Surgical needle abstract
An apparatus is provided for accurately forming suture cut-off
feature in a surgical needle of the socketed type.
Surgical needle claims
What is claimed is:
1. An apparatus for forming a suture cutting edge at the entrance
of a suture -receiving socket formed in the blunt end of a surgical
needle which comprises:
(a) tool means for forming the suture cutting edge;
(b) surgical needle receiving and holding means which, in a locked
position, accurately maintains the position of the socketed end
of the needle relative to the tool means during the suture cutting
edge forming operation, the surgical needle receiving and holding
means comprising a conical shaped collet possessing an axially extending,
centrally disposed needle-receiving bore for its full length and
open at each end thereof, the collet possessing a plurality of slots
extending from its front to its rear face and capable of undergoing
compression upon application of a compressive force to firmly lock
the blunt end of the needle within the bore;
(c) means for locking the socketed end of the needle within the
surgical needle receiving and holding means; and,
(d) means for advancing the tool means relative to the socketed
end of the needle by a predetermined distance
2. The apparatus of claim 1 wherein tool means (a) includes a fluted
drill bit.
3. The apparatus of claim 1 further comprising a collet holder
(e) possessing a conical opening for receiving the collet in surface
contacting engagement therewith, the collet holder permitting limited
forward movement of the collet therein such that application of
a force to the collet which drives the collet forward within the
collet holder imparts a compressive force to the collet locking
the needle within the bore thereof.
4. The apparatus of claim 1 wherein means (d) for advancing the
drilling means relative to the blunt end of the needle includes
a linear bearing supporting said drilling means.
5. An apparatus for forming a suture cutting edge at the entrance
of a suture-receiving socket formed in the blunt end of a surgical
needle which comprises:
(a) tool means for forming the suture cutting edge;
(b) surgical needle receiving and holding means which, in a locked
position, accurately maintains the position of the socketed end
of the needle relative to the tool means during the suture cutting
edge forming operation, the surgical needle receiving and holding
means comprising a conical shaped collet possessing an axially extending,
centrally disposed needle-receiving bore for its full length and
open at each end thereof, the collet possessing a plurality of slots
extending from its front to its rear face and capable of undergoing
compression upon application of a compressive force to firmly lock
the blind end of the needle within the bore;
(c) a collet holder possessing a conical opening for receiving
the collet of surgical needle receiving and holding means (b) in
surface contacting engagement therewith, the collet holder permitting
limited forward movement of the collet therein such that application
of a force to the collet which drives the collet forward within
the collet holder imparts a compressive force to the collet locking
the needle within the bore thereof;
(d) means for locking the socketed end of the needle within the
collet of surgical needle receiving and holding means (b), said
locking means comprising a locking ram possessing a downwardly sloping
front surface which, in the locking position of the ram, makes mating
engagement with an upwardly sloping surface defined upon the rear
face of the collet forcing the collet forward with the collet holder;
and,
(e) means for advancing tool means (a) relative to the socketed
end of the needle by a predetermined distance.
6. The apparatus of claim 5 wherein tool means (a) includes a fluted
drill bit.
7. An apparatus for forming a suture cutting edge at the entrance
of a suture-receiving socket formed in the blunt end of a surgical
needle which comprises:
(a) drilling means for forming the suture cutting edge, the drilling
means including a fluted drill bit driven by a high speed motor;
(b) a conical shaped collet for receiving, and in its locked position,
for firmly holding, the socketed end of a needle received therein,
said collet possessing an axially extending, centrally disposed
needle-receiving bore for its full length and open at each end thereof,
the collet possessing a plurality of slots extending from its front
to its rear face and capable of undergoing compression upon application
of a transversally directed compressive force to firmly lock the
blunt end of the needle within the bore;
(c) a collet holder possessing a conical opening for receiving
collet (b) in surface contacting engagement therewith, the collet
holder permitting limited axial forward movement of the collet therein
such that application of an axially directed force to the collet
which drives the collet forward within the collet holder imparts
a transversally directed compressive force to the collet locking
the needle within the bore thereof;
(d) a locking ram possessing a downwardly sloping front surface
which, in the locking position of the ram, makes mating engagement
with an upwardly sloping surface defined upon the rear face of col].et
(b) forcing the collet forward within collet holder (c) to thereby
impart a transversally directed compressive force to the collet
and firmly lock the needle present within the bore thereof into
position; and,
(e) a linear bearing supporting drilling means (a) and permitting
the advance of the drilling means toward the blunt end of the needle
by a predetermined distance.
8. The apparatus of claim 2 wherein the sloping surfaces of the
fluted drill bit define an inclusive angle x possessing a value
of from about 90.degree. to about 110.degree..
9. The apparatus of claim 7 wherein the sloping surfaces of the
fluted drill bit define an inclusive angle x possessing a value
of from about 90.degree. to about 110.degree..
10. The apparatus of claim 6 wherein the sloping surfaces of the
fluted drill bit define an inclusive angle x possessing a value
of from about 90.degree. to about 110.degree..
11. The apparatus of claim 5 wherein means (e) for advancing the
drilling means relative to the blunt end of the needle includes
a linear bearing supporting said drilling means.
Surgical needle description
CROSS REFERENCE TO RELATED APPLICATION
This application relates by subject matter to commonly assigned,
concurrently filed U.S. patent application Ser. No. 317948 filed
Mar. 2 1989 the contents of which are incorporated by reference
herein.
BACKGROUND OF THE INVENTION
This invention relates to apparatus for forming a suture cut-off
feature as an integral part of a suture-receiving socket previously
or concurrently formed within the blunt end of the surgical needle
component of a combined surgical needle-suture device
The prior art describes a variety of arrangements for securing
a suture within an axial socket, or recess, drilled into the blunt
end of a surgical needle and for providing release, or separation,
of the needle from the suture upon completion of suturing. Illustrative
of such suture-surgical needle combinations are those described
in U.S. Pat. Nos. 1757129; 3799169; 3910282; 3926194; 3943933;
3949756; 4054144; and, 4072041. Specific techniques provided
in these prior disclosures for achieving separation of the needle
from the suture include peeling the suture out of a channel formed
in the rear of the needle as shown in U.S. Pat. No. 3799169 and
tugging sharply at the needle within some predetermined range of
"pull-out" force to effect separation of the needle and
suture at the site of a weakened suture segment as shown in U.S.
Pat. Nos. 3926194; 3943933; 3949756; 4054144; and, 4072041.
U.S. Pat. No. 2910983 describes a suture surgical needle combination
in which the suture is held securely within a crimped socket possessing
an outer sharp circumferential edge. The sole disclosed function
of the sharp edge is to provide a flared entrance to the socket
thus preventing damage to the suture. There is no suggestion in
U.S. Pat. No. 2910983 of providing a sharp edge for the purpose
of achieving suture cut-off.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an apparatus for forming
a suture cut-off feature integrally associated with a suture-receiving
socket formed in the blunt end of a surgical needle intended to
receive, and retain, the tip of a suture therein.
It is a particular object of the invention to provide an apparatus
for forming a circumferential cutting edge at the entrance to the
suture-receiving socket which is capable of severing the suture
retained within the socket when separation of the needle from the
suture is desired.
It is another particular object of the invention to provide a collect
for receiving and firmly gripping the socketed end of a surgical
needle and accurately maintaining the position of the socketed end
of the needle relative to a tool during suture cutting edge forming
operation.
In keeping with these and other objects of the invention, there
is provided an apparatus for forming a suture cutting edge at the
entrance of a suture-receiving socket of a surgical needle which
comprises:
(a) tool means for forming the suture cutting edge;
(b) surgical needle receiving and holding means which, in a locked
position, accurately maintains the position of the socketed end
of the needle relative to the tool means during the suture cutting
edge forming operation;
(c) means for locking the socketed end of the needle within the
surgical needle receiving and holding means; and,
(d) means for advancing the tool means relative to the socketed
end of the needle by a predetermined distance.
In operation, a surgical needle is inserted socketed end-forward
into the needle receiving holding means of the foregoing apparatus.
Activation of the needle locking means provides precise alignment
of the socketed end of the needle with the cutting edge forming
tool so that with axial movement of the latter relative to the former
through a predetermined distance, a circumferential cutting edge
is formed which is integral with the entrance to the suture-receiving
socket.
The demands of precision, accuracy and dependability which are
imposed upon the apparatus herein in forming a suture cut-off feature
in a surgical needle of the socketed type are fairly prodigious
as can be readily appreciated from the Table, infra, setting forth
typical needle dimensions. In meeting these demands with a high
degree of reliability, the apparatus of the present invention represents
a significant development in the art of surgical needle manufacture.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A and 1B are enlarged cross sectional views of the axial
suture-receiving socket end of a preferred type of surgical needle
component of a surgical needle-suture combination manufactured by
the apparatus of this invention showing the side profile of the
socketed end of the needle before (FIG. 1A) and after (FIG. 1B)
attachment of the tip of the suture to the needle;
FIG. 2A is a perspective view of an axially movable cutting edge
forming tool for use in the apparatus of this invention;
FIG. 2B is an exploded perspective view of the principal elements
of the cutting edge forming apparatus of the invention;
FIG. 2C is an exploded side elevational view of the locking ram,
collet and collet holder elements of the apparatus of FIG. 2B; and,
FIG. 2D is a perspective view of the assembled apparatus of FIG.
2B.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The apparatus of the present invention and its operation will be
specifically described in connection with the manufacture of a preferred
type of surgical needle, i.e., the socketed needle possessing a
suture cut-off feature which is described in aforementioned commonly
assigned, concurrently filed U.S. patent application Ser. No. 317948
filed Mar. 2 1989 and in FIGS. 1A and 1B herein.
As shown in FIG. 1A, the rear portion of surgical needle 10 possesses
a sloping surface 11 defining the entrance to a concentrically positioned
socket 12. Sloping surface 11 terminates in a circumferential cutting
edge 13 which possesses an inclusive angle x formed at the junction
of opposed sloped surfaces. The cutting edge can be smooth as shown
or it can be notched or serrated to enhance its cutting action.
In FIG. 1B, tip 14 of suture 15 is shown occupying socket 12 of
needle 10 and is held tightly within the socket by a crimping of
needle section 16 about the tip of the suture, e.g., as described
in U.S. Pat. No. 3736646. Crimping has no appreciable affect upon
the value of inclusive angle X. To effect separation of the needle
from the suture, the suture is oriented relative to the needle such
that the suture is made to bear against any location along the circumferential
cutting edge of the needle socket entrance and, while the suture
is held in tension against the cutting edge, an arc-like, or sweeping,
movement of the suture against the cutting edge is employed to effect
separation of the needle from the suture at their junction.
Aforesaid angle x which defines the slope of the socket entrance
is critical to achieving effective suture cut-off. If, on the one
hand, the value for inclusive angle X is below a certain minimum
(which depends upon the structural/mechanical properties of the
material from which the needle is fabricated and can be readily
determined in a given case by simple and routine testing), the slope
of the socket entrance will be too steep for the needle material
in the vicinity of the socket entrance to withstand the force of
the tensioned cutting movement which is employed to sever the suture
upon the circumferential cutting edge. If, on the other hand, the
value for inclusive angle X exceeds a certain maximum (again, as
in the case of the minimum value of X, a variable which depends
to some extent upon the nature of the material from which the needle
is fabricated and is readily determined for a specific needle construction
by simple, routine testing), the slope of the socket entrance will
be too shallow to provide an effective cutting edge. For surgical
needles manufactured from any of the stainless steels which are
commonly used for the construction of such needles, the value of
inclusive angle X is advantageously on the order of from about 90.degree.
to about 120.degree. and preferably is from about 95.degree. to
about 105.degree.. The needle can possess any appropriate shape,
e.g., it can be straight or it can possess a largely curved configuration.
Typical needle dimensions for a variety of suture sizes are set
forth in the following table.
TABLE __________________________________________________________________________
Needle Dimensions Socket Suture Needle Diameter, Socket Size Suture
Diameter Diameter, thousands of an Depth, Designation mm inches
inches inch (mils) inches __________________________________________________________________________
6-0 0.070-0.099 0.0026-0.0039 0.013 6.4-7.0 0.030 5-0 0.10-0.149
0.0039-0.0059 0.015 8.8-9.6 0.035 4-0 0.15-0.199 0.0059-0.0078 0.017
10.2-11.0 0.042 0.022 3-0 0.20-0.249 0.0079-0.0098 0.024 12.5-13.5
0.050 0.039 2-0 0.030-0.339 0.0118-0.0133 0.026 15.2-16.2 0.057
0.039 0.050 1-0 0.35-0.399 0.0138-0.0157 0.039 18.2-19.2 0.060 0.044
0.050 1 .sup. 0.40-0.499 0.0157-0.0196 0.039 21.2-22.2 0.070 0.044
0.050 __________________________________________________________________________
As shown in the apparatus of FIG. 2A, drilling unit 20 is provided
as a fluted drill bit 21 held in spindle 22 of a high speed motor
23. Spindle 22 should be capable of holding drill 21 with considerable
accuracy, e.g., with a maximum positional variation of no more than
about 0.00015 inches. The drill together with its motor is supported
upon a linear bearing member 24 which permits movement of drill
21 toward and away from the rear face of a socketed needle, e.g.,
with a straight line accuracy of at least 0.0005 in./in. of travel,
as shown in FIG. 2D.
As shown in FIGS. 2B-D, needle receiving and holding collet 30
possesses a central bore 31 extending its full length for receiving
the socketed end of a surgical needle. The collet possesses three
slots 34a, 34b and 34c extending from its front face 33 to rear
face 32 along conical shaped wall 35. These slots enable the collet
to convert an axially directed force exerted against its rear face
32 to a circumferentially compressive force exerted against the
blunt end of a needle present within bore 31 whereby the needle
is held firmly and accurately in place within the collet for the
subsequent circumferential suture-cutting edge-forming operation
(as well as any optional socket forming operation). Collet holder
40 functions as a support frame for collet 30 and orients and guides
the axial movement of the collet upon activation of locking ram
50. Opening 41 in collet holder 40 possesses a conical configuration
providing an accurate mating support surface for collet 30 and permitting
a limited degree of forward, axial movement of the collet therein
when locking ram 50 is set in motion. Key 42 along the periphery
of opening 41 of collet holder 40 cooperates with slot 36 in the
collet to precisely orient the collet and make certain that the
socketed end of the needle held within the collet is accurately
positioned relative to drilling tool 21. Clearance slot 43 is provided
on the collet holder in order to fully accommodate a curved needle
during the machining thereof.
To accomplish locking of the needle within the collet and locking
of the collet within its holder, a vertical movement of locking
ram 50 against the upwardly sloping surface 37 of rear face 32 of
collet 30 causes an axial forward movement of the collet within
opening 41 of collet holder 40. Activation of locking ram 50 results
in the application of an amount of force against collet 30 which
is sufficient to slightly compress the sections of the collet as
defined by slots 34a, 34b and 34c thereby securely locking the needle
in place for drilling.
The geometries of those surfaces of collet 30 collet holder 40
and locking ram 50 which come into mutual contact during the locking
step are important to achieving effective and accurate locking.
Thus, the forward face 51 of locking ram 50 is so shaped as to present
a downwardly sloping angle, in the embodiment shown, 5.degree.,
corresponding to the 5.degree. angle of upwardly sloping surface
37 formed on the rear face 32 of collet 30. As the driving ram moves
upwardly along a vertical axis which is perpendicular to the longitudinal
axis of the collet, the resulting engagement of mating surfaces
51 and 37 forces collet 30 forward within the collet holder, the
9.degree.30' slope of collet wall 35 engaging the 9.degree. wall
44 of collet holder 40. The slightly greater angle of wall 35 of
collet 30 relative to that of wall 44 of collet holder opening 41
results in the application of a transversally directed spring-like
compressive force against collet 30 upon activation of locking ram
50 which firmly locks the needle in place.
When locking ram 50 is lowered, i.e., returned to the unlocked
position, release of the compressive force against collet 30 results
in rearward movement of the collet within collet holder 40 accompanied
by a rearward ejection of the needle, now possessing a circumferential
suture-cutting edge, from the collet bore.
In the embodiment shown, positional needle tolerance in the locked
condition of the apparatus is held to a maximum deviation from the
longitudinal axis of the needle of not more than about 0.00025.degree..
Thus, the apparatus of this invention makes it possible to obtain
very accurate positioning of the blunt end of the needle relative
to the drill and to maintain this position throughout the socket
and circumferential suture-cutting edge-forming operations. In the
enlargement of the tip of drill 21 shown in FIG. 2B, the included
angle formed by the sloping surfaces of the drill is established
so as to define the value of inclusive angle x of the slope of the
socket edge. In the embodiment shown, this angle is set at 100.degree..
During the cutting edge forming operation minute metal shavings
or particles may tend to lodge within the socket. Prior to inserting
the suture within the socket, it is preferred to remove these shavings
employing any effective technique, for example, an ultra sonic cleaning
operation. |