GB2214113A

GB2214113A - Wire twisting device

Info

Publication number: GB2214113A
Application number: GB8901380A
Authority: GB
Inventors: Sabhash Chandra Halder
Original assignee: BIO MEDICAL ENG
Current assignee: BIO MEDICAL ENG
Priority date: 1988-01-22
Filing date: 1989-01-23
Publication date: 1989-08-31
Also published as: GB8901380D0

Abstract

The device, for use in the tightening and twisting of a wire about a bone or the like in orthopaedic surgery, has first and second guide means 2a, 4a for receiving the respective ends of a loop of wire and arranged for rotation about an intermediate axis whereby the ends of the wire may be twisted about one another 40, and wire securing means e.g. a bar 20 arranged for movement away from the said guide means 2a, 4a for tightening said loop and towards the guide means during said rotation. The bar 20 is guided for movement along two posts 2, 4 caused by rotating a screwthreaded rod 16. This produces the initial loop tightening, with opposite rotation of the bar 20 with the posts 2, 4, for subsequent wire twisting. The wire is secured in grooves in the bar ends. <IMAGE>

Description

Wire Twisting Device The invention relates to apparatus for use in the tightening and twisting of a wire about a bone or the like in orthopaedic surgery.

It is sometimes necessary, in the repair of fractured bones, to encircle the bone with a loop of wire under considerable tension, and to secure the loop by twisting the ends of the wire together without relaxing the tension.

Inasmuch as the operation is normally required to be conducted on a living body under anaesthetic, it is of importance that the process shall be carried out quickly and because the twisted wire is intended to be left, at least for a time, within the body, it is also desirable that the wire shall be free from kinks or other irregularities. Accordingly, a light-weight apparatus has been devised to facilitate, and particularly to simplify and speed, the tightening and regular twisting of a wire about a bone or the like in an orthopaedic operation.

According to the invention there is provided apparatus for tightening and twisting a wire about a bone or the like comprising first and second guide means for receiving the respective ends of a loop of wire and arranged for rotation about an intermediate axis whereby the ends of the wire may be twisted about one another, and wire securing means arranged for movement away from the said guide means for tightening said loop and towards the guide means during said rotation.

Preferably the apparatus further comprise a pair of guide posts parallel to said axis, and a screwed rod rotatably mounted on the axis by means supported by said posts and provided with handle means for manual rotation.

The guide posts preferably incline towards one another at one end, and the guide means preferably comprise an aperture in each of the respective posts at said one end. Each aperture may be flared and may lead to a groove formed in the outer edge of its associated post where it inclines towards the other The wire securing means preferably comprises a member slidingly engaged with the guide posts and in thread engagement with said rod. The member may be a bar transverse to said guide posts and provided with terminal slots for receiving the ends of the wire. The slots may be tapered and parallel to the guide posts.

The bar may be provided with a plurality of parallel transverse V-section grooves, spaced along the slotted portion of the bar and formed in the sides and upper and lower faces of the bar so that the bases of the grooves intersect at right angles.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings of which: Fig. 1 shows the embodiment in front elevation and in use, Fig. 2 shows the embodiment in side elevation, and Fig. 3 shows the embodiment in end view As shown in the Figures, the apparatus comprises a pair of spaced guide posts 2,4 of smooth circular cross-section.

Near one end they support a cross-member 6 which is provided with a central bore 8. Towards, but less near the other end, the posts supports a further cross-member 10 which is also provided with a central bore 12, which is recessed from face 14 of the member to provide a wider bore 24 A rod 16 of generally circular cross-section, and having a larger diameter head 22 at one end, is rotatably mounted in the bores 8 and 12, the wider bore 24 accommodating the head 22. The bores are are suitably provided with sleeves of hard-wearing plastics material to reduce friction. From the cross-member 6 and towards the cross-member 10, the rod 16 is provided with a thread of low pitch.

The other end of the rod 16, that is to say the end remote from the cross-member 10, is provided with a handwheel 18 by means of which the rod may be turned manually in its bearings.

A transverse bar 20 is provided with spaced through bores 26 by means of which is slidable along the posts 2,4. The bar 20 also has a central bore which is threaded for engagement with the threaded portion of the rod 16 which passes through it. Thus by turning the rod 16 by means of the hand wheel 18, the bar 20 can be moved to and fro along the posts 2, 4, the direction depending on the direction of rotation of the wheel and the hand of the thread.

The ends of the bar 20 are rounded as shown in the Figures, and each is provided with a tapered slot 30 of such width as to correspond to the thickness of a range of the wires with which the instrument is intended to be used. The sides, and bottom and top faces of the bar exterior of the posts 2,4, are provided with V-shaped parallel grooves 32, again for accommodating the wire. In this embodiment the grooves in adjacent faces are aligned and have flat bases as shown in Fig. 2, intersecting at a sharp angle to minimise slipping of the wire. However, it within the scope of the invention that the grooves should be replaced by a single spiral groove and for the groove or grooves to have arcuate or even circular bases.

The posts 2,4, which as indicated above are parallel between the cross-members 6 and 10, extend beyond the cross-member 10, and the extension portions 2a, 4a, are inclined towards one another so that their extreme ends 34 are relatively close together. Although the posts 2, 4 are generally solid, a flared opening 38 in the each of the ends 34 leads to an open groove 36 in the outer face of one or other of the posts, and the grooves extend to where the posts become parallel.

In use of the instrument, a wire (shown in chain dotted line in Fig. 1) is formed into a loop around the bone (not shown) and the ends crossed over at 40 as shown. The ends of the wire are then entered into the respective openings 38 in the ends 34. The ends of the wire are then led along the grooves 36 and from thence, again shown in chain-dotted line, to the bar 20. The wires are inserted into the inwardly tapering slots 30 until the wire is gripped between the sides of the slot. The remaining portion of wire is then wound a few times round the ends of the bar, preferably engaging the grooves 32 and bending sharply from the slot to the first groove and also where the grooves in adjacent faces intersect. Finally the ends of the wires are returned to the slots 30 and the surplus wire is then cut off.It should be emphasised that the arrangement is intended to offer both speed and firmness of attachment of the wire.

The main gripping function is provided the the first entry of the wire into the tapered slot; the second, dependent to some extent on the resilience of the wire, being provided by the angular turn of the remaining portions of the wire particularly if these happen to fall into the grooves.

It may be convenient for the bar to be initially positioned somewhat nearer the cross-member 10 than shown in the Figure. Once the wire is secured about the bar 20 as described above, with minimal chance of slipping, the handwheel 18 is turned relative to the posts 2, 4 in such a direction as to move the bar 20, by thread action, towards the cross-member 6, which has the effects of drawing the instrument nearer to the encircled bone and tightening the loop about the bone.

When such tension has been applied to the wire as experience shows to be necessary and sufficient, the wheel 18 is held stationary and the bar 20 is slowly turned about the rod 16 in the opposite relative direction, that is to say in such a direction as to cause it to return towards the ends 34 of the posts 2, 4. The rotation of the bar causes the posts 2, 4 also to rotate about the central rod 16. This means that the ends 34 of the post extensions 36 also rotate relative to the crossing 40 of the wire loop.

If the initial crossing of the wires was effected in the correct way (a matter which it is thought will soon be learned by experience) the first 180-degree rotation of the bar will add a further twist to the crossed wires (instead of uncrossing them) and this effectively locks the tension in the portion of the wire surrounding the bone, and further rotations of the bar produces a twisted "tail" of wire as long as required.

It will be understood that as a length of wire is twisted about another a finite length of wire is consumed depending on the diameter of the wire. Accordingly, the pitch of the thread of the rod 16 is chosen, in relation to the thickness of the thickest wire to be used, so that as the bar 20 rotates, it moves towards the ends 34 to release just sufficient wire from the openings 38 as will be needed. If a fine wire is used, the twist will be somewhat looser, but still perfectly even as wire is fed to the twisting point from both sides in equal lengths. The result is that a twisted "tail" of perfect regularity can quickly be made without the danger of excessive tension causing the wire to break.

In an alternative embnodiment, not shown, the securing of the ends of the wire to the bar 20 is effected by the provision of two parallel slots instead of the single slot 30 at each end of the bar, and a peg inboard of each pair of slots.

The end of the wire is passed through one slot, is turned round the peg, and passed through the other slot. If necessary further turns of wire around the peg and/or bar can be made, but one tight curve around the peg proves a very effective securing of the wire.

Claims

1. Apparatus for tightening and twisting a wire about a bone or the like comprising first and second guide means for receiving the respective ends of a loop of wire and arranged for rotation about an intermediate axis whereby the ends of the wire may be twisted about one another, and wire securing means arranged for movement away from the said guide means for tightening said loop and towards the guide means during said rotation.

2. Apparatus according to Claim 1 further comprising a pair of guide posts parallel to said axis, and a screwed rod rotatably mounted on the axis by means supported by said posts and provided with handle means for manual rotation.

3. Apparatus according to Claim 2 wherein the guide means comprise an aperture in each of the respective posts at one end.

4. Apparatus according to Claim 3 wherein the guide posts incline towards one another at said end.

5. Apparatus according to Claim 4 wherein each aperture is flared and leads to a groove formed in the outer edge of its associated post where it inclines towards the other.

6. Apparatus according to any one of the preceding claims wherein the wire securing means comprises a member slidingly engaged with the guide posts and in thread engagement with said rod.

7. Apparatus according to claim 6 wherein the member is a bar transverse to said guide posts and provided with terminal slots for receiving the ends of the wire.

8. Apparatus according to claim 7 wherein the slots are tapered and parallel to the guide posts.

9. Apparatus according to claim 7 or claim 8 wherein the bar is provided with a plurality of parallel transverse Vsection grooves, spaced along the slotted portion of the bar and formed in the sides and upper and lower faces of the bar so that the bases of the grooves intersect at right angles.

10. Apparatus for tightening and twisting a wire about a bar or the like substantially as described with reference to the drawings.