GB2241439A - Pellet implantor with lost motion means to prevent crushing - Google Patents

Abstract

An implantor 10 to inject a pellet containing a medication, into an animal via a hollow needle 15 comprises a push rod 42 which moves a pellet through the needle 15 so that the pellet can be delivered into a subcutaneous cavity formed by the needle 15. Associated with the push rod 42 is a spring 43 providing a lost motion mechanism so that the push rod 42 does not apply to the pellet an excessive force which would cause crushing of the pellet. The push rod 42 is moved by means of a trigger mechanism including a trigger 29 operated by the user to cause rotation of a reel 34. Wound about the reel is an elongated flexible strip 35 which is attached to the push rod 42. Operation of the trigger 29 causes the reel 34 to rotate, winding about it the metal strip 35. The implantor 10 is provided with a magazine 13 having a series of pellet containing cavities 21 which are successively aligned with the needle 15 and push rod 42. An indexing mechanism 47 associated with the push rod 42 causes indexing of the magazine 13 to align the next pellet to be injected with the needle 15. <IMAGE>

Description

b :-> 2 _el X _el A PELLET IMPLANTOR is The present invention relates to

Implantors to deliver pellets containing a medication, and more particularly but not exclusively to deliver such pellets into an animal.

Previously known Implantors which Inject a pellet containing a medication, Into an animal via a hollow needle, have suffered from the disadvantage that the pellet is prone to be crushed. This crushing results from the pellet being compressed.between the flesh of the animal and the push rod moving the pellet through the needle.

A further disadvantage of known pellet Implantors Is the complex mechanism required to move the push rod. This complex mechanism results from the distance the push rod Is required to travel In order to deliver the pellet to the extremity of the needle. It is the object of the present invention to overcome or substantially ameliorate the above disadvantages. There is disclosed herein an Implantor to deliver a pellet, said implantor comprising: a body; a hollow needle extending from said body and adapted to receive a pellet to be implanted; 20 a push rod mechanism Including a push rod movably mounted on said body to extend into said needle to move the pellet longitudinally within the needle from an Initial Inner position to an outer position expelled from the extremity of said needle; operator actuable means to cause movement of said rod assembly; and wherein said push rod mechanism Includes resilient means permitting lost motion between said operator actuable means and said push rod, said resilient means being stressed when said pellet is adjacent said extremity due to lost motion between said rod and said operator actuable means so that as the needle is withdrawn, the pellet Is expelled from the extremity of the needle to be located In a subcutaneous cavity formed by the needle.

There Is furtherdisclosed herein an Implantor to delivery a pellet, said implantor comprising:

a body; a hollow needle extending from said body and to receive a pellet to be implanted; a push rod movably mounted on said body to move the pellet longitudinally within the needle from an Inner position to an outer 1 - 2 position whereat the pellet is ejected from the extremity of said needle; operator actuable means to cause movement of said rod, said operator actuable means including a trigger means movably mounted on said body and manipulated by the user to be moved between a rest position and an actuated position, and movement transfer means operatively associated with the trigger means and including an elongated flexible element moved by said trigger means and connected to said rod to cause movement thereof.

A preferred form of the present invention will now be described by way of example with reference to the accompanying drawing, which schematically depicts In part sectioned side elevation a pellet implantor to implant pellets in an animal.

In the accompanying drawing there is schematically depicted a pellet Implantor 10. The implantor 10 has a hollow body 11 providing a handle 12 to be gripped by the user. The forward end of the body 11 is provided with a pellet magazine 13 which is provided with a plurality of sleeves 14, each sleeve 14 providing a cavity 21 which receives a pellet or plurality of pellets. The forward end of each cavity 21 is sealingly closed, preferably by a foil such as an aluminium foil. As the pellets are moved from their cavity 21, the foil Is ruptured. The magazine 13 is of a cylindrical configuration and is rotatably supported by a cylindrical flange 18. The magazine 13 is held in position by means of a threaded fastener 19 which engages the flange 18. The flange 18 is formed integral with a backing plate 20 fixed to the body 11. Enclosing the magazine 13 is a cover 22 whi ch i s pi votal ly mounted at i ts upper end 24 on the body 11.

The magazine 13 is also provided with raised portions 23 which are used to index the magazine 13.

The cover 22 is provided with an aperture 25 which receives a needle mounting 17 retained in position by a nut 26. Located on the mounting 17 Is the hollow needle 15 via a threaded cap 16. Extending through the mounting is a passage 27 aligned with the passage 28 extending through the needle 15.

Pivotally mounted on the handle 12 is a trigger 29 via a pin 30.

Extending between the handle 12 and the trigger 29 is a spring 31 which biases the trigger 29 to the position depicted. The upper end of the trigger 29 is formed with a rack gear 32 which engages a pinion 33. The pinion 33 is fixed to a reel 34 about which an elongated flexible element may be wound. Preferably. the element 35 is a metal strip which in the unwound configuration is upwardly convexed. One end of the element 35 is 1 i, - fixed to the reel 34, while the other end is attached to a carriage or slide 36. The body 11 Is provided with a pair of transversely aligned flanges 37, with each flange 37 being provided with a groove 38. The element 35 Is slidably received within the grooves 38 so as to be movable longitudinally thereof. The element 35 needs to resist buckling as it Is subjected to a compressive force when returning the slide 36 to the position depicted under the Influence of the spring 31.

The metal strip which constitutes the element 35, is curved In transverse cross-sectional so that the element resists buckling, yet bends about a transverse axis Vo permit winding on the reel 34.

The slide 36 has a downwardly extending projection 39 which is slidably received between the pair of aligned flanges 37 and Is fixed to one extremity of the element 35. Accordingly as the element 35 is wound onto the reel 34, the slide 36 moves In the direction of the arrow 40.

Mounted on the slide 36 is a push rod assembly 41, which includes a push rod 42 and a spring 43. One end of the push rod 41 passes through an aperture 44 In the slide 43 to permit lost motion between the slide 36 and the push rod 41. The extremity of the rod 42 adjacent the slide 36 Is provided with a nut 45 to limit movement In the direction of the arrow 40.

The push rod 41 is also provided with a radlally extending flange 59 which Is engaged by the spring 43. The spring 43 extends between the flange 59 and the slide 36. The other extremity of the push rod 42 Is received within a cylindrical flange 46 so as to be guided thereby and directed towards a cavity 21 of the magazine 13 aligned with the needle 15.

When the trigger 29 Is depressed, the reel 34 is rotated and the element 35 wound thereabout. The motion of the element 35 Is transferred to the slide 36 which moves the push rod 41 In the direction of the arrow 40. However upon sufficient resistance force being applied to the rod 42, the spring 43 will be compressed permitting lost motion between the trigger 29 and the push rod 41.

Movement of the push rod 41 through the cavity 21 moves the pellets contained in the cavity 21 Into the needle to a position adjacent the extremity of the needle 15. This movement of the pellets will also cause rupturing of the aluminium foil covering the exit opening of the cavity 21.

As the pellets reach the end of the needle 15 and engage the flesh of the animal, the progress of the pellets Is halted. This will then cause compression of the spring 43, which compression will prevent crushing of the pellets. As the implantor 10 Is drawn away from the animal and the needle 15 withdrawn, the spring 43 pushes the pellets out of the needle 15 so that the pellets are located in the subcutaneous needle cavity.

1 1 1 i 1 The magazine 13 is indexed by an indexing mechanism 47. The indexing mechanism 47 includes an indexing slide 48 which is provided with an indexing arm 49. The indexing arm 49 has a cam surface 50 which engages the projections 23 to cause indexing of the magazine 13. More particularly, the slide 48 is engaged and moved by projections 58 of the slide 36. The end face 51 of the slide 48 is abutted by the projections 58. Accordingly, the slide 48 is reciprocated between a retracted position (as illustrated) and an indexing position located further forward closer to the needle 15. The indexAng arm 49 is flexible and passes about the projections 23 via resilient defamation of the arm 49. During an injection stroke, the magazine 13 is prevented from indexing by location of the rod 41 in an aligned cavity 21. However on the return stroke, the rod 41 is free of the magazine 13, and the cam surface 50 engages one of the projections 23 to cause indexing of the magazine 13. To return the slide 49, there is provided a spring 52, which extends between the plate 20 and the slide 48.

To retain the slide 18 at its forward indexing position until the rod 41 Is withdrawn from the aligned cavity 21, there is provided a pivotally mounted catch 53 which is spring loaded via a spring 54 to engage the rear face 51 of the slide 48. When engaged with the face 51, the catch 53 prevents rearward movement of the slide 48. To move the catch 53 from a retaining position with respect to the slide 48, there is provided an elongated slide member 55 having an abutment portion 56 which engages the catch 53. The member 55 has an end portion 57 which is engaged by the slide 36 to cause rearward movement of the member 55 so that the abutmeft portion 56 engages the catch 53 and raises the catch to release the slide 48. Once the slide 48 is released, the arm 49 moves to cause Indexing of the magazine 13.

It should be appreciated that the trigger 29 is retained in its depressed position until the needle 15 is withdrawn. This then ensures that the pellets are delivered into the subcutaneous needle cavity.

1 1 1. An implantor to deliver a pellet, said Implantor comprising:

a body:

a hollow needle extending from said body and adapted to receive a pellet to be implanted:

a push rod mechanism Including a push rod movably mounted on said body to extend Into said needle to move the pellet longitudinally within the needle from an Initial Inner position to an outer position expelled from the extremity of said needle; operator actuable means to cause movement of said rod assembly; and wherein said push rod mechanism includes resilient means permitting lost motion between said operator actuable means and said push rod, said resilient means being stressed when said pellet Is adjacent said extremity due to lost motion between said rod and said operator actuable means so that as the needle Is withdrawn, the pellet is expelled from the extremity of the needle to be located in a subcutaneous cavity formed by the needle.

2. The implantor of claim 1, wherein said push rod mechanism includes a carriage slidably mounted on said body for movement along a linear path in the direction of said needle along said push rod, and said resilient means is a spring extending between said carriage and said push rod so that movement of said carriage towards said needle causes compression of said spring and movement of said push rod through the needle.

3. The implantor of claim 2. wherein said push rod passes through said carriage when said spring Is compressed, and said push rod has a flange which bears against said spring, while said spring Is positioned about said push rod.

4. The implantor of any one of claims 1, 2 or 3, wherein said operator actuable means Includes a trigger means movably mounted on said body and manipulated by the user to be moved between a rest position and an actuated position, and movement transfer means operatively associated with the trigger means and Including an elongated flexible element moved by said trigger means and connected to said rod to cause movement thereof.

5. An implantor to delivery a pellet, said Implantor comprising:

a body; a hollow needle extending from said body and to receive a pellet to be implanted; a push rod movably mounted on said body to move the pellet i longitudinally within the needle from an inner position to an outer position whereat the pellet is ejected from the extremity of said needle; operator actuable means to cause movement of said rod, said operator actuable means including a trigger means movably mounted on said body and manipulated by the user to be moved between a rest position and an actuated position, and movement transfer means operatively associated with the trigger means and Including an elongated flexible element moved by said trigger means and connected to said rod to cause movement thereof.

6. The implantor_pf claim 4 or 5, wherein said elongated flexible element is a metal strip.

7. The implantor of claim 6, wherein said metal strip is curved in transverse cross-section, and said trigger means includes a trigger moved by the user between said rest position and said actuated position, and a reel associated with said trigger and rotated thereby and about which said strip is wound when said trigger is in said rest position.

8. The implantor of any one of claims 1 to 7. further including a magazine movably supported on said body, said magazine having a plurality of pellet receiving cavities, which cavities are selectively aligned with said needle so that a pellet may be delivered from the aligned cavity to the interior of the needle by said push rod passing through said cavity, and means to cause indexing of said magazine to line successive cavities with the needle, and wherein said indexing means comprises an indexing member movably mounted on said body between a first and a second position, said indexing member being moved from said first position to said second position when said push rod is moved beyond a predetermined position atleast partly located In one of said cavities to prevent indexing of said magazine, and said indexing member engages said magazine to cause indexing thereof when It moves from said second position to said first position at which time said push rod is removed from being positioned within one of the cavities to thereby permit indexing of the magazine.

g. The implantor of claim 8, further including catch means to retain said indexing member in said second position until the push rod is withdrawn from the cavity aligned therewith.

10. The implantor of claim 9, further including a carriage associated with said push rod to cause movement thereof, and an actuator attached to said carriage and to engage said catch to cause disengagement of said catch with said indexing member when said push rod has been withdrawn from the cavity aligned therewith.

11. An implantor substantially as hereinbefore described with reference to the accompanying drawings.

S Published 1991 at The Patent Office. Concept House. Cardifr Road. Newporl. Gwent NP9 I RH. Further copies may be obtained from Sales Branch. Unit 6, Nine Mile Point. Cwrnfelinfach. Cross Keys. Newport. NPI 7HZ. Printed try Multiplex techniques lid. St Man, Cray. Rent --- II-J-1.,,, - rro oy Muluplex techniques lid. St Man, Cym%,.;(,t