WO1992019163A1

WO1992019163A1 - Blade holder

Info

Publication number: WO1992019163A1
Application number: PCT/GB1992/000794
Authority: WO
Inventors: William John Hoskin
Original assignee: Micra Developments Limited
Priority date: 1991-05-01
Filing date: 1992-04-30
Publication date: 1992-11-12
Also published as: GB9109347D0; GB2255926A; AU1671492A

Abstract

The surgical blade holder (4) has a pair of arms (6, 8) pivotally interconnected by a pivot (10) and each terminating in a finger (6B, 8B). One finger (8B) has a pair of locating pins (12, 14) for locating a slotted blade (2) on its surface. By closing the two fingers in a scissor-like action, the blade (2) becomes trapped between the two fingers (6B, 8B). A cam (26) acts on the two arms (8, 6) adjacent their distal ends to move them apart in a direction normal to the direction of angular displacement as the fingers move into superimposition with one another. The facing surfaces are so profiled that as they bend towards one another in response to the displacement of the distal ends of the arms away form one another, they cause the blade to bend out of its plane so as to secure a better gripping action on the blade.

Description

BLADE HOLDER

The present invention relates no blade holders. Cutting tools such as scalpels used for surgery and knives used by artists, model markers, and engineers often comprise a holder into which replaceable blades can be mounted.

In the case of a scalpel, the holder comprises a head portion projecting from the end of a handle portion. The head portion is in the form of an elongate rib having guide grooves in opposite flanks. The scalpel blade has a central slot of enlarged width at one end which is stepped down to a narrower width at the other end. In operation the wider portion of the slot is fitted over the rib and the blade is slid towards the handle to cause the sides of the narrower portion of the slot to engage the guide grooves. In order to slide the sides of the narrower portion fully home into the grooves, the blade must be bowed out of its plane since the blade beyond the wider portion of the slot must pass over the top of the rib while the narrower part of the slot is constrained in a plane located below the top of the rib. Force

therefore has to be used to bend the blade (which is naturally resilient) and to overcome the friction needed to slide the blade along the grooves.

Once the narrower sides of the blade slot have been pushed fully home into the grooves the end of the blade beyond the wider portion of the slot can drop into a recess in the surface of the rib. The bottom of the recess lies in a plane intermediate the plane containing the top of the rib and the plane of the grooves. The blade is thus held bent slightly out of its plane under its own resilience. This bending of the blade ensures that it is rigidly held by the blade holder. To release the blade, the blade must be lifted out of the recess and pushed back along the grooves. Again a certain amount of force is necessary. The force needed to load or unload a blade by hand is hazardous, and there is a high risk of the surgeon cutting himself on the cutting edge of the blade. The hazard is magnified in surgery since

contamination of the cut by the AIDS virus and other dangerous organisms and substances becomes possible.

Tools can be used to load and unload blades but this involves extra expense and equipment and adds to the complexity of the operation of loading and unloading blades.

Slotted blades and holders of this type are sold by Bard-Parker, Swann Morton and Feather Safety Razor Co Ltd.

It is an object of the present invention to provide an improved blade holder.

According to the invention there is provided a blade holder comprising a pair of arms each terminating in a finger, the arms being pivotally interconnected so that the fingers can be angularly displaced from a position in which the end portions thereof are laterally spaced, to a position on which they are superimposed one upon the other, the facing surfaces of the end portions when superimposed being sufficiently spaced to

accommodate a slotted planar blade of predetermined thickness, locating means on the facing surface of one said end portion for engaging the slotted blade to locate the blade in a predetermined position on said surface, and cam means associated with the arms on a side of the pivotal point remote from said fingers, to cause said arms to separate in a direction normal to the direction in which they are angularly moved, as said fingers move from a spaced position to a superimposed position to thereby cause one said finger to bend towards the ether finger to grip the blade.

A surgical blade holder embodying the present invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which :

Figure 1 is a plan view of the blade holder open ready to receive a blade;

Figure 2 is a plan view of the blade holder closed with the blade loaded therein;

Figure 3 is a plan view of the lower arm of the blade holder;

Figure 4 is a plan view of the lower arm of the blade holder with a blade resting thereon;

Figure 5 is a side elevation of the lower arm of Figure 3;

Figure 6 is a side elevation of the blade holder closed (to an enlarged scale);

Figure 7 is an under plan view of the handle end of the upper arm of the blade holder of Figure 1; and

Figure 8 is a fragmentary view of a modified version of the two arms of the blade holder.

Figure 2 shows a surgical scalpel comprising a surgical blade 2 and a blade holder 4. The blade holder 4, as shown more clearly in Figure 1, comprises a

relatively thick upper arm 6 and relatively thin lower arm 8 pivotally interconnected by a rivet 10.

The two arms have a generally similar profile and can be moved between a closed position in which the two arms lie one on top of the other and an open position in which the two arms adopt a cruciform configuration in the manner of a pair of open scissors.

Each arm 6 and 8 has an elongate handle portion 6A and 8A to one side of the pivot 10 and a slender finger portion 6B and 8B to the other side of the pivot

10.

The surface of the finger 6B which faces the finger 8B (when the two fingers are superimposed) is planar, while the facing surface of finger 8B is stepped. Upstanding from the stepped surface are two posts, a small diameter post 12 and a large diameter post 14. The stepped surface can be more clearly seen in Figure 5. As shown when moving in a direction away from the pivot 10 towards the end of the finger 8B there is a step 16, the surface then slopes downwardly at an angle of at least ¼º and preferably ½° towards the large diameter post 14.

From the post 14 to the end of the finger the surface is level.

The handle portions 8A and 6A are provided with respective recesses 8C and 6C on opposite sides so that by squeezing the holder 4 from opposite sides in the regions of the recesses, the two handle portions can be moved from the superimposed state (see Figure 2), to a slightly open state.

The surface of the handle portion 8A which faces the handle portion 6A (when the two handle portions are superimposed) has a part-spherical recess 20 with

tapering grooves 22 and 24 leading from the recess 20 to opposite sides of the handle portion. The facing surface of the handle portion 6A (see Figure 7) has a part- spherical projection 26 which is arranged to engage one or other of two grooves 22 and 24 of converging cross- section and be guided into the recess 20 during closure of the two arms 6 and 8.

In operation, with the two arms 6 and 8, open as shown in Figure 1, a surgical blade 2 is placed on the stepped portion of the finger 8B (see Figure 4). As shown in Figure 4, the blade has a cutting edge 30 and a central slot 32. The slot 32 is narrower towards the cutting edge 30 and wider at the opposite end. The width of the slot at the narrow end just exceeds the diameter of the small diameter post 12 and the width of the slot at the wider end, just exceeds the diameter of the large diameter post 14. Thus when the blade is placed on the stepped portion of the finger 8B, it is loosely held in place. The height of the posts 14 and 12 is smaller than the thickness of the blade 2, and the blade 2 because of the sloping portion 18, slopes slightly downwardly towards the cutting edge. When the two arms 6 and 8 are closed with the blade in the position shown in Figure 4, the finger 6B wipes across the upper surface of the blade. During the last stage of closure, the projection 26 engages one of the grooves 22 or 24 and is guided into the recess 22. The diameters of the projection 26 and the recess 20 are such that the handle portions 6A and 8A are moved apart at their distal ends, and in so doing, introduce a bending moment in the arm 8, which, because it is thinner than arm 6, flexes away from the arm 6 (see Figure 6). This causes the finger 8B to bend and press against the blade 2 so that the blade is deformed out of its plane against its own resilience.

This action firmly holds the blade between the fingers 6B and 8B so that a surgeon can incise without fear of the blade shifting relative to the fingers. To increase friction, the facing surfaces of the fingers may be roughened or treated with a hard material, such as tungsten carbide. The rough material, such as tungsten carbide serves both to improve the grip on the blade, is wear resistant and resists relative movement between the arms of the blade holder when they are closed.

In the blade holder of Figure 1 the two arms 6 and 8 are imprisoned by a rivet. In the modification shown in Figure 6 the two arms are separable and can be locked together in a pivotal manner with the aid of a keyhole slot 40 in the arm 8 and a headed screw 42 or other projection in the arm 6. In this manner proper sterilisation of the knife holder can take place.

The knife holder can be made of plastics, stainless steel, titanium or aluminium.

It will be appreciated that the profile of the facing surfaces of the fingers, in conjunction with the cam action on the handle portion, both act in a sense to bend the blade out of its own plane. This causes the blade to bear more heavily against its contacting

surfaces. This in turn increases the grip on the blades.

It will be appreciated that the profile of the facing surface need not have a sloping surface as

described here in order for the flexing of the blade to take place. Any profile which is different from the rest of the surface sufficient to bend the blade out of its plane will serve to enhance the grip on the blades.

In the specification the term 'slotted blade' is intended to encompass any blade including an opening which can be engaged by locating means on the facing surface (usually a pin) to locate the blade in position but allow the blade to flex slightly. In practice most of such blades will have an elongate slot as illustrated since there are many of these commercially available.

Claims

1. A blade holder comprising a pair of arms each terminating in a finger, the arms being pivotally interconnected so that the fingers can be angularly displaced from a position in which the end portions thereof are laterally spaced, to a position on which they are superimposed one upon the other, the facing surfaces of the end portions when superimposed being sufficiently spaced to accommodate a slotted planar blade of

predetermined thickness, locating means on the facing surface of one said end portion for engaging the slotted blade to locate the blade in a predetermined position on said surface, and cam means associated with the arms on a side of the pivotal point remote from said fingers, to cause said arms to separate in a direction normal to the direction in which they are angularly moved, as said fingers move from a spaced position to a superimposed position, to thereby cause one said finger to bend towards the other finger to grip the blade.

2. A holder according to Claim 1, wherein at least one region of one of the two facing surfaces being profiled differently from the remainder of the surface, so that when one said finger is bent towards the other finger it urges said blade against said differently profiled region to cause said blade to flex out of its plane to increase the hold on the blade.

3. A holder according to Claim 1 or to Claim 2, wherein said locating means comprises a pair of spaced posts upstanding from the facing surface of said one end portion.

4. A holder according to any one of Claims 1 to 3, wherein said cam means comprises a part-spherical

projection on one said arm and a recess and a guide groove leading to said recess on said other arm.

5. A holder according to any one of Claims 1 to 4, wherein said arms are of substantially similar profile so as to form a uniform handle when superimposed upon one another, one said arm having a recess on one side and the other said arm having a recess on the other side so that when the handle is squeezed across said recesses the two arms will be angularly displaced apart by an amount sufficient to enable the cam means to disengage.

6. A holder according to Claim 2 or any on of Claims 3 to 5 as dependent upon Claim 2, wherein said profiled region is inclined by at least ¼ ° with respect to the remainder of the surface.

7. A holder according to Claim 2 or to any one of Claims 3 to 5, wherein said profiled region is inclined by at least ½° with respect to the remainder of said surface.

8. A holder according to any preceding claim, wherein the said facing surfaces are roughened to

increase friction.

9. A holder according to any one of Claims 1 to 7, wherein said facing surfaces are coated with a material having a high frictional resistance.

10. A holder according to any preceding claim,

wherein one of said arms is provided with a keyhole slot and the other of said arms is provided with a headed pin to engage said keyhole slot and be moved to a position in which it becomes imprisoned therein to form said pivotal interconnection between said arms.

11. A blade holder substantially as hereinbefore described with reference to the accompanying drawings.