US2943650A - Device for tensing, twisting, and severing wire - Google Patents

Description

July 5, 1960 Rs. RUBIN DEVICE FOR TENSING, TWISTING, AND SEVERING WIRE Filed July 19, 1956 INVENTOR PAUL S. RUBIN ATTORNEY U i States atent Paul s. Rubin, Baltimore, Md. (910 S. Fairfax Ave., LosAngeles 3'6, Calif.)

Filed July 19, 1956, Ser. No. 598,957

6 Claims. (Cl. 140-119) This invention relates to a wireworking device and more particularly to an instrument or tool for tensing, twisting and severing wire. The invention isintended for use primarily in performing the foregoing Operations upon substantially side-by-side lengths of wire which are fixed at one end or at points along their length. The invention may be utilized to form a tight loop of wire about an object and to twist together and sever the free ends of the wire. The principles of the invention are described and exemplified herein by reference to a surgical instrument embodiment, but it will be apparent to those skilled in the art that the invention is applicable to other fields, such as commercial wireworking, as well.

In orthopedic surgery it is frequently necessary to join pieces of bone, as for example, in the setting of severe fractures or in performing bone grafts. In such operations,'a conventional surgical procedure requires that a piece of wire be looped about or threaded through holes inthe sections of bone to be joined and that the endsof the wife he twisted together to tighten the loop .and se-' cure it to the bone. The instrument commonly employed for performing these functions is essentially a plier, which the physician manipulates to grip the free ends of the wire which has been pulled around the bone and twist them together in a conventional manner. In this manipulation, the slack portion of the loop is taken up and tension is produced by twisting the free ends about each other, so as to shorten the circumference of the loop. The elasticity of the wire employed in this or in any similar application is such that the'necessary degree of tension approaches the tensile strength of the wire. It is a common observationof various artisans having occasion to twist wire loops with tools that the degree of latitude between the point of tight closure of the loop gripping an object and the point of breaking the wire is often only a single turn of 36() degrees or less, depending on the rigidity of the object enclosed by the loop. Considerable practice and skill is necessary to form a tight loop of wire, and even those skilled'in the art find this difficult to achieve consistently at first. This is especially the case in wire fixation of bone in surgical procedures. In attempting to obtain and secure a tight loop of wire, the physician frequently twists the wire too much, causing the wire to break at its point of maximum stress. Unfortunately, with conventional instruments and techniques, this point lies right at the loop, where the twist begins, and when the wire breaks, the twisted portion is severedfrom the loop, and the loop opens. After such an occurrence, the loop is, of course, valueless, and it must be removed and another loop put in its place. The placement of the wire around the bone to form the loop is ',a-difficu1t and time-consuming procedure because of the proximity of the tissues surrounding thebone, and it is very unfortunate when the first loop does not perform the function desired. The need for preventing the prolonging of such operations is self-evident. Accordingly', it is a principal object of the present'inven'tion 2,943,650 Patented July 5, 1960 to provide a device which overcomes the deficiencies of the prior art.

More specifically, it is a principal object of the invention to provide a device which tenses, twists, and severs wire in an accurately predetermined and controlled manner.

Another object of the invention is to provide a device for twisting together substantially side-by-side lengths of wire and for severing the wire at a predetermined point.

A further object of the invention is to provide a device for tensing wire sufiiciently to remove kinks, yet insufficiently to break the wire.

A further object of the invention is to provide a device for twisting wire in a controlled manner and for indicat ing when a predetermined amount of tension has been produced.

A further object of the invention is to provide a device for tensing and twisting together substantially side-by-side lengths of wire, accomplishing the said two functions as independent manipulations, or as controllably dependent manipulations.

An additional object of the invention is to provide a device for tensing and twisting wire, for resiliently controlling and for partially relieving the tension which builds up during the twisting so as to ensurerthat the wire breaks at the desired degree of tension, and for twisting the wire until it breaks automatically at the desired degree of twisting.

The foregoing and other objects of the invention and the manner in which these objects are accomplished will become more apparent in the following detailed description of the invention taken in conjunction with the accompanying drawing wherein:

Figure 1 is a perspective view of a preferred embodiment of the invention illustrated in use;

Figure 2 is an exploded view of the device of the invention;

Figure 3 is a partly sectional view of a portion of the device of the invention illustrating how the wire is pp Figure 4 is an endview of a part of the device of the invention as seen in the direction of arrows 4-4 in Figure 2;

Figure 5 is an end view of another part of the device of the invention as seen in the direction of arrows 5-5 in Figure 2; I Figure 6 is an end view of still another part of the device of the invention as seen in the direction of arrows 6-6 in Figure 2; and

Fignre7 is a sectional view of the tip of the device of the invention in conjunction with an adjacent wire twisting element and illustrates how the wire is threaded into the device.

The device of the invention may be employed in the forming of loops as described above, in which case the lengths of wire to be twisted together form one continuous piece, or it may be utilized to tense, twist, and sever separate lengths of wire arranged substantially side-by side. Briefly, in its preferred form the device ofthe invention comprises a handle portion which is constructed so as to grip the substantially side-by-side lengths of wire at points spaced from the object to which the wire is to be attached and a twisting element arranged to engage the wire near the object and to rotate so as to twist the lengths of wire together. The wire gripping portion and the twisting element are coupled by a coil spring through which a tensile force may be applied to the'wire when the spacing between the gripping portion and the twisting element is increased and through which torque may be applied to the twisting element from the gripping portion so as ;to twist the wire. In addition, the spring indicates the order of magnitude of the tensile force applied.

In a preferred embodiment, the device of the invention includes, referring to Figure 2, a wire gripping portion having a handle part 12 and a hand wheel 14, a head portion including a twisting element 16 associated with a tip 18, and a coil spring 20 associated with a pair of short tubes or sleeve elements 22, 24 arranged to couple the ends of the spring to the gripping portion 10 and the twisting element 16. The parts of the invention-may be formed of anysuitable material, such as steel or'brass, which may be chrome plated, if desired.

The gripping member 10 comprises a sleeve having a threaded lower portion 26 formed with a key-way 28. Hand wheel 14 is provided with internal threads which mesh with the threads of portion 26. Thus, as the hand wheel is rotated, it reciprocates along the threaded portion 26. The upper portion of the sleeve is tapered as indicated at 30 and is provided with a pair of diametrically opposite V-notches 32 (see Figure 3). The intermediate portion 33 of the sleeve has a disc-like stop 34 and a pair of keys 36.

Handle piece 12 is formed as a sleeve having an integral hand wheel 38. This sleeve has a pair of diametrically opposite slots 40 (see Figure 3) which are narrowed at their uppermost extremities as indicated at 42. The internal diameter of sleeve 12 and the external diameter of the intermediate portion 33 of sleeve 10 are proportioned so that sleeve 12 may slip upon the intermediate portion 33 and come to rest against stop 34.

The coil spring 20 is frictionally held upon its sleeve elements 22 and 24 and tendsto engage the sleeve elements more tightly when a torsional force is applied between the respective elements in the direction causing contraction of the radius of the helix. The spring may be disengaged from its sleeve elements, if desired, by applying a torsional force in the opposite sense expanding the radius of the helix. Sleeve element 22 has its internal diameter proportioned with respect to the external diameter of the threaded portion 26 of sleeve 10 so that sleeve element 22 may slide upon the threaded portion 26. Element 22 is provided with an internal key 44 (see Figure 4) which slides along key-way 28 and prevents rotation of sleeve element 22 with respect to the threaded portion 26. Each of sleeve elements 22 and 24 has an enlargement 46, 48 at its end to prevent the spring 20 from slipping otf of the ends of the respective sleeve elements.

The twister element 16 may be formed as a short sleeve having the diameter of its external surface proportioned to allow it to slip within the internal surface of sleeve element 24. The twister element is provided with an external key 50 which is received within a radial notch 52 formed in the enlargement 48 of sleeve element 24. (See Figures 5 and 6.) The twister element may have an integral enlargement 52a which engages the enlargement 48 of sleeve element 24 and serves as a stop. A pin 54 fixed across the interior of sleeve 16 serves as the key of the twisting element.

The tip 18 may have a generally hemispherical shape an may be formed with a short integral sleeve portion 56. The external diameter of sleeve portion 56 is so proportioned with respect to the diameter of the lower part of the bore through the twister element 16 that the short sleeve 56 fits rotatably within the twister element, with the upper surface 58 of the tip abutting the enlargement 52a. The bore of the sleeve portion 56 may taper down to a small bore 60 near the bottom of the tip (see Figure 7).

The use of the device of the invention will now be described in connectionwith the forming of a loop of wire 63 about an object 62, as shown in Figure l. The piece of wire to be looped is first pulled around the object 62, and the free-ends 65 of the wire, which now form substantially side-by-side lengths 64, are threaded through the device of the invention. To simplify the threading, the parts of the invention are made freely separable so that the lengths of wire may be easily passed in succession through the tip 18, the twister element 16 on opposite sides of pin 54, sleeve elements 22 and 24 and coil spring 20, and sleeve 10, and the parts may be assembled as the threading proceeds. The instrument is slipped down the wire until the tip 18 engages the object 62, and the slack wire is pulled through the instrument. The free ends of the wire are then bent into and over the V-notches 32. The handle 12 is then slipped over the sleeve 10 with the keys 36 moving into the slots 40, assuring correct alignment of slots 42 with respect to V-notches 32. The free ends of the wire then extend through the narrowed portions 42 of the slots as shown in Figures 1 and 3 and are tightly gripped between the sharp inner edges of the narrowed slots 42 and the tapered outer surface of the upper sleeve portion 30. The wire is acutely angulated in passing through the V-notches 32, impinging on the sharp corners of these notches, at both inner and outer edges. As tension on the wire is increased, as described below, it is drawn more tightly into the V-notches because of the snubbing action of narrowed slots 42 against the tapered outer surface of sleeve 30. The combined efiect of the slots 42 and V-notches 32 is that of wedging the acutely angulated portions of the wire into the V-notches, resulting in a grip which cannot slip and which increases its hold and security as the tension on the wire increases. The V-notches 32 may be wide enough to accommodate any of the many diflerent wire sizes which may pass through the bore 60 in the tip 18. With most wire sizes, the clearance between the handle 12 and the tapered portion 30 of sleeve 10 is insufiicient to allow the handle to slide all the way down to the stop 34. The gripping portion of the device may be made to accept any desired range of wire size by varying the length and width of V-notches 32 and slots 42, with commensurate modification of the length and degree of taper of the upper portion 30 of sleeve 10 to provide the necessary clearance for the maximum diameter wire.

In order to tense the wire, remove all kinks, and cause the loop to be pulled tightly around the object 62, the hand wheel 14 is rotated in the proper sense to cause it to move downwardly along the threaded portion 26 and to push the sleeve elements 22 and 24, the coil spring 20, the twister element 16, and the tip 18 away from the gripping portion 10. The spacing between the tip 18 and the gripping portion 10 is increased until all the slack in the wire is taken up within the increased length of the device, and tip 18 impinges on the points of closure of the wire loop in close contact with object 62. Further rotation of the hand wheel 14 produces progressive compression of the coil spring 20, with concomitant progressive tension of the wire between the object 62 and V-notches 32. As the tension in the wire is still further increased, coil spring 20 deflects to one side under compression, as shown in Figure 1. The coil spring thus not only acts as a resilient link in the chain of elements applying the tensile force to the wire, but also serves to indicate when a predetermined tensile force has been applied. During the application of the tensile force to the wire, the instrument may be tilted back and forth slightly, applying additional tension to the wire loop by leverage of tip 18 against object 62, so as to straighten any remaining kinks and ensure a tight fit between the loop and the object 62. Any remaining slack so extracted from the wire loop is automatically drawn up within the device by the tension of coil spring 20.

When the wire has been stretched to the desired degree in the manner described above, it is ready for twisting and severing. The hand wheel 14 is now rotated in the opposite sense so as to reduce the tension to the point where the coil spring 20 is substantially straight again. Then the hand wheel 38, which previously has been held fixed, is rotated either clockwise or counterclockwise, as preferred, to form the twist in the Wire. The entire device rotates as a unit integral with hand wheel 38; the torque applied to the latter is transmitted by engagement of keys 36 with the edges of slots 40 to the sleeve and by the key-way 28 to the key 44 and sleeve element 22. The torque is then transmitted from the sleeve element 22 to the coil spring 20 and from the coil spring to the sleeve element 24. The twister element 16 including the pin 54 is caused to rotate by engagement of key 50 in notch 52. The tip 18 may rotate by the force of friction due to contact with stop 5211, or, it may be manually constrained to remain stationary, if preferred, causing stop 52a of the twister element 16 to rotate on surface 58. As the hand wheel 38 is rotated the torque is applied by pin 54 to the lengths of wire 64. The twisting action takes place between two foci, one being stationary at the object 62, the other being rotatable at pin 54. The distance between the said 2 foci is kept constant by the abutment of tip 18 against stop 52a of the twister element 16. When wires under tension are thus intertwined along a segment of fixed length, the first twist is generated at a mid-point equidistant from the points of application of torque. Successive twists extend equally upward and downward toward the points of application of torque at pin 54 and object 62, respectively. The frequency of the spacing of successive windings follows a gradient, exhibiting a minimum at the midpoint, and a pair of maxima at the ends of the twisted segment. Thus a pair of intertwined helices is generated, which are tightest at their midpoints and loosest at their ends. With each successive twist, each coil of the helices is further tightened. The said helices span a constant distance already described, hence do not contract with increasing tension; instead, each draws additional wire into its span. These increments of wire are obtained at the expense of the straight 'side-by-side lengths of wire by the latter sliding down on each side of pin 54. The said pin 54 thus automatically apportions the wire from the straight to the twisted segments, as required during operation of the device. The device automatically accommodates itself to the progressive shortening of the straight segment of wire by additional compression of the coil spring 20. This increases the tension on the wire but at the same time the resiliency of the spring prevents an excessively rapid build-up of tension such as obtains during the twisting of wire in a rigidly coupled system. The increased tension on the wire grows suflicient with continued twisting to cause spring 20 to bend again to one side. This degree of tension may be relieved by intermittently backing off the hand wheel 14, as indicated by the straightening of coil spring 20. As the twisting progresses, the number of turns which can be accommodated between the span of the helices is limited by the caliber of the wire. As the number of turns approaches the limiting value, the individual coils of the helices are less free to slip and rotate upon one another because of the closeness of their packing, so that the helices become progressively less resilient toward their midpoints. The application of further torque now causes a sharp increase of the stress on the wire, causing it to break at the point of maximum stress. The said point of maximum stress is always located at the midpoints of the helices because these are at the nodal point between a pair of torques acting in opposite sense along the axis of the helices. These forces are also redirected in part as a pair of torques acting in opposite sense along the axis of the wires and tending to twist each wire on its own axis. The resulting shearing stress on each wire is likewise maximal at the nodal point between the applied torques. The combined tensing and shearing strains finally exceed the elastic limit of the wire, producing a rupture at the predetermined nodal point. The broken ends produced by this type of rupture are uniformly smooth and free of sharp points or burrs. Since the point of rupture occurs at the nodal point, the wire loop is closed by a number of tightly Wound turns equal to onehalf the number of turns in the helices at rupture. Any desired number of turns may be obtained by selecting one of a number of sizes of tip 18 so as to appropriately vary the length of the twisted segment.

It will thus be apparent that the device of the present invention first tenses the wire so as to remove kinks and ensure a tight fit of the loop with the object, then twists the wire while carefully controlling the tension so as to obtain secure gripping and immobilization of the object encircled by the loop and prevent premature severing of the wire or breakage at the wrong point, and finally severs the wire at a carefully chosen location remote from the loop. If the steps outlined above are followed, a very tight loop will be obtained in every instance, with the break in the wire located at the predetermined nodal point of the twisted segment of wire. In essence, then, this device ensures that the tightest twist is always equidistant from the ends of the twisted segment, as opposed to conventional devices in which the tightest twist is always at the end of the twisted segment adjacent to the object. The manner of application and control of the forces which twist and break the wire to ensure the above result are different from that of any previous device for this purpose and constitute a cardinal principle of the invention. It has been found, moreover, that the broken edges of Wire which has been worked in accordance with the invention are much smoother than the edges obtained by the conventional wire twisting and severing methods.

While a preferred embodiment of the invention has been shown and described, it will be apparent to those skilled in the art that modifications may be made therein without departing from the principles of the invention, the scope of which is defined in the appended claims. The foregoing embodiment is, therefore, exemplary rather than restrictive of the invention and those embodiments which lie within the meaning and range of equivalency of the claims are included therein.

What I claim as my invention is:

1. A device for forming and closing a tight loop of wire about an object, comprising a tip having a passage into which the free ends of a piece of wire encircling said object may be passed, said tip being adapted to fit snugly against the wire at said object, a wire grip for gripping the free ends of the wire extending from said object, said grip being spaced from said tip in alignment therewith and movable toward and away from said tip, a compression coil spring having its respective ends coupled to said tip and said grip and resiliently biasing said grip away from said tip, a wire twisting element supported between said tip and said grip and slidably engaging the lengths of wire extending from said object, said wire twisting element and said grip being coupled for unitary rotary movement, a spring compressing mechanism coupled to one end of said spring and having a hand engaging element arranged to move said grip toward or away from said tip and vary the compression of said spring and the tension of said wire, and said grip having a hand engaging element separate from the hand engaging element of said spring compressing mechanism, permitting the grip to be rotated along with the wire twisting element to twist the wire between said tip and the wire twisting element and form a pair of intertwined helices extending in opposite directions from a point intermediate said tip and said twisting element, wire being drawn into said helices from between said twisting element and said grip, compressing said spring, whereby maximum twisting and tension is produced at said point, ensuring that breakage of the wire occurs predictably at said point to leave a length of twisted wire attached to the loop.

2. A device for forming and closing a tight loop of wire about an object, comprising a tip having a passage into which the free ends of a piece of wire encircling said object may be passed, said tip being adapted to fit snugly against the wire at said object, a rotary wire twisting element supported adjacent said tip and slidably engaging the lengths of wire extending from said object, a compression coil spring having one end coupled to said wire twisting element for rotary movement therewith, a wire grip for gripping the free ends of the wire extending from said object, said grip being spaced from said tip in alignment therewith and movable toward and away from said tip, said grip being coupled to the other end of said spring for rotary movement therewith, and a hand engaging element coupled to said wire grip for turning the same and thereby causing said spring and said twisting element t0 turn.

3. The invention of claim 2, said other end of the spring being coupled to said wire grip for reciprocation between said grip and said tip, and said wire grip having a spring compressing mechanism for reciprocating said other spring end.

4. The invention of claim 2, said spring being coupled to said wire twisting element andto said wire grip by the frictional force exerted by the turns of said spring when it is placed in torsion.

5. A device for forming and closing a tight loop of wire about an object, comprising a tip having a passage into which the free ends of a piece of wire encircling said object may be passed, said tip being adapted to fit snugly against the wire at said object, a wire grip for gripping the free ends of said wire, said grip being spaced from said tip in alignment therewith and movable toward and away from said tip, said grip having a threaded portion extending toward said tip with a nut threaded onto and movable along said portion, a wire twisting element supported adjacent said tip and slidably engaging the lengths of wire extending from said object, said wire twisting element and said grip being coupled for unitary rotary movement, a compression coil spring having its respective ends coupled to said grip and said tip and resiliently biasing them apart, the end of said spring coupled to said grip abutting said nut and being movable by said nut to vary the compression of said spring, and said grip having a hand engaging element separate from said nut, permitting the grip to be rotated alongwiththe wire twisting element to twist the wire between said tip and the wire twisting. element and form a pair of intertwined helices extending in opposite directions from a .point intermediate said tip and said twisting element, wire being drawn into said helices from between said twisting element and said grip and increasing the compression of said spring, whereby maximum twisting and tension is produced at said point, ensuring that breakage of the wire occurs predictably at said point to leave a length of twisted wire attached to the loop.

,6. The invention of claim 5, said spring having sleeves atits ends keyed to the threaded portion of said grip and to said wire twistingelernent, respectively.

References Cited in the file of this patent UNITED STATES PATENTS 904,863 Glass et a1. Nov. 24, 1908 1,141,977 Rogers June 8, 1915 1,469,711 'Bauwens Oct. 2, 1923 2,133,887 Beers Oct. 18, 1938 2,147,706 Kerr et al. Feb. 21, 1939 2,421,878 Gubser et al. June 10, 1947 2,492,560 Dullaghan Dec. 27, 1949 2,645,832 Lee July 21, 1953 FOREIGN PATENTS 432,847 Great Britain Aug. 2, 1935

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