Background Art Tissue sampling needles have a broad range of applications. Firstly, they are used to obtain tissue for analysis from patients, and particularly used to obtain sub-cutaneous tissue. Likewise, such needles may also be used for veterinary purposes. Secondly, tissue sampling needles are used to obtain tissue samples of dead tissue, especially meats intended for human consumption. With the advent of diseases such as mad-cow disease, the analysis requirements for meat prior to sale and especially export have become very strict. Sampling and analysis of the meat has become very extensive.

At present, tissue sampling needles have problems which restrict their use.

At present, tissue sampling needles are manufactured in a similar manner to the well-know hypodermic needles designed for the injection of fluid into the body.

Such needles comprise conventional stainless steel tubes and have a tip for insertion into the tissue. The tip is defined by an oblique end face to provide a sharp point at the end. However, the object of a needle used for the injection of fluid into the body is that it should cause minimal damage to the tissue in which it is inserted. This is at least partially achieved with a hypodermic needle by the provision of the oblique end face. During insertion, the sharp point at the end of the tip enables the tip to penetrate easily into the tissue. But further, the oblique face enables the tip to push a path through the tissue with relative ease because the oblique face acts as a wedge pressing the tissue apart while causing minimal damage.

In contrast, the object of a tissue sampling needle is to cause some damage to the tissue by cutting and removing a sample. To do this effectively, it is necessary that the tip is adapted to cause the tissue to be cut while the needle is penetrating into the tissue. As described above, a tip which is defined by an oblique end face is not adapted to provide this action effectively. In order that a tissue sampling needle having an oblique face can be effective, it must necessarily be of a significantly larger diameter than would otherwise be desirable so that the open mouth of the tip provides an effective cutting edge to the tissue.

However, the use of larger diameter tissue sampling needles causes other problems, including increased discomfort to the patient and risk of infection. This has been found to be even more the case for tissue sampling needles used for obtaining tissue samples from cattle, pigs or other animals with tough hide. In these cases, it has been found that it is necessary to use a needle which is of such a large diameter that there is a serious risk of the wound becoming infected after the sample is taken. As a result, tissue samples are only taken after the animal is slaughtered. This is a problem, in itself. If the carcass fails the analysis, it is no longer possible to take remedial action and the carcass must then be disposed of as an item of much reduced value.

Disclosure of the Invention Accordingly the invention resides in a tissue sampling needle comprising a hollow, tubular needle having a tip defined by an end face which is concave.

According to a preferred feature of the invention, the concave end face defines a plurality of points.

According to a preferred feature of the invention, the end face is defined by an edge extending between the points, the edge being of a concave configuration and of divergent cross-sectional profile to define a sharp cutting edge.

According to a preferred feature of the invention, said concave face is formed by multiple grinding operations upon the end of the tubular needle.

According to a preferred embodiment, said the concave face defines between two and four points.

According to a preferred embodiment, the needle is formed of stainless-steel tubing.

According to a further aspect, the invention resides in a meat-sampling apparatus, the meat-sampling apparatus comprising a syringe and a tissue sampling needle of the type as previously described.

The invention will be more fully understood in light of the following description of several specific embodiments.

Brief Description of the Drawings The description is made with reference to the accompanying drawings of which: Figure 1 is an isometric view of a tissue sampling needle according to the first embodiment; Figure 2 is an enlarged isometric view of a the tip end of the tissue sampling needle according to Figure 1; Figure 3 is an enlarged isometric view of a the tip end of the tissue sampling needle according to a second embodiment; Figure 4 is an enlarged isometric view of a the tip end of the tissue sampling needle according to a second embodiment; Figure 5 is an isometric view of a needle and syringe according to the third embodiment;

Figure 6a is a diagrammatic view of a tissue sampling needle in use in initial contact with the outer skin; Figure 6b is a diagrammatic view of a tissue sampling needle in use when it has commenced penetration of the skin tissue; Figure 6c is a diagrammatic view of a tissue sampling needle in use where the tip end has fully penetrated into the skin tissue ; Figure 6d is a diagrammatic view of a tissue sampling needle in use with a tissue sample held within the needle hollow after being withdrawn from the tissue; Figure 7 is a diagrammatic view of a tissue sampling needle in use in initial contact with the outer skin.

Detailed Description of Preferred Embodiments.

The first embodiment of the invention is directed to a tissue-sampling needle adapted to obtaining a tissue sample from a live body.

The tissue sampling needle 11 according to the first embodiment is shown in Figure 1. The needle 11 comprises a stainless steel tube 20 of conventional form having an insertion end in the form of a tip 21 and a support end 31, remote from the tip 21.

In the embodiment, the tip 21 is provided with a concave face to define a pair of diametrically opposed points 23 disposed around the periphery of the end face, where each of the points 23 is separated by an edge 22 of concave configuration where the edge 22 has a divergent cross-sectional profile to form a sharp cutting edge. The two points 23 are formed by multiple grinding operations upon the tip 21 of the tube to produce an end face that is concave and defines two points 23.

In use, the needle is preferably inserted substantially perpendicularly into the tissue. As shown in Figure 6a, initially, each point contacts the outer skin and

depresses it. As the needle is inserted further, the outer skin layer is punctured by the points, as is shown in Figure 6b. Thereafter, the needle is inserted somewhat further into the tissue so that the tip end is fully located within the tissue, as shown in Figure 6c. As it is being inserted, the edges between the points will act to progressively cut the skin. Because there are two points, one holds the skin tissue relative to the other so that the tissue cannot be displaced laterally during initial insertion of the needle tip in the way in which it can be displaced with a conventional needle. On the surface of the skin tissue being cut, the underlying tissue tends to be cut quite readily and as a result a cylinder of tissue is cut from the patient and whist being cut is guided by the two tips into the hollow of the cylinder as the needle is inserted to the desired depth.

Thereafter, the needle is withdrawn, drawing the cylinder of tissue with it, as shown in Figure 6d.

The needle is adapted to be associated with a syringe. The syringe 32 comprises a cylindrical chamber, a piston and a spout and is of conventional construction. The support end 31 is engaged with the spout of the syringe also in a conventional manner. The syringe is provided principally to enable a pressure differential to be exerted upon the sample held within the hollow of the needle after the needle has been withdrawn from the tissue. To facilitate the generation of the pressure differential the piston needs to be withdrawn some degree before the needle is inserted into the body. As the needle is inserted into the body the piston of the syringe is withdrawn further to reduce the air pressure within the syringe and thereby assist in drawing the tissue cylinder into the hollow of the needle. On withdrawal of the needle from the body the piston of the syringe is depressed to expel the tissue from the needle for analysis.

Alternatively, the syringe may be at least partially filled with a small quantity of an inert liquid such as sterile water to enable the sample to be expelled from the needle after withdrawal of the needle from the body. Optionally, the piston may be withdrawn somewhat immediately after the tip is just inserted into the tissue to thereby provide a reduced pressure within the syringe to further urge the tissue to be drawn into the hollow of the needle.

A second embodiment of the invention is illustrated in Figure 3 and a third embodiment is illustrated in Figure 4, Figure 5 and Figure 7. The second and third embodiments differ from the first embodiment only in that they have three points and four points at the tip end, respectively. These embodiments have an advantage over the first embodiment in that they tend to hold the skin tissue in two dimensions relative to the other points to facilitate the cutting of the skin and tissue.

As a result of using tissue sampling needles according to the embodiments, the diameter of the needles can be reduced significantly when compared with needles conventionally used for the same purpose. This reduces the tissue damage as well as the discomfort caused to the patient. When used in relation to the meat industry, an additional advantage is expected in that that tissue sampling needles formed in accordance with the embodiments enable the diameter to be reduced sufficiently in order that tissue samples obtained from live animals by the needles will result in reduced trauma to the skin which should reduce the risk of subsequent infection at the sample site. This increases the capacity to humanely test live animals and if they fail the analysis, to take appropriate remedial action to overcome the problem. This results in very significant savings by avoiding the discarding of carcasses that have failed the tests.

According to a further embodiment the tip of the needle has points of differing length. This is achieved by rotating the needle through unequal angular displacements between the grinding of the facets. For example, In the production of a two point tip, if the needle is caused to rotate through 170° instead of 180°, points of differing lengths will result. This is perceived to have advantages in special applications.

Needles according to each of the embodiments may be manufactured according to conventional technology. Using this technology, needles with two-point tips can be manufactured by a linear jig comprising a pair of parallel, flat plates between which a batch of needles are clamped, arranged adjacent one another

with their longitudinal axes parallel and with an end of each needle extending outwardly from the edge of the plates. A cylindrical grinding wheel faces the edge created by the row of needles supported by the jig. A first oblique face is ground on the tip of each needle by the jig being moved laterally relative to the grinding wheel, usually a number of times until the desired face is obtained. The jig is adapted to be indexed towards the grinding wheel after each pass.

Thereafter, one of the plates of the jig is moved relative to the other plate by a small amount in a direction perpendicular to the axes of the needles while maintaining some pressure on the needles to thereby cause each needle to rotate by 180 degrees between the two plates. The jig is caused to address the grinding wheel again to grind a second oblique face on the tip of the needle. The two points are thereby formed between the two opposed oblique faces and the facets defined around the periphery of the tip will have a cross section profile which may vary with a variation of grinding techniques. It is anticipated that it will be possible produce needles with tips having more than two points, for example three points may be produced by causing the needle to rotate by 120 degrees between successive grinding operations and four points may be produced by causing the needle to rotate by 90 degrees between successive grinding operations. However, it has been found that it is very difficult to control the degree of rotation of the needles sufficiently accurately using this technology and it is barely practicable even to produce two point tips using this method of manufacture. In addition, this technology is subject to other problems such as the needles moving in the jig causing a considerable failure rate.

Needles having multi-point tips may more accurately and more reliably be produced by a method of manufacture developed by the present inventor and described in International patent application PCT/AU2004/000090 lodged in the name of the same applicant on 23 January 2004. As has been described in that application, that invention discloses an apparatus for grinding the tips of needles which comprises a rotary jig. Needles are clamped between pairs of inner and outer clamping shoes and the tip presented to a grinding wheel in any of a number of different ways as described in the specification of PCT/AU2004/000090. The needles are then caused to rotate through the

predetermined angular displacement necessary for the required number of points, that is, for two points, rotation of 180°, for three points, rotation of 120°, for four points, rotation of 90°, etc. As is also described in that specification, production of the needle tips of the present invention by the apparatus disclosed in PCT/AU2004/000090 enables the manufacturer to select a grinding action which results in the peripheral facets 28 to be planar, convex or concave. This choice will affect the profile of the concave face of the tip and thus will affect the penetration or cutting properties of the tip.

Modifications and variations as would be known to the skilled addressee are considered to be within the scope of this invention and it should be appreciated that the present invention need not be limited to the particular scope of the embodiment described above.

Throughout the specification, unless the context requires otherwise, the word "comprise"or variations such as"comprises"or"comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.