Surgical suture abstract
An apparatus for ultrasonically forming a surgical suture tip from
a length of unfinished surgical suture material. The apparatus includes
a first tipping die having a first face for contacting a portion
of the length of unfinished surgical suture material. A second tipping
die having a second face is also provided. At least one mechanical
actuator is provided for moving the first face of the first tipping
die toward the second face of the second tipping die. A second actuator
vibrates at least one of the first and second tipping dies at an
ultrasonic frequency of about 15 KHz to 70 KHz.
Surgical suture claims
What is claimed is:
1. An apparatus for ultrasonically forming a surgical suture tip
from a length of unfinished surgical suture material, comprising:
(A) a first tipping die having a first face for contacting a portion
of said length of said unfinished surgical suture material wherein
the first face has a cutting notch therein;
(B) a second tipping die having a second face;
(C) at least one mechanical actuator for moving said first face
of said first tipping die toward said second face of said second
tipping die; and
(D) a second actuator for vibrating at least one of said first
and second tipping dies at an ultrasonic frequency of about 15 KHz
to 70 KHz.
2. The apparatus of claim 1 further comprising means for tensioning
said length of said unfinished surgical suture material.
3. An apparatus for ultrasonically forming a surgical suture tip
from a length of unfinished surgical suture material, comprising:
(A) a first tipping die having a first face for contacting a portion
of said length of said unfinished surgical suture material;
(B) a second tipping die having a second face;
(C) at least one mechanical actuator for moving said first face
of said first tipping die toward said second face of said second
tipping die; and
(D) a second actuator for vibrating at least one of said first
and second tipping dies at an ultrasonic frequency of about 15 KHz
to 70 KHz wherein said first tipping die is circular and a tipping
groove is positioned around a perimeter of said first tipping die,
wherein said second tipping die is circular and a tipping notch
is positioned around a portion of a perimeter of said second tipping
die, and wherein said at least one mechanical actuator is provided
for turning said first and second tipping dies in order to move
said first face of said first tipping die toward said second face
of said second tipping die.
4. The apparatus of claim 3 wherein said tipping notch has a cutting
notch therein, and wherein said second actuator is further provided
for cutting said surgical suture tip by vibrating said cutting notch
at said ultrasonic frequency.
5. The apparatus of claim 3 further comprising means for tensioning
said length of said unfinished surgical suture material.
Surgical suture description
FIELD OF THE INVENTION
The present invention is directed to systems for processing strings
and yarns. More particularly, the present invention is directed
to automated systems for forming surgical suture tips through the
use of ultrasonic welding.
BACKGROUND OF THE INVENTION
Various automated systems for forming and cutting surgical suture
tips exist or are known in the art. In one such machine, means for
simultaneously advancing in parallel at least six separate strands
of suture material, and six independent tensioners for maintaining
respective parallel portions of each of the six strands at a preset
tension are provided. Once a predetermined length of suture material
has been advanced by the advancing means, a horizontal heater bar
(positioned perpendicular to the six suture strands) is actuated
by an electronically controlled solenoid which moves a planar heater
bar into contact with one side of the suture strands for a predetermined
dwell time. Once the predetermined dwell time has elapsed, the solenoid
retracts the heater bar to its original position, and the heat exposed
(or heat-stiffened) section of suture material is advanced to a
cutting station. At the cutting station, the heat-stiffened section
of suture material is cut at its midpoint, thereby producing a suture
with two stiffened ends. Other mechanisms for forming and cutting
surgical suture tips are shown in U.S. Pat. Nos. 4832025 4806737
and 5226336 to Coates. The system described in the Coates patents
uses convective or non-contact heating to form suture tips.
Known systems for forming and cutting surgical suture tips suffer
from several drawbacks. First, such systems typically use heat to
stiffen the surgical suture tips. Since the unfinished surgical
suture material used by such systems is often coated, the heat applied
during the tipping process may melt the coating. Once it has melted,
the coating from the unfinished surgical suture material often adheres
to the tipping machine, thereby compromising the machine's performance.
Another drawback of known systems for forming and cutting surgical
suture tips is that such systems typically produce a suture tip
which lacks a substantially uniform cross-section. In addition,
such systems are undesirable in that they typically cut the suture
tip in an imprecise manner, thereby leaving a cut end which may
be irregular or distorted in shape. From a manufacturing standpoint,
suture tips having non-uniform cross-sections and/or irregular or
distorted cut ends are undesirable because, among other things,
such sutures are difficult to insert into needles. Finally, known
systems which use heat to stiffen surgical suture tips are undesirable
because such systems cannot be used with sutures formed from silk.
It is therefore an object of the present invention to provide a
system for forming surgical suture tips which system does not use
heat in forming the suture tips and which may be used to fuse silk.
It is a further object of the present invention to provide a surgical
suture having a welded core which facilitates the easy insertion
of the suture tip into a needle.
It is a further object of the present invention to provide an automated
system and method for manufacturing surgical sutures having tips
with welded cores.
It is a still further object of the present invention to provide
an automated system and method for making surgical sutures with
tips having precisely cut ends.
These and other objects and advantages of the invention will become
more fully apparent from the description and claims which follow
or may be learned by the practice of the invention.
SUMMARY OF THE INVENTION
The present invention is directed to a multifilament surgical suture
having a body portion and a tip portion which is adjacent to the
body portion. The surgical suture is formed of a plurality of filaments.
The tip portion has a tip length, a tip cross-section perpendicular
to the tip length, and a tip core positioned at a center of the
tip cross-section and along the tip length. The filaments positioned
at the tip core are ultrasonically fused together.
In accordance with a further aspect, the present invention is directed
to an apparatus for ultrasonically forming a surgical suture tip
from a length of unfinished surgical suture material. The apparatus
includes a first tipping die having a first face for contacting
a portion of the length of unfinished surgical suture material.
A second tipping die having a second face is also provided. At least
one mechanical actuator is provided for moving the first face of
the first tipping die toward the second face of the second tipping
die. A second actuator vibrates at least one of the first and second
tipping dies at an ultrasonic frequency of about 15 KHz to 70 KHz.
In accordance with a still further aspect, the present invention
is directed to a method for ultrasonically forming a surgical suture
tip from a length of unfinished surgical suture material. The length
of unfinished surgical suture material is positioned at a location
between a first face of a first tipping die and a second face of
a second tipping die. After the positioning step, the surgical suture
tip is formed by vibrating at least one of the first and second
tipping dies at an ultrasonic frequency of about 15 KHz to 70 KHz.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the manner in which the above-recited and other advantages
and objects of the invention are obtained and can be appreciated,
a more particular description of the invention briefly described
above will be rendered by reference to a specific embodiment thereof
which is illustrated in the appended drawings. Understanding that
these drawings depict only a typical embodiment of the invention
and are not therefore to be considered limiting of its scope, the
invention and the presently understood best mode thereof will be
described and explained with additional specificity and detail through
the use of the accompanying drawings.
FIG. 1 is a schematic diagram showing a machine for ultrasonically
forming and cutting surgical sutures, in accordance with a preferred
embodiment of the present invention.
FIG. 2 is a side view of a suture tipping station formed from a
pair of opposing tipping dies one of which is in its retracted position,
in accordance with a preferred embodiment of the present invention.
FIG. 3 is a side view of the suture tipping station of FIG. 2
wherein one of the tipping dies in the station is in its extended
position.
FIG. 4 is an enlarged view of a portion of the suture tipping station
shown in FIG. 2.
FIG. 5 is an enlarged view of a portion of the suture tipping station
shown in FIG. 3.
FIG. 6 shows a cross-sectional view of a length of surgical suture
material which has been ultrasonically fused at its core, in accordance
with a preferred embodiment of the present invention.
FIGS. 7 and 8 show side views of opposing tipping dies for ultrasonically
forming surgical suture tips, in accordance with alternative preferred
embodiments of the present invention.
FIG. 9 is a cross-sectional view of a moving clamp shown in its
closed state for grasping and advancing surgical suture material,
in accordance with a preferred embodiment of the present invention.
FIG. 10 is a cross-sectional view showing the moving clamp of FIG.
9 in its open state, in accordance with a preferred embodiment of
the present invention.
FIG. 11 is a cross-sectional view of a stationary clamp shown in
its closed state for grasping surgical suture material, in accordance
with a preferred embodiment of the present invention.
FIG. 12 is a cross-sectional view showing the stationary clamp
of FIG. 11 in its open state, in accordance with a preferred embodiment
of the present invention.
FIG. 13 is an isometric view of a system for tensioning a length
of surgical suture material, in accordance with a preferred embodiment
of the present invention.
FIG. 14 is an isometric view of an optical detection system for
detecting knots in surgical suture material passing through the
system, in accordance with a preferred embodiment of the present
invention.
FIG. 15 is a further isometric view showing a knot positioned between
the optical source and the optical detector of the knot detection
system of FIG. 14 in accordance with a preferred embodiment of
the present invention.
FIG. 16 is a cross-sectional view of FIG. 15 showing a knot positioned
between the optical source and the optical detector of the knot
detection system of FIG. 14 in accordance with a preferred embodiment
of the present invention.
FIG. 17 is a side view of a suture tipping station formed of opposing
circular tipping dies, in accordance with an alternative preferred
embodiment of the present invention.
FIG. 18 is a cross-sectional view of the suture tipping station
shown in FIG. 17.
FIG. 19 is a side view of a suture tipping and cutting station
formed of opposing circular tipping and cutting dies, in accordance
with a further alternative preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Overall System Operation
Referring now to FIG. 1 there is shown a schematic diagram showing
a machine 10 for ultrasonically forming and cutting surgical sutures,
in accordance with a preferred embodiment of the present invention.
A continuous length of unfinished surgical suture material 110 is
supplied to machine 10 from a supply spool 100 having unfinished
surgical suture material 110 wound thereon. Unfinished surgical
suture material 110 from supply spool 100 is initially advanced
through a tensioning assembly 200 for creating a tension in the
unfinished surgical suture material, and then through a knot detector
system 300 for detecting whether a knot is present in any unfinished
surgical suture material 110 passing through knot detector system
300. After passing through the knot detector system 300 the unfinished
surgical suture material is advanced to a tipping station 400 where
a predetermined length of the unfinished surgical suture material
110 is ultrasonically formed into a length of surgical suture tip
material. After the ultrasonically formed surgical suture tip material
is formed in station 400 the suture tip material is advanced to
a cutting station 450 (e.g., an automated scissor or guillotine
cutter) where the suture tip material is cut, thereby yielding a
finished surgical suture having a body portion formed of unfinished
surgical suture material 110 and an ultrasonically formed tip portion
terminating with a cut end.
As explained more fully below, the unfinished surgical suture material
110 from supply spool 100 is advanced through machine 10 by a moving
clamp 500 which is coupled to a linear actuator 550 for driving
the moving clamp 500 between a starting or home position 510 on
one side of the cutting station 450 and an end position 512 on the
other side of the cutting station 450. Moving clamp 500 has a grasping
(or closed) state shown in FIG. 8 and a non-grasping (or open)
state shown in FIG. 9. In accordance with instructions received
from a controller 800 the moving clamp 500 selectively grasps and
pulls the unfinished surgical suture material 110 through machine
10 in order to facilitate the manufacture of the finished surgical
sutures. In addition to advancing unfinished surgical suture material
through the machine, the moving clamp 500 functions to initially
position and align the unfinished surgical suture material 110 within
the tipping station 400.
During operation of the machine 10 the moving clamp 500 initially
grasps or closes on the unfinished surgical suture material 110
at the home position 510. Next, while the moving clamp 500 remains
in its grasping or closed state, the linear actuator 550 drives
the moving clamp 500 from its home position 510 to the end position
512. As the linear actuator 550 drives moving clamp 500 from its
home position 510 to its position 512 the moving clamp 500 pulls
a length of the unfinished surgical suture material 110 through
the station 400 and through a stationary clamp 600 positioned adjacent
to the end position 512. Like the moving clamp 500 the stationary
clamp 600 has a grasping (or closed) state which is shown in FIG.
10 and a non-grasping (or open) state shown in FIG. 11. As the
linear actuator 550 drives the moving clamp 500 from home position
510 to end position 512 the stationary clamp 600 is in its open
state. After the moving clamp reaches its end position 512 the
stationary clamp 600 grasps or closes on the unfinished surgical
suture material 110 positioned within the stationary clamp 600.
The positions of cutting station 450 and stationary clamp 600 along
the length of machine 10 may be adjusted in order to facilitate
the creation of sutures with different lengths.
As illustrated in FIGS. 2-3 the combined tipping and cutting station
400 includes a pair of opposing tipping dies 402 404. The tipping
die 402 has both an open state (shown in FIG. 2) and a closed state
(shown in FIG. 3). When, as described above, the linear actuator
550 drives the moving clamp 500 from home position 510 to end position
512 the tipping die 402 in station 400 is in its open position.
After the moving clamp reaches its end position 512 and the stationary
clamp 600 has grasped or closed on the unfinished surgical suture
material 110 positioned within the stationary clamp 600 the tipping
die 402 moves from its open (or retracted) state to its closed (or
extended) state in order to facilitate the ultrasonic forming of
a predetermined length of surgical suture tip material. As described
in greater detail below in connection with FIGS. 2-5 while the
tipping die 402 is in its closed state, at least one of the tipping
dies 402 404 vibrates at an ultrasonic frequency in order to form
a length of surgical suture tip material. After the tipping die
402 has been in its closed state for a predetermined period of dwell
time (i.e., weld time plus hold time), tipping die 402 moves from
its closed to its open state, thereby yielding a length of tipped
surgical suture material positioned between dies 402 404. While
this length of tipped surgical suture material remains positioned
between dies 402 404 a further length of tipped surgical suture
material (previously tipped by station 400) which is positioned
within cutting station 450 is severed by station 450 thereby yielding
a tipped surgical suture with a cut end.
While the surgical suture material positioned at station 400 is
being tipped, the moving clamp 500 opens and releases the surgical
suture material within its grasp and, with the tipping die 402 still
in its closed state, the linear actuator 550 drives the moving clamp
500 from its end position 512 to its home position 510 where the
moving clamp closes on a next piece of unfinished surgical suture
material 110. Next, after the tipping of the surgical suture material
at station 400 is completed and the tipping die 402 is in its open
state, the suture material at station 450 is cut. Thereafter, the
stationary clamp 600 releases the surgical suture material within
its grasp (i.e., a finished surgical suture with a cut tip), the
linear actuator 550 drives the closed moving clamp back to its end
position 512 and the process described above is then preferably
repeated in order to manufacture further finished surgical sutures.
Since the tensioning assembly 200 exerts a tensioning force on the
surgical suture material 110 positioned within machine 10 it is
important for the moving clamp 500 to grasp or close on the surgical
suture material prior to the time that the stationary clamp 600
opens, in order to prevent the tensioning assembly 200 from pulling
the trailing end of the surgical suture material cut by station
450 in a reverse direction when the tipped surgical suture material
is severed by station 450.
The unfinished surgical suture material 110 used in machine 10
for manufacturing the finished sutures may consist of any thermoplastic
braided suture material such as, for example, a polyester braided
suture material, or a polyamide or polyolyfin suture material. In
addition, the unfinished surgical suture material 110 used in machine
10 may consist of silk or linen material, in which case, machine
10 may be used to ultrasonically fuse silk or linen tips. Alternatively,
the unfinished surgical suture material 110 used in machine 10 may
consist of nylon material, in which case, machine 10 may be used
to ultrasonically fuse nylon tips. In a preferred embodiment of
the present invention described more fully below, the unfinished
surgical suture material 110 used in machine 10 is a braided suture
material formed of a polyethylene terephthalate, such as that sold
by Ethicon, Inc. under the trademark Ethibond.RTM. Excel.RTM.. In
a preferred embodiment, a Simatic model TI435 controller manufactured
by Siemens is used to implement controller 800. An operator interface
is preferably coupled to the controller 800.
Operation of Tipping Dies
As mentioned above, after the moving clamp 500 has reached its
end position 512 the tipping dies 402 404 in the tipping station
400 operate to ultrasonically form a predetermined length of surgical
suture tip material from the unfinished surgical suture material
110 positioned within the station 400. During the operation of the
tipping dies 402 404 the unfinished surgical suture material 110
is suspended in an aligned and fixed positioned within station 400
by the stationary clamp 600 which is positioned on one side of station
400 and by the pulley 514 which is positioned on an opposing side
of station 400. In addition, during the operation of the tipping
dies 402 404 the unfinished surgical suture material 110 suspended
within station 400 is maintained at a preset tension by tensioning
system 200.
FIGS. 2 and 3 show two views of the tipping station 400. Each of
the views illustrates the position of the tipping dies 402 404
at a particular point during a suture tipping cycle. Referring now
specifically to FIG. 2 there is shown a side view of station 400
wherein the tipping die 402 is in its retracted or open position.
FIG. 2 shows the position of tipping die 402 when the moving clamp
500 first reaches its end position 512. After the moving clamp 500
has reached its end position 512 a cylinder 406 (controlled by
controller 800) drives the tipping die 402 from its retracted to
its extended position. In moving the tipping die 402 between its
retracted and extended positions, cylinder 406 drives tipping die
402 along the axis indicated by arrows 408. FIG. 3 shows the position
of the tipping die 402 after the cylinder 406 has moved tipping
die 402 to its extended position. As the tipping die 402 is moved
to its extended position, a cross-sectional portion of the suture
material 110 suspended within station 400 is contacted by face 402a
of tipping die 402 and face 404a of tipping die 404. In a preferred
embodiment of the present invention, the cylinder 406 causes tipping
die faces 402a and 404a to apply pressure to (or squeeze) the outer
surfaces of the suture material 110 positioned between dies 402
and 404. In this preferred embodiment, about 25 PSI of pressure
is applied to the outer surfaces of the suture material when die
faces 402a and 404a "close-on" or squeeze the suture material
positioned in station 400.
After faces 402a and 404a have been brought together and the tipping
dies 402 404 have "closed on" the unfinished surgical
suture material 110 as shown in FIG. 3 one or both of the tipping
dies 402 404 vibrate at an ultrasonic frequency for a predetermined
weld time in order to form a suture tip. In the preferred embodiment,
tipping die 402 remains fixed in position during a dwell time (i.e.,
a weld time followed by a hold time) when the tipping dies 402
404 have closed-on the unfinished surgical suture material 110
and an ultrasonic horn 412 which is connected to tipping die 404
vibrates tipping die 404 along the axis 410 at a frequency of 15
KHz to 70 KHz and an amplitude of 0.0001 to 0.010 inches for about
0.050 to 10.0 seconds in order to form the suture tip. In a still
further preferred embodiment, horn 412 vibrates tipping die 404
at a frequency of 20 KHz to 40 KHz at an amplitude of 0.004 inches
for 200 ms during the suture tipping step. During the dwell time
when the tipping dies 402 404 have closed-on the unfinished surgical
suture material 110 the vibrating of tipping die 404 against tipping
die 402 causes filaments within the interior or core 112 (shown
in FIG. 6) of the unfinished surgical suture material 110 (as well
as filaments on the exterior surface 114 of the suture material)
to fuse or weld together, thereby forming a length of surgical suture
tip material between dies 402 404. Thereafter, at the end of the
dwell time, the cylinder 406 opens the tipping die 402 by bringing
it back to its initial retracted position. In the preferred embodiment,
a transducer 414 which is coupled to horn 412 by a booster 416 is
used for vibrating horn 412. Booster 416 functions to control the
amplitude of the ultrasonic vibrations. A finished surgical suture
formed with an ultrasonically fused suture tip as described above
has been found to exhibit a tensile strength along the suture tip
that is about 75% to 84% of the tensile strength of the body portion
(i.e., the untipped portion) of the finished suture.
The tipping parameters used to form an ultrasonically fused tip
vary depending upon the diameter of the unfinished suture material
110 being supplied to machine 10. Set forth in Table I below are
the preferred tipping parameters used for ultrasonically forming
tips on different sizes of an unfinished braided suture material
formed of a polyethylene terephthalate, such as that sold by Ethicon,
Inc. under the trademark Ethibond.RTM. Excel.RTM.. Also set forth
in Table I below for each size suture is the preferred pressure
to be applied to the exterior surfaces of the suture material by
tipping dies 402 404 when the tipping dies first "close-on"
the unfinished suture material, the preferred frequency that tipping
die 404 should vibrate during the ultrasonic tipping process, and
the preferred dwell times during which the tipping dies 402 404
should remain closed on (and vibrate against) the unfinished suture
material 110 during the ultrasonic tipping process.
TABLE I ______________________________________ SIZE 0 2/0 3/0 4/0
5/0 ______________________________________ Tipping Die 80 25 25
15 5 Pressure (in PSI) Tipping Die 15-70 15-70 15-70 15-70 15-70
Vibration Frequency (in KHz) Tipping Die 0.900- 0.400- 0.100- 0.025-
0.025- Weld Time 10.0 5.0 5.0 2.0 2.0 (in seconds) Tipping Die 0.100-
0.100- 0.100- 0.100- 0.100- Hold Time 0.500 0.500 0.500 0.500 0.500
(in seconds) ______________________________________
In the preferred embodiment of the present invention, tipping dies
402 404 are made of steel, and are coated with a non-stick substance
such as TiN, Teflon.RTM. or Nedox.RTM., in order to facilitate the
release of the suture material from the tipping dies 402 404 when
such dies are opened. Although in the preferred embodiment described
above, the tipping dies 402 and 404 were a particular shape, it
will be understood by those skilled in the art that tipping dies
defining other shapes, such as those shown in FIGS. 7 and 8 may
also be used to ultrasonically form suture tips in accordance with
the present invention. Similarly, although the ultrasonically tipped
suture shown in FIG. 6 has a circular cross-section, it will be
understood by those skilled in the art that ultrasonically tipped
sutures having cross-sections of other shapes (e.g., polygonal)
may be formed in accordance with the present invention by varying
the shape and orientation of the tipping dies employed.
Suture Tensioning System
Referring now to FIG. 13 there is shown an isometric view of the
system 200 for tensioning a length of surgical suture material 110
in accordance with a preferred embodiment of the present invention.
System 200 includes a tensioning spool 202 having a width, a weight
and a circular perimeter 204 perpendicular to the width of the spool.
The tensioning spool 202 has a groove 206 in its perimeter 204 for
receiving the surgical suture material 110. Tensioning system 200
also includes a track 208 formed from a pair slots 208a, 208b extending
in parallel along the length of the track 208. Track 208 and slots
208a, 208b are preferably positioned along a purely vertical axis,
although, in alternate embodiments (not shown), track 208 and slots
208a, 208b may be aligned along an axis that includes both horizontal
and vertical components. The slots 208a, 208b function to receive
and guide the tensioning spool 202 along the length of track 208
during operation of system 200. The length of the track 208 is preferably
aligned perpendicularly to the width of the tensioning spool 202.
During operation of the system 200 the tensioning spool 202 is
suspended vertically within slots 208a, 208b by the surgical suture
material 110. While the tensioning spool 202 is suspended vertically
within slots 208a, 208b by the surgical suture material 110 the
weight of the tensioning spool 202 exerts a corresponding tensioning
force on the suture material 110 equal to the weight of spool 202.
In order to vary the tension exerted on the suture material 110
during operation of system 200 additional weights 210 may be added
or removed from a spool arm extending from the center of spool 202.
The tension exerted on the suture material 110 during operation
of system 200 preferably represents the minimum tension necessary
to prevent the suture material 110 from getting "bunched-up"
as it is pulled through machine 10 by moving clamp 500.
When the moving clamp 500 described above is in its grasping state
and moves from its home position 510 to its end position 512 suture
material 110 suspended in the slots 208a, 208b is drawn forwardly
through station 400 of machine 10. As the suture material is drawn
forwardly through the machine by the moving clamp 500 the tensioning
spool 202 is pulled upwardly within slots 208a, 208b. However, regardless
of the vertical position of the spool 202 within the slots 208a,
208b, the tension exerted on the suture material 110 by system 200
will be the constant and equal to the weight of spool 202. An optical
sensor 212 coupled to controller 800 is provided for determining
whether the pulling action of the moving clamp 500 has caused the
spool 202 to be drawn upwardly within the track 208 past the height
of the sensor 212. When optical sensor 212 detects that the tensioning
spool 202 has been pulled upwardly past the location of the sensor
212 controller 800 causes a motor (not shown) coupled to the supply
spool 100 to unwind unfinished surgical suture material 110 from
the supply spool 100. As further unfinished surgical suture material
110 is unwound from the supply spool 100 the tensioning spool 202
moves downwardly within the track 208. In the preferred embodiment,
controller 800 continues to unwind unfinished surgical suture material
110 from the supply spool 100 until the tensioning spool 202 falls
below the level of optical sensor 212.
An optical sensor 214 is provided at the bottom of track 208 for
determining whether there has been a break in the surgical suture
material 110 or a loss of tension in the suture material within
machine 10. Since, during normal operation, the tensioning spool
202 should not fall below the level of optical sensor 212 a break
in suture material 110 or a loss of suture tension within machine
10 will be signaled by sensor 214 if the sensor determines that
the tensioning spool 202 has fallen to the level of the sensor 214.
Knot Detection System
Referring now to FIGS. 14 and 15 there are shown two isometric
views of an optical detection system 300 for detecting knots in
surgical suture material 110 passing through system 300 in accordance
with a preferred embodiment of the present invention. Knot detector
system 300 includes an optical light source 302 for directing a
plane of light 304 at an optical light detector 306 when surgical
suture material 110 is positioned between the optical light source
302 and the optical light detector 306. The optical light source
302 is preferably formed of a plurality of optical fibers 302a having
their terminating ends aligned along the optical plane 304. Controller
800 is coupled to an output of the optical light detector 306 for
processing the signals output by detector 306 and determining whether
a knot exists in the suture material 110 positioned between the
light source 302 and light detector 306. More particularly, by comparing
a magnitude of a shadow 308 cast on the optical light detector 306
by the suture material 110 against a predetermined threshold, controller
800 determines whether or not a knot exists in the suture material
110 positioned between the light source 302 and light detector 306.
In a preferred embodiment, the predetermined threshold used in this
comparison corresponds to a magnitude of a shadow 308a cast on the
optical light detector 306 by an unknoted cross-section of suture
material 110. In a still further preferred embodiment, controller
800 will determine that a knot exists in the suture material 110
passing through system 300 only if the magnitude of the shadow cast
on light detector 306 by suture material 110 exceeds by at least
30% the magnitude of a shadow 308a cast on the optical light detector
306 by an unknoted cross-section of suture material 110.
Extended Length Suture Mode
Although, in the process described above, machine 10 was used to
manufacture a finished surgical suture having a length that was
less than length of the linear actuator 550 machine 10 may also
be used in an extended length suture mode, described below, in order
to make finished surgical sutures which are longer than linear actuator
550. During operation of the machine 10 in the extended length suture
mode, the moving clamp 500 initially grasps or closes on the unfinished
surgical suture material 110 at the home position 510. Next, while
the moving clamp 500 remains in its grasping or closed state, the
linear actuator 550 drives the moving clamp 500 from its home position
510 to the end position 512. As the linear actuator 550 drives moving
clamp 500 from its home position 510 to its position 512 the moving
clamp 500 pulls a length of the unfinished surgical suture material
110 through the tipping station 400 cutting station 450 and through
the stationary clamp 600. After the moving clamp reaches its end
position 512 the stationary clamp 600 grasps or closes on the unfinished
surgical suture material 110 positioned within the stationary clamp
600. The moving clamp 500 then releases the unfinished surgical
suture material 110 in its grasp. Next, while the moving clamp is
in its open or non-grasping state, the linear actuator 550 drives
the moving clamp 500 from its end position 512 to its home position
510 where the moving clamp 500 again grasps or closes on the unfinished
surgical suture material 110 at the home position 510. After the
moving clamp 500 grasps the unfinished surgical suture material
110 at the home position 510 for the second time, the stationary
clamp 600 opens. Thereafter, while the moving clamp 500 remains
in its grasping or closed state and the stationary clamp 600 remains
in its open state, the linear actuator 550 again drives the moving
clamp 500 from its home position 510 to the end position 512. After
the moving clamp 500 reaches its end position 512 for the second
time, the stationary clamp 600 again grasps or closes on the unfinished
surgical suture material 110 positioned within the stationary clamp
600.
After the unfinished surgical suture material 110 has been "pulled
twice" by the moving clamp 500 as described in the paragraph
above, the dies 402 404 in the tipping station 400 function as
described above to ultrasonically form a length of surgical suture
tip material positioned within the station 400. Following the cutting
of this suture tip material at station 450 the stationary clamp
600 releases the surgical suture material within its grasp. As the
stationary clamp opens and releases the previously grasped surgical
suture material, a finished surgical suture having an ultrasonically
formed and cut tip results. Since the moving clamp 500 pulled the
suture material 110 two times consecutively before the tipping station
400 formed the suture tip, the resulting finished surgical suture
produced by the extended length suture mode may have a length which
is greater than the length of the linear actuator 550.
Continuous Process Using Circular Tipping Dies
Referring now to FIGS. 17 and 18 there are shown side and cross-sectional
views of an alternative suture tipping station 400a formed of opposing
circular tipping dies 440 450 for continuously tipping unfinished
surgical suture material 110a, in accordance with an alternative
preferred embodiment of the present invention. Tipping die 440 contains
a notch 403 around a portion of its perimeter, and tipping die 450
contains a corresponding groove 405 positioned about its perimeter.
In the preferred embodiment of station 400a, notch 403 is sized
such that pressure is applied to the exterior surface of suture
material 110a when suture material 110a is between notch 403 and
the lower end of groove 405. Tipping dies 440 450 are coupled to
mechanical actuators (not shown) which continually rotate the dies
440 450 in the direction of the arrows shown in FIG. 17. During
rotation of the tipping dies 440 450 an ultrasonic horn (also
not shown) vibrates tipping die 440 against tipping die 450 at a
frequency of 15 KHz to 70 KHz (and preferably 20 KHz to 40 KHz)
and an amplitude of 0.0001 to 0.010 inches in order to continuously
form suture tip material. Station 400a may be substituted for station
400 in FIG. 1 in order to configure machine 10 to continuously
produce surgical sutures with ultrasonically formed tips, in accordance
with the present invention.
Referring now to FIG. 19 there is shown a side view of a suture
tipping and cutting station 400b formed of opposing circular tipping
and cutting dies 440a, 450 for continuously tipping and cutting
unfinished surgical suture material 110 in accordance with a further
alternative preferred embodiment of the present invention. Die 440a
is substantially the same as die 440 except that die 440a includes
a cutting point 403b for cutting a suture tip end portion during
the rotation of die 440a against 450. Station 400b functions substantially
the same as station 400a, except that station 400b may be used to
both form and cut suture tips in a continuous manner. Since the
cutting performed by station 400b is accomplished using a cutting
point 403b which vibrates at an ultrasonic frequency, a suture tip
is simultaneously both cut and sealed by station 400b. In addition,
the ultrasonic cutting action of point 403b yields a cut suture
tip with a lead angle which facilitates the insertion of the cut
suture tip into a drilled needle. Although in the preferred embodiment
of station 400b, dies 440a and 450 function to both tip and cut
surgical suture material 110 it will be understood by those skilled
in the art that two separate pairs of circular dies may be employed
in series to respectively perform the tipping and cutting operations.
Furthermore, it is to be understood that although the present invention
has been described with reference to a preferred embodiment, various
modifications, known to those skilled in the art, may be made to
the structures and process steps presented herein without departing
from the invention as recited in the several claims appended hereto.
|