Needle and suture automatic pull-test system

An automatic pull-testing apparatus for testing the strength of an armed surgical needle comprises a supporting blade for supporting a suture receiving end of the armed needle and having at least one suture receiving guide therein. A first gripping device is provided for releasably retaining the armed needle in an oriented position, and for positioning the armed needle at the supporting blade to enable the suture strand depending therefrom to be threaded at the suture receiving guide. A second suture gripping device grips the suture at a position below the suture receiving guide of the supporting blade. A slide block counterweighted to a predetermined weight is connected to the second suture gripping device for applying a controlled positive downward force upon the suture strand. When the first gripping device releases its grip upon the armed needle and the second gripping device and the slide block is released, a positive downward force is applied to the suture strand to perform a minimum pull-test of the armed needle. A destructive pull test is also performed by a device that generates a positive force against the slide block that is sufficient to dislodge the suture from the needle.

FIELD OF THE INVENTION 
The present invention relates generally to machines for automatically 
packaging surgical needle-suture combinations, i.e., armed-needles, and 
more specifically, to an apparatus and method for automatically testing 
the strength of an armed surgical needle to ensure that pull-test 
requirements are met prior to packaging thereof. 
DESCRIPTION OF THE PRIOR ART 
Currently, most armed surgical needles, i.e., needles having sutures 
attached to one end thereof, are manufactured utilizing manual and 
semi-automated procedures such as those described in U.S. Pat. Nos. 
3,611,551, 3,980,177, and 4,922,904 which generally disclose devices that 
feed a length of suture material to the crimping end of a surgical needle 
(U.S. Pat. Nos. 3,980,177 and 4,922,904), and devices that swage the 
suture tip to the surgical needle. 
U.S. Pat. No. 3,980,177 in particular discusses the requirement of the 
surgeon or medical personnel using the armed needle to be able to detach 
the needle from the suture after suturing to avoid the necessity of 
cutting the suture with scissors. The patent itself is drawn to a 
needle-suture combination that is characterized as having a straight 
pull-out value between 3 ounces and 26 ounces depending upon the size of 
the suture. This patent, however, does not disclose a means for testing 
the armed-needle to determine its pull-out value, i.e., the means for 
providing the force necessary to detach the needle from the suture. 
U.S. Pat. No. 4,922,904 discloses a means for confirming whether a length 
of suture has been firmly connected to the surgical needle or not by 
applying tension to the suture after swaging thereof and prior to cutting 
the suture. No means or method is provided for determining the amount of 
force that is required to separate the needle from the suture. 
However, it is desirable to provide an automatic pull-test system that is 
designed to determine whether a needle-suture combination meets the 
recommended minimum pull-test requirements as set forth by the medical 
profession. 
Furthermore, it would be desirable to provide an automatic pull-test system 
that automatically determines whether the needle-suture combination meets 
the minimum pull-test requirements, and furthermore, one that is 
implemented in an automatic needle threading and swaging system that 
automatically cuts a predetermined length of suture material and 
automatically swages the suture to the needle. 
It is also desirable to provide an automatic pull-test system that can 
perform minimum pull-testing and destructive pull-testing of the armed 
needle prior to packaging thereof. 
Moreover, it would be desirable to provide an automatic pull-test system 
that is operated under the control of a control system computer that can 
perform minimum pull-testing of the armed needle without manual 
intervention and with a minimum amount of time expenditure. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the instant invention to provide an 
automatic pull-test system that can automatically perform minimum 
pull-testing of the armed needle in a cost-effective manner and without 
manual intervention. 
Furthermore, it is an object of the present invention to provide an 
automatic pull-test system, wherein the armed-needle is automatically 
indexed to an automatic pull-test station after the suture has been cut 
and swaged to the surgical needle, and prior to packaging thereof. 
It is another object of the instant invention to provide a cost-effective 
automatic pull-test system that can perform a destructive pull-test of an 
armed surgical needle at a predetermined intervals, and moreover, that can 
retain the destructive pull-test values for statistical analysis thereof 
and statistical process control. 
Still another object of the instant invention is to provide an automatic 
pull-test system that can perform a destructive pull-test of an armed 
needle and retain the maximum pull-test values thereof, and moreover, one 
that can provide automatic adjustment of the upstream swaging dies used to 
produce the armed needle in accordance with statistical process control 
values. 
These and other objects of the present invention are attained with an 
automatic pull-test apparatus and system for automatically testing the 
strength of an armed needle having a suture attached thereto. The 
apparatus comprises a blade means for supporting a suture receiving end of 
the armed needle when a positive downward force is applied to the suture 
strand, and having at least one suture receiving guide therein. A first 
multi-axis gripping means is provided for releasably retaining the armed 
needle in an oriented position and for positioning the armed needle above 
the blade means to enable the suture strand depending therefrom to be 
threaded at the suture receiving guide therein. A second suture gripping 
means grips the suture strand at a position below the suture receiving 
guide of the blade means and is maintained at that position prior to 
applying the downward force. A slide block of predetermined weight is 
connected to the second suture gripping means for applying a positive 
downward force of a predetermined value upon the suture strand along the 
vertical axis defined by the suture strand. When the first gripping means 
releases its grip of the needle and the second gripping means engages the 
suture strand, a positive downward force is applied by the slide block for 
performing minimum or destructive pull-testing of the armed needle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The process of arming surgical needles, i.e., drawing of the suture 
material, cutting predetermined lengths thereof, threading and swaging the 
cut suture material to the surgical needle, is described in further detail 
in copending patent application Ser. No. 08/181,595 (attorney docket No. 
8924) and application Ser. No. 08/181,599 (attorney docket No. 8937) 
assigned to the same assignee of the present invention and incorporated by 
reference herein. 
The automatic pull-test assembly 10 for accomplishing automatic 
pull-testing of an armed surgical needle is shown generally in FIGS. 1 
through 2(c). The automatic pull-test assembly 10 generally comprises a 
load cell mounting assembly 30 for mounting a load cell 35 which functions 
to receive the armed needle 20 from the multi-axis gripper 55 which is 
indexed thereto as shown in FIG. 1. A needle release assembly 15 is 
provided for relaxing the armed needle from the grip of the multi-axis 
gripper 55. Pull-test fence assembly 40 is provided to prevent the armed 
needle 20 from tipping over or becoming misaligned when the multi-axis 
gripper relaxes its hold on the armed needle. Suture gripping assembly 70 
containing retractable gripper arms 25a,b for gripping the suture 19 
during the pull-tests, and which are connected to the weighted slide block 
assembly 72 for performing the pull-test is provided as shown in FIG. 1. A 
detailed description of each of these assemblies and their interaction 
will be explained in detail hereinbelow. 
As shown in FIGS. 1 and 2(a), an armed surgical needle 20 is retained by a 
multi-axis gripper 55 and is indexed to the automatic pull test assembly 
10 by the rotary swage dial 12 partially illustrated in FIG. 2(a). The 
multi-axis gripper 55 is movable between an extended and retracted 
position relative to the pull-test station and details of the indexing 
operation of the rotary swage dial 12 and the retractable nature of the 
multi-axis gripper can be found in copending U.S. patent application Ser. 
No. 08/181,598 (attorney docket No. 8922) assigned to the present assignee 
of the instant invention and incorporated by reference herein. 
To position the armed needle 20 in the load cell 35, the multi-axis gripper 
is extended from the swage dial 12 so that the barrel portion 21 of needle 
20 is positioned above a corresponding receiving blade of the load cell 35 
as shown in FIG. 1. FIG. 3 illustrates a top view of the load cell 
mounting assembly 30 with load cell 35 mounted thereon. In the preferred 
embodiment, load cell 35 includes a flat disc (FIG. 1) comprising four 
thin needle supporting blades 36a,b,c,d for supporting the barrel portion 
21 of various size surgical needles with the suture material 19 depending 
therefrom. For instance, load cell needle supporting blade 36a labelled 
"1/0" accommodates larger sutures having a diameter of approximately 
0.017.+-.0.001 inches; load cell needle receiving blade 36b labelled "2/0" 
accommodates sutures having a diameter of approximately 0.014.+-.0.001 
inches; load cell needle receiving blade 36c labelled "3/0" accommodates 
sutures having a diameter of approximately 0.011.+-.0.001 inches; and load 
cell needle receiving blade 36d labelled "4/0" accommodates a smaller 
suture with a diameter of approximately 0.009.+-.0.001 inches in the 
preferred embodiment. Depending upon the batch of surgical needles 
currently being pull tested, the appropriate receiving blade 36a,b,c,d 
will be positioned to receive the needle from the multi-axis gripper. Knob 
39 located centrally on top of the load cell 35 may be manually operated 
to rotate the load cell blades and position the correct sized needle 
receiving blade prior to carrying out automatic pull-testing. 
Additionally, the load cell 35 may be laterally positioned by moving slide 
handle 38 and consequently load cell carriage 37 towards or away from the 
suture needle indicated by the arrow in FIG. 3. 
The multi-axis gripper 55 is initially positioned so that the barrel 
portion 21 of armed needle 20 is supported by the appropriate needle 
supporting blade 36 (e.g. blade 36b). FIG. 4 is a front cross sectional 
view illustrating the barrel portion 21 of needle 20 resting upon the 
needle supporting blade 36b with the suture strand 19 threaded between the 
suture receiving opening 34. 
Non-destructive pull testing of the armed surgical needle 20 is 
accomplished as follows: 
After positioning the multi-axis gripper as heretofore described, gripper 
arms 25a,b of suture gripping assembly 70 are extended from a retracted 
position to grip the suture strand 19 slightly below the needle supporting 
blade 36 of load cell 35 as shown in FIG. 1. A gripper actuator 72a is 
provided for opening and closing gripper arms 25a,b, as shown in FIG. 1, 
and is controlled by a control system program resident in control system 
computer 75 as explained in further detail in copending patent application 
Ser. No. 08/181,607 (attorney docket No. 8927) assigned to the same 
assignee of the present invention. FIGS. 1 and 2(a) illustrate the slide 
assembly including slide block mount 72 that is composed of slide rods 
72b,c that are connected to a lower slide block 72d. Slide block 72d 
includes a slide finger 72e upon which air cylinder piston rods 74a and 
79a, of respective air cylinders 74, 79, apply respective upward and 
downward forces depending upon the type of pull-test that is to be 
performed. As shown in FIG. 2(a), piston rod 74a is shown in an extended 
position providing an upward force that supports slide finger 72e and 
consequently maintains slide block 72d of slide assembly 72 at a fixed 
vertical position. 
Slide block 72d is counterweighted to a net downward weight of 2 to 5 
ounces by appropriately sized counterweight 76 that acts through cable 73, 
around pulley 77, and through attachment point 72h. This counterweight 76 
acts to pull upward on slide block 72d at the attachment point 72h. 
To accomplish the non-destructive pull test, piston rod 74a of air cylinder 
74, mounted on the mechanism frame 71 and controlled by system computer 
75, is retracted from its extended position (FIG. 2(a)) supporting the 
slide finger 72e as shown in dashed line in FIG. 2(b), by reversing its 
air supply (not shown), to the position shown in the figure. The piston 
rod 74a is retracted to remove the upward force on slide finger 72e, as 
shown in the FIG. 2(b), to thereby impose the counterbalanced net weight 
of 2 to 5 ounces of slide block 72d on the swage attachment means of 
suture 19 in needle 20, in the direction of arrow "A". Accuracy of this 
system is enhanced because slide block 72d, suspended on slide rods 72b,c, 
are mounted in low friction ball bushings, 72f and 72g, that are pressed 
into slide mount 71, thereby imposing minimal mechanical drag on the 
system. 
Note in FIG. 1, that the slide block mount 72 is positioned parallel to the 
axis of the suture 19 depending from the needle 20, and is located a 
distance away from the suture 19 corresponding to the length of the 
gripper arms 25a,b. 
Simultaneous with or momentarily before the slide assembly 72 is released, 
the needle release assembly 15 is actuated to enable multi-axis gripper 55 
to disengage its grip on the armed needle 20. Releasing the armed needle 
from the grip of the gripper 55 is necessary to ensure that it is firmly 
positioned on the load cell needle supporting blade 36. Moreover, to 
provide an accurate pull-test, the needle must be released so that there 
is no existing upward force that would cause false results. 
As shown in FIG. 1, needle release assembly 15 comprises needle release 
solenoid 24 that is actuated to extend pusher 26 into pivotal lever arm 
27. Pivotal lever arm 27 pivots about pin 28 to depress plunger 49 of the 
multi-axis gripper 55 at one end 29 thereof. As shown in FIG. 2, 
depressing plunger 49 enables pin 42 to retract within pin guide 47 to 
release the armed needle 20 engaged thereby. Further details of the 
operation of the multi-axis gripper 55 can be found in the above-mentioned 
copending patent application Ser. No. 08/181,599 (attorney docket 8937). 
To prevent the armed needle 20 from becoming misaligned or from tipping 
over after the multi-axis gripper 55 releases its grip on the needle, a 
needle fence assembly 40 is provided. As shown in FIG. 2(a), the needle 
fence assembly 40 includes vertical fence plate 43 which can be adjusted 
to lie flush against the gripper 55 to retain the armed needle in an 
upright position. Adjusting the lateral positioning of the vertical fence 
plate 43 is accomplished by moving slide handle 43a for an appropriate 
distance as shown in FIG. 1. In the preferred embodiment, the 
configuration of the face of the vertical needle fence plate 42 (not 
shown) may be changed to accommodate the configurations of different size 
needles: 
The controlled release of the minimum pull-test is of short duration, 
preferably ranging in milliseconds. If the test is successful, i.e., the 
suture meets the minimum pull-test requirements, the needle is re-gripped 
by the multi-axis gripper 55 by deactuating the needle release solenoid 24 
(FIG. 1) which releases the force on plunger 49. The suture grippers 25a,b 
are then retracted to their open position to release their grip on the 
suture 19 as controlled by the control system. Subsequently, the 
multi-axis gripper 55 is retracted and the rotary swage dial is rotated to 
convey the armed needle downstream for further processing. 
If the suture fails the minimum pull-test, i.e., if the suture 19 is 
dislodged from the surgical needle 20 as a result of the controlled 
release, the control system computer 75 is flagged so that the disarmed 
needle 20 will be ejected at the pull-test station. The dislodged suture 
strand 19 will be drawn into a vacuum assembly (not shown) and the needle 
20 will be ejected by a needle stripper assembly 80 shown generally in 
FIG. 2(a) and in detail in FIG. 5. As shown in FIG. 5, needle stripper 
solenoid 82 will be actuated by a control signal output from the control 
system computer 75 to extend needle stripper blade 85 mounted on a slide 
block 83. The needle stripper blade 85 is shown in FIG. 1 located next to 
the needle 20. Thus, when the needle is in its relaxed state on the 
multi-axis gripper 55 and the minimum pull-test fails, the needle stripper 
blade 85 is extended to remove the needle from the gripper. The needle 
will fall and be collected by appropriate collection means (not shown) 
located at the pull-test station. 
To prepare for the next armed needle to be pull-tested, the slide assembly 
72 and retracted gripper arms 25a,b are pushed back up the slide mount 71 
to their unloaded position by an appropriate upward force supplied by the 
air cylinder 74 and piston rod 74a as controlled by the control system 
computer 75. At this time, another flag may be sent for storage to the 
control system computer that indicates that the pull-test performed on the 
particular needle 20 was successful and that the armed needle may be 
conveyed downstream for packaging thereof. 
In the preferred embodiment of the minimum and destructive pull-test 
systems shown in FIGS. 1-3, the load cell 35 and the needle support blades 
36a,b,c,d thereof comprise a piezoelectric transducer that measures the 
force applied by the suture gripping assembly to the needle-suture 
assembly 19. The transducer load cell 35 may be interfaced with the 
control system computer 75 by conventional means as shown in FIGS. 1 and 
3, and, in the preferred embodiment, is a 1000 gram transducer 
manufactured by Techniques Co. (Model No. GS-1K). The forces applied to 
the suture 19 and measured by the load cell transducer 35 during the 
destructive pull-testing may be stored for statistical purposes or for 
real-time monitoring during a swage die setup routine that may take place 
when a new batch of surgical needles are to be swaged. For instance, if 
the destructive pull-tests fail and the forces measured by the transducer 
are determined to be at the low end of a predetermined range, then the 
control system computer 75 will acknowledge this and send appropriate 
signals to the upstream swaging assembly (not shown) causing a fixed 
swaging die to be advanced an incremental amount toward the moveable swage 
die, resulting in subsequent swages being stronger. Likewise, if the 
destructive pull-test passes, i.e., the forces measured by the transducer 
are determined to be above the minimum and below an upper limit, then no 
die adjustment need be made. 
As previously mentioned, the automatic pull-test assembly 10 is used to 
perform a minimum pull-test upon every armed surgical needle indexed 
thereto prior to automatic packaging thereof. A destructive pull-testing 
of the armed surgical needle is performed at every nth needle indexed 
thereto. The purpose of performing a destructive pull-test is to set the 
swage dies located at the upstream swaging station for correct maximum 
swage pull-out value. This is by necessity a destructive test, and the 
test frequency, which is programmable, is set high enough to maintain 
control of the operation, but low enough to avoid excessive product waste. 
In the preferred embodiment, this frequency is set at every 50th needle, 
but could be every 75th or 100th needle. 
Another purpose of the destructive pull test is to aid in installing a new 
swage die set during a changeover procedure, which is a procedure that is 
used to prepare the needle sorting and swaging apparatuses (swage dies) 
for processing a new batch of needles when they are of a different size 
from a previously processed batch. Contrary to the non-destructive 
pull-test described above, the pull-test apparatus is programmed for 100% 
destructive test of a swaged needle, while the swaging assembly is 
operating and feeding the armed needles to the pull-test station. The die 
adjustment system at the upstream swaging assembly will receive a signal 
from the transducer load cell 35, at each machine cycle, and quickly 
perform a correct adjustment of the swage dies. 
Destructive test pull-out values are recorded in the system computer 75 and 
are used to compute statistical process control information which is fed 
back to the machine operator through display screens. 
Destructive pull testing of the armed surgical needle 20 is accomplished 
similarly as described herein above with respect to the minimum pull test. 
However, the fundamental difference is that a fixed mechanical stroke that 
is great enough to pull the suture out of the needle replaces the minimum 
2 to 5 ounce force of the minimum pull test. 
As shown in FIG. 2(c), piston rod 79a of second air cylinder 79 located 
opposite air cylinder 74, is programmed to provide a fixed stroke against 
slide finger 72e from a non-actuating position shown in FIG. 2(a) to the 
position shown in FIG. 2(c). This results in the vertical displacement of 
slide finger 72e from a position shown by the dashed line to a position 
shown by the solid line. This further results in a downward force upon 
slide block 72d, which, through slide rods 72b and 72c, moves slide 
assembly 72, including grippers 25a,b and suture 19, in the direction of 
the arrow "B" as shown in FIG. 2(c). Air pressure to cylinder 79 is set 
high enough to always pull suture 19 out of needle 20. This stroke is 
limited by the underside of top portion 72j of slide assembly 72 striking 
the top of stationary block 71. 
The force necessary to accomplish the destructive pull-test is measured by 
the piezoelectric load cell transducer 35 as discussed above. If it is 
determined by the process control algorithm (not shown) that the 
destructive pull-test forces as measured by the transducer load cell are 
lower than a predetermined range of pull-test values, the control system 
computer 75 will send out appropriate control signals to increase the 
swaging die stroke applied when swaging the suture to the needle at the 
upstream swaging station. If it is determined that the destructive 
pull-test forces as measured by the transducer load cell are higher than 
the predetermined range, the control system computer 75 will send out 
appropriate control signals to the upstream swaging assembly to move a 
fixed swage die a small incremental distance away from the suture, thereby 
decreasing the swaging pressures applied when swaging the suture to the 
needle. 
Since the destructive pull-test necessarily results in the suture 19 
becoming dislodged from the needle 20, the needle 20 is again removed from 
the grip of the multi-axis gripper 55 by the needle stripper blade 85 as 
described above. Subsequently, the gripper arms 25a,b are retracted to 
their open positions and air cylinder 74 provides the upward force to 
restore the gripping assembly 70 and slide block assembly 72 back to their 
normal position in preparation for the next pull-test. 
While the invention has been particularly shown and described with respect 
to the preferred embodiments thereof, it will be understood by those 
skilled in the art that the foregoing and other changes in form and 
details may be made therein without departing from the spirit and scope of 
the invention, which should be limited only by the scope of the appended 
claims.