entire 
length providing many advantages over a conventional wire needle. For 
example, multiple strands resist accidental transection. Even if several 
strands were to be cut, functionality of the needle structure would be 
preserved. Also, strands are more flexible than stiff single wires and the 
use of strands reduces risk of additional penetration of organs or vessels 
or migration within cavity due to accidental contact with the needle 
assembly during normal movement of the patient during diagnostic 
procedures as during the transportation of the patient to surgery. The 
flexibility and pliability allow easier handling of the wire structure 
outside of the patient's body and fastening of the wire structure to the 
patient's skin with adhesive tape. Moreover, a larger strand has greater 
tensile strength than a single small diameter wire, and a strand resist 
fatigue breakage better than does a single wire. 
Referring to FIG. 3, there is illustrated a further embodiment for a 
stranded needle structure 30 having a proximal end 31 and a distal end 32 
and which includes a short inner cannula member 33 which is attached to 
the core wire 16 at its end 35. The needle structure 30 further includes a 
short wire member 36, the forward end 36a of which is secured to the inner 
cannula member 33 by soldering, welding, by adhesive or by mechanical 
means, such as, crimping, threading or shrinking. The short wire member 36 
includes a free end 37 defining a barb or hook which is adapted to anchor 
the needle within body tissue. 
Referring to FIG. 4, a further embodiment of a needle structure 40 includes 
a linear portion 41 at its distal end 42 and a helical portion 43 
intermediate its proximal end 44 and its distal end 42, and preferably 
extending all the way to its proximal end. The needle structure 40 may be 
formed of a single wire or monofilament which is coiled from the linear 
portion 41 to its proximal end. The tip of the wire is folded back upon 
itself to define a rearwardly projecting barb 45. 
The helical coiled portion 43 defines the reinforcement for the needle 
structure 40 while permitting use of a single wire or monofilament. This 
configuration provides a degree of rigidity of the needle structure in the 
distal end portion, permitting the barb to anchor the localization needle 
assembly to body tissue, and with the proximal end portion or helical 
coiled portion 43 providing flexibility and pliability in the portion of 
the structure by which the user directs the anchoring distal end to the 
target. 
Referring to FIG. 9, the outer cannula 11 includes a hollow tubular shaft 
portion 51 having a proximal end 52 and a distal end 53. The cannula may 
be comprised of a rigid material composed of either steel, polymer or a 
combination thereof and may be of a variable length as required. A hub 54 
is mounted on the proximal end of the shaft 51 to facilitate use of the 
cannula. The distal end 53 is provided with a sharp point 55. The tubular 
shaft 51 has an opening 14 formed therethrough at a predetermined distance 
from the tip 55 of the cannula. Markings 58 are provided on the outer 
surface of the cannula 11 to provide an indication to the surgeon of the 
depth to which the cannula has been inserted into the body of the patient 
being treated. 
The use of the needle guide assembly provided by the present invention is 
described with reference to an embodiment for the needle guide assembly 60 
illustrated in FIGS. 10 and 11 which includes the needle structure 30 
illustrated in FIG. 3 and the outer cannula 11 illustrated in FIG. 7. 
However, the needle structures 12 and 40 illustrated in FIGS. 2 and 4, 
would function in a similar manner in localization procedures. 
Referring to FIGS. 10 and 10A, there is illustrated a needle guide assembly 
60 which includes the needle structure 30 assembled with the cannula 11. 
In FIGS. 10 and 10A, the barb 36 is illustrated in the retracted position. 
In the retracted position, the barb 36 is located within the bore 57 
forward of the opening 14 with the barb 36 engaging the inner wall 59 of 
the tubular shaft 51. 
Referring to FIGS. 11 and 11A, the needle guide assembly 60 is illustrated 
with the barb 36 in the extended position wherein the needle wire 
structure 30 has withdrawn back into the cannula 11, moving the inner 
cannula 33 towards the right in FIGS. 11 and 11A, permitting the barb 36 
to pass through the opening 14 in the cannula 11 for deployment. 
In use, referring to FIGS. 10 and 10A, initially, the needle structure 30 
is positioned within cannula 11 so that the tip of the needle structure 30 
extends outwardly of the cannula 11 at the distal end 53 of the cannula 11 
such that the barb 36 is retracted during insertion of the assembly into 
the tissue of the body. 
The localization needle assembly 60 is advanced to the target area of a 
human or animal body, either for simply marking the location, be it the 
breast, liver, ductal structure, brain, lung or other organs where it is 
desirable to take a biopsy, a sample structure or to surgically remove an 
unwanted mass or lesion from the body. The desired position is obtained by 
advancing the needle assembly into the target area using the forward 
pressure on the hub on the cannula 11 to advance the localization needle 
assembly 60 into the target. After the needle has been properly positioned 
using either X-ray, ultrasound, or other imaging means, the inner needle 
assembly 30 is withdrawn back into the cannula thereby deploying the barb 
member 36 through opening 14 in the sidewall of the cannula 11 to lock and 
firmly anchor the localization needle assembly 60 in position within the 
body tissue, immobilizing the assembly 60. When the localization needle 
assembly 60 has been inserted into the breast, the movement of the barb 
member 36 into the body tissue anchors and firmly retains the needle 
assembly within the breast or body tissue. The opening 14 may be located 
on the outer cannula at a position where it is desired that the needle 
assembly be anchored to the body tissue. Preferably this position is 
adjacent the distal end, but it could be located at any position 
intermediate the distal and proximal ends provided proper anchoring of the 
localization needle assembly occurs with respect to the body tissue. 
If after deployment of the barb 36, it is determined by X-ray, ultrasound 
or filming means, that the localization needle assembly has not located a 
lesion, the barb 36 can be retracted by advancing the stranded needle and 
the inner cannula attached thereto into the outer cannula 11. The 
localization needle assembly 60 can then be repositioned to locate the 
lesion, the inner cannula 33 being moved outwardly of the outer cannula 11 
to again deploy the barb 36 when the lesion is located. 
As is well known in the art, the length of the outer cannula can vary 
depending upon the depth of the lesion that is to be localized and 
identified for subsequent surgical operation. 
Referring to FIGS. 12-14, there are illustrated further embodiments for the 
needle structure 12', 80 and 80' which include dual anchoring means 
including two barbs. One barb 13 at the distal tip of the needle structure 
is a fixed barb. The other barb 36, located proximally of the distal tip 
of the needle structure, is a retractable barb. The retractable barb is 
adapted to lock and anchor the localization needle assembly to body 
tissue. The fixed barb is located at the distal tip of the needle 
structure to precisely locate lesions within body tissue. Needle structure 
12' is similar to needle structure 12 illustrated in FIG. 2 and 
accordingly corresponding elements have been given like reference 
numerals. Similarly, needle structures 80 and 80' are similar to needle 
structure 30 illustrated in FIG. 3, and corresponding elements have been 
given like reference numerals. 
Referring to FIG. 12, in needle structure 12', the fixed barb 13 is formed 
at the distal tip of the core wire 16. The retractable barb 36 projects 
rearwardly from a point just behind the distal tip and terminates in a 
sharp tip or point 36'. The barb 36 is attached to the core wire 16 in a 
suitable manner as by welding or soldering 20a' at its base portion 36a. 
In FIG. 12, the retractable barb is shown located approximately 
180.degree. circumferentially from the fixed barb 13. It has been found 
that this arrangement minimizes lateral shifting of the needle structure 
12' when the same has been positioned and anchored within the body tissue. 
However, in some applications it may be desirable to have both barbs 
located along a common axis in the same plane, i.e., aligned along one 
side of the core wire 16 or have one of the barbs extending in any 
direction with respect to the other barb to provide enhanced anchoring of 
the assembly. The needle structure 12'includes a flexible reinforced 
portion according to any of the embodiments disclosed herein. For example, 
the reinforced portion may be formed by multiple wires 17 wound as 
illustrated in FIGS. 5-8, or the flexible reinforced portion may be a 
helical coiled section of a monofilament. Moreover, in some applications 
the core wire 16 may not have a reinforced portion. Needle structure 12' 
is used with the outer cannula 11 as described above. 
Referring to FIG. 13, the needle structure 80 is similar to needle 
structure 30 illustrated in FIG. 3 and includes a short inner cannula 
member 33 which is attached to the core wire 16 near its distal end 35. In 
the needle structure 80, the core wire 16 extends through the inner 
cannula member 33 and has its distal end portion 16a portion extending out 
through the forward end 33a of the inner cannula member 33 through an 
opening (not shown). The distal end portion 16a of the core wire 16 is 
bent over on itself and tightened, as is known in the art, to form the 
fixed barb portion 13 which projects rearwardly from the distal tip, and 
terminates in a sharp tip or point 20. The over bend may be secured as by 
solder 20a. The barb 13 is located 180.degree. circumferentially from the 
retractable barb 36. Barb 36 comprises a short wire member the forward end 
36a of which is secured to the inner cannula member 33 by soldering, 
welding, by adhesive or mechanical means, such as crimping, threading or 
shrinking. As for the needle structure 30, the short wire member 36 
includes a free end 37 defining a barb or hook which is adapted to anchor 
the needle within the body tissue as has been described. 
Referring to FIG. 14, the needle structure 80' is similar to needle 
structure 80, but the fixed barb 13 formed at the distal tip of the needle 
structure 80' comprises a short wire member 82 which is secured to the 
distal tip of the inner cannula member 33 by soldering, welding, adhesive, 
or by mechanical means, such as crimping, threading or shrinking. The 
retractable barb 36 is formed by bending the distal tip of the core wire 
16 over on itself or as a separate short wire segment which is secured to 
the inner cannula 33 in the manner described above for needle structure 
30. 
FIGS. 15, 16 and 16A illustrate various positions for the needle structure 
relative to the outer cannula 11, shown in phantom. FIG. 15 illustrates 
the needle structure position during positioning of the localization 
needle assembly, i.e., while a lesion is being targeted. FIG. 16 
illustrates the needle positioned to provide a temporary anchoring by the 
retractable barb 36 during imaging to confirm that a lesion has been 
precisely located. FIG. 16A illustrates withdrawal of the outer cannula 11 
following confirmation of localizing a lesion whereby both barbs are 
deployed in the body tissue. 
Referring to FIG. 15, the needle structure 80 is illustrated in its 
retracted or undeployed configuration with both the fixed barb 13 and the 
retractable barb 36 extending generally axially of the core wire 16 and 
lying along the core wire 16. The needle structure 80 is illustrated 
positioned within the cannula 11, shown in phantom, with a portion of the 
fixed barb 13 extending slightly beyond and out of the distal end 53 of 
the cannula 11 and with the retractable barb 3 and the inner cannula 33 
located rearwardly of the opening 14 in the cannula 11. 
Referring now to FIG. 16, which is a fragmentary view similar to FIG. 15, 
the needle structure 80 is shown with the retractable barb 36 in its 
deployed or extended condition. The fixed barb 13 is maintained in its 
"folded" or retracted condition by its engagement with the distal end 53 
of the outer cannula. In this position, the inner cannula 33 distal end is 
located forwardly past the opening 14. 
Referring to FIG. 16A, the outer cannula 11 is shown withdrawn past the two 
barbs 13 and 36. Initially, as the outer cannula is withdrawn from the 
position shown in FIG. 16, the tip of barb 13 is released from within the 
distal end of the cannula 11 and the barb 13 flexes outwardly to its 
deployed position. With continued withdrawing movement of the cannula 11 
toward the left in FIGS. 16 and 16A, the retractable barb 36 initially is 
engaged by the cannula 11, and particularly the forward edge 14a of 
opening 14, causing the barb 36 to be retracted into the cannula 11. When 
the distal end of the cannula 11 is moved past the barb 36 to the position 
shown in FIG. 16A, and the barb 36 is out of engagement with the cannula, 
barb 36 flexes outwardly to its deployed position in the body tissue to 
anchor the assembly. 
Referring to FIGS. 17 and 18, needle guide assembly 80 is illustrated 
assembled with the cannula 11. In FIG. 17, both the fixed barb 13 and 
retractable barb 36 are illustrated in the retracted position. When in the 
retracted position, the retractable barb 36 is located within the bore 57 
forward of the opening 14 with the barb 36 engaging the inner wall of the 
cannula 11. In FIG. 18, the needle guide assembly 80 is illustrated with 
the barb 36 in the extended position after the needle wire structure 80 
has withdrawn slightly back into the cannula 11, moving the inner cannula 
33 towards the right in FIG. 18, permitting the barb 36 to pas through 
opening 14 in cannula 11 for deployment. The fixed barb 13 is maintained 
folded over, or nondeployed, by the distal end of the cannula 11. 
In use, referring to FIGS. 17 and 18, initially, the needle structure 80 is 
positioned within cannula 11 so that the tip of the needle structure 80, 
including a portion of folded fixed barb 13 extends outwardly of the 
cannula 11 at the distal end 53 of the cannula 11 and the retractable barb 
36 is retracted within cannula 11. This relative positioning of the needle 
structure 80 and the cannula 11 is maintained during insertion of the 
assembly into the body. The fixed barb 13 is maintained in its folded 
position by the forward distal tip of the cannula 11. Markings 58 are 
provided on the outer surface of cannula 11 to provide an indication to 
the surgeon of the depth to which the cannula has been inserted into the 
body of the patient being treated The manner in which the localization 
needle assembly 80 is advanced to a target area within a human or animal 
body has been described hereinabove. 
Referring to FIG. 18, when the tip of the needle assembly 70 reaches the 
target area, and a lesion is located, the retractable barb 36 is deployed 
to anchor the distal end of the needle assembly while desired positioning 
is confirmed. Markings 29, 29a and 29b on the needle structure 80 indicate 
the position where both barbs are contained within the outer cannula 11, 
the position where the retractable barb 36 is deployed through opening 14 
and the position where both barbs are deployed external to the cannula, 
respectively. Retractable barb 36 is indicated as being retracted when 
marking 29 is adjacent to the proximal end 11a of the handle (FIG. 17) and 
the barb 36 is deployed when the wire structure 80 is withdrawn slightly 
from the cannula 11 until marking 29a is located at the proximal end 11a 
of the handle (FIG. 18). 
When the positioning is satisfied with precise targeting of the lesion, the 
outer needle 11 is removed, leaving the double barb in place with both 
barbs 13 and 36 deployed and localizing the lesion to be removed for 
biopsy procedure. 
The fixed barb 13 defines a fixed anchoring means for the needle structure 
80 and the retractable barb 36 defines a temporary anchoring means for the 
needle structure. Thus, when the needle structure is in place in fatty 
tissue within the breast, and the fatty tissue does not provide sufficient 
anchoring and/or stability to the distally located fixed barb 13, the 
retractable barb 36 supplements the anchoring afforded by barb 13 to 
provide the requisite stability to the needle structure to permit 
completion of the medical procedure on the patient and substantially 
prevents migration of the needle structure. 
Although only a single fixed barb 13 has been illustrated in the drawings, 
it is within the scope of the present invention that a fixed barb may be 
comprised of a plurality of barbs or tissue anchoring elements.