METHOD OF MAKING A SURGICAL INSTRUMENT WITH HIGH CONTRAST MARKING

Abstract

A method of marking a surgical instrument with a symbol formed in or on a smooth surface comprises forming a symbol in or on a smooth surface of the surgical instrument; and forming a plurality of angled surfaces over at least part of the area of the symbol. The angled surfaces define a plurality of parallel ridges and grooves in the symbol. The steps of forming the symbol and forming the plurality of angled surfaces take place substantially simultaneously in a single step.

Claims

1. A method of marking a surgical instrument with a symbol formed in or on a smooth surface, the method comprising: forming a symbol in or on a smooth surface of the surgical instrument; and forming a plurality of angled surfaces over at least part of the area of the symbol, wherein the angled surfaces define a plurality of parallel ridges and grooves in the symbol; and wherein the steps of forming the symbol and forming the plurality of angled surfaces take plane substantially simultaneously in a single step.

2. The method of claim 1 wherein the symbol and plurality of angled surfaces are formed in a single molding step.

3. The method of claim 1 further including a step selected from the group of polishing or roughening the plurality of angled surfaces or the smooth surface to produce a different surface roughness in the plurality of angled surfaces compared to the smooth surface.

4. The method of claim 1 wherein the symbol and plurality of angled surfaces are formed in a single machining step.

5. The method of claim 4 further including a step selected from the group of polishing or roughening the plurality of angled surfaces or the smooth surface to produce a different surface roughness in the plurality of angled surfaces compared to the smooth surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0034] FIG. 1 depicts a top view of a tibial sizing guide according to a first embodiment of the present invention;

[0035] FIG. 2 depicts a bottom view of the tibial sizing guide of FIG. 1;

[0036] FIG. 3 depicts a cross-section through a vertical stroke of a four symbol marked on the tibial sizing guide of FIG. 1;

[0037] FIGS. 4A-4G are a series of photographs of example tibial sizing guides with debossed symbols containing ridges and grooves according to the present invention and prior art plain debossed symbols at a variety of viewing angles;

[0038] FIGS. 5-9 give examples of numeric debossed characters with ridges and grooves formed according to alternative embodiments of the present invention; and

[0039] FIG. 10 depicts a perspective view of a tibial keel punch according to another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0040] FIG. 1 depicts a top view of a tibial sizing guide 2 according to a first embodiment of the present invention. FIG. 2 depicts the tibial sizing guide of FIG. 1 from the bottom. The tibial sizing guide 2 comprises six separate tibial sizing guides 4, 6, 8, 10, 12, 14. Each tibial sizing guide contains a planar sizing element 16 extending from a shaft 18. The tibial sizing guides are joined along an axis 20 perpendicular to the plane of the sizing element 16. In use, the planar sizing element 16 is used to measure the size of a tibia during knee surgery. Each tibial sizing guide, 4, 6, 8, 10, 12, 14 is marked with a debossed symbol indicating the size it represents. In this case the symbol is a numeric character.

[0041] The debossed symbols are provided with a plurality of ridges and grooves, described in more detail below with reference to FIG. 3. For clarity in FIGS. 1 and 2, debossed symbols on the tibial sizing guide which include the plurality of ridges and grooves are marked in black.

[0042] FIG. 3 is a diagrammatic representation (not to scale) of a partial cross section through a vertical stroke of a four character in the embodiment of FIGS. 1 and 2. FIG. 3 depicts how the debossed symbol contains a plurality of ridges 22 and grooves 24 extending over the area of the debossed symbol. In this embodiment the depth of the trough of the grooves 24 is about 0.6 mm from the smooth surface and the height of the peak of the ridges 22 above the trough of the grooves 24 is about 0.1 mm. The peaks of the ridges 22 in this embodiment are therefore below the level of the surrounding surface 26 in which the debossed symbol is formed. In other embodiments different dimensions may be used as appropriate.

[0043] A single angled surface extends from the peak of each ridge 22 to the trough of each groove 24. In this embodiment the angled surface is a substantially planar facet 25. The angle between adjacent facets 25 is about 90. As can be seen in FIG. 3, in this embodiment the debossed symbol, and the trough of the grooves do not extend through the entire depth of the part of the surgical instrument in which they are formed. This means that the debossed characters are invisible from the underside.

[0044] The facets 25 forming the ridges 22 and the grooves 24 are preferably polished.

[0045] In use, the angling of the facets 25 relative to the surrounding surface 26 creates a combination of different specular reflection and shadows caused by incident light. In an operating theatre, incident light is generally from above, designed to illuminate the operating area evenly. This gives surgical lighting a directional quality that improves the enhanced contrast of the present invention under surgical lighting conditions. In use, the facets 25 create a pattern of reflection and shadow which alters the perceived shade of the debossed symbol relative to the surrounding surface.

[0046] FIGS. 4A-4G are a series of photos showing the improved contrast of a debossed symbol with ridges and grooves according to the present invention compared with a prior art plain debossed symbols. On the instrument on the right hand side of the photos a debossed symbol with ridges and grooves of the invention is depicted. On the left hand side, a conventional surgical instrument without the ridges and grooves in its debossed symbols is depicted. It can be seen how the debossed symbol of the invention on the right hand side instrument, including ridges and grooves, has improved contrast versus the prior art symbol at virtually all angles relative to an onlooker.

[0047] Although this embodiment has been described in terms of a tibial sizing guide, it will be appreciated that the improved contrast of the present invention is advantageous when applied to any surgical instrument, not just tibial sizing guides.

[0048] FIGS. 5-9 depict examples of debossed numerical characters according to further embodiments of the invention. To understand the effect of extending the debossed character through the entire depth of the component to be marked, FIGS. 5-9 depict numerical symbols debossed on a side visible to an onlooker at the bottom. At the top, debossed symbols formed on the opposite to the onlooker are depicted.

[0049] In FIG. 5 the grooves of the facets formed within the debossed numerical characters 28 do not extend through the entire depth of the material. Therefore, no evidence of the corresponding debossed characters marked on the underside of the example surface in FIG. 5 can be seen.

[0050] In the embodiments of FIGS. 6-9 the grooves extend through the entire depth of the component in which the debossed numerical characters are marked. The spacing between alternating pairs of facets either side of a groove which extends through the entire depth of the substrate is increased in the embodiment of FIG. 7 compared with FIG. 6, further increased in the embodiment of FIG. 8 compared with FIG. 7 and still further increased in the embodiment of FIG. 9 compared with FIG. 9.

[0051] FIGS. 6-9 show how, even when the troughs of the groove extend through the entire depth of the component and occupy a significant area of the numerical character, there is a low risk of confusing a character marked on the opposite surface with a character marked on the surface viewed by an onlooker.

[0052] In the embodiments of FIGS. 5-9, the details of the surgical instrument to which the debossed symbols are applied has not been shown. For example, the numerical characters depicted in these embodiments could be applied to the numerical markings on the tibial sizing guide of FIGS. 1 and 2, as well as any other surgical instrument. It will also be appreciated that the concepts of FIGS. 5-9 can be applied to any symbol and is not limited to numerical characters.

[0053] The present invention is preferably manufactured from injection moulded plastics material. In that case, the debossed characters and facets can be defined in a single injection moulding step. Other moulding processes may also be used. Alternatively, the debossed characters may be formed by machining. This can be useful when the surgical instrument is manufactured of other materials than plastics materials, for example, metal alloys. The invention can also be applied to ceramic materials. Other production processes may also be used, including casting, metal injection moulding, stamping or embossing.

[0054] A further embodiment of the invention is depicted in FIG. 10. This depicts a tibial keel punch having debossed symbols 30 provided on a curved surface 32. The construction of this embodiment is the same as described above, apart from the debossed symbols 30 are provided on a curved surface rather than a flat surface. The ridges and grooves defined by the angled surfaces 34 of the debossed symbols 30 are also curved, generally following the shape of the curved surface 32 if it were extended over the debossed symbol. The ridges and grooves defined by the angled surfaces remain parallel to each other.

[0055] To improve the contrast effect of the present invention it is preferred to use a lighter rather than a darker material so that the shadows and highlights produced by the facets create a greater difference in contrast. However, the invention still has an effect with all colours and shades.

[0056] While the above described embodiments have discussed debossed symbols, it will be appreciated that the construction and techniques discussed can equally be applied to embossed symbols, and will improve the contrast of an embossed symbol relative to a surrounding surface.