IES85863Y1 - Cannula and cannula device for implanting an implant - Google Patents

Description

Cannula and cannula device for implanting an implant The invention relates to a cannula and a cannula device for implanting an implant. implantation devices are preferably used during the treatment of patients with tumours in order to introduce a medicament subcutaneously into the tumour patient. Small rods made from a biologically degradable synthetic material are produced as implants for this purpose. In the patient's body the implant delivers an active substance, which, for example, causes a reduction in testosterone and therefore a restriction of tumour growth. The degradation of the implant takes place through hyclroiysis owing to the natural water balance in the human body. The time taken for the delivery of the medicament in the patient's body typically extends over about four weeks.

An implantation device is used to introduce the implant into the human body. This usually consists of three functional parts, a cannula, which contains the implant, a cannula holder. which can be durably connected to the cannula, and an applicator, which administers the implant into the patient's tissue from the puncture cannula. The cannula holder and the cannula together form a cannula device.

In the prior art the implant is introduced in the form of small rods into the proximal opening in the cannula by means of tweezers and with the aid of a piston rod. Subsequently a solution of synthetic material is applied to the implant via the proximal opening in the cannula, which solution fixes the implant rod. This synthetic material solution can be introduced into the cannula in a predefined quantity in the form of drops using a metering pipette. The drop then lies proximally in front of the implant rod and adheres both to the inner wall of the cannula and also to the implant rod and hardens at ambient temperature. It therefore secures the implant rod against falling out of the cannula.

If an implant rod of this type is to be administered, then it is pressed against the hardened synthetic material drop with the aid of a rod piston engaging at the distal end of the implant rod, which hardened synthetic material drop is thus detached from the inner wall of the cannula and releases the implant rod.

This prior art includes the disadvantage that it is difficult to ensure a reproducible position for the synthetic material drop in the cannula. Furthermore, the surface of the implant rod over which the active substance is to be released is sealed to differing degrees by the synthetic material solution so that parts of the surface are at times not available for release of the active substance from the implant rod, which can dlsadvantageously lead to a non-uniform delivery of the active substance.

It is an object of the invention to create an improved cannula and an improved cannula device with an implant or for an implant.

This object is achieved by a cannula as claimed in claim 1. Advantageous developments of the invention are defined in the dependent claims.

A cannula comprises a proximal end, which is provided for insertion into tissue in which an implant is to be placed, and a distal end, which is provided for connection to a cannula holder. A bore for an implant extends from the distal end to the proximal end of the cannula. The present invention is based on the idea of providing a lateral opening to the bore between the proximal end and the distal end. Through this lateral opening an elastic structural element can exert a force perpendicularto the axis of the cannula onto an implant in the bore. The implant is fixedly clamped in the cannula by the force exerted by the elastic structural element. Alternatively the elastic structural element engages through the opening into a groove or another recess in the implant in order to fixedly hold the implant. According to a further alternative the elastic structural element partially displaces the bore and/or reduces its cross-section. An implant disposed distally of the opening can in this case be moved proximally only against an elastic force exerted by the elastic structural element. in each of the said variations the elastic structural element is preferably formed in such a way that the implant can be pushed proximally by a predetermined force exerted onto its distal end.

The elastic structural element is, for example, an O-ring made from rubber, silicone. perbunan or another elastic material, which is piaced around the cannula in the region of the opening.

The elastic structural element can also be formed as a tube, which is pushed over the cannula in the region of the opening in this cannula and is made from an elastic material. Elastic materials, which are suitable for a tube, are, for example, rubber, silicone, perbunan and the like. Alternatively, in a preferred embodiment, the tube can consist of a polymer material, which, after being fitted over the opening in the cannula, can be shrunk, for example, by heat, i.e. thermally. A thermally shrinkable tube of this type can consist, for example, of a modified polyolefin, such as, for example, the thermally shrinkable tubes, which can be obtained under the commercial name Altera MT2000 from the company Tyco Electronics Corporation, Swindon, U.K. which are also specified for medical applications and can be sterilised by irradiation with gamma rays.

An elastic tube pushed over the cannula in the region of the opening permits a large contact surface between the tube and the implant, by means of which the implant is fixedly held in the cannula in a particularly satisfactory manner. At the same time the large contact surface between the tube and cannula reliably prevents the elastic element from slipping on the cannula so that it is ensured that the implant is fixedly held even when handled incorrectly such as, for example, when removing a protective needle cap or the like. Furthermore. the use of a shrinkable tube also permits complete closure of the lateral cannula opening, which is advantageous in maintaining sterility.

When using a tube made from an elastic material, a tube is preferably selected which, in the unstretched state, has an inner diameter which is smaller than the outer periphery of the cannula.

When fitted on the cannula, the tube is preferably pushed completely over the lateral opening in the cannula, wherein it protrudes through the opening into the cannula bore and thus reduces the cross- section thereof in the region of the opening. An implant is preferably held firm in the region of the opening in the cannula. The force exerted by the tube is sufficient to prevent unintentional slipping of the implant, but is low enough that the implant can easily be pushed out during administration.

When using a tube made from a thermally shrinkable material, a tube is preferably selected which, in the initial condition, has an inner diameter which corresponds to the outer periphery of the cannula or is slightly larger. In order to fit the tube, it is pushed over the cannula so that it preferably completely covers the opening, and is then heated. The shrinkage of the tube causes it to lie tightly around the cannula and to penetrate through the opening into the cannula bore, whereby the cross-section is reduced in the region of the opening. An implant is preferably disposed in the region of the opening in the cannula bore prior to shrinkage of the tube, so that the tube also lies against the implant during shrinkage, and thus fixes the implant in the cannula. If a tube made from a sterilisable material is used, it is preferable to carry out sterilisation after fitting of the tube and possibly fixing of the implant.

In a particularly preferred manner the elastic structural element is transparent in order to permit a visual inspection of an implant, which is fixedly held in the cannula, through the opening.

The present invention also includes a cannula device with a cannula as described above and a cannula holder, which is connected to the cannula in a non-positive, positive or integrally bonded man ner.

Preferred exemplified embodiments of the present invention are described in more detail hereinunder with the aid of the attached figures in which: Figure 1 shows a schematic illustration of a longitudinal cross-sectional view through a cannula with a cannula holder; Figure 2 shows a schematic illustration of a longitudinal cross-sectional view through a cannula with a cannula holder; Figure 3 shows a schematic illustration of a longitudinal cross-sectional view through a cannula with a cannula holder; and Figure 4 shows a schematic illustration of a longitudinal cross-sectional view through a cannula with a cannula holder.

Figure 1 shows a schematic illustration of a longitudinal cross-sectional view through a cannula 10 and a cannula holder 30. The cannula 10 has a proximal end 12, for example, with a bevelled tip and optionally with ground facets. A distal end 14 of the cannula 10 is connected to the cannula holder 30 in a positive or integrally bonded manner. The cannula 10 is approximately in the form of a pipe with a circular or elliptical cross-section. A bore 16 extends from the proximal end 12 to the distal end 14 of the cannula 10. The cannula 10 consists, for example. of stainless steel or another pharmaceutically inert material. The cannula holder 30 is of, for example, a pharmaceutically inert synthetic material. An interruption in the illustration of the cannula 10 in Figure 1 indicates that the cannula can have a substantially greater overall length than shown in Figure 1.

The cannula 10 has a lateral opening 22 to the bore 16. The lateral opening 22 is, for example, drilled, milled or etched. Through the opening 22 an elastic structural element can exert a holding force on an implant in the bore 16. Examples of an elastic structural element are described in more detail hereinunder with reference to Figures 2 and 3.

Figures 2, 3 and 4 show schematic illustrations of longitudinal cross-sectional views through a respective cannula 10 and a cannula holder 30. Like Figure 1, the illustrations in Figures 2, 3 and 4 are not to scale. In particular, for example, the ratios between the length and the diameter of the cannula 10 and between the diameter and the wall thickness of the cannula 10 may deviate from the illustrations in Figures 2, 3 and 4. Similarly the angle of the tip at the proximal end 12, the location, the shape and the size of the opening 22 can deviate from the illustrations in the figures. Jagged edges on the cannula holder 30 indicate that only a part thereof is illustrated in each of Figures 2, 3 and 4. In the bore 16 of the cannula 10 an implant 40 is illustrated in each case. The shape and size of which can also deviate from the illustrations in Figures 2, 3 and 4.

Figure 2 shows an exemplified embodiment in which the above-mentioned elastic structural element is formed by an O-ring 24, which is placed around the cannula 10. In its non-stretched form the O- ring 24 has an inner periphery, which is smaller than the outer periphery of the cannula 10. When the O-ring 24 is placed around the cannula 10 it is stretched. When the O-ring 24 is placed around the cannula 10 at the opening 22 it engages at least partially into the opening 22. In this way it exerts a force on an implant 40 perpendicular to the axis of the cannula 10 when this implant is located in the region of the opening 22 and of the O-ring 24. The implant 40 is held by the resulting static friction between the O-ring 24 and the implant 40 and/or between the implant 40 and the inner wall of the cannula 10.

A predetermined minimum force is required to move the implant 40 in the bore 16 of the cannula 10.

The dimensions, the material and the nature of the surface of the O-ring 24, the shape and dimensions of the opening 22, the surface properties of the implant 40 and the inner wall of the cannula 10 are preferably selected in such a way that the static friction force amounts to a multiple of the weight of the implant 40.

The implant 40 can alternatively also have a peripheral groove or another recess into which the O- ring 24 engages. In this way the force exerted on the implant 40 by the O-ring 24 is further increased.

Figure 3 shows an alternative exemplified embodiment in which the elastic structural element is formed by an elastic lever 26 with an engagement end 28. The elastic lever and the engagement end are formed, for example. as one piece with the cannula holder 30. The engagement end 28 engages through the lateral opening 22 into the bore 16. The elastic lever 26 is deflected out of its inoperative position by an implant 40, which is located in the bore 16 in the region of the opening 22.

The engagement end 28 exerts an elastic force onto the implant 40, which force acts perpendicular to the axis of the cannula 10. In a similar manner as described above with the aid of Figure 2 this causes the implant 40 to be held in the bore 16 by static friction between the engagement end 28 and the implant 40 and/or between the implant 40 and the inner wall of the cannula 10.

In a similar manner as illustrated above with the aid of Figure 2, the implant 40 can alternatively also have a peripheral groove or another recess into which the engagement end 28 engages. In this way the force exerted by the elastic lever 26 and the engagement end 28 onto the implant 40 is further increased.

Figure 4 shows a further exemplified embodiment in which the above—mentioned elastic structural member is formed by a tube 25 which, in the region of the lateral opening 22, is pushed completely over the cannula 10. The tube 25 preferably consists of an elastic polymer material and, in its unstretched state, has an inner diameter, which is smaller than the outer periphery of the cannula 10 so that it engages at least partially into the opening 22. in this way it exerts a force perpendicular to the axis of the cannula 10 onto an implant 40 when this implant is located in the region of the opening 22 and of the tube 25 placed thereon. The implant 40 is held by means of the resulting static friction between the tube 25 and the implant 40 and/or between the implant 40 and the inner wall of the cannula 10. in order to facilitate the fitting of the tube 25 on the cannula 10 in the region of the opening 22, a tube 25 made from a thermally shrinkable polymer material can preferably be used which, in the initial condition, has an inner diameter which corresponds to the outer periphery of the cannula 10 or is slightly larger. After such a tube 25 has been positioned preferably completely over the lateral opening 22 in the cannula 10, the tube is shrunk by an appropriate supply of heat, whereby the tube 25 is fixed tightly on the outside of the cannula 10 and engages into the bore 16 in the region of the opening 22, The implant 40 is preferably disposed in the region of the opening 22 in the bore 16 of the cannuia 10 prior to shrinkage of the tube 25. The use of a transparent tube 25 advantageously allows a visual inspection of the position of the implant 40 below the opening 22.

Reference List Cannula Proximal end of the cannula 10 Distal end of the cannula 10 Bore of the cannula Lateral opening to the bore 16 O-ring Tube made of elastic material Elastic lever Engagement end Cannula holder Implant

Claims (1)

1. Claims 1Cannula (10) having: a proximal end (12) which is provided for insertion into tissue in which an implant is to be placed; a distal end (14) which is provided for connection to a cannula holder; a bore (16) for an implant. which extends from the distal end (14) to the proximal end (16); a lateral opening (22) to the bore (16), wherein the lateral opening (20) is disposed between the distal end (14) and the proximal end (16); and an elastic structural element (24; 25; 26, 28) which partially engages into the opening (22) to hold an implant (30) in the bore (16) by friction force. Cannula (10) as claimed in the preceding claim, wherein the elastic structural element comprises an O-ring (24) made from an elastic material, which is placed around the cannula (10) in the region of the opening (22). Cannula (10) as claimed in claim 1, wherein the elastic structural element comprises a tube (25) made from an elastic material, which is preferably pushed completely over the cannula (10) in the region of the opening (22). Cannula (10) as claimed in claim 3, wherein the elastic material of the tube (25) comprises a polymer, which is fitted on the cannula (10) by preferably thermal shrinkage. Cannula (10) as claimed in any one of the preceding claims, wherein the elastic structural element is transparent.